JP5604162B2 - Non-aqueous electrolyte for secondary battery and non-aqueous electrolyte secondary battery using the electrolyte - Google Patents

Description

  The present invention relates to a non-aqueous electrolyte for a secondary battery 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.

  In non-aqueous electrolytes for secondary batteries used in non-aqueous electrolyte secondary batteries, lithium hexafluorophosphate or lithium tetrafluoroborate is often used as the electrolyte salt. In non-aqueous electrolyte secondary batteries using non-aqueous electrolytes containing these salts, the cause is pentafluoroline or trifluoroboron generated by thermal equilibrium reaction from hexafluorophosphate anion or tetrafluoroborate anion. A high temperature deterioration reaction occurs, and a decrease in electric capacity and an increase in internal resistance are inevitable due to high temperature storage or repeated charge / discharge. Since such a high temperature degradation reaction mainly occurs on the surface of the positive electrode or the negative electrode, the reaction is suppressed by adding an additive that protects the surface of the positive electrode or the negative electrode in the non-aqueous electrolyte. .

  Examples of the additive for protecting the negative electrode include 1,3-propane sultone (for example, see Patent Document 1), vinyl ethylene carbonate (for example, see Patent Document 2), and vinylene carbonate (for example, see Patent Document 3). ), 1,3-propane sultone, butane sultone (for example, see Patent Document 4), vinylene carbonate (for example, see Patent Document 5), vinyl ethylene carbonate (for example, see Patent Document 6), and the like are known. Of these, vinylene carbonate is widely used because of its great effect. When these negative electrode additives form a stable film called SEI (Solid Electrolyte Interface) on the surface of the negative electrode and this film covers the surface of the negative electrode, the reductive decomposition of the non-aqueous electrolyte is suppressed. It is considered. However, SEI produced by these additives cannot be said to have sufficient durability, and there has been a problem that it gradually collapses due to the produced pentafluoroline and trifluoroboron.

  On the other hand, as an additive for protecting the positive electrode, for example, disiloxane containing an unsaturated group such as a vinyl group (see, for example, Patent Document 7), an organic fluorosilane compound (for example, Patent Documents 8 and 9). For example). These additives for the positive electrode are thought to protect the positive electrode by adsorbing to the surface of the positive electrode and to suppress oxidative decomposition of the non-aqueous electrolyte, but at high temperatures, the adsorption and desorption to the electrode surface are repeated. For this reason, there is a problem that the protective effect is not sufficient when stored at a high temperature, and the electric capacity is decreased and the internal resistance is increased. For example, the higher the number of Si-F bonds in the molecule, the higher the reactivity and the easier the adsorption of the organic fluorosilane compound to the positive electrode surface. However, the conventionally known organic fluorosilane compound has a high temperature when the reactivity is high. There was a problem in protection performance due to poor stability. Moreover, although the organic fluorosilane compound which has a cycloalkyl group is also known, the effect as a non-aqueous electrolyte additive is not disclosed.

  On the other hand, lithium cobalt composite oxide is widely used as the positive electrode active material because a high voltage can be stably obtained. Since lithium cobalt complex oxide uses cobalt, which is a rare and expensive transition metal, positive electrode active materials containing cheaper transition metals such as manganese, nickel, and iron have been studied. A positive electrode having a positive electrode active material containing nickel or iron has a problem that a high-temperature deterioration reaction of a non-aqueous electrolyte for a battery tends to occur, and an additive capable of protecting such a positive electrode is demanded.

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 2002-134169 A JP 2004-171981 A JP 2007-141831 A

  Therefore, the object of the present invention is to maintain a small internal resistance and a high electric capacity even after high temperature storage, and even a positive electrode having a positive electrode active material containing nickel or iron has a high temperature of a non-aqueous electrolyte. An object of the present invention is to provide a non-aqueous electrolyte for a secondary battery in which a deterioration reaction hardly occurs and a non-aqueous electrolyte secondary battery using the non-aqueous electrolyte.

  As a result of intensive studies, the present inventors have found that the difluorosilane having a bulky cycloalkyl group and a straight chain alkyl group is excellent in the protection performance of the positive electrode, and is blended in the non-aqueous electrolyte solution to achieve the object. The present invention has been completed.

（式中、Ｒ¹は炭素数５〜８のシクロアルキル基を表わし、Ｒ²は炭素数１〜８のアルキル基を表わす。） That is, the present invention provides a non-aqueous electrolyte for a secondary battery containing an organic solvent and an electrolyte salt, containing a difluorosilane compound represented by the following general formula (1): A water electrolyte is provided.

(In the formula, R ¹ represents a cycloalkyl group having 5 to 8 carbon atoms, and R ² represents an alkyl group having 1 to 8 carbon atoms.)

  Moreover, this invention provides the nonaqueous electrolyte secondary battery which has a negative electrode, a positive electrode, and the nonaqueous electrolyte for secondary batteries of any one of Claims 1-6.

  According to the present invention, it is possible to maintain a small internal resistance and a high electric capacity in a long-term use. In particular, in a non-aqueous electrolyte secondary battery using a positive electrode having a positive electrode active material containing nickel or iron. It has become possible to greatly extend the service life.

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 nonaqueous electrolytic solution for a secondary battery of the present invention will be described in detail based on preferred embodiments.
The non-aqueous electrolyte for secondary batteries of the present invention is characterized in that it contains a difluorosilane compound represented by the general formula (1) having a bulky cycloalkyl group and a linear alkyl group.

In the general formula (1), R ¹ represents a cycloalkyl group having 5 to 8 carbon atoms. Examples of the cycloalkyl group having 5 to 8 carbon atoms include cyclopentyl, cyclohexyl, methylcyclopentyl, cycloheptyl, methylcyclohexyl, bicyclo [2,2,1] heptyl, cyclooctyl, dimethylcyclohexyl and the like. As R ¹ , cyclopentyl, cyclohexyl and cycloheptyl are preferred, cyclopentyl and cyclohexyl are more preferred, and cyclohexyl is most preferred because it has little adverse effect on lithium ion migration and good charge characteristics.

In the general formula (1), R ² represents an alkyl group having 1 to 8 carbon atoms. Examples of the alkyl group having 1 to 8 carbon atoms include linear alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, heptyl, octyl; isopropyl, isobutyl, isopentyl, neopentyl, 2-methylpentyl, 2-ethylhexyl, Examples include branched alkyl groups such as 2-butyl, 2-pentyl, 3-pentyl, 2-hexyl, 3-hexyl, 2-heptyl, 2-octyl, t-butyl, and t-pentyl. R ² is preferably a linear alkyl group because of high stability at high temperatures. Among them, an alkyl group having 1 to 4 carbon atoms is preferable because it has little adverse effect on the movement of lithium ions and good charging characteristics, methyl, ethyl, propyl and butyl are more preferable, methyl and ethyl are more preferable, methyl Is most preferred.

Among the difluorosilane compounds represented by the general formula (1), examples of the compound in which R ¹ is cyclopentyl include, for example, cyclopentyldifluoromethylsilane, cyclopentylethyldifluorosilane, cyclopentyldifluoropropylsilane, cyclopentyldifluoroisopropylsilane, and cyclopentylbutyl. Difluorosilane, cyclopentylisobutyldifluorosilane, cyclopentyl-2-butyldifluorosilane, cyclopentyl-t-butyldifluorosilane, cyclopentyldifluoropentylsilane, cyclopentyldifluoroisopentylsilane, cyclopentyldifluoro-2-pentylsilane, cyclopentyldifluoro-t-pentylsilane , Cyclopentyl difluorohexyl silane, cyclopentyl di Fluoro-2-hexylsilane, cyclopentyldifluoroheptylsilane, cyclopentyldifluoro-2-heptylsilane, cyclopentyldifluorooctylsilane, cyclopentyldifluoro-2-octylsilane, cyclopentyldifluoro-2-methylpentylsilane, cyclopentyldifluoro-2-ethylhexylsilane, etc. Is mentioned.

Among the difluorosilane compounds represented by the general formula (1), examples of the compound in which R ¹ is cyclohexyl include, for example, cyclohexyldifluoromethylsilane, cyclohexylethyldifluorosilane, cyclohexyldifluoropropylsilane, cyclohexyldifluoroisopropylsilane, and butylcyclohexyl. Difluorosilane, isobutylcyclohexyldifluorosilane, 2-butylcyclohexyldifluorosilane, t-butylcyclohexyldifluorosilane, cyclohexyldifluoropentylsilane, cyclohexyldifluoroisopentylsilane, cyclohexyldifluoro-2-pentylsilane, cyclohexyldifluoro-t-pentylsilane, cyclohexyl Difluorohexylsilane, cyclohexyldiflu Ro-2-hexylsilane, cyclohexyldifluoroheptylsilane, cyclohexyldifluoro-2-heptylsilane, cyclohexyldifluorooctylsilane, cyclohexyldifluoro-2-octylsilane, cyclohexyldifluoro-2-methylpentylsilane, cyclohexyldifluoro-2-ethylhexylsilane, Examples include cyclohexylcyclopentyldifluorosilane.

Among the difluorosilane compounds represented by the general formula (1), examples of the compound in which R ¹ is cycloheptyl include cycloheptyldifluoromethylsilane, cycloheptylethyldifluorosilane, cycloheptyldifluoropropylsilane, and cycloheptyldifluoro. Isopropylsilane, butylcycloheptyldifluorosilane, isobutylcycloheptyldifluorosilane, 2-butylcycloheptyldifluorosilane, t-butylcycloheptyldifluorosilane, cycloheptyldifluoropentylsilane, cycloheptyldifluoroisopentylsilane, cycloheptyldifluoro-2- Pentylsilane, cycloheptyldifluoro-t-pentylsilane, cycloheptyldifluorohexylsilane, cycloheptyldiflu Lo-2-hexylsilane, cycloheptyldifluoroheptylsilane, cycloheptyldifluoro-2-heptylsilane, cycloheptyldifluorooctylsilane, cycloheptyldifluoro-2-octylsilane, cycloheptyldifluoro-2-methylpentylsilane, cycloheptyldifluoro -2-ethylhexylsilane, cycloheptylcyclopentyldifluorosilane, and the like.

  In the non-aqueous electrolyte for a secondary battery of the present invention, when the content of the difluorosilane compound represented by the general formula (1) is too small, a sufficient effect cannot be exhibited, and when the content is too large, In addition to not being able to obtain an increase effect commensurate with the content, the internal resistance of the secondary battery may increase. Therefore, in the non-aqueous electrolyte for secondary battery of the present invention, it is represented by the general formula (1). The content of the difluorosilane compound is preferably 0.01 to 5% by mass, more preferably 0.03 to 3% by mass, and most preferably 0.05 to 2% by mass.

  As the organic solvent used in the non-aqueous electrolyte for secondary batteries of the present invention, those usually used for non-aqueous electrolyte for secondary batteries can be used singly or in combination of two or more. Examples of such organic solvents include saturated cyclic carbonate compounds, saturated cyclic ester compounds, sulfoxide compounds, sulfone compounds, amide compounds, saturated chain carbonate compounds, chain ether compounds, cyclic ether compounds, saturated chain ester compounds, and the like. It is done.

  Among the organic solvents described above, saturated cyclic carbonate compounds, saturated cyclic ester compounds, sulfoxide compounds, sulfone compounds and amide compounds have a high relative dielectric constant, and thus increase the dielectric constant of the non-aqueous electrolyte for secondary batteries. . Among these, a saturated cyclic carbonate compound is particularly preferable. Examples of such saturated cyclic carbonate compounds include ethylene carbonate, 1,2-propylene carbonate, 1,3-propylene carbonate, 1,2-butylene carbonate, 1,3-butylene carbonate, 1,1, -dimethylethylene carbonate. Etc. Examples of the saturated cyclic ester compound include γ-butyrolactone, γ-valerolactone, γ-caprolactone, δ-hexanolactone, and δ-octanolactone. Examples of the sulfoxide compound include dimethyl sulfoxide, diethyl sulfoxide, dipropyl sulfoxide, diphenyl sulfoxide, thiophene, and the like. Examples of the sulfone compound include dimethyl sulfone, diethyl sulfone, dipropyl sulfone, diphenyl sulfone, sulfolane (also referred to as tetramethylene sulfone), 3-methyl sulfolane, 3,4-dimethyl sulfolane, and 3,4-diphenylmethyl sulfolane. , Sulfolene, 3-methylsulfolene, 3-ethylsulfolene, 3-bromomethylsulfolene, etc. Among them, sulfolane and tetramethylsulfolane are preferable. Examples of the amide compound include N-methylpyrrolidone, dimethylformamide, dimethylacetamide and the like.

  Of the organic solvents described above, saturated chain carbonate compounds, chain ether compounds, cyclic ether compounds, and saturated chain ester compounds can reduce the viscosity of the non-aqueous electrolyte for secondary batteries, and electrolyte ions The battery characteristics such as the output density can be made excellent. Moreover, since it is low-viscosity, the performance of the non-aqueous electrolyte for secondary batteries at low temperatures can be enhanced. Among these, a saturated chain carbonate compound is preferable. Examples of such saturated chain carbonate compounds include dimethyl carbonate (DMC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), ethyl butyl carbonate, methyl-t-butyl carbonate, diisopropyl carbonate, and t-butyl propyl carbonate. Etc. Examples of the chain ether compound or the cyclic ether compound include dimethoxyethane (DME), ethoxymethoxyethane, diethoxyethane, tetrahydrofuran, dioxolane, 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, Examples include diethylene glycol bis (trifluoroethyl) ether, and among these, dioxolane is preferable.

  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 preferable, and specific compounds include, for example, methyl formate, ethyl formate, methyl acetate, 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. Among these, methyl formate, ethyl formate, methyl acetate, ethyl acetate, propyl acetate, isobutyl acetate, butyl acetate ,Professional Propionic acid methyl and ethyl propionate are preferred.

The organic solvent used in the non-aqueous electrolyte for a secondary battery of the present invention is one or more organic compounds selected from the group consisting of the saturated cyclic carbonate compound, saturated cyclic ester compound, sulfoxide compound, sulfone compound and amide compound. A solvent (referred to as solvent A), and one or more organic solvents (referred to as solvent B) selected from the group consisting of the saturated chain carbonate compound, the chain ether compound, the cyclic ether compound and the saturated chain ester compound, In addition to being excellent in cycle characteristics, the non-aqueous electrolyte for secondary batteries is balanced in terms of the viscosity of the non-aqueous electrolyte for secondary batteries and the electric capacity and output of the resulting battery. Preferably, it is a mixture using a saturated cyclic carbonate compound as the solvent A and a saturated chain carbonate compound as the solvent B. Rukoto is more preferable. When the organic solvent used in the non-aqueous electrolyte for a secondary battery of the present invention is a mixture of the solvent A and the solvent B, the mixing ratio (mass basis) is preferably 1:10 to 10: 1. 3: 10-10: 3 is more preferable.

  The non-aqueous electrolyte for secondary batteries may suddenly deteriorate in battery characteristics at low temperatures. For the purpose of improving such deterioration in battery characteristics at low temperatures, the non-aqueous electrolyte for secondary batteries of the present invention is used. The organic solvent preferably contains the saturated chain ester compound as a part of the organic solvent. In particular, the organic solvent is a mixture of the saturated cyclic carbonate compound, the saturated chain carbonate compound, and the saturated chain ester compound. In this case, the deterioration of battery characteristics at low temperatures can be greatly improved. In the non-aqueous electrolyte for a secondary battery of the present invention, the content of the saturated chain ester compound is preferably 0.5 to 30% by mass in the organic solvent, and is 1 to 10% by mass. Is more preferable.

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

Examples of the electrolyte salt used in the non-aqueous electrolyte for a secondary battery of the present invention include conventionally known electrolyte salts. 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 , LiBF ₂ (C ₂ O ₄ ), LiSbF ₆ , LiSiF ₅ , Examples include LiAlF ₄ , LiSCN, LiClO ₄ , LiCl, LiF, 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, and LiC (CF ₃ SO _{2) 3} and derivatives LiCF ₃ SO _3, and LiC (CF ₃ SO _{2) 3} It is preferable because excellent electrical characteristic use at least one member selected from the group consisting of derivatives.

  The electrolyte salt is added to the organic solvent so that the concentration in the non-aqueous electrolyte for secondary battery of the present invention is 0.1 to 3.0 mol / L, particularly 0.5 to 2.0 mol / L. It is preferable to dissolve. If the concentration of the electrolyte salt is less than 0.1 mol / L, a sufficient current density may not be obtained. If the concentration is more than 3.0 mol / L, the stability of the non-aqueous electrolyte for secondary batteries may be impaired. There is.

  The non-aqueous electrolyte for a secondary battery of the present invention is further represented by the following general formula (2) because an excellent synergistic effect with the difluorosilane compound represented by the general formula (1) is obtained. It is preferable to contain an unsaturated phosphate ester compound or an unsaturated phosphate ester compound represented by the following general formula (3).

（式中、Ｒ³及びＲ⁴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、Ｒ⁵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。）

(Wherein R ³ and R ⁴ each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R ⁵ 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.)

（式中、Ｒ⁶及びＲ⁷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、Ｒ⁸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し、ｍは１又は２の数を表わす。）

(Wherein R ⁶ and R ⁷ each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R ⁸ represents an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, carbon A alkynyl group having 2 to 8 carbon atoms or a halogenated alkyl group having 1 to 8 carbon atoms, and m represents a number of 1 or 2.

In the general formula (2), R ³ and R ⁴ 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 the alkyl groups exemplified in the description of R ^{2 in} the general formula (1). R ³ and R ⁴ 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 the charging characteristics are good. .

In the general formula (2), R ⁵ 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 in the description of R ^{2 in} the general formula (1). 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. As R ⁵ , since the internal resistance of the nonaqueous electrolyte secondary battery is reduced, methyl, ethyl, propyl, isopropyl, butyl, pentyl, 2-propynyl, 3-chloropropyl, 3-chlorobutyl, and 4-chlorobutyl are included. Preferably, methyl, ethyl, propyl and 2-propynyl are more preferable, and ethyl and 2-propynyl are most preferable.

Of the unsaturated phosphate compounds represented by the general formula (2), examples of the compound in which R ³ and R ⁴ 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. .

Of the unsaturated phosphate ester compounds represented by the general formula (2), examples of the compound in which R ³ is methyl and R ⁴ is a hydrogen atom include, for example, methylbis (1-methyl-2-propynyl) phosphate , Ethylbis (1-methyl-2-propynyl) phosphate, propylbis (1-methyl-2-propynyl) phosphate, butylbis (1-methyl-2-propynyl) phosphate, pentylbis (1-methyl-2-propynyl) ) Phosphate, allyl bis (1-methyl-2-propynyl) phosphate, 2-propynyl bis (1-methyl-2-propynyl) phosphate, tris (1-methyl-1-methyl-2-propynyl) phosphate, 2-chloroethylbis (1-methyl-2-propynyl) phosphate, 2,2,2- Examples thereof include trifluoroethyl bis (1-methyl-2-propynyl) phosphate, 2,2,2-trichloroethyl bis (1-methyl-2-propynyl) phosphate, and the like.

Among the unsaturated phosphate compounds represented by the general formula (2), examples of the compound in which R ³ and R ⁴ are methyl include, for example, methyl bis (1,1-dimethyl-2-propynyl) phosphate, ethyl bis (1,1-dimethyl-2-propynyl) phosphate, propylbis (1,1-dimethyl-2-propynyl) phosphate, butylbis (1,1-dimethyl-2-propynyl) phosphate, pentylbis (1,1 -Dimethyl-2-propynyl) phosphate, allylbis (1,1-dimethyl-2-propynyl) phosphate, 2-propynylbis (1,1-dimethyl-2-propynyl) phosphate, tris (1,1-dimethyl) -2-propynyl) phosphate, 2-chloroethylbis (1,1-dimethyl-2-propynyl) ) Phosphate, 2,2,2-trifluoroethylbis (1,1-dimethyl-2-propynyl) phosphate, 2,2,2-trichloroethylbis (1,1-dimethyl-2-propynyl) phosphate Etc.

  Examples of the unsaturated phosphate compound represented by the general formula (2) 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 and 2-chloroethylbis (2-propynyl) phosphate are preferred, ethylbis (2-propynyl) phosphate, propylbis More preferred are (2-propynyl) phosphate, butyl bis (2-propynyl) phosphate and tris (2-propynyl) phosphate, and ethyl bis (2-propynyl) phosphate and tris (2-propynyl) phosphate. The most preferred.

In the general formula (3), R ⁶ and R ⁷ 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 the alkyl groups exemplified in the description of R ^{2 in} the general formula (1). R ⁶ and R ⁷ are preferably a hydrogen atom, methyl, ethyl, and propyl, more preferably a hydrogen atom and methyl, and most preferably a hydrogen atom, since there is little adverse effect on the movement of lithium ions and charging characteristics are good. .

In the general formula (3), R ⁸ 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 in the description of R ^{2 in} the general formula (1). Examples of the alkenyl group having 2 to 8 carbon atoms, the alkynyl group having 2 to 8 carbon atoms, and the halogenated alkyl group having 1 to 8 carbon atoms include 2 carbon atoms exemplified in the description of R ^{5 in} the general formula (2). -8 alkenyl group, C2-C8 alkynyl group, or C1-C8 halogenated alkyl group is mentioned. As R ⁵ , since the internal resistance of the nonaqueous electrolyte secondary battery is reduced, methyl, ethyl, propyl, isopropyl, butyl, pentyl, 2-propynyl, 3-chloropropyl, 3-chlorobutyl, and 4-chlorobutyl are included. Preferably, methyl, ethyl, propyl and 2-propynyl are more preferred, and methyl and ethyl are most preferred.

  In the general formula (3), m represents a number of 1 or 2. M is preferably 2 because the phosphoric acid ester reaction from the alkyne diol as the raw material is easy.

  Among the unsaturated phosphoric acid ester compounds represented by the general formula (3), as the compound where m is 1, for example, 2-butyne-1,4-diol tetramethyldiphosphate, 2-butyne-1, 4-diol tetraethyl diphosphate, 2-butyne-1,4-diol tetrapropyl diphosphate, 2-butyne-1,4-diol tetraisopropyl diphosphate, 2-butyne-1,4-diol tetrabutyl di Phosphate, 2-butyne-1,4-diol tetrapentyl diphosphate, 2-butyne-1,4-diol tetrakis (2-propynyl) diphosphate, 2-butyne-1,4-diol tetrakis (3- Chloropropyl) diphosphate, 2-butyne-1,4-dioltetrakis (3-chlorobutyl) diphosphate And 2-butyne-1,4-dioltetrakis (4-chlorobutyl) diphosphate, among which 2-butyne-1,4-dioltetramethyldiphosphate, 2-butyne-1, 4-Dioltetraethyldiphosphate, 2-butyne-1,4-dioltetrapropyldiphosphate, and 2-butyne-1,4-dioltetrakis (2-propynyl) diphosphate are preferred, and 2-butyne-1 , 4-diol tetramethyldiphosphate and 2-butyne-1,4-dioltetrakis (2-propynyl) diphosphate are more preferred.

  Moreover, as a compound whose m is 2 among the unsaturated phosphate ester compounds represented by the general formula (3), for example, 2,4-hexadiyne-1,6-dioltetramethyldiphosphate, 2, 4-hexadiyne-1,6-diol tetraethyl diphosphate, 2,4-hexadiyne-1,6-diol tetrapropyl diphosphate, 2,4-hexadiyne-1,6-diol tetraisopropyl diphosphate, 2, 4-hexadiyne-1,6-dioltetrabutyldiphosphate, 2,4-hexadiyne-1,6-dioltetrapentyldiphosphate, 2,4-hexadiyne-1,6-dioltetrakis (2-propynyl) di Phosphate, 2,4-hexadiyne-1,6-dioltetrakis (3-chloropropyl) Diphosphate, 2,4-hexadiyne-1,6-dioltetrakis (3-chlorobutyl) diphosphate, 2,4-hexadiyne-1,6-dioltetrakis (4-chlorobutyl) diphosphate, and the like. Among these, 2,4-hexadiyne-1,6-diol tetramethyl diphosphate, 2,4-hexadiyne-1,6-diol tetraethyl diphosphate, 2,4-hexadiyne-1,6-diol tetrapropyl Diphosphate and 2,4-hexadiyne-1,6-dioltetrakis (2-propynyl) diphosphate are preferred, 2,4-hexadiyne-1,6-dioltetramethyldiphosphate, and 2,4- Hexadiyne-1,6-diol tetrakis (2-propynyl) diphosphate A further preferred.

  The unsaturated phosphate ester compound represented by the general formula (2) and the unsaturated phosphate ester compound represented by the general formula (3) may be used alone or in combination of two or more. However, when only one kind is used, the synergistic effect with the difluorosilane compound represented by the general formula (1) is large, so that the problem represented by the general formula (2) It is preferable to use a saturated phosphate ester compound.

  In the non-aqueous electrolyte for a secondary battery of the present invention, the content of the unsaturated phosphate compound represented by the general formula (2) and the unsaturated phosphate compound represented by the general formula (3) is However, if the amount is too small, sufficient effects cannot be exhibited.If the amount is too large, not only an increase effect corresponding to the content cannot be obtained, but on the contrary, the characteristics of the non-aqueous electrolyte for secondary batteries may be adversely affected. Therefore, the content of the unsaturated phosphate compound is preferably 0.01 to 5% by mass, more preferably 0.03 to 4% by mass in the non-aqueous electrolyte for secondary battery of the present invention. 0.05-3 mass% is the most preferable. Moreover, the ratio of these unsaturated phosphate ester compounds with respect to the difluorosilane compound represented by the said General formula (1) is a mass ratio, and it is preferable that it is 0.01-100, and it is 0.05-20. More preferably, it is 0.2-10.

  The non-aqueous electrolyte for a secondary battery according to the present invention can suppress an increase in internal resistance due to accumulation of decomposition products on the surface of the positive electrode. Further, a sulfite compound, a sulfonate compound, an imide salt of an alkali metal, other It is preferable to contain at least one compound selected from the group consisting of a fluorosilane compound and an organic disilane or an organic disiloxane compound (hereinafter sometimes referred to as component (E)).

  Examples of the sulfite compound include aliphatic chain sulfite compounds such as dimethyl sulfinate and diethyl sulfinate; ethylene sulfinate, 1,2-propylene sulfinate, and 1,3-propylene sulfinate. Cyclic sulfite compounds such as 1,2-butylenesulfinate, 1,3-butylenesulfinate, 1,4-butylenesulfinate, 2,3-butylenesulfinate, etc., among these A cyclic sulfite compound is preferred, and ethylene sulfinate is more preferred. The said sulfite ester compound may use only 1 type, and may be used in combination of 2 or more type.

  Examples of the sulfonic acid ester compound include methanesulfonic acid methyl ester and methanesulfonic acid ethyl ester aliphatic chain monosulfonic acid ester compound; 1,3-propane sultone, 1,3-butane sultone, 1,4-butane sultone. 2,4-butane sultone, 1,1,1-trifluoro-2,4-butane sultone, 4,4,4-trifluoro-1,3-butane sultone, 1,3-propene sultone, 1,4-butylene sultone, etc. Cyclic monosulfonic acid ester compounds; cyclic disulfonic acid ester compounds such as methylenemethane disulfonate (compound represented by the following formula (4)), ethylenemethane disulfonate (compound represented by the following formula (5)), and the like. Among these, cyclic monosulfonic acid ester compounds and cyclic Sulfonic acid ester compounds are preferred, more preferably a cyclic mono-sulfonate compound, 1,3-propane sultone is most preferred. The said sulfonic acid ester compound may use only 1 type, and may be used in combination of 2 or more type.

Examples of the alkali metal imide salt include alkali metal fluoroalkylsulfonylimide salts, and among them, lithium fluoroalkylsulfonylimide salts are preferred. Specifically, bis (trifluoromethanesulfonyl) imide lithium [ Li (CF ₃ SO ₂ ) ₂ N], bis (pentafluoroethanesulfonyl) imide lithium [Li (C ₂ F ₅ SO ₂ ) ₂ N] and the like, among these, bis (trifluoromethanesulfonyl) imide lithium Is preferred. The alkali metal imide salt may be used alone or in combination of two or more.

  In the present invention, the other fluorosilane compound refers to a compound having at least one Si-F bond in the molecule and other than the difluorosilane compound represented by the general formula (1). Examples of such other fluorosilane compounds include compounds represented by the following general formula (6).

（式中、Ｒ⁹及びＲ¹⁰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、炭素数２〜８のアルキニル基、炭素数１〜８のハロゲン化アルキル基、ハロゲン原子を有してもよい炭素数６〜１８のアリール基、炭素数７〜１８のアラルキル基、炭素数５〜８のシクロアルキル基又は炭素数５〜８のシクロアルケニル基を表わし、Ｘはフッ素原子、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、炭素数１〜８のハロゲン化アルキル基、ハロゲン原子を有してもよい炭素数６〜１８のアリール基又は炭素数７〜１８のアラルキル基、下記一般式（７）表される基又は下記一般式（８）表される基を表わす。但し、Ｒ⁹及びＲ¹⁰のどちらか一方が炭素数１〜８のアルキル基であり、他方が炭素数５〜８のシクロアルキル基である場合は、Ｘはフッ素原子ではない。）

Wherein R ⁹ and R ¹⁰ are each independently 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 an alkyl halide having 1 to 8 carbon atoms. Group, an aryl group having 6 to 18 carbon atoms which may have a halogen atom, an aralkyl group having 7 to 18 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms or a cycloalkenyl group having 5 to 8 carbon atoms, X may have a fluorine atom, 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, a halogenated alkyl group having 1 to 8 carbon atoms, or a halogen atom. A good aryl group having 6 to 18 carbon atoms or an aralkyl group having 7 to 18 carbon atoms, a group represented by the following general formula (7), or a group represented by the following general formula (8), provided that R ⁹ and R ¹⁰ One of these is an alkyl group having 1 to 8 carbon atoms, and the other X is not a fluorine atom when is a cycloalkyl group having 5 to 8 carbon atoms.)

（式中、Ｒ⁹及びＲ¹⁰は前記一般式（６）と同義であり、Ｒ¹¹は炭素数１〜１５の２価の炭化水素基を表わす。）

(In the formula, R ⁹ and R ¹⁰ are as defined in the general formula (6), and R ¹¹ represents a divalent hydrocarbon group having 1 to 15 carbon atoms.)

（式中、Ｒ¹²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、炭素数１〜８のハロゲン化アルキル基、ハロゲン原子を有してもよい炭素数６〜１８のアリール基又は炭素数７〜１８のアラルキル基を表わし、Ｒ¹³は炭素数１〜１５の２価の炭化水素基を表わし、Ｙは酸素原子、−Ｃ（＝Ｏ）−Ｏ−基又はＯ−Ｃ（＝Ｏ）−基を表わす。）

(In the formula, R ¹² has 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, a halogenated alkyl group having 1 to 8 carbon atoms, or a halogen atom. An aryl group having 6 to 18 carbon atoms or an aralkyl group having 7 to 18 carbon atoms, R ¹³ represents a divalent hydrocarbon group having 1 to 15 carbon atoms, Y is an oxygen atom, and —C (= O) represents an —O— group or an O—C (═O) — group.

In the general formula (6), R ⁹ and R ¹⁰ are each independently 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 1 to 8 carbon atoms. A halogenated alkyl group, an aryl group having 6 to 18 carbon atoms which may have a halogen atom, an aralkyl group having 7 to 18 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms or a cyclohexane having 5 to 8 carbon atoms. Represents an alkenyl group. Examples of the alkyl group having 1 to 8 carbon atoms include the alkyl groups exemplified in the description of R ^{2 in} the general formula (1). Examples of the cycloalkyl group having 5 to 8 carbon atoms include those represented by the general formula (1). cycloalkyl groups exemplified in the description of R ¹ can be mentioned. Examples of the alkenyl group having 2 to 8 carbon atoms, the alkynyl group having 2 to 8 carbon atoms, and the halogenated alkyl group having 1 to 8 carbon atoms include the alkenyl groups and alkynyl groups exemplified in the description of R ^{5 in} the general formula (2). And halogenated alkyl groups.

  Examples of the C5-C8 cycloalkenyl group include cyclopentenyl, cyclohexenyl, cycloheptenyl, cyclooctenyl and the like.

  Examples of the aryl group having 6 to 18 carbon atoms which may have a halogen atom include phenyl, methylphenyl, dimethylphenyl, ethylphenyl, trimethylphenyl, propylphenyl, isopropylphenyl, butylphenyl, t-butylphenyl, and pentyl. Phenyl, t-pentylphenyl, hexylphenyl, heptylphenyl, octylphenyl, nonylphenyl, decylphenyl, undecylphenyl, dodecylphenyl, phenylphenyl, benzylphenyl, styrenated phenyl, 4- (1-methyl-1-phenylethyl) ) Phenyl (also referred to as p-cumylphenyl), dinonylphenyl, α-naphthyl, β-naphthyl, 2-fluorophenyl, 3-fluorophenyl, 4-fluorophenyl, 2,4-difluorophenyl, 3,5 Difluorophenyl, 2,6-difluorophenyl, 2,3-difluorophenyl, 4,5-difluorophenyl, 2,4,6-trifluorophenyl, 2,3,4-trifluorophenyl, tetrafluorophenyl, etc. It is done.

  Examples of the aralkyl group having 7 to 18 carbon atoms include benzyl, 2-phenylethyl, 2-phenyl-2-propyl, 3-phenylpropyl, diphenylmethyl and the like.

As R ⁹ and R ¹⁰ , it is preferable that at least one of R ⁹ and R ¹⁰ is methyl or ethyl, and at least one is methyl because the internal resistance of the nonaqueous electrolyte secondary battery of the present invention is small. More preferably, both are most preferably methyl.

In the general formula (6), X is a fluorine atom, 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 an alkyl halide having 1 to 8 carbon atoms. Group, an aryl group having 6 to 18 carbon atoms which may have a halogen atom, an aralkyl group having 7 to 18 carbon atoms, a group represented by the general formula (7) or the general formula (8) In the case where one of R ⁹ and R ¹⁰ is an alkyl group having 1 to 8 carbon atoms and the other is a cycloalkyl group having 5 to 8 carbon atoms, X is not a fluorine atom. 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, a halogenated alkyl group having 1 to 8 carbon atoms, and 6 to 6 carbon atoms which may have a halogen atom As the aryl group having 18 and the aralkyl group having 7 to 18 carbon atoms, the alkyl group, alkenyl group, alkynyl group, halogenated alkyl group, and aryl group optionally having a halogen atom exemplified in the description of R ⁹ and R ¹⁰ And an aralkyl group. X is preferably an alkyl group having 1 to 8 carbon atoms and a group represented by the general formula (7), more preferably an alkyl group having 1 or 2 carbon atoms and a group represented by the general formula (7). The group represented by the general formula (7) is most preferable.

In Formula (7), R ⁹ and R ¹⁰ are as defined in the general formula (6), R ¹¹ represents a divalent hydrocarbon group having 1 to 15 carbon atoms. Examples of the divalent hydrocarbon group having 1 to 15 carbon atoms include methanediyl (also referred to as methylene), 1,2-ethanediyl (also referred to as ethylene), 1,3-propanediyl (also referred to as trimethylene), 1,4 -Butanediyl (also called tetramethylene), 1,5-pentanediyl, 1,6-hexanediyl (also called hexamethylene), 1,7-heptanediyl, 1,8-octanediyl, 2-methyl-1,4-butanediyl 1,2-ethenediyl (also referred to as ethenylene or vinylene), 2-butene-1,4-diyl, 1,2-dimethyl-1,2-ethenediyl, 1,2-ethynediyl (also referred to as ethynylene), 1,4 -Cyclohexanediyl, 1,2-phenylene, 1,4-phenylene, (1,1'-biphenyl) -4,4'-diyl, etc. . As R ¹¹ , since the internal resistance of the nonaqueous electrolyte secondary battery of the present invention is reduced, 1,2-ethanediyl, 1,3-propanediyl, 1,4-butanediyl, 1,5-pentanediyl, 1,6-hexanediyl, 1,7-heptanediyl, 1,8-octanediyl, 2-methyl-1,4-butanediyl, 1,2-ethynediyl and 1,2-phenylene are preferred, 1,2-ethanediyl, 1,3-propanediyl and 1,4-butanediyl are more preferred, and 1,2-ethanediyl is most preferred.

In the general formula (8), R ¹² 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, a halogenated alkyl group having 1 to 8 carbon atoms, a halogen atom An aryl group having 6 to 18 carbon atoms or an aralkyl group having 7 to 18 carbon atoms which may have an atom is represented. 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, a halogenated alkyl group having 1 to 8 carbon atoms, and 6 to 6 carbon atoms which may have a halogen atom As the aryl group having 18 and the aralkyl group having 7 to 18 carbon atoms, the alkyl group, alkenyl group, alkynyl group, halogenated alkyl group, and aryl group optionally having a halogen atom exemplified in the description of R ⁹ and R ¹⁰ And an aralkyl group. R ¹² is preferably an alkyl group having 1 to 8 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms, and 1 carbon atom because the internal resistance of the non-aqueous electrolyte secondary battery of the present invention is small. Or the alkyl group of 2 is the most preferable.

In the general formula (8), R ¹³ represents a divalent hydrocarbon group having 1 to 15 carbon atoms, for example, a divalent hydrocarbon group exemplified 1 to 15 carbon atoms in the description of R ¹¹ . As R ¹³ , since the internal resistance of the nonaqueous electrolyte secondary battery of the present invention is reduced, 1,2-ethanediyl, 1,3-propanediyl, 1,4-butanediyl, 1,5-pentanediyl, 1,6-hexanediyl, 1,7-heptanediyl, 1,8-octanediyl, 2-methyl-1,4-butanediyl, 1,2-ethynediyl and 1,2-phenylene are preferred, 1,2-ethanediyl, 1,3-propanediyl and 1,4-butanediyl are more preferred, and 1,2-ethanediyl is most preferred.

  In the general formula (8), Y represents an oxygen atom, —C (═O) —O— group or O—C (═O) — group.

  Among the compounds represented by the general formula (6) in which X is a fluorine atom, specific examples of preferable compounds include, for example, butylmethyldifluorosilane, isobutylmethyldifluorosilane, pentylmethyldifluorosilane, hexylmethyldifluorosilane, Examples include heptylmethyldifluorosilane, octylmethyldifluorosilane, dicyclopentyldifluorosilane, and dicyclohexyldifluorosilane.

  Among the compounds represented by the general formula (6) in which X is an alkyl group having 1 to 8 carbon atoms, specific examples of preferable compounds include trimethylfluorosilane, ethyldimethylfluorosilane, propyldimethylfluorosilane, Isopropyldimethylfluorosilane, butyldimethylfluorosilane, sec-butyldimethylfluorosilane, t-butyldimethylfluorosilane, pentyldimethylfluorosilane, hexyldimethylfluorosilane, heptyldimethylfluorosilane, octyldimethylfluorosilane, 2-ethylhexyldimethylfluorosilane , Trifluoromethyldimethylfluorosilane, tetrafluoroethyldimethylfluorosilane, heptafluoropropyldimethylfluorosilane, 2,2,2-trifluoroethyl Methylfluorosilane, vinyldimethylfluorosilane, allyldimethylfluorosilane, 1-propenyldimethylfluorosilane, isopropenyldimethylfluorosilane, 2-butenyldimethylfluorosilane, 1,3-butadienyldimethylfluorosilane, 2-pentenyldimethyl Fluorosilane, 2-octenyldimethylfluorosilane, ethynyldimethylfluorosilane, 1-propynyldimethylfluorosilane, 2-propynyldimethylfluorosilane, 1-butynyldimethylfluorosilane, 2-butynyldimethylfluorosilane, 3-butynyl Dimethylfluorosilane, phenyldimethylfluorosilane, 2-fluorophenyldimethylfluorosilane, 3-fluorophenyldimethylfluorosilane, 4-fluoropheny Dimethylfluorosilane, 2,4-difluorophenyldimethylfluorosilane, 3,5-difluorophenyldimethylfluorosilane, 2,6-difluorophenyldimethylfluorosilane, 2,3-difluorophenyldimethylfluorosilane, 4,5-difluorophenyl Dimethylfluorosilane, 2,4,6-trifluorophenyldimethylfluorosilane, 2,3,4-trifluorophenyldimethylfluorosilane, tetrafluorophenyldimethylfluorosilane, 2-methylphenyldimethylfluorosilane, 3-methylphenyldimethyl Examples include fluorosilane, 4-methylphenyldimethylfluorosilane, 2,4-dimethylphenyldimethylfluorosilane, 3,5-dimethylphenyldimethylfluorosilane, and the like.

  Moreover, as a specific example of a preferable compound among the compounds represented by the said General formula (6) whose X is group represented by the said General formula (7), a 1, 2- di (dimethylfluoro) is mentioned, for example. Silyl) ethane, 1,2-di (diethylfluorosilyl) ethane, 1,2-di (dipropylfluorosilyl) ethane, 1,2-di (dibutylfluorosilyl) ethane, 1,3-di (dimethylfluorosilyl) ) Propane, 1,2-di (diethylfluorosilyl) propane, 1,3-di (dipropylfluorosilyl) propane, 1,3-di (dibutylfluorosilyl) propane, 1,4-di (dimethylfluorosilyl) Butane, 1,4-di (diethylfluorosilyl) butane, 1,4-di (dipropylfluorosilyl) butane, 1,4-di (dibutylfluorosilyl) butane 1,5-di (dimethylfluorosilyl) pentane, 1,5-di (diethylfluorosilyl) pentane, 1,5-di (dipropylfluorosilyl) pentane, 1,5-di (dibutylfluorosilyl) pentane, , 6-di (dimethylfluorosilyl) hexane, 1,6-di (diethylfluorosilyl) hexane, 1,6-di (dipropylfluorosilyl) hexane, 1,6-di (dibutylfluorosilyl) hexane, 1, 7-di (dimethylfluorosilyl) heptane, 1,7-di (diethylfluorosilyl) heptane, 1,7-di (dipropylfluorosilyl) heptane, 1,7-di (dibutylfluorosilyl) heptane, 1,8 -Di (dimethylfluorosilyl) octane, 1,8-di (diethylfluorosilyl) octane, 1,8-di (di (Lopylfluorosilyl) octane, 1,8-di (dibutylfluorosilyl) octane, 1,4-di (dimethylfluorosilyl) -2-methylbutane, 1,4-di (diethylfluorosilyl) -2-methylbutane, , 4-di (dipropylfluorosilyl) -2-methylbutane, 1,4-di (dibutylfluorosilyl) -2-methylbutane, 1,2-di (dimethylfluorosilyl) acetylene, 1,2-di (diethylfluoro) Silyl) acetylene, 1,2-di (dipropylfluorosilyl) acetylene, 1,2-di (dibutylfluorosilyl) acetylene, 1,4-di (dimethylfluorosilyl) benzene, 1,3-di (dimethylfluorosilyl) ) Benzene, 1,2-di (dimethylfluorosilyl) benzene and the like.

  Of the compounds represented by the general formula (6), X is a group represented by the general formula (8), and Y in the general formula (8) is an oxygen atom. Specific examples include 3-methoxypropyldimethylfluorosilane, 3-ethoxypropyldimethylfluorosilane, 3-propoxypropyldimethylfluorosilane, 3-butoxypropyldimethylfluorosilane, 3-pentoxypropyldimethylfluorosilane, 3- Hexoxypropyldimethylfluorosilane, 4-methoxybutyldimethylfluorosilane, 4-ethoxybutyldimethylfluorosilane, 4-propoxybutyldimethylfluorosilane, 4-butoxybutyldimethylfluorosilane, 4-pentoxybutyldimethylfluorosilane, 4- Hexoxybuty Dimethyl fluorosilane, and the like.

  Of the compounds represented by the general formula (6), X is a group represented by the general formula (8), and Y in the general formula (8) is an oxygen atom. Specific examples include 3-methoxypropyldimethylfluorosilane, 3-ethoxypropyldimethylfluorosilane, 3-propoxypropyldimethylfluorosilane, 3-butoxypropyldimethylfluorosilane, 3-pentoxypropyldimethylfluorosilane, 3- Hexoxypropyldimethylfluorosilane, 4-methoxybutyldimethylfluorosilane, 4-ethoxybutyldimethylfluorosilane, 4-propoxybutyldimethylfluorosilane, 4-butoxybutyldimethylfluorosilane, 4-pentoxybutyldimethylfluorosilane, 4- Hexoxybuty Dimethyl fluorosilane, and the like.

  Moreover, as a specific example of a preferable compound among the compounds in which X is a group represented by the general formula (8) and Y in the general formula (8) is a —C (═O) —O— group. For example, 2- (dimethylfluorosilyl) ethyl acetate, 3- (dimethylfluorosilyl) propyl acetate, 3- (dimethylfluorosilyl) butyl acetate, 3- (dimethylfluorosilyl) pentyl acetate, acetic acid- 3- (dimethylfluorosilyl) hexyl, propionate-2- (dimethylfluorosilyl) ethyl, propionate-3- (dimethylfluorosilyl) propyl, propionate-3- (dimethylfluorosilyl) butyl, propionate-3- (Dimethylfluorosilyl) pentyl, propionic acid-3- (dimethylfluorosilyl) hexyl, butanoic acid-2- (dimethylphenol) Orosilyl) ethyl, butanoic acid-3- (dimethylfluorosilyl) propyl, butanoic acid-4- (dimethylfluorosilyl) butyl, butanoic acid-5- (dimethylfluorosilyl) pentyl, butanoic acid-6- (dimethylfluorosilyl) And hexyl.

  Further, X is a group represented by the general formula (8), and Y in the general formula (8) is represented by the general formula (6), which is an —O—C (═O) — group. Specific examples of preferable compounds among the compounds include, for example, methyl dimethylfluorosilyl acetate, ethyl dimethylfluorosilyl acetate, butyl dimethylfluorosilyl acetate, pentyl dimethylfluorosilyl acetate, hexyl dimethylfluorosilyl acetate, 3- (dimethylfluorosilyl ) Methyl propionate, ethyl 3- (dimethylfluorosilyl) propionate, propyl 3- (dimethylfluorosilyl) propionate, butyl 3- (dimethylfluorosilyl) propionate, pentyl 3- (dimethylfluorosilyl) propionate, 3 -(Dimethylfluorosilyl) hexyl propionate, 4- (dimethyl Fluorosilyl) methyl butanoate, ethyl 4- (dimethylfluorosilyl) butanoate, propyl 4- (dimethylfluorosilyl) butanoate, butyl 4- (dimethylfluorosilyl) butanoate, pentyl 4- (dimethylfluorosilyl) butanoate, 4- (dimethylfluorosilyl) butanoic acid hexyl and the like.

  The other fluorosilane compounds may be used alone or in combination of two or more.

  The organic disilane compound is a compound having one Si-Si bond in the molecule, and the organic disiloxane compound is a compound having one Si-O-Si bond in the molecule. (E) As a preferable organic disilane or organic disiloxane compound as a component, the compound represented by following General formula (9) is mentioned.

（式中、Ｒ¹⁴及びＲ¹⁵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、炭素数２〜８のアルキニル基、炭素数１〜８のハロゲン化アルキル基、炭素数２〜８のアルコキシアルキル基、ハロゲン原子を有してもよい炭素数６〜１８のアリール基又は炭素数７〜１８のアラルキル基を表わし、Ｒ¹⁶は炭素数２〜８のアルケニル基、炭素数２〜８のアルキニル基、ハロゲン原子を有してもよい炭素数６〜１８のアリール基又は炭素数７〜１８のアラルキル基を表わし、ａは０又は１の数を表わす。）

Wherein R ¹⁴ and R ¹⁵ are each independently 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 an alkyl halide having 1 to 8 carbon atoms. Group, an alkoxyalkyl group having 2 to 8 carbon atoms, an aryl group having 6 to 18 carbon atoms which may have a halogen atom, or an aralkyl group having 7 to 18 carbon atoms, R ¹⁶ is an alkenyl having 2 to 8 carbon atoms A group, an alkynyl group having 2 to 8 carbon atoms, an aryl group having 6 to 18 carbon atoms which may have a halogen atom, or an aralkyl group having 7 to 18 carbon atoms, and a represents a number of 0 or 1.)

In the general formula (9), R ¹⁴ and R ¹⁵ are each independently 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 1 to 8 carbon atoms. A halogenated alkyl group, an alkoxyalkyl group having 2 to 8 carbon atoms, an aryl group having 6 to 18 carbon atoms which may have a halogen atom, or an aralkyl group having 7 to 18 carbon atoms, and R ¹⁶ represents a carbon number of 2 Represents an alkenyl group having 8 to 8 carbon atoms, an alkynyl group having 2 to 8 carbon atoms, an aryl group having 6 to 18 carbon atoms which may have a halogen atom, or an aralkyl group having 7 to 18 carbon atoms. 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, a halogenated alkyl group having 1 to 8 carbon atoms, and 6 to 6 carbon atoms which may have a halogen atom Examples of the 18 aryl group and the aralkyl group having 7 to 18 carbon atoms include alkyl groups, alkenyl groups, alkynyl groups, halogenated alkyl groups, and halogen atoms exemplified in the description of R ⁹ and R ^{10 in} the general formula (6). An aryl group or an aralkyl group which may be included is exemplified.

  Examples of the alkoxyalkyl group having 2 to 8 carbon atoms include methoxymethyl, methoxyethyl, methoxypropyl, ethoxyethyl, methoxybutyl, ethoxypropyl, propoxyethyl, methoxypentyl, ethoxybutyl, propoxypropyl, butoxyethyl, pentoxyethyl. , Butoxypropyl, hexoxyethyl, pentoxypropyl and the like.

R ¹⁴ and R ¹⁵ are preferably methyl, ethyl, propyl, isopropyl, butyl, pentyl, 3-chloropropyl, 3-chlorobutyl and 4-chlorobutyl because the internal resistance of the nonaqueous electrolyte secondary battery is reduced. Methyl, ethyl and propyl are more preferred, and methyl and ethyl are most preferred. For the same reason, R ¹⁶ is preferably vinyl or ethynyl, and more preferably vinyl.

  In the general formula (9), a represents a number of 0 or 1. When a is 0, the general formula (9) represents an organic disilane compound, and when a is 1, the general formula (9) represents an organic disiloxane compound.

  When a is 0, that is, preferable specific examples of the organic disilane compound include, for example, 1,2-divinyl-1,1,2,2-tetramethyldisilane, 1,2-divinyl-1,1,2, 2-tetraethyldisilane, 1,2-divinyl-1,1,2,2-tetrapropyldisilane, 1,2-divinyl-1,1,2,2-tetrabutyldisilane, 1,2-divinyl-1,1 , 2,2-tetrapentyldisilane, 1,2-divinyl-1,1,2,2-tetrahexyldisilane, 1,2-diethynyl-1,1,2,2-tetramethyldisilane, 1,2-diethynyl -1,1,2,2-tetraethyldisilane, 1,2-diethynyl-1,1,2,2-tetrapropyldisilane, 1,2-diethynyl-1,1,2,2-tetrabutyldisilane, 1, 2-diechi Le 1,1,2,2-pentyl disilane, 1,2-diethynyl-1,1,2,2-hexyl disilane and the like.

  When a is 1, that is, preferable specific examples of the organic disiloxane compound include, for example, 1,3-divinyl-1,1,3,3-tetraethyldisiloxane, 1,3-divinyl-1,1,3. , 3-tetrapropyldisiloxane, 1,3-divinyl-1,1,3,3-tetrabutyldisiloxane, 1,3-divinyl-1,1,3,3-tetrapentyldisiloxane, 1,3- Divinyl-1,1,3,3-tetrahexyldisiloxane, 1,3-diethynyl-1,1,3,3-tetramethyldisiloxane, 1,3-diethynyl-1,1,3,3-tetraethyldi Siloxane, 1,3-diethynyl-1,1,3,3-tetrapropyldisiloxane, 1,3-diethynyl-1,1,3,3-tetrapentyldisiloxane, 1,3-diethynyl-1,1, , 3-tetra-hexyl disiloxane and the like.

  Examples of the organic disilane or the organic disiloxane compound include 1,2-divinyl-1,1,2,2-tetramethyldisilane, 1,2-divinyl-1,1,2,2-tetraethyldisilane, 1,3-divinyl, Divinyl-1,1,3,3-tetraethyldisiloxane and 1,3-divinyl-1,1,3,3-tetrapropyldisiloxane are preferred, and 1,2-divinyl-1,1,2,2-tetra More preferred are methyldisilane and 1,3-divinyl-1,1,3,3-tetraethyldisiloxane. The organic disilane or the organic disiloxane compound may be used alone or in combination of two or more.

  As the component (E), the sulfite compound, sulfonate compound, alkali metal imide salt, other fluorosilane compound, and organic disilane or organic disiloxane compound may be used alone or in combination. May be used. When used alone, a sulfite ester compound or a sulfonic acid ester compound is preferable. When used in combination, it is preferable to combine a sulfite ester compound or a sulfonic acid ester compound with another component (E).

  In the non-aqueous electrolyte for a secondary battery of the present invention, when the content of the component (E) is too small, a sufficient effect cannot be exhibited, and when it is too large, an increase effect corresponding to the content is obtained. In addition, since the properties of the non-aqueous electrolyte for secondary batteries may be adversely affected, the content of the component (E) is 0. 0% in the non-aqueous electrolyte for secondary batteries of the present invention. 01-5 mass% is preferable, 0.03-4 mass% is still more preferable, 0.05-3 mass% is the most preferable.

  The non-aqueous electrolyte for a secondary battery of the present invention is formed from an unsaturated cyclic carbonate compound, an unsaturated chain, 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 from the viewpoint of stability. It is preferable to contain one or more compounds selected from the group consisting of a carbonate compound, an unsaturated diester compound, and a halogen-containing cyclic carbonate compound (hereinafter sometimes referred to as component (F)). In the present invention, the unsaturated cyclic carbonate compound refers to a carbonate compound having a carbon-carbon unsaturated bond inside or outside the ring having a carbonate group.

  Examples of the unsaturated cyclic carbonate compound include vinylene carbonate, 1-methyl vinylene carbonate, 1,2-dimethyl vinylene carbonate, 1-phenyl vinylene carbonate, 1,2-diphenyl vinylene carbonate, ethylidene ethyl carbonate, vinyl ethylene carbonate, Examples include 1,2-divinylethylene carbonate, styrene carbonate, 1,2-diphenylethylene carbonate, catechol carbonate, and the like.

  Examples of the unsaturated chain carbonate compound include allyl methyl carbonate, allyl ethyl carbonate, diallyl carbonate, methyl vinyl carbonate, divinyl carbonate, methyl phenyl carbonate, t-butyl phenyl carbonate, diphenyl carbonate, dibenzyl carbonate, dipropargyl carbonate. , Propargyl methyl carbonate, ethyl propargyl carbonate, bis (1-methylpropargyl) carbonate, bis (1,1-dimethylpropargyl) carbonate, 2-butyne-1,4-diol dimethyldicarbonate, 2-butyne-1,4- Diol diisopropyl dicarbonate, 2-butyne-1,4-diol bis (3-chloropropyl) dicarbonate, 2,4-hexadiyne 1,6-diol dimethyl dicarbonate, 2,4-hexadiyn-1,6-diol diisopropyl dicarbonate, 2,4-hexadiyn-1,6 Jiorubisu (3-chloropropyl) dicarbonate and the like.

  Examples of the unsaturated diester compound include dimethyl maleate, diethyl maleate, dipropyl maleate, dibutyl maleate, dipentyl maleate, dihexyl maleate, diheptyl maleate, dioctyl maleate, dimethyl fumarate, diethyl fumarate, Dipropyl fumarate, dibutyl fumarate, dipentyl fumarate, dihexyl fumarate, diheptyl fumarate, dioctyl fumarate, dimethyl acetylenedicarboxylate, diethyl acetylenedicarboxylate, dipropyl acetylenedicarboxylate, dibutyl acetylenedicarboxylate, dipentyl acetylenedicarboxylate, acetylene Examples include dihexyl dicarboxylate, diheptyl acetylenedicarboxylate, dioctyl acetylenedicarboxylate, and the like.

  Examples of the halogen-containing cyclic carbonate compound include chloroethylene carbonate, 1,2-dichloroethylene carbonate, fluoroethylene carbonate, 1,2-difluoroethylene carbonate, trifluoromethylethylene carbonate, and the like.

  As the component (F), vinylene carbonate, vinyl ethylene carbonate, dipropargyl carbonate, dimethyl acetylenedicarboxylate, diethyl acetylenedicarboxylate, chloroethylene carbonate and dichloroethylene carbonate are preferable, vinylene carbonate, dipropargyl carbonate, dimethyl acetylenedicarboxylate and Chloroethylene carbonate is more preferred, with vinylene carbonate, dipropargyl carbonate and chloroethylene carbonate being most preferred.

  As the component (F), only one type may be used, or two or more types may be used in combination. In the non-aqueous electrolyte for a secondary battery of the present invention, when the content of the component (F) is too small, a sufficient effect cannot be exhibited, and when it is too large, an increase effect corresponding to the content cannot be obtained. In addition, since the properties of the non-aqueous electrolyte for secondary batteries may be adversely affected, the content of the component (F) is 0.005 in the non-aqueous electrolyte for secondary batteries of the present invention. Is preferably 10 to 10% by mass, more preferably 0.02 to 5% by mass, and most preferably 0.05 to 3% by mass.

  In addition, in order to impart flame retardancy, halogen-based, phosphorus-based, and other flame retardants can be appropriately added to the non-aqueous electrolyte for secondary batteries of the present invention. If the amount of flame retardant added is too small, it will not be able to exert a sufficient flame retardant effect, and if it is too large, it will not be possible to obtain an increase effect commensurate with the content, but on the contrary, non-aqueous electrolysis for secondary batteries Since it may adversely affect the properties of the liquid, it is preferably 5 to 100% by mass and preferably 10 to 50% by mass in the organic solvent constituting the non-aqueous electrolyte for secondary battery of the present invention. Is more preferable.

Next, the nonaqueous electrolyte secondary battery of the present invention will be described.
The electrode material constituting the non-aqueous electrolyte secondary battery of the present invention includes a positive electrode and a negative electrode. As the positive electrode of the secondary battery, a positive electrode active material, a binder (binder), and a conductive material are combined with an organic solvent or A slurry formed with water is applied to a current collector, dried, and rolled as necessary to form a sheet.

The positive electrode active material is not particularly limited as long as it can electrochemically occlude and release lithium ions, but is preferably a material 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. The transition metal of the lithium-containing transition metal phosphate compound is preferably vanadium, titanium, manganese, iron, cobalt, nickel or the like. Specific examples thereof include iron phosphates such as LiFePO ₄ and phosphoric acid such as LiCoPO _4. Cobalt, some of the transition metal atoms that are the main components of these lithium transition metal phosphate compounds are aluminum, titanium, vanadium, chromium, manganese, iron, cobalt, lithium, nickel, copper, zinc, magnesium, gallium, zirconium, Examples include those substituted with other metals such as niobium.

  As the positive electrode active material used for the positive electrode of the non-aqueous electrolyte secondary battery of the present invention, a lithium cobalt composite oxide is preferable because a high voltage can be stably obtained. However, a high voltage is obtained and the raw material is also inexpensive. Therefore, a positive electrode active material containing manganese, nickel, or iron is preferable. Particularly, the active material is a lithium-nickel-containing composite oxide or a material in which a part of the nickel atom is substituted with another metal, a lithium iron phosphate compound Or it is more preferable that a part of the 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 electrolytic solution is likely to occur, but the non-aqueous electrolyte secondary battery of the present invention has the above general formula in the non-aqueous electrolytic solution. By containing the difluorosilane compound represented by (1), the electrolytic solution is less decomposed, and it is possible to maintain a small internal resistance and a high electric capacity even after high-temperature storage.

  Examples of the binder for the positive electrode active material 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 carbon nanofibers, 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 or water that dissolves the binder 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, 30-300 mass parts is preferable with respect to 100 mass parts of positive electrode active materials, and, as for the usage-amount of the said solvent, 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.

  As the negative electrode, a negative electrode active material and a binder (binder) that are slurried with an organic solvent or water are applied to a current collector and dried to form a sheet.

  Examples of the negative electrode active material include inorganic compounds such as lithium, lithium alloys, and tin / silicon compounds, titanium oxides, carbonaceous materials, and conductive polymers. In particular, a carbonaceous material that can occlude and release highly safe lithium ions is preferable. This carbonaceous material is roughly classified into graphite and amorphous carbon. Amorphous carbon is soft carbon (easily graphitized) that undergoes graphitization by heat treatment at about 2000 ° C. due to the ease of crystallization (graphitization) due to heat. And hard carbon (also referred to as non-graphitizable carbon) that hardly undergoes graphitization even by heat treatment at 2800 ° C. or higher. Examples of graphite include artificial graphite such as mesophase carbon microbeads (MCMB) and graphitized mesophase pitch-based carbon fibers (MCF), natural graphite, and the like. Examples of the soft carbon include coke, mesophase pitch carbon fiber, and pyrolytic vapor grown carbon fiber. Examples of hard carbon include phenol resin fired products, furan resin fired products, oxidized petroleum pitch fired products, polyacrylonitrile-based carbon fibers (PAN-based carbon fibers), glassy carbon (glassy carbon), and the like.

  Examples of the binder for the negative electrode active material and the solvent for forming the slurry include those similar to the binder and the solvent for the positive electrode active material. Moreover, copper, nickel, stainless steel, nickel-plated steel, etc. are normally used for the negative electrode current collector. The amount of the binder used is preferably 0.001 to 5 parts by mass, more preferably 0.05 to 3 parts by mass, and 0.01 to 2 parts by mass with respect to 100 parts by mass of the negative electrode active material. Most preferred. The amount of the solvent used is preferably 30 to 300 parts by mass, and more preferably 50 to 200 parts by mass with respect to 100 parts by mass of the negative electrode active material.

  In the non-aqueous electrolyte secondary battery of the present invention, it is preferable to use a separator 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.

The shape of the nonaqueous electrolyte secondary battery of the present invention having the above-described 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 for a battery 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 polyethylene. Separator.

  Further, in the cylindrical nonaqueous electrolyte secondary battery 10 ′ shown in FIGS. 2 and 3, 11 is a negative electrode, 12 is a negative electrode current collector, 13 is a positive electrode, 14 is a positive electrode current collector, and 15 is the present invention. Nonaqueous electrolyte for batteries, 16 is a separator, 17 is a positive terminal, 18 is a negative terminal, 19 is a negative plate, 20 is a negative lead, 21 is a positive plate, 22 is a positive lead, 23 is a case, 24 is an insulating plate, 25 is a gasket, 26 is a safety valve, and 27 is a PTC element.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to the following examples. In the examples, “parts” and “%” are based on mass unless otherwise specified.

[Synthesis Example 1] Synthesis of Compound A1 188 g of cyclohexyldimethoxymethylsilane was charged into a 500 ml three-necked flask equipped with a refluxer, and 94.6 g of trifluoroborane diethyl etherate was added dropwise from a dropping funnel while cooling with water. After the dropwise addition, the reaction was further completed at room temperature for 6 hours, and then the reaction was completed. After the reaction, purification by vacuum distillation yielded 131 g (yield 80%) of the target compound A1 [cyclohexyldifluoromethylsilane].

Synthesis Example 2 Synthesis of Compound A2 174 g of cyclopentyldimethoxymethylsilane was charged into a 500 ml three-necked flask equipped with a refluxer, and 94.6 g of trifluoroborane diethyl etherate was added dropwise from a dropping funnel while cooling with water. After the dropwise addition, the reaction was further completed at room temperature for 6 hours, and then the reaction was completed. After the reaction, purification by vacuum distillation yielded 119 g (yield 79%) of the target compound A2 [cyclopentyldifluoromethylsilane].

[Synthesis Example 3] Synthesis of Compound A3 216 g of cyclooctyldimethoxymethylsilane was charged into a 500 ml three-necked flask equipped with a refluxer, and 94.6 g of trifluoroborane diethyl etherate was added dropwise from a dropping funnel while cooling with water. . After the dropwise addition, the reaction was further completed at room temperature for 6 hours, and then the reaction was completed. After the reaction, purification by vacuum distillation yielded 156 g (yield 81%) of the target compound A3 [cyclooctyldifluoromethylsilane].

[Examples 1 to 24 and Comparative Examples 1 to 26]
In the following examples and comparative examples, non-aqueous 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]
90 parts by mass of LiNi _1/3 Co _1/3 Mn _1/3 O ₂ (Nippon Chemical Industry Co., Ltd. CELLSEED NMC) as a positive electrode active material, 5 parts by mass of acetylene black as a conductive material, and polyvinylidene fluoride (PVDF) as a binder 5 parts by mass was mixed to obtain a positive electrode material. 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 a positive electrode current collector made of aluminum, 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]
As a positive electrode active material, 78 parts by mass of LiFePO ₄ , 18 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. 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 a positive electrode current collector made of aluminum, 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.

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. This negative electrode material was dispersed in 120 parts by mass of water to form a slurry. This slurry was applied to 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 hard carbon 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. This negative electrode material was dispersed in 120 parts by mass of water to form a slurry. This slurry was applied to 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 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.

c. Preparation of non-aqueous electrolyte [Preparation of electrolyte solution A]
LiPF ₆ was dissolved at a concentration of 1 mol / L in a mixed solvent composed 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 to prepare an electrolyte solution A.

[Preparation of electrolyte solution B]
LiPF ₆ was dissolved at a concentration of 1 mol / L in a mixed solvent composed of 30% by volume of ethylene carbonate, 40% by volume of ethyl methyl carbonate and 30% by volume of dimethyl carbonate to prepare an electrolyte solution B.

[Preparation of electrolyte solution C]
LiPF ₆ was dissolved at a concentration of 1 mol / L in a mixed solvent composed of 30% by volume of fluoroethylene carbonate, 40% by volume of ethyl methyl carbonate and 30% by volume of dimethyl carbonate to prepare an electrolyte solution C.

[Preparation of electrolyte solution D]
LiPF ₆ was dissolved at a concentration of 1 mol / L in a mixed solvent composed of 30% by volume of ethylene carbonate and 70% by volume of diethyl carbonate to prepare an electrolyte solution D.

(Preparation of non-aqueous electrolyte)
As an electrode additive, the compounds A1 to A3 obtained in Synthesis Examples 1 to 3, the following comparative compounds B1 to B3, the compounds C1 to C2, and the compounds D1 to D2 were mixed in the ratios shown in Table 1 or Table 2 to the electrolyte solutions A to A. Dissolved in D, the nonaqueous electrolytic solution of the present invention and the comparative nonaqueous electrolytic solution were prepared. The numbers in parentheses in Tables 1 and 2 represent the concentration (% by mass) in the non-aqueous electrolyte.

[Comparative Compound B1]
Cyclohexylfluorodimethylsilane [Comparative Compound B2]
Hexyldifluoromethylsilane [Comparative Compound B3]
Difluorophenylmethylsilane [Compound C1]
Ethyl bis (2-propynyl) phosphate [Compound C2]
Tris (2-propynyl) phosphate [Compound C3]
2,4-hexadiyne-1,6-diol tetraethyldiphosphate [Compound D1]
Vinylene carbonate [Compound D2]
Propane sultone

d. Assembling the Battery The obtained disk-shaped positive electrode A or positive electrode B and disk-shaped negative electrode A or B were held in a case with a polyethylene microporous film having a thickness of 25 μm interposed therebetween. Thereafter, each non-aqueous electrolyte solution is injected into the case so that the combination of the non-aqueous electrolyte solution of the present invention or the comparative non-aqueous electrolyte solution with the positive electrode and the negative electrode is as shown in Table 1 or Table 2, and the case is sealed. Then, a coin-type lithium secondary battery having a diameter of 20 mm and a thickness of 3.2 mm was manufactured, and the lithium secondary batteries of Examples 1 to 24 and Comparative Examples 1 to 26 were obtained.

  Using the lithium secondary batteries of Examples 1 to 24 and Comparative Examples 1 to 26, an initial characteristic test and a cycle characteristic test were performed by the following test methods. In the initial characteristic test, the discharge capacity ratio and the internal resistance ratio were obtained, and in the cycle characteristic test, the discharge capacity maintenance ratio and the internal resistance increase ratio were obtained.

<Initial characteristic test method for positive electrode A>
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 4.3 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, 4.3 V until a constant current and constant voltage charging at a charging current 0.3 mA / cm ^2, and a constant current discharge to 3.0V at a discharge current 0.3 mA / cm ^2. The discharge capacity measured at the sixth time is the initial discharge of the battery, and the discharge capacity ratio (%) is the ratio of the initial discharge capacity when the initial discharge capacity of Example 1 is 100 as shown in the following formula. Asked.
Discharge capacity ratio (%) = [(initial discharge capacity) / (initial discharge capacity in Example 1)] × 100

b. Measuring method of internal resistance ratio About the lithium secondary battery after measuring the discharge capacity at the sixth time, first, constant current charging was performed so that the SOC was 60% at a charging current of 1.5 mA / cm ² (current value equivalent to 1 C). Using an AC impedance measuring device (product name: mobile potentiostat CompactStat, manufactured by IVIUM TECHNOLOGIES), scanning is performed from a frequency of 100 kHz to 0.02 Hz, and the ordinate indicates the imaginary part and the abscissa indicates the real part. It 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

<Initial characteristic test method for positive electrode B>
The lithium secondary battery is placed in a constant temperature bath at 20 ° C., charged at a constant current and a constant voltage up to 4.0 V with a charging current of 0.3 mA / cm ² (current value corresponding to 0.2 C), and a discharge current of 0.3 mA / The operation of discharging a constant current to 2.0 V at 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 to 4.0 V at a charging current of 0.3 mA / cm ² and discharged at a constant current to 2.0 V 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 discharge capacity ratio (%) was determined in the same manner as the initial characteristic test method in the case of the positive electrode A. For the lithium secondary battery after measuring the discharge capacity at the sixth time, the internal resistance ratio (%) was determined in the same manner as the initial characteristic test method in the case of the positive electrode A.

<Cycle characteristic test method for positive electrode A>
a. Method for measuring discharge capacity retention rate The lithium secondary battery after the initial characteristic test was placed in a constant temperature bath at 60 ° C., and a charging current of 1.5 mA / cm ² (current value equivalent to 1 C, 1 C represents the battery capacity in 1 hour. The cycle of charging at a constant current up to 4.3 V at a discharge current value) and discharging at a constant current of up to 3.0 V at a discharge current of 1.5 mA / cm ² was repeated 300 times. The discharge capacity at the 300th time is defined as the discharge capacity after the cycle test. 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

<Cycle characteristic test method for positive electrode B>
The lithium secondary battery after the initial characteristic test is placed in a constant temperature bath at 60 ° C., and the charging current is 1.5 mA / cm ² (current value equivalent to 1C, 1C is the current value at which the battery capacity is discharged in 1 hour). A cycle in which constant current charging to 0.0 V and constant current discharging to 2.0 V at a discharge current of 1.5 mA / cm ² was repeated 300 times. The discharge capacity at the 300th time was defined as the discharge capacity after the cycle test, and the discharge capacity retention rate (%) was determined in the same manner as the cycle characteristic test method in the case of the positive electrode A. For the lithium secondary battery after the cycle test, the rate of increase in internal resistance (%) was determined in the same manner as the cycle characteristic test method for positive electrode A.

  As is clear from the results of Tables 3 and 4, the non-aqueous electrolyte secondary battery having the non-aqueous electrolyte containing the difluorosilane compound represented by the general formula (1) is a cycle test at 60 ° C. Later, it was confirmed that it was excellent in terms of internal resistance and discharge capacity and could maintain excellent battery characteristics.

Industrial applicability

  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 Nonaqueous electrolyte 4 for secondary batteries of this invention Positive electrode case 5 Negative electrode case 6 Gasket 7 Separator 10 Coin type nonaqueous electrolyte secondary battery 10 'Cylinder Type non-aqueous electrolyte secondary battery 11 negative electrode 12 negative electrode current collector 13 positive electrode 14 positive electrode current collector 15 non-aqueous electrolyte 16 for secondary battery of the present invention 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)

In the non-aqueous electrolyte for a secondary battery containing an organic solvent and an electrolyte salt, the organic solvent is one or more selected from the group consisting of a saturated cyclic carbonate compound, a saturated cyclic ester compound, a sulfoxide compound, a sulfone compound, and an amide compound. A non-aqueous electrolyte for a secondary battery comprising 0.01 to 5% by mass of a difluorosilane compound represented by the following general formula (1).

(In the formula, R ¹ represents a cycloalkyl group having 5 to 8 carbon atoms, and R ² represents an alkyl group having 1 to 8 carbon atoms.)   The organic solvent is one or more solvents selected from the group consisting of saturated cyclic carbonate compounds, saturated cyclic ester compounds, sulfoxide compounds, sulfone compounds and amide compounds, saturated chain carbonate compounds, chain ether compounds, and cyclic ether compounds. And a non-aqueous electrolyte for a secondary battery according to claim 1, which is a mixed solvent with at least one solvent selected from the group consisting of a saturated chain ester compound.   The nonaqueous electrolytic solution for a secondary battery according to claim 2, wherein the organic solvent is a mixed solvent containing 0.5 to 30% by mass of the saturated chain ester compound. Furthermore, 0.01-5 mass% of unsaturated phosphate ester compounds represented by the following general formula (2) or unsaturated phosphate ester compounds represented by the following general formula (3) are contained. The non-aqueous electrolyte for secondary batteries of any one of these.

(Wherein R ³ and R ⁴ each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R ⁵ 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.)

(Wherein R ⁶ and R ⁷ each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R ⁸ represents an alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, carbon A alkynyl group having 2 to 8 carbon atoms or a halogenated alkyl group having 1 to 8 carbon atoms, and m represents a number of 1 or 2. Furthermore, 0.01-5 mass% of 1 or more types of compounds chosen from the group which consists of a sulfite ester compound, a sulfonate ester compound, an imide salt of an alkali metal, another fluorosilane compound, and an organic disilane or an organic disiloxane compound. The non-aqueous electrolyte for secondary batteries of any one of Claims 1-4 contained. Furthermore, 0.005-10 mass% of 1 or more types of compounds chosen from the group which consists of an unsaturated cyclic carbonate compound, an unsaturated chain carbonate compound, an unsaturated diester compound, and a halogen-containing cyclic carbonate compound are contained. The nonaqueous electrolytic solution for a secondary battery according to any one of 5.   A nonaqueous electrolyte secondary battery comprising the negative electrode, the positive electrode, and the nonaqueous electrolyte solution for a secondary battery according to any one of claims 1 to 6.   The nonaqueous electrolyte secondary battery according to claim 7, wherein the positive electrode active material of the positive electrode is a positive electrode active material containing nickel or iron.

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