JP5631111B2 - Non-aqueous electrolyte and non-aqueous electrolyte secondary battery using the electrolyte - Google Patents

Description

  The present invention relates to a non-aqueous electrolyte used in a secondary battery having a negative electrode containing a polymer carboxylic acid compound, and more specifically, a non-aqueous electrolyte containing an unsaturated phosphate compound having a specific structure. And a non-aqueous electrolyte secondary battery using the electrolyte.

  With the spread of portable electronic devices such as portable personal computers, handy video cameras, and information terminals in recent years, non-aqueous electrolyte secondary batteries having high voltage and high energy density have been widely used as power sources. Also, from the viewpoint of environmental problems, battery cars and hybrid cars using electric power as a part of power have been put into practical use.

  The negative electrode and the positive electrode of the non-aqueous electrolyte secondary battery are mixed with an electrode active material, a conductive material, a binder (binder) and a solvent to form a slurry-like or paste-like coating solution. Manufactured by applying on the body. Examples of the solvent used for manufacturing such a positive electrode or negative electrode include organic solvents such as dimethylacetamide, acetone, dimethylformamide, N-methylpyrrolidone, and water. However, since organic solvents have a large environmental load, In many cases, water is used as the solvent. As the binder or thickener when water is used as a solvent, polymer carboxylic acid compounds such as polyacrylic acid and carboxymethyl cellulose, polyvinyl alcohol, polyethylene glycol, polyvinyl pyrrolidone, polyacrylic amide and the like are used. When a polymer carboxylic acid compound is used, the carboxyl group is adsorbed on the surface of a metal current collector, an electrode active material, a conductive material, etc., so that a good electrode with excellent binding properties can be obtained. It is known (see, for example, Patent Document 1).

  However, a secondary battery having a negative electrode using a polymer carboxylic acid compound has a problem in that a decrease in electric capacity and an increase in internal resistance are likely to occur due to high temperature storage or repeated charge and discharge at a high temperature. Such a problem often occurs in a secondary battery having a negative electrode having a crystalline carbon material such as graphite together with a carboxylic acid compound. This is because decomposition of the polymer carboxylic acid compound occurs at the active site on the negative electrode, particularly at the end face of the highly reactive crystalline carbon material, and a decomposition product is generated on the surface of the negative electrode. It is considered that the reaction with the liquid or the like increases the irreversible capacity and inhibits movement of lithium ions on the negative electrode surface due to accumulation of a large amount of decomposition products.

  On the other hand, for non-aqueous electrolyte secondary batteries, various additives for non-aqueous electrolyte solutions have been proposed in order to improve the stability and electrical characteristics of non-aqueous electrolyte secondary batteries. For example, 1,3-propane sultone (for example, see Patent Document 2), vinyl ethylene carbonate (for example, see Patent Document 3), vinylene carbonate (for example, see Patent Document 4), 1,3-propane sultone, Additives such as butane sultone (for example, see Patent Document 5), vinylene carbonate (for example, see Patent Document 6), vinyl ethylene carbonate (for example, see Patent Document 7) are added to the surface of the negative electrode on SEI (Solid Electrolyte Interface). It is considered that a stable coating called a solid electrolyte membrane) is formed, and this coating covers the surface of the negative electrode, thereby suppressing reductive decomposition of the electrolytic solution. Among these, vinylene carbonate is widely used because of its great effect.

  However, these additives are highly reactive with decomposed products of the polymer carboxylic acid compound at high temperatures in the negative electrode containing the polymer carboxylic acid compound. Sufficient prevention effect was not obtained with respect to a decrease in electric capacity and an increase in internal resistance due to repeated charging and discharging.

  In addition, non-aqueous electrolytes containing tripropagyl phosphate and dimethylpropargyl phosphate (for example, see Patent Documents 8 and 9) have been proposed. Such non-aqueous electrolytes and polymer carboxylic acids are also proposed. There is no suggestion about a non-aqueous electrolyte secondary battery having a negative electrode containing a compound.

  The polymer carboxylic acid compound may be used after neutralization or partial neutralization with amines or alkali metals in order to improve water solubility or adjust pH. The neutralized product and partially neutralized product of the polymer carboxylic acid compound are referred to as a polymer carboxylic acid compound.

JP 2007-115671 A JP 63-102173 A JP-A-4-87156 Japanese Patent Laid-Open No. 5-74486 Japanese Patent Laid-Open No. 10-50342 JP-A-8-045545 JP 2001-6729 A JP 2002-198092 A US Pat. No. 6,511,772

  Therefore, an object of the present invention is also in a non-aqueous electrolyte secondary battery using a negative electrode manufactured using a crystalline carbon material having high crystallinity such as graphite as an active material and a polymer carboxylic acid compound as a binder. Another object of the present invention is to provide a non-aqueous electrolyte for a secondary battery capable of maintaining a small internal resistance and a high electric capacity during long-term use, and a non-aqueous electrolyte secondary battery using the electrolyte.

（式中、Ｒ¹及びＲ²は各々独立して水素原子又は炭素数１〜８のアルキル基を表わし、Ｒ³は炭素数１〜８のアルキル基、炭素数２〜８のアルケニル基、炭素数２〜８のアルキニル基又は炭素数１〜８のハロゲン化アルキル基を表わす。） As a result of intensive studies, the present inventors have found that the above problems can be solved by adding an unsaturated phosphate ester compound having a specific structure to the nonaqueous electrolytic solution, and have completed the present invention.
That is, this invention contains the unsaturated phosphate ester compound represented by following General formula (1) in the non-aqueous electrolyte used for the secondary battery which has a negative electrode containing a polymeric carboxylic acid compound. The non-aqueous electrolyte characterized by these is provided.

(Wherein R ¹ and R ² each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R ³ represents an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, carbon Represents an alkynyl group having 2 to 8 carbon atoms or a halogenated alkyl group having 1 to 8 carbon atoms.)

  Moreover, this invention provides the nonaqueous electrolyte secondary battery which has a negative electrode containing a polymeric carboxylic acid compound, a positive electrode, and the said nonaqueous electrolyte.

  According to the nonaqueous electrolytic solution of the present invention, it has become possible to greatly extend the life of a nonaqueous electrolytic solution secondary battery having a negative electrode containing a polymeric carboxylic acid compound. In particular, in a non-aqueous electrolyte secondary battery having a negative electrode containing the polymer carboxylic acid compound and a crystalline carbon material, it becomes possible to maintain a small internal resistance and a high electric capacity in long-term use. It has become possible to greatly extend the life of liquid secondary batteries.

FIG. 1 is a longitudinal sectional view schematically showing an example of the structure of a coin-type battery of the nonaqueous electrolyte secondary battery of the present invention. FIG. 2 is a schematic diagram showing a basic configuration of a cylindrical battery of the nonaqueous electrolyte secondary battery of the present invention. FIG. 3 is a perspective view showing the internal structure of the cylindrical battery of the nonaqueous electrolyte secondary battery of the present invention as a cross section.

Hereinafter, the present invention will be described in detail based on preferred embodiments.
First, the nonaqueous electrolytic solution of the present invention will be described.
The nonaqueous electrolytic solution of the present invention contains an unsaturated phosphate compound represented by the general formula (1).

In the general formula (1), R ¹ and R ² each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. Examples of the alkyl group having 1 to 8 carbon atoms include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, secondary butyl, t-butyl, pentyl, isopentyl, secondary pentyl, t-pentyl, hexyl, and secondary hexyl. , Heptyl, secondary heptyl, octyl, secondary octyl, 2-methylpentyl, 2-ethylhexyl and the like. R ¹ and R ² are preferably a hydrogen atom, methyl, ethyl, and propyl, more preferably a hydrogen atom and methyl, and most preferably a hydrogen atom, since there are few adverse effects on the movement of lithium ions and charging characteristics are good. .

R ³ represents an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, an alkynyl group having 2 to 8 carbon atoms, or a halogenated alkyl group having 1 to 8 carbon atoms. Examples of the alkyl group having 1 to 8 carbon atoms include the alkyl groups exemplified for R ¹ and R ² . Examples of the alkenyl group having 2 to 8 carbon atoms include vinyl, allyl, 3-butenyl, isobutenyl, 4-pentenyl, 5-hexenyl, 6-heptenyl, 7-octenyl and the like. Examples of the alkynyl group having 2 to 8 carbon atoms include ethynyl, 2-propynyl (also referred to as propargyl), 3-butynyl, 1-methyl-2-propynyl, 1,1-dimethyl-2-propynyl and the like. Examples of the halogenated alkyl group having 1 to 8 carbon atoms include chloromethyl, trifluoromethyl, 2-fluoroethyl, 2-chloroethyl, 2,2,2-trifluoroethyl, 2,2,2-trichloroethyl, 1,1,2,2-tetrafluoroethyl, pentafluoroethyl, 3-fluoropropyl, 2-chloropropyl, 3-chloropropyl, 2-chloro-2-propyl, 3,3,3-trifluoropropyl, , 2,3,3-tetrafluoropropyl, heptafluoropropyl, 2-chlorobutyl, 3-chlorobutyl, 4-chlorobutyl, 3-chloro-2-butyl, 1-chloro-2-butyl, 2-chloro-1,1 -Dimethylethyl, 3-chloro-2-methylpropyl, 5-chloropentyl, 3-chloro-2-methylpropyl, 3-chloro- , 2-dimethyl, 6-chloro-hexyl and the like. R ³ is preferably methyl, ethyl, propyl, butyl, pentyl, 2-chlorobutyl, 2-propynyl, 3-chlorobutyl, or 4-chlorobutyl because the internal resistance of the nonaqueous electrolyte secondary battery is reduced. , Propyl and butyl are more preferable, and ethyl is most preferable.

Among the unsaturated phosphate compounds represented by the general formula (1), examples of the compound in which R ¹ and R ² are hydrogen atoms include methyl bis (2-propynyl) phosphate and ethyl bis (2-propynyl). Phosphate, propyl bis (2-propynyl) phosphate, butyl bis (2-propynyl) phosphate, pentyl bis (2-propynyl) phosphate, allyl bis (2-propynyl) phosphate, tris (2-propynyl) phosphate, 2 -Chloroethylbis (2-propynyl) phosphate, 2,2,2-trifluoroethylbis (2-propynyl) phosphate, 2,2,2-trichloroethylbis (2-propynyl) phosphate, etc. .

Examples of the compound in which R ¹ is methyl and R ² is a hydrogen atom include, for example, methyl bis (1-methyl-2-propynyl) phosphate, ethyl bis (1-methyl-2-propynyl) phosphate, propyl bis ( 1-methyl-2-propynyl) phosphate, butyl bis (1-methyl-2-propynyl) phosphate, pentyl bis (1-methyl-2-propynyl) phosphate, allyl bis (1-methyl-2-propynyl) phosphate, Tris (1-methyl-1-methyl-2-propynyl) phosphate, 2-chloroethylbis (1-methyl-2-propynyl) phosphate, 2,2,2-trifluoroethylbis (1-methyl-2) -Propynyl) phosphate, 2,2,2-trichloroethylbis (1-methyl-2- Propynyl) phosphate and the like.

  Examples of the unsaturated phosphate compound represented by the general formula (1) include methyl bis (2-propynyl) phosphate, ethyl bis (2-propynyl) phosphate, propyl bis (2-propynyl) phosphate, butyl bis (2 -Propynyl) phosphate, pentylbis (2-propynyl) phosphate, tris (2-propynyl) phosphate, 2-chloroethylbis (2-propynyl) phosphate are preferred, ethylbis (2-propynyl) phosphate, propylbis More preferred are (2-propynyl) phosphate and butyl bis (2-propynyl) phosphate, and most preferred is ethyl bis (2-propynyl) phosphate.

  In the nonaqueous electrolytic solution of the present invention, when the content of the unsaturated phosphate ester compound represented by the general formula (1) is too small, a sufficient effect cannot be exhibited, and when the content is too large, However, the content of the unsaturated phosphate ester compound represented by the general formula (1) is not non-existent. In the aqueous electrolyte, 0.001 to 5 mass% is preferable, 0.01 to 4 mass% is more preferable, and 0.03 to 3 mass% is most preferable.

（式中、Ｒ⁴及びＲ⁵は各々独立して水素原子又は炭素数１〜８のアルキル基を表わし、Ｒ⁶及びＲ⁷は各々独立して炭素数１〜８のアルキル基、炭素数２〜８のアルケニル基又は炭素数２〜８のアルキニル基を表わす。）

（式中、Ｒ⁸及びＲ⁹は各々独立して水素原子又は炭素数１〜８のアルキル基を表わす。） The non-aqueous electrolyte of the present invention further improves the stability of the coating film formed on the negative electrode surface at a high temperature and maintains the electric capacity of the non-aqueous electrolyte secondary battery over a long period of time. It is preferable to contain the unsaturated silane compound represented by these, or the unsaturated borate ester compound represented by following General formula (3).

(In the formula, R ⁴ and R ⁵ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms; R ⁶ and R ⁷ each independently represent an alkyl group having 1 to 8 carbon atoms; Represents an alkenyl group having -8 or an alkynyl group having 2 to 8 carbon atoms.)

(In the formula, R ⁸ and R ⁹ each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.)

In the general formula (2), R ⁴ and R ⁵ each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. Examples of the alkyl group having 1 to 8 carbon atoms, for example, alkyl groups exemplified for R ¹ and R ² in the general formula (1). R ⁴ and R ⁵ are preferably a hydrogen atom, methyl, ethyl, or propyl, more preferably a hydrogen atom or methyl, and most preferably a hydrogen atom, since there is little adverse effect on the movement of lithium ions and good charging characteristics. .

In the general formula (2), R ⁶ and R ⁷ each independently represents an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, or an alkynyl group having 2 to 8 carbon atoms. Examples of the alkyl group having 1 to 8 carbon atoms, for example, alkyl groups exemplified for R ¹ and R ² in the general formula (1). As a C2-C8 alkenyl group, the alkenyl group illustrated by R < ³ > of the said General formula (1) can be mentioned, for example. As a C2-C8 alkynyl group, the alkynyl group illustrated by R < ³ > of the said General formula (1) can be mentioned, for example. R ⁶ and R ⁷ are preferably methyl, ethyl, propyl, vinyl, allyl, butenyl, and 2-propynyl because they have little adverse effect on the movement of lithium ions and good charge characteristics, and methyl, ethyl, propyl, More preferred are vinyl and 2-propynyl, and most preferred is methyl and 2-propynyl.

  Examples of the unsaturated silane compound represented by the general formula (2) include dimethylbis (2-propynyl) silane, diethylbis (2-propynyl) silane, ethylmethylbis (2-propynyl) silane, methylvinylbis ( 2-propynyl) silane, methyltris (2-propynyl) silane, tetrakis (2-propynyl) silane, and the like. Dimethylbis (2-propynyl) silane, methyltris (2-propynyl) silane, tetrakis (2-propynyl) silane Are preferred, methyltris (2-propynyl) silane and tetrakis (2-propynyl) silane are more preferred, and tetrakis (2-propynyl) silane is most preferred.

In the general formula (3), R ⁸ and R ⁹ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. Examples of the alkyl group having 1 to 8 carbon atoms, for example, alkyl groups exemplified for R ¹ and R ² in the general formula (1). R ⁸ and R ⁹ are preferably a hydrogen atom, methyl, ethyl, or propyl, more preferably a hydrogen atom or methyl, and most preferably a hydrogen atom, since there is little adverse effect on the movement of lithium ions and good charge characteristics. .

  Examples of the unsaturated borate compound represented by the general formula (3) include tris (2-propynyl) borate, tris (1-methyl-2-propynyl) borate, and tris (1-ethyl-2-propynyl). ) Borate and tris (1,1-dimethyl-2-propynyl) borate, and tris (2-propynyl) borate is preferred.

  The unsaturated silane compound represented by the general formula (2) and the unsaturated borate compound represented by the general formula (3) may be used alone or in combination of two or more. May be. When using only 1 type, the unsaturated silane compound represented by the said General formula (2) is preferable.

  In the nonaqueous electrolytic solution of the present invention, it is sufficient when the content of the unsaturated silane compound represented by the general formula (2) and the unsaturated borate compound represented by the general formula (3) is too small. If the amount is too large, the effect of increasing the amount corresponding to the blending amount cannot be obtained, but the characteristics of the non-aqueous electrolyte may be adversely affected. The content of the unsaturated silane compound represented and the unsaturated borate compound represented by the general formula (3) is preferably 0.001 to 5% by mass in the nonaqueous electrolytic solution, and 0.003 to 4% by mass. % Is more preferable, and 0.005 to 3 mass% is most preferable.

（式中、Ｒ¹⁰は炭素数２〜８のアルケニル基又は炭素数２〜８のアルキニル基を表わし、Ｒ¹¹、Ｒ¹²及びＲ¹³は各々独立して、エーテル基又はハロゲン原子を有してもよい炭素数１〜８のアルキル基又はアルケニル基を表す。） The non-aqueous electrolyte of the present invention reduces the generation of free acid in the electrolyte, suppresses the decomposition of the electrolyte and the electrode active material, and reduces the internal resistance of the non-aqueous electrolyte secondary battery. Furthermore, it is preferable to contain an unsaturated carboxylic acid silyl ester compound represented by the following general formula (4).

(In the formula, R ¹⁰ represents an alkenyl group having 2 to 8 carbon atoms or an alkynyl group having 2 to 8 carbon atoms, and R ¹¹ , R ¹² and R ¹³ each independently have an ether group or a halogen atom. Represents a C1-C8 alkyl group or alkenyl group.

In the general formula (4), R ¹⁰ represents an alkenyl group having 2 to 8 carbon atoms or an alkynyl group having 2 to 8 carbon atoms. As a C2-C8 alkenyl group and a C2-C8 alkynyl group, the alkenyl group illustrated by R < ³ > of the said General formula (1) and C2-C8 alkynyl can be mentioned, for example. As R ¹⁰ , vinyl, 1-propenyl, isopropenyl, 1-butenyl, ethynyl, and 1-propynyl are preferable because vinyl ions, 1-propenyl, isopropenyl, 1-butenyl, ethynyl, and 1-propynyl are preferable because there is little adverse effect on the movement of lithium ions. Propinyl is more preferred.

In the general formula (4), R ¹¹ , R ¹² and R ¹³ each independently represent an alkyl group or alkenyl group having 1 to 8 carbon atoms which may have an ether group or a halogen atom. R ¹¹ , R ¹² and R ¹³ are each an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms and a halogenated alkyl having 1 to 8 carbon atoms exemplified as R ³ in the general formula (4). In addition to the groups 3-methoxypropyl, 3-ethoxypropyl, 3-propoxypropyl, 4-methoxybutyl, 4-ethoxybutyl, 4-propoxybutyl, 4-butoxybutyl, 3-methoxy-2-methylpropyl, 3 Examples thereof include alkyl groups having an ether group such as ethoxy-2-methylpropyl and 3-propoxy-2-methylpropyl. As R ¹¹ , R ¹² and R ¹³ , methyl and ethyl are preferable, and methyl is more preferable because it has less adverse effect on the movement of lithium ions and good charge characteristics.

  Preferable specific examples of the unsaturated carboxylic acid silyl ester compound represented by the general formula (4) include trimethylsilyl acrylate, trimethylsilyl methacrylate, trimethylsilyl crotonic acid, trimethylsilyl 2-butenoate, and 2-methyl-2-butenoic acid. Trimethylsilyl, trimethylsilyl 2-pentenoate, trimethylsilyl 2-hexenoate, trimethylsilyl 2-heptenoate, trimethylsilyl 2-octenoate, trimethylsilyl 2-nonenate, trimethylsilyl propinate, trimethylsilyl 2-butynoate, trimethylsilyl 2-pentenoate, 2- Examples include trimethylsilyl hexinate, trimethylsilyl 2-heptate, trimethylsilyl 2-octyneate, trimethylsilyl 2-noninate, and the like. Among them, trimethylsilyl acrylate Trimethylsilyl methacrylate, 2-pentenoic acid trimethylsilyl propionic acid trimethylsilyl and 2-butyne-trimethylsilyl Preferably, trimethylsilyl acrylate, propionic acid trimethylsilyl and 2-butyne-trimethylsilyl more preferred.

  Only one type of unsaturated carboxylic acid silyl ester compound represented by the general formula (4) may be used, or two or more types may be used in combination.

  In the nonaqueous electrolytic solution of the present invention, when the content of the unsaturated carboxylic acid silyl ester compound represented by the general formula (4) is too small, a sufficient effect cannot be exhibited, and when the content is too large, The content of the unsaturated carboxylic acid silyl ester compound represented by the general formula (4) is not limited to the effect of increasing the amount corresponding to the blending amount but may adversely affect the characteristics of the non-aqueous electrolyte. Is preferably 0.001 to 5 mass%, more preferably 0.003 to 4 mass%, and most preferably 0.005 to 3 mass% in the non-aqueous electrolyte.

  The non-aqueous electrolyte of the present invention further comprises a cyclic carbonate compound, a chain carbonate compound, and an unsaturated diester having an unsaturated group in order to form a film on the electrode surface that matches the characteristics of the active material of each of the positive electrode and the negative electrode. It is preferable to contain one or more compounds selected from the group consisting of a compound, a halogenated cyclic carbonate compound, a cyclic sulfite compound and a cyclic sulfate compound.

  Examples of the cyclic carbonate compound having an unsaturated group include vinylene carbonate, vinyl ethylene carbonate, propylidene carbonate, ethylene ethylidene carbonate, ethylene isopropylidene carbonate, and vinylene carbonate or vinyl ethylene carbonate is preferable.

  Examples of the chain carbonate compound include dipropargyl carbonate, propargyl methyl carbonate, ethyl propargyl carbonate, bis (1-methylpropargyl) carbonate, and bis (1-dimethylpropargyl) carbonate.

  Examples of the unsaturated diester compounds include dimethyl maleate, diethyl maleate, dipropyl maleate, dibutyl maleate, dipentyl maleate, dihexyl maleate, diheptyl maleate, dioctyl maleate, dimethyl fumarate, diethyl fumarate, and fumaric acid. Dipropyl, dibutyl fumarate, dipentyl fumarate, dihexyl fumarate, diheptyl fumarate, dioctyl fumarate, dimethyl acetylenedicarboxylate, diethyl acetylenedicarboxylate, dipropyl acetylenedicarboxylate, dibutyl acetylenedicarboxylate, dipentyl acetylenedicarboxylate, acetylenedicarboxylic acid Examples include dihexyl, diheptyl acetylenedicarboxylate, and dioctyl acetylenedicarboxylate.

  Examples of the halogenated cyclic carbonate compound include chloroethylene carbonate, dichloroethylene carbonate, fluoroethylene carbonate, and difluoroethylene carbonate. Examples of the sulfite ester compound include ethylene sulfite. Examples of the cyclic sulfate compound include Propane sultone, butane sultone and the like.

  Among these compounds, vinylene carbonate, vinyl ethylene carbonate, dipropargyl carbonate, dimethyl acetylenedicarboxylate, diethyl acetylenedicarboxylate, chloroethylene carbonate, dichloroethylene carbonate, fluoroethylene carbonate, ethylene sulfite, propane sultone, butane sultone are preferable, and vinylene carbonate. , Dipropargyl carbonate, dimethyl acetylenedicarboxylate, chloroethylene carbonate, fluoroethylene carbonate, ethylene sulfite, and propane sultone are more preferable, and vinylene carbonate, dipropargyl carbonate, chloroethylene carbonate, fluoroethylene carbonate, ethylene sulfite, and propane sultone are preferable. Most favorable Arbitrariness.

  These compounds may be used alone or in combination of two or more.

  In the nonaqueous electrolytic solution of the present invention, if the content of these compounds is too small, a sufficient effect cannot be exhibited, and if it is too large, not only an increase effect corresponding to the blending amount is not obtained, but on the contrary. The content of these compounds is preferably 0.005 to 10% by mass, more preferably 0.02 to 5% by mass in the nonaqueous electrolyte because it may adversely affect the characteristics of the nonaqueous electrolyte. 0.05 to 3 mass% is most preferable.

  As an organic solvent used for the non-aqueous electrolyte of this invention, what is normally used for the non-aqueous electrolyte can be used 1 type or in combination of 2 or more types. Specific examples include a cyclic carbonate compound, a cyclic ester compound, a sulfone or sulfoxide compound, an amide compound, a chain carbonate compound, a chain ether compound, a cyclic ether compound, and a saturated chain ester compound.

  Among the organic solvents, the cyclic carbonate compound, the cyclic ester compound, the sulfone or sulfoxide compound, and the amide compound have a high relative dielectric constant, and thus serve to increase the dielectric constant of the electrolytic solution. Among these compounds, a cyclic carbonate compound is particularly preferable.

  Specifically, examples of the cyclic carbonate compound include ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate, and isobutylene carbonate. Examples of the cyclic ester compound include γ-butyrolactone and γ-valerolactone. Examples of the sulfone or sulfoxide compound include sulfolane, sulfolene, tetramethyl sulfolane, diphenyl sulfone, dimethyl sulfone, dimethyl sulfoxide, and the like, and sulfolane and tetramethyl sulfolane are preferable. Examples of the amide compound include N-methylpyrrolidone, dimethylformamide, dimethylacetamide and the like.

  Among the organic solvents, the chain carbonate compound, the chain ether compound, the cyclic ether compound, and the saturated chain ester compound can reduce the viscosity of the non-aqueous electrolyte and increase the mobility of electrolyte ions. Battery characteristics such as output density can be made excellent. Moreover, since it is low-viscosity, the performance of the non-aqueous electrolyte at low temperatures can be increased. Among these compounds, a chain carbonate compound is preferable.

  Specifically, as the chain carbonate compound, dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), ethyl-butyl carbonate, methyl-t-butyl carbonate, di-isopropyl carbonate, t -Butyl-propyl carbonate and the like.

  Examples of the chain or cyclic ether compound include dimethoxyethane (DME), ethoxymethoxyethane, diethoxyethane, tetrahydrofuran, dioxolane, dioxane, 1,2-bis (methoxycarbonyloxy) ethane, 1,2-bis (ethoxycarbonyl). Oxy) ethane, 1,2-bis (ethoxycarbonyloxy) propane, ethylene glycol bis (trifluoroethyl) ether, propylene glycol bis (trifluoroethyl) ether, ethylene glycol bis (trifluoromethyl) ether, diethylene glycol bis (tri Fluoroethyl) ether and the like, and among these compounds, dioxolanes are preferred.

  As the saturated chain ester compound, monoester compounds and diester compounds having a total number of carbon atoms in the molecule of 2 to 8 are particularly preferable. Specific compounds include methyl formate, ethyl formate, methyl acetate, and acetic acid. Ethyl, propyl acetate, isobutyl acetate, butyl acetate, methyl propionate, ethyl propionate, methyl butyrate, methyl isobutyrate, methyl trimethyl acetate, ethyl trimethyl acetate, methyl malonate, ethyl malonate, methyl succinate, ethyl succinate, Examples include methyl 3-methoxypropionate, ethyl 3-methoxypropionate, ethylene glycol diacetyl, propylene glycol diacetyl, and the like. Methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, isobutyl acetate, butyl acetate, methyl propionate , Ethyl acid are preferred.

  As the organic solvent of the nonaqueous electrolytic solution of the present invention, one or more solvents (solvent A) selected from the group consisting of cyclic carbonate compounds, cyclic ester compounds, sulfone or sulfoxide compounds and amide compounds, chain carbonate compounds, A mixed solvent with one or more solvents (solvent B) selected from the group consisting of a chain ether compound, a cyclic ether compound and a saturated chain ester compound not only has excellent cycle characteristics, but also the viscosity of the non-aqueous electrolyte, It is preferable because it can provide a non-aqueous electrolyte in which the electric capacity and output of the obtained battery are balanced, and in particular, a mixed solvent of a cyclic carbonate compound and a chain carbonate compound greatly improves battery characteristics at low temperatures. Is more preferable because In addition, the mixing ratio of the solvent A and the solvent B is preferably 1:10 to 10: 1, more preferably 2:10 to 10: 5 on a mass basis.

  Moreover, it becomes possible to improve the battery characteristic in low temperature by containing the said saturated chain ester compound as an organic solvent. The content of the saturated chain ester compound is preferably 0.5 to 30% by mass, and more preferably 1 to 10% by mass in the nonaqueous electrolytic solution.

  In addition, acetonitrile, propionitrile, nitromethane, and derivatives thereof can also be used as the organic solvent.

  In addition, halogen-based, phosphorus-based, and other flame retardants can be appropriately added to the nonaqueous electrolytic solution of the present invention in order to impart flame retardancy. Examples of the phosphorus flame retardant include phosphate esters such as trimethyl phosphate and triethyl phosphate. If the amount of flame retardant added is too small, sufficient flame retarding effect cannot be exerted.If it is too large, not only an increase effect corresponding to the blending amount can be obtained, but on the other hand, the characteristics of the non-aqueous electrolyte Since the adverse effect may occur, the amount of the flame retardant added is preferably 5 to 100% by mass, and 10 to 50% by mass with respect to the organic solvent constituting the nonaqueous electrolytic solution of the present invention. More preferably.

As the electrolyte salt used in the nonaqueous electrolytic solution of the present invention, a conventionally known electrolyte salt is used. For example, LiPF ₆ , LiBF ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiCF ₃ CO ₂ , LiN (CF _{3 SO 2) 2, LiC (CF} 3 SO 2) 3, LiB (CF 3 SO 3) 4, LiB (C 2 O 4) 2, LiSbF 6, LiSiF 5, LiAlF 4, LiSCN, LiClO 4, LiCl, LiF, Examples include LiBr, LiI, LiAlF ₄ , LiAlCl ₄ , NaClO ₄ , NaBF ₄ , NaI, and derivatives thereof. Among these, LiPF ₆ , LiBF ₄ , LiClO ₄ , LiAsF ₆ , LiCF ₃ SO ₃ , LiN ( CF ₃ SO ₂₎ derivatives of ₂ and LiC (CF ₃ SO _{2) 3} and _{LiCF 3 SO 3, LiN (CF} 3 SO 2) 2 derivative The use at least one member selected from fine LiC (CF ₃ SO ₂₎ group consisting of ₃ derivatives, because of excellent electrical characteristics preferred.

  The electrolyte salt can be dissolved in the organic solvent so that the concentration in the nonaqueous electrolytic solution of the present invention is 0.1 to 3.0 mol / L, particularly 0.5 to 2.0 mol / L. preferable. If the concentration of the electrolyte salt is less than 0.1 mol / L, a sufficient current density may not be obtained, and if it is more than 3.0 mol / L, the stability of the non-aqueous electrolyte may be impaired.

  The non-aqueous electrolyte solution of the present invention described above is a non-aqueous electrolyte solution constituting a secondary battery, preferably a lithium ion secondary battery, more preferably a lithium ion secondary battery having a negative electrode containing a polymer carboxylic acid compound. It can also be used as a non-aqueous electrolyte for primary batteries.

Next, the nonaqueous electrolyte secondary battery of the present invention will be described.
The non-aqueous electrolyte secondary battery of the present invention has a negative electrode, a positive electrode, and a non-aqueous electrolyte containing a polymer carboxylic acid compound, and the non-aqueous electrolyte of the present invention is used as the non-aqueous electrolyte. It is.

  The negative electrode is prepared by applying a slurry obtained by slurrying a negative electrode active material and a binder (binder) with an organic solvent or an aqueous solvent (for example, water) onto a metal current collector, drying, and rolling as necessary. The polymer carboxylic acid compound is used as a binder when producing a negative electrode or as a thickener when slurried with an aqueous solvent. The polymer carboxylic acid compound has good dispersibility in an aqueous solvent by adsorbing its carboxyl group to the surface of a metal current collector, electrode active material, conductive material, etc. Excellent binding properties can be obtained.

  Examples of the polymer carboxylic acid compound include polyacrylic acid, polymethacrylic acid, acrylic acid / olefin copolymer, acrylic acid / maleic acid copolymer, methacrylic acid / olefin copolymer, methacrylic acid / maleic acid copolymer, fumaric acid / styrene. Copolymers, fumaric acid / C2-5 olefin copolymers, maleic acid / styrene copolymers, maleic acid / C2-5 olefin copolymers, carboxymethylcellulose, alginic acid and the like. Examples of C2-5 olefins of fumaric acid / C2-5 olefin copolymer and maleic acid / C2-5 olefin copolymer include ethylene, propylene, 1-butene, 2-butene, isobutene, 1-propylene, 2-propylene, 1 -Propylene, 2-propylene, isopropylene, cyclopropylene, etc. are mentioned.

  Among the above polymer carboxylic acid compounds, polyacrylic acid and carboxymethylcellulose are preferable, and carboxymethylcellulose is more preferable because an electrode having excellent dispersibility of the crystalline carbon material and excellent resistance to electrolytic solution can be obtained. The polymer carboxylic acid compound is preferably a neutralized product or a partially neutralized product from the viewpoint of solubility in water and dispersibility in water of electrode active materials, conductive materials, etc., and neutralization with an alkali metal. More preferably, it is a product or a partially neutralized product. Examples of such alkali metals include lithium, sodium, potassium, rubidium, and cesium. Among them, lithium, sodium, and potassium are preferable, lithium and sodium are more preferable, and lithium is most preferable.

  When the polyacrylic acid is used, if the molecular weight is too small, the binding force decreases, and if the molecular weight is too large, the viscosity of the slurry becomes too high and the workability decreases, so the mass average molecular weight is 30,000 to 1500,000. What is is preferable and what is 50000-300000 is still more preferable.

  Moreover, when using the said carboxymethylcellulose, that whose etherification degree (the number of carboxymethyl ether groups per glycol unit) is 0.6-1.1 is preferable, and what is 0.8-1.0 When the lithium salt or sodium salt of carboxymethyl cellulose is used, a 1% by weight aqueous solution having a viscosity at 20 ° C. of 500 to 5000 mPa · s is preferable, and 900 to 3000 mPa · s is more preferable.

  If the amount of the polymer carboxylic acid compound used is too small, the dispersibility of the negative electrode active material may be insufficient, and the negative electrode active material may be unevenly distributed in the negative electrode. If the amount used is too large, the polymer carboxylic acid may be Coating the negative electrode active material, which may adversely affect the movement of lithium ions and generate resistance. Therefore, the amount of the polymeric carboxylic acid compound used is based on 100 parts by mass of the negative electrode active material. 0.001-5 mass parts is preferable, 0.05-3 mass parts is still more preferable, and 0.01-2 mass parts is the most preferable.

As the negative electrode active material, in addition to crystalline carbon materials such as artificial graphite and natural graphite, simple metals such as lithium, tin, zinc and aluminum and alloys containing these metals are used. The material is widely used. The surface of the crystalline carbon is highly reactive, but when used as a negative electrode active material, the surface area increases to about ² to 5 m ² / g by microcrystallization, and a polymer is formed on the surface of the crystalline carbon. This is a cause of the decomposition reaction of carboxylic acid compounds and the like. According to the nonaqueous electrolytic solution of the present invention, it is possible to reduce the decomposition reaction of the polymer carboxylic acid compound even in the negative electrode in which crystalline carbon is used as the negative electrode active material.

  In addition, for the purpose of improving the conductivity in the electrode, furnace black, acetylene black, ketjen black, mesocarbon microbeads (MCMB), vapor grown carbon fiber (VGCF), carbon nanofiber, etc. Conductive materials such as styrene-butadiene rubber (SBR), polyvinyl chloride, polyvinyl pyrrolidone, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyimide, polyvinyl alcohol, methyl cellulose, hydroxyethyl cellulose, and other high molecular carboxylic acid compounds. Other binders or thickeners may be contained. In addition, 0.01-10 mass parts is preferable with respect to 100 mass parts of negative electrode active materials, and, as for the usage-amount of the said electrically conductive material, 0.1-5 mass parts is still more preferable. Moreover, 0.01-5 mass parts is preferable with respect to 100 mass parts of negative electrode active materials, and, as for the usage-amount of binders or thickeners other than the said polymeric carboxylic acid, 0.1-2 mass parts is still more preferable.

  As the solvent to be slurried, an aqueous solvent such as an organic solvent or water is used, and an aqueous solvent is preferably used. Moreover, as this organic solvent, the thing similar to what is used with a positive electrode is mentioned. In addition, the usage-amount of the said solvent has preferable 30-400 mass parts with respect to 100 mass parts of said high molecular carboxylic acid compounds, and 50-300 mass parts is still more preferable.

  In addition, copper, nickel, stainless steel, nickel-plated steel, aluminum or the like is usually used for the negative electrode current collector.

  As the positive electrode, a positive electrode active material, a binder (binder), and a conductive material slurried with an organic solvent or an aqueous solvent (for example, water) are applied to a current collector and dried. A rolled sheet is used.

The positive electrode active material is not particularly limited as long as it can electrochemically occlude and release lithium ions, but is preferably a compound containing lithium and at least one transition metal. Examples thereof include metal composite oxides, lithium-containing transition metal phosphate compounds, and the like. As the transition metal of the lithium transition metal composite oxide, vanadium, titanium, chromium, manganese, iron, cobalt, nickel, copper and the like are preferable. Specific examples of the lithium transition metal composite oxide include lithium cobalt composite oxide such as LiCoO ₂ , lithium nickel composite oxide such as LiNiO ₂ , and lithium manganese composite oxide such as LiMnO ₂ , LiMn ₂ O ₄ , and Li ₂ MnO _3. Some of the transition metal atoms that are the main components of these lithium transition metal composite oxides are aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, lithium, nickel, copper, zinc, magnesium, gallium, zirconium, etc. The thing substituted with the other metal etc. are mentioned. Specific examples of the substituted ones include, for example, LiNi _0.5 Mn _0.5 O ₂ , LiNi _0.80 Co _0.17 Al _0.03 O ₂ , LiNi _1/3 Co _1/3 Mn _1/3 O ₂ , LiMn _1.8 Al _0.2 O ₄ , LiMn _1.5 Ni _0.5 O ₄ or the like. As the transition metal of the lithium-containing transition metal phosphate compound, vanadium, titanium, manganese, iron, cobalt, nickel and the like are preferable. Specific examples include, for example, lithium iron phosphate compounds such as LiFePO ₄ and phosphorus such as LiCoPO _4. Cobalt lithium compounds, some of the transition metal atoms that are the main components of these lithium-containing transition metal phosphate compounds are aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, lithium, nickel, copper, zinc, magnesium, gallium , Substituted with other metals such as zirconium and niobium.

  As the positive electrode active material used for the positive electrode of the nonaqueous electrolyte secondary battery of the present invention, a lithium compound containing cobalt, particularly a lithium cobalt composite oxide, is preferable because a high voltage can be stably obtained. Since a high voltage is obtained and the raw material is inexpensive, manganese, iron or nickel, in particular, a lithium compound containing iron or nickel is more preferable, and a lithium nickel-containing composite oxide or a part of its nickel atom is another metal. More preferably, the lithium iron phosphate compound or a part of its iron atom is substituted with another metal. A positive electrode having a positive electrode active material containing nickel or iron has a problem that a high-temperature deterioration reaction of the non-aqueous electrolyte is likely to occur. However, the non-aqueous electrolyte for a secondary battery of the present invention is represented by the general formula (1). By containing the unsaturated phosphoric acid ester compound represented, it was possible to maintain a small internal resistance and a high electric capacity even after high-temperature storage, with little decomposition of the non-aqueous electrolyte.

  Examples of the positive electrode binder include, but are not limited to, polyvinylidene fluoride, polytetrafluoroethylene, EPDM, SBR, NBR, fluororubber, and polyacrylic acid. In addition, 0.1-20 mass parts is preferable with respect to 100 mass parts of positive electrode active materials, and, as for the usage-amount of the said binder, 0.5-10 mass parts is still more preferable.

  Examples of the conductive material for the positive electrode include graphite fine particles, carbon black such as acetylene black and ketjen black, amorphous carbon fine particles such as needle coke, and the like, but are not limited thereto. In addition, 0.01-20 mass parts is preferable with respect to 100 mass parts of positive electrode active materials, and, as for the usage-amount of the said electrically conductive material, 0.1-10 mass parts is still more preferable.

  As the solvent for forming a slurry, an organic solvent that dissolves the binder or an aqueous solvent such as water is used. Examples of the organic solvent include N-methylpyrrolidone, dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, NN-dimethylaminopropylamine, polyethylene oxide, tetrahydrofuran, and the like. However, it is not limited to this. In addition, the usage-amount of the said solvent has preferable 30-300 mass parts with respect to 100 mass parts of positive electrode active materials, and 50-200 mass parts is still more preferable.

  Usually, aluminum, stainless steel, nickel-plated steel or the like is used for the positive electrode current collector.

  In the non-aqueous electrolyte secondary battery of the present invention, a separator is used between the positive electrode and the negative electrode. As the separator, a commonly used polymer microporous film can be used without any particular limitation. Examples of the film include polyethylene, polypropylene, polyvinylidene fluoride, polyvinylidene chloride, polyacrylonitrile, polyacrylamide, polytetrafluoroethylene, polysulfone, polyethersulfone, polycarbonate, polyamide, polyimide, polyethylene oxide and polypropylene oxide. Films composed of ethers, various celluloses such as carboxymethylcellulose and hydroxypropylcellulose, polymer compounds mainly composed of poly (meth) acrylic acid and various esters thereof, derivatives thereof, copolymers and mixtures thereof. Etc.

  These films may be used alone, or may be used as a multilayer film by superimposing these films. Furthermore, various additives may be used for these films, and the kind and content thereof are not particularly limited. Among these films, a film made of polyethylene, polypropylene, polyvinylidene fluoride, or polysulfone is preferably used for the nonaqueous electrolyte secondary battery of the present invention. These films are microporous so that the electrolyte can penetrate and ions can easily pass therethrough. The microporosity method includes a phase separation method in which a polymer compound and a solvent solution are formed into a film while microphase separation is performed, and the solvent is extracted and removed to make it porous. The film is extruded and then heat treated, the crystals are arranged in one direction, and a “stretching method” or the like is performed by forming a gap between the crystals by stretching, and is appropriately selected depending on the film used.

  In the non-aqueous electrolyte secondary battery of the present invention, the electrode material, the non-aqueous electrolyte, and the separator include a phenol-based antioxidant, a phosphorus-based antioxidant, and a thioether-based antioxidant for the purpose of improving safety. A hindered amine compound or the like may be added.

  Examples of the phenolic antioxidant include 1,6-hexamethylenebis [(3-tert-butyl-5-methyl-4-hydroxyphenyl) propionic acid amide], 4,4′-thiobis (6-t -Butyl-m-cresol), 4,4'-butylidenebis (6-t-butyl-m-cresol), 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane 1,3,5-tris (2,6-dimethyl-3-hydroxy-4-tert-butylbenzyl) isocyanurate, 1,3,5-tris (3,5-di-tert-butyl-4-hydroxy Benzyl) isocyanurate, 1,3,5-tris (3,5-di-t-butyl-4-hydroxybenzyl) -2,4,6-trimethylbenzene, tetrakis [3- (3,5-di-t -Butyl- -Hydroxyphenyl) propionate methyl] methane, thiodiethylene glycol bis [(3,5-di-t-butyl-4-hydroxyphenyl) propionate], 1,6-hexamethylene bis [(3,5-di-t- Butyl-4-hydroxyphenyl) propionate], bis [3,3-bis (4-hydroxy-3-tert-butylphenyl) butyric acid] glycol ester, bis [2-tert-butyl-4-methyl-6- (2-Hydroxy-3-t-butyl-5-methylbenzyl) phenyl] terephthalate, 1,3,5-tris [(3,5-di-t-butyl-4-hydroxyphenyl) propionyloxyethyl] isocyanurate 3,9-bis [1,1-dimethyl-2-{(3-tert-butyl-4-hydroxy-5-methylphenyl ) Propionyloxy} ethyl] -2,4,8,10-tetraoxaspiro [5,5] undecane, triethylene glycol bis [(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate] and the like. When added to the electrode material, it is preferable to use 0.01 to 10 parts by mass, particularly 0.05 to 5 parts by mass with respect to 100 parts by mass of the electrode material.

Examples of the phosphorus antioxidant include trisnonylphenyl phosphite and tris [2-t-butyl-4- (3-t-butyl-4-hydroxy-5-methylphenylthio) -5-methylphenyl]. Phosphite, tridecyl phosphite, octyl diphenyl phosphite, di (decyl) monophenyl phosphite, di (tridecyl) pentaerythritol diphosphite, di (nonylphenyl) pentaerythritol diphosphite, bis (2,4-di -T-butylphenyl) pentaerythritol diphosphite, bis (2,6-di-t-butyl-4-methylphenyl) pentaerythritol diphosphite, bis (2,4,6-tri-t-butylphenyl) Pentaerythritol diphosphite, bis (2,4-dicumylphenyl) Pentaerythritol diphosphite, tetra (tridecyl) isopropylidene diphenol diphosphite, tetra (tridecyl) -4,4′-n-butylidenebis (2-t-butyl-5-methylphenol) diphosphite, hexa (tridecyl)- 1,1,3-tris (2-methyl-4-hydroxy-5-t-butylphenyl) butane triphosphite, tetrakis (2,4-di-t-butylphenyl) biphenylene diphosphonite, 9,10-dihydro -9-oxa-10-phosphaphenanthrene-10-oxide, 2,2'-methylenebis (4,6-t-butylphenyl) -2-ethylhexyl phosphite, 2,2'-methylenebis (4,6 -T-butylphenyl) -octadecyl phosphite, 2,2'-ethylidenebis ( , 6-di-t-butylphenyl) fluorophosphite, tris (2-[(2,4,8,10-tetrakis-t-butyldibenzo [d, f] [1,3,2] dioxaphosphine) Pin-6-yl) oxy] ethyl) amine, 2-ethyl-2-butylpropylene glycol and 2,4,6-tri-t-butylphenol phosphite.

  Examples of the thioether-based antioxidant include dialkylthiodipropionates such as dilauryl thiodipropionate, dimyristyl thiodipropionate, and distearyl thiodipropionate, and pentaerythritol tetra (β-alkylmercaptopropionate esters). Is mentioned.

  Examples of the hindered amine compound include 2,2,6,6-tetramethyl-4-piperidyl stearate, 1,2,2,6,6-pentamethyl-4-piperidyl stearate, 2,2,6,6. -Tetramethyl-4-piperidylbenzoate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, tetrakis (2,2,6,6-tetramethyl-4-piperidyl) -1,2, 3,4-butanetetracarboxylate, tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) -1,2,3,4-butanetetracarboxylate, bis (2,2,6,6) -Tetramethyl-4-piperidyl) -di (tridecyl) -1,2,3,4-butanetetracarboxylate, bis (1,2,2,6,6-pentamethyl-4-pi Lysyl) .di (tridecyl) -1,2,3,4-butanetetracarboxylate, bis (1,2,2,4,4-pentamethyl-4-piperidyl) -2-butyl-2- (3,5 -Di-t-butyl-4-hydroxybenzyl) malonate, 1- (2-hydroxyethyl) -2,2,6,6-tetramethyl-4-piperidinol / diethyl succinate polycondensate, 1,6 -Bis (2,2,6,6-tetramethyl-4-piperidylamino) hexane / 2,4-dichloro-6-morpholino-s-triazine polycondensate, 1,6-bis (2,2,6, 6-tetramethyl-4-piperidylamino) hexane / 2,4-dichloro-6-t-octylamino-s-triazine polycondensate, 1,5,8,12-tetrakis [2,4-bis (N- Butyl-N- (2,2,6 6-tetramethyl-4-piperidyl) amino) -s-triazin-6-yl] -1,5,8,12-tetraazadodecane, 1,5,8,12-tetrakis [2,4-bis (N -Butyl-N- (1,2,2,6,6-pentamethyl-4-piperidyl) amino) -s-triazin-6-yl] -1,5,8-12-tetraazadodecane, 1,6, 11-tris [2,4-bis (N-butyl-N- (2,2,6,6-tetramethyl-4-piperidyl) amino) -s-triazin-6-yl] aminoundecane, 1,6, Hindered amine compounds such as 11-tris [2,4-bis (N-butyl-N- (1,2,2,6,6-pentamethyl-4-piperidyl) amino) -s-triazin-6-yl] aminoundecane Is mentioned.

  The shape of the non-aqueous electrolyte secondary battery of the present invention having the above configuration is not particularly limited, and can be various shapes such as a coin shape, a cylindrical shape, and a square shape. FIG. 1 shows an example of a coin-type battery of the nonaqueous electrolyte secondary battery of the present invention, and FIGS. 2 and 3 show examples of a cylindrical battery, respectively.

  In the coin-type non-aqueous electrolyte secondary battery 10 shown in FIG. 1, 1 is a positive electrode capable of releasing lithium ions, 1a is a positive electrode current collector, and 2 is a carbonaceous material capable of inserting and extracting lithium ions released from the positive electrode. The negative electrode current collector, 2a is a negative electrode current collector, 3 is a non-aqueous electrolyte of the present invention, 4 is a stainless steel positive electrode case, 5 is a stainless steel negative electrode case, 6 is a polypropylene gasket, and 7 is a polyethylene separator. It is.

  Further, in the cylindrical non-aqueous electrolyte secondary battery 10 ′ shown in FIGS. 2 and 3, 11 is a negative electrode, 12 is a negative electrode assembly, 13 is a positive electrode, 14 is a positive electrode current collector, and 15 is a non-electrode of the present invention. Water electrolyte, 16 separator, 17 positive electrode terminal, 18 negative electrode terminal, 19 negative electrode plate, 20 negative electrode lead, 21 positive electrode plate, 22 positive electrode lead, 23 case, 24 insulating plate, 25 gasket , 26 are safety valves, and 27 is a PTC element.

  EXAMPLES Hereinafter, the present invention will be specifically described by way of examples, but these do not limit the scope of the present invention. In the examples, “parts” and “%” are based on mass unless otherwise specified.

Synthesis Example 1 Synthesis of Compound A1 A 1000 ml three-necked flask equipped with a reflux was charged with 37.0 g of 2-propinol (also referred to as propargyl alcohol), 72.9 g of triethylamine, and 210 g of ethyl acetate, and oxychlorinated in a nitrogen atmosphere. 30.8 g of phosphorus was dropped from the dropping funnel while cooling with ice. After the dropwise addition, the reaction was further completed at room temperature for 1 hour. After the reaction, the reaction solution was washed thoroughly with water and purified by distillation under reduced pressure to obtain 28.2 g (yield 66%) of compound A1 [tris (2-propynyl) phosphate]. Compound A1 is a compound in which R ¹ and R ² are hydrogen atoms and R ³ is 2-propynyl in general formula (1).

Synthesis Example 2 Synthesis of Compound A2 A 1000 ml three-necked flask equipped with a reflux was charged with 24.7 g of 2-propinol, 48.6 g of triethylamine, and 210 g of ethyl acetate, and 32.7 g of ethyl phosphorodichloridate under a nitrogen atmosphere. Was dropped from the dropping funnel while cooling with ice. After the dropwise addition, the reaction was further completed at room temperature for 1 hour. After the reaction, the reaction solution was washed thoroughly with water and purified by distillation under reduced pressure to obtain 27.7 g (yield 68%) of compound A2 [ethylbis (2-propynyl) phosphate]. Compound A2 is a compound in which R ¹ and R ² are hydrogen atoms and R ³ is ethyl in general formula (1).

[Synthesis Example 3] Synthesis of Compound A3 A 1000 ml three-necked flask equipped with a reflux was charged with 24.7 g of propargyl alcohol (propinol), 48.6 g of triethylamine and 210 g of ethyl acetate, and 2-chloroethyl phosphoryl dichloride under a nitrogen atmosphere. 39.6 g was dropped from the dropping funnel while cooling with ice. After the dropwise addition, the reaction was further completed at room temperature for 1 hour. After the reaction, the reaction solution was washed thoroughly with water and purified by distillation under reduced pressure to obtain 30.5 g (yield: 64%) of compound A3 [2-chloroethylbis (2-propynyl) phosphate]. Compound A3 is a compound in which R ¹ and R ² are hydrogen atoms and R ³ is 2-chloroethyl in general formula (1).

[Examples 1-31 and Comparative Examples 1-16]
In the examples and comparative examples, nonaqueous electrolyte secondary batteries (lithium secondary batteries) were produced according to the following production procedure.

<Production procedure>
a. Production of positive electrode [Production of positive electrode A]
85 parts by mass of LiCoO ₂ as a positive electrode active material, 10 parts by mass of acetylene black as a conductive material, and 5 parts by mass of polyvinylidene fluoride (PVDF) as a binder were mixed to obtain a positive electrode material. 100 parts by mass of this positive electrode material was dispersed in 140 parts by mass of N-methyl-2-pyrrolidone (NMP) to form a slurry. This slurry was applied to both surfaces of an aluminum positive electrode current collector, dried, and press-molded to obtain a positive electrode plate. Then, this positive electrode plate was cut into a predetermined size to produce a disc-shaped positive electrode A.

[Preparation of positive electrode B]
90 parts by mass of LiNiO ₂ as a positive electrode active material, 5 parts by mass of acetylene black as a conductive material, and 5 parts by mass of polyvinylidene fluoride (PVDF) as a binder were mixed to obtain a positive electrode material. 100 parts by mass of this positive electrode material was dispersed in 140 parts by mass of N-methyl-2-pyrrolidone (NMP) to form a slurry. This slurry was applied to both surfaces of an aluminum positive electrode current collector, dried, and press-molded to obtain a positive electrode plate. Thereafter, the positive electrode plate was cut into a predetermined size to produce a disc-shaped positive electrode B.

[Preparation of positive electrode C]
84 parts by mass of LiFePO ₄ as a positive electrode active material, 12 parts by mass of acetylene black as a conductive material, and 4 parts by mass of polyvinylidene fluoride (PVDF) as a binder were mixed to obtain a positive electrode material. 100 parts by mass of this positive electrode material was dispersed in 140 parts by mass of N-methyl-2-pyrrolidone (NMP) to form a slurry. This slurry was applied to both surfaces of an aluminum positive electrode current collector, dried, and press-molded to obtain a positive electrode plate. Then, this positive electrode plate was cut into a predetermined size to produce a disc-shaped positive electrode C.

b. Production of negative electrode [Production of negative electrode A]
97.0 parts by mass of artificial graphite as a negative electrode active material, 2.0 parts by mass of styrene butadiene rubber as a binder, and 1.0 part by mass of carboxymethyl cellulose as a thickener were mixed to obtain a negative electrode material. 100 parts by mass of this negative electrode material was dispersed in 120 parts by mass of water to form a slurry. This slurry was applied to both sides of a copper negative electrode current collector, dried and press-molded to obtain a negative electrode plate. Then, this negative electrode plate was cut into a predetermined size to produce a disc-shaped negative electrode A. The carboxymethylcellulose used is a sodium neutralized product having a degree of etherification of 0.9 and a 1% by weight aqueous solution having a viscosity of 1600 at 20 ° C.

[Production of Negative Electrode B]
97.0 parts by mass of artificial graphite as a negative electrode active material and 3.0 parts by mass of lithium polyacrylate as a binder / thickening agent were mixed to obtain a negative electrode material. 100 parts by mass of this negative electrode material was dispersed in 120 parts by mass of water to form a slurry. This slurry was applied to both sides of a copper negative electrode current collector, dried and press-molded to obtain a negative electrode plate. Then, this negative electrode plate was cut into a predetermined size to produce a disc-shaped negative electrode B. The lithium polyacrylate used is a lithium salt of polyacrylic acid having a mass average molecular weight of 100,000.

c. Preparation of non-aqueous electrolyte solution In a mixed solvent consisting of 30% by volume of ethylene carbonate, 40% by volume of ethyl methyl carbonate, 25% by volume of dimethyl carbonate and 5% by volume of propyl acetate, LiPF ₆ as an electrolyte salt at a concentration of 1 mol / L Dissolved. In this solution, an electrolyte additive (compounds A1 to A3, B1 to B3, C1 and C2, D1, and E1) is blended so as to have a concentration as shown in [Table 1] or [Table 2] below. Nonaqueous electrolytes of Examples 1 to 31 and Comparative Examples 1 to 16 were prepared. The numbers in parentheses in Table 1 represent the concentration (% by mass) in the non-aqueous electrolyte.

In the above [Table 1] and [Table 2], compounds other than the compounds A1 to A3 are as follows.
[Comparative Compound of Compounds A1 to A3]
Compound B1: Triethyl phosphate compound B2: Tribenzyl phosphate compound B3: Triallyl phosphate [compound of general formula (2)]
Compound C1: Dimethyldipropargylsilane [Compound of general formula (3)]
Compound C2: Tripropargyl borate [Compound of general formula (4)]
Compound D1: Trimethylsilyl acrylate [cyclic carbonate compound having an unsaturated group]
Compound E1: Vinylene carbonate

d. Assembling the Battery A microporous film made of polyethylene having a thickness of 25 μm was sandwiched between the obtained disc-shaped positive electrode A, B or C and the disc-shaped negative electrode A or B, and held in the case. Thereafter, the combinations of the nonaqueous electrolytes of Examples 1 to 31 or the nonaqueous electrolytes of Comparative Examples 1 to 16, the positive electrode A, B or C, and the negative electrode A or B are [Table 1] or [Table 2]. Thus, each non-aqueous electrolyte was poured into the case, and the case was sealed and sealed to produce a coin-type lithium secondary battery having a diameter of 20 mm and a thickness of 3.2 mm.

  Using the lithium secondary batteries containing the non-aqueous electrolytes of Examples 1 to 31 or Comparative Examples 1 to 16, initial characteristic tests and cycle characteristic tests were performed by the following test methods. In the initial characteristic test, the discharge capacity ratio (%) and the internal resistance ratio (%) were obtained. In the cycle characteristic test, the discharge capacity retention rate (%) and the internal resistance increase rate (%) were determined. These test results are shown in the above [Table 1] and [Table 2].

<Initial characteristic test method>
a. Method for measuring discharge capacity ratio A lithium secondary battery is placed in a constant temperature bath at 20 ° C., and charged at a constant current and a constant voltage up to 4.2 V with a charging current of 0.3 mA / cm ² (current value corresponding to 0.2 C). The operation of performing a constant current discharge to 3.0 V at a discharge current of 0.3 mA / cm ² (current value corresponding to 0.2 C) was performed five times. Thereafter, the battery was charged at a constant current and a constant voltage up to 4.2 V at a charging current of 0.3 mA / cm ² and discharged at a constant current of 3.0 mA at a discharge current of 0.3 mA / cm ² . The discharge capacity measured at the sixth time was defined as the initial discharge capacity of the battery, and the ratio of the initial discharge capacity when the discharge capacity ratio (%) was 100 as the initial discharge capacity of Example 1 as shown in the following formula. As sought.
Discharge capacity ratio = [(initial discharge capacity) / (initial discharge capacity in Example 1)] × 100

b. Measuring method of internal resistance ratio About lithium secondary battery after 6 cycles measurement, charge current 1.5mA / cm ² (current value equivalent to 1C), constant current constant voltage charge to 3.75V, AC impedance measuring device (IVIUM Using a TECHNOLOGIES product name: mobile potentiostat CompactStat, a frequency of 100 kHz to 0.02 Hz was scanned, and a Cole-Cole plot showing the imaginary part on the vertical axis and the real part on the horizontal axis was created. Subsequently, in this Cole-Cole plot, the arc part is fitted with a circle, and the larger value of the two points intersecting the real part of the circle is taken as the initial internal resistance of the battery, as shown in the following formula: The internal resistance ratio (%) was determined as the ratio of the initial internal resistance when the initial internal resistance of Example 1 was 100.
Internal resistance ratio (%) = “(initial internal resistance) / (initial internal resistance in Example 1)” × 100

<Cycle characteristic test method>
a. Method of measuring discharge capacity retention rate The battery after the initial characteristic test is placed in a thermostat at 60 ° C., and a charging current of 1.5 mA / cm ² (current value equivalent to 1 C, 1 C is a current that discharges the battery capacity in one hour. Value) at a constant current of up to 4.2 V and a constant current discharge of up to 3.0 V at a discharge current of 1.5 mA / cm ² was repeated 150 times. The discharge capacity at the 150th time is defined as the discharge capacity after the cycle test, and as shown in the following formula, the discharge capacity retention rate (%) is the discharge capacity after the cycle test when the initial discharge capacity of each battery is 100. Calculated as a percentage.
Discharge capacity retention rate (%) = [(discharge capacity after cycle test) / (initial discharge capacity)] × 100

b. Method for measuring rate of increase in internal resistance After the cycle test, the ambient temperature is returned to 20 ° C., and the internal resistance at 20 ° C. is measured in the same manner as the method for measuring the internal resistance ratio. The internal resistance increase rate (%) was determined as the rate of increase in internal resistance after the cycle test when the initial internal resistance of each battery was 100, as shown in the following formula.
Internal resistance increase rate (%) = “(internal resistance after cycle test−initial internal resistance) / (initial internal resistance)] × 100

  As is clear from the results of the above [Table 1] and [Table 2], the non-aqueous electrolyte secondary battery of the present invention comprises a non-aqueous electrolyte containing a phosphate ester compound to which an alkynyl group is bonded. Was excellent in terms of internal resistance and discharge capacity, and it was confirmed that excellent battery characteristics could be maintained even after a cycle test at 60 ° C.

  The non-aqueous electrolyte secondary battery of the present invention can maintain a small internal resistance and a high discharge capacity even in the case of long-term use and a large temperature change. Such non-aqueous electrolyte secondary batteries include video cameras, digital cameras, portable music players, sound recorders, portable DVD players, portable game machines, laptop computers, electronic dictionaries, electronic notebooks, electronic books, mobile phones, mobile TVs, electric motors. It can be used for various applications such as an assist bicycle, a battery car, and a hybrid car. Among them, it can be suitably used for a battery car, a hybrid car, and the like that may be used in a high temperature state.

DESCRIPTION OF SYMBOLS 1 Positive electrode 1a Positive electrode collector 2 Negative electrode 2a Negative electrode collector 3 Electrolyte 4 Positive electrode case 5 Negative electrode case 6 Gasket 7 Separator 10 Coin type nonaqueous electrolyte secondary battery 10 'Cylindrical type nonaqueous electrolyte secondary battery 11 Negative electrode 12 Negative electrode assembly 13 Positive electrode 14 Positive electrode assembly 15 Electrolyte 16 Separator 17 Positive electrode terminal 18 Negative electrode terminal 19 Negative electrode plate 20 Negative electrode lead 21 Positive electrode 22 Positive electrode lead 23 Case 24 Insulating plate 25 Gasket 26 Safety valve 27 PTC element

Claims (8)

Polyacrylic acid, polymethacrylic acid, acrylic acid / olefin copolymer, acrylic acid / maleic acid copolymer, methacrylic acid / olefin copolymer, methacrylic acid / maleic acid copolymer, fumaric acid / styrene copolymer, maleic acid / styrene copolymer, carboxymethylcellulose, Alginic acid or fumaric acid or maleic acid and C2-5 olefin, ethylene, propylene, 1-butene, 2-butene, isobutene, 1-propylene, 2-propylene, 1-propylene, 2-propylene or isopropylene In a non-aqueous electrolyte used for a secondary battery having a negative electrode containing a polymeric carboxylic acid compound selected from a copolymer with cyclopropylene and a crystalline carbon material as a negative electrode active material, the following general formula (1) In the table Nonaqueous electrolyte characterized by containing 0.001 to 5 wt% of unsaturated phosphoric acid ester compound.

(Wherein R ¹ and R ² each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R ³ represents methyl, ethyl, propyl, butyl, pentyl, 2-chlorobutyl, 2-propynyl, 3 -Represents chlorobutyl or 4-chlorobutyl ) Furthermore, 0.001-5 mass% of unsaturated boric acid ester compounds represented by the unsaturated silane compound represented by the following general formula (2) or the following general formula (3) are contained. Non-aqueous electrolyte.

(In the formula, R ⁴ and R ⁵ each independently represent a hydrogen atom or an alkyl group having 1 to 8 carbon atoms; R ⁶ and R ⁷ each independently represent an alkyl group having 1 to 8 carbon atoms; Represents an alkenyl group having -8 or an alkynyl group having 2 to 8 carbon atoms.)

(In the formula, R ⁸ and R ⁹ each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.) Furthermore, the non-aqueous electrolyte of Claim 1 or 2 containing 0.001-5 mass% of unsaturated carboxylic acid silyl ester compounds represented by following General formula (4).

(In the formula, R ¹⁰ represents an alkenyl group having 2 to 8 carbon atoms or an alkynyl group having 2 to 8 carbon atoms, and R ¹¹ , R ¹² and R ¹³ each independently have an ether group or a halogen atom. Represents a C1-C8 alkyl group or alkenyl group. Further, one or more compounds selected from the group consisting of a cyclic carbonate compound having an unsaturated group, a chain carbonate compound, an unsaturated diester compound, a halogenated cyclic carbonate compound, a cyclic sulfite compound, and a cyclic sulfate compound are added in an amount of 0.0. The nonaqueous electrolytic solution according to any one of claims 1 to 3, which contains 005 to 10% by mass .   The organic solvent used in the non-aqueous electrolyte is one or more solvents selected from the group consisting of cyclic carbonate compounds, cyclic ester compounds, sulfone or sulfoxide compounds and amide compounds, and chain carbonate compounds and chain ether compounds. The nonaqueous electrolytic solution according to any one of claims 1 to 4, which is a mixed solvent with one or more solvents selected from the group consisting of a cyclic ether compound and a saturated chain ester compound.   The nonaqueous electrolytic solution according to claim 5, which contains 0.5 to 30% by mass of the saturated chain ester compound. Polyacrylic acid, polymethacrylic acid, acrylic acid / olefin copolymer, acrylic acid / maleic acid copolymer, methacrylic acid / olefin copolymer, methacrylic acid / maleic acid copolymer, fumaric acid / styrene copolymer, maleic acid / styrene copolymer, carboxymethylcellulose, From copolymers of alginic acid or fumaric acid or maleic acid with C2-5 olefins, ethylene, propylene, 1-butene, 2-butene, isobutene, 1-propylene, 2-propylene, or isopropylene, cyclopropylene. A non-aqueous electrolyte solution having a negative electrode, a positive electrode, and a non-aqueous electrolyte solution according to any one of claims 1 to 6, comprising a selected polymer carboxylic acid compound and a crystalline carbon material as a negative electrode active material. Next battery.   The secondary battery having a non-aqueous electrolyte according to claim 7, wherein the positive electrode active material used for the positive electrode is a lithium compound containing iron or nickel.

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