JP4952074B2 - Non-aqueous electrolyte and non-aqueous electrolyte secondary battery - Google Patents

Description

  The present invention relates to a non-aqueous electrolyte and a non-aqueous electrolyte secondary battery using the same.

With the recent reduction in weight and size of electrical products, development of lithium secondary batteries having high energy density is in progress. Further, as the application field of lithium secondary batteries expands, further improvement in battery characteristics is desired.
Under such circumstances, secondary batteries using metal lithium as a negative electrode are actively studied as batteries capable of achieving high capacity. However, metal lithium may grow into a dendritic shape due to repeated charge and discharge, and this may reach the positive electrode, causing a short circuit inside the battery. This is a practical application of lithium secondary batteries using metal lithium as the negative electrode. It is the biggest obstacle to making it.

  Further, a non-aqueous electrolyte secondary battery using a carbonaceous material capable of inserting and extracting lithium such as coke, artificial graphite or natural graphite in the negative electrode instead of metallic lithium has been proposed. In such a non-aqueous electrolyte secondary battery, since lithium does not grow in a dendrite shape, the battery life and safety can be improved. In particular, non-aqueous electrolyte secondary batteries using graphite-based carbonaceous materials such as artificial graphite and natural graphite are attracting attention as being able to meet the demand for higher capacity.

Further, in recent years, in order to obtain a higher capacity, for example, negative electrode active materials made of alloys such as silicon (Si), tin (Sn), and lead (Pb) have been proposed (see, for example, Patent Documents 1 and 2). ).
In addition, in order to improve the load characteristics, cycle characteristics, storage characteristics, low temperature characteristics, etc. of non-aqueous electrolyte secondary batteries, electrolytes containing various compounds in addition to the electrolyte and the main solvent have been proposed. ing.

For example, an electrolytic solution containing a certain amount of vinylene carbonate and its derivative (for example, see Patent Document 3) or side chain in order to suppress decomposition of the electrolytic solution of the non-aqueous electrolyte secondary battery using a graphite-based negative electrode An electrolytic solution containing a carbonate derivative having an unsaturated bond, such as an electrolytic solution containing a certain amount of an ethylene carbonate derivative having a non-conjugated unsaturated bond (see, for example, Patent Document 4) has been proposed.
In the electrolytic solution containing these compounds, the compound is reduced and decomposed on the negative electrode surface to form a film, and the excessive decomposition of the electrolytic solution is suppressed by this film. In addition, an electrolytic solution using a halogen-containing carbonate has also been proposed (see, for example, Patent Document 5).

Japanese Patent Laid-Open No. 11-176470 JP 2004-87284 A JP-A-8-45545 JP 2000-40526 A JP 11-195429 A

However, a technique for further improving the cycle characteristics has been demanded for the non-aqueous electrolyte solution.
The present invention was devised in view of the above problems, and an object thereof is to provide a non-aqueous electrolyte solution and a non-aqueous electrolyte secondary battery using the non-aqueous electrolyte solution that can obtain more excellent cycle characteristics. And

  The inventors of the present invention have intensively studied to solve the above problems, and as a result, the chain carbonate represented by the formula (1) described later is contained in the non-aqueous electrolyte and used for the non-aqueous electrolyte secondary battery. As a result, it has been found that an effect superior to that of the conventional improved method can be obtained, and the present invention has been completed.

（上記式（１）において、Ｘはそれぞれ独立に水素又は任意の基を表わす。また、Ｒは置換基を有してもよいアルキル基を表わす。さらに、ｎは０以上の整数を表わす。） That is, the gist of the present invention resides in a non-aqueous electrolytic solution characterized by containing a chain carbonate represented by the following formula (1) in a non-aqueous solvent (claim 1).

(In the above formula (1), X independently represents hydrogen or an arbitrary group. R represents an alkyl group which may have a substituent. Further, n represents an integer of 0 or more.)

とは異なる基であることが好ましい（請求項２）。 At this time, in the above formula (1), R is

It is preferably a group different from (Claim 2).

  The chain carbonate is preferably bis (2,2-difluoroethyl) carbonate.

Further, in the above formula (1), n is preferably an integer of 0 or more and 7 or less (claim 4).
Further, the electrolytic solution further contains a carbonate having at least one of an unsaturated bond and a halogen atom, excluding the chain carbonate represented by the formula (1) (hereinafter referred to as “predetermined carbonate” as appropriate). It is preferable to do. (Claim 5)
At this time, it is preferable that the concentration of the predetermined carbonate in the non-aqueous electrolyte is 0.01 wt% or more and 70 wt% or less (Claim 6).
The predetermined carbonate is preferably at least one carbonate selected from the group consisting of vinylene carbonate, vinyl ethylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate, and derivatives thereof (Claim 7).

  Another gist of the present invention resides in a non-aqueous electrolyte secondary battery comprising a negative electrode and a positive electrode capable of inserting and extracting lithium ions, and the non-aqueous electrolyte solution (Claim 8). .

According to the non-aqueous electrolyte solution of the present invention, when used in a non-aqueous electrolyte secondary battery, it is possible to obtain cycle characteristics superior to those of the prior art.
Moreover, according to the non-aqueous electrolyte secondary battery of the present invention, it is possible to obtain cycle characteristics superior to those of the prior art.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail. However, the description of the constituent elements described below is an example (representative example) of an embodiment of the present invention, and the present invention is arbitrarily selected without departing from the gist thereof. It can be implemented with deformation.

（上記式（１）において、Ｘはそれぞれ独立に水素又は任意の基を表わす。また、Ｒは置換基を有してもよいアルキル基を表わす。さらに、ｎは０以上の整数を表わす。） [I. Non-aqueous electrolyte]
The nonaqueous electrolytic solution of the present invention contains at least one chain carbonate represented by the following formula (1) (hereinafter, referred to as “specific chain carbonate” as appropriate). The specific chain carbonate can be used as a non-aqueous solvent in the non-aqueous electrolyte of the present invention, but the non-aqueous electrolyte of the present invention may appropriately contain a non-aqueous solvent. Moreover, the non-aqueous electrolyte solution of the present invention usually contains an electrolyte, and further contains a predetermined carbonate and an additive as appropriate.

(In the above formula (1), X independently represents hydrogen or an arbitrary group. R represents an alkyl group which may have a substituent. Further, n represents an integer of 0 or more.)

[I-1. Specific chain carbonate]
The specific chain carbonate according to the present invention is a chain carbonate represented by the above formula (1).
In the above formula (1), X represents hydrogen or an arbitrary group. Here, X which exists in Formula (1) may mutually be same kind, and may differ.

Moreover, the group which can be used as X can use arbitrary groups, unless the effect of this invention is impaired remarkably. Specific examples include halogens such as fluorine (fluoro group), chlorine (chloro group), bromine (bromo group), iodine (iodo group); methyl group, ethyl group, n-propyl group, i-propyl group, etc. A cycloalkyl group such as a cyclohexyl group; an aryl group such as a phenyl group or a naphthyl group; Arbitrary hydrogen in the alkyl group, cycloalkyl group and aryl group may be substituted with halogen.
Among these, X is preferably hydrogen or fluorine in view of the stability of the specific chain carbonate as an organic substance and the stability of the protective coating layer produced when used in a non-aqueous electrolyte secondary battery.

  Further, in the above formula (1), n represents an arbitrary integer of 0 or more. However, if the molecular weight of the specific chain carbonate represented by the formula (1) becomes too large, the effect on the added amount may be reduced. Therefore, n is usually 7 or less, preferably 4 or less, more preferably 3 or less. It is desirable that

In the above formula (1), R represents an alkyl group which may have a substituent.
Furthermore, the carbon number of R is arbitrary as long as the effects of the present invention are not significantly impaired. However, if the molecular weight of the specific chain carbonate represented by the formula (1) becomes too large, the effect on the added amount may be reduced. Therefore, the carbon number of R is usually 10 or less, preferably 5 or less, more preferably. Is preferably 3 or less.

  In addition, R is an alkyl group having no branched chain because of the stability of the specific chain carbonate as an organic substance and the stability of the protective coating layer generated when used in a non-aqueous electrolyte secondary battery. An alkyl group which is unsubstituted or substituted only with fluorine is preferable.

  Specific examples of R include methyl group, fluoromethyl group, ethyl group, 2-fluoroethyl group, 2,2-difluoroethyl group, 2,2,2-trifluoroethyl group, n-propyl group, 3- Fluoro-n-propyl group, 3,3-difluoro-n-propyl group, 3,3,3-trifluoro-n-propyl group, i-propyl group, 1,1,1,3,3,3-hexa Examples include a fluoro-i-propyl group.

  Among these, since it is considered that it can be easily produced, a methyl group, an ethyl group, a 2-fluoroethyl group, a 2,2-difluoroethyl group, a 2,2,2-trifluoroethyl group, An n-propyl group, a 3-fluoro-n-propyl group, and a 3,3-difluoro-n-propyl group are preferable, and a methyl group, an ethyl group, and an n-propyl group are more preferable.

（ただし、この式において、ｎは上記式（１）と同じ数である）とは異なる構造を有する基であることが好ましい。非対称とすることにより、溶媒の融点を低下させる効果がある他、非対称カーボネート類は保存特性、サイクル特性を向上させる効果が得られる（特開平２−１４８６６５号公報、特開平４−１０４４６８号公報）。 Moreover, when the specific chain carbonate is represented by the formula (1), the configuration of the formula (1) is preferably left-right asymmetric. That is, in the above formula (1), R is

(However, in this formula, n is preferably the same number as in the above formula (1)) and is preferably a group having a different structure. In addition to the effect of lowering the melting point of the solvent, the asymmetric carbonates have the effect of improving the storage characteristics and cycle characteristics (see JP-A-2-148665 and JP-A-4-104468). .

However, among those in which the structure of the formula (1) is symmetrical, bis (2,2-difluoroethyl) carbonate can be suitably used. That is, in Formula (1), it is also preferable that X is hydrogen, n is 0, and R is a 2,2-difluoroethyl group.
However, it is usually more preferable to use a specific chain carbonate having a structure in which the structure of the formula (1) is asymmetrical.

  Specific examples of the specific chain carbonate represented by the formula (1) include 2,2-difluoroethyl methyl carbonate, 2,2-difluoroethyl ethyl carbonate, 2,2-difluoroethyl-2′-fluoroethyl carbonate, Bis (2,2-difluoroethyl) carbonate, 2,2-difluoroethyl-2 ′, 2 ′, 2′-trifluoroethyl carbonate, 2,2-difluoroethyl-n-propyl carbonate, 2,2-difluoroethyl -3′-fluoro-n-propyl carbonate, 2,2-difluoro-3 ′, 3 ′, 3′-trifluoro-n-propyl carbonate, 3,3-difluoro-n-propylmethyl carbonate, 3,3- Difluoro-n-propyl ethyl carbonate, 3,3-difluoro-n-propyl 2 -Fluoroethyl carbonate, 3,3-difluoro-n-propyl-2 ', 2'-difluoroethyl carbonate, 3,3-difluoro-n-propyl-2', 2 ', 2'-trifluoroethyl carbonate, 3 , 3-difluoro-n-propyl-n-propyl carbonate, 3,3-difluoro-n-propyl-3′-fluoro-n-propyl carbonate, bis (3,3-difluoro-n-propyl) carbonate, 3, 3-difluoro-n-propyl-3 ′, 3 ′, 3′-trifluoro-n-propyl carbonate, methyl-2,2,3,3-tetrafluoro-n-propyl carbonate, ethyl-2,2,3 , 3-tetrafluoro-n-propyl carbonate, 2-fluoro-2 ′, 2 ′, 3 ′, 3′-tetrafluoro-n-propyl Pyrcarbonate, 2,2-difluoroethyl-2 ′, 2 ′, 3 ′, 3′-tetrafluoro-n-propyl carbonate, 2,2,3,3-tetrafluoro-n-propyl-2 ′, 2 ′ , 2′-trifluoroethyl carbonate, n-propyl-2,2,3,3-tetrafluoro-n-propyl carbonate, 3-fluoro-n-propyl-2 ′, 2 ′, 3 ′, 3′-tetra Fluoro-n-propyl carbonate, 3,3-difluoro-n-propyl-2 ′, 2 ′, 3 ′, 3′-tetrafluoro-n-propyl carbonate, bis (2,2,3,3-tetrafluoro- n-propyl) carbonate, and the like.

Especially, as above-mentioned, the specific chain carbonate from which the structure of Formula (1) becomes left-right asymmetric, and bis (2, 2- difluoroethyl) carbonate are preferable.
Further, among these, 2,2-difluoroethyl methyl carbonate, 2,2-difluoroethyl ethyl carbonate, bis (2,2-difluoroethyl) carbonate, 2,2-difluoroethyl-n- Propyl carbonate is preferred.

Among them, 2,2-difluoroethyl methyl carbonate, 2,2-difluoroethyl ethyl carbonate, and 2,2-difluoroethyl-n-propyl carbonate are more preferable.
In addition, when making the non-aqueous electrolyte solution of this invention contain a specific chain carbonate, a specific chain carbonate may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios. .

  Further, when the non-aqueous electrolyte of the present invention contains a specific chain carbonate, the blending amount thereof is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.01% by weight or more, preferably 0.8. It is desirable to be 1% by weight or more. Below this lower limit, when the non-aqueous electrolyte of the present invention is used in a non-aqueous electrolyte secondary battery, the non-aqueous electrolyte secondary battery may not exhibit a sufficient cycle characteristic improving effect.

  Further, among them, when using a specific chain carbonate as a non-aqueous solvent in the non-aqueous electrolyte of the present invention, it is usually 95% by volume or less with respect to all the non-aqueous solvents in the non-aqueous electrolyte excluding the electrolyte, Preferably it is 70 volume% or less. If this upper limit is exceeded, dissolution of the electrolyte becomes insufficient, and as a result of reducing electrolyte properties such as electrical conductivity, battery characteristics may be reduced.

When the above-mentioned specific chain carbonate is contained in the non-aqueous electrolyte, the charge / discharge cycle characteristics of a non-aqueous electrolyte secondary battery using the non-aqueous electrolyte can be improved.
The reason why the charge / discharge cycle characteristics are improved is not clear in detail, but is estimated as follows. That is, when the specific chain carbonate is contained in the non-aqueous electrolyte, the specific chain carbonate reacts in the non-aqueous electrolyte secondary battery using the non-aqueous electrolyte, and the surface of the negative electrode active material is good. It is presumed that a protective coating layer is formed, thereby suppressing side reactions and suppressing cycle deterioration. At this time, the presence of a hydrogen atom and a fluorine atom at one or more terminal carbons in the specific chain carbonate represented by the above formula (1) improves the characteristics of the protective coating layer in some form. It is guessed that it contributes to doing.

  In addition, there is no restriction | limiting in the manufacturing method of a specific chain carbonate, A well-known method can be used arbitrarily.

[I-2. Predetermined carbonate]
The non-aqueous electrolyte solution of the present invention preferably contains a predetermined carbonate in addition to the specific chain carbonate. The predetermined carbonate according to the present invention is a carbonate having at least one of an unsaturated bond and a halogen atom. That is, if the predetermined carbonate according to the present invention is a carbonate, it may have only an unsaturated bond, may have only a halogen atom, and has both an unsaturated bond and a halogen atom. May be.
However, the specific chain carbonate is excluded from the predetermined carbonate. That is, the compound corresponding to the definition of the specific chain carbonate described above is not handled as the predetermined carbonate.

  Among the predetermined carbonates, as the predetermined carbonate having an unsaturated bond (this is appropriately abbreviated as “predetermined unsaturated carbonate”), a carbon-carbon unsaturated bond such as a carbon-carbon double bond or a carbon-carbon triple bond is used. Other than the specific chain carbonate, any carbonate other than the specific chain carbonate can be used. In addition, the carbonate which has an aromatic ring shall also be contained in the predetermined unsaturated carbonate which has an unsaturated bond.

  Examples of the predetermined unsaturated carbonate include vinylene carbonate derivatives, ethylene carbonate derivatives substituted with a substituent having an aromatic ring or a carbon-carbon unsaturated bond, phenyl carbonates, vinyl carbonates, allyl carbonates, and the like. It is done.

  Specific examples of vinylene carbonate derivatives include vinylene carbonate, methyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, phenyl vinylene carbonate, 4,5-diphenyl vinylene carbonate, and the like.

  Specific examples of the ethylene carbonate derivatives substituted with a substituent having an aromatic ring or a carbon-carbon unsaturated bond include vinyl ethylene carbonate, 4,5-divinyl ethylene carbonate, phenyl ethylene carbonate, 4,5-diphenyl. And ethylene carbonate.

  Furthermore, specific examples of phenyl carbonates include diphenyl carbonate, ethyl phenyl carbonate, methyl phenyl carbonate, t-butyl phenyl carbonate, and the like.

Specific examples of vinyl carbonates include divinyl carbonate and methyl vinyl carbonate.
Furthermore, specific examples of allyl carbonates include diallyl carbonate, allyl methyl carbonate, and the like.

  Among these predetermined unsaturated carbonates, as the predetermined carbonate, vinylene carbonate derivatives, ethylene carbonate derivatives substituted with a substituent having an aromatic ring or a carbon-carbon unsaturated bond are preferable, and in particular, vinylene carbonate, 4, Since 5-diphenyl vinylene carbonate, 4,5-dimethyl vinylene carbonate, and vinyl ethylene carbonate form a stable interface protective film, they are more preferably used.

  On the other hand, among the predetermined carbonates, the predetermined carbonate having a halogen atom (this is appropriately abbreviated as “predetermined halogenated carbonate”) is not particularly limited as long as it has a halogen atom, and has a specific chain shape. Any halogenated carbonate other than carbonate can be used.

Specific examples of the halogen atom that the predetermined halogenated carbonate has include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Among these, a fluorine atom or a chlorine atom is preferable, and a fluorine atom is particularly preferable.
The number of halogen atoms contained in the predetermined halogenated carbonate is not particularly limited as long as it is 1 or more, but is usually 6 or less, preferably 4 or less. When the predetermined halogenated carbonate has a plurality of halogen atoms, they may be the same as or different from each other.

  Examples of the predetermined halogenated carbonate include ethylene carbonate derivatives, dimethyl carbonate derivatives, ethyl methyl carbonate derivatives, diethyl carbonate derivatives and the like.

  Specific examples of the ethylene carbonate derivatives include fluoroethylene carbonate, chloroethylene carbonate, 4,4-difluoroethylene carbonate, 4,5-difluoroethylene carbonate, 4,4-dichloroethylene carbonate, 4,5-dichloroethylene carbonate, 4- Fluoro-4-methylethylene carbonate, 4-chloro-4-methylethylene carbonate, 4,5-difluoro-4-methylethylene carbonate, 4,5-dichloro-4-methylethylene carbonate, 4-fluoro-5-methylethylene Carbonate, 4-chloro-5-methylethylene carbonate, 4,4-difluoro-5-methylethylene carbonate, 4,4-dichloro-5-methylethylene carbonate, 4- (fluoromethyl) Ethylene carbonate, 4- (chloromethyl) -ethylene carbonate, 4- (difluoromethyl) -ethylene carbonate, 4- (dichloromethyl) -ethylene carbonate, 4- (trifluoromethyl) -ethylene carbonate, 4- (trichloromethyl) -Ethylene carbonate, 4- (fluoromethyl) -4-fluoroethylene carbonate, 4- (chloromethyl) -4-chloroethylene carbonate, 4- (fluoromethyl) -5-fluoroethylene carbonate, 4- (chloromethyl)- 5-chloroethylene carbonate, 4-fluoro-4,5-dimethylethylene carbonate, 4-chloro-4,5-dimethylethylene carbonate, 4,5-difluoro-4,5-dimethylethylene carbonate, 4,5-dichloro- 4, - dimethyl carbonate, 4,4-difluoro-5,5-dimethylethylene carbonate, 4,4-dichloro-5,5-dimethylethylene carbonate, and the like.

  Specific examples of dimethyl carbonate derivatives include fluoromethyl methyl carbonate, difluoromethyl methyl carbonate, trifluoromethyl methyl carbonate, bis (fluoromethyl) carbonate, bis (difluoro) methyl carbonate, bis (trifluoro) methyl carbonate, Examples include chloromethyl methyl carbonate, dichloromethyl methyl carbonate, trichloromethyl methyl carbonate, bis (chloromethyl) carbonate, bis (dichloro) methyl carbonate, bis (trichloro) methyl carbonate, and the like.

  Furthermore, specific examples of the ethyl methyl carbonate derivatives include 2-fluoroethyl methyl carbonate, ethyl fluoromethyl carbonate, 2-fluoroethyl fluoromethyl carbonate, ethyl difluoromethyl carbonate, 2,2,2-trifluoroethyl methyl carbonate, 2-fluoroethyl difluoromethyl carbonate, ethyl trifluoromethyl carbonate, 2-chloroethyl methyl carbonate, ethyl chloromethyl carbonate, 2,2-dichloroethyl methyl carbonate, 2-chloroethyl chloromethyl carbonate, ethyl dichloromethyl carbonate, 2, 2,2-trichloroethyl methyl carbonate, 2,2-dichloroethyl chloromethyl carbonate, 2-chloroethyl dichloromethyl carbonate Over DOO, ethyl trichloromethyl carbonate, and the like.

  Specific examples of diethyl carbonate derivatives include ethyl- (2-fluoroethyl) carbonate, bis (2-fluoroethyl) carbonate, ethyl- (2,2,2-trifluoroethyl) carbonate, 2,2, 2-trifluoroethyl-2′-fluoroethyl carbonate, bis (2,2,2-trifluoroethyl) carbonate, ethyl- (2-chloroethyl) carbonate, ethyl- (2,2-dichloroethyl) carbonate, bis ( 2-chloroethyl) carbonate, ethyl- (2,2,2-trichloroethyl) carbonate, 2,2-dichloroethyl-2'-chloroethyl carbonate, bis (2,2-dichloroethyl) carbonate, 2,2,2 -Trichloroethyl-2'-chloroethyl carbonate, 2,2,2- Rikuroroechiru -2 ', 2'-dichloroethyl carbonate, bis (2,2,2-trichloroethyl) carbonate, and the like.

  Among these predetermined halogenated carbonates, carbonates having fluorine atoms are preferable, ethylene carbonate derivatives having fluorine atoms are more preferable, and in particular, fluoroethylene carbonate, 4- (fluoromethyl) -ethylene carbonate, 4,4-difluoroethylene. Since carbonate and 4,5-difluoroethylene carbonate form an interface protective film, they are more preferably used.

  Furthermore, as the predetermined carbonate, a carbonate having both an unsaturated bond and a halogen atom (this is appropriately abbreviated as “predetermined halogenated unsaturated carbonate”) can also be used. There is no restriction | limiting in particular as a predetermined | prescribed halogenated unsaturated carbonate, As long as the effect of this invention is not impaired remarkably, arbitrary halogenated unsaturated carbonates can be used.

  Examples of the predetermined halogenated unsaturated carbonate include vinylene carbonate derivatives, ethylene carbonate derivatives substituted with a substituent having an aromatic ring or a carbon-carbon unsaturated bond, phenyl carbonates, vinyl carbonates, allyl carbonates, etc. Is mentioned.

  Specific examples of the vinylene carbonate derivatives include fluorovinylene carbonate, 4-fluoro-5-methylvinylene carbonate, 4-fluoro-5-phenylvinylene carbonate, chlorovinylene carbonate, 4-chloro-5-methylvinylene carbonate, 4- And chloro-5-phenyl vinylene carbonate.

  Specific examples of ethylene carbonate derivatives substituted with a substituent having an aromatic ring or a carbon-carbon unsaturated bond include 4-fluoro-4-vinylethylene carbonate, 4-fluoro-5-vinylethylene carbonate, 4 , 4-Difluoro-4-vinylethylene carbonate, 4,5-difluoro-4-vinylethylene carbonate, 4-chloro-5-vinylethylene carbonate, 4,4-dichloro-4-vinylethylene carbonate, 4,5-dichloro -4-vinylethylene carbonate, 4-fluoro-4,5-divinylethylene carbonate, 4,5-difluoro-4,5-divinylethylene carbonate, 4-chloro-4,5-divinylethylene carbonate, 4,5-dichloro -4,5-divinylethylene carbonate, 4 Fluoro-4-phenylethylene carbonate, 4-fluoro-5-phenylethylene carbonate, 4,4-difluoro-5-phenylethylene carbonate, 4,5-difluoro-4-phenylethylene carbonate, 4-chloro-4-phenylethylene Carbonate, 4-chloro-5-phenylethylene carbonate, 4,4-dichloro-5-phenylethylene carbonate, 4,5-dichloro-4-phenylethylene carbonate, 4,5-difluoro-4,5-diphenylethylene carbonate, 4,5-dichloro-4,5-diphenylethylene carbonate and the like.

  Further, specific examples of phenyl carbonates include fluoromethyl phenyl carbonate, 2-fluoroethyl phenyl carbonate, 2,2-difluoroethyl phenyl carbonate, 2,2,2-trifluoroethyl phenyl carbonate, chloromethyl phenyl carbonate, 2 -Chloroethyl phenyl carbonate, 2,2-dichloroethyl phenyl carbonate, 2,2,2-trichloroethyl phenyl carbonate, and the like.

  Specific examples of vinyl carbonates include fluoromethyl vinyl carbonate, 2-fluoroethyl vinyl carbonate, 2,2-difluoroethyl vinyl carbonate, 2,2,2-trifluoroethyl vinyl carbonate, chloromethyl vinyl carbonate, 2 -Chloroethyl vinyl carbonate, 2,2-dichloroethyl vinyl carbonate, 2,2,2-trichloroethyl vinyl carbonate, and the like.

  Furthermore, specific examples of allyl carbonates include fluoromethyl allyl carbonate, 2-fluoroethyl allyl carbonate, 2,2-difluoroethyl allyl carbonate, 2,2,2-trifluoroethyl allyl carbonate, chloromethyl allyl carbonate, 2 -Chloroethyl allyl carbonate, 2,2-dichloroethyl allyl carbonate, 2,2,2-trichloroethyl allyl carbonate, and the like.

  Among the examples of the predetermined halogenated unsaturated carbonate described above, the predetermined carbonate is selected from the group consisting of vinylene carbonate, vinyl ethylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate, and derivatives thereof, which are highly effective when used alone. It is particularly preferable to use one or more selected ones. Of the difluoroethylene carbonates, 4,5-difluoroethylene carbonate is particularly preferable.

  In addition, there is no restriction | limiting in particular in the molecular weight of predetermined carbonate, Although it is arbitrary unless the effect of this invention is impaired remarkably, Usually, 50 or more, Preferably it is 80 or more, Usually, 250 or less, Preferably it is 150 or less. If the molecular weight is too large, the solubility of the predetermined carbonate in the non-aqueous electrolyte solution is lowered, and the effects of the present invention may not be sufficiently exhibited.

  Moreover, there is no restriction | limiting in particular also in the manufacturing method of a predetermined carbonate, It is possible to select and manufacture a well-known method arbitrarily.

  Also about the predetermined carbonate demonstrated above, in the non-aqueous electrolyte solution of this invention, any 1 type may be contained independently and 2 or more types may be used together by arbitrary combinations and ratios.

  Further, there is no limitation on the blending amount of the predetermined carbonate with respect to the non-aqueous electrolyte of the present invention, and it is optional as long as the effects of the present invention are not significantly impaired. % Or more, preferably 0.1% by weight or more, more preferably 0.3% by weight or more, and usually 70% by weight or less, preferably 50% by weight or less, more preferably 40% by weight or less. Is desirable. Below the lower limit of this range, when the non-aqueous electrolyte solution of the present invention is used in a non-aqueous electrolyte secondary battery, the non-aqueous electrolyte secondary battery may hardly exhibit a sufficient cycle characteristic improving effect. In addition, if the ratio of the predetermined carbonate is too large, when the non-aqueous electrolyte of the present invention is used in a non-aqueous electrolyte secondary battery, the high-temperature storage characteristics and trickle of the non-aqueous electrolyte secondary battery There is a tendency for the charging characteristics to decrease, and in particular, the amount of gas generation increases, and the discharge capacity maintenance rate may decrease.

  Furthermore, in the non-aqueous electrolyte of the present invention, the ratio of the specific chain carbonate and the predetermined carbonate is also arbitrary, but the relative weight ratio of both expressed by “weight of the specific chain carbonate / weight of the predetermined carbonate” It is usually 0.0001 or more, preferably 0.001 or more, more preferably 0.01 or more, and usually 1000 or less, preferably 100 or less, more preferably 10 or less. If the relative weight ratio is too low or too high, it may be difficult to obtain a synergistic effect.

  When the non-aqueous electrolyte contains the specific chain carbonate and the predetermined carbonate, the charge / discharge cycle characteristics of a non-aqueous electrolyte secondary battery using the non-aqueous electrolyte can be improved. Although the details of this reason are not clear, it is estimated as follows. That is, the specific chain carbonate contained in the non-aqueous electrolyte and the predetermined carbonate react together to form a good protective film layer on the surface of the negative electrode active material, thereby suppressing side reactions and cycle deterioration. Is presumed to be suppressed. Although details are unknown, it is speculated that the presence of the specific chain carbonate and the predetermined carbonate in the electrolyte simultaneously contributes to improving the properties of the protective film in some form.

[I-3. Nonaqueous solvent]
Any nonaqueous solvent that can be contained in the nonaqueous electrolytic solution of the present invention can be used as long as the effects of the present invention are not significantly impaired. In addition, it is also possible to use the specific linear carbonate mentioned above as a nonaqueous solvent, and it is also possible to use a predetermined carbonate as a nonaqueous solvent. Moreover, a non-aqueous solvent (including a specific chain carbonate and a predetermined carbonate) may be used alone, or two or more kinds may be used in any combination and ratio.

  Examples of commonly used non-aqueous solvents include cyclic carbonates, chain carbonates, chain and cyclic carboxylic acid esters, chain and cyclic ethers, phosphorus-containing organic solvents, and sulfur-containing organic solvents.

  Although there is no restriction | limiting in cyclic carbonate, As an example of what is normally used, ethylene carbonate, propylene carbonate, butylene carbonate, etc. are mentioned. Among these, ethylene carbonate and propylene carbonate are preferable in that the solute easily dissolves because of a high dielectric constant, and the cycle characteristics are good when a non-aqueous electrolyte secondary battery is obtained.

  The chain carbonate is not limited, but examples of commonly used ones include dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl-n-propyl carbonate, ethyl-n-propyl carbonate, di-n-propyl. And carbonate. Among them, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, methyl-n-propyl carbonate, and ethyl-n-propyl carbonate are preferable. Particularly when dimethyl carbonate, ethyl methyl carbonate, and diethyl carbonate are used as a non-aqueous electrolyte secondary battery. It is preferable in terms of good cycle characteristics.

  Furthermore, although there is no restriction | limiting also in chain | strand carboxylic acid ester, As an example of what is normally used, methyl acetate, ethyl acetate, acetic acid-n-propyl, acetic acid-i-propyl, acetic acid-n-butyl, acetic acid-i -Butyl, acetate-t-butyl, methyl propionate, ethyl propionate, propionate-n-propyl, propionate-i-propyl, propionate-n-butyl, propionate-i-butyl, propionate-t- Examples include butyl. Among these, ethyl acetate, methyl propionate, and ethyl propionate are more preferable. In addition, it is also possible to use the specific chain carbonate represented by the above formula (1) as the chain carbonate.

  Moreover, although there is no restriction | limiting also in cyclic carboxylic acid ester, As an example of what is used normally, (gamma) -butyrolactone, (gamma) -valerolactone, (delta) -valerolactone, etc. are mentioned. Among these, γ-butyrolactone is more preferable.

  Furthermore, although there is no restriction | limiting also in chain | strand ether, As an example of what is used normally, dimethoxymethane, dimethoxyethane, diethoxymethane, diethoxyethane, ethoxymethoxymethane, ethoxymethoxyethane, etc. are mentioned. Among these, dimethoxyethane and diethoxyethane are more preferable.

  Moreover, although there is no restriction | limiting also in cyclic ether, Tetrahydrofuran, 2-methyltetrahydrofuran, etc. are mentioned as an example of what is normally used.

  Furthermore, although there is no limitation on the phosphorus-containing organic solvent, examples of commonly used organic solvents include phosphate esters such as trimethyl phosphate, triethyl phosphate, and triphenyl phosphate; trimethyl phosphite, triethyl phosphite. Phosphites such as triphenyl phosphite; phosphine oxides such as trimethylphosphine oxide, triethylphosphine oxide, triphenylphosphine oxide, and the like.

  Moreover, although there is no restriction | limiting also in a sulfur-containing organic solvent, As an example of what is used normally, ethylene sulfite, 1, 4- propane sultone, 1, 4- butane sultone, methyl methanesulfonate, busulfan, sulfolane, sulfolene, Examples include dimethylsulfone, diphenylsulfone, methylphenylsulfone, dibutyldisulfide, dicyclohexyldisulfide, tetramethylthiuram monosulfide, N, N-dimethylmethanesulfonamide, N, N-diethylmethanesulfonamide, and the like.

  Among these, it is preferable to use ethylene carbonate and / or propylene carbonate, which are cyclic carbonates, and it is more preferable to use a mixture of these and chain carbonate.

  Further, when the cyclic carbonate and the chain carbonate are used in combination as a non-aqueous solvent as described above, the preferable content of the chain carbonate in the non-aqueous solvent in the non-aqueous electrolyte solution of the present invention is usually 30% by volume or more. , Preferably 50% by volume or more, and usually 95% by volume or less, preferably 90% by volume or less. On the other hand, the suitable content of the cyclic carbonate in the non-aqueous solvent in the non-aqueous electrolyte of the present invention is usually 5% by volume or more, preferably 10% by volume or more, and usually 50% by volume or less, preferably 40% by volume. % Or less. If the amount of chain carbonate is less than this range, the viscosity of the non-aqueous electrolyte solution of the present invention may increase. If it is too much, the dissociation degree of the lithium salt that is the electrolyte will decrease, and the non-aqueous electrolyte of the present invention will decrease. The electrical conductivity of the liquid may be reduced.

[I-4. Electrolytes]
There is no restriction | limiting in the electrolyte used for the non-aqueous electrolyte of this invention, A well-known thing can be arbitrarily employ | adopted if it is used as an electrolyte for the target non-aqueous electrolyte secondary battery. When the nonaqueous electrolytic solution of the present invention is used for a lithium secondary battery, a lithium salt is usually used as an electrolyte.

Specific examples of the electrolyte include inorganic lithium salts such as LiClO ₄ , LiAsF ₆ , LiPF ₆ , Li ₂ CO ₃ , LiBF ₄ ; LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , LiN (C ₂ F ₅ SO _{2) 2,} lithium cyclic 1,4-perfluoropropane disulfonyl _{imide, LiN (CF 3 SO 2)} (C 4 F 9 SO 2), LiC (CF 3 SO 2) 3, LiPF 4 (CF 3) 2, LiPF ₄ (C ₂ F ₅ ) ₂ , LiPF ₄ (CF ₃ SO ₂ ) ₂ , LiPF ₄ (C ₂ F ₅ SO ₂ ) ₂ , LiBF ₂ (CF ₃ ) ₂ , LiBF ₂ (C ₂ F ₅ ) ₂ , Fluorine-containing organic lithium salts such as LiBF ₂ (CF ₃ SO ₂ ) ₂ , LiBF ₂ (C ₂ F ₅ SO ₂ ) ₂ , lithium bis (oxalato) borate; KPF ₆ , NaPF ₆ , NaBF ₄ , Na ₂ CF ₃ SO Sodium salt such as ₃ or potassium Examples thereof include a lithium salt. Of these, LiPF ₆ , LiBF ₄ , LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , and LiN (C ₂ F ₅ SO ₂ ) ₂ are preferable, and LiPF ₆ and LiBF ₄ are particularly preferable.

Moreover, electrolyte may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio. In particular, when two types of specific inorganic lithium salts are used in combination, or when inorganic lithium salts and fluorine-containing organic lithium salts are used in combination, gas generation during continuous charging is suppressed, or deterioration after high-temperature storage is suppressed. Therefore, it is preferable. In particular, the combination and the LiPF ₆ and LiBF _4, and an inorganic lithium salt such as _{LiPF 6, LiBF 4, LiCF 3} SO 3, LiN (CF 3 SO 2) 2, LiN (C 2 F 5 SO 2) _2, etc. The combined use with a fluorine-containing organic lithium salt is preferred.

Further, when LiPF ₆ and LiBF ₄ are used in combination, it is preferable that LiBF ₄ is usually contained in a ratio of 0.01 wt% or more and 20 wt% or less with respect to the entire electrolyte. LiBF ₄ has a low degree of dissociation, and if the ratio is too high, the resistance of the electrolytic solution may be increased.
On the other hand, when inorganic lithium salts such as LiPF ₆ and LiBF ₄ are used in combination with fluorine-containing organic lithium salts such as LiCF ₃ SO ₃ , LiN (CF ₃ SO ₂ ) ₂ , and LiN (C ₂ F ₅ SO ₂ ) ₂ The ratio of the inorganic lithium salt in the entire electrolyte is preferably in the range of usually 70% by weight or more and 99% by weight or less. In general, the fluorine-containing organic lithium salt has a large molecular weight as compared with the inorganic lithium salt, and if the ratio is too high, the ratio of the solvent in the entire electrolytic solution may decrease, and the resistance of the electrolytic solution may be increased.

The concentration of the lithium salt in the non-aqueous electrolyte of the present invention is arbitrary as long as the effects of the present invention are not significantly impaired, but usually 0.5 mol · dm ⁻³ or more, preferably 0.6 mol · dm ^−3. or more, more preferably 0.8 mol · dm ^-3 or more, and usually 3 mol · dm ^-3 or less, preferably 2 mol · dm ^-3 or less, and more preferably 1.5 mol · dm ^-3 or less of. If this concentration is too low, the electrical conductivity of the non-aqueous electrolyte may become insufficient. If the concentration is too high, the electrical conductivity will decrease due to an increase in viscosity, and the non-aqueous electrolyte of the present invention was used. The performance of the non-aqueous electrolyte secondary battery may be reduced.

[I-5. Additive]
The nonaqueous electrolytic solution of the present invention preferably contains various additives as long as the effects of the present invention are not significantly impaired. As the additive, conventionally known additives can be arbitrarily used, and one kind may be used alone, or two or more kinds may be used in any combination and ratio. Examples of the additive include an overcharge inhibitor and an auxiliary agent for improving capacity maintenance characteristics and cycle characteristics after high temperature storage.

Examples of the overcharge inhibitor include aromatic compounds such as biphenyl, alkylbiphenyl, terphenyl, partially hydrogenated terphenyl, cyclohexylbenzene, t-butylbenzene, t-amylbenzene, diphenyl ether, and dibenzofuran; 2-fluoro Partially fluorinated products of the above aromatic compounds such as biphenyl, o-cyclohexylfluorobenzene, p-cyclohexylfluorobenzene; fluorinated anisole such as 2,4-difluoroanisole, 2,5-difluoroanisole, 2,6-difluoroaniol Compound etc. are mentioned.
In addition, an overcharge inhibiting agent may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  Further, when the non-aqueous electrolyte contains an overcharge inhibitor, the concentration thereof is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.1% by weight to 5% by weight with respect to the whole non-aqueous electrolyte. %. By including an overcharge inhibitor in the non-aqueous electrolyte, it is possible to suppress rupture and ignition of the non-aqueous electrolyte secondary battery due to overcharge, and the safety of the non-aqueous electrolyte secondary battery is improved. preferable.

  On the other hand, as an auxiliary agent for improving capacity maintenance characteristics and cycle characteristics after high temperature storage, for example, vinylene carbonate, vinyl ethylene carbonate, fluoroethylene carbonate, 4- (trifluoromethyl) -ethylene carbonate, phenylethylene carbonate, Carbonate compounds such as erythritan carbonate, spiro-bis-dimethylene carbonate; succinic anhydride, glutaric anhydride, maleic anhydride, citraconic anhydride, glutaconic anhydride, itaconic anhydride, diglycolic anhydride, cyclohexanedicarboxylic anhydride Carboxylic anhydrides such as cyclopentanetetracarboxylic dianhydride and phenylsuccinic anhydride; ethylene sulfite, 1,4-propane sultone, 1,4-butane sultone, methyl methanesulfonate, , Sulfolane, sulfolene, dimethylsulfone, diphenylsulfone, methylphenylsulfone, dibutyldisulfide, dicyclohexyldisulfide, tetramethylthiurammonosulfide, N, N-dimethylmethanesulfonamide, N, N-diethylmethanesulfonamide, etc. Sulfur-containing compounds; nitrogen-containing compounds such as 1-methyl-2-pyrrolidinone, 1-methyl-2-piperidone, 4-methyl-2-oxazolidinone, 1,4-dimethyl-2-imidazolidinone, N-methylsuccinimide Compound; Hydrocarbon compounds such as heptane, octane, cycloheptane; and fluorine-containing aromatic compounds such as fluorobenzene, difluorobenzene, and benzotrifluoride.

  In addition, an auxiliary agent may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  Further, when the non-aqueous electrolyte contains an auxiliary agent, its concentration is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.1% by weight to 5% by weight with respect to the whole non-aqueous electrolyte. is there.

[II. Non-aqueous electrolyte secondary battery]
The non-aqueous electrolyte secondary battery of the present invention includes a negative electrode and a positive electrode that can occlude and release lithium ions, and the non-aqueous electrolyte of the present invention.
As the non-aqueous electrolyte secondary battery of the present invention, the same configuration as that of a conventionally known non-aqueous electrolyte secondary battery can be arbitrarily adopted for the configuration other than the non-aqueous electrolyte. Usually, in a non-aqueous electrolyte secondary battery, a positive electrode and a negative electrode are laminated via a porous film (separator) impregnated with the non-aqueous electrolyte of the present invention, and these are stored in a case (exterior body). It has a form.

[II-1. Non-aqueous electrolyte]
As the non-aqueous electrolyte solution, the non-aqueous electrolyte solution of the present invention containing the above-mentioned specific chain carbonate or both the specific chain carbonate and the predetermined carbonate in a non-aqueous solvent is used.

[II-2. Negative electrode]
Any negative electrode can be used for the non-aqueous electrolyte secondary battery of the present invention as long as it can occlude and release lithium ions as long as the effects of the present invention are not impaired. Usually, a negative electrode in which a negative electrode active material is fixed is used as the negative electrode.

  Although there is no restriction | limiting in a negative electrode active material, For example, the carbonaceous material which can occlude and discharge | release lithium, a metal material, lithium metal, a lithium alloy etc. can be used. Moreover, a negative electrode active material may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  Among these, carbonaceous materials, alloys composed of one or more metals capable of inserting and extracting lithium and lithium, and composites of borides, oxides, nitrides, sulfides, phosphides, etc. of these metals are preferable. Compound materials are mentioned.

When a carbonaceous material is used as the negative electrode active material, any carbonaceous material can be used. For example, graphite or a surface of graphite coated with amorphous carbon compared to graphite can be used. preferable.
Here, graphite has a lattice plane (002 plane) d value (interlayer distance) of 0.335 nm or more, usually 0.338 nm or less, preferably 0.337 nm, determined by X-ray diffraction by the Gakushin method. The following are preferred.

Furthermore, as for graphite, it is desirable that the crystallite size (Lc) obtained by X-ray diffraction by the Gakushin method is usually 30 nm or more, preferably 50 nm or more, and more preferably 100 nm or more.
The ash content of graphite is usually 1% by weight or less, preferably 0.5% by weight or less, and more preferably 0.1% by weight or less.

  Further, as the graphite surface coated with amorphous carbon, graphite having a d-value of the lattice plane (002 plane) in X-ray diffraction usually 0.335 nm to 0.338 nm as a core material is used. It is preferable to use a carbonaceous material having a larger d value on the lattice plane (002 plane) in X-ray diffraction than the core material. Furthermore, the ratio between the core material and the carbonaceous material having a d-value of the lattice plane (002 plane) in X-ray diffraction adhering to the surface of the core material is usually 99/1 to 80 in terms of weight ratio. / 20 is more preferable. When this is used, a negative electrode which has a high capacity and hardly reacts with the non-aqueous electrolyte can be produced.

  Further, the particle size of the carbonaceous material is arbitrary as long as the effects of the present invention are not impaired, but the median diameter by the laser diffraction / scattering method is usually 1 μm or more, preferably 3 μm or more, more preferably 5 μm or more, further preferably 7 μm or more. On the other hand, the upper limit is usually 100 μm or less, preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less. If the lower limit of the above range is not reached, the specific surface area may become too large, and if the upper limit is exceeded, the specific surface area may become too small.

Further, the specific surface area of the carbonaceous material according to the BET method is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.3 m ² / g or more, preferably 0.5 m ² / g or more, more preferably 0.00. It is 7 m ² / g or more, more preferably 0.8 m ² / g or more. On the other hand, the upper limit is usually 25.0 m ² / g or less, preferably 20.0 m ² / g or less, more preferably 15.0 m ² / g or less, or less and more preferably 10.0 m ² / g. If the lower limit of the above range is not reached, it may not be possible to secure a sufficient area for lithium ion insertion / extraction, and if it exceeds the upper limit, the reactivity with the electrolyte solution may become too high.

Further, the carbonaceous material, when analyzed by Raman spectrum using argon ion laser light, and the peak intensity I _A of the peak P _A in the range of ^{1570cm -1 ~1620cm -1, 1300cm -1 ~1400cm} -1 R value expressed by the ratio of the peak intensity I _B of a peak P _B in the range of (= I _B / I _a) is, usually, good battery characteristics as in the range of 0.01 to 0.7 It is preferable in obtaining.

In this connection, the carbonaceous material, when analyzed by Raman spectrum using argon ion laser light, the half width of the peak in the range of 1570cm ^-1 ~1620cm ^-1, typically 26cm ^-1 or less In order to obtain good battery characteristics, it is preferably 25 cm ⁻¹ or less.

  Further, as the negative electrode active material, an alloy composed of one or more metals capable of inserting and extracting lithium and lithium, or a composite compound such as a boride, oxide, nitride, sulfide, or phosphide of these metals In the case of using materials, as these alloys and composite compound materials, alloys containing a plurality of metal elements may be used, and further composite compounds thereof may be used. For example, a metal alloy or an alloy boride, oxide, nitride, sulfide, phosphide, or other complex compound that is chemically combined may be used.

  Furthermore, among negative electrode active materials made of these alloys and composite compound materials, Si, Sn, Pb, or the like is contained from the viewpoint of increasing the capacity per unit weight of the negative electrode when a non-aqueous electrolyte secondary battery is made. It is preferable to use those, and it is particularly preferable to use those containing Si or Sn.

Moreover, there is no restriction | limiting also in the electrical power collector of a negative electrode, as long as the effect of this invention is not impaired remarkably, a well-known thing can be used arbitrarily. Further, the current collector may be used alone or in any combination of two or more.
The material for the current collector for the negative electrode is not limited, but examples of commonly used materials include steel, copper alloy, nickel, nickel alloy, and stainless steel. Among these, a copper foil is preferable from the viewpoint of easy processing into a thin film and cost.

  In order to improve the binding effect with the active material layer formed on the surface, it is preferable that the surface of the current collector is roughened in advance. Surface roughening methods include blasting, rolling with a rough roll, polishing cloth with a fixed abrasive particle, grinder, emery buff, wire brush equipped with steel wire, etc. Examples thereof include a mechanical polishing method, an electrolytic polishing method, and a chemical polishing method.

  In order to reduce the weight of the current collector and improve the energy density per weight of the non-aqueous electrolyte battery, a perforated current collector such as an expanded metal or a punching metal can be used. This type of current collector can be freely changed in weight by changing its aperture ratio. Further, when an active material layer is formed on both surfaces of this type of current collector, the active material layer is further less likely to peel due to the rivet effect through the hole. However, when the aperture ratio becomes too high, the contact area between the active material layer and the current collector becomes small, so that the adhesive strength may be lowered.

  The thickness of the current collector is usually 1 μm or more, preferably 5 μm or more, and is usually 100 μm or less, preferably 50 μm or less. If the thickness of the current collector is too thick, the capacity of the entire non-aqueous electrolyte secondary battery will be excessively reduced. Conversely, if the current collector is too thin, it may be difficult to handle the current collector.

Furthermore, there is no restriction | limiting in the manufacturing method of a negative electrode, Usually, what is necessary is just to follow a conventional method.
As an example of a method for producing a negative electrode, a negative electrode active material is added with a conductive material, a binder, a thickener, a filler, a solvent, etc. to form a slurry, which is applied to a current collector, dried, and then pressed. And forming a negative electrode active material layer on the current collector by increasing the density.

In this method, the slurry is prepared by adding a binder, a thickener, a filler, a solvent and the like to the negative electrode material. The negative electrode material here is defined as a material including a negative electrode active material and a conductive material.
The content of the negative electrode active material is usually 70 parts by weight or more, preferably 75 parts by weight or more, and usually 97 parts by weight or less, preferably 95 parts by weight or less with respect to 100 parts by weight of the negative electrode material. If the amount of the negative electrode active material is less than this range, the capacity of the negative electrode may be insufficient, and if it is large, the strength of the negative electrode may be insufficient due to a relatively insufficient content of the binder or the like.

  Although there is no restriction | limiting in an electrically conductive material, For example, carbon materials, such as metal materials, such as copper and nickel; Graphite, graphite, carbon black, etc. are mentioned. In particular, it is preferable to use a carbon material as the conductive material because the carbon material acts as an active material. In addition, a electrically conductive material may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  The content of the conductive material is not limited, but is usually 3 parts by weight or more, preferably 5 parts by weight or more, and usually 30 parts by weight or less, preferably 25 parts by weight or less with respect to 100 parts by weight of the negative electrode material. It is desirable. If the content of the conductive material is less than this range, the conductivity may be insufficient. If the content is large, the battery capacity and strength may be decreased due to a relative shortage of the negative electrode active material and the like. .

  Furthermore, as the binder, any material can be used as long as it is a material that is safe with respect to the solvent and the electrolytic solution used at the time of manufacturing the electrode. For example, fluororesins such as polyvinylidene fluoride and polytetrafluoroethylene, polyolefins such as polyethylene and polypropylene, unsaturated polymers such as styrene / butadiene rubber / isoprene rubber and butadiene rubber, and copolymers thereof, ethylene-acrylic acid copolymer Examples thereof include acrylic acid-based polymers such as coalesced polymers and ethylene-methacrylic acid copolymers, and copolymers thereof. In addition, a binder may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

  Further, the content of the binder is not limited, but is usually 0.5 parts by weight or more, preferably 1 part by weight or more and usually 10 parts by weight or less, preferably 8 parts by weight with respect to 100 parts by weight of the negative electrode material. Or less. If the binder content is less than this range, the strength of the negative electrode may be insufficient. If the content is large, the battery capacity and conductivity may be insufficient due to a relative shortage of the negative electrode active material. There is sex.

Furthermore, as the thickener, for example, carboxymethylcellulose, methylcellulose, hydroxymethylcellulose, ethylcellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, and the like can be used. In addition, a thickener may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.
Moreover, although there is no restriction | limiting in content of a thickener, It is preferable to use in the range of 0.5 to 5 weight% normally in a negative electrode active material layer.

Further, as the filler, for example, lauric acid derivatives, TWIN20 (trade name) and the like can be used. In addition, a filler may be used individually by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.
Moreover, although there is no restriction | limiting also in content of a filler, It is preferable to use in the range of 0.5 to 5 weight% normally in a negative electrode active material layer.

Furthermore, although there is no restriction | limiting in the solvent at the time of preparing a slurry, For example, water, NMP (N-methylpyrrolidone), DMF (N, N-dimethylformamide) etc. can be used.
Then, the slurry is applied to a current collector, dried, and then pressed to form a negative electrode active material layer. The density of the negative electrode active material layer after drying and pressing is not limited, but is usually 1.0 g / cm ³ or more.

  In addition, the negative electrode is also a method in which a negative electrode active material added with a binder, a conductive material, or the like is roll-molded as it is to form a sheet electrode, a pellet electrode is formed by compression molding, or a method such as vapor deposition, sputtering, or plating. Or by forming a thin film of an electrode material on the current collector.

[II-3. Positive electrode]
As the positive electrode used in the non-aqueous electrolyte secondary battery of the present invention, any positive electrode can be used as long as it can occlude and release lithium ions as long as the effects of the present invention are not impaired. Usually, a positive electrode in which a positive electrode active material is fixed to a current collector is used as the positive electrode.

  The positive electrode active material is not limited and is arbitrary. For example, transition metal oxide, transition metal and lithium composite oxide (lithium transition metal composite oxide), transition metal sulfide, metal oxide, and other inorganic materials Examples thereof include a compound, lithium metal, lithium alloy, or a composite thereof. In addition, a positive electrode active material may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

Specific examples of the positive electrode active material include transition metal oxides such as MnO, V ₂ O ₅ , V ₆ O ₁₃ and TiO ₂ ; lithium cobalt composite oxide whose basic composition is LiCoO ₂ , lithium nickel which is LiNiO ₂ Lithium transition metal complex oxides such as complex oxides, lithium manganese complex oxides such as LiMn ₂ O ₄ or LiMnO ₂ , lithium nickel manganese cobalt complex oxides, lithium nickel cobalt aluminum complex oxides; transition metals such as TiS and FeS Sulfides; metal oxides such as SnO ₂ and SiO ₂ are listed.

  Among them, lithium transition metal composite oxides, specifically lithium cobalt composite oxide, lithium nickel composite oxide, lithium cobalt nickel composite oxide, lithium nickel manganese cobalt composite oxide, lithium nickel cobalt aluminum composite oxide, etc. Is preferably used because it can achieve both high capacity and high cycle characteristics.

  In addition, lithium transition metal composite oxide is a part of cobalt, nickel or manganese, Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, etc. Substitution with a metal is preferable because the structure can be stabilized.

Moreover, there is no restriction | limiting also in the positive electrode electrical power collector, A well-known thing can be used arbitrarily unless the effect of this invention is impaired remarkably.
The material of the positive electrode current collector is not limited, but examples of commonly used materials include aluminum, titanium, tantalum, and alloys thereof. Of these, aluminum and its alloys are preferable.
In addition, it is preferable to roughen the surface, the point where a perforated type current collector may be used, the thickness of the current collector, etc., and other matters are the same as the current collector of the negative electrode. is there.

Furthermore, there is no restriction | limiting in the manufacturing method of a positive electrode, Usually, what is necessary is just to follow a conventional method.
As an example of the manufacturing method of the positive electrode, as in the case of the negative electrode, a binder, a thickener, a conductive material, a filler, a solvent, etc. are added to the positive electrode active material to form a slurry, which is used as a current collector. An example is a method of forming a negative electrode active material layer on a current collector by applying and drying and then pressing to increase the density. Similarly to the negative electrode, the positive electrode may contain a thickener, a conductive material, a filler, and the like for the purpose of increasing mechanical strength and electrical conductivity.
The density after drying and pressing of the positive electrode active material layer is not limited, but is usually 3.0 g / cm ³ or more.

  As for the positive electrode, similarly to the negative electrode, a positive electrode active material added with a binder or a conductive material is roll-formed as it is to form a sheet electrode, a pellet electrode by compression molding, or vapor deposition / sputtering. It can also be produced by forming a thin film of electrode material on the current collector by a technique such as plating.

[II-4. Separator]
Usually, a separator is interposed between the positive electrode and the negative electrode in order to prevent a short circuit. In this case, the nonaqueous electrolytic solution of the present invention is usually used by impregnating the separator.
There is no restriction | limiting in a separator and a well-known thing can be arbitrarily employ | adopted unless the effect of this invention is impaired remarkably. Accordingly, the material and shape of the separator are not particularly limited, but it is preferable to use a porous sheet or a nonwoven fabric that is formed of a material that is stable with respect to the non-aqueous electrolyte of the present invention and has excellent liquid retention.

  As a material for the separator, for example, polyolefin such as polyethylene and polypropylene, polytetrafluoroethylene, polyethersulfone, glass filter and the like can be used. Of these, glass filters and polyolefins are preferred, and polyolefins are more preferred. In addition, these materials may be used individually by 1 type, and may use 2 or more types together by arbitrary combinations and ratios.

  Moreover, although the thickness of a separator is arbitrary, it is 1 micrometer or more normally, Preferably it is 5 micrometers or more, More preferably, it is 10 micrometers or more, and is 50 micrometers or less normally, Preferably it is 40 micrometers or less, More preferably, it is 30 micrometers or less. If the separator is too thin, the insulation and mechanical strength may be reduced, and if it is too thick, not only the battery performance such as rate characteristics may be reduced, but also the non-aqueous electrolyte secondary battery as a whole. The energy density can be reduced.

  Furthermore, when a porous material such as a porous sheet or nonwoven fabric is used as the separator, the porosity of the separator is arbitrary, but is usually 20% or more, preferably 35% or more, more preferably 45% or more, Usually, it is 90% or less, preferably 85% or less, more preferably 75% or less. If the porosity is too small, the membrane resistance increases and the rate characteristics tend to deteriorate. On the other hand, if it is too large, the mechanical strength of the separator is lowered and the insulating property tends to be lowered.

  Moreover, although the average pore diameter of a separator is also arbitrary, it is 0.5 micrometer or less normally, Preferably it is 0.2 micrometer or less, and is 0.05 micrometer or more normally. If the average pore diameter is too large, a short circuit is likely to occur, and if it is too small, the membrane resistance increases and the rate characteristics may be degraded.

[II-5. Exterior body]
The non-aqueous electrolyte secondary battery of the present invention is usually configured by housing the non-aqueous electrolyte, the negative electrode, the positive electrode, the separator, and the like in an exterior body. There is no restriction | limiting in this exterior body, As long as the effect of this invention is not impaired remarkably, a well-known thing can be employ | adopted arbitrarily.

The material of the exterior body is arbitrary, but usually, for example, nickel-plated iron, stainless steel, aluminum or an alloy thereof, nickel, titanium, or the like is used.
The shape of the exterior body is also arbitrary, and may be any of a cylindrical shape, a square shape, a laminate shape, a coin shape, a large size, and the like.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to the examples, and can be arbitrarily modified without departing from the gist of the present invention.

[Examples 1 to 24 and Comparative Examples 1 to 4]
In Examples 1 to 24 and Comparative Examples 1 to 4, non-aqueous electrolyte secondary batteries were assembled and evaluated in the following procedure, and the results are shown in Tables 1 and 2.

[Production of positive electrode]
As a positive electrode active material, LiCoO ₂ (Nippon Chemical Industry Co., Ltd. “C5”) 85% by weight, carbon black (Electrochemical Industry Co., Ltd., trade name “Denka Black”) 6% by weight, and polyvinylidene fluoride (Kureha Chemical Co., Ltd.) (Name "KF-1000") was added and mixed with 9% by weight, and dispersed in N-methyl-2-pyrrolidone to form a slurry, on a positive electrode current collector aluminum foil having a thickness of 20 μm. It was applied uniformly so as to be 90% of the theoretical capacity of the negative electrode to be used, dried at 100 ° C. for 12 hours, and then punched into a disk shape having a diameter of 12.5 mm to obtain a positive electrode.

(Production of negative electrode)
<Production of graphite negative electrode>
83.5 parts by weight of an N-methylpyrrolidone solution containing 12% by weight of PVDF (polyvinylidene fluoride) in 100 parts by weight of artificial graphite powder (trade name “KS-6”, manufactured by Timkar Co., Ltd.), and N-methylpyrrolidone 50 A mixture of parts by weight with a disperser in a slurry form is uniformly applied onto a negative electrode current collector 18 μm thick copper foil, and after drying, the electrode density is about 1.5 g / cm ^3. And then punched into a disk shape having a diameter of 12.5 μm to obtain a graphite negative electrode (graphite negative electrode).

<Preparation of silicon alloy negative electrode>
As the non-carbon material of the negative electrode active material, 73.2 parts by weight of silicon and 8.1 parts by weight of copper were used. To this, artificial graphite powder (trade name “KS-6”, manufactured by Timkar Co., Ltd.), 13.3% by weight, , 54.2 parts by weight of an N-methylpyrrolidone solution containing 12% by weight of PVDF and 50 parts by weight of N-methylpyrrolidone were mixed with a disperser to form a slurry, and the thickness of the negative electrode current collector was 18 μm. It is uniformly coated on the copper foil, dried, pressed to have an electrode density of about 1.5 g / cm ³ , and then punched into a disk shape having a diameter of 12.5 mm to form a silicon alloy negative electrode (silicon alloy Negative electrode).

(Preparation of non-aqueous electrolyte)
For each of Examples 1 to 24 and Comparative Examples 1 to 4, ethylene carbonate (EC) and various carbonate compounds (Examples 1 to 5) so that the compositions of the non-aqueous electrolytes are as shown in Tables 1 and 2, respectively. , 13 to 17 were prepared by dissolving LiPF ₆ as an electrolyte to a concentration of 1 mol / liter in a solution (non-aqueous solvent) in which a specific chain carbonate) was mixed at each volume ratio. Moreover, about Examples 6-10 and Examples 18-22, the various predetermined carbonate was added to the electrolyte solution used in Example 2 and Example 14 as an additive in the ratio shown in Tables 1 and 2, and it was not. A water electrolyte was prepared. For Examples 11 and 12 and Examples 23 and 24, various specific chain carbonates were added as additives to the electrolytes used in Comparative Examples 2 and 4 at the ratios shown in Tables 1 and 2. A non-aqueous electrolyte was prepared.

  In Tables 1 and 2, the indication in parentheses in the electrolyte column represents the concentration of the electrolyte in the non-aqueous electrolyte solution, and the indication in parentheses in the non-aqueous solvent column is the non-aqueous solvent used for the non-aqueous electrolyte solution. Represents the mixing volume ratio of ethylene carbonate and various carbonate compounds, and the indication in parentheses in the column of additive represents the concentration of the additive (specific chain carbonate) in the non-aqueous solvent. In Tables 1 and 2, “DFEMC” represents 2,2-difluoroethyl methyl carbonate, “DFEEC” represents 2,2-difluoroethyl ethyl carbonate, and “DFEPC” represents 2,2-difluoroethyl-n. Represents propyl carbonate, “BDFEC” represents bis (2,2-difluoroethyl) carbonate, “FEC” represents fluoroethylene carbonate, “VC” represents vinylene carbonate, “DFEC” represents 4,5- It represents difluoroethylene carbonate, “EMC” represents ethyl methyl carbonate, and “DEC” represents diethyl carbonate.

[Production of coin cell]
Using the above positive electrode and negative electrode and the non-aqueous electrolyte prepared in each of the examples and comparative examples, the positive electrode is housed in a stainless steel can that also serves as the positive electrode conductor, and the non-aqueous electrolyte is placed thereon. The negative electrode was placed through an impregnated polyethylene separator. The can body and a sealing plate serving also as a negative electrode conductor were caulked and sealed via an insulating gasket to produce a coin-type cell.
In Examples 1 to 12 and Comparative Examples 1 and 2, a silicon alloy negative electrode was used as the negative electrode, and in Examples 13 to 24 and Comparative Examples 3 and 4, a graphite negative electrode was used as the negative electrode.

[Evaluation of coin cell]
At 25 ° C., one cycle of charging end voltage 4.2V, constant current 3 mA, charging end current 0.15 μA constant current constant voltage charging and discharging end voltage 3.0 V, constant current 3 mA constant current discharge As shown in FIG. At this time, the discharge capacity at the 10th cycle was measured in the first cycle, and the example and comparative example using the silicon alloy negative electrode, and the discharge capacity at the 100th cycle was measured in the example and comparative example using the graphite negative electrode. The capacity retention rate in the cycle was calculated by the following formula. Note that the capacity was the capacity per unit weight of the negative electrode active material.

  From Tables 1 and 2, Examples 1 to 12 and Examples 13 to 24 containing the specific chain carbonate have a capacity after cycle more than Comparative Examples 1 and 2 and Comparative Examples 3 and 4 not containing the specific chain carbonate. It can be seen that the retention rate is high and the cycle characteristics are excellent.

The non-aqueous electrolyte and non-aqueous electrolyte secondary battery of the present invention can be widely used in any industrial field, but have excellent long-term charge / discharge cycle characteristics. PC, mobile PC, electronic book player, mobile phone, mobile fax, mobile copy, mobile printer, headphone stereo, video movie, LCD TV, handy cleaner, portable CD player, mini-disc, walkie-talkie, electronic notebook, calculator, memory card Suitable for portable tape recorders, radios, backup power supplies, motors, lighting equipment, toys, game equipment, watches, strobes, cameras, power load leveling, electric bicycles, electric scooters, electric cars, etc. is there.

Claims (8)

A nonaqueous electrolytic solution containing a chain carbonate represented by the following formula (1).

(In the above formula (1), X independently represents hydrogen or an arbitrary group. R represents an alkyl group which may have a substituent. Further, n represents an integer of 0 or more.) In the above formula (1), R is

The non-aqueous electrolyte solution according to claim 1, wherein the non-aqueous electrolyte solution is a group different from. The non-aqueous electrolyte solution according to claim 1, wherein the chain carbonate is bis (2,2-difluoroethyl) carbonate. In the said Formula (1), n is an integer greater than or equal to 0-7, The non-aqueous electrolyte solution of any one of Claims 1-3 characterized by the above-mentioned. The non-aqueous electrolyte solution according to any one of claims 1 to 4, comprising a carbonate having at least one of an unsaturated bond and a halogen atom (excluding the chain carbonate). The concentration of the carbonate having at least one of the unsaturated bond and the halogen atom in the non-aqueous electrolytic solution is 0.01 wt% or more and 70 wt% or less. Non-aqueous electrolyte. The carbonate having at least one of the unsaturated bond and the halogen atom is at least one carbonate selected from the group consisting of vinylene carbonate, vinyl ethylene carbonate, fluoroethylene carbonate, difluoroethylene carbonate, and derivatives thereof. The non-aqueous electrolyte solution according to claim 5 or 6, wherein A negative electrode and a positive electrode capable of inserting and extracting lithium ions;
A non-aqueous electrolyte secondary battery comprising the non-aqueous electrolyte solution according to claim 1.