JP5134783B2 - Nonaqueous electrolyte for battery and nonaqueous electrolyte battery provided with the same - Google Patents

Description

  The present invention relates to a non-aqueous electrolyte for a battery and a non-aqueous electrolyte battery including the same, and particularly includes an ionic liquid containing phosphorus and nitrogen in a cation portion, and is safe from non-ignition / flammability. It relates to a water electrolyte.

  In recent years, there has been a demand for a lightweight, long-life, high-energy-density battery as a main power source or auxiliary power source for electric vehicles and fuel cell vehicles, or as a power source for small electronic devices. In contrast, a non-aqueous electrolyte battery using lithium as a negative electrode active material is known as one of batteries having a high energy density because the electrode potential of lithium is the lowest among metals and the electric capacity per unit volume is large. Many types of batteries, whether primary batteries or secondary batteries, have been actively researched, and some have been put into practical use and supplied to the market. For example, non-aqueous electrolyte primary batteries are used as power sources for cameras, electronic watches, and various memory backups. In addition, non-aqueous electrolyte secondary batteries are used as drive power sources for notebook computers and mobile phones, and are also being considered for use as main power sources or auxiliary power sources for electric vehicles and fuel cell vehicles. .

  In these non-aqueous electrolyte batteries, lithium as the negative electrode active material reacts violently with compounds having active protons such as water and alcohol, so that the electrolyte used in the batteries is non-ester compounds and ether compounds. Limited to protic organic solvents. However, although the aprotic organic solvent has low reactivity with the lithium of the negative electrode active material, for example, when a battery is short-circuited, a large current flows suddenly, and when the battery abnormally generates heat, it is vaporized and decomposed. Therefore, there is a high risk of generating gas, causing the battery to rupture or ignite due to the generated gas and heat, and sparks generated during a short circuit.

  On the other hand, since the report of Wilkes et al. In 1992, an ionic liquid has attracted attention as a substance that is liquid at room temperature and has excellent ionic conductivity. In the ionic liquid, the cation and the anion are combined by electrostatic attraction, the number of ion carriers is very large, and the viscosity is relatively low, so that the ion mobility is high even at room temperature. It has the characteristic that the property is very high. In addition, since the ionic liquid is composed only of cations and anions, the boiling point is high and the temperature range in which the liquid state can be maintained is very wide. Furthermore, since the ionic liquid has almost no vapor pressure, it has low flammability and excellent thermal stability (see Non-Patent Documents 1 and 2). Due to these various advantages, application of ionic liquids to the electrolytes of non-aqueous electrolyte secondary batteries has recently been studied (see Patent Documents 1 and 2).

JP 2004-111294 A JP 2004-146346 A J. Electrochem. Soc., 144 (1997) 3881 “Functional creation and application of ionic liquids”, NTS, (2004)

  As described above, the conventional ionic liquid has low flammability, but since it is a liquid at room temperature and usually contains an organic group, there is a risk of combustion. It was found that the risk of ignition and ignition of the electrolyte could not be reduced sufficiently.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art and provide a safe non-aqueous electrolyte for a battery without the risk of ignition and ignition. Another object of the present invention is to provide a non-aqueous electrolyte battery having such an electrolyte and having high safety.

  As a result of intensive studies to achieve the above object, the present inventors have added an ionic liquid containing phosphorus and nitrogen in the cation part to the electrolytic solution, or constituted the electrolytic solution only from the ionic liquid and a supporting salt. The risk of non-aqueous electrolyte combustion can be greatly reduced, and the safety of the non-aqueous electrolyte battery can be greatly improved by applying the electrolyte to the non-aqueous electrolyte battery. The headline and the present invention have been completed.

That is, the battery non-aqueous electrolyte of the present invention contains an ionic liquid composed of a cation part and an anion part and a supporting salt, the cation part of the ionic liquid contains phosphorus and nitrogen, and the ionic liquid contains The following general formula (I):
(NPR ¹ ₂ ) _n ... (I)
[Wherein R ¹ is independently a halogen element or a monovalent substituent, and at least one R ¹ is represented by the following general formula (II):
_{^{-N + R 2 3 X - ···}} (II)
Wherein R ² is each independently a monovalent substituent or hydrogen, provided that at least one R ² is not hydrogen and R ² may be bonded to each other to form a ring; X ^- is be ionic substituent represented by represents a monovalent anion); n is characterized by being represented by a 3].

  A preferred example of the non-aqueous electrolyte for a battery of the present invention is preferably composed only of the ionic liquid and a supporting salt.

  The battery non-aqueous electrolyte of the present invention may further contain an aprotic organic solvent. Here, when the nonaqueous electrolytic solution for battery of the present invention contains an aprotic organic solvent, the nonaqueous electrolytic solution for battery preferably contains 5% by volume or more of the ionic liquid.

Further, R ¹ in the general formula (I), at least one of an ionic substituent represented by the general formula (II), it is preferable others are fluorine.

  Moreover, the non-aqueous electrolyte battery of the present invention comprises the above-described non-aqueous electrolyte for a battery, a positive electrode, and a negative electrode.

According to the present invention, it is possible to contain the ionic liquid represented by phosphorus and nitrogen only contains and Formula cation portion (I), to provide a low risk of burning the battery for a non-aqueous electrolyte solution . In addition, a non-aqueous electrolyte battery having such an electrolyte and having high safety can be provided.

<Non-aqueous electrolyte for batteries>
Below, the non-aqueous electrolyte for batteries of the present invention will be described in detail. The non-aqueous electrolyte for a battery of the present invention contains an ionic liquid composed of a cation part and an anion part and a supporting salt, the cation part of the ionic liquid contains phosphorus and nitrogen, and the ionic liquid is the above general formula It is represented by (I) . Since the cation part of the ionic liquid contained in the nonaqueous electrolyte for a battery of the present invention is decomposed to generate nitrogen gas, phosphate ester, etc., there is a risk that the electrolyte will burn by the action of the generated nitrogen gas In addition, the chain decomposition of the polymer material constituting the battery is suppressed by the action of the generated phosphoric acid ester and the like, so that the risk of ignition and ignition of the battery can be effectively reduced. Further, when the cation portion of the ionic liquid contains halogen, the halogen functions as an active radical scavenger in the unlikely event of combustion, reducing the risk of combustion of the electrolyte. Further, when the cation portion of the ionic liquid contains an organic substituent, it produces a carbide (char) on the separator at the time of combustion, and has an oxygen blocking effect.

The ionic liquid constituting the nonaqueous electrolyte for a battery of the present invention has at least a melting point of 50 ° C. or lower and preferably a melting point of 20 ° C. or lower. The ionic liquid is composed of a cation part and an anion part, and the cation part and the anion part are bonded by electrostatic attraction. Wherein the ionic liquid, phosphorus cation - have a nitrogen double bond, an ionic compound represented by the general formula (I).

Since the compound of the general formula (I) is a kind of cyclic phosphazene compound having a plurality of phosphorus-nitrogen double bonds, it has a high combustion suppressing effect, and at least one of R ¹ is an ion of the formula (II). Since it is an ionic substituent, it has ionicity.

R ¹ in the general formula (I) is independently a halogen element or a monovalent substituent, provided that at least one R ¹ is an ionic substituent represented by the general formula (II). It is. Here, preferred examples of the halogen element in R ¹ include fluorine, chlorine, bromine and the like, and among these, fluorine is particularly preferred. Examples of the monovalent substituent in R ¹ include an alkoxy group, an alkyl group, an aryloxy group, an aryl group, a carboxyl group, and an acyl group. Examples of the alkoxy group include a methoxy group, an ethoxy group, a methoxyethoxy group, a propoxy group, an allyloxy group containing a double bond, a vinyloxy group, and the like, and an alkoxy-substituted alkoxy group such as a methoxyethoxy group and a methoxyethoxyethoxy group. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, and a pentyl group. Examples of the aryloxy group include a phenoxy group, a methylphenoxy group, and a methoxyphenoxy group. Examples of the aryl group include a phenyl group, a tolyl group, and a naphthyl group. Examples of the acyl group include a formyl group, an acetyl group, a propionyl group, a butyryl group, an isobutyryl group, and a valeryl group. Note that the hydrogen element in the monovalent substituent is preferably substituted with a halogen element, and preferred examples of the halogen element include fluorine, chlorine, bromine and the like.

N in the above general formula (I), from the viewpoint of easy availability of raw materials, it is 3.

The substituent represented by the general formula (II) is formed by bonding —NR ² ₃ and X mainly by electrostatic attraction. Therefore, the compound of formula (I) having an ionic substituent of formula (II) has ionicity.

R ² in the above general formula (II) is each independently a monovalent substituent or hydrogen, provided that at least one R ² is not hydrogen and R ² is bonded to each other to form a ring. May be. Here, examples of the monovalent substituent in R ² include an alkyl group and an aryl group. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, and a pentyl group. Examples of the aryl group include a phenyl group, a tolyl group, and a naphthyl group. In addition, when a plurality of R ² are bonded to each other to form a ring, any two of the three R ² are bonded to form an aziridine ring, azetidine ring, pyrrolidine ring, piperidine ring or the like. Examples thereof include a cycloalkane ring and an azacycloalkanone ring having a structure in which a methylene group of the azacycloalkane ring is replaced with a carbonyl group. Examples of the ring formed by combining three R ² include a pyridine ring. It is done. Note that the hydrogen element in the monovalent substituent may be substituted with a halogen element or the like.

X ⁻ in the general formula (II) represents a monovalent anion. As the monovalent anion in X ⁻ of the formula (II), F ⁻ , Cl ⁻ , Br ⁻ , I ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , CF ₃ SO ₃ ⁻ , ( CF ₃ SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , (C ₃ F ₇ SO ₂ ) ₂ N ⁻ , (CF ₃ SO ₂ ) (C ₂ F ₅ SO ₂ ) N ⁻ , (CF ₃ SO ₂ ) (C ₃ F ₇ SO ₂ ) N ⁻ , (C ₂ F ₅ SO ₂ ) (C ₃ F ₇ SO ₂ ) N ^{− and the} like.

In the ionic compound of the above formula (I), at least one R ¹ is an ionic substituent of the above formula (II), but the other is preferably fluorine from the viewpoint of nonflammability of the ionic compound. .

The method for producing the ionic compound is not particularly limited. For example, the following general formula (III):
(NPR ³ ₂ ) _n ... (III)
Wherein R ³ is independently a halogen element or a monovalent substituent, and at least one R ³ is chlorine; n is 3 , and a cyclic phosphazene compound represented by the following general formula: (IV):
NR ² ₃ ... (IV)
[In the formula, R ² is as defined above] By reacting with a primary, secondary or tertiary amine represented by the following general formula (V):
(NPR ⁴ ₂ ) _n ... (V)
[Wherein, R ⁴ is independently a halogen element or a monovalent substituent, and at least one R ⁴ is represented by the following general formula (VI):
_{^{-N + R 2 3 Cl - ···}} (VI)
(Wherein R ² is as defined above); n is as defined above] (ie, represented by formula (I) above). And an ionic compound in which X ⁻ in the general formula (II) is Cl 2 ⁻ can be generated.

Furthermore, the chlorine ion of the ionic compound represented by the general formula (V) can be appropriately substituted with another monovalent anion, for example, the ionic compound represented by the general formula (V) The following general formula (VII):
A ⁺ X ^- ··· (VII)
[Wherein A ⁺ represents a monovalent cation, and X ⁻ represents a monovalent anion] is reacted (ion exchange reaction) with a salt represented by the above general formula. An ionic compound represented by (I) can be produced.

  Note that the ionic compound represented by the general formula (V) can be produced simply by mixing the cyclic phosphazene compound represented by the general formula (III) and the amine represented by the general formula (IV). However, since the produced ionic compound of formula (V) may be unstable and difficult to isolate, a two-phase system composed of an aqueous phase and an organic phase is represented by the above general formula (III). It is preferable that the cyclic phosphazene compound and the amine represented by the general formula (IV) are added and reacted to produce the ionic compound represented by the general formula (V). In this method, the cyclic phosphazene compound of formula (III) and the amine of formula (IV) are mainly present in the organic phase, while the resulting compound of formula (V) is mainly present in the aqueous phase due to its ionic nature. Therefore, after separating the aqueous phase and the organic phase, the ionic compound of formula (V) can be isolated by drying the water of the aqueous phase by a known method, and the isolated formula (V The ionic compound of) exists stably even in the atmosphere.

In the general formula (III), each R ³ is independently a halogen element or a monovalent substituent, and at least one R ³ is chlorine. Here, since the amine of the formula (IV) is added to the portion of the formula (III) where R ³ is chlorine, the number of chlorines bonded to the phosphorus of the skeleton of the cyclic phosphazene compound of the formula (III) as the starting material By adjusting, the number of introduced ionic substituents represented by the formula (VI) in the ionic compound of the formula (V) can be controlled.

In R ³ of the general formula (III), examples of the halogen element include fluorine, bromine and the like in addition to chlorine, and among these, chlorine and fluorine are preferable. On the other hand, as the monovalent substituent in R ³ , those exemplified in the section of the monovalent substituent in R ¹ can be similarly exemplified. Further, in formula (III), n, from the viewpoint of easy availability, a 3.

The cyclic phosphazene compound represented by the general formula (III) is, for example, a commercially available phosphazene compound in which R ³ in the formula (III) is all chlorine as a starting material. Then, after introducing an alkoxy group, an amine group or the like into the target chlorine substitution site, chlorinating again with a chlorinating agent such as HCl or phosgene, or R ³ in the formula (III) to be used is It can be synthesized by a method of adding a necessary amount of a fluorinating agent after calculating the equivalent amount of fluorine to be introduced to commercially available phosphazene compounds which are all chlorine. Here, the number of chlorine in R ³ in the formula (III) can be controlled by changing the amount of chlorinating agent used in rechlorination, the amount of the fluorinating agent used in fluorination, and the reaction conditions.

In the general formula (IV), R ² is a R ² as defined in the above formula (II), are each independently a monovalent substituent or hydrogen, provided that at least one R ² is hydrogen And R ² may be bonded to each other to form a ring. Examples of the monovalent substituent in R ² of formula (IV), can similarly be illustrated those which have been exemplified in the section of the monovalent substituent in R ² of Formula (II), also, the formula (IV) any two of the three R ² as the ring ring and three R ² formed by the bonding formed by combining any two of the three R ² of formula (II) is formed by bonding What was illustrated by the term of the ring formed by combining a ring and three R < ² > can be mentioned similarly. Specific examples of the amine represented by the formula (IV) include aliphatic tertiary amines such as trimethylamine, triethylamine, tripropylamine, and tributylamine, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, and the like. And cyclic tertiary amines, dialkyl-substituted anilines such as dimethylaniline, aromatic tertiary amines such as pyridine, and aromatic primary amines such as aniline. Among these, tertiary amines are preferred.

In the general formula (V), each R ⁴ is independently a halogen element or a monovalent substituent, and at least one R ⁴ is an ionic substituent represented by the general formula (VI). Examples of the halogen element in R ⁴ include fluorine, chlorine, bromine and the like. In addition, a part of R ⁴ can be changed to chlorine by adjusting the amount of the amine of the formula (IV). On the other hand, as the monovalent substituent in R ⁴ , those exemplified in the section of the monovalent substituent in R ¹ can be similarly exemplified. Further, n in formula (V), from the viewpoint of availability of raw material, which is 3.

In the general formula (VI), R ² is, by R ² as defined in the above formula (II), are each independently a monovalent substituent or hydrogen, provided that at least one R ² is hydrogen And R ² may be bonded to each other to form a ring. Examples of the monovalent substituent in R ² of formula (VI), can similarly be illustrated those which have been exemplified in the section of the monovalent substituent in R ² of Formula (II), also, the formula (VI) any two of the three R ² as the ring ring and three R ² formed by the bonding formed by combining any two of the three R ² of formula (II) is formed by bonding What was illustrated by the term of the ring formed by combining a ring and three R < ² > can be mentioned similarly.

In the production of the ionic compound of the formula (V), the amount of the amine of the formula (IV) can be appropriately selected according to the amount of the amine introduced, for example, R in the cyclic phosphazene compound of the formula (III) The range of 1 to 2.4 mol per mol of chlorine in ³ is preferred.

  Further, the reaction temperature in the reaction of the cyclic phosphazene compound of the formula (III) and the amine of the formula (IV) is not particularly limited, but is preferably in the range of 20 ° C to 80 ° C, and the reaction is sufficiently performed even at room temperature. proceed. Further, the reaction pressure is not particularly limited, and the reaction can be performed under atmospheric pressure.

  In the two-phase system composed of the aqueous phase and the organic phase, the organic solvent used in the organic phase is not miscible with water and can dissolve the cyclic phosphazene compound of formula (III) and the amine of formula (IV). Those having low polarity such as chloroform and toluene are preferred. The amount of the aqueous phase and the organic phase used is not particularly limited, and the volume of the aqueous phase is preferably in the range of 0.2 to 5 mL with respect to 1 mL of the cyclic phosphazene compound of the formula (III). The volume is preferably in the range of 2 to 5 mL with respect to 1 mL of the cyclic phosphazene compound of the formula (III).

In the general formula (VII), A ⁺ represents a monovalent cation, and X ⁻ represents a monovalent anion. Examples of the monovalent cation in A ⁺ in the formula (VII) include Ag ⁺ and Li ⁺ . Further, as the monovalent anion in X ⁻ of the formula (VII), monovalent anions other than Cl ⁻ , specifically, BF ₄ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , CF ₃ SO ₃ ^- _{other, (CF 3 SO 2) 2} N -, (C 2 F 5 SO 2) 2 N -, (C 3 F 7 SO 2) 2 N -, (CF 3 SO 2) (C 2 Examples thereof include imide ions such as F ₅ SO ₂ ) N ⁻ , (CF ₃ SO ₂ ) (C ₃ F ₇ SO ₂ ) N ⁻ and (C ₂ F ₅ SO ₂ ) (C ₃ F ₇ SO ₂ ) N ⁻ . Here, when A ⁺ is Li ⁺ , X ⁻ is preferably an imide ion. In contrast to Li ⁺ , which has a small ionic radius, the imide ion has a large ionic radius, so it reacts well due to the influence of the difference in ionic radius between cation and anion (soft / hard base / acid relationship). This is because the substitution reaction proceeds. On the other hand, when A ⁺ is Ag ⁺ , almost all anions can be used. When Ag ⁺ X ⁻ is used as the salt of the formula (VII), the impurities can be easily removed because AgCl is precipitated.

  In the production of the ionic compound of the formula (I), the amount of the salt of the formula (VII) used can be appropriately selected according to the amount of chlorine ions of the ionic compound of the formula (V). The range of 1 to 1.5 mol is preferable per 1 mol of chloride ions of the ionic compound.

  The reaction temperature in the reaction of the ionic compound of formula (V) and the salt of formula (VII) is not particularly limited, but is preferably in the range of room temperature to 50 ° C., and the reaction proceeds sufficiently even at room temperature. To do. Further, the reaction pressure is not particularly limited, and the reaction can be performed under atmospheric pressure.

The reaction of the ionic compound of formula (V) with the salt of formula (VII) is preferably carried out in an aqueous phase. In the reaction of the ionic compound of the above formula (V) with the silver salt represented by the formula (VII) and A ⁺ is Ag ⁺ , silver chloride is produced as a by-product, Since the solubility in water is very low, by-products can be easily separated when the reaction is carried out in an aqueous phase. Isolation from the aqueous phase of the ionic compound of formula (I), which is the target substance, may be carried out by evaporating the water in the aqueous phase by a known method. The volume of the aqueous phase is not particularly limited, but is preferably in the range of 2 to 5 mL with respect to 1 mL of the ionic compound of the formula (V).

As the supporting salt used in the nonaqueous electrolytic solution for a battery of the present invention, a supporting salt serving as an ion source of lithium ions is preferable. The supporting salt is not particularly limited, and for example, LiClO ₄ , LiBF ₄ , LiPF ₆ , LiCF ₃ SO ₃ , LiAsF ₆ , LiC ₄ F ₉ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N and Li ( Preferable examples include lithium salts such as C ₂ F ₅ SO ₂ ) ₂ N. These supporting salts may be used alone or in combination of two or more. The concentration of the supporting salt in the battery non-aqueous electrolyte of the present invention is preferably in the range of 0.2 to 1.5 mol / L (M), more preferably in the range of 0.5 to 1 mol / L. If the concentration of the supporting salt is less than 0.2 mol / L, the conductivity of the electrolyte cannot be sufficiently ensured, and the discharge characteristics and charging characteristics of the battery may be hindered. Since the viscosity of the electrolytic solution increases and the mobility of lithium ions cannot be ensured sufficiently, the conductivity of the electrolytic solution cannot be sufficiently ensured in the same manner as described above, which may hinder battery discharge characteristics and charge characteristics. .

  The battery non-aqueous electrolyte of the present invention preferably comprises only the ionic liquid and the supporting salt, but may contain known additives used for the battery non-aqueous electrolyte depending on the purpose. it can. Specifically, the nonaqueous electrolytic solution for a battery of the present invention can contain an aprotic organic solvent. Examples of the aprotic organic solvent include dimethyl carbonate (DMC), diethyl carbonate (DEC), diphenyl carbonate, ethyl methyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), γ-butyrolactone (GBL), γ Preferred examples include esters such as valerolactone and methyl formate (MF), and ethers such as 1,2-dimethoxyethane (DME) and tetrahydrofuran (THF). Among these, propylene carbonate, 1,2-dimethoxyethane, and γ-butyrolactone are preferable as the aprotic organic solvent for the non-aqueous electrolyte of the primary battery, while for the non-aqueous electrolyte of the secondary battery. As the aprotic organic solvent, ethylene carbonate, propylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate and methyl formate are preferable. Cyclic esters are preferred in that they have a high relative dielectric constant and excellent solubility of the supporting salt, while chain esters and chain ethers have low viscosity, so It is suitable in terms of lowering the viscosity. These aprotic organic solvents may be used alone or in combination of two or more. Here, the content of the ionic liquid in the electrolytic solution is preferably 5% by volume or more from the viewpoint of the safety of the electrolytic solution.

<Nonaqueous electrolyte battery>
Next, the nonaqueous electrolyte battery of the present invention will be described in detail. The non-aqueous electrolyte battery of the present invention includes the above-described non-aqueous electrolyte for a battery, a positive electrode, and a negative electrode, and is usually used in the technical field of non-aqueous electrolyte batteries such as a separator as necessary. Other members may be provided, and the primary battery or the secondary battery may be used.

The positive electrode active material of the non-aqueous electrolyte battery of the present invention is partially different between the primary battery and the secondary battery. For example, as the positive electrode active material of the non-aqueous electrolyte primary battery, fluorinated graphite [(CF _x ) _n ], MnO ₂ (which may be electrochemical synthesis or chemical synthesis), V ₂ O ₅ , MoO ₃ , Ag ₂ CrO ₄ , CuO, CuS, FeS ₂ , SO ₂ , SOCl ₂ , TiS _2, etc. Among these, MnO ₂ and fluorinated graphite are preferable from the viewpoints of high capacity and high safety, and high discharge potential and excellent wettability of the electrolytic solution. These positive electrode active materials may be used individually by 1 type, and may use 2 or more types together.

On the other hand, as the positive electrode active material of the non-aqueous electrolyte secondary battery, metal oxides such as V ₂ O ₅ , V ₆ O ₁₃ , MnO ₂ , MnO ₃ , LiCoO ₂ , LiNiO ₂ , LiMn ₂ O ₄ , LiFeO _{2 are used.} Preferable examples include lithium-containing composite oxides such as LiFePO ₄ , metal sulfides such as TiS ₂ and MoS ₂ , and conductive polymers such as polyaniline. The lithium-containing composite oxide may be a composite oxide containing two or three transition metals selected from the group consisting of Fe, Mn, Co, and Ni. In this case, the composite oxide includes: LiFe _x Co _y Ni (wherein, 0 ≦ x <1,0 ≦ y <1,0 <x + y ≦ 1) (1-xy) O 2, or represented by LiMn _x Fe _y O _2-xy like. Among these, LiCoO ₂ , LiNiO ₂ , and LiMn ₂ O ₄ are particularly preferable in terms of high capacity, high safety, and excellent electrolyte wettability. These positive electrode active materials may be used individually by 1 type, and may use 2 or more types together.

  The negative electrode active material of the nonaqueous electrolyte battery of the present invention is partially different between the primary battery and the secondary battery. For example, as the negative electrode active material of the nonaqueous electrolyte primary battery, lithium metal itself, lithium alloy, etc. Is mentioned. Examples of the metal that forms an alloy with lithium include Sn, Pb, Al, Au, Pt, In, Zn, Cd, Ag, and Mg. Among these, Al, Zn, and Mg are preferable from the viewpoints of rich reserves and toxicity. These negative electrode active materials may be used individually by 1 type, and may use 2 or more types together.

  On the other hand, as the negative electrode active material of the non-aqueous electrolyte secondary battery, lithium metal itself, an alloy of lithium and Al, In, Sn, Si, Pb, Zn, or the like, or a carbon material such as graphite doped with lithium is preferable. Among these, carbon materials such as graphite are preferable, and graphite is particularly preferable in that it is higher in safety and excellent in wettability of the electrolytic solution. Here, examples of graphite include natural graphite, artificial graphite, mesophase carbon microbeads (MCMB), and the like, and widely include graphitizable carbon and non-graphitizable carbon. These negative electrode active materials may be used individually by 1 type, and may use 2 or more types together.

  The positive electrode and the negative electrode can be mixed with a conductive agent and a binder as necessary. Examples of the conductive agent include acetylene black, and the binder includes polyvinylidene fluoride (PVDF) and polytetrafluoro. Examples include ethylene (PTFE), styrene / butadiene rubber (SBR), carboxymethyl cellulose (CMC), and the like. These additives can be used at a blending ratio similar to the conventional one.

  Moreover, there is no restriction | limiting in particular as a shape of the said positive electrode and a negative electrode, It can select suitably from well-known shapes as an electrode. For example, a sheet shape, a columnar shape, a plate shape, a spiral shape, and the like can be given.

  Other members that can be used in the non-aqueous electrolyte battery of the present invention include a separator that is interposed between positive and negative electrodes in a role of preventing current short-circuiting due to contact between both electrodes in the non-aqueous electrolyte battery. As the material of the separator, it is possible to reliably prevent contact between the two electrodes and to allow the electrolyte to pass through or to contain, for example, synthesis of polytetrafluoroethylene, polypropylene, polyethylene, cellulose, polybutylene terephthalate, polyethylene terephthalate, etc. Preferred examples include resin non-woven fabrics and thin layer films. Of these, polypropylene or polyethylene microporous films having a thickness of about 20 to 50 μm, cellulose-based films, polybutylene terephthalate, polyethylene terephthalate, and the like are particularly suitable. In the present invention, in addition to the separators described above, known members that are normally used in batteries can be suitably used.

  The form of the non-aqueous electrolyte battery of the present invention described above is not particularly limited, and various known forms such as a coin-type, button-type, paper-type, square-type or spiral-type cylindrical battery are suitable. Can be mentioned. In the case of the button type, a non-aqueous electrolyte battery can be produced by preparing a sheet-like positive electrode and negative electrode and sandwiching a separator between the positive electrode and the negative electrode. In the case of a spiral structure, for example, a non-aqueous electrolyte battery can be manufactured by preparing a sheet-like positive electrode, sandwiching a current collector, and stacking and winding a sheet-like negative electrode on the current collector. it can.

  Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples.

(Ionic liquid synthesis example 1)
A two-phase system consisting of 5 g of water and 5 g of chloroform was prepared, and the two-phase system was represented by 5 mL of triethylamine and the above general formula (III), where n was 3, and 1 of 6 R ³ 5 mL of a cyclic phosphazene compound, one of which is chlorine and five of which is fluorine, was successively added dropwise. When the two-phase system was stirred with a stirrer, an exotherm was observed with the reaction. After stirring for 3 minutes, the aqueous phase was collected and the water was evaporated to form white crystals, which were further dried under reduced pressure to obtain 5.2 g of white crystals (yield 53%). Next, 2 g of the obtained white crystals and 2.2 g of AgBF ₄ were dissolved in 20 mL of water, and after stirring for 30 minutes, the aqueous phase was collected and evaporated to leave a transparent liquid, which was further dried under reduced pressure. As a result, 1.8 g (yield 79%) of ionic liquid A was obtained. When the obtained ionic liquid A was dissolved in heavy water and analyzed by ¹ H-NMR, ³¹ P-NMR and ¹⁹ F-NMR, the ionic liquid A was represented by the above general formula (I). N was 3, 5 out of 6 R ¹ were fluorine and 1 was —N ⁺ (CH ₂ CH ₂ ) ₃ BF ₄ ^— . The result of ¹ H-NMR of the product is shown in FIG. 1, the result of ³¹ P-NMR is shown in FIG. 2, the result of ¹⁹ F-NMR is shown in FIG. 3, and the reaction scheme is shown below.

(Ionic liquid synthesis example 2)
A two-phase system consisting of 5 g of water and 5 g of chloroform was prepared, and the two-phase system was represented by 5 mL of N-methyl-2-pyrrolidone and the above general formula (III), where n was 3, 5 mL of a cyclic phosphazene compound in which one of the three R ^{3 s} is chlorine and five are fluorine was successively added dropwise. When the two-phase system was stirred with a stirrer, an exotherm was observed with the reaction. After stirring for 3 minutes, the aqueous phase was collected and the water was evaporated to form white crystals, which were further dried under reduced pressure to obtain 3.6 g of white crystals (yield 35.7%). Next, 2 g of the obtained white crystals and 2.3 g of AgBF ₄ were dissolved in 20 mL of water, and after stirring for 30 minutes, the aqueous phase was collected and evaporated to leave a transparent liquid, which was further dried under reduced pressure. As a result, 1.21 g (yield 53.3%) of ionic liquid B was obtained. When the obtained ionic liquid B was dissolved in heavy water and analyzed by ¹ H-NMR, the ionic liquid B was represented by the above general formula (I), where n was 3, Five of R ¹ are fluorine and one is an ionic substituent represented by the above general formula (II), X ⁻ in formula (II) is BF ₄ ⁻ , and one of R ² is a methyl group, It was confirmed that the other two R ² were bonded to each other to form a 2-azacyclopentanone ring together with the nitrogen atom. The result of ¹ H-NMR of the product is shown in FIG. 4, the result of ³¹ P-NMR is shown in FIG. 5, and the reaction scheme is shown below.

(Ionic liquid synthesis example 3)
A two-phase system consisting of 15 mL of water and 15 mL of chloroform was prepared, and the two-phase system was represented by 5 mL of pyridine and the above general formula (III), where n was 3 and 1 of 6 R ³ 5 mL of a cyclic phosphazene compound, one of which is chlorine and five of which is fluorine, was successively added dropwise. Thereafter, when the two-phase system was stirred while cooling, white crystals were precipitated in the chloroform phase. When the mixture was returned to room temperature and stirred, the white crystals disappeared. The chloroform phase was colorless before the reaction, but became cloudy after the reaction. The aqueous phase was collected using a pipette and evaporated, and then water was distilled off using a vacuum pump to obtain 5.2 g (yield 57%) of white crystals. Next, 2 g of the obtained white crystals and 2.3 g of AgBF ₄ were dissolved in 20 mL of water, and after stirring for 30 minutes, the aqueous phase was collected and evaporated to leave a transparent liquid, which was further dried under reduced pressure. As a result, 1.4 g (yield 60%) of ionic liquid C was obtained. The obtained ionic liquid C was dissolved in heavy water and analyzed by ¹ H-NMR. As a result, the ionic liquid C was represented by the general formula (I), where n was 3, It was confirmed that five of R ¹ were fluorine and one was —N ⁺ C ₅ H ₅ BF ₄ ^— . The result of ¹ H-NMR of the product is shown in FIG. 6, the result of ³¹ P-NMR is shown in FIG. 7, and the reaction scheme is shown below.

(Ionic liquid synthesis example 4)
A two-phase system consisting of 15 mL of water and 15 mL of chloroform was prepared, and the two-phase system was represented by 5 mL of aniline and the above general formula (III), where n was 3, and 1 of 6 R ³ 5 mL of a cyclic phosphazene compound, one of which is chlorine and five of which is fluorine, was successively added dropwise. Thereafter, when the two-phase system was stirred while cooling, white crystals were precipitated in the chloroform phase. When the mixture was returned to room temperature and stirred, the white crystals disappeared. The chloroform phase was colorless before the reaction, but became cloudy after the reaction. The aqueous phase was collected using a pipette and evaporated, and then water was distilled off using a vacuum pump to obtain 4.8 g of white crystals (yield 54%). Next, 2 g of the obtained white crystals and 2.3 g of AgBF ₄ were dissolved in 20 mL of water, and after stirring for 30 minutes, the aqueous phase was collected and evaporated to leave a transparent liquid, which was further dried under reduced pressure. As a result, 1.6 g (yield 72%) of ionic liquid D was obtained. When the obtained ionic liquid D was dissolved in heavy water and analyzed by ¹ H-NMR, the ionic liquid D was represented by the above general formula (I), where n was 3, It was confirmed that five of R ¹ were fluorine and one was —N ⁺ H ₂ C ₆ H ₅ BF ₄ ^— . The result of ¹ H-NMR of the product is shown in FIG. 8, the result of ³¹ P-NMR is shown in FIG. 9, and the reaction scheme is shown below.

(Ionic liquid synthesis example 5)
The two-phase system consisting of water 15mL of chloroform 15mL prepared, and dimethylaniline 5mL in the two-phase system, represented by the general formula (III), a wherein n is 3, among the six R ³ 5 mL of a cyclic phosphazene compound, one of which is chlorine and five of which is fluorine, was successively added dropwise. Thereafter, when the two-phase system was stirred while cooling, white crystals were precipitated in the chloroform phase. When the mixture was returned to room temperature and stirred, the white crystals disappeared. The chloroform phase was colorless before the reaction, but became cloudy after the reaction. The aqueous phase was collected using a pipette and evaporated, and then water was distilled off using a vacuum pump to obtain 5.1 g of white crystals (yield 52%). Next, 2 g of the obtained white crystals and 2.3 g of AgBF ₄ were dissolved in 20 mL of water, and after stirring for 30 minutes, the aqueous phase was collected and evaporated to leave a transparent liquid, which was further dried under reduced pressure. As a result, 1.5 g (yield 65%) of ionic liquid E was obtained. When the obtained ionic liquid E was dissolved in heavy water and analyzed by ¹ H-NMR, the ionic liquid E was represented by the above general formula (I), where n was 3, It was confirmed that five of R ¹ were fluorine and one was —N ⁺ (CH ₃ ) ₂ C ₆ H ₅ BF ₄ ^— . The result of ¹ H-NMR of the product is shown in FIG. 10, the result of ³¹ P-NMR is shown in FIG. 11, and the reaction scheme is shown below.

(Ionic liquid synthesis example 6)
Triethylamine synthesized in the same manner as in the above ionic liquid synthesis example 1 and represented by the above general formula (III), wherein n is 3, 1 of 6 R ³ is chlorine and 5 are fluorine 1 g of LiCF ₃ SO ₃ is reacted with 2 g of the reaction product with the cyclic phosphazene compound, and 1 g of the reaction product is filtered, followed by filtration to obtain an ionic liquid F [represented by the above general formula (I), where n is 3 and 5 out of 6 R ¹ are fluorine and one is —N ⁺ (CH ₂ CH ₂ ) ₃ .CF ₃ SO ₃ ^— ], 1.54 g (yield 61%) was obtained. .

(Ionic liquid synthesis example 7)
An ionic liquid G was obtained in the same manner as in the ionic liquid synthesis example 1 except that AgPF ₆ was used instead of AgBF ₄ . The obtained ionic liquid G was analyzed by ¹ H-NMR, represented by the above general formula (I), wherein n is 3, 5 out of 6 R ¹ are fluorine and 1 is —N. ^{_{+ (CH 2 CH 2) 3}} PF 6 - was identified as those compounds.

(Ionic liquid synthesis example 8)
But using AgPF ₆ in place of AgBF ₄ in the same manner as the ion liquid Synthesis Example 4, to give the ionic liquid H. The obtained ionic liquid H is analyzed by ¹ H-NMR, represented by the above general formula (I), wherein n is 3, 5 of 6 R ¹ are fluorine and 1 is —N. ^{_{+ H 2 C 6 H 5 PF}} 6 - it was identified as those compounds.

(Ionic liquid synthesis example 9)
An ionic liquid I was obtained in the same manner as in the above ionic liquid synthesis example 5 except that AgPF ₆ was used instead of AgBF ₄ . The obtained ionic liquid I was analyzed by ¹ H-NMR, represented by the above general formula (I), wherein n is 3, 5 of 6 R ¹ are fluorine and 1 is —N. ^{_{+ (CH 3) 2 C 6}} H 5 PF 6 - it was identified as those compounds.

Example 1
LiPF ₆ (supporting salt) was dissolved to 1 mol / L (M) in the ionic liquid A synthesized as described above to prepare a nonaqueous electrolytic solution. The safety of the obtained nonaqueous electrolytic solution was evaluated by the following method. The results are shown in Table 1.

(1) Electrolyte Safety The safety of the electrolyte was evaluated from the combustion behavior of flames ignited in an atmospheric environment by the method of arranging UL94HB method of UL (Underwriting Laboratory) standard. At that time, ignitability, combustibility, formation of carbides, and secondary ignition phenomena were also observed. Specifically, based on the UL test standard, a nonflammable quartz fiber was impregnated with 1.0 mL of an electrolytic solution, and a test piece of 127 mm × 12.7 mm was produced. Here, when the test flame does not ignite the test piece (combustion length: 0 mm), it is “non-flammable”, and when the ignited flame does not reach the 25 mm line and the fallen object is not ignited, “flame retardant” The case where the ignited flame was extinguished on the 25 to 100 mm line and the fallen object was not ignited was evaluated as “self-extinguishing”, and the case where the ignited flame exceeded the 100 mm line was evaluated as “combustible”.

<Production of lithium secondary battery>
Next, lithium cobalt composite oxide (LiCoO ₂ ) or lithium manganese composite oxide (LiMn ₂ O ₄ ) is used as the positive electrode active material, and the composite oxide, acetylene black as a conductive agent, and a binder are used. After mixing a certain fluororesin with a mass ratio of 90: 5: 5, dispersing this in N-methylpyrrolidone and applying it to an aluminum foil as a positive electrode current collector, and drying it, φ16mm This was punched into a disc shape to produce a positive electrode. On the other hand, the negative electrode was a lithium foil (thickness 0.5 mm) punched out to φ16 mm. Next, the positive electrode and the negative electrode are stacked and accommodated in a stainless steel case that also serves as a positive electrode terminal via a separator (microporous film: made of polypropylene) impregnated with an electrolytic solution, and the negative electrode terminal is inserted through a polypropylene gasket. It was sealed with a stainless steel sealing plate that also serves as a CR2016 type coin-type battery (lithium secondary battery) having a capacity of 4 mAh. The initial discharge capacity of the obtained battery and the discharge capacity after 10 cycles were measured by the following method, and the results shown in Table 1 were obtained.

(2) Discharge capacity at the initial stage and after 10 cycles
Under an environment of 20 ° C, charge and discharge are performed under the conditions of an upper limit voltage of 4.2 V, a lower limit voltage of 3.0 V, a discharge current of 50 mA, and a charge current of 50 mA, and the initial discharge capacity is obtained by dividing the discharge capacity at this time by the known electrode weight. (MAh / g) was determined. Furthermore, charge / discharge was repeated up to 10 cycles under the same charge / discharge conditions, and the discharge capacity after 10 cycles was determined.

(Examples 2 to 6)
LiPF ₆ (supporting salt) was dissolved in the ionic liquids B to F synthesized as described above so as to be 1 mol / L (M) to prepare a nonaqueous electrolytic solution. The safety of the obtained nonaqueous electrolytic solution was evaluated by the above method. Further, using the non-aqueous electrolyte, a lithium secondary battery was produced in the same manner as in Example 1, and the discharge capacity at the initial stage and after 10 cycles was measured. The results are shown in Table 1.

(Comparative Example 1)
LiPF ₆ was dissolved in a mixed solvent composed of 50% by volume of ethylene carbonate (EC) and 50% by volume of diethyl carbonate (DEC) so as to be 1 mol / L to prepare a nonaqueous electrolytic solution. The safety of the obtained nonaqueous electrolytic solution was evaluated by the above method. Further, using the non-aqueous electrolyte, a lithium secondary battery was produced in the same manner as in Example 1, and the discharge capacity at the initial stage and after 10 cycles was measured. The results are shown in Table 1.

As apparent from Table 1, electrolytic solution comprising an ionic liquid and a support salt represented by unrealized and Formula phosphorus and nitrogen in the cation moiety (I) are safety is very high, further, electrolytic It turns out that the cycling characteristics of a battery can be improved by using a liquid for a lithium secondary battery.

(Examples 7 to 16 and Comparative Example 2)
LiPF ₆ was dissolved in a solvent having the composition shown in Table 2 so as to be 1 mol / L to prepare a nonaqueous electrolytic solution. In Table 2, EC / PC / DMC represents a mixed organic solvent containing ethylene carbonate (EC), propylene carbonate (PC), and dimethyl carbonate (DMC) at a volume ratio of 1/3. The safety of the obtained nonaqueous electrolytic solution was evaluated by the above method. Further, using the non-aqueous electrolyte, a lithium secondary battery was produced in the same manner as in Example 1, and the discharge capacity at the initial stage and after 20 cycles was measured. The results are shown in Table 2.

  From Table 2, it can be seen that when an aprotic organic solvent is contained, the safety of the electrolytic solution becomes very high when the content of the ionic liquid is 5% by volume or more.

(Example 17)
LiBF ₄ (supporting salt) was dissolved to 1 mol / L (M) in the ionic liquid A synthesized as described above to prepare a nonaqueous electrolytic solution. The safety of the obtained nonaqueous electrolytic solution was evaluated by the above method. The results are shown in Table 3.

<Production of lithium primary battery>
MnO ₂ (positive electrode active material), acetylene black (conductive agent), and polyvinylidene fluoride (binder) were mixed and kneaded at a ratio (mass ratio) of 8: 1: 1, and the kneaded product was doctored. After coating with a blade, what was obtained by hot-air drying (100 to 120 ° C.) was cut out with a φ16 mm punch to produce a positive electrode. The mass of the positive electrode is 20 mg. The negative electrode was a lithium foil (thickness 0.5 mm) punched out to φ16 mm, and the current collector was nickel foil. The positive and negative electrodes were placed facing each other through a cellulose separator [TF4030 manufactured by Nippon Kogyo Paper Industries Co., Ltd.], the electrolyte was injected and sealed, and a CR2016 type lithium primary battery (nonaqueous electrolyte primary battery) was produced. . The obtained battery was discharged at 0.2 C at a lower limit voltage of 1.5 V in an environment of 25 ° C., and the discharge capacity was measured. Further, the battery produced in the same manner as described above was stored at 120 ° C. for 60 hours, and the room temperature discharge capacity after storage was measured in the same manner as described above. Further, the room temperature discharge capacity after storage at 120 ° C. for 60 hours was divided by the room temperature discharge capacity immediately after production to calculate the discharge capacity remaining rate after storage at high temperature. The results are shown in Table 2.

(Examples 18 to 21)
LiBF ₄ (supporting salt) was dissolved to 1 mol / L (M) in the ionic liquids B to E synthesized as described above to prepare a nonaqueous electrolytic solution. The safety of the obtained nonaqueous electrolytic solution was evaluated by the above method. Further, using the non-aqueous electrolyte, a lithium primary battery was produced in the same manner as in Example 17, the discharge capacity immediately after production and after storage at high temperature was measured, and the discharge capacity remaining rate after storage at high temperature was further calculated. . The results are shown in Table 3.

(Comparative Example 3)
A nonaqueous electrolytic solution was prepared by dissolving LiBF _{4 in a} mixed solvent consisting of 50% by volume of propylene carbonate (PC) and 50% by volume of 1,2-dimethoxyethane (DME) to 1 mol / L. The safety of the obtained nonaqueous electrolytic solution was evaluated by the above method. Further, using the non-aqueous electrolyte, a lithium primary battery was produced in the same manner as in Example 17, the discharge capacity immediately after production and after storage at high temperature was measured, and the discharge capacity remaining rate after storage at high temperature was further calculated. . The results are shown in Table 3.

As apparent from Table 3, the electrolytic solution comprising an ionic liquid and a supporting salt represented by unrealized and Formula phosphorus and nitrogen in the cation moiety (I) are safety is very high, further, electrolytic It can be seen that by using the liquid in a lithium primary battery, the room temperature discharge capacity of the battery after high temperature storage is improved and the high temperature storage characteristics of the battery can be improved.

It is the result of ¹ H-NMR of the product obtained in the ionic liquid synthesis example 1. It is a ³¹ P-NMR result of the product obtained in the ionic liquid synthesis example 1. It is a ¹⁹ F-NMR result of the product obtained in the ionic liquid synthesis example 1. It is the result of ¹ H-NMR of the product obtained in the ionic liquid synthesis example 2. It is a ³¹ P-NMR result of the product obtained in the ionic liquid synthesis example 2. It is a ¹ H-NMR result of the product obtained in the ionic liquid synthesis example 3. It is a ³¹ P-NMR result of the product obtained in the ionic liquid synthesis example 3. It is the result of ¹ H-NMR of the product obtained in the ionic liquid synthesis example 4. It is a ³¹ P-NMR result of the product obtained in the ionic liquid synthesis example 4. It is a ¹ H-NMR result of the product obtained in the ionic liquid synthesis example 5. It is a ³¹ P-NMR result of the product obtained in the ionic liquid synthesis example 5.

Claims (6)

In a non-aqueous electrolyte for a battery containing an ionic liquid composed of a cation part and an anion part, and a supporting salt,
The cation portion of the ionic liquid contains phosphorus and nitrogen,
The ionic liquid has the following general formula (I):
(NPR ¹ ₂ ) _n ... (I)
[Wherein R ¹ is independently a halogen element or a monovalent substituent, and at least one R ¹ is represented by the following general formula (II):
_{^{-N + R 2 3 X - ···}} (II)
Wherein R ² is each independently a monovalent substituent or hydrogen, provided that at least one R ² is not hydrogen and R ² may be bonded to each other to form a ring; X ^- is be ionic substituent represented by represents a monovalent anion); n is a non-aqueous electrolyte battery characterized by being represented by a 3].   The non-aqueous electrolyte for a battery according to claim 1, comprising only the ionic liquid and a supporting salt.   Furthermore, the non-aqueous electrolyte for batteries of Claim 1 containing an aprotic organic solvent.   The non-aqueous electrolyte for a battery according to claim 3, containing 5% by volume or more of the ionic liquid. 2. The non-battery according to claim 1, wherein at least one R ¹ in the general formula (I) is an ionic substituent represented by the general formula (II) and the other is fluorine. Water electrolyte. A nonaqueous electrolyte battery comprising the battery nonaqueous electrolyte solution according to claim 1 , a positive electrode, and a negative electrode.

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