TW202123523A - A thermal runaway inhibitor - Google Patents

Abstract

The present invention provides: a thermal runaway inhibitor comprising a phosphate ester compound represented by general formula (1) described in the description, the thermal runaway being caused by an internal short-circuit of a non-aqueous electrolyte secondary battery; and a method for inhibiting a thermal runaway caused by an internal short-circuit of a non-aqueous electrolyte power storage device by including 0.01-10 mass% of said thermal runaway inhibitor in a non-aqueous electrolyte.

Description

Thermal runaway inhibitor

The present invention relates to a thermal runaway inhibitor caused by an internal short circuit of a non-aqueous electrolyte power storage device and a method for suppressing the thermal runaway caused by the internal short circuit using the inhibitor.

Non-aqueous electrolyte secondary batteries such as lithium ion secondary batteries are widely used as portable computers, handheld cameras, information terminal devices, etc. due to their small size, light weight, high energy density, high capacity, and repetitive charging and discharging. Carry the power supply of electronic equipment. In addition, from the viewpoint of environmental issues, electric vehicles using non-aqueous electrolyte secondary batteries or hybrid vehicles using electric power as part of the power are being put into practical use.

The non-aqueous electrolyte secondary battery is composed of components such as electrodes, separators, and non-aqueous electrolytes. The main solvent of the non-aqueous electrolyte uses a flammable organic solvent. When high energy is released due to an internal short circuit, thermal runaway may occur, and there may be a risk of fire or rupture. Therefore, various countermeasures have been proposed for review. Such a countermeasure is known as a method of using a porous film whose main component is polyolefin as a separator (see, for example, Patent Documents 1 and 2); in addition to the separator, a porous heat-resistant layer is provided between the positive electrode and the negative electrode. Method (see, for example, Patent Document 3); method of coating the surface of an electrode active material with a metal oxide (see, for example, Patent Document 4); method of using lithium-containing nickel oxide as a positive electrode active material (see, for example, Patent Document 5) Method of using an olivine-type lithium phosphate compound as a positive electrode active material (see, for example, Patent Document 6); using a spinel-structured lithium titanate compound as a method of negative electrode active material (see, for example, Patent Document 7); using non-flammable The method of using a fluorine-based solvent as the main solvent of the non-aqueous electrolyte (see, for example, Patent Documents 8 and 9); the method of using a solid electrolyte instead of using an organic solvent as the non-aqueous electrolyte (see, for example, Patent Document 10), and the like.

In order to prevent internal short-circuits with the porous film separator whose main component is polyolefin, it is necessary to thicken the separator. In the method of providing the porous heat-resistant layer, the battery becomes larger due to the porous heat-resistant layer. In the method of coating the surface of the electrode active material with a metal oxide, the content of the electrode active material contained in the electrode mixture layer of the electrode will be relatively reduced, and the capacity of the battery will be reduced. The capacity of these non-aqueous electrolyte secondary batteries has advantages. In the method of using lithium-containing nickel oxide or olivine-type lithium phosphate compound as the positive electrode active material, or the method of using the spinel-structured lithium titanate compound as the negative electrode active material, high energy density cannot be obtained either. In addition, in the method of using a fluorine-based solvent, since the fluorine-based solvent is very expensive and needs to be used in large quantities, this leads to a significant increase in cost. In the method of using a solid electrolyte, since a solid electrolyte material having no fluidity is used, the internal resistance becomes high, and the performance is lowered compared with a non-aqueous electrolyte using an organic solvent.

On the other hand, phosphate compounds are known as flame retardants, and lithium ion secondary batteries having non-aqueous electrolytes containing phosphate compounds are also known. However, although alkyl phosphate compounds have the effect of improving flame retardancy, the effect of suppressing thermal runaway caused by internal short-circuits is insufficient (see, for example, Patent Documents 11 to 13). Aromatic phosphate compounds are known to inhibit thermal runaway during overcharging. (See, for example, Patent Document 14), however, the effect of suppressing thermal runaway caused by internal short circuits is still unknown. [Prior Technical Literature] [Patent Literature]

Patent Document 1: International Publication No. 2016/152266 Patent Document 2: International Publication No. 2016/056288 Patent Document 3: Japanese Patent Application Publication No. 2005-174792 Patent Document 4: Japanese Patent Application Publication No. 2011-216300 Patent Document 5: Japanese Patent Laid-Open No. 2002-015736 Patent Document 6: Japanese Patent Application Publication No. 2007-012441 Patent Document 7: Japanese Patent Laid-Open No. 2008-159280 Patent Document 8: International Publication No. 2007/043526 Patent Document 9: International Publication No. 2008/007734 Patent Document 10: Japanese Patent Application Laid-Open No. 2016-207567 Patent Document 11: Japanese Patent Laid-Open No. 11-176471 Patent Document 12: Japanese Patent Application Laid-Open No. 2008-204789 Patent Document 13: Japanese Patent Application Publication No. 2015-065130 Patent Document 14: Japanese Patent Laid-Open No. 2005-347240

[The problem to be solved by the invention]

The subject of the present invention is to provide an additive for manufacturing a non-aqueous electrolyte power storage device that does not increase in size or greatly increase the cost, does not easily cause thermal runaway even if an internal short circuit occurs, and has a low risk of fire or rupture. [Means used to solve the problem]

The inventors of the present invention studied and reviewed the above-mentioned problems and found that even a non-aqueous electrolyte power storage device having a non-aqueous electrolyte using an organic solvent as a solvent, by blending a phosphoric acid aromatic ester compound in the non-aqueous electrolyte, thermal runaway is unlikely to occur. , It can prevent internal short circuit from causing fire or rupture, thus completing the present invention. That is, the present invention is a thermal runaway inhibitor, which is a thermal runaway inhibitor for a non-aqueous electrolyte power storage device containing a phosphate compound represented by the following general formula (1), and the aforementioned non-aqueous electrolyte power storage device has: In the positive electrode of the positive electrode active material, the negative electrode containing the negative electrode active material, and the non-aqueous electrolyte, the aforementioned thermal runaway is a thermal runaway caused by an internal short circuit of the non-aqueous electrolyte power storage device.

(In the formula, R ¹ to R ⁴ are independent of each other and represent a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 4 carbon atoms, X ¹ represents a group represented by general formula (2) or general formula (3), and a represents 0 Or a number from 1 to 4).

(In the formula, R ⁵ to R ⁸ are independent of each other and represent a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 4 carbon atoms, and X ² represents a direct bond, an oxygen atom, a sulfur atom, a sulfinyl group, a sulfinyl group, Or the base represented by the following general formula (4), b represents the number of 0 or 1, and * represents a bonding bond).

(In the formula, R ⁹ to R ¹⁰ are independent of each other and represent a hydrogen atom, a hydrocarbon group with 1 to 10 carbons, a fluorinated alkyl group with 1 to 2 carbons, or a ^{cross-linked R 9} and R ¹⁰ with a carbon number of 5 to The hydrocarbon group of 12, * represents a bonding bond).

(In the formula, R ¹¹ to R ¹⁴ are independent of each other and represent a hydrogen atom, a fluorine atom, a hydrocarbon group with 1 to 10 carbons, and a fluorinated alkyl group with 1 to 2 carbons, and * represents a bonding bond). [Effects of Invention]

By using the thermal runaway inhibitor obtained by the present invention, it is possible to provide a small size, light weight, high capacity, and low risk of thermal runaway, fire or rupture, even if an internal short circuit occurs, without increasing the size or greatly increasing the cost. The non-aqueous electrolyte storage device.

The present invention is a thermal runaway inhibitor for a non-aqueous electrolyte power storage device, which is characterized by containing a phosphate compound represented by general formula (1). Furthermore, the non-aqueous electrolyte power storage device has a positive electrode containing a positive electrode active material, a negative electrode containing the negative electrode active material, and a non-aqueous electrolyte, and the thermal runaway is a thermal runaway caused by an internal short circuit of the non-aqueous electrolyte power storage device. In addition, the phosphoric acid ester compound represented by the general formula (1) may be referred to as the phosphoric acid ester compound of the present invention.

In general formula (1), R ¹ to R ⁴ are each independent and represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. The alkyl group having 1 to 4 carbon atoms includes a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a secondary butyl group, and a tertiary butyl group. R ¹ to R ^{4 are} preferably a hydrogen atom, a methyl group, and an ethyl group, more preferably a hydrogen atom and a methyl group, and most preferably a hydrogen atom, from the viewpoint of the large effect of suppressing thermal runaway.

X ¹ represents a group represented by the following general formula (2) or general formula (3).

(In the formula, R ⁵ to R ⁸ are independent of each other and represent a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 4 carbon atoms, and X ² represents a direct bond, an oxygen atom, a sulfur atom, a sulfinyl group, a sulfinyl group, Or the base represented by the following general formula (4), b represents the number of 0 or 1, and * represents a bonding bond).

(In the formula, R ⁹ to R ¹⁰ are independent of each other and represent a hydrogen atom, a hydrocarbon group with 1 to 10 carbons, a fluorinated alkyl group with 1 to 2 carbons, or a ^{cross-linked R 9} and R ¹⁰ with a carbon number of 5 to The hydrocarbon group of 12, * represents a bonding bond).

(In the formula, R ¹¹ to R ¹⁴ are independent of each other and represent a hydrogen atom, a fluorine atom, a hydrocarbon group with 1 to 10 carbons, a fluorinated alkyl group with 1 to 2 carbons, and * represents a bonding bond)

In general formula (2), R ⁵ to R ⁸ are each independent and represent a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. The alkyl group having 1 to 4 carbon atoms includes the alkyl groups exemplified by R ¹ to R ^{4 in} the general formula (1). From the standpoint of the effect of suppressing thermal runaway, R ⁵ to R ^{8 are} preferably a hydrogen atom, a methyl group, and an ethyl group, more preferably a hydrogen atom and a methyl group, and most preferably a hydrogen atom.

X ² represents a direct bond, an oxygen atom, a sulfur atom, a sulfinyl group, a sulfonyl group, or the group represented by the aforementioned general formula (4), b represents the number of 0 or 1, and * represents a bonding bond.

In the general formula (4), R ⁹ and R ¹⁰ are independent of each other and represent a hydrogen atom, a fluorine atom, a hydrocarbon group with 1 to 10 carbons, a fluorinated alkyl group with 1 to 2 carbons, or R ⁹ and R ^{10 are} cross-linked It is a hydrocarbon group with 5-12 carbons. The hydrocarbon groups with 1 to 10 carbons include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, secondary butyl, tertiary butyl, pentyl, isopentyl, and secondary pentyl. , Third pentyl, hexyl, secondary hexyl, heptyl, octyl, 2-methylhexyl, 2-ethylhexyl, nonyl, decyl, cyclohexyl, phenyl, benzyl, cyclohexyl, cyclopentyl Base, 2-nor campanyl and so on. Examples of the fluoroalkyl group having 1 to 2 carbon atoms include fluoromethyl, difluoromethyl, trifluoromethyl, 2-fluoroethyl, 1,1,2,2-tetrafluoroethyl, and perfluoroethyl. The hydrocarbyl group formed by cross-linking R ⁹ and R ^{10 includes making X 2} a cyclohexylene group [the following formula (5)], 3,3,5-trimethylcyclohexylene [the following formula (6)], and Hydrocarbon group of hydrogen-4,7-methylene-5H-inden-5-ylidene [the following formula (7)] and 9H-fluorene-9-ylidene [the following formula (8)].

(Among formulas (5) to (8), * represents a bonding bond).

In general formula (3), R ¹¹ to R ¹⁴ are each independent and represent a hydrogen atom, a fluorine atom, a hydrocarbon group with 1 to 10 carbons, and a fluorinated alkyl group with 1 to 2 carbons, and * represents a bonding bond. The hydrocarbon group having 1 to 10 carbon atoms and the fluorinated alkyl group having 1 to 2 carbon atoms include the hydrocarbon groups and fluorinated alkylalkyl groups exemplified in the general formula (2). R ¹¹ to R ^{14 are} preferably a hydrogen atom, a methyl group, and an ethyl group, more preferably a hydrogen atom and a methyl group, and most preferably a hydrogen atom, from the viewpoint that the effect of suppressing thermal runaway is large.

X ^{2 is} preferably a group represented by a direct bond, an oxygen atom, a sulfonyl group, and general formula (4) from the viewpoint of a large effect of suppressing thermal runaway. In the case where X ² is not the group represented by the general formula (4), direct bonding or oxygen atom is more preferable, and direct bonding is even more preferable. When X ² is a group represented by general formula (4), R ⁹ and R ^{10 are} preferably a hydrogen atom, a methyl group, or an ethyl group, and a methyl group is more preferable.

In general formula (1), a represents 0 or a number from 1 to 4. When a is a number of 1 to 4, it may be a mixture of compounds having different repeating unit numbers a, and in the case of a mixture, a represents an average number. A is preferably a number of 1 to 4, preferably a number of 1 to 2, preferably a number of 1.0 to 1.7, and more preferably a number of 1.1 to 1.6.

Among the phosphoric acid ester compounds of the present invention, suitable compounds can be exemplified by the following formulas (9) to (17).

(Among formulas (9)～(17), a is synonymous with a in general formula (1))

Among the above-mentioned compounds, compounds represented by formula (9), formula (10), formula (11), formula (12) and formula (16) are preferred.

為佳，且以a為1.2的化合物為佳。The compound represented by formula (11) is

It is preferred, and a compound having a of 1.2 is preferred.

The compound represented by formula (12) is preferably a compound whose a is 1.2. The compound represented by formula (16) is preferably a compound whose a is 1.2.

The phosphate compound represented by the above general formula (1) can be obtained by a known method. For example, the compound in which a is 0 in the general formula (1) can be obtained by reacting phosphorus oxychloride with a compound having a hydroxyl group on the benzene ring, such as phenol and cresol under predetermined conditions. In addition, in the general formula (1), the compound whose a is 1 to 4 can also be combined with an excess of phosphorus oxychloride and a compound having two hydroxyl groups on the benzene ring, such as hydroquinone, resorcinol, and bisphenol After phenol A, biphenol F, etc. are reacted under predetermined conditions, unreacted phosphorus oxychloride is removed, and it is obtained by further reacting with a compound having a hydroxyl group on the benzene ring. In addition, the compound of general formula (1) where a is 1 to 4 can be obtained by reacting the compound of general formula (1) where a is 0 with a compound having two hydroxyl groups on the benzene ring. The resulting compound with a hydroxyl group on the benzene ring is removed by the so-called transesterification reaction.

In the present invention, the phosphate compound of the present invention is blended into a non-aqueous electrolyte as a thermal runaway inhibitor. The content of the phosphate compound of the present invention in the non-aqueous electrolyte is preferably 0.01% to 10% by mass, more preferably 0.05% to 5% by mass, and more preferably 0.1% to 3% by mass relative to the total amount of the non-aqueous electrolyte. % Is the best. When the content of the phosphate compound of the present invention in the non-aqueous electrolyte is too small, a sufficient thermal runaway suppression effect cannot be obtained, and when there are too many cases, an effect corresponding to an increase in the blending amount cannot be obtained. The phosphoric acid ester compound of the present invention may be used in one kind or in combination of two or more kinds. In the case of using two or more in combination, at least one compound in which a is 0 in general formula (1) and a compound in which a is 1 to 4 in general formula (1) is preferred.

The mechanism of the phosphate compound of the present invention to suppress thermal runaway caused by the internal short circuit of the non-aqueous electrolyte storage device has not been fully elucidated. It is presumed that in the initial stage of the internal short circuit, part of the phosphate compound of the present invention may be short-circuited. The current is decomposed, and an insulating film is formed on the surface of the electrode. This insulating film may also be formed of alkyl phosphate, but this is not sufficient. It is presumed that the phosphate compound of the present invention is especially in the case of compounds of formulas (9) to (17) with short alkyl groups or no alkyl groups. , Will form a strong insulating film.

In addition, the thermal runaway caused by the internal short circuit is the short circuit of the positive and negative electrodes. The electrons flow from the positive electrode to the negative electrode at a stretch, causing abnormal Joule heating. This heating will trigger the reaction between the electrolyte and the electrode, the thermal decomposition of the electrolyte, and the positive electrode. Thermal decomposition, etc., and the phenomenon of thermal runaway occurs. On the other hand, thermal runaway caused by overcharge is due to overcharge, lithium ions are excessively extracted from the positive electrode, the crystal structure of the positive electrode material is destroyed, the stability of the positive electrode is reduced, and the internal resistance of the battery increases. , The oxidative decomposition of electrolyte, etc., and the phenomenon of thermal runaway occurs. Like this, thermal runaway caused by internal short circuit and thermal runaway caused by overcharge are caused by completely different phenomena.

Specific examples of power storage devices include non-aqueous electrolyte secondary batteries (lithium ion secondary batteries, etc.) and electric double layer capacitors (lithium ion capacitors, etc.). The non-aqueous electrolyte related to this embodiment is particularly effective in the use of lithium ion secondary batteries and lithium ion capacitors.

The non-aqueous electrolyte of the non-aqueous electrolyte storage device applicable to the present invention includes, for example, a liquid electrolyte obtained by dissolving a supporting electrolyte in an organic solvent; a polymer gel electrolyte in which a supporting electrolyte is dissolved in an organic solvent and gelled with a polymer ; It does not contain organic solvents and supports pure polymer electrolytes composed of electrolytes dispersed in polymers. In particular, non-aqueous electrolyte power storage devices with liquid electrolytes are prone to thermal runaway due to internal short circuits, and the risk of fire or explosion is high. Therefore, the thermal runaway inhibitor of the present invention is suitable for use in non-aqueous electrolyte power storage devices with liquid electrolytes. Non-aqueous electrolyte is preferred.

As the supporting electrolyte used for the liquid electrolyte and the polymer gel electrolyte, conventionally known supporting electrolytes can be used. The following describes the supporting electrolyte when the non-aqueous electrolyte storage device is a lithium ion secondary battery or a lithium ion capacitor, while the sodium ion secondary battery or sodium ion capacitor uses a support after replacing lithium atoms with sodium atoms. Electrolyte. The supporting electrolyte used in the liquid electrolyte and the polymer gel electrolyte includes LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiN(CF ₃ SO ₂ ) ₂ , LiN(C ₂ F ₅ SO ₂ ) ₂ , LiN (SO ₂ F) ₂ , LiC (CF ₃ SO ₂ ) ₃ , LiB (CF ₃ SO ₃ ) ₄ , LiB (C ₂ O ₄ ) ₂ , LiBF ₂ (C ₂ O ₄ ), LiSbF ₆ , LiSiF ₅ , LiSCN, LiClO ₄ , LiCl, LiF, LiBr, LiI, LiAlF ₄ , LiAlCl ₄ , LiPO ₂ F ₂ and derivatives thereof, etc., among these, to use selected from LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiN(CF ₃ SO ₂ ) ₂ , LiN(C ₂ F ₅ SO ₂ ) ₂ , LiN(SO ₂ F) ₂ , LiPO ₂ F ₂ and LiC(CF ₃ SO ₂ ) ₃ and One or more types of derivatives of LiCF ₃ SO ₃ and derivatives of LiC(CF ₃ SO ₂ ) _{3 are preferred.} The content of the supporting electrolyte in the liquid electrolyte and the polymer gel electrolyte is preferably 0.5 mol/L to 7 mol/L, preferably 0.8 mol/L to 1.8 mol/L.

The supporting electrolyte used in the pure polymer electrolyte includes, for example, LiN(CF ₃ SO ₂ ) ₂ , LiN(C ₂ F ₅ SO ₂ ) ₂ , LiN(SO ₂ F) ₂ , LiC(CF ₃ SO ₂ ) ₃ , LiB(CF ₃ SO ₃ ) ₄ , LiB(C ₂ O ₄ ) ₂ .

The organic solvent used in the present invention for preparing the liquid non-aqueous electrolyte may be one of organic solvents generally used in non-aqueous electrolytes, or a combination of two or more. Specifically, for example, saturated cyclic carbonate compounds, saturated cyclic ester compounds, arsenic compounds, arsenic compounds, amide compounds, saturated chain carbonate compounds, chain ether compounds, cyclic ether compounds, saturated chain Like ester compounds and so on.

Among the aforementioned organic solvents, saturated cyclic carbonate compounds, saturated cyclic ester compounds, arsenite compounds, arsenic compounds, and amide compounds have high specific permittivity and can achieve the effect of increasing the permittivity of the non-aqueous electrolyte. Therefore, it is suitable, especially a saturated cyclic carbonate compound. Examples of saturated cyclic carbonate compounds include ethylene carbonate, 1,2-propylene carbonate, 1,3-propylene carbonate, 1,2-butylene carbonate, and 1,3-butylene carbonate. , 1,1-Dimethylethylene carbonate, etc. Examples of the saturated cyclic ester compound include γ-butyrolactone, γ-valerolactone, γ-caprolactone, δ-caprolactone, and δ-caprolactone. Examples of the above-mentioned sulphurite compounds include dimethyl sulphurite, diethyl sulphurite, dipropyl sulphurite, diphenyl sulphurite, thiophene and the like. The aforementioned stubborn compound includes, for example, dimethyl stubborn, diethyl stubborn, dipropyl stubborn, diphenyl stubborn, cyclobutane (also known as tetramethylene stubborn), 3-methylcyclobutane, 3 ,4-Dimethylcyclobutene, 3,4-diphenylmethylcyclobutene, cyclobutene, 3-methylcyclobutene, 3-ethylcyclobutene, 3-bromomethyl Cyclobutene, etc., cyclobutene and tetramethylcyclobutene are preferred. Examples of the aforementioned amide compound include N-methylpyrrolidone, dimethylformamide, and dimethylacetamide.

Among the aforementioned organic solvents, saturated chain carbonate compounds, chain ether compounds, cyclic ether compounds, and saturated chain ester compounds can reduce the viscosity of the non-aqueous electrolyte, increase the mobility of electrolyte ions, etc., and increase the output density. A compound with excellent battery characteristics. In addition, due to the low viscosity, the performance of the non-aqueous electrolyte at low temperatures can be improved. From this point of view, saturated chain carbonate compounds are particularly preferred. Saturated chain carbonate compounds, for example, dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate, ethyl butyl carbonate, methyl tert-butyl carbonate, diisopropyl carbonate, the first Tributyl propyl carbonate and so on. The aforementioned chain ether compound or cyclic ether compound includes, for example, dimethoxyethane, ethoxymethoxyethane, diethoxyethane, tetrahydrofuran, dioxpentane, dioxane, 1, 2-bis(methoxycarbonyloxy)ethane, 1,2-bis(ethoxycarbonyloxy)ethane, 1,2-bis(ethoxycarbonyloxy)propane, ethylene glycol bis( Trifluoroethyl) ether, propylene glycol bis(trifluoroethyl) ether, ethylene glycol bis(trifluoromethyl) ether, diethylene glycol bis(trifluoroethyl) ether, etc., among these, dioxins Pentane is preferred.

The aforementioned saturated chain ester compound is preferably a monoester compound and a diester compound whose total carbon number in the molecule is 2-8. Specific compounds include, for example, methyl formate, ethyl formate, methyl acetate, and acetic acid. Ethyl acetate, propyl acetate, isobutyl acetate, butyl acetate, methyl propionate, ethyl propionate, methyl butyrate, methyl isobutyrate, trimethyl methyl acetate, trimethyl ethyl acetate, propylene Methyl diacid, ethyl malonate, methyl succinate, ethyl succinate, methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethylene glycol diacetate, propylene glycol Diacetate, etc., methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, isobutyl acetate, butyl acetate, methyl propionate and ethyl propionate are preferred.

In addition, as the organic solvent used in the preparation of the non-aqueous electrolyte, for example, acetonitrile, propionitrile, nitromethane or its derivatives, and various ionic liquids can be used.

The polymers used in the polymer gel electrolyte include polyethylene oxide, polypropylene oxide, polyvinyl chloride, polyacrylonitrile, polymethyl methacrylate, polyethylene, polyvinylidene fluoride, and polyhexafluoroethylene. Propylene and so on. Examples of polymers used in the pure polymer electrolyte include polyethylene oxide, polypropylene oxide, and polystyrene sulfonic acid. The blending ratio in the gel electrolyte and the method of recombination are not particularly limited, and the blending ratios and well-known recombination methods known in the art can be used.

The non-aqueous electrolyte may further contain other well-known additives such as an electrode coating film forming agent, an antioxidant, a flame retardant, and an overcharge preventing agent in order to further improve battery life and safety.

The positive electrode containing the positive electrode active material of the non-aqueous electrolyte power storage device to which the present invention is applicable is an electrode in which an electrode mixture layer containing the positive electrode active material is formed on the current collector. For example, it can be used to make the positive electrode active material, binder, and conductive The auxiliary material is coated with an organic solvent or cement paste on the current collector and dried to make a sheet-shaped electrode.

As the positive electrode active material of the positive electrode, a well-known positive electrode active material can be used. The following describes the supporting electrolyte when the non-aqueous electrolyte storage device is a lithium ion secondary battery or a lithium ion capacitor, and in the case of a sodium ion secondary battery or a sodium ion capacitor, the lithium atom is replaced by sodium atom Positive active material.

In the case of lithium ion secondary batteries or lithium ion capacitors, well-known positive electrode active materials include, for example, lithium transition metal composite oxides, lithium-containing transition metal phosphate compounds, lithium-containing silicate compounds, and lithium-containing transition metal sulfuric acid. Compounds, sulfur, sulfur-containing compounds, etc. The transition metal of the foregoing lithium transition metal composite oxide is preferably vanadium, titanium, chromium, manganese, iron, cobalt, nickel, copper, etc. Specific examples of lithium transition metal composite oxides include lithium cobalt composite oxides such as _{LiCoO 2 , lithium nickel composite oxides such as LiNiO 2} , and lithium manganese composite oxides such as LiMnO ₂ , LiMn ₂ O ₄ and Li ₂ MnO ₃ Some of the transition metal atoms in these lithium transition metal composite oxides as the main body are aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, lithium, nickel, copper, zinc, magnesium, gallium, zirconium and other metals Substituted compounds, etc. Examples of lithium transition metal composite oxides obtained by substituting a part of the main transition metal atoms with other metals include Li _1.1 Mn _1.8 Mg _0.1 O ₄ , Li _1.1 Mn _1.85 Al _0.05 O ₄ , and LiNi _0.5 Co _0.2 Mn _0.3 O _2. LiNi _0.8 Co _0.1 Mn _0.1 O ₂ , LiNi _0.5 Mn _0.5 O ₂ , LiNi _0.80 Co _0.17 Al _0.03 O ₂ , LiNi _0.80 Co _0.15 Al _0.05 O ₂ , Li(Ni _1/3 Co _1/3 Mn _1/3 ) O ₂ , LiNi _0.6 Co _0.2 Mn _0.2 O ₂ , LiMn _1.8 Al _0.2 O ₄ , LiNi _0.5 Mn _1.5 O ₄ , Li ₂ MnO ₃ -LiMO ₂ (M=Co, Ni, Mn), etc. The transition metal of the aforementioned lithium-containing transition metal phosphate compound is preferably vanadium, titanium, manganese, iron, cobalt, nickel, etc. Specific examples include LiFePO ₄ , LiMn _x Fe _1-x PO ₄ (0＜x＜1 ) And other iron phosphate compounds, LiCoPO ₄ and other cobalt phosphate compounds. In these lithium transition metal phosphate compounds, part of the transition metal atoms as the main body is aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, lithium, and nickel. , Copper, zinc, magnesium, gallium, zirconium, niobium and other metal substituted compounds, Li ₃ V ₂ (PO ₄ ) ₃ and other vanadium phosphate compounds. Examples of the lithium-containing silicate compound include Li ₂ FeSiO ₄ and the like. Examples of lithium-containing transition metal sulfuric acid compounds include LiFeSO ₄ and LiFeSO ₄ F. Only one kind of these may be used, or two or more kinds may be used in combination.

The thermal runaway inhibitor of the present invention is suitable for use in non-aqueous electrolyte power storage devices with high charge and discharge capacity. Positive electrode active materials with high charge and discharge capacity include LiCoO ₂ , LiMn ₂ O ₄ , LiNi _0.5 Mn _1.5 O ₄ , Li(Ni _0.8 Co _0.15 Al _0.05 )O ₂ , LiNi _X Co _Y Mn _Z O ₂ (X+ Y+Z=1, 0≦X≦1, 0≦Y≦1, 0≦Z≦1), LiNiO ₂ , Li ₂ MnO ₃ -LiMO ₂ (M=Co, Ni, Mn), thermal runaway of the present invention The inhibitor is suitable for use in non-aqueous electrolyte power storage devices having these positive electrode active materials.

The binder can include, for example, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), ethylene-propylene-diene copolymer (EPDM), styrene-butadiene rubber (SBR), acrylonitrile butadiene Rubber (NBR), styrene-isoprene copolymer, polymethacrylate, polyacrylate, polyvinyl alcohol (PVA), carboxymethyl cellulose (CMC), sodium carboxymethyl cellulose ( CMCNa), methyl cellulose (MC), starch, polyvinylpyrrolidone, polyethylene (PE), polypropylene (PP), polyethylene oxide (PEO), polyimide (PI), polyamide Amide (PAI), polyacrylonitrile (PAN), polyvinyl chloride (PVC), polyacrylic acid, polyurethane, etc. The amount of the binder used is usually about 1% by mass to 20% by mass relative to the positive electrode active material, preferably 2% by mass to 10% by mass.

Conductive auxiliary materials, for example, carbon black, Ketjen black, acetylene black, channel black, furnace black, lamp black, thermal carbon black, carbon nanotubes, vapor-phase carbon fiber (Vapor Grown Carbon Fiber; VGCF), graphene Carbon materials such as, fullerenes, needle-like coal char; metal powders such as aluminum powder, nickel powder, and titanium powder; conductive metal oxides such as zinc oxide and titanium oxide; La ₂ S ₃ , Sm ₂ S ₃ , Sulfides such as Ce ₂ S ₃ and TiS _2. The particle size of the conductive auxiliary agent preferably has an average particle size of 0.0001 μm to 100 μm, preferably 0.01 μm to 50 μm.

As the slurrying solvent, an organic solvent or water that can dissolve the binder can be used. Organic solvents include, for example, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethylenetriamine, N , N-Dimethylaminopropylamine, ethylene oxide, tetrahydrofuran, etc. The amount of the solvent used is usually about 10% by mass to 400% by mass, preferably 20% by mass to 200% by mass relative to the positive electrode active material.

As the current collector of the positive electrode, aluminum, stainless steel, nickel-plated steel, or the like can usually be used. The shape of the current collector may be a foil shape, a plate shape, a mesh shape, etc., and a foil shape is preferred. In the case of a foil shape, the thickness of the foil is usually 1 μm to 100 μm.

The negative electrode containing the negative electrode active material of the non-aqueous electrolyte power storage device to which the present invention is applicable is an electrode in which an electrode mixture layer containing the negative electrode active material is formed on the current collector. For example, the negative electrode active material, binder, and conductive auxiliary material can be used. The object made by organic solvent or cement slurry is coated on the current collector and dried to make a sheet-shaped electrode.

As the negative electrode active material of the negative electrode, a well-known negative electrode active material can be used. The following is a description of the supporting electrolyte when the non-aqueous electrolyte storage device is a lithium ion secondary battery or a lithium ion capacitor. In the case of a sodium ion secondary battery or a sodium ion capacitor, lithium atoms are used in the negative electrode active material. A negative electrode active material in which the lithium atoms of the negative electrode active material are replaced with sodium atoms.

Known negative electrode active materials include carbonaceous materials, lithium, lithium alloys, silicon, silicon alloys, silicon oxide, tin, tin alloys, tin oxide, phosphorus, germanium, indium, copper oxide, antimony sulfide, titanium oxide, and iron oxide , Manganese oxide, cobalt oxide, nickel oxide, lead oxide, ruthenium oxide, tungsten oxide, zinc oxide, in addition to composite _{oxides such as LiVO 2} , Li ₂ VO ₄ , Li ₄ Ti ₅ O ₁₂ , and titanium-niobium-based oxides , Conductive polymers, sulfur-containing compounds, etc. The carbonaceous material is not particularly limited, and examples include crystals of natural graphite, artificial graphite, fullerene, graphene, short graphite fibers, carbon nanotubes, graphite whiskers, high-alignment thermally decomposed graphite, and condensed graphite. Carbon, hardly graphitized carbon, easily graphitized carbon, petroleum-based coal coke, coal-based coal coke, petroleum-based pitch carbide, coal-based pitch carbide, phenol resin, crystalline cellulose and other resin carbides, etc. Carbon materials, furnace black, acetylene black, pitch-based carbon fibers, polyacrylonitrile-based carbon fibers, etc., which are partially carbonized of these substances. Examples of the sulfur-containing compound include sulfur-modified polyacrylonitrile, polysulfide carbon represented by the general formula (CSx)n (x is 0.9 to 1.5 and n is a number of 4 or more). In addition, when the positive electrode active material is a sulfur-containing compound, a negative electrode active material other than the sulfur-containing compound may be used as the negative electrode active material.

Examples of binders, conductive aids, and slurried solvents are the same as in the case of the positive electrode. The amount of the above-mentioned binder used is usually about 1% to 30% by mass, preferably about 2% to 15% by mass relative to the negative electrode active material. In addition, the amount of the solvent used is usually about 10% to 400% by mass, preferably 20% to 200% by mass relative to the negative electrode active material.

As the current collector of the negative electrode, copper, nickel, stainless steel, nickel-plated steel, aluminum, etc. are usually used. The shape of the current collector may be a foil shape, a plate shape, a mesh shape, etc., and a foil shape is preferred. In the case of a foil shape, the thickness of the foil is usually 1 μm to 100 μm.

In the non-aqueous electrolyte power storage device to which the present invention is applicable, a separator is used between the positive electrode and the negative electrode. The separator can be a generally used polymer microporous film, etc., and is not particularly limited. The film can be exemplified by polyethylene, polypropylene, polyvinylidene fluoride, polyvinylidene chloride, polyacrylonitrile, polyacrylamide, polytetrafluoroethylene, polyether, polyether, polycarbonate, poly Polyethers such as amide, polyimide, polyethylene oxide or polypropylene oxide, various celluloses such as carboxymethyl cellulose or hydroxypropyl cellulose, poly(meth)acrylic acid and its A variety of esters, etc. as the main polymer compound or its derivatives, copolymers or mixtures formed films, etc., these films may be ceramic materials such as alumina or silica, or magnesium oxide, aramid resin, In the case of polyvinylidene fluoride coating. In addition, when the non-aqueous solvent electrolyte is a pure polymer electrolyte, it may not contain a spacer.

The applicable non-aqueous electrolyte storage device of the present invention is preferably applicable to non-aqueous electrolyte secondary batteries. The form of the non-aqueous electrolyte secondary battery can be a single cell, a multilayer battery in which a positive electrode and a negative electrode are laminated with a separator in between, or a wound battery in which a long sheet-like separator, a positive electrode and a negative electrode are wound. From the viewpoint of the high charge and discharge capacity of the battery and the possibility of thermal runaway caused by internal short circuit, the present invention is suitable for laminated non-aqueous electrolyte secondary batteries or wound-type non-aqueous electrolyte secondary batteries. The secondary battery is better. [Example]

The following examples and comparative examples illustrate the present invention in detail. However, these examples do not limit the scope of the present invention. In addition, "parts" or "%" in the examples are based on mass unless otherwise specified.

[Preparation of non-aqueous electrolyte] In a mixed solvent of 49.5% by volume of ethylene carbonate, 49.5% by volume of diethyl carbonate, and 1% by volume of vinylene carbonate, LiPF _{6 was} dissolved to 1.0 mol/L The non-aqueous electrolyte of Comparative Example 1 was prepared. In addition, the following phosphoric acid ester compound was dissolved in the non-aqueous electrolyte of Comparative Example 1 to the concentration described in Table 1, and the non-aqueous electrolytes of Examples 1 to 9 and Comparative Examples 2 to 3 were prepared.

_{[Production of positive electrode] Li(Ni 0.6} Co _0.2 Mn _0.2 )O ₂ (produced by Beijing Easpring Material Technology Co., Ltd,) using 94.0 parts by mass as the positive electrode active material, trade name: NCM622), 3.0 parts by mass of acetylene black (manufactured by Denka) as a conductive aid, and 3.0 parts by mass of polyvinylidene fluoride (manufactured by Kureha) as a binder are mixed to 90 parts by mass of N-methylpyrrolidone, using a rotation/revolution mixer , Disperse, prepare mud. The slurry composition was continuously coated on both sides of a roll-shaped aluminum foil (thickness 20 μm) current collector by the cut-off wheel coater method, and dried at 90°C. The roll was cut into a length of 50 mm and a width of 90 mm, and the electrode mixture layer on one of the horizontal sides (short sides) was removed by 10 mm from the end to expose the current collector, and then vacuum dried at 150°C for 2 hours , Make a positive electrode.

[Manufacture of negative electrode] 96.5 parts by mass of artificial graphite (manufactured by Hitachi Chemical) as an electrode active material, 0.5 parts by mass of acetylene black (manufactured by Denka) as a conductive aid, and 2.0 parts by mass of styrene-butadiene rubber as a binder (aqueous dispersion) , Japan ZEON) and 1.0 parts by mass of sodium carboxymethyl cellulose (made by DAICEL FINECHEM) are mixed to 100 parts by mass of water, and dispersed using a rotation/revolution mixer to prepare a slurry. The slurry composition was continuously coated on both sides of a roll-shaped copper foil (thickness 10 μm) current collector by the cut-off wheel coater method, and dried at 90°C. The roll was cut into a length of 55 mm and a width of 95 mm. The electrode mixture layer on one of the horizontal sides (short sides) was removed by 10 mm from the end to expose the current collector, and then vacuum dried at 150°C for 2 hours , Make a negative electrode.

[Production of laminated battery] The positive electrode and the negative electrode were laminated with a separator (manufactured by Celgard, trade name: Celgard 2325) so that the battery capacity was 3 Ah, and the positive electrode and the negative electrode were respectively provided with the positive electrode terminal and the negative electrode terminal to obtain a laminate. The obtained laminate and the non-aqueous electrolytes of Examples 1 to 9 and Comparative Examples 1 to 3 were housed in an aluminum laminate film to obtain laminated batteries of Examples 1 to 9 and Comparative Examples 1 to 3 .

[Charging method] In a thermostat at 25°C, set the end-of-charge voltage at 4.2V, set the end-of-discharge voltage at 2.75V, charge and discharge once at a charge rate of 0.1C and a discharge rate of 0.1C, and perform degassing treatment. Furthermore, the charge and discharge cycle was carried out 5 times under the same conditions, charged to 4.3V at a charge rate of 0.1C, and then used for testing.

[Nailing test method] A battery with a surface temperature of 23°C was fixed on a phenol resin plate with a hole of 10mm in diameter. In the center of the hole, an iron round nail (N65) with a diameter of 3mm and a length of 65mm was perpendicular to the hole at a speed of 1mm/s. Penetrate the surface of the battery and penetrate 10mm into the battery. After holding for 10 minutes, remove the nail. Table 2 shows the maximum surface temperature of the battery after the nail is pierced into the battery. In addition, the maximum surface temperature is measured by using a thermocouple to measure the temperature of the battery surface 10 mm from the nail piercing part, and the temperature when the temperature rises to the maximum is defined as the maximum surface temperature.

In this test, the increase in surface temperature is caused by a short circuit inside the battery. The results showed that the battery with the non-aqueous electrolyte blended with the phosphoric acid ester compound of the present invention has the highest surface as compared with Comparative Example 1 in which the phosphoric acid ester compound is not blended, and Comparative Examples 2 to 3 in which the phosphoric acid ester compound is blended. The temperature is greatly reduced, or thermal runaway caused by internal short circuit is not easy to occur.

Claims (4)

A thermal runaway inhibitor, which is a thermal runaway inhibitor for a non-aqueous electrolyte power storage device containing a phosphate compound represented by the following general formula (1), and the non-aqueous electrolyte power storage device has: a positive electrode containing a positive electrode active material, The negative electrode and the non-aqueous electrolyte containing the negative electrode active material, the aforementioned thermal runaway is the thermal runaway caused by the internal short circuit of the non-aqueous electrolyte power storage device,

(In the formula, R ¹ to R ⁴ are independent of each other and represent a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 4 carbon atoms, X ¹ represents a group represented by general formula (2) or general formula (3), and a represents 0 Or a number from 1 to 4)

(In the formula, R ⁵ to R ⁸ are independent of each other and represent a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 4 carbon atoms, and X ² represents a direct bond, an oxygen atom, a sulfur atom, a sulfinyl group, a sulfinyl group, Or the base represented by the following general formula (4), b represents the number of 0 or 1, and * represents the bonding bond)

(In the formula, R ⁹ to R ¹⁰ are independent of each other and represent a hydrogen atom, a hydrocarbon group with 1 to 10 carbons, a fluorinated alkyl group with 1 to 2 carbons, or a ^{cross-linked R 9} and R ¹⁰ with a carbon number of 5 to The hydrocarbon group of 12, * means bonding bond)

(In the formula, R ¹¹ to R ¹⁴ are independent of each other and represent a hydrogen atom, a fluorine atom, a hydrocarbon group with 1 to 10 carbons, and a fluorinated alkyl group with 1 to 2 carbons, and * represents a bonding bond). Such as the thermal runaway inhibitor of claim 1, wherein a in the general formula (1) represents a number from 1 to 4. A method for suppressing thermal runaway caused by an internal short circuit of a non-aqueous electrolyte power storage device, which includes: blending in a non-aqueous electrolyte at 0.01 to 10% by mass relative to the total amount of the non-aqueous electrolyte, as claimed in claim 1 Or 2 thermal runaway inhibitor. The method for suppressing thermal runaway caused by an internal short circuit of a non-aqueous electrolyte power storage device according to claim 3, wherein the non-aqueous electrolyte is a non-aqueous electrolyte using an organic solvent as a solvent.