JP4032744B2 - Positive electrode active material and non-aqueous electrolyte secondary battery using the same - Google Patents

Description

【００１１】
【化６】

【００１２】
以上のような正極活物質では、少なくともＮｉ及びＣｏを含有し、式１で示される層状構造の第１のリチウム遷移金属複合酸化物からなる第１の正極材料と、少なくともＮｉ及びＭｎを含有し、式２に示される層状構造の第２のリチウム遷移金属複合酸化物からなる第２の正極材料とが混合されており、第１の正極材料は高容量を有し、第２の正極材料は結晶構造が安定であることから、充放電容量の高容量化及びエネルギー密度の向上が図られ、高温環境下においても良好な充放電サイクル特性が得られる。
【００１３】
また、本発明に係る非水電解質二次電池は、正極集電体上に正極活物質を含有する正極合剤層が形成されてなる正極と、負極集電体上に負極活物質を含有する負極合剤層が形成されてなる負極と、非水電解質とを備える。正極活物質は、上記式１で示される層状構造の第１のリチウム遷移金属複合酸化物からなる第１の正極材料と、上記式２で示される層状構造の第２の遷移金属複合酸化物からなる第２の正極材料との混合物を有することを特徴とする。
【００１４】
この非水電解質二次電池では、少なくともＮｉ及びＣｏを含有し、式１で示される層状構造の第１のリチウム遷移金属複合酸化物からなる第１の正極材料と、少なくともＮｉ及びＭｎを含有し、式２に示される層状構造の第２のリチウム遷移金属複合酸化物からなる第２の正極材料とを混合した混合物を含有する正極活物質を用いることによって、第１の正極材料は高容量であり、第２の正極活物質は結晶構造が安定であることから、正極の充放電容量の高容量化及びエネルギー密度の向上が図られ、高温環境下においても良好な充放電サイクル特性が得られる。
【００１５】
【発明の実施の形態】
以下、本発明の実施の形態として示す正極活物質及びこの正極活物質を用いた非水電解質二次電池について、図面を参照して詳細に説明する。図１に示すように、非水電解質二次電池１は、帯状の正極２と、帯状の負極３とがセパレータ４を介して密着状態で巻回された電極体が、電池缶５の内部に充填されてなる。
【００１６】
正極２は、正極活物質と結合剤と導電剤とからなる正極合剤を正極集電体上に層状に塗布して形成される。結合剤には、ポリテトラフルオロエチレン、ポリフッ化ビニリデン、ポリエチレン等の熱可塑性樹脂を用いる。導電剤には、人工黒鉛やカーボンブラック等を用いる。なお、正極集電体としては、アルミニウム箔等の金属箔を用いる。
【００１７】
そして、正極活物質は、第１の正極材料と第２の正極材料とを混合した混合物を含有する。第１の正極材料は、層状構造を有し、化学式Ｌｉ _ｘ Ｎｉ _{１−ｙ−ｚ} Ｃｏ _ｙ Ｍ _Ｚ Ｏ _２ （但し、Mは、遷移金属、或いは長周期型元素周期表の２族、３族、４族の元素のうち１種の元素若しくは複数種であり、ｘ、ｙ、ｚの範囲は、０．９０≦ｘ＜１．１、０．０５≦y≦０．５０、０．０１≦z≦０．１０である。）で表される第１のリチウム遷移金属複合酸化物である。化学式Ｌｉ _ｘ Ｎｉ _{１−ｙ−ｚ} Ｃｏ _ｙ Ｍ _Ｚ Ｏ _２ 中のＭは、具体的に第１のリチウム遷移金属複合酸化物の結晶中で均一に分散できる元素を表しているが、特に好ましくはＦｅ、Ｃｏ、Ｚｎ、Ａｌ、Ｓｎ、Ｃｒ、Ｖ、Ｔｉ、Ｍｇ、Ｇａの中から１種或いは複数種からなる。
【００１８】
第２の正極材料は、層状構造を有し、化学式Ｌｉ _ｓ Ｎｉ _{１−ｔ−ｕ} Ｍｎ _ｔ Ｍ´ _ｕ Ｏ _２ （但し、M´は、遷移金属、或いは長周期型元素周期表の２族、３族、４族の元素のうち１種若しくは複数種であり、ｓ、ｔ、ｕは各々０．９０≦ｓ＜１．１、０．０５≦ｔ≦０．５０、０．０１≦ｕ≦０．３０である。）で表される第２のリチウム遷移金属複合酸化物である。化学式Ｌｉ _ｓ Ｎｉ _{１−ｔ−ｕ} Ｍｎ _ｔ Ｍ´ _ｕ Ｏ _２ 中のＭ´は、具体的に第２のリチウム遷移金属複合酸化物の結晶中を均一に分散できる元素を表しているが、特に好ましくは、Ｆｅ、Ｃｏ、Ｚｎ、Ａｌ、Ｓｎ、Ｃｒ、Ｖ、Ｔｉ、Ｍｇ、Ｇａの中から１種或いは複数種からなる。
【００１９】
第１のリチウム遷移金属複合酸化物及び第２のリチウム遷移金属複合酸化物の混合比は、正極活物質全体に対して１５重量％以上、８５重量％以下含有することが好ましく、更に好ましくは３０重量％以上、７０重量％以下を含有するようにする。正極活物質は、第１のリチウム遷移金属複合酸化物の混合比が１５重量％未満になると、第２のリチウム遷移金属複合酸化物の混合比が８５重量％を越え、正極活物質全体に対して低容量の第２のリチウム遷移複合酸化物の占める割合が多くなり、第１のリチウム遷移金属複合酸化物の高容量が活かされず正極活物質の初期容量が低下してしまう。また、第１のリチウム遷移金属複合酸化物の混合比が８５重量％を越えると、第２のリチウム遷移複合酸化物の混合比が１５重量％未満となり、正極活物質の結晶構造が不安定となるため、充放電を繰り返す度に結晶構造の劣化が進み高温環境下での充放電サイクル容量維持率が著しく低下してしまう。
【００２０】
この為、正極活物質は、第１のリチウム遷移金属複合酸化物及び第２のリチウム遷移金属複合酸化物の各々の混合比を１５重量％以上、８５重量％の範囲で混合することによって、充放電容量及び充放電に伴う結晶構造の変化を互いに第１のリチウム遷移金属複合酸化物と第２のリチウム遷移金属複合酸化物とが相殺し合うことにより、結晶構造の変化が小さくなるため充放電サイクル容量維持率の向上が図られる。
【００２１】
また、正極活物質は、第１のリチウム遷移金属複合酸化物及び第２のリチウム遷移金属複合酸化物の平均粒径を３０μm以下とすることが好ましく、更に好ましくは２μm以上、３０μm以下である。正極活物質は、第１のリチウム遷移金属複合酸化物及び第２のリチウム遷移金属複合酸化物の平均粒径を２μm未満にすると、正極活物質と電解質との接触面積が大きくなるため、電解液の分解が進行して高温環境下の特性が低下してしまう。逆に、正極活物質は、第１のリチウム遷移金属複合酸化物及び第２のリチウム遷移金属複合酸化物の平均粒径が３０μmを越えると、第１のリチウム遷移金属複合酸化物と第２のリチウム遷移金属複合酸化物との混合が不十分となり、高温環境下での初期容量の低下や充放電サイクル容量維持率の劣化が起こってしまう
【００２２】
この為、正極活物質は、第１のリチウム遷移金属複合酸化物及び第２のリチウム遷移金属複合酸化物の平均粒径を３０μm以下にすることによって、正極活物質と電解液との接触面積が小さくなり、また、第１のリチウム遷移金属複合酸化物と第２のリチウム遷移金属複合酸化物とが十分に混合され、高温環境下での初期容量の高容量化及び充放電サイクル容量維持率の向上が図られる。
【００２３】
更に、正極活物質は、第１のリチウム遷移金属複合酸化物中のＣｏの比率及び第２のリチウム遷移金属複合酸化物のＭｎの比率を０．０５以上、０．５０以下にすることが好ましい。正極活物質は、Ｃｏ及びＭｎの比率を０．０５未満にすることによって、第１のリチウム遷移金属複合酸化物及び第２のリチウム遷移金属複合酸化物の各結晶構造が不安定となり、充放電を繰り返す度に正極活物質の結晶構造が劣化して充放電サイクル特性が低下してしまう。逆に、正極活物質は、Ｃｏ及びＭｎの比率を０．５０以上にすることによって、充放電容量の低下を招く結晶構造を形成するため充放電容量が低下してしまう。
【００２４】
この為、正極活物質は、第１のリチウム遷移金属複合酸化物中のＣｏの比率及び第２のリチウム遷移金属複合酸化物のＭｎの比率を０．０５以上、０．５０以下にすることによって、結晶構造の劣化が抑制され充放電サイクル特性の向上が図られる。また、正極活物質は、Ｃｏ及びＭｎの比率を０．０５以上、０．５０以下にすることによって、高容量の結晶構造を形成することにより充放電容量の高容量化が図られる。
【００２５】
第１のリチウム遷移金属複合酸化物及び第２のリチウム遷移金属複合酸化物は、リチウム、ニッケル、コバルト、マンガン等の炭酸塩を各組成に応じて混合し、空気雰囲気又は酸素雰囲気中で６００〜１１００℃の温度範囲で焼成することにより得られる。なお、出発原料は、炭酸塩に限定されず、水酸化物、酸化物、硝酸塩、有機酸塩等からも同様に生成可能である。また、第１のリチウム遷移金属複合酸化物及び第２のリチウム遷移金属複合酸化物は、リチウム、ニッケル、コバルト、マンガン等を含有する複合水酸化物や複合炭酸塩等を原料として用いることも可能である。
【００２６】
以上のような正極活物質は、高容量な第１のリチウム遷移金属複合酸化物と安定な結晶構造を形成している第２のリチウム遷移金属複合酸化物とを混合した混合物からなることにより、充放電容量の高容量化及び結晶構造の安定化が図られる。従って、正極活物質は、充放電容量の高容量化、高エネルギー密度化、及び高温環境下においての充放電サイクル容量維持率の向上が図られる。また、正極活物質は、第１のリチウム遷移金属複合酸化物と第２のリチウム遷移金属複合酸化物との混合比、平均粒径、及び第１のリチウム遷移金属複合酸化物中のＣｏ及び第２のリチウム遷移金属複合酸化物中のＭｎの比率、或いは第１のリチウム遷移金属複合酸化物及び第２のリチウム遷移金属複合酸化物中の添加元素の有無を上述したように規定することによって、より優れた初期容量及び充放電サイクル容量維持率が得られる。
【００２７】
負極３は、負極活物質と結合剤とを含有する負極合剤を負極集電体上に塗布して形成される。負極活物質には、対リチウム金属２．０Ｖ以下の電位で電気化学的にリチウムをドープ・脱ドープできる材料を用いる。例えば、難黒鉛化性炭素、人造黒鉛、天然黒鉛、熱分解炭素類、コークス類（ピッチコークス、ニードルコークス、石油コークス等）、グラファイト類、ガラス状炭素類、有機高分子化合物焼成体（フェノール樹脂、フラン樹脂等を適当な温度で焼成し炭素化したもの）、炭素繊維、活性炭、カーボンブラック類等の炭素質材料を使用することができる。
【００２８】
また、負極活物質としては、リチウムと合金を形成可能な金属及びリチウムと合金を形成可能な金属からなる合金化合物も利用可能である。リチウムと合金形成可能な金属としては、半導体元素も含めることとして、例えば、Ｍｇ、Ｂ、Ａｌ、Ｇａ、Ｉｎ、Ｓｉ、Ｓｎ、Ｐｂ、Ｓｂ、Ｂｉ、Ｃｄ、Ａｇ、Ｚｎ、Ｈｆ、Ｚｒ、Ｙである。更には、酸化ルテニウム、酸化モリブデン、酸化タングステン、酸化チタン、酸化スズ等の比較的電位が低電位で、リチウムイオンをドープ・脱ドープする酸化物やその他の窒化物なども同様に使用可能である。なお、負極集電体としては、銅箔等の金属を用いる。また、導電剤としては、正極２を作製する際に用いた導電剤と同様の人工黒鉛やカーボンブラック等を用いる。
【００２９】
上述した正極２及び負極３の作製方法は、正極活物質及び負極活物質に結合剤、導電剤等を添加し溶剤を加えて塗布する方法、正極活物質及び負極活物質に結合剤等を添加し加熱して塗布する方法、正極活物質及び負極活物質を単独或いは導電剤、更には結合剤と混合して成型等の処理を施して成型体電極を作成する方法等がとられているが、それらに限定されるものではない。
【００３０】
例えば、正極２の作製方法は、第１のリチウム遷移金属複合酸化物と第２のリチウム遷移金属複合酸化物とを混合して得られた正極活物質に、上述した導電剤と結合剤とを所定の割合で混合して正極合剤を作製し、この正極合剤をＮ−メチル−２−ビロリドン等の有機溶媒に分散させてスラリー状にする。次に、スラリー状とした正極合剤を正極集電体上に均一に塗布して正極合剤層を形成し、乾燥後、成型して正極２が得られる。
【００３１】
また、負極３の作製方法としては、上述した負極活物質と結合剤とを所定の割合で混合した負極合剤をスラリー状とする。次に、スラリー状とした負極合剤を負極集電体上に均一に塗布して負極合剤層を形成し、乾燥後、成型して負極３が得られる。なお、上述した正極２及び負極３の作製方法において、結合剤の有無にかかわらず、正極活物質及び負極活物質に熱を加えたまま加圧成型することにより強度を有した正極２及び負極３を作製することもできる。
【００３２】
上述した正極２及び負極３を用いた非水電解質二次電池１の作製方法には、正極２と負極３との間にセパレータ４を介して巻芯の周囲を捲回する作製方法、又は正極２と負極３との間にセパレータ４を挟み正極２及び負極３を積層する積層方法等がある。
【００３３】
電解質には、非水溶媒に電解質塩を溶解させた非水電解液、電解質塩を含有させた固体電解質、或いは非水溶媒と電解質塩とからなる非水電解液をマトリックス高分子に含浸させてゲル状としたゲル状電解質のいずれも用いることができる。
【００３４】
非水電解液は、有機溶媒と電解質塩とを適宜組み合わせて調製される。有機溶媒は、非水電解液系の電池に使用されているものであればいずれも用いることができる。有機溶媒には、例えば、プロピレンカーボネート、エチレンカーボネート、ビニレンカーボネート、ジエチルカーボネート、ジメチルカーボネート、１，２−ジメトキシエタン、１，２−ジエトキシエタン、γ−ブチロラクトン、テトラビドロフラン、２−メチルテトラヒドロフラン、１，３−ジオキソラン、４メチル１，３ジオキソラン、ジエチルエーテル、スルホラン、メチルスルホラン、アセトニトリル、プロピオニトリル、アニソール、酢酸エステル、酪酸エステル、プロピオン酸エステル等がある。電解質塩には、非水電解液系の電池に用いられるものであればいずれも用いることができ、例えば、ＬｉＣｌＯ、ＬｉＡｓＦ，ＬｉＰＦ、ＬｉＢＦ、ＬｉＢ（ＣＨ）、ＣＨＳＯＬｉ、ＣＦＳＯＬｉ、ＬｉＣｌ、ＬｉＢｒ等がある。
【００３５】
固体電解質には、リチウムイオン導電性を有する材料であれば無機固体電解質、高分子固体電解質のいずれも用いられる。無機固体電解質には、例えば窒化リチウム、よう化リチウム等がある。高分子固体電解質は、上述した電解質塩を含有する高分子化合物からなる。高分子化合物には、ポリエチレンオキサイド、図架橋体などのエーテル系高分子、ポリメタクリレートエステル系及びアクリレート系などを単独或いは分子中に共重合、又は混合して用いることができる。
【００３６】
ゲル状電解質のマトリックス高分子には、上記非水電解液を吸収してゲル化するものであれば種々の有機高分子を使用できる。マトリックス高分子には、例えば、ポリビニリデンフルオロライドやポリビニリデンフルオロライド−ｃｏ−ヘキサフルオロプロピレン等のフッ素系高分子、ポリエチレンオキサイドや図架橋体等のエーテル系高分子、又はポリアクリロニトリル等がある。特に、ゲル状電解質のマトリックス高分子には、酸化還元安定性からフッ素系高分子を用いることが望ましい。また、ゲル状電解質のマトリックスは、非水電解液中の電解質塩を含有させることによりイオン導電性が付与されている。
【００３７】
円筒型の非水電解質二次電池１の作製方法は、先ず、上述したように作製された正極２と負極３とを多孔性ポリオレフィンフィルムからなるセパレータ４を介して多数回巻回して、渦巻き型の電極体を作製する。渦巻き型の電極体の上下両面に絶縁板６を配置して、ニッケルめっき処理を施した鉄製の電池缶５に収納する。正極２の集電をとるために、アルミニウム製正極リード７の一端を正極集電体から導出して、他端を電流遮断用薄板８に溶接して電池蓋９と電気的に接続する。また、負極３の集電をとるために、ニッケル負極リード１０の一端を負極集電体から導出して、他端を電池缶５の底部に溶接する。
【００３８】
次に、上述した電極体が組み込まれた電池缶５内に、調製した非水電解液を注入後、絶縁封ロガスケット１１を介して電池缶５をかしめることにより電池蓋９が固定さる。なお、非水電解質二次電池１において、正極リード７及び負極リード１０に接続するセンターピン１２が設けられているとともに、非水電解質二次電池１内部の圧力が所定の値よりも高くなった場合に、非水電解質電池１内部の気体を抜くための安全弁１３、及び非水電解質二次電池１内部の温度上昇を防止するためのＰＴＣ（positive temperture coefficient）素子１４が設けられている。
【００３９】
以上のように構成された非水電解質二次電池は、正極２を形成する正極活物質に高容量な第１のリチウム遷移金属複合酸化物と安定な結晶構造を形成している第２のリチウム遷移金属複合酸化物とを混合した混合物からなることにより、充放電容量の高容量化及び結晶構造の安定性が図られる。従って、この非水電解質二次電池１は、充放電容量の高容量化及び高エネルギー密度の向上と共に、常温及び高温環境下のおいての充放電サイクル容量維持率の向上が図られる。
【００４０】
また、非水電解質二次電池１の形状は、特に限定されないため、円筒型、角型、コイン型、ボタン型、ラミネートシール型等の種々の形状にすることができるが、角形電池の場合に捲回する方式で本発明を適用すると有効である。その場合には、巻芯の内径を電池製造の捲回時に使用される楕円形状の芯の中でも、最も曲率の大きい部分の直径に合わせて作製する。
【００４１】
【実施例】
以下、本発明を適用した正極活物質を用いた非水電解質二次電池の実施例及び比較例について具体的に説明する。ここでは、非水電解質二次電池の形状を円筒型の非水電解質二次電池とした。
【００４２】
実施例１
先ず、第１のリチウム遷移金属複合酸化物を次のようにして作製した。第１のリチウム遷移金属複合酸化物の原料には、市販の水酸化リチウム、一酸化ニッケル、酸化コバルトを用いた。第１のリチウム遷移金属複合酸化物は、水酸化リチウム、一酸化ニッケル、酸化コバルトを次のような配合で混合した。なお、実施例１では、遷移金属、或いは長周期型元素周期表の２族、３族、４族の元素のうち１種の元素若しくは複数種からなる添加物Ｍを第１のリチウム遷移金属複合酸化物に添加せずに作製した。従って、第１のリチウム遷移金属複合酸化物の化学式Ｌｉ _ｘ Ｎｉ _{１−ｙ−ｚ} Ｃｏ _ｙ Ｍ _Ｚ Ｏ _２ のＬｉ、Ｎｉ、Ｃｏ、Ｍ元素の比ｘ、１−ｙ−ｚ、ｙ、ｚが、ｘ＝１．０２、１−ｙ−ｚ＝０．７０、ｙ＝０．３０、ｚ＝０となるように配合した。
【００４３】
次に、第１のリチウム遷移金属複合酸化物は、水酸化リチウム、一酸化ニッケル、酸化コバルトを上述した配合で混合したものを８００℃の酸素気流中で１０時間焼成した後、粉砕して得られる。そして、得られた粉末を原子吸光分析機器により分析した結果、第１のリチウム遷移金属複合酸化物は化学式Ｌｉ _１．０２ Ｎｉ _０．７０ Ｃｏ _０．３ Ｏ _２ で表されることが確認された。また、この粉末の平均粒径をレーザ一図析法により測定した結果、１５μmと確認された。また、この粉末のＸ線回析測定を行った結果、得られた回析パターンは、International Centre for Diffraction Date（以下ＩＣＤＤ）の０９−００６３にあるＬｉＮｉＯ _２ の回析パターンに類似しており、ＬｉＮｉＯ _２ と同様の層状構造を形成していていることが確認された。
【００４４】
次に、第２のリチウム遷移金属複合酸化物を次のようにして作製した。第２のリチウム遷移金属複合酸化物の原料には、市販の水酸化リチウム、一酸化ニッケル、二酸化マンガンを用いた。第２のリチウム遷移金属複合酸化物は、水酸化リチウム、一酸化ニッケル、二酸化マンガンを次のような配合で混合した。なお、第１のリチウム遷移金属複合酸化物と同様に第２のリチウム遷移金属複合酸化物に、遷移金属、或いは長周期型元素周期表の２族、３族、４族の元素のうち１種の元素若しくは複数種からなる添加物Ｍ´を第２のリチウム遷移金属複合酸化物に添加せずに作製した。第２のリチウム遷移金属複合酸化物の化学式Ｌｉ _ｓ Ｎｉ _{１−ｔ−ｕ} Ｍｎ _ｔ Ｍ´ _ｕ Ｏ _２ のＬｉ、Ｎｉ、Ｍｎ、Ｍ´元素の比ｓ、１−ｔ−ｕ、ｔ、ｕが、ｓ＝１．０２、１−ｔ−ｕ＝０．６５、ｔ＝０．３５、ｕ＝０となるように混合した。
【００４５】
次に、第２のリチウム遷移金属複合酸化物は、水酸化リチウム、一酸化ニッケル、二酸化マンガンを上述した比になるように混合したものを８００℃の酸素気流中で１０時間焼成した後、粉砕して得られた。そして、得られた粉末を原子吸光分析機器により分析した結果、第２のリチウム遷移金属複合酸化物の化学式Ｌｉ _１．０２ Ｎｉ _０．６５ Ｍｎ _０．３５ Ｏ _２ で表されることが確認された。また、この粉末の平均粒径をレーザ一図析法により測定した結果、１５μmが確認された。また、この粉末のＸ線回析測定を行った結果、得られた回析パターンは、ＩＣＤＤの０９−００６３にあるＬｉＮｉＯ _２ の回析パターンに類似しており、ＬｉＮｉＯ _２ と同様の層状構造を形成していていることが確認された。
【００４６】
次に、正極を作製した。先ず、上述した第１のリチウム遷移金属複合酸化物と第２のリチウム遷移金属複合酸化物とを混合して正極活物質を作製した。正極活物質は、第１のリチウム遷移金属複合酸化物と第２のリチウム遷移金属複合酸化物との混合比が第１のリチウム遷移金属複合酸化物対第２のリチウム遷移金属複合酸化物＝５０重量％対５０重量％となるように混合して作製した。次に、第１のリチウム遷移金属複合酸化物と第２のリチウム遷移金属複合酸化物を混合して得られた正極活物質８６重量％、導電剤としてグラファイト１０重量％、結合剤としてポリフッ化ビニリデン（以下、ＰＶｄＦと称する）４重量％を混合し、有機溶媒Ｎ−メチル−２−ビロリドン（以下、ＮＭＰと称する）に分散させて得られた正極合剤をスラリー状とした。次に、スラリー状にした正極合剤を厚さ２０μmの帯状のアルミニウム箔の両面に均一に塗布して正極合剤層を形成し、乾燥後、ローラープレス機で圧縮して帯状の正極を得た。
【００４７】
次に、負極を作製した。負極は、負極活物質に粉末状の人造黒鉛を用い、人工黒鉛９０重量％にＰＶｄＦ１０重量％を混合し、ＮＭＰに分散させて得られた負極合剤をスラリー状とした。このスラリー状にした負極合剤を厚さ１０μmの銅箔の両面に均一に塗布して負極合剤層を形成し、乾燥後にローラープレス機で圧縮して負極を得た。
【００４８】
次に、非水電解液を作製した。非水電解液は、エチレンカーボネートとメチルエチルカーボネートとの体積混合比を１対１とする混合溶液を、濃度１mol/dm ^３ となるように溶媒ＬｉＰＦに溶解させて得られた。
【００４９】
次に、円筒型の非水電解質二次電池を作製した。先ず、以上のように作製された正極と負極とを多孔性ポリオレフィンフィルムからなるセパレータを介して多数回巻回して、渦巻き型の電極体を作製した。渦巻き型の電極体の上下両面に絶縁板を配置して、ニッケルめっき処理を施した鉄製の電池缶に収納した。正極の集電をとるために、アルミニウム製正極リードの一端を正極集電体から導出して、他端を電流遮断用薄板に溶接することで電流遮断用薄板を介して電池蓋と電気的に接続した。また、負極の集電をとるために、ニッケル負極リードの一端を負極集電体から導出して、他端を電池缶の底部に溶接した。
【００５０】
次に、上述した電極体が組み込まれた電池缶内に、調製した非水電解液を注入後、絶縁封ロガスケットを介して電池缶をかしめることにより電池蓋が固定されて、外径１８mm、高さ６５mmの円筒型の非水電解質二次電池が作製された。なお、非水電解質二次電池において、正極リード及び負極リードに接続するセンターピンが設けられているとともに、非水電解質二次電池内部の圧力が所定の値よりも高くなった場合に、非水電解質電池内部の気体を抜くための安全弁、及び非水電解質二次電池内部の温度上昇を防止するためのＰＴＣ（positive temperturecoefficient）素子が設けた。
【００５１】
実施例２
実施例２では、第１のリチウム遷移金属複合酸化物の原料として、水酸化リチウム、一酸化ニッケル、酸化コバルトの他に、水酸化アルミニウムを用いて、これらの原料を次のような割合で混合した。第１のリチウム遷移金属複合酸化物の化学式Ｌｉ _ｘ Ｎｉ _{１−ｙ−ｚ} Ｃｏ _ｙ Ａｌ _ｚ Ｏ _２ のＬｉ、Ｎｉ、Ｃｏ、Ａｌ元素の比ｘ、１−ｙ−ｚ、ｙ、ｚが、ｘ＝１．０２、１−ｙ−ｚ＝０．７０、ｙ＝０．２５、ｚ＝０．０５となるように混合した以外は実施例１と同様にして、Ｌｉ _１．０２ Ｎｉ _０．７０ Ｃｏ _０．２５ Ａｌ _０．０５ Ｏ _２ の第１のリチウム遷移金属複合酸化物を作製した。そして、この第１のリチウム遷移金属複合酸化物を用いたこと以外は実施例１と同様にして非水電解質二次電池を作製した。
【００５２】
実施例３
実施例３では、第２のリチウム遷移金属複合酸化物の原料として、水酸化リチウム、一酸化ニッケル、酸化コバルトの他に、水酸化アルミニウムを用いて、これらの原料を次のような割合で混合した。第２のリチウム遷移金属複合酸化物の化学式Ｌｉ _ｓ Ｎｉ _{１−ｔ−ｕ} Ｍｎ _ｔ Ａｌ _ｕ Ｏ _２ のＬｉ、Ｎｉ、Ｍｎ、Ａｌ元素の比ｓ、１−ｔ−ｕ、ｔ、ｕがｓ＝１．０２、１−ｔ−ｕ＝０．６５、ｔ＝０．３０、ｕ＝０．０５となるように配合し混合した以外は実施例１と同様にして、Ｌｉ _１．０２ Ｎｉ _０．６５ Ｍｎ _０．３０ Ａｌ _０．０５ Ｏ _２ の第２のリチウム遷移金属複合酸化物を作製した。その第２のリチウム遷移金属複合酸化物を用いたこと以外は、実施例１と同様にして非水電解質二次電池を作製した
【００５３】
実施例４
実施例４では、第１のリチウム遷移金属複合酸化物を実施例２の第１のリチウム遷移金属複合酸化物と同様にして、化学式Ｌｉ _１．０２ Ｎｉ _０．７０ Ｃｏ _０．２５ Ａｌ _０．０５ Ｏ _２ の第１のリチウム遷移金属複合酸化物を作製した。第２のリチウム遷移金属複合酸化物は、実施例３の第２のリチウム遷移金属複合酸化物と同様にして、化学式Ｌｉ _１．０２ Ｎｉ _０．６５ Ｍｎ _０．３ Ａｌ _０．０５ Ｏ _２ の第２のリチウム遷移金属複合酸化物を作製した。これら第１のリチウム遷移金属複合酸化物と第２のリチウム遷移金属複合酸化物とを用いた以外は、実施例１と同様にして非水電解質二次電池を作製した。
【００５４】
実施例５
実施例５は、第１のリチウム遷移金属複合酸化物の原料として、水酸化リチウム、一酸化ニッケル、酸化コバルトの他に、水酸化アルミニウムに換えて水酸化鉄を用いて、第１のリチウム遷移金属複合酸化物の化学式Ｌｉ _ｘ Ｎｉ _{１−ｙ−ｚ} Ｃｏ _ｙ Ｆｅ _Ｚ Ｏ _２ のＬｉ、Ｎｉ、Ｃｏ、Ｆｅ元素の比ｘ、１−ｙ−ｚ、ｙ、ｚが、ｘ＝１．０２、１−ｙ−ｚ＝０．７０、ｙ＝０．２５、ｚ＝０．０５となるように混合した以外は実施例４と同様にして、Ｌｉ _１．０２ Ｎｉ _０．７０ Ｃｏ _０．２５ Ｆｅ _０．０５ Ｏ _２ の第１のリチウム遷移金属複合酸化物を作製した。この第１のリチウム遷移金属複合酸化物を用いた以外は実施例４と同様にして非水電解質二次電池を作製した
【００５５】
実施例６
実施例６は、第１のリチウム遷移金属複合酸化物の原料として、水酸化リチウム、一酸化ニッケル、酸化コバルトの他に、水酸化アルミニウムに換えて酸化スズを用いて、第１のリチウム遷移金属複合酸化物の化学式Ｌｉ _ｘ Ｎｉ _{１−ｙ−ｚ} Ｃｏ _ｙ Ｓｎ _Ｚ Ｏ _２ のＬｉ、Ｎｉ、Ｃｏ、Ｓｎ元素の比ｘ、１−ｙ−ｚ、ｙ、ｚが、ｘ＝１．０２、１−ｙ−ｚ＝０．７０、ｙ＝０．２５、ｚ＝０．０５となるように混合した以外は実施例４と同様にして、Ｌｉ _１．０２ Ｎｉ _０．７０ Ｃｏ _０．２５ Ｓｎ _０．０５ Ｏ _２ の第１のリチウム遷移金属複合酸化物を作製した。この第１のリチウム遷移金属複合酸化物を用いたこと以外は実施例４と同様にして非水電解質二次電池を作製した。
【００５６】
実施例７
実施例７は、第１のリチウム遷移金属複合酸化物の原料として、水酸化リチウム、一酸化ニッケル、酸化コバルトの他に、水酸化アルミニウムに換えて酸化クロムを用いて、第１のリチウム遷移金属複合酸化物の化学式Ｌｉ _ｘ Ｎｉ _{１−ｙ−ｚ} Ｃｏ _ｙ Ｃｒ _Ｚ Ｏ _２ のＬｉ、Ｎｉ、Ｃｒ、Ａｌ元素の比ｘ、１−ｙ−ｚ、ｙ、ｚが、ｘ＝１．０２、１−ｙ−ｚ＝０．７０、ｙ＝０．２５、ｚ＝０．０５となるように混合した以外は実施例４と同様にして、Ｌｉ _１．０２ Ｎｉ _０．７０ Ｃｏ _０．２５ Ｃｒ _０．０５ Ｏ _２ の第１のリチウム遷移金属複合酸化物を作製した。この第１のリチウム遷移金属複合酸化物を用いたこと以外は実施例４と同様にして非水電解質二次電池を作製した。
【００５７】
実施例８
実施例８は、第１のリチウム遷移金属複合酸化物の原料として、水酸化リチウム、一酸化ニッケル、酸化コバルトの他に、水酸化アルミニウムに換えて五酸化バナジウムを用いて、第１のリチウム遷移金属複合酸化物の化学式Ｌｉ _ｘ Ｎｉ _{１−ｙ−ｚ} Ｃｏ _ｙ Ｖ _Ｚ Ｏ _２ のＬｉ、Ｎｉ、Ｃｏ、Ｖ元素の比ｘ、１−ｙ−ｚ、ｙ、ｚが、ｘ＝１．０２、１−ｙ−ｚ＝０．７０、ｙ＝０．２５、ｚ＝０．０５となるように混合した以外は実施例４と同様にして、Ｌｉ _１．０２ Ｎｉ _０．７０ Ｃｏ _０．２５ Ｖ _０．０５ Ｏ _２ の第１のリチウム遷移金属複合酸化物を作製した。この第１のリチウム遷移金属複合酸化物を用いたこと以外は実施例４と同様にして非水電解質二次電池を作製した。
【００５８】
実施例９
実施例９は、第１のリチウム遷移金属複合酸化物の原料として、水酸化リチウム、一酸化ニッケル、酸化コバルトの他に、水酸化アルミニウムに換えて酸化チタンを用いて、第１のリチウム遷移金属複合酸化物の化学式Ｌｉ _ｘ Ｎｉ _{１−ｙ−ｚ} Ｃｏ _ｙ Ｔｉ _Ｚ Ｏ _２ のＬｉ、Ｎｉ、Ｃｏ、Ｔｉ元素の比ｘ、１−ｙ−ｚ、ｙ、ｚが、ｘ＝１．０２、１−ｙ−ｚ＝０．７０、ｙ＝０．２５、ｚ＝０．０５となるように混合した以外は実施例４と同様にして、Ｌｉ _１．０２ Ｎｉ _０．７０ Ｃｏ _０．２５ Ｔｉ _０．０５ Ｏ _２ の第１のリチウム遷移金属複合酸化物を作製した。この第１のリチウム遷移金属複合酸化物を用いたこと以外は実施例４と同様にして非水電解質二次電池を作製した。
【００５９】
実施例１０
実施例１０は、第１のリチウム遷移金属複合酸化物の原料として、水酸化リチウム、一酸化ニッケル、酸化コバルトの他に、水酸化アルミニウムに換えて酸化マグネシウムを用いて、第１のリチウム遷移金属複合酸化物の化学式Ｌｉ _ｘ Ｎｉ _{１−ｙ−ｚ} Ｃｏ _ｙ Ｍｇ _Ｚ Ｏ _２ のＬｉ、Ｎｉ、Ｃｏ、Ｍｇ元素の比ｘ、１−ｙ−ｚ、ｙ、ｚが、ｘ＝１．０２、１−ｙ−ｚ＝０．７０、ｙ＝０．２５、ｚ＝０．０５となるように混合した以外は実施例４と同様にして、Ｌｉ _１．０２ Ｎｉ _０．７０ Ｃｏ _０．２５ Ｍｇ _０．０５ Ｏ _２ の第１のリチウム遷移金属複合酸化物を作製した。この第１のリチウム遷移金属複合酸化物を用いたこと以外は実施例４と同様にして非水電解質二次電池を作製した。
【００６０】
実施例１１
実施例１１は、第１のリチウム遷移金属複合酸化物の原料として、水酸化リチウム、一酸化ニッケル、酸化コバルトの他に、水酸化アルミニウムに換えて硝酸ガリウムを用いて、第１のリチウム遷移金属複合酸化物の化学式Ｌｉ _ｘ Ｎｉ _{１−ｙ−ｚ} Ｃｏ _ｙ Ｇａ _Ｚ Ｏ _２ のＬｉ、Ｎｉ、Ｃｏ、Ｇａ元素の比ｘ、１−ｙ−ｚ、ｙ、ｚが、ｘ＝１．０２、１−ｙ−ｚ＝０．７０、ｙ＝０．２５、ｚ＝０．０５となるように混合した以外は実施例４と同様にして、Ｌｉ _１．０２ Ｎｉ _０．７０ Ｃｏ _０．２５ Ｇａ _０．０５ Ｏ _２ の第１のリチウム遷移金属複合酸化物を作製した。この第１のリチウム遷移金属複合酸化物を用いたこと以外は実施例４と同様にして非水電解質二次電池を作製した。
【００６１】
実施例１２
実施例１２は、第２のリチウム遷移金属複合酸化物の原料として、水酸化リチウム、一酸化ニッケル、酸化コバルトの他に、水酸化アルミニウムに換えて水酸化鉄を用いて、第２のリチウム遷移金属複合酸化物の化学式Ｌｉ _ｓ Ｎｉ _{１−ｔ−ｕ} Ｍｎ _ｔ Ｆｅ _ｕ Ｏ _２ のＬｉ、Ｎｉ、Ｍｎ、Ｆｅ元素の比ｓ、１−ｔ−ｕ、ｔ、ｕがｓ＝１．０２、１−ｔ−ｕ＝０．６５、ｔ＝０．３０、ｕ＝０．０５となるように配合し混合した以外は実施例４と同様にして、Ｌｉ _１．０２ Ｎｉ _０．６５ Ｍｎ _０．３０ Ｆｅ _０．０５ Ｏ _２ の第２のリチウム遷移金属複合酸化物を作製した。この第１のリチウム遷移金属複合酸化物を用いたこと以外は実施例４と同様にして非水電解質二次電池を作製した。
【００６２】
実施例１３
実施例１３は、第２のリチウム遷移金属複合酸化物の原料として、水酸化リチウム、一酸化ニッケル、酸化コバルトの他に、水酸化アルミニウムに換えて酸化コバルトを用いて、第２のリチウム遷移金属複合酸化物の化学式Ｌｉ _ｓ Ｎｉ _{１−ｔ−ｕ} Ｍｎ _ｔ Ｃｏ _ｕ Ｏ _２ のＬｉ、Ｎｉ、Ｍｎ、Ｃｏ元素の比ｓ、１−ｔ−ｕ、ｔ、ｕがｓ＝１．０２、１−ｔ−ｕ＝０．６５、ｔ＝０．３０、ｕ＝０．０５となるように配合し混合した以外は実施例４と同様にして、Ｌｉ _１．０２ Ｎｉ _０．６５ Ｍｎ _０．３０ Ｃｏ _０．０５ Ｏ _２ の第２のリチウム遷移金属複合酸化物を作製した。この第２のリチウム遷移金属複合酸化物を用いたこと以外は実施例４と同様にして非水電解質二次電池を作製した。
【００６３】
実施例１４
実施例１４は、第２のリチウム遷移金属複合酸化物の原料として、水酸化リチウム、一酸化ニッケル、酸化コバルトの他に、水酸化アルミニウムに換えて水酸化亜鉛を用いて、第２のリチウム遷移金属複合酸化物の化学式Ｌｉ _ｓ Ｎｉ _{１−ｔ−ｕ} Ｍｎ _ｔ Ｚｎ _ｕ Ｏ _２ のＬｉ、Ｎｉ、Ｍｎ、Ｚｎ元素の比ｓ、１−ｔ−ｕ、ｔ、ｕがｓ＝１．０２、１−ｔ−ｕ＝０．６５、ｔ＝０．３０、ｕ＝０．０５となるように配合し混合した以外は実施例４と同様にして、Ｌｉ _１．０２ Ｎｉ _０．６５ Ｍｎ _０．３０ Ｚｎ _０．０５ Ｏ _２ の第２のリチウム遷移金属複合酸化物を作製した。この第２のリチウム遷移金属複合酸化物を用いたこと以外は実施例４と同様にして非水電解質二次電池を作製した。
【００６４】
実施例１５
実施例１５は、第２のリチウム遷移金属複合酸化物の原料として、水酸化リチウム、一酸化ニッケル、酸化コバルトの他に、水酸化アルミニウムに換えて酸化スズを用いて、第２のリチウム遷移金属複合酸化物の化学式Ｌｉ _ｓ Ｎｉ _{１−ｔ−ｕ} Ｍｎ _ｔ Ｓｎ _ｕ Ｏ _２ のＬｉ、Ｎｉ、Ｍｎ、Ｓｎ元素の比ｓ、１−ｔ−ｕ、ｔ、ｕがｓ＝１．０２、１−ｔ−ｕ＝０．６５、ｔ＝０．３０、ｕ＝０．０５となるように配合し混合した以外は実施例４と同様にして、Ｌｉ _１．０２ Ｎｉ _０．６５ Ｍｎ _０．３０ Ｓｎ _０．０５ Ｏ _２ の第２のリチウム遷移金属複合酸化物を作製した。この第２のリチウム遷移金属複合酸化物を用いたこと以外は実施例４と同様にして非水電解質二次電池を作製した。
【００６５】
実施例１６
実施例１６は、第２のリチウム遷移金属複合酸化物の原料として、水酸化リチウム、一酸化ニッケル、酸化コバルトの他に、水酸化アルミニウムに換えて酸化クロムを用いて、第２のリチウム遷移金属複合酸化物の化学式Ｌｉ _ｓ Ｎｉ _{１−ｔ−ｕ} Ｍｎ _ｔ Ｃｒ _ｕ Ｏ _２ のＬｉ、Ｎｉ、Ｍｎ、Ｃｒ元素の比ｓ、１−ｔ−ｕ、ｔ、ｕがｓ＝１．０２、１−ｔ−ｕ＝０．６５、ｔ＝０．３０、ｕ＝０．０５となるように配合し混合した以外は実施例１と同様にして、Ｌｉ _１．０２ Ｎｉ _０．６５ Ｍｎ _０．３０ Ｃｒ _０．０５ Ｏ _２ の第２のリチウム遷移金属複合酸化物を作製した。この第２のリチウム遷移金属複合酸化物を用いたこと以外は実施例４と同様にして非水電解質二次電池を作製した。
【００６６】
実施例１７
実施例１７は、第２のリチウム遷移金属複合酸化物の原料として、水酸化リチウム、一酸化ニッケル、酸化コバルトの他に、水酸化アルミニウムに換えて五酸化バナジウムを用いて、第２のリチウム遷移金属複合酸化物の化学式Ｌｉ _ｓ Ｎｉ _{１−ｔ−ｕ} Ｍｎ _ｔ Ｖ _ｕ Ｏ _２ のＬｉ、Ｎｉ、Ｍｎ、Ｖ元素の比ｓ、１−ｔ−ｕ、ｔ、ｕがｓ＝１．０２、１−ｔ−ｕ＝０．６５、ｔ＝０．３０、ｕ＝０．０５となるように配合し混合した以外は実施例４と同様にして、Ｌｉ _１．０２ Ｎｉ _０．６５ Ｍｎ _０．３０ Ｖ _０．０５ Ｏ _２ の第２のリチウム遷移金属複合酸化物を作製した。この第２のリチウム遷移金属複合酸化物を用いたこと以外は実施例４と同様にして非水電解質二次電池を作製した。
【００６７】
実施例１８
実施例１８は、第２のリチウム遷移金属複合酸化物の原料として、水酸化リチウム、一酸化ニッケル、酸化コバルトの他に、水酸化アルミニウムに換えて酸化チタンを用いて、第２のリチウム遷移金属複合酸化物の化学式Ｌｉ _ｓ Ｎｉ _{１−ｔ−ｕ} Ｍｎ _ｔ Ｔｉ _ｕ Ｏ _２ のＬｉ、Ｎｉ、Ｍｎ、Ｔｉ元素の比ｓ、１−ｔ−ｕ、ｔ、ｕがｓ＝１．０２、１−ｔ−ｕ＝０．６５、ｔ＝０．３０、ｕ＝０．０５となるように配合し混合した以外は実施例４と同様にして、Ｌｉ _１．０２ Ｎｉ _０．６５ Ｍｎ _０．３０ Ｔｉ _０．０５ Ｏ _２ の第２のリチウム遷移金属複合酸化物を作製した。この第２のリチウム遷移金属複合酸化物を用いたこと以外は実施例４と同様にして非水電解質二次電池を作製した。
【００６８】
実施例１９
実施例１９は、第２のリチウム遷移金属複合酸化物の原料として、水酸化リチウム、一酸化ニッケル、酸化コバルトの他に、水酸化アルミニウムに換えて酸化マグネシウムを用いて、第２のリチウム遷移金属複合酸化物の化学式Ｌｉ _ｓ Ｎｉ _{１−ｔ−ｕ} Ｍｎ _ｔ Ｍｇ _ｕ Ｏ _２ のＬｉ、Ｎｉ、Ｍｎ、Ｍｇ元素の比ｓ、１−ｔ−ｕ、ｔ、ｕがｓ＝１．０２、１−ｔ−ｕ＝０．６５、ｔ＝０．３０、ｕ＝０．０５となるように配合し混合した以外は実施例４と同様にして、Ｌｉ _１．０２ Ｎｉ _０．６５ Ｍｎ _０．３０ Ｍｇ _０．０５ Ｏ _２ の第２のリチウム遷移金属複合酸化物を作製した。この第２のリチウム遷移金属複合酸化物を用いたこと以外は実施例４と同様にして非水電解質二次電池を作製した。
【００６９】
実施例２０
実施例２０は、第２のリチウム遷移金属複合酸化物の原料として、水酸化リチウム、一酸化ニッケル、酸化コバルトの他に、水酸化アルミニウムに換えて硝酸ガリウムを用いて、第２のリチウム遷移金属複合酸化物の化学式Ｌｉ _ｓ Ｎｉ _{１−ｔ−ｕ} Ｍｎ _ｔ Ｇａ _ｕ Ｏ _２ のＬｉ、Ｎｉ、Ｍｎ、Ｇａ元素の比ｓ、１−ｔ−ｕ、ｔ、ｕがｓ＝１．０２、１−ｔ−ｕ＝０．６５、ｔ＝０．３０、ｕ＝０．０５となるように配合し混合した以外は実施例４と同様にして、Ｌｉ _１．０２ Ｎｉ _０．６５ Ｍｎ _０．３０ Ｇａ _０．０５ Ｏ _２ の第２のリチウム遷移金属複合酸化物を作製した。この第２のリチウム遷移金属複合酸化物を用いたこと以外は実施例４と同様にして非水電解質二次電池を作製した。
【００７０】
実施例２１
実施例２１は、第１のリチウム遷移金属複合酸化物及び第２のリチウム遷移金属複合酸化物の混合比を第１のリチウム遷移金属複合酸化物：第２のリチウム遷移金属複合酸化物＝１５重量％：８５重量％として混合した以外は実施例４と同様にして正極活物質を作製した。この正極活物質を用いた以外は、実施例４と同様にして非水電解質二次電池を作製した。
【００７１】
実施例２２
実施例２２は、第１のリチウム遷移金属複合酸化物及び第２のリチウム遷移金属複合酸化物の混合比を第１のリチウム遷移金属複合酸化物：第２のリチウム遷移金属複合酸化物＝３０重量％：７０重量％となるように混合した以外は実施例４と同様にして正極活物質を作製した。この正極活物質を用いた以外は、実施例４と同様にして非水電解質二次電池を作製した。
【００７２】
実施例２３
実施例２３は、第１のリチウム遷移金属複合酸化物及び第２のリチウム遷移金属複合酸化物の混合比を第１のリチウム遷移金属複合酸化物：第２のリチウム遷移金属複合酸化物＝７０重量％：３０重量％となるように混合した以外は実施例４と同様にして正極活物質を作製した。この正極活物質として用いた以外は実施例４と同様にして非水電解質二次電池を作製した。
【００７３】
実施例２４
実施例２４は、第１のリチウム遷移金属複合酸化物及び第２のリチウム遷移金属複合酸化物の混合比を第１のリチウム遷移金属複合酸化物：第２のリチウム遷移金属複合酸化物＝８５重量％：１５重量％となるように混合した以外は実施例４と同様にして正極活物質を作製した。この正極活物質を用いた以外は実施例４と同様にして非水電解質二次電池を作製した。
【００７４】
実施例２５
実施例２５は、第１のリチウム遷移金属複合酸化物は、作製条件を変えて平均平均粒径２μmの第１のリチウム遷移金属複合酸化物を実施例４と同様にして作製した。この第１のリチウム遷移金属複合酸化物を用いた以外は実施例４と同様にして非水電解質二次電池を作製した。
【００７５】
実施例２６
実施例２６は、第１のリチウム遷移金属複合酸化物は、作製条件を変えて平均平均粒径８μmの第１のリチウム遷移金属複合酸化物を実施例４と同様にして作製した。この第１のリチウム遷移金属複合酸化物を用いる以外は実施例４と同様にして非水電解質二次電池を作製した。
【００７６】
実施例２７
実施例２７は、第１のリチウム遷移金属複合酸化物は、作製条件を変えて平均平均粒径２０μmの第１のリチウム遷移金属複合酸化物を作製した以外は実施例４と同様にして作製した。これ以外は実施例４と同様にして非水電解質二次電池を作製した。
【００７７】
実施例２８
実施例２８は、第１のリチウム遷移金属複合酸化物の作製条件を変えて、平均平均粒径３０μmの第１のリチウム遷移金属複合酸化物を実施例４と同様にして作製した。この第１のリチウム遷移金属複合酸化物を用いる以外実施例４と同様にして非水電解質二次電池を作製した。
【００７８】
実施例２９
実施例２９は、実施例４において第２のリチウム遷移金属複合酸化物の作製条件を換えて、平均粒径２μmの第２のリチウム遷移金属複合酸化物を実施例４の第２のリチウム遷移金属複合酸化物と同様して作製した。この第２のリチウム遷移金属複合酸化物を用いる以外は実施例４と同様にして非水電解質二次電池を作製した。
【００７９】
実施例３０
実施例３０は、第２のリチウム遷移金属複合酸化物の作製条件を換えて、平均平均粒径９μmの第２のリチウム遷移金属複合酸化物を実施例４の第２のリチウム遷移金属複合酸化物と同様にして作製した。この第２のリチウム遷移金属複合酸化物を用いる以外は実施例４と同様にして非水電解質二次電池を作製した。
【００８０】
実施例３１
実施例３１は、第２のリチウム遷移金属複合酸化物の作製条件を換えて、平均平均粒径１８μmの第２のリチウム遷移金属複合酸化物を実施例４の第２のリチウム遷移金属複合酸化物と同様にして作製した。この第２のリチウム遷移金属複合酸化物を用いる以外は実施例４と同様にして非水電解質二次電池を作製した。
【００８１】
実施例３２
実施例３２は、第２のリチウム遷移金属複合酸化物の作製条件を換えて、平均粒径３０μmの第２のリチウム遷移金属複合酸化物を実施例４の第２のリチウム遷移金属複合酸化物と同様にして作製した。この第２のリチウム遷移金属複合酸化物を用いる以外は実施例４と同様にして非水電解質二次電池を作製した。
【００８２】
実施例３３
実施例３３は、第１のリチウム遷移金属複合酸化物中のコバルトの組成の比ｙを０．０５に換えて第１のリチウム遷移金属複合酸化物中のＬｉ、Ｎｉ、Ｃｏ、Ａｌ元素の組成の比ｘ、１−ｙ−ｚ、ｙ、ｚが、ｘ＝１．０２、１−ｙ−ｚ＝０．９０、ｙ＝０．０５、ｚ＝０．０５となるように混合して、第１のリチウム遷移金属複合酸化物を作製した。これ以外は実施例４と同様にして非水電解質二次電池を作製した。
【００８３】
実施例３４
実施例３４は、第１のリチウム遷移金属複合酸化物中のコバルトの組成の比ｙを０．５０に変えて、Ｌｉ、Ｎｉ、Ｃｏ、Ａｌ元素の組成の比ｘ、１−ｙ−ｚ、ｙ、ｚが、ｘ＝１．０２、１−ｙ−ｚ＝０．４５、ｙ＝０．５０、ｚ＝０．０５となるように混合して、第１のリチウム遷移金属複合酸化物を実施例４の第１のリチウム遷移金属複合酸化物と同様にして作製した。この第１のリチウム遷移金属複合酸化物を用いる以外は実施例４と同様にして非水電解質二次電池を作製した。
【００８４】
実施例３５
実施例３５は、第２のリチウム遷移金属複合酸化物中のマンガンの組成の比ｔを０．０５に変えて、Ｌｉ、Ｎｉ、Ｍｎ、Ａｌ元素の組成の比ｓ、１−ｔ−ｕ、ｔ、ｕが、ｓ＝１．０２、１−ｔ−ｕ＝０．９０、ｔ＝０．０５、ｕ＝０．０５となるように混合して、第２のリチウム遷移金属複合酸化物を実施例４の第２のリチウム遷移金属複合酸化物と同様にして作製した。この第２のリチウム遷移金属複合酸化物を用いること以外は実施例４と同様にして非水電解質二次電池を作製した。
【００８５】
実施例３６
実施例３６は、第２のリチウム遷移金属複合酸化物中のマンガンの組成の比ｔを０．５０に変えて第２のリチウム遷移金属複合酸化物中のＬｉ、Ｎｉ、Ｍｎ、Ａｌ元素の組成の比がｓ、１−ｔ−ｕ、ｔ、ｕが、ｓ＝１．０２、１−ｔ−ｕ＝０．４５、ｔ＝０．５０、ｕ＝０．０５となるように混合して、第２のリチウム遷移金属複合酸化物を実施例４と同様にして作製した。この第２のリチウム遷移金属複合酸化物を用いる以外は実施例４と同様にして非水電解質二次電池を作製した。
【００８６】
比較例１
比較例１は、第１のリチウム遷移金属複合酸化物の原料として水酸化リチウム、一酸化ニッケル、酸化コバルトを次のような配合で混合した。第１のリチウム遷移金属複合酸化物の化学式Ｌｉ _ｘ Ｎｉ _{１−ｙ−ｚ} Ｃｏ _ｙ Ｍ _Ｚ Ｏ _２ のＬｉ、Ｎｉ、Ｃｏ、Ｍ元素の比ｘ、１−ｙ−ｚ、ｙ、ｚが、ｘ＝１．０２、１−ｙ−ｚ＝０．７０、ｙ＝０．３０、ｚ＝０となるように配合した。第１のリチウム遷移金属複合酸化物は、化学式Ｌｉ _１．０２ Ｎｉ _０．７０ Ｃｏ _０．３０ Ｏ _２ で表され、実施例４の第１のリチウム遷移金属複合酸化物と同様に作製した。比較例１では、第２のリチウム遷移金属複合酸化物を用いずに第１のリチウム遷移金属複合酸化物を単独で正極活物質を作製した。この正極活物質を用いること以外は実施例４と同様にして非水電解質二次電池を作製した。
【００８７】
比較例２
比較例２は、第２のリチウム遷移金属複合酸化物の原料として、市販の水酸化リチウム、一酸化ニッケル、二酸化マンガンを用いた。第２のリチウム遷移金属複合酸化物は、化学式Ｌｉ _１．０２ Ｎｉ _０．７ Ｍｎ _０．３ Ｏ _２ で表される第１のリチウム遷移金属複合酸化物を実施例４と同様にして作製した。比較例２では、第１のリチウム遷移複合酸化物を用いずに第２のリチウム遷移金属複合酸化物を単独で正極活物質を作製した。この正極活物質を用いる以外は実施例４と同様にして非水電解質二次電池を作製した。
【００８８】
比較例３
比較例３は、第１のリチウム遷移金属複合酸化物及び第２のリチウム遷移金属複合酸化物の混合比を、第１のリチウム遷移金属複合酸化物：第２のリチウム遷移金属複合酸化物＝１０重量％：９０重量％として混合した以外は実施例４と同様にして正極活物質を作製した。この正極活物質を用いる以外は実施例４と同様にして非水電解質二次電池を作製した。
【００８９】
比較例４
比較例４は、第１のリチウム遷移金属複合酸化物及び第２のリチウム遷移金属複合酸化物の混合比を、第１のリチウム遷移金属複合酸化物：第２のリチウム遷移金属複合酸化物＝９０重量％：１０重量％として混合した以外は実施例４と同様にして正極活物質を作製した。こ以外は実施例４と同様にして非水電解質二次電池を作製した。
【００９０】
比較例５
比較例５は、第１のリチウム遷移金属複合酸化物の作製条件を変えて、平均粒径１μmの第１のリチウム遷移金属複合酸化物を実施例４と同様にして作製した。この第１のリチウム遷移金属複合酸化物を用いた以外は実施例４と同様にして非水電解質二次電池を作製した。
【００９１】
比較例６
比較例６は、第１のリチウム遷移金属複合酸化物の作製条件を変えて、平均粒径４０μmの第１のリチウム遷移金属複合酸化物を実施例４と同様にして作製した。この第１のリチウム遷移金属複合酸化物を用いた以外は実施例４と同様にして非水電解質二次電池を作製した。
【００９２】
比較例７
比較例７は、第２のリチウム遷移金属複合酸化物の作製条件を変えて、平均粒径１μmの第２のリチウム遷移金属複合酸化物を実施例４と同様にして作製した。この第２のリチウム遷移金属複合酸化物を用いた以外は実施例４と同様にして非水電解質二次電池を作製した。
【００９３】
比較例８
比較例８は、第２のリチウム遷移金属複合酸化物の作製条件を変えて、平均粒径４０μmの第２のリチウム遷移金属複合酸化物を実施例４と同様にして作製した。この第２のリチウム遷移金属複合酸化物を用いた以外は実施例４と同様にして非水電解質二次電池を作製した。
【００９４】
比較例９
比較例９は、第１のリチウム遷移金属複合酸化物中のコバルトの組成の比ｙを０．０１に変えて、Ｌｉ、Ｎｉ、Ｃｏ、Ａｌ元素の組成の比ｘ、１−ｙ−ｚ、ｙ、ｚが、ｘ＝１．０２、１−ｙ−ｚ＝０．９４、ｙ＝０．０１、ｚ＝０．０５となるように混合して、第１のリチウム遷移金属複合酸化物を実施例４の第１のリチウム遷移金属複合酸化物と同様にして作製した。この第１のリチウム遷移金属複合酸化物を用いる以外は実施例４と同様にして非水電解質二次電池を作製した。
【００９５】
比較例１０
比較例１０は、第１のリチウム遷移金属複合酸化物中のコバルトの組成の比ｙを０．６０に変えて、Ｌｉ、Ｎｉ、Ｃｏ、Ａｌ元素の組成の比ｘ、１−ｙ−ｚ、ｙ、ｚが、ｘ＝１．０２、１−ｙ−ｚ＝０．３５、ｙ＝０．６０、ｚ＝０．０５となるように混合して、第１のリチウム遷移金属複合酸化物を実施例４の第１のリチウム遷移金属複合酸化物と同様にして作製した。この第１のリチウム遷移金属複合酸化物を用いる以外は実施例４と同様にして非水電解質二次電池を作製した。
【００９６】
比較例１１
比較例１１は、第２のリチウム遷移金属複合酸化物中のマンガンの組成の比ｔを０．０１に変えて、Ｌｉ、Ｎｉ、Ｍｎ、Ａｌ元素の組成の比ｓ、１−ｔ−ｕ、ｔ、ｕが、ｓ＝１．０２、１−ｔ−ｕ＝０．９４、ｔ＝０．０１、ｕ＝０．０５となるように混合して、第２のリチウム遷移金属複合酸化物を実施例４の第２のリチウム遷移金属複合酸化物と同様にして作製した。この第２のリチウム遷移金属複合酸化物を用いること以外は実施例４と同様にして非水電解質二次電池を作製した。
【００９７】
比較例１２
比較例１２は、第２のリチウム遷移金属複合酸化物中のマンガンの組成の比ｔを０．６０に変えて、Ｌｉ、Ｎｉ、Ｍｎ、Ａｌ元素の組成の比ｓ、１−ｔ−ｕ、ｔ、ｕが、ｓ＝１．０２、１−ｔ−ｕ＝０．３５、ｔ＝０．６０、ｕ＝０．０５となるように混合して、第２のリチウム遷移金属複合酸化物を実施例４の第２のリチウム遷移金属複合酸化物と同様にして作製した。この第２のリチウム遷移金属複合酸化物を用いること以外は実施例４と同様にして非水電解質二次電池を作製した。
【００９８】
次に、以上のように作製した実施例及び比較例の非水電解質二次電池について、環境温度２３℃、充電電圧４．２０Ｖ、充電電流１０００mA、充電時間２．５時間の条件で充電を行った後、充電電流１５００mA、終止電圧２．７５Vで放電を行い初期容量を測定した。更に、同条件で充放電を繰り返し、２３℃における１００サイクル目の放電容量を測定して、初期容量に対する１００サイクル目の容量維持率を求めた。また、環境温度を５０℃に設定して、他の条件を環境温度２３℃の場合と同様にして、５０℃での充放電を繰り返した時の１００サイクル目の容量維持率の測定を行った。
【００９９】
以下に、実施例１乃至実施例２０、比較例１及び比較例２における初期容量、２３℃における１００サイクル容量維持率及び５０℃における１００サイクル容量維持率の評価結果を表１に示す。
【０１００】
【表１】

【０１０１】
表１に示す評価結果から、第１のリチウム遷移金属複合酸化物と第２のリチウム遷移金属複合酸化物を混合した混合物を正極活物質に用いた実施例１乃至実施例２０では、第１のリチウム遷移金属複合酸化物を単独で正極活物質を形成している比較例１と比べて、２３℃及び５０℃における１００サイクル容量維持率の向上が図られていることが分かる。
【０１０２】
比較例１は、第１のリチウム遷移金属複合酸化物を単独で正極活物質に用いた場合であり、遷移金属、或いは元素周期表の２族、３族、４族の元素のうち１種若しくは複数種からなるものが添加されていないため、結晶構造が不安定であるため充放電を繰り返す度に結晶構造が劣化している。その為、第１のリチウム遷移金属複合酸化物を単独で正極活物質に用いた場合は、充放電サイクル容量維持率が低下してしまう。特に、高温環境下における充放電サイクル容量維持率は、高温により結晶構造の劣化が促進され、更に電解質の分解によって著しく低下している。
【０１０３】
一方、実施例１乃至実施例２０は、第１のリチウム遷移金属複合酸化物の他に第２のリチウム遷移金属複合酸化物を混合することによって、第２のリチウム遷移金属複合酸化物の結晶構造が安定であることから、充放電に伴う正極活物質の結晶構造の変化が小さくなり、充放電に伴う正極活物質全体の結晶構造の劣化が抑制される。その為、正極活物質は、２３℃及び５０℃における１００サイクル容量維持率が向上が図られている。
【０１０４】
また、表１に示す評価結果から、実施例１乃至実施例２０では、第２のリチウム遷移金属複合酸化物を単独で正極活物質を形成している比較例２と比べて、初期容量の高容量化が図られていることが分かる。
【０１０５】
比較例２では、第２のリチウム遷移金属複合酸化物を単独で正極活物質に用いた場合であり、遷移金属、或いは元素周期表の２族、３族、４族の元素のうち１種若しくは複数種からなるものが添加されていないため、第２のリチウム遷移金属複合酸化物が低容量であるため初期容量が低下している。
【０１０６】
一方、実施例１乃至実施例２０は、第２のリチウム遷移金属複合酸化物の他に第１のリチウム遷移金属複合酸化物を混合することによって、第１のリチウム遷移金属複合酸化物が高容量であることから、正極活物質全体の初期容量が向上している。
【０１０７】
以上のことから、非水電解質二次電池を作製する際に、正極活物質に第１のリチウム遷移金属複合酸化物と第２のリチウム遷移金属複合酸化物とを混合した混合物を用いることによって、初期容量の高容量化、高エネルギー密度化及び充放電サイクル容量維持率の向上に有効であることが明らかである。なお、実施例１のように、第１のリチウム遷移金属複合酸化物及び第２のリチウム遷移金属複合酸化物に、遷移金属、或いは元素周期表の２族、３族、４族中から選ばれる元素を加えなくても、初期容量の高容量化及び充放電サイクル容量維持率の向上が図られる。
【０１０８】
次に、実施例４、実施例２１乃至実施例２４、比較例３及び比較例４における初期容量、２３℃における１００サイクル容量維持率及び５０℃における１００サイクル容量維持率の評価結果を表２に示す。なお、第１のリチウム遷移金属複合酸化物及び第２のリチウム遷移金属複合酸化物に添加する添加物Ｍ及び添加物Ｍ´は、実施例４、実施例２１乃至実施例２４、比較例３及び比較例４すべてＡｌである。
【０１０９】
【表２】

【０１１０】
表２に示す評価結果から、第１のリチウム遷移金属複合酸化物及び第２のリチウム遷移金属複合酸化物の混合比を正極活物質全体に対して１５重量％以上、８５重量％以下にした実施例１、実施例２１乃至実施例２４では、第１のリチウム遷移金属複合酸化物を１０％、第２のリチウム遷移金属複合酸化物を９０％とした比較例３と比べて、初期容量の高容量化が図られていることが分かる。
【０１１１】
比較例３は、正極活物質全体に対して第１のリチウム遷移金属複合酸化物１０重量％と第２のリチウム遷移金属複合酸化物９０重量％とを混合した混合物を正極活物質に用いることによって、低容量の第２のリチウム遷移金属複合酸化物が正極活物質の多くを占めているため、実施例４及び実施例２１乃至実施２４に比べて初期容量が著しく低下している。
【０１１２】
一方、実施例４、及び実施例２１乃至実施例２４は、正極活物質全体に対して第２のリチウム遷移金属複合酸化物の混合比を１５重量％以上、８５重量％以下の範囲で混合することによって、高容量の第１のリチウム遷移金属複合酸化物が正極活物質全体に対して適切な重量％で含有されているため初期容量の高容量化が図られている。また、実施例１、及び実施例２１乃至実施例２４では、第１のリチウム遷移金属複合酸化物の混合比が増加するに従って初期容量の高容量化が図られている。
【０１１３】
また、表２に示す評価結果から、実施例４、及び実施例２１乃至実施例２４は、第１のリチウム遷移金属複合酸化物９０％、第２のリチウム遷移金属複合酸化物１０％とした比較例４に比べて、２３℃及び５０℃における１００サイクル容量維持率の向上が図られていることが分かる。
【０１１４】
比較例４は、正極活物質全体に対して第１のリチウム遷移金属複合酸化物９０％と第２のリチウム遷移金属複合酸化物１０％とを混合した混合物を正極活物質に用いることによって、結晶構造の不安定な第１のリチウム遷移金属複合酸化物が正極活物質の多くを占めているため、充放電を繰り返す度に結晶構造の劣化が促進されて充放電サイクル容量維持率が低下している。また、特に、正極活物質は、高温環境下において結晶構造の劣化が促進され、更に電解質の劣化も伴い５０℃における１００サイクル容量維持率が著しく低下している。
【０１１５】
一方、実施例４、及び実施例２１乃至実施例２４は、正極活物質全体に対して第１のリチウム遷移金属複合酸化物の混合比を１５重量％以上、８５重量％以下の範囲で混合し、正極活物質全体に対して適当な重量％で混合されることによって、充放電に伴う正極活物質の結晶構造の変化が抑制され、充放電サイクル容量維持率が向上している。
【０１１６】
以上のことから、正極活物質は、非水電解質二次電池を作製する際に、全体に対して第１のリチウム遷移金属複合酸化物の混合比を１５重量％以上、８５重量％以下の範囲で混合することによって、初期容量の高容量化及び充放電サイクル容量維持率の向上が図られることが分かる。
【０１１７】
次に、実施例４、実施例２７乃至実施例３２、及び比較例５乃至比較例８における初期容量、２３℃における１００サイクル容量維持率及び５０℃における１００サイクル容量維持率の評価結果を表３に示す。なお、第１のリチウム遷移金属複合酸化物と第２のリチウム遷移金属複合酸化物との混合比は、第１のリチウム遷移金属複合酸化物：第２のリチウム遷移金属複合酸化物＝５０重量％：５０重量％である。
【０１１８】
【表３】

【０１１９】
表３の評価結果から、第１のリチウム遷移金属複合酸化物及び第２のリチウム遷移金属複合酸化物の各々の平均粒径を２μm以上、３０μm以下の範囲とした実施例４、実施例２７乃至実施例３２と、第１のリチウム遷移金属複合酸化物或いは第２のリチウム遷移金属複合酸化物のどちらか一方を１μm若しくは４０μmとし、他方を１５μmとした比較例５乃至比較例８とを比べると、５０℃１００サイクル容量維持率の向上が図られていることが分かる。
【０１２０】
比較例５乃至比較例８では、第１のリチウム遷移金属複合酸化物或いは第２のリチウム遷移金属複合酸化物のどちらか一方の平均粒径が２μm未満、他方が１５μmとすると、正極活物質と電解液との接触面積が大きくなりすぎるため、電解質の分解が進行して、実施例４、実施例２７乃至実施例３２と比較すると５０℃におけるサイクル容量維持率が低下している。また、平均粒径が３０μmを越えると、第１のリチウム遷移金属複合酸化物と第２のリチウム遷移金属複合酸化物の混合が不十分となり、サイクル容量維持率が低下して、特に５０℃におけるサイクル容量維持率が低下している。
【０１２１】
一方、実施例４、実施例２５乃至実施例２８では、第１のリチウム遷移金属複合酸化物の平均粒径を２μm以上、３０μm以下の範囲として、第２のリチウム遷移金属複合酸化物の平均粒径を１５μmと一定にして混合した混合物を正極活物質に用いることで、正極活物質と電解液との接触面積が小さくなり、また第１のリチウム遷移金属複合酸化物と第２のリチウム遷移金属複合酸化物とが十分に混合される。従って、実施例４、実施例２５乃至実施例２８では、比較例５乃至比較例８と比較すると５０℃における１００サイクル容量維持率の向上が図られる。
【０１２２】
以上のことから、正極活物質は、非水電解質二次電池を作製する際に、第１のリチウム遷移金属複合酸化物及び第２のリチウム遷移金属複合酸化物の平均粒径を２μm以上、３０μm以下の範囲にすることより、５０℃における１００サイクル容量維持率が向上する。
【０１２３】
次に、実施例４、実施例３３乃至実施例３６、及び比較例９乃至比較例１２における初期容量、２３℃における１００サイクル容量維持率及び５０℃における１００サイクル容量維持率の評価結果を表４に示す。なお、第１のリチウム遷移金属複合酸化物と第２のリチウム遷移金属複合酸化物との混合比は、第１のリチウム遷移金属複合酸化物対第２のリチウム遷移金属複合酸化物＝５０重量％対５０重量％である。
【０１２４】
【表４】

【０１２５】
表４の評価結果から、第１のリチウム遷移金属複合酸化物（Ｌｉ _ｘ Ｎｉ _{１−ｙ−ｚ} Ｃｏ _ｙ Ｍ _Ｚ Ｏ _２ ）中のＣｏの比率ｙ及び第２のリチウム遷移金属複合酸化物（Ｌｉ _ｓ Ｎｉ _{１−ｔ−ｕ} Ｍｎ _ｔ Ｍ´ _ｕ Ｏ _２ ）中のＭｎの比率ｔの範囲を０．０５以上、０．５０以下とした実施例１及び実施例３３乃至実施例３６は、比率ｙ或いはｔの範囲を０．０５以下とし、一方を０．０５以上、０．５０以下の範囲とした比較例９乃至比較例１１とを比べて、５０℃１００サイクル容量維持率の向上が図られていることが分かる。
【０１２６】
比較例９では、１のリチウム遷移金属複合酸化物のＣｏの比率ｙを０．０１として、比較例１２は、第２のリチウム遷移金属複合酸化物のＭｎの比率ｔを０．０１とした場合である。このように比較例９乃至比較例１１では、第１のリチウム遷移金属複合酸化物中のＣｏの比率ｙを０．０１、若しくは第２のリチウム遷移金属複合酸化物中のＭｎの比率ｔを０．０１にすることによって、各々の結晶構造が不安定となり充放電を繰り返す度に正極活物質の結晶構造が劣化して充放電サイクル容量維持率が低下している。また、特に、正極活物質は、高温環境下において結晶構造の劣化が促進されて５０℃における１００サイクル容量維持率が著しく低下している。
【０１２７】
一方、実施例４及び実施例３３乃至実施例３６では、第１のリチウム遷移金属複合酸化物中のＣｏの比率ｙ及び第２のリチウム遷移金属複合酸化物（Ｌｉ _ｓ Ｎｉ _{１−ｔ−ｕ} Ｍｎ _ｔ Ｍ´ _ｕ Ｏ _２ ）中のＭｎの比率ｔの範囲を０．０５以上、０．５０以下とすることによって、第１のリチウム遷移金属複合酸化物及び第２のリチウム遷移金属複合酸化物中の各結晶構造が安定して高温環境下においても優れた充放電サイクル容量維持率が得られる。
【０１２８】
また、表４に示す評価結果から、実施例４及び実施例３３乃至実施例３６は、第１のリチウム遷移金属複合酸化物（Ｌｉ _ｘ Ｎｉ _{１−ｙ−ｚ} Ｃｏ _ｙ Ｍ _Ｚ Ｏ _２ ）中のＣｏの比率ｙ或いは第２のリチウム遷移金属複合酸化物（Ｌｉ _ｓ Ｎｉ _{１−ｔ−ｕ} Ｍｎ _ｔ Ｍ´ _ｕ Ｏ _２ ）中のＭｎの比率ｔの範囲を０．５０を超え、一方を０．０５以上、０．５０未満とした比較例１０乃至比較例１２と比べて、初期容量の高容量化が図られていることが分かる。
【０１２９】
比較例１０は、Ｃｏの比率ｙを０．６０とする第１のリチウム遷移金属複合酸化物であり、比較例１２は、Ｍｎの比率ｔを０．６０とする第２のリチウム遷移金属複合酸化物とした場合である。これら比較例１０乃至比較例１２のように、Ｃｏ及びＭｎの比率を０．５よりも大とすることにより、正極活物質全体の容量が低下したため初期容量が低下した。
【０１３０】
一方、実施例４及び実施例３３乃至実施例３６は、第１のリチウム遷移金属複合酸化物中のＣｏの比率ｙ及び第２のリチウム遷移金属複合酸化物中のＭｎの比率ｔの範囲を０．０５以上、０．５０以下にすることによって、結晶構造が安定して初期容量の高容量化が図られた。
【０１３１】
以上のように、非水電解質二次電池を作製する際には、第１のリチウム遷移金属複合酸化物中のＣｏ及び第２のリチウム遷移金属複合酸化物中のＭｎの比率を０．０５以上、０．５０以下の範囲とすることによって、初期容量の高容量化及び充放電サイクル特性の向上が図られることが分かった。
【０１３２】
【発明の効果】
以上、詳細に説明したように本発明によれば、高容量を有する第１の正極材料と、結晶構造が安定な第２の正極材料とを混合した混合物を含有する正極活物質を用いることによって、初期容量の高容量化及び高エネルギー密度の向上が図られ、常温に限らず高温環境下においても良好な充放電サイクル容量維持率を有する非水電解質二次電池を得ることができる。
【図面の簡単な説明】
【図１】本発明に係る非水電解質二次電池の縦断面図である。
【符号の説明】
１ 非水電解質二次電池、２ 正極、３ 負極、４ セパレータ、５ 電池缶、６ 絶縁板、７ 正極リード、８ 電流遮断用薄板、９ 電池蓋、１０ 負極リード、１１ 絶縁封口ガスケット、１２ センターピン、１３ 安全弁、１４ ＰＴＣ素子[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a positive electrode active material used for a battery and a nonaqueous electrolyte secondary battery using the positive electrode active material.
[0002]
[Prior art]
  In recent years, the demand for secondary batteries has been expanding rapidly with the appearance of many portable electronic devices such as camera-integrated VTRs, mobile phones, and laptop computers. With the reduction in size and weight of these electronic devices, secondary batteries are required to improve energy density as portable power sources. Among secondary batteries, a lithium ion secondary battery is expected because a large energy density can be obtained as compared with a lead battery and a nickel cadmium battery which are conventional aqueous electrolyte secondary batteries.
[0003]
  As lithium ion secondary batteries, lithium / cobalt composite oxides having a layered structure, lithium / manganese composite oxides having a spinel structure, lithium / nickel composite oxides, and the like have been put to practical use as positive electrode active materials.
[0004]
  Lithium-cobalt composite oxide has the best balance between physical properties such as charge capacity and thermal stability and cost, and is widely used. However, the lithium-cobalt composite oxide is expensive because the amount of cobalt mined is small. Therefore, a cheaper and higher capacity alternative material is required for the lithium-cobalt composite oxide. A spinel-structured lithium-manganese composite oxide has a lower charge capacity than other cobalt oxides and nickel oxides, and may have slightly poor high-temperature storage characteristics.
[0005]
  Lithium / nickel composite oxides are expected to be superior to lithium / cobalt composite oxides in terms of raw material prices and supply stability. However, since the lithium-nickel composite oxide has low crystal structure stability, there are problems such as a decrease in charge / discharge capacity and energy density, and deterioration of charge / discharge cycle characteristics in a high temperature environment. Therefore, the lithium / nickel composite oxide is excellent in terms of raw material price and supply stability as described above if the stability of the crystal structure can be achieved and the decrease in charge / discharge capacity and energy density can be suppressed. Therefore, it is a promising material in the future.
[0006]
  With respect to stabilization of the crystal structure of the lithium / nickel composite oxide, a method of solute substitution of a different element has been proposed. Further, a method has been proposed in which a lithium-nickel composite oxide is mixed with a spinel-structure lithium-manganese composite oxide that forms a stable crystal structure.
[0007]
[Problems to be solved by the invention]
  However, in order to meet the recent demands for higher density of electronic devices, higher speeds of integrated circuits, etc., or environmental resistance required for portable devices, it is more stable than the above-mentioned stabilization by solid solution replacement. It is necessary to form a crystal structure. In addition, the lithium-manganese composite oxide having a spinel structure has a stable crystal structure but has a low charge capacity, so the high capacity of the lithium-nickel composite oxide is not utilized and the charge / discharge capacity of the positive electrode is reduced. There's a problem.
[0008]
  Accordingly, the present invention has been proposed in view of such conventional circumstances, and is improved in charge / discharge capacity and energy density of the positive electrode, and also has good charge / discharge cycle characteristics not only at room temperature but also in a high temperature environment. It is an object of the present invention to provide a positive electrode active material obtained from the above and a nonaqueous electrolyte battery using the positive electrode active material.
[0009]
[Means for Solving the Problems]
  The positive electrode active material according to the present invention that achieves the above-described object isA first positive electrode material comprising a first lithium transition metal composite oxide having a layered structure represented by Formula 1; and a second positive electrode material comprising a second transition metal composite oxide having a layered structure represented by Formula 2. Characterized by having a mixture of.
[0010]
[Chemical formula 5]

[0011]
[Chemical 6]

[0012]
  The positive electrode active material as described above contains at least Ni and Co,Shown in Equation 1Layered structureThe first lithium transition metal composite oxideA first positive electrode material comprising: at least Ni and Mn;Shown in Equation 2Layered structureSecond lithium transition metal composite oxideThe first positive electrode material has a high capacity, and the second positive electrode material has a stable crystal structure. Therefore, the charge / discharge capacity is increased and the energy is increased. The density is improved, and good charge / discharge cycle characteristics can be obtained even in a high temperature environment.
[0013]
  The nonaqueous electrolyte secondary battery according to the present invention includes a positive electrode in which a positive electrode mixture layer containing a positive electrode active material is formed on a positive electrode current collector, and a negative electrode active material on the negative electrode current collector. A negative electrode formed with a negative electrode mixture layer and a non-aqueous electrolyte are provided. The positive electrode active material isA first positive electrode material comprising a first lithium transition metal composite oxide having a layered structure represented by the above formula 1 and a second positive electrode comprising a second transition metal composite oxide having a layered structure represented by the above formula 2. It is characterized by having a mixture with the material.
[0014]
  This non-aqueous electrolyte secondary battery contains at least Ni and Co,Shown in Equation 1Layered structureThe first lithium transition metal composite oxideA first positive electrode material comprising: at least Ni and Mn;Shown in Equation 2Layered structureSecond lithium transition metal composite oxideThe first positive electrode material has a high capacity by using a positive electrode active material containing a mixture obtained by mixing the second positive electrode material and the second positive electrode active material has a stable crystal structure. The charge / discharge capacity of the positive electrode is increased and the energy density is improved, and good charge / discharge cycle characteristics can be obtained even in a high temperature environment.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, a positive electrode active material and a nonaqueous electrolyte secondary battery using the positive electrode active material shown as embodiments of the present invention will be described in detail with reference to the drawings. As shown in FIG. 1, the nonaqueous electrolyte secondary battery 1 includes an electrode body in which a strip-like positive electrode 2 and a strip-like negative electrode 3 are wound in close contact with a separator 4 inside a battery can 5. Filled.
[0016]
  The positive electrode 2 is formed by applying a positive electrode mixture composed of a positive electrode active material, a binder, and a conductive agent on the positive electrode current collector in layers. As the binder, thermoplastic resins such as polytetrafluoroethylene, polyvinylidene fluoride, and polyethylene are used. Artificial graphite or carbon black is used as the conductive agent. Note that a metal foil such as an aluminum foil is used as the positive electrode current collector.
[0017]
  The positive electrode active material contains a mixture obtained by mixing the first positive electrode material and the second positive electrode material. The first positive electrode material has a layered structure and has a chemical formulaLi _x Ni _1-yz Co _y M _Z O ₂ (However, M is a transition metal or one element or a plurality of elements of Group 2, Group 3, and Group 4 of the periodic table of long-period elements)In seedsYes, the ranges of x, y, and z are 0.90 ≦ x <1.1, 0.05 ≦ y ≦ 0.50, and 0.01 ≦ z ≦ 0.10. Is a first lithium transition metal composite oxide. Chemical formulaLi _x Ni _1-yz Co _y M _Z O ₂ M in the figure specifically represents an element that can be uniformly dispersed in the crystal of the first lithium transition metal composite oxide, and particularly preferably Fe, Co, Zn, Al, Sn, Cr, V, Ti. From one or more of Mg, GaThe
[0018]
  The second positive electrode material has a layered structure and has a chemical formulaLi _s Ni _1-tu Mn _t M ' _u O ₂ (However, M ′ is a transition metal or one or more elements of Group 2, Group 3, and Group 4 of the periodic table of long-period elements)In seedsAnd s, t, and u are 0.90 ≦ s <1.1, 0.05 ≦ t ≦ 0.50, and 0.01 ≦ u ≦ 0.30, respectively. Is a second lithium transition metal composite oxide. Chemical formulaLi _s Ni _1-tu Mn _t M ' _u O ₂ M ′ therein specifically represents an element that can be uniformly dispersed in the crystal of the second lithium transition metal composite oxide, and particularly preferably Fe, Co, Zn, Al, Sn, Cr, V, , Ti, Mg, Ga from one or moreThe
[0019]
  The mixing ratio of the first lithium transition metal composite oxide and the second lithium transition metal composite oxide is preferably 15 wt% or more and 85 wt% or less with respect to the whole positive electrode active material, and more preferably 30 wt%. It is made to contain 70 to 70 weight%. In the positive electrode active material, when the mixing ratio of the first lithium transition metal composite oxide is less than 15% by weight, the mixing ratio of the second lithium transition metal composite oxide is 85.weight%, The proportion of the second lithium transition composite oxide having a low capacity with respect to the whole positive electrode active material is increased, and the high capacity of the first lithium transition metal composite oxide is not utilized and the initial capacity of the positive electrode active material is increased. Will fall. When the mixing ratio of the first lithium transition metal composite oxide exceeds 85% by weight, the mixing ratio of the second lithium transition composite oxide is 15weightSince the crystal structure of the positive electrode active material becomes unstable, the deterioration of the crystal structure progresses every time charging / discharging is repeated, and the charge / discharge cycle capacity maintenance rate under a high temperature environment is remarkably lowered.
[0020]
  Therefore, the positive electrode active material is charged by mixing the mixing ratio of each of the first lithium transition metal composite oxide and the second lithium transition metal composite oxide in the range of 15 wt% or more and 85 wt%. The first lithium transition metal composite oxide and the second lithium transition metal composite oxide cancel each other out with respect to the change in the crystal structure accompanying the discharge capacity and charge / discharge. The cycle capacity maintenance rate can be improved.
[0021]
  In the positive electrode active material, the average particle diameter of the first lithium transition metal composite oxide and the second lithium transition metal composite oxide is preferably 30 μm or less, more preferably 2 μm or more and 30 μm or less. The positive electrode active material has a large contact area between the positive electrode active material and the electrolyte when the average particle size of the first lithium transition metal composite oxide and the second lithium transition metal composite oxide is less than 2 μm. As the decomposition proceeds, the characteristics in a high temperature environment deteriorate. Conversely, when the average particle diameter of the first lithium transition metal composite oxide and the second lithium transition metal composite oxide exceeds 30 μm, the positive electrode active material and the first lithium transition metal composite oxide and the second lithium transition metal composite oxide Insufficient mixing with lithium transition metal composite oxide will cause a decrease in initial capacity and deterioration in charge / discharge cycle capacity maintenance rate under high temperature environment.
[0022]
  For this reason, in the positive electrode active material, the contact area between the positive electrode active material and the electrolytic solution is reduced by setting the average particle size of the first lithium transition metal composite oxide and the second lithium transition metal composite oxide to 30 μm or less. In addition, the first lithium transition metal composite oxide and the second lithium transition metal composite oxide are sufficiently mixed to increase the initial capacity and maintain the charge / discharge cycle capacity maintenance rate in a high temperature environment. Improvement is achieved.
[0023]
  Further, in the positive electrode active material, the ratio of Co in the first lithium transition metal composite oxide and the ratio of Mn in the second lithium transition metal composite oxide are preferably 0.05 or more and 0.50 or less. . In the positive electrode active material, when the ratio of Co and Mn is less than 0.05, the crystal structures of the first lithium transition metal composite oxide and the second lithium transition metal composite oxide become unstable, and charge and discharge are performed. Each time is repeated, the crystal structure of the positive electrode active material is deteriorated and the charge / discharge cycle characteristics are deteriorated. On the other hand, the positive electrode active material reduces the charge / discharge capacity because the ratio of Co and Mn is 0.50 or more to form a crystal structure that causes a decrease in charge / discharge capacity.
[0024]
  Therefore, the positive electrode active material is obtained by setting the ratio of Co in the first lithium transition metal composite oxide and the ratio of Mn in the second lithium transition metal composite oxide to 0.05 or more and 0.50 or less. Therefore, deterioration of the crystal structure is suppressed and charge / discharge cycle characteristics are improved.Ru. In addition, the positive electrode active material can have a high charge / discharge capacity by forming a high-capacity crystal structure by setting the ratio of Co and Mn to 0.05 or more and 0.50 or less.
[0025]
  In the first lithium transition metal composite oxide and the second lithium transition metal composite oxide, carbonates such as lithium, nickel, cobalt, and manganese are mixed according to each composition, and 600 to 600 in an air atmosphere or an oxygen atmosphere. It is obtained by firing in a temperature range of 1100 ° C. The starting material is not limited to carbonates, and can be similarly produced from hydroxides, oxides, nitrates, organic acid salts and the like. In addition, the first lithium transition metal composite oxide and the second lithium transition metal composite oxide can also use composite hydroxides, composite carbonates, etc. containing lithium, nickel, cobalt, manganese, etc. as raw materials. It is.
[0026]
  The positive electrode active material as described above is composed of a mixture of a high-capacity first lithium transition metal composite oxide and a second lithium transition metal composite oxide forming a stable crystal structure, The charge / discharge capacity can be increased and the crystal structure can be stabilized. Therefore, in the positive electrode active material, the charge / discharge capacity can be increased, the energy density can be increased, and the charge / discharge cycle capacity retention rate can be improved in a high temperature environment. Further, the positive electrode active material includes a mixing ratio of the first lithium transition metal composite oxide and the second lithium transition metal composite oxide, an average particle diameter, and Co and the first lithium transition metal composite oxide in the first lithium transition metal composite oxide. By defining the ratio of Mn in the lithium transition metal composite oxide 2 or the presence or absence of an additive element in the first lithium transition metal composite oxide and the second lithium transition metal composite oxide as described above, Better initial capacity and charge / discharge cycle capacity maintenance ratio can be obtained.
[0027]
  The negative electrode 3 is formed by applying a negative electrode mixture containing a negative electrode active material and a binder onto a negative electrode current collector. As the negative electrode active material, a material that can be electrochemically doped / undoped with lithium at a potential of lithium metal of 2.0 V or less is used. For example, non-graphitizable carbon, artificial graphite, natural graphite, pyrolytic carbons, cokes (pitch coke, needle coke, petroleum coke, etc.), graphites, glassy carbons, organic polymer compound fired bodies (phenolic resins) Carbonaceous materials such as those obtained by firing and carbonizing furan resin at an appropriate temperature), carbon fibers, activated carbon, carbon blacks and the like can be used.
[0028]
  In addition, as the negative electrode active material, a metal capable of forming an alloy with lithium and an alloy compound made of a metal capable of forming an alloy with lithium can be used. Examples of metals that can form an alloy with lithium include semiconductor elements such as Mg, B, Al, Ga, In, Si, Sn, Pb, Sb, Bi, Cd, Ag, Zn, Hf, Zr, and Y. It is. Furthermore, oxides such as ruthenium oxide, molybdenum oxide, tungsten oxide, titanium oxide, tin oxide, etc., which have a relatively low potential, and dope / dedope lithium ions, and other nitrides can be used as well. . Note that a metal such as a copper foil is used as the negative electrode current collector. Further, as the conductive agent, artificial graphite, carbon black or the like similar to the conductive agent used when the positive electrode 2 is manufactured is used.
[0029]
  The manufacturing method of the positive electrode 2 and the negative electrode 3 described above is a method in which a binder, a conductive agent and the like are added to the positive electrode active material and the negative electrode active material, and a solvent is added, and a binder and the like are added to the positive electrode active material and the negative electrode active material. Then, a method of applying by heating, a method of forming a molded body electrode by taking a treatment such as molding by mixing the positive electrode active material and the negative electrode active material alone or with a conductive agent and further a binder, etc. However, it is not limited to them.
[0030]
  For example, the method for producing the positive electrode 2 includes the above-described conductive agent and binder added to the positive electrode active material obtained by mixing the first lithium transition metal composite oxide and the second lithium transition metal composite oxide. A positive electrode mixture is prepared by mixing at a predetermined ratio, and the positive electrode mixture is dispersed in an organic solvent such as N-methyl-2-pyrrolidone to form a slurry. Next, the positive electrode mixture in the form of a slurry is uniformly applied on the positive electrode current collector to form a positive electrode mixture layer, dried, and molded to obtain the positive electrode 2.
[0031]
  Moreover, as a manufacturing method of the negative electrode 3, the negative electrode mixture which mixed the negative electrode active material and binder mentioned above in a predetermined ratio is made into a slurry form. Next, the negative electrode mixture in the form of a slurry is uniformly coated on the negative electrode current collector to form a negative electrode mixture layer, dried, and molded to obtain the negative electrode 3. In addition, in the manufacturing method of the positive electrode 2 and the negative electrode 3 mentioned above, the positive electrode 2 and the negative electrode 3 which have intensity | strength by pressure-molding with applying heat to a positive electrode active material and a negative electrode active material irrespective of the presence or absence of a binder. Can also be produced.
[0032]
  The method for producing the nonaqueous electrolyte secondary battery 1 using the positive electrode 2 and the negative electrode 3 described above is a production method in which the periphery of the core is wound via the separator 4 between the positive electrode 2 and the negative electrode 3, or the positive electrode For example, there is a lamination method in which the separator 4 is sandwiched between the anode 2 and the anode 3 and the cathode 2 and the anode 3 are laminated.
[0033]
  For the electrolyte, a matrix polymer is impregnated with a nonaqueous electrolytic solution obtained by dissolving an electrolyte salt in a nonaqueous solvent, a solid electrolyte containing an electrolyte salt, or a nonaqueous electrolytic solution composed of a nonaqueous solvent and an electrolyte salt. Any gelled electrolyte can be used.
[0034]
  The nonaqueous electrolytic solution is prepared by appropriately combining an organic solvent and an electrolyte salt. Any organic solvent may be used as long as it is used in a non-aqueous electrolyte battery. Examples of the organic solvent include propylene carbonate, ethylene carbonate, vinylene carbonate, diethyl carbonate, dimethyl carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, tetravidrofuran, 2-methyltetrahydrofuran, Examples include 1,3-dioxolane, 4 methyl 1,3 dioxolane, diethyl ether, sulfolane, methyl sulfolane, acetonitrile, propionitrile, anisole, acetate ester, butyrate ester, propionate ester and the like. Any electrolyte salt can be used as long as it is used for a non-aqueous electrolyte battery. Examples thereof include LiClO, LiAsF, LiPF, LiBF, LiB (CH), CHSOLi, CFSOLi, LiCl, and LiBr. is there.
[0035]
  As the solid electrolyte, either an inorganic solid electrolyte or a polymer solid electrolyte is used as long as the material has lithium ion conductivity. Examples of the inorganic solid electrolyte include lithium nitride and lithium iodide. The polymer solid electrolyte is composed of a polymer compound containing the above-described electrolyte salt. As the polymer compound, polyethylene oxide, ether-based polymer such as a cross-linked product, polymethacrylate ester system and acrylate system can be used alone or copolymerized or mixed in the molecule.
[0036]
  As the matrix polymer of the gel electrolyte, various organic polymers can be used as long as they can be gelated by absorbing the non-aqueous electrolyte. Examples of the matrix polymer include fluorine-based polymers such as polyvinylidene fluoride and polyvinylidene fluoride-co-hexafluoropropylene, ether-based polymers such as polyethylene oxide and a cross-linked product, and polyacrylonitrile. In particular, it is desirable to use a fluorine-based polymer for the matrix polymer of the gel electrolyte from the viewpoint of redox stability. The matrix of the gel electrolyte is given ionic conductivity by containing an electrolyte salt in the non-aqueous electrolyte.
[0037]
  The cylindrical non-aqueous electrolyte secondary battery 1 is manufactured by first winding the positive electrode 2 and the negative electrode 3 manufactured as described above a number of times through a separator 4 made of a porous polyolefin film to form a spiral type. An electrode body is prepared. Insulating plates 6 are arranged on both the upper and lower surfaces of the spiral electrode body and are housed in an iron battery can 5 that has been subjected to nickel plating. In order to collect the current of the positive electrode 2, one end of the aluminum positive electrode lead 7 is led out from the positive electrode current collector, and the other end is welded to the current interrupting thin plate 8 and electrically connected to the battery lid 9. Further, in order to collect the negative electrode 3, one end of the nickel negative electrode lead 10 is led out from the negative electrode current collector, and the other end is welded to the bottom of the battery can 5.
[0038]
  Next, after injecting the prepared non-aqueous electrolyte into the battery can 5 in which the electrode body described above is incorporated, the battery lid 9 is fixed by caulking the battery can 5 via the insulating sealing gasket 11. In the nonaqueous electrolyte secondary battery 1, the center pin 12 connected to the positive electrode lead 7 and the negative electrode lead 10 is provided, and the internal pressure of the nonaqueous electrolyte secondary battery 1 is higher than a predetermined value. In this case, a safety valve 13 for venting the gas inside the nonaqueous electrolyte battery 1 and a PTC (positive temperture coefficient) element 14 for preventing a temperature rise inside the nonaqueous electrolyte secondary battery 1 are provided.
[0039]
  The non-aqueous electrolyte secondary battery configured as described above includes the second lithium that forms a stable crystal structure with the high-capacity first lithium transition metal composite oxide in the positive electrode active material that forms the positive electrode 2. By comprising a mixture in which the transition metal composite oxide is mixed, the charge / discharge capacity can be increased and the crystal structure can be stabilized. Therefore, the non-aqueous electrolyte secondary battery 1 can improve the charge / discharge cycle capacity maintenance rate under normal temperature and high temperature environments as well as increase the charge / discharge capacity and the high energy density.
[0040]
  Further, since the shape of the nonaqueous electrolyte secondary battery 1 is not particularly limited, various shapes such as a cylindrical shape, a square shape, a coin shape, a button shape, and a laminate seal shape can be used. It is effective to apply the present invention in a winding method. In that case, the inner diameter of the winding core is made to match the diameter of the portion with the largest curvature among the elliptical cores used in winding the battery.
[0041]
【Example】
  Examples and comparative examples of nonaqueous electrolyte secondary batteries using a positive electrode active material to which the present invention is applied will be specifically described below. Here, the shape of the non-aqueous electrolyte secondary battery is a cylindrical non-aqueous electrolyte secondary battery.
[0042]
  Example 1
  First, the 1st lithium transition metal complex oxide was produced as follows. Commercially available lithium hydroxide, nickel monoxide, and cobalt oxide were used as raw materials for the first lithium transition metal composite oxide. In the first lithium transition metal composite oxide, lithium hydroxide, nickel monoxide, and cobalt oxide were mixed in the following composition. In Example 1, one element or plural kinds of transition metals or elements of Group 2, Group 3, and Group 4 of the periodic tableConsist ofThe additive M was produced without adding it to the first lithium transition metal composite oxide. Therefore, the chemical formula of the first lithium transition metal composite oxideLi _x Ni _1-yz Co _y M _Z O ₂ Li, Ni, Co, M element ratio x, 1-yz, y, z of x = 1.02, 1-yz = 0.70, y = 0.30, z = 0 It mix | blended so that it might become.
[0043]
  Next, the first lithium transition metal composite oxide is obtained by firing a mixture of lithium hydroxide, nickel monoxide, and cobalt oxide in the above-described composition for 10 hours in an oxygen stream at 800 ° C. and then crushing. It is done. And as a result of analyzing the obtained powder with an atomic absorption spectrometer, the first lithium transition metal composite oxide has the chemical formula Li _1.02 Ni _0.70 Co _0.3 O ₂ It was confirmed that Moreover, as a result of measuring the average particle diameter of this powder by the laser analysis method, it was confirmed to be 15 μm. Further, as a result of X-ray diffraction measurement of this powder, the obtained diffraction pattern was LiNiO in 09-0063 of International Center for Diffraction Date (hereinafter ICDD). ₂ LiNiO is similar to the diffraction pattern of ₂ It was confirmed that the same layered structure was formed.
[0044]
  Next, a second lithium transition metal composite oxide was produced as follows. Commercially available lithium hydroxide, nickel monoxide, and manganese dioxide were used as raw materials for the second lithium transition metal composite oxide. As the second lithium transition metal composite oxide, lithium hydroxide, nickel monoxide, and manganese dioxide were mixed in the following composition. As in the case of the first lithium transition metal composite oxide, the second lithium transition metal composite oxide may be replaced with a transition metal or one of elements of Group 2, Group 3, and Group 4 of the long-period element periodic table. Elements or multiple speciesConsist ofThe additive M ′ was prepared without being added to the second lithium transition metal composite oxide. Chemical formula of the second lithium transition metal complex oxideLi _s Ni _1-tu Mn _t M ' _u O ₂ The ratio s, 1-tu, t, u of Li, Ni, Mn, M ′ elements of s = 1.02, 1-tu = 0.65, t = 0.35, u = 0 It mixed so that it might become.
[0045]
  Next, the second lithium transition metal composite oxide is a mixture of lithium hydroxide, nickel monoxide, and manganese dioxide so as to have the above-mentioned ratio, which is fired in an oxygen stream at 800 ° C. for 10 hours, and then pulverized. Was obtained. And as a result of analyzing the obtained powder with an atomic absorption analyzer, the chemical formula Li of the second lithium transition metal composite oxide _1.02 Ni _0.65 Mn _0.35 O ₂ It was confirmed that Moreover, as a result of measuring the average particle diameter of this powder by the laser analysis method, 15 μm was confirmed. Moreover, as a result of performing X-ray diffraction measurement of this powder, the obtained diffraction pattern was LiNiO in 09-0063 of ICDD. ₂ LiNiO is similar to the diffraction pattern of ₂ It was confirmed that the same layered structure was formed.
[0046]
  Next, a positive electrode was produced. First, the first lithium transition metal composite oxide and the second lithium transition metal composite oxide described above were mixed to produce a positive electrode active material. In the positive electrode active material, the mixing ratio of the first lithium transition metal composite oxide and the second lithium transition metal composite oxide is such that the first lithium transition metal composite oxide to the second lithium transition metal composite oxide = 50. It was prepared by mixing so as to be 50% by weight with respect to 50% by weight. Next, 86% by weight of a positive electrode active material obtained by mixing the first lithium transition metal composite oxide and the second lithium transition metal composite oxide, 10% by weight of graphite as a conductive agent, and polyvinylidene fluoride as a binder 4% by weight (hereinafter referred to as PVdF) was mixed and dispersed in an organic solvent N-methyl-2-pyrrolidone (hereinafter referred to as NMP) to obtain a slurry. Next, the slurry-like positive electrode mixture is uniformly applied to both sides of a 20 μm-thick belt-like aluminum foil to form a positive electrode mixture layer, dried, and then compressed by a roller press to obtain a belt-like positive electrode. It was.
[0047]
  Next, a negative electrode was produced. For the negative electrode, powdered artificial graphite was used as the negative electrode active material, and 90% by weight of artificial graphite was mixed with 10% by weight of PVdF and dispersed in NMP to obtain a slurry. The slurry-like negative electrode mixture was uniformly applied on both sides of a copper foil having a thickness of 10 μm to form a negative electrode mixture layer, dried, and then compressed with a roller press to obtain a negative electrode.
[0048]
  Next, a non-aqueous electrolyte was prepared. The non-aqueous electrolyte is a mixed solution in which the volume mixing ratio of ethylene carbonate and methyl ethyl carbonate is 1: 1, and the concentration is 1 mol / dm. ³ It was obtained by dissolving in a solvent LiPF so that
[0049]
  Next, a cylindrical nonaqueous electrolyte secondary battery was produced. First, the positive electrode and the negative electrode prepared as described above were wound many times through a separator made of a porous polyolefin film to prepare a spiral electrode body. Insulating plates were arranged on both the upper and lower surfaces of the spiral electrode body and housed in an iron battery can that had been subjected to nickel plating. In order to collect the positive electrode current, one end of the aluminum positive electrode lead is led out from the positive electrode current collector, and the other end is welded to the current blocking thin plate to electrically connect the battery lid through the current blocking thin plate. Connected. In order to collect the negative electrode, one end of the nickel negative electrode lead was led out from the negative electrode current collector, and the other end was welded to the bottom of the battery can.
[0050]
  Next, after injecting the prepared non-aqueous electrolyte into the battery can in which the electrode body described above is incorporated, the battery lid is fixed by caulking the battery can through an insulating sealing gasket, and the outer diameter is 18 mm. A cylindrical nonaqueous electrolyte secondary battery having a height of 65 mm was produced. In the non-aqueous electrolyte secondary battery, a center pin connected to the positive electrode lead and the negative electrode lead is provided, and when the pressure inside the non-aqueous electrolyte secondary battery becomes higher than a predetermined value, the non-aqueous electrolyte secondary battery A safety valve for venting the gas inside the electrolyte battery and a PTC (positive temperture coefficient) element for preventing a temperature rise inside the nonaqueous electrolyte secondary battery were provided.
[0051]
  Example 2
  In Example 2, as the raw material of the first lithium transition metal composite oxide, aluminum hydroxide is used in addition to lithium hydroxide, nickel monoxide, and cobalt oxide, and these raw materials are mixed in the following proportions. did. Formula Li of the first lithium transition metal complex oxide _x Ni _1-yz Co _y Al _z O ₂ Li, Ni, Co, Al element ratio x, 1-yz, y, z of x = 1.02, 1-yz = 0.70, y = 0.25, z = 0. In the same manner as in Example 1 except that the mixture was mixed so as to be 05, Li _1.02 Ni _0.70 Co _0.25 Al _0.05 O ₂ The first lithium transition metal composite oxide was prepared. And the nonaqueous electrolyte secondary battery was produced like Example 1 except having used this 1st lithium transition metal complex oxide.
[0052]
  Example 3
  In Example 3, as the raw material for the second lithium transition metal composite oxide, aluminum hydroxide was used in addition to lithium hydroxide, nickel monoxide, and cobalt oxide, and these raw materials were mixed in the following proportions: did. Chemical formula Li of the second lithium transition metal composite oxide _s Ni _1-tu Mn _t Al _u O ₂ Li, Ni, Mn, Al element ratio s, 1-tu, t, u of s = 1.02, 1-tu = 0.65, t = 0.30, u = 0.05 Except for blending and mixing so that _1.02 Ni _0.65 Mn _0.30 Al _0.05 O ₂ The second lithium transition metal composite oxide was prepared. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that the second lithium transition metal composite oxide was used.
[0053]
  Example 4
  In Example 4, the first lithium transition metal composite oxide was treated in the same manner as the first lithium transition metal composite oxide of Example 2, and the chemical formula Li _1.02 Ni _0.70 Co _0.25 Al _0.05 O ₂ The first lithium transition metal composite oxide was prepared. The second lithium transition metal composite oxide was prepared in the same manner as the second lithium transition metal composite oxide of Example 3 with the chemical formula Li _1.02 Ni _0.65 Mn _0.3 Al _0.05 O ₂ The second lithium transition metal composite oxide was prepared. A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 1 except that these first lithium transition metal composite oxide and second lithium transition metal composite oxide were used.
[0054]
  Example 5
  In Example 5, as the raw material of the first lithium transition metal composite oxide, in addition to lithium hydroxide, nickel monoxide, and cobalt oxide, iron hydroxide was used instead of aluminum hydroxide, and the first lithium transition metal composite oxide was used. Chemical formula of metal complex oxide Li _x Ni _1-yz Co _y Fe _Z O ₂ The ratio x, 1-yz, y, and z of Li, Ni, Co, and Fe elements of x = 1.02, 1-yz = 0.70, y = 0.25, z = 0. In the same manner as in Example 4 except that mixing was performed so as to be 05, Li _1.02 Ni _0.70 Co _0.25 Fe _0.05 O ₂ The first lithium transition metal composite oxide was prepared. A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this first lithium transition metal composite oxide was used.
[0055]
  Example 6
  In Example 6, as the raw material for the first lithium transition metal composite oxide, in addition to lithium hydroxide, nickel monoxide, and cobalt oxide, tin oxide was used instead of aluminum hydroxide, and the first lithium transition metal composite oxide was used. Formula Li _x Ni _1-yz Co _y Sn _Z O ₂ The ratio x, 1-yz, y, z of Li, Ni, Co, and Sn elements of x = 1.02, 1-yz = 0.70, y = 0.25, z = 0. In the same manner as in Example 4 except that mixing was performed so as to be 05, Li _1.02 Ni _0.70 Co _0.25 Sn _0.05 O ₂ The first lithium transition metal composite oxide was prepared. A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this first lithium transition metal composite oxide was used.
[0056]
  Example 7
  In Example 7, as the raw material of the first lithium transition metal composite oxide, in addition to lithium hydroxide, nickel monoxide, cobalt oxide, chromium oxide was used instead of aluminum hydroxide, and the first lithium transition metal composite oxide was used. Formula Li _x Ni _1-yz Co _y Cr _Z O ₂ Li, Ni, Cr, Al element ratio x, 1-yz, y, z of x = 1.02, 1-yz = 0.70, y = 0.25, z = 0. In the same manner as in Example 4 except that mixing was performed so as to be 05, Li _1.02 Ni _0.70 Co _0.25 Cr _0.05 O ₂ The first lithium transition metal composite oxide was prepared. A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this first lithium transition metal composite oxide was used.
[0057]
  Example 8
  In Example 8, as the raw material of the first lithium transition metal composite oxide, in addition to lithium hydroxide, nickel monoxide, and cobalt oxide, vanadium pentoxide was used instead of aluminum hydroxide, so that the first lithium transition Chemical formula of metal complex oxide Li _x Ni _1-yz Co _y V _Z O ₂ The ratio x, 1-yz, y, z of Li, Ni, Co, and V elements of x = 1.02, 1-yz = 0.70, y = 0.25, z = 0. In the same manner as in Example 4 except that mixing was performed so as to be 05, Li _1.02 Ni _0.70 Co _0.25 V _0.05 O ₂ The first lithium transition metal composite oxide was prepared. A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this first lithium transition metal composite oxide was used.
[0058]
  Example 9
  In Example 9, as the raw material of the first lithium transition metal composite oxide, in addition to lithium hydroxide, nickel monoxide, and cobalt oxide, titanium oxide was used instead of aluminum hydroxide, and the first lithium transition metal composite oxide was used. Formula Li _x Ni _1-yz Co _y Ti _Z O ₂ The ratio x, 1-yz, y, z of Li, Ni, Co, and Ti elements of x = 1.02, 1-yz = 0.70, y = 0.25, z = 0. In the same manner as in Example 4 except that mixing was performed so as to be 05, Li _1.02 Ni _0.70 Co _0.25 Ti _0.05 O ₂ The first lithium transition metal composite oxide was prepared. A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this first lithium transition metal composite oxide was used.
[0059]
  Example 10
  In Example 10, as a raw material of the first lithium transition metal composite oxide, in addition to lithium hydroxide, nickel monoxide, and cobalt oxide, magnesium oxide was used instead of aluminum hydroxide, and the first lithium transition metal composite oxide was used. Formula Li _x Ni _1-yz Co _y Mg _Z O ₂ The ratio x, 1-yz, y, z of Li, Ni, Co, and Mg elements is x = 1.02, 1-yz = 0.70, y = 0.25, z = 0. In the same manner as in Example 4 except that mixing was performed so as to be 05, Li _1.02 Ni _0.70 Co _0.25 Mg _0.05 O ₂ The first lithium transition metal composite oxide was prepared. A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this first lithium transition metal composite oxide was used.
[0060]
  Example 11
  In Example 11, as the raw material of the first lithium transition metal composite oxide, in addition to lithium hydroxide, nickel monoxide, and cobalt oxide, gallium nitrate was used instead of aluminum hydroxide, and the first lithium transition metal composite oxide was used. Formula Li _x Ni _1-yz Co _y Ga _Z O ₂ The ratio x, 1-yz, y, and z of Li, Ni, Co, and Ga elements of x = 1.02, 1-yz = 0.70, y = 0.25, z = 0. In the same manner as in Example 4 except that mixing was performed so as to be 05, Li _1.02 Ni _0.70 Co _0.25 Ga _0.05 O ₂ The first lithium transition metal composite oxide was prepared. A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this first lithium transition metal composite oxide was used.
[0061]
  Example 12
  In Example 12, as the raw material of the second lithium transition metal composite oxide, in addition to lithium hydroxide, nickel monoxide, and cobalt oxide, iron hydroxide was used instead of aluminum hydroxide, and the second lithium transition metal composite oxide was used. Chemical formula of metal complex oxide Li _s Ni _1-tu Mn _t Fe _u O ₂ Li, Ni, Mn, Fe element ratio s, 1-tu, t, u of s = 1.02, 1-tu = 0.65, t = 0.30, u = 0.05 Except for blending and mixing so that _1.02 Ni _0.65 Mn _0.30 Fe _0.05 O ₂ The second lithium transition metal composite oxide was prepared. A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this first lithium transition metal composite oxide was used.
[0062]
  Example 13
  In Example 13, as the raw material of the second lithium transition metal composite oxide, in addition to lithium hydroxide, nickel monoxide, and cobalt oxide, cobalt oxide was used instead of aluminum hydroxide, and the second lithium transition metal composite oxide was used. Formula Li _s Ni _1-tu Mn _t Co _u O ₂ Li, Ni, Mn, Co element ratio s, 1-tu, t, u of s = 1.02, 1-tu = 0.65, t = 0.30, u = 0.05 Except for blending and mixing so that _1.02 Ni _0.65 Mn _0.30 Co _0.05 O ₂ The second lithium transition metal composite oxide was prepared. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this second lithium transition metal composite oxide was used.
[0063]
  Example 14
  In Example 14, as the raw material of the second lithium transition metal composite oxide, in addition to lithium hydroxide, nickel monoxide, and cobalt oxide, zinc hydroxide was used instead of aluminum hydroxide, and the second lithium transition metal composite oxide was used. Chemical formula of metal complex oxide Li _s Ni _1-tu Mn _t Zn _u O ₂ Li, Ni, Mn, Zn element ratio s, 1-tu, t, u are s = 1.02, 1-tu = 0.65, t = 0.30, u = 0.05 Except for blending and mixing so that _1.02 Ni _0.65 Mn _0.30 Zn _0.05 O ₂ The second lithium transition metal composite oxide was prepared. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this second lithium transition metal composite oxide was used.
[0064]
  Example 15
  In Example 15, as the raw material of the second lithium transition metal composite oxide, in addition to lithium hydroxide, nickel monoxide, and cobalt oxide, tin oxide was used instead of aluminum hydroxide, and the second lithium transition metal composite oxide was used. Formula Li _s Ni _1-tu Mn _t Sn _u O ₂ Li, Ni, Mn, Sn element ratio s, 1-tu, t, u of s = 1.02, 1-tu = 0.65, t = 0.30, u = 0.05 Except for blending and mixing so that _1.02 Ni _0.65 Mn _0.30 Sn _0.05 O ₂ The second lithium transition metal composite oxide was prepared. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this second lithium transition metal composite oxide was used.
[0065]
  Example 16
  In Example 16, as the raw material of the second lithium transition metal composite oxide, in addition to lithium hydroxide, nickel monoxide, and cobalt oxide, chromium oxide was used instead of aluminum hydroxide, so that the second lithium transition metal Formula Li _s Ni _1-tu Mn _t Cr _u O ₂ The ratio of Li, Ni, Mn, and Cr elements of s, 1-tu, t, u is s = 1.02, 1-tu = 0.65, t = 0.30, u = 0.05 Except for blending and mixing so that _1.02 Ni _0.65 Mn _0.30 Cr _0.05 O ₂ The second lithium transition metal composite oxide was prepared. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this second lithium transition metal composite oxide was used.
[0066]
  Example 17
  Example 17 uses lithium hydroxide, nickel monoxide, cobalt oxide as a raw material for the second lithium transition metal composite oxide, and uses vanadium pentoxide instead of aluminum hydroxide to produce the second lithium transition metal oxide. Chemical formula of metal complex oxide Li _s Ni _1-tu Mn _t V _u O ₂ Li, Ni, Mn,VThe element ratios s, 1-tu, t, and u were mixed and mixed so that s = 1.02, 1-tu = 0.65, t = 0.30, and u = 0.05. Except for the same as Example 4, Li _1.02 Ni _0.65 Mn _0.30 V _0.05 O ₂ The second lithium transition metal composite oxide was prepared. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this second lithium transition metal composite oxide was used.
[0067]
  Example 18
  In Example 18, as the raw material of the second lithium transition metal composite oxide, in addition to lithium hydroxide, nickel monoxide, and cobalt oxide, titanium oxide was used instead of aluminum hydroxide, and the second lithium transition metal composite oxide was used. Formula Li _s Ni _1-tu Mn _t Ti _u O ₂ Li, Ni, Mn, Ti element ratio s, 1-tu, t, u are s = 1.02, 1-tu = 0.65, t = 0.30, u = 0.05 Except for blending and mixing so that _1.02 Ni _0.65 Mn _0.30 Ti _0.05 O ₂ The second lithium transition metal composite oxide was prepared. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this second lithium transition metal composite oxide was used.
[0068]
  Example 19
  Example 19 uses lithium oxide, nickel monoxide, cobalt oxide as a raw material for the second lithium transition metal composite oxide, and magnesium oxide instead of aluminum hydroxide. Formula Li _s Ni _1-tu Mn _t Mg _u O ₂ Li, Ni, Mn, Mg element ratio s, 1-tu, t, u are s = 1.02, 1-tu = 0.65, t = 0.30, u = 0.05 Except for blending and mixing so that _1.02 Ni _0.65 Mn _0.30 Mg _0.05 O ₂ The second lithium transition metal composite oxide was prepared. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this second lithium transition metal composite oxide was used.
[0069]
  Example 20
  In Example 20, as the raw material of the second lithium transition metal composite oxide, in addition to lithium hydroxide, nickel monoxide, and cobalt oxide, gallium nitrate was used instead of aluminum hydroxide, so that the second lithium transition metal Formula Li _s Ni _1-tu Mn _t Ga _u O ₂ Li, Ni, Mn, Ga element ratio s, 1-tu, t, u are s = 1.02, 1-tu = 0.65, t = 0.30, u = 0.05 Except for blending and mixing so that _1.02 Ni _0.65 Mn _0.30 Ga _0.05 O ₂ The second lithium transition metal composite oxide was prepared. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this second lithium transition metal composite oxide was used.
[0070]
  Example 21
  In Example 21, the mixing ratio of the first lithium transition metal composite oxide and the second lithium transition metal composite oxide was changed to the first lithium transition metal composite oxide: second lithium transition metal composite oxide = 15 weight. %: A positive electrode active material was produced in the same manner as in Example 4 except that mixing was performed at 85% by weight. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this positive electrode active material was used.
[0071]
  Example 22
  In Example 22, the mixing ratio of the first lithium transition metal composite oxide and the second lithium transition metal composite oxide was changed to the first lithium transition metal composite oxide: second lithium transition metal composite oxide = 30 weight. %: A positive electrode active material was produced in the same manner as in Example 4 except that mixing was performed so as to be 70% by weight. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this positive electrode active material was used.
[0072]
  Example 23
  In Example 23, the mixing ratio of the first lithium transition metal composite oxide and the second lithium transition metal composite oxide was changed to the first lithium transition metal composite oxide: second lithium transition metal composite oxide = 70 weight. %: A positive electrode active material was produced in the same manner as in Example 4 except that mixing was performed so as to be 30% by weight. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this positive electrode active material was used.
[0073]
  Example 24
  In Example 24, the mixing ratio of the first lithium transition metal composite oxide and the second lithium transition metal composite oxide was changed to the first lithium transition metal composite oxide: second lithium transition metal composite oxide = 85 weight. %: A positive electrode active material was produced in the same manner as in Example 4 except that mixing was performed so as to be 15% by weight. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this positive electrode active material was used.
[0074]
  Example 25
  In Example 25, the first lithium transition metal composite oxide was prepared in the same manner as in Example 4 except that the production conditions were changed, and the first lithium transition metal composite oxide having an average average particle size of 2 μm was produced. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this first lithium transition metal composite oxide was used.
[0075]
  Example 26
  In Example 26, the first lithium transition metal composite oxide was prepared in the same manner as in Example 4 except that the preparation conditions were changed, and the first lithium transition metal composite oxide having an average average particle size of 8 μm was prepared. A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this first lithium transition metal composite oxide was used.
[0076]
  Example 27
  In Example 27, the first lithium transition metal composite oxide was produced in the same manner as in Example 4 except that the production conditions were changed and the first lithium transition metal composite oxide having an average average particle size of 20 μm was produced. . A nonaqueous electrolyte secondary battery was fabricated in the same manner as in Example 4 except for this.
[0077]
  Example 28
  In Example 28, the first lithium transition metal composite oxide having an average average particle size of 30 μm was prepared in the same manner as in Example 4 by changing the preparation conditions of the first lithium transition metal composite oxide. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this first lithium transition metal composite oxide was used.
[0078]
  Example 29
  In Example 29, the production conditions of the second lithium transition metal composite oxide in Example 4 were changed, and the second lithium transition metal composite oxide having an average particle diameter of 2 μm was used as the second lithium transition metal composite of Example 4. It was produced in the same manner as the complex oxide. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this second lithium transition metal composite oxide was used.
[0079]
  Example 30
  In Example 30, the second lithium transition metal composite oxide of Example 4 was replaced with the second lithium transition metal composite oxide having an average average particle size of 9 μm by changing the preparation conditions of the second lithium transition metal composite oxide. It produced similarly. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this second lithium transition metal composite oxide was used.
[0080]
  Example 31
  In Example 31, the second lithium transition metal composite oxide of Example 4 was replaced with the second lithium transition metal composite oxide having an average average particle diameter of 18 μm by changing the production conditions of the second lithium transition metal composite oxide. It produced similarly. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this second lithium transition metal composite oxide was used.
[0081]
  Example 32
  In Example 32, the preparation conditions of the second lithium transition metal composite oxide were changed, and the second lithium transition metal composite oxide having an average particle size of 30 μm was changed to the second lithium transition metal composite oxide of Example 4. It produced similarly. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this second lithium transition metal composite oxide was used.
[0082]
  Example 33
  In Example 33, the composition y of the Li, Ni, Co, and Al elements in the first lithium transition metal composite oxide was changed to 0.05 for the composition ratio y of cobalt in the first lithium transition metal composite oxide. So that the ratio x, 1-yz, y, z is x = 1.02, 1-yz = 0.90, y = 0.05, z = 0.05, A first lithium transition metal composite oxide was produced. A nonaqueous electrolyte secondary battery was fabricated in the same manner as in Example 4 except for this.
[0083]
  Example 34
  In Example 34, the composition ratio y of cobalt in the first lithium transition metal composite oxide was changed to 0.50, and the composition ratio x, 1-yz, of Li, Ni, Co, and Al elements was changed. The first lithium transition metal composite oxide is mixed by mixing so that y and z are x = 1.02, 1-yz = 0.45, y = 0.50, and z = 0.05. It was produced in the same manner as the first lithium transition metal composite oxide of Example 4. A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this first lithium transition metal composite oxide was used.
[0084]
  Example 35
  In Example 35, the composition ratio t of manganese in the second lithium transition metal composite oxide was changed to 0.05, the composition ratio s of Li, Ni, Mn, and Al elements s, 1-tu, t, u are mixed so that s = 1.02, 1-tu = 0.90, t = 0.05, u = 0.05, and the second lithium transition metal composite oxide is obtained. It was produced in the same manner as the second lithium transition metal composite oxide of Example 4. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this second lithium transition metal composite oxide was used.
[0085]
  Example 36
  In Example 36, the composition of Li, Ni, Mn, and Al elements in the second lithium transition metal composite oxide was changed by changing the manganese composition ratio t in the second lithium transition metal composite oxide to 0.50. So that the ratio of s, 1-tu, t, u is s = 1.02, 1-tu = 0.45, t = 0.50, u = 0.05. A second lithium transition metal composite oxide was produced in the same manner as in Example 4. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this second lithium transition metal composite oxide was used.
[0086]
  Comparative Example 1
  In Comparative Example 1, lithium hydroxide, nickel monoxide, and cobalt oxide were mixed as raw materials for the first lithium transition metal composite oxide in the following composition. Chemical formula of the first lithium transition metal composite oxideLi _x Ni _1-yz Co _y M _Z O ₂ Li, Ni, Co, M element ratio x, 1-yz, y, z of x = 1.02, 1-yz = 0.70, y = 0.30, z = 0 It mix | blended so that it might become. The first lithium transition metal composite oxide has the chemical formula Li _1.02 Ni _0.70 Co _0.30 O ₂ This was prepared in the same manner as the first lithium transition metal composite oxide of Example 4. In Comparative Example 1, a positive electrode active material was prepared by using the first lithium transition metal composite oxide alone without using the second lithium transition metal composite oxide. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this positive electrode active material was used.
[0087]
  Comparative Example 2
  In Comparative Example 2, commercially available lithium hydroxide, nickel monoxide, and manganese dioxide were used as raw materials for the second lithium transition metal composite oxide. The second lithium transition metal composite oxide has the chemical formula Li _1.02 Ni _0.7 Mn _0.3 O ₂ A first lithium transition metal composite oxide represented by the following formula was prepared in the same manner as in Example 4. In Comparative Example 2, a positive electrode active material was prepared by using the second lithium transition metal composite oxide alone without using the first lithium transition composite oxide. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this positive electrode active material was used.
[0088]
  Comparative Example 3
  In Comparative Example 3, the mixing ratio of the first lithium transition metal composite oxide and the second lithium transition metal composite oxide was determined as follows: first lithium transition metal composite oxide: second lithium transition metal composite oxide = 10 % By weight: A positive electrode active material was prepared in the same manner as in Example 4 except that mixing was performed at 90% by weight. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this positive electrode active material was used.
[0089]
  Comparative Example 4
  In Comparative Example 4, the mixing ratio of the first lithium transition metal composite oxide and the second lithium transition metal composite oxide was determined as follows: first lithium transition metal composite oxide: second lithium transition metal composite oxide = 90 % By weight: A positive electrode active material was prepared in the same manner as in Example 4 except that mixing was performed at 10% by weight. A nonaqueous electrolyte secondary battery was fabricated in the same manner as in Example 4 except for the above.
[0090]
  Comparative Example 5
  In Comparative Example 5, the first lithium transition metal composite oxide having an average particle diameter of 1 μm was prepared in the same manner as in Example 4 by changing the preparation conditions of the first lithium transition metal composite oxide. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this first lithium transition metal composite oxide was used.
[0091]
  Comparative Example 6
  In Comparative Example 6, the first lithium transition metal composite oxide having an average particle size of 40 μm was prepared in the same manner as in Example 4 by changing the preparation conditions of the first lithium transition metal composite oxide. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this first lithium transition metal composite oxide was used.
[0092]
  Comparative Example 7
  In Comparative Example 7, the second lithium transition metal composite oxide having an average particle diameter of 1 μm was prepared in the same manner as in Example 4 by changing the preparation conditions of the second lithium transition metal composite oxide. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this second lithium transition metal composite oxide was used.
[0093]
  Comparative Example 8
  In Comparative Example 8, a second lithium transition metal composite oxide having an average particle size of 40 μm was prepared in the same manner as in Example 4 by changing the preparation conditions of the second lithium transition metal composite oxide. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this second lithium transition metal composite oxide was used.
[0094]
  Comparative Example 9
  In Comparative Example 9, the composition ratio y of cobalt in the first lithium transition metal composite oxide was changed to 0.01, and the composition ratios x, 1-yz, Li, Ni, Co, and Al elements were changed. y and z are x = 1.02, 1-yz = 0.94The first lithium transition metal composite oxide was prepared in the same manner as the first lithium transition metal composite oxide of Example 4 by mixing so that y = 0.01 and z = 0.05. A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this first lithium transition metal composite oxide was used.
[0095]
  Comparative Example 10
  In Comparative Example 10, the composition ratio y of cobalt in the first lithium transition metal composite oxide was changed to 0.60, the composition ratios x, 1-yz, Li, Ni, Co, and Al elements y and z are x = 1.02, 1-yz = 0.35The first lithium transition metal composite oxide was prepared in the same manner as the first lithium transition metal composite oxide of Example 4 by mixing so that y = 0.60 and z = 0.05. A non-aqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this first lithium transition metal composite oxide was used.
[0096]
  Comparative Example 11
  In Comparative Example 11, the composition ratio t of manganese in the second lithium transition metal composite oxide was changed to 0.01, the composition ratio s of Li, Ni, Mn, and Al elements s, 1-tu, t and u are s = 1.02, 1-tu = 0.94, T = 0.01, and u = 0.05, and the second lithium transition metal composite oxide was produced in the same manner as the second lithium transition metal composite oxide of Example 4. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this second lithium transition metal composite oxide was used.
[0097]
  Comparative Example 12
  In Comparative Example 12, the composition ratio t of manganese in the second lithium transition metal composite oxide was changed to 0.60, the composition ratio s of Li, Ni, Mn, and Al elements, 1-tu, t and u are s = 1.02, 1-tu = 0.35, T = 0.60, and u = 0.05, and the second lithium transition metal composite oxide was produced in the same manner as the second lithium transition metal composite oxide of Example 4. A nonaqueous electrolyte secondary battery was produced in the same manner as in Example 4 except that this second lithium transition metal composite oxide was used.
[0098]
  Next, the non-aqueous electrolyte secondary batteries of Examples and Comparative Examples manufactured as described above were charged under the conditions of an environmental temperature of 23 ° C., a charging voltage of 4.20 V, a charging current of 1000 mA, and a charging time of 2.5 hours. Thereafter, the battery was discharged at a charging current of 1500 mA and a final voltage of 2.75 V, and the initial capacity was measured. Furthermore, charging / discharging was repeated under the same conditions, the discharge capacity at the 100th cycle at 23 ° C. was measured, and the capacity retention rate at the 100th cycle with respect to the initial capacity was determined. In addition, the capacity maintenance rate at the 100th cycle was measured when charging / discharging at 50 ° C. was repeated in the same manner as when the environmental temperature was set to 50 ° C. and the other conditions were 23 ° C. .
[0099]
  Table 1 shows the evaluation results of the initial capacity in Examples 1 to 20, Comparative Example 1 and Comparative Example 2, the 100 cycle capacity retention at 23 ° C., and the 100 cycle capacity retention at 50 ° C.
[0100]
[Table 1]

[0101]
  From the evaluation results shown in Table 1, in Examples 1 to 20 in which a mixture obtained by mixing the first lithium transition metal composite oxide and the second lithium transition metal composite oxide was used as the positive electrode active material, It can be seen that, compared with Comparative Example 1 in which the positive electrode active material is formed solely from the lithium transition metal composite oxide, the 100 cycle capacity retention rate at 23 ° C. and 50 ° C. is improved.
[0102]
  Comparative Example 1 is a case where the first lithium transition metal composite oxide is used alone as the positive electrode active material, and one of the transition metals or elements of Group 2, Group 3, and Group 4 of the Periodic Table of Elements or Multiple speciesWhat consists ofSince the crystal structure is not added, the crystal structure is unstable, so that the crystal structure deteriorates every time charge and discharge are repeated. Therefore, when the first lithium transition metal composite oxide is used alone as the positive electrode active material, the charge / discharge cycle capacity retention rate is reduced. In particular, the charge / discharge cycle capacity retention rate in a high-temperature environment is accelerated by deterioration of the crystal structure at high temperatures, and is further significantly reduced by decomposition of the electrolyte.
[0103]
  On the other hand, in Examples 1 to 20, the crystal structure of the second lithium transition metal composite oxide was obtained by mixing the second lithium transition metal composite oxide in addition to the first lithium transition metal composite oxide. Therefore, the change in the crystal structure of the positive electrode active material associated with charge / discharge is reduced, and the deterioration of the crystal structure of the entire positive electrode active material associated with charge / discharge is suppressed. For this reason, the positive electrode active material has an improved 100 cycle capacity retention rate at 23 ° C. and 50 ° C.
[0104]
  In addition, from the evaluation results shown in Table 1, in Examples 1 to 20, the initial capacity was higher than that in Comparative Example 2 in which the second lithium transition metal composite oxide alone was formed as the positive electrode active material. It can be seen that the capacity is increased.
[0105]
  In Comparative Example 2, the second lithium transition metal composite oxide is used alone as the positive electrode active material, and one of the transition metals or the elements of Groups 2, 3, and 4 of the Periodic Table of Elements or Multiple speciesWhat consists ofSince the second lithium transition metal composite oxide has a low capacity because it is not added, the initial capacity is lowered.
[0106]
  On the other hand, in Example 1 to Example 20, the first lithium transition metal composite oxide has a high capacity by mixing the first lithium transition metal composite oxide in addition to the second lithium transition metal composite oxide. Therefore, the initial capacity of the whole positive electrode active material is improved.
[0107]
  From the above, when producing a nonaqueous electrolyte secondary battery, by using a mixture in which the first lithium transition metal composite oxide and the second lithium transition metal composite oxide are mixed in the positive electrode active material, It is clear that it is effective for increasing the initial capacity, increasing the energy density, and improving the charge / discharge cycle capacity retention rate. In addition, as in Example 1, the first lithium transition metal composite oxide and the second lithium transition metal composite oxide are selected from transition metals or groups 2, 3, and 4 of the periodic table. Even without adding an element, it is possible to increase the initial capacity and improve the charge / discharge cycle capacity retention rate.
[0108]
  Next, the example4Table 2 shows the evaluation results of the initial capacity in Examples 21 to 24, Comparative Example 3 and Comparative Example 4, the 100 cycle capacity retention at 23 ° C., and the 100 cycle capacity retention at 50 ° C. Note that the additive M and the additive M ′ added to the first lithium transition metal composite oxide and the second lithium transition metal composite oxide are described in Examples.4Examples 21 to 24, Comparative Example 3 and Comparative Example 4 are all Al.
[0109]
[Table 2]

[0110]
  Based on the evaluation results shown in Table 2, the mixing ratio of the first lithium transition metal composite oxide and the second lithium transition metal composite oxide was set to 15% by weight or more and 85% by weight or less based on the entire positive electrode active material. In Example 1 and Examples 21 to 24, the initial capacity was higher than that in Comparative Example 3 in which the first lithium transition metal composite oxide was 10% and the second lithium transition metal composite oxide was 90%. It can be seen that the capacity is increased.
[0111]
  In Comparative Example 3, a mixture obtained by mixing 10% by weight of the first lithium transition metal composite oxide and 90% by weight of the second lithium transition metal composite oxide with respect to the whole positive electrode active material was used as the positive electrode active material. The low-capacity second lithium transition metal composite oxide occupies most of the positive electrode active material.4Also, the initial capacity is remarkably reduced as compared with Examples 21 to 24.
[0112]
  On the other hand, Example4In Examples 21 to 24, the mixing ratio of the second lithium transition metal composite oxide with respect to the whole positive electrode active material is mixed in the range of 15 wt% or more and 85 wt% or less, thereby increasing the capacity. Since the first lithium transition metal composite oxide is contained in an appropriate weight% with respect to the whole positive electrode active material, the capacity of the initial capacity is increased. In Example 1 and Examples 21 to 24, the initial capacity is increased as the mixing ratio of the first lithium transition metal composite oxide increases.
[0113]
  Moreover, from the evaluation results shown in Table 2, the examples4In Examples 21 to 24, the first lithium transition metal composite oxide was 90%, and the second lithium transition metal composite oxide was 10%. It can be seen that the cycle capacity retention rate is improved.
[0114]
  In Comparative Example 4, the mixture of 90% of the first lithium transition metal composite oxide and 10% of the second lithium transition metal composite oxide with respect to the whole positive electrode active material was used as a positive electrode active material, Since the first lithium transition metal composite oxide having an unstable structure occupies most of the positive electrode active material, the deterioration of the crystal structure is promoted every time charging and discharging are repeated, and the charge / discharge cycle capacity maintenance rate is reduced. Yes. In particular, in the positive electrode active material, the deterioration of the crystal structure is accelerated under a high temperature environment, and the capacity maintenance rate of 100 cycles at 50 ° C. is remarkably lowered with the deterioration of the electrolyte.
[0115]
  On the other hand, Example4In Examples 21 to 24, the mixing ratio of the first lithium transition metal composite oxide is mixed in the range of 15 wt% or more and 85 wt% or less with respect to the entire positive electrode active material. By mixing at an appropriate weight%, the change in the crystal structure of the positive electrode active material accompanying charge / discharge is suppressed, and the charge / discharge cycle capacity retention rate is improved.
[0116]
  From the above, the positive electrode active material has a mixing ratio of the first lithium transition metal composite oxide in the range of 15% by weight or more and 85% by weight or less with respect to the whole when producing the nonaqueous electrolyte secondary battery. It can be seen that mixing at the above can increase the initial capacity and improve the charge / discharge cycle capacity retention rate.
[0117]
  Next, the example4Table 3 shows the evaluation results of the initial capacities in Examples 27 to 32 and Comparative Examples 5 to 8, the 100 cycle capacity retention at 23 ° C., and the 100 cycle capacity retention at 50 ° C. The mixing ratio of the first lithium transition metal composite oxide and the second lithium transition metal composite oxide is as follows: first lithium transition metal composite oxide: second lithium transition metal composite oxide = 50 wt% : 50% by weight.
[0118]
[Table 3]

[0119]
  From the evaluation results shown in Table 3, the average particle diameter of each of the first lithium transition metal composite oxide and the second lithium transition metal composite oxide was set in the range of 2 μm to 30 μm.4Examples 27 to 32 and Comparative Example 5 to Comparative Example in which one of the first lithium transition metal composite oxide or the second lithium transition metal composite oxide was 1 μm or 40 μm and the other was 15 μm 8 and 50, it can be seen that the 50 ° C. and 100 cycle capacity retention rate is improved.
[0120]
  In Comparative Examples 5 to 8, when the average particle diameter of either the first lithium transition metal composite oxide or the second lithium transition metal composite oxide is less than 2 μm and the other is 15 μm, the positive electrode active material Since the contact area with the electrolytic solution becomes too large, the decomposition of the electrolyte proceeds and the examples4Compared with Example 27 thru | or Example 32, the cycle capacity maintenance factor in 50 degreeC is falling. On the other hand, if the average particle size exceeds 30 μm, the mixing of the first lithium transition metal composite oxide and the second lithium transition metal composite oxide becomes insufficient, and the cycle capacity retention rate decreases, particularly at 50 ° C. The cycle capacity maintenance rate has decreased.
[0121]
  On the other hand, Example4In Examples 25 to 28, the average particle diameter of the first lithium transition metal composite oxide is in the range of 2 μm to 30 μm, and the average particle diameter of the second lithium transition metal composite oxide is constant at 15 μm. By using the mixed mixture as the positive electrode active material, the contact area between the positive electrode active material and the electrolytic solution is reduced, and the first lithium transition metal composite oxide and the second lithium transition metal composite oxide are reduced. Thoroughly mixed. Therefore, the example4In Examples 25 to 28, as compared with Comparative Examples 5 to 8, the 100 cycle capacity retention rate at 50 ° C. is improved.
[0122]
  From the above, the positive electrode active material has an average particle size of 2 μm or more and 30 μm of the first lithium transition metal composite oxide and the second lithium transition metal composite oxide when the nonaqueous electrolyte secondary battery is manufactured. By setting it in the following range, the 100 cycle capacity maintenance rate at 50 ° C. is improved.
[0123]
  Next, the example4Table 4 shows the evaluation results of the initial capacities in Examples 33 to 36 and Comparative Examples 9 to 12, the 100 cycle capacity retention at 23 ° C., and the 100 cycle capacity retention at 50 ° C. The mixing ratio of the first lithium transition metal composite oxide and the second lithium transition metal composite oxide is as follows: first lithium transition metal composite oxide to second lithium transition metal composite oxide = 50 wt% 50% by weight.
[0124]
[Table 4]

[0125]
  From the evaluation results in Table 4, the first lithium transition metal composite oxide (Li _x Ni _1-yz Co _y M _Z O ₂ ) And the second lithium transition metal composite oxide (Li _s Ni _1-tu Mn _t M ' _u O ₂ In Example 1 and Examples 33 to 36 in which the range of the ratio t of Mn is 0.05 or more and 0.50 or less, the range of the ratio y or t is 0.05 or less, and one of them is 0. Compared with Comparative Examples 9 to 11 in the range of 0.05 or more and 0.50 or less, it can be seen that the 50 ° C. and 100 cycle capacity retention rate is improved.
[0126]
  In Comparative Example 9, the Co ratio y of 1 lithium transition metal composite oxide was 0.01, and Comparative Example 12 was the case where the Mn ratio t of the second lithium transition metal composite oxide was 0.01 It is. As described above, in Comparative Examples 9 to 11, the Co ratio y in the first lithium transition metal composite oxide is 0.01, or the Mn ratio t in the second lithium transition metal composite oxide is 0. By setting the ratio to 0.01, each crystal structure becomes unstable, and the charge / discharge cycle capacity retention rate is lowered due to deterioration of the crystal structure of the positive electrode active material each time charge / discharge is repeated. In particular, in the positive electrode active material, the deterioration of the crystal structure is promoted in a high temperature environment, and the 100 cycle capacity maintenance rate at 50 ° C. is remarkably reduced.
[0127]
  On the other hand, Example4In Examples 33 to 36, the ratio y of Co in the first lithium transition metal composite oxide and the second lithium transition metal composite oxide (Li _s Ni _1-tu Mn _t M ' _u O ₂ ) When the range of the Mn ratio t is 0.05 or more and 0.50 or less, each crystal structure in the first lithium transition metal composite oxide and the second lithium transition metal composite oxide is stable. Thus, an excellent charge / discharge cycle capacity retention rate can be obtained even in a high temperature environment.
[0128]
  Moreover, from the evaluation results shown in Table 4, the examples4Examples 33 to 36 are the first lithium transition metal composite oxide (Li _x Ni _1-yz Co _y M _Z O ₂ ) In Co or the second lithium transition metal composite oxide (Li _s Ni _1-tu Mn _t M ' _u O ₂ The initial capacity is increased as compared with Comparative Examples 10 to 12 in which the range of the ratio t of Mn exceeds 0.50 and one is 0.05 or more and less than 0.50. I understand that.
[0129]
  Comparative Example 10 is a first lithium transition metal composite oxide in which the Co ratio y is 0.60, and Comparative Example 12 is a second lithium transition metal composite oxide in which the Mn ratio t is 0.60. This is the case. As in Comparative Examples 10 to 12, by setting the ratio of Co and Mn to be larger than 0.5, the capacity of the positive electrode active material as a whole was reduced, so that the initial capacity was reduced.
[0130]
  On the other hand, Example4In Examples 33 to 36, the range of the ratio y of Co in the first lithium transition metal composite oxide and the ratio t of Mn in the second lithium transition metal composite oxide is 0.05 or more, 0 By setting it to .50 or less, the crystal structure was stabilized and the initial capacity was increased.
[0131]
  As described above, when producing a nonaqueous electrolyte secondary battery, the ratio of Co in the first lithium transition metal composite oxide and Mn in the second lithium transition metal composite oxide is 0.05 or more. Thus, it was found that by setting the range to 0.50 or less, it is possible to increase the initial capacity and improve the charge / discharge cycle characteristics.
[0132]
【The invention's effect】
  As described above in detail, according to the present invention, by using a positive electrode active material containing a mixture of a first positive electrode material having a high capacity and a second positive electrode material having a stable crystal structure. In addition, the capacity of the initial capacity is increased and the energy density is improved, and a nonaqueous electrolyte secondary battery having a good charge / discharge cycle capacity maintenance rate can be obtained not only at room temperature but also in a high temperature environment.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a nonaqueous electrolyte secondary battery according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Nonaqueous electrolyte secondary battery, 2 Positive electrode, 3 Negative electrode, 4 Separator, 5 Battery can, 6 Insulation board, 7 Positive electrode lead, 8 Thin plate for current interruption, 9 Battery cover, 10 Negative electrode lead, 11 Insulation sealing gasket, 12 Center Pin, 13 Safety valve, 14 PTC element

Claims (6)

A first positive electrode material comprising a first lithium transition metal composite oxide having a layered structure represented by Formula 1 ;
A positive electrode active material comprising a mixture with a second positive electrode material made of a second lithium transition metal composite oxide having a layered structure represented by Formula 2 .

The mixing ratio of each of the first positive electrode material and the second positive electrode material is in the range of 15 wt% or more and 85 wt% or less with respect to the entire positive electrode active material. Positive electrode active material. The average particle diameter of each of the first positive electrode material and the second positive electrode material is 2 μm. m 30μ m The positive electrode active material according to claim 1, wherein the positive electrode active material is in the following range. A positive electrode in which a positive electrode mixture layer containing a positive electrode active material is formed on a positive electrode current collector;
A negative electrode in which a negative electrode mixture layer containing a negative electrode active material is formed on a negative electrode current collector;
With a non-aqueous electrolyte,
The positive electrode active material includes a first positive electrode material composed of a first lithium transition metal composite oxide having a layered structure represented by Formula 1 and a second lithium transition metal composite oxide having a layered structure represented by Formula 2. A non-aqueous electrolyte secondary battery comprising a mixture with a second positive electrode material.

The mixing ratio of each of the first positive electrode material and the second positive electrode material is in the range of 15 wt% or more and 85 wt% or less with respect to the entire positive electrode active material. Non-aqueous electrolyte secondary battery. The average particle diameter of each of the first positive electrode material and the second positive electrode material is 2 μm. m 30μ m The nonaqueous electrolyte secondary battery according to claim 4, wherein the range is as follows.

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