JP2017045503A - Additive for nonaqueous electrolyte secondary battery, electrode for nonaqueous electrolyte secondary battery, electrolyte for nonaqueous electrolyte secondary battery, and nonaqueous electrolyte secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an additive for a nonaqueous electrolyte secondary battery capable of improving both of cycle characteristics and output characteristics of the nonaqueous electrolyte secondary battery.SOLUTION: An additive for a nonaqueous electrolyte secondary battery is used which is composed of a non-addition-polymerizable compound (A) which includes: at least one kind of group (a) selected from the group consisting of an urethane group, an urea group, an allophanate group, a biuret group and an isocyanate group; and a fluorinated alkyl group (b1) obtained by substituting at least one of hydrogen atoms included in an alkyl group of 2 to 20 carbon atoms with a fluorine atom, and/or a fluorinated alkylene group (b2) obtained by substituting at least one of hydrogen atoms included in an alkylene group of 2 to 20 carbon atoms with a fluorine atom.SELECTED DRAWING: None

Description

  The present invention relates to an additive for non-aqueous electrolyte secondary batteries.

  Non-aqueous electrolyte secondary batteries such as lithium-ion batteries are characterized by high voltage and high energy density, so they are widely used in the field of portable information devices and are used for mobile terminals such as mobile phones and notebook computers. The position as a standard battery has been established. While its uses are expanding, application to hybrid vehicles and electric vehicles in addition to conventional uses is also being studied, and some have already been put into practical use. In order to further spread these, there is a demand for higher performance and higher capacity of secondary batteries, and various techniques have been applied.

As a technique for further increasing the capacity of the non-aqueous electrolyte secondary battery, a technique for increasing the charging voltage and increasing the utilization depth of the positive electrode active material has attracted attention. For example, in a cobalt composite oxide (LiCoO ₂ ) that is an active material of a non-aqueous electrolyte secondary battery having an operating voltage of 4.2 V class, a charge capacity of about 155 mAh / g when charged to 4.3 V based on the current Li standard. On the other hand, when the battery is charged to 4.5 V, the charge capacity becomes about 190 mAh / g or more.

  However, as the charging voltage of the battery increases, there are problems such as deterioration of charge / discharge cycle characteristics and swelling due to gas generation during high-temperature storage. In order to solve these problems, vinylene A technique of adding carbonate or fluoroethylene carbonate to an electrolytic solution (see Patent Documents 1 and 2) and a technique of adding a compound having a urethane bond and a hydrocarbon group substituted with a fluorine atom to an electrode or an electrolytic solution (see Patent Document 3) )It has been known.

  However, the methods described in Patent Documents 1 and 2 are not sufficient in improving the cycle characteristics, and the method described in Patent Document 3 improves the characteristics such as the cycle characteristics but has a problem that the output characteristics deteriorate. there were.

JP 2012-169249 A JP 2008-077950 A Japanese Patent Application Laid-Open No. 2014-137843

  An object of this invention is to provide the additive for nonaqueous electrolyte secondary batteries which can improve both the cycling characteristics and output characteristics of a nonaqueous electrolyte secondary battery.

  As a result of intensive studies to achieve the above object, the present inventors have reached the present invention. That is, the present invention includes at least one group (a) selected from the group consisting of a urethane group, a urea group, an allophanate group, a biuret group, and an isocyanate group, and at least a hydrogen atom of an alkyl group having 2 to 20 carbon atoms. Fluorinated alkylene in which at least one hydrogen atom is substituted with a fluorine atom among the fluorinated alkyl group (b1) in which one hydrogen atom is substituted with a fluorine atom and / or the hydrogen atom of an alkylene group having 2 to 20 carbon atoms An additive for a non-aqueous electrolyte secondary battery comprising a non-addition polymerizable compound (A) having a group (b2); a non-aqueous electrolyte secondary battery containing the additive for a non-aqueous electrolyte secondary battery .

  The non-aqueous electrolyte secondary battery containing the additive for non-aqueous electrolyte secondary batteries of the present invention is excellent in cycle characteristics and output characteristics.

  The additive for a non-aqueous electrolyte secondary battery of the present invention has at least one group (a) selected from the group consisting of a urethane group, a urea group, an allophanate group, a biuret group, and an isocyanate group, and has 2 to 20 carbon atoms. At least one hydrogen atom among the hydrogen atoms of the fluorinated alkyl group (b1) in which at least one hydrogen atom of the alkyl group has a fluorine atom and / or the alkylene group having 2 to 20 carbon atoms is substituted It is characterized by comprising an additive for a non-aqueous electrolyte secondary battery comprising a non-addition polymerizable compound (A) having a fluorinated alkylene group (b2) substituted with a fluorine atom.

The compound (A) contains at least one group (a) selected from the group consisting of a urethane group, a urea group, an allophanate group, a biuret group and an isocyanate group. Since these groups have high polarity and high affinity with the active material surface constituting the electrode, the concentration of the non-addition polymerizable compound (A) in the vicinity of the active material is increased, and the performance of the nonaqueous electrolyte secondary battery Contributes to improvement. Of the groups (a), a urethane group and a urea group are particularly preferable from the viewpoint of adsorptivity to the active material.
The non-addition polymerizable compound (A) may contain a plurality of groups (a) in the molecule, and the group possessed by the non-addition polymerizable compound (A) [hereinafter also referred to as compound (A)]. The number of (a) is preferably 1 to 20, more preferably 2 to 10. When the non-addition polymerizable compound (A) has a plurality of groups (a), the plurality of groups (a) may be the same or different.

  In the compound (A), a fluorinated alkyl group (b1) in which at least one hydrogen atom in a hydrogen atom of an alkyl group having 2 to 20 carbon atoms is substituted with a fluorine atom and / or an alkylene group having 2 to 20 carbon atoms. The fluorinated alkylene group (b2) in which at least one hydrogen atom among the hydrogen atoms is substituted with a fluorine atom is contained. The fluorinated alkyl group (b1) and the fluorinated alkylene group (b2) are considered to interact chemically or electrochemically with the electrode surface and contribute to the improvement of high potential cycle characteristics.

  Preferred examples of the fluorinated alkyl group (b1) include 2-fluoroethyl group, 2,2-difluoroethyl group, 2,2,2-trifluoroethyl group, 2,2,3,3-tetrafluoropropyl. Group, 2,2,3,3,4,4,5,5-octafluoropentyl group, 1H, 1H, 7H-dodecafluoroheptyl group, 1H, 1H, 2H, 2H-heptadecafluorodecyl and perfluorocyclohexyl Examples thereof include a methyl group. Of these, 2-fluoroethyl group, 2,2,2-trifluoroethyl group and 2,2,3,3,4,4,5,5-octafluoropentyl group are preferably used from the viewpoint of battery characteristics.

  Preferred as the fluorinated alkylene group (b2) are 2,2,3,3-tetrafluorobutylene group, 2,2,3,3,4,4,5,5-octafluorohexamethylene, 1H, Examples thereof include 1H, 10H, 10H-hexadecafluorodecamethylene group and perfluorodecamethylene group. Of these, 2,2,3,3-tetrafluorobutylene group and 2,2,3,3,4,4,5,5-octafluorohexamethylene are preferably used from the viewpoint of battery characteristics.

Compound (A) is non-addition polymerizable. Non-addition polymerizable means that no addition polymerization (radical polymerization or the like) occurs, and the compound (A) is a polymerizable unsaturated bond (polymerizable carbon-carbon double bond, polymerizable carbon-carbon triple bond and A polymerizable carbon-nitrogen triple bond or the like).
When it has a polymerizable unsaturated bond, a film called Solid Electrolyte Interface (hereinafter abbreviated as SEI) is easily formed on the electrode. SEI also has the effect of suppressing the decomposition of the electrolyte, but if SEI is easily formed, it has the problem that the film thickness of SEI increases and the electrode resistance increases, so it has a polymerizable unsaturated bond. Is not preferred.
In addition, since the carbon-carbon double bond which comprises an aromatic compound among carbon-carbon double bonds does not have addition polymerizability, it is not contained in the said polymerizable unsaturated bond.

The compound (A) contained in the additive for non-aqueous electrolyte secondary batteries of the present invention is preferably a compound represented by the following general formula (1).

In the general formula (1), R ¹ is a residue obtained by removing all isocyanate groups from an m-valent isocyanate compound which may have a fluorine atom, and m is an integer of 1 to 6.
When m is 1 or 2, at least one of X ¹ and R ¹ is a group having a fluorine atom, and when m is an integer of 3 to 6, X ¹ is a group having a fluorine atom, When X is an integer of 2 to 6, a plurality of X ¹ may be the same or different.

Examples of the m-valent isocyanate compound that may have a fluorine atom include 1 to 6-valent isocyanate compounds that may have a fluorine atom, and a monoisocyanate compound having 2 to 20 carbon atoms (ethyl isocyanate, Butyl isocyanate, octyl isocyanate, dodecyl isocyanate, phenyl isocyanate and the like) and polyisocyanates having 4 to 20 carbon atoms.
Examples of the polyisocyanate having 4 to 20 carbon atoms include aromatic poly (2 to 6 valent) isocyanates having 8 to 20 carbon atoms, aliphatic poly (2 to 6 valent) isocyanates having 4 to 20 carbon atoms, and 8 to 18 carbon atoms. Alicyclic poly (2-6 valent) isocyanates, C10-18 araliphatic poly (2-6 valent) isocyanates, and modified products of these polyisocyanates.

  As aromatic polyisocyanate having 8 to 20 carbon atoms, 1,3- or 1,4-phenylene diisocyanate, 2,4- or 2,6-tolylene diisocyanate (hereinafter, tolylene diisocyanate is abbreviated as TDI), crude TDI, 4,4′- or 2,4′-diphenylmethane diisocyanate (hereinafter, diphenylmethane diisocyanate is abbreviated as MDI), crude MDI, polyarylpolyisocyanate, 4,4′-diisocyanatobiphenyl, 3,3′-dimethyl -4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatodiphenylmethane, 1,5-naphthylene diisocyanate, 4,4 ', 4 "-triphenylmethane triisocyanate and m- or p-isocyanatophenylsulfonyl isocyanate, etc. And the like.

  Examples of aliphatic polyisocyanates having 4 to 20 carbon atoms include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (hereinafter abbreviated as HDI), 2,2,3,3,4,4,5,5-octafluorohexa Methylene diisocyanate, dodecane methylene diisocyanate, 1,6,11-undecane triisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2,6-diisocyanatomethyl caproate, bis (2-isocyanatoethyl) Examples thereof include fumarate, bis (2-isocyanatoethyl) carbonate and 2-isocyanatoethyl-2,6-diisocyanatohexanoate.

  Examples of the alicyclic polyisocyanate having 8 to 18 carbon atoms include isophorone diisocyanate (hereinafter abbreviated as IPDI), 4,4′-dicyclohexylmethane diisocyanate (hereinafter abbreviated as hydrogenated MDI), cyclohexylene diisocyanate, and methylcyclohexylene diisocyanate. Bis (2-isocyanatoethyl) -4-cyclohexene-1,2-dicarboxylate and 2,5- or 2,6-norbornane diisocyanate.

  Examples of the araliphatic polyisocyanate having 10 to 18 carbon atoms include m- or p-xylylene diisocyanate and α, α, α ′, α′-tetramethylxylylene diisocyanate.

  Examples of modified polyisocyanates include urethane group, carbodiimide group, allohanate group, urea group, biuret group, uretdione group, uretoimine group, isocyanurate group or oxazolidone group-containing modified product of polyisocyanate (content of free isocyanate group is Usually 8 to 33 wt%, preferably 10 to 30 wt%, especially 12 to 29 wt%), modified MDI (urethane modified MDI, carbodiimide modified MDI, trihydrocarbyl phosphate modified MDI, etc.), urethane modified TDI, biuret modified Examples thereof include modified polyisocyanates such as HDI, isocyanurate-modified HDI, and isocyanurate-modified IPDI.

In General Formula (1), X ¹ is a monovalent group or an isocyanate group represented by the following General Formula (2).

In general formula (2), R ² represents a fluorinated alkyl group in which at least one hydrogen atom is substituted with a fluorine atom among hydrogen atoms of an alkyl group having 2 to 20 carbon atoms or a fluorine atom having 1 to 20 carbon atoms. It is a monovalent organic group that does not have. Examples of the fluorinated alkyl group in which at least one hydrogen atom among the hydrogen atoms of the alkyl group having 2 to 20 carbon atoms is substituted with a fluorine atom include the same as the fluorinated alkyl group (b1), and are preferable. The same is true.

  Examples of the monovalent organic group having no fluorine atom having 1 to 20 carbon atoms include a monovalent hydrocarbon group having no fluorine atom having 1 to 20 carbon atoms. -20 saturated hydrocarbon groups (such as methyl, butyl, hexyl and decyl groups), alicyclic hydrocarbon groups having 6 to 20 carbon atoms (such as cyclohexyl and cyclopentyl groups) and fragrances having 6 to 20 carbon atoms Group hydrocarbon groups (phenyl group, biphenyl group, naphthyl group, etc.) and the like.

In the general formula (2), Z ¹ is an oxygen atom or an imino group, preferably an oxygen atom.
In general formula (2), * ¹ represents binding to R ¹ in general formula (1) by the bond to which it is attached.

In the general formula (1), m is 2, and R ¹ can be a divalent group represented by the following general formula (3).

In General Formula (3), R ³ , R ⁵ and R ⁷ are each a residue obtained by removing an isocyanate group from a C 4-20 diisocyanate compound which may have a fluorine atom.
As a C4-C20 diisocyanate compound which may have a fluorine atom, among C1-C6 valent isocyanate compounds which may have a fluorine atom, a C4-C20 divalent divalent compound. Preferred examples of the diisocyanate compound include hexamethylene diisocyanate, isophorone diisocyanate, trimethylhexamethylene diisocyanate, dicyclohexylmethane diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, tolylene diisocyanate, and 2,2,3,3,4,4. , 5,5-octafluorohexamethylene diisocyanate and the like.

In general formula (3), R ⁴ and R ⁶ are each independently a fluorinated alkylene group in which at least one hydrogen atom is substituted with a fluorine atom among the hydrogen atoms of the alkylene group having 2 to 20 carbon atoms, or 1 carbon atom. It is a bivalent organic group which does not have a fluorine atom of -20.

  Examples of the fluorinated alkylene group in which at least one hydrogen atom among the hydrogen atoms of the alkylene group having 2 to 20 carbon atoms is substituted with a fluorine atom include the same as the fluorinated alkylene group (b2), and are preferable. The same is true.

  Examples of the divalent organic group having no fluorine atom having 1 to 20 carbon atoms include a divalent hydrocarbon group having 1 to 20 carbon atoms, and preferred examples thereof include aliphatic carbonization having 1 to 20 carbon atoms. Hydrogen group (methylene group, ethylene group, propylene group, tetramethylene group, 2,2-dimethylpropylene group, hexamethylene group, etc.) and alicyclic hydrocarbon group having 1 to 20 carbon atoms (excluding hydroxyl group from cyclohexanedimethanol) And the like.

In General Formula (3), Z ^{2 to} Z ⁵ are each an oxygen atom or an imino group, preferably an oxygen atom.

In General Formula (3), at least one group among the groups represented by R ^{3 to} R ⁷ has a fluorine atom, and k is an integer of 1 to 10.
In general formula (3), * ² represents binding to X ¹ in general formula (1) by the bond to which it is attached.

In the general formula (1), at least ^one of X ¹ and R ¹ is a group having a fluorine atom, and X ¹ preferably has a fluorine atom.

  As a preferable compound (A), the compound which is the following combination in General formula (1) is mentioned.

In the general formula (1), X ¹ is an isocyanate group, m is 2, and R ¹ is two isocyanate groups from 2,2,3,3,4,4,5,5-octafluorohexamethylene diisocyanate. A compound that is a residue excluding.

In General Formula (1), X ¹ is a group represented by General Formula (2), and R ² in General Formula (2) is a 2,2,2-trifluoroethyl group, 2,2,3, 3-tetrafluoropropyl group or 1,1,1,3,3,3-hexafluoro-2-propyl group, Z ¹ is an oxygen atom or imino group, m is 1 and R ¹ is butyl A group, hexyl group, octyl group, cyclohexyl group or phenyl group, m is 2 and R ¹ is a residue obtained by removing two isocyanate groups from hexamethylene diisocyanate, a residue obtained by removing two isocyanate groups from isophorone diisocyanate, A residue obtained by removing two isocyanate groups from dicyclohexylmethane diisocyanate or a residue obtained by removing two isocyanate groups from tolylene diisocyanate, or m is 3. ¹ compound is a residue obtained by removing the isocyanurate trimer of three isocyanate groups of residues or hexamethylene diisocyanate except for three isocyanate groups from biuret modified product of hexamethylene diisocyanate.

In general formula (1), ^{X 1} is a group represented by the general formula (2), ^{R 2} in the general formula (2) is 6-20 saturated hydrocarbon group or a C 1 to 20 carbon atoms An alicyclic hydrocarbon group, Z ¹ is an oxygen atom or imino group, m is 2 and R ¹ is 2,2,3,3,4,4,5,5-octafluorohexamethylene diisocyanate The compound which is a residue remove | excluding two isocyanate groups from.

In general formula (1), ^{X 1} is a group represented by the general formula (2), ^{R 2} in the general formula (2) is 6-20 saturated hydrocarbon group or a C 1 to 20 carbon atoms An alicyclic hydrocarbon group, Z ¹ is an oxygen atom or imino group, R ¹ is a group represented by the formula (3), and R ² , R ⁴ and R ⁶ are each 2 from hexamethylene diisocyanate. A residue obtained by removing two isocyanate groups from isophorone diisocyanate, a residue obtained by removing two isocyanate groups from dicyclohexylmethane diisocyanate, or a residue obtained by removing two isocyanate groups from tolylene diisocyanate. Each of R ³ and R ⁵ is a 2,2,3,3-tetrafluorobutylene group or 2,2,3,3,4,4,5,5-octafluorohexamethyl. A compound which is a ren group and each of Z ^{1 to} Z ⁴ is an oxygen atom or an imino group.

In general formula (1), ^{X 1} is a group represented by the general formula (2), ^{R 2} in the general formula (2) is 6-20 saturated hydrocarbon group or a C 1 to 20 carbon atoms An alicyclic hydrocarbon group, Z ¹ is an oxygen atom or imino group, R ¹ is a group represented by the formula (3), and R ² , R ⁴ and R ⁶ are ² , ² , 3 respectively. , 3,4,4,5,5-octafluorohexamethylene diisocyanate from which two isocyanate groups are removed, R ³ and R ⁵ are a methylene group, an ethylene group, a propylene group, a tetramethylene group, 2 , 2-dimethylpropylene group or hexamethylene group, and Z ^{1 to} Z ⁴ are each an oxygen atom or an imino group.

In General Formula (1), X ¹ is an isocyanate group, R ¹ is a group represented by Formula (3), and R ² , R ^4, and R ⁶ are each obtained by removing two isocyanate groups from hexamethylene diisocyanate. A residue obtained by removing two isocyanate groups from isophorone diisocyanate, a residue obtained by removing two isocyanate groups from dicyclohexylmethane diisocyanate, or a residue obtained by removing two isocyanate groups from tolylene diisocyanate, and R ³ and R ⁵ is a 2,2,3,3-tetrafluorobutylene group or a 2,2,3,3,4,4,5,5-octafluorohexamethylene group, and Z ^{1 to} Z ⁴ are each an oxygen atom Or the compound which is an imino group.

In the general formula (1), X ¹ is an isocyanate group, R ¹ is a group represented by the formula (3), and R ² , R ^4, and R ⁶ are ² , ² , 3, 3, ⁴ , respectively. Residue obtained by removing two isocyanate groups from 4,5,5-octafluorohexamethylene diisocyanate, and R ³ and R ⁵ are a methylene group, an ethylene group, a propylene group, a tetramethylene group, and 2,2-dimethylpropylene, respectively. A compound which is a group or a hexamethylene group, and Z ^{1 to} Z ⁴ are each an oxygen atom or an imino group.

In General Formula (1), X ¹ is a group represented by General Formula (2), and R ² in General Formula (2) is a 2,2,2-trifluoroethyl group, 2,2,3, 3-tetrafluoropropyl group or 1,1,1,3,3,3-hexafluoro-2-propyl group, Z ¹ is an oxygen atom or imino group, and R ¹ is represented by formula (3). R ² , R ⁴ and R ⁶ are residues obtained by removing two isocyanate groups from hexamethylene diisocyanate, residues obtained by removing two isocyanate groups from isophorone diisocyanate, and two isocyanate groups from dicyclohexylmethane diisocyanate, respectively. Or a residue obtained by removing two isocyanate groups from tolylene diisocyanate, and R ³ and R ⁵ are a methylene group, an ethylene group, and propylene, respectively. Group, tetramethylene group, 2,2-dimethylpropylene group or hexamethylene group, and Z ^{1 to} Z ⁴ are each an oxygen atom or an imino group.

  Among these, as the compound (A), those represented by the following chemical formulas (4) to (15) are more preferable.

The compound (A) can be obtained by reacting a corresponding isocyanate compound with an alcohol compound or an amine compound. When an alcohol compound is used, a compound (A) having a urethane group is obtained, and when an amine compound is used, a compound having a urea group can be obtained.
The isocyanate compound, alcohol compound and amine compound used in the synthesis of the compound (A) do not have a polymerizable unsaturated bond, and at least one of them is a fluorinated hydrocarbon in which a hydrogen atom is substituted with a fluorine atom. Has a group.

  The content of the compound (A) contained in the non-aqueous electrolyte secondary battery additive is preferably 10 to 100% by weight based on the weight of the non-aqueous electrolyte secondary battery additive. Preferably it is 50 to 100% by weight.

  The additive for a non-aqueous electrolyte secondary battery of the present invention further includes other additives known to form SEI (vinylene carbonate, fluoroethylene carbonate, chloroethylene carbonate, ethylene sulfite, propylene sulfite, Propane sultone, α-bromo-γ-butyrolactone, and the like) may be contained, and the content thereof is preferably 0 to 50% by weight with respect to the compound (A).

  The electrode of the present invention is an electrode for a non-aqueous electrolyte secondary battery containing 0.05 to 5% by weight of the additive for a non-aqueous electrolyte secondary battery with respect to the total weight of the electrode.

In the electrode of the present invention, an electrode slurry is obtained by dispersing the above-mentioned additive for an non-aqueous electrolyte secondary battery, an active material, a binder, and, if necessary, a conductive additive in a solvent, and then the electrode slurry is collected into a current collector. It can obtain by drying an organic solvent after coating on top.
An electrode is classified into a positive electrode and a negative electrode, a positive electrode can be obtained by using a positive electrode active material as an active material, and a negative electrode can be obtained by using a negative electrode active material as an active material.

As the positive electrode active material, an oxide of lithium and a transition metal (for example, LiCoO ₂ , LiNiO ₂ and LiMn ₂ O ₄ ) or an oxide composed of a plurality of metal elements (for example, LiNi _1/3 Co _1/3 Mn _1/3) O ₂ , LiNi _5/12 Co _1/6 Mn _5/12 O ₂ , LiNi _8/10 Co _1/10 Mn _1/10 O ₂ and LiNi _0.8 Co _0.15 Al _0.05 ). .
Examples of the negative electrode active material include carbon-based materials such as natural graphite, artificial graphite, and amorphous carbon, and materials that form an alloy with lithium such as silicon and tin.

  Examples of the binder include polymer compounds such as starch, polyvinylidene fluoride, polyvinyl alcohol, carboxymethyl cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, and polypropylene.

  Optional conductive assistants include carbon blacks (eg carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black and thermal black) and metal powders (eg aluminum powder and nickel powder), conductive Metal oxides (for example, zinc oxide and titanium oxide).

  Examples of the solvent used when preparing the electrode of the present invention include water, N-methylpyrrolidone, acetone and toluene.

From the viewpoint of battery capacity, the content of the active material is preferably 70 to 98% by weight, more preferably based on the total weight of the active material, the binder, and the non-aqueous electrolyte secondary battery additive. 90 to 98% by weight.
The content of the binder is preferably 0.5 to 29% by weight based on the total weight of the active material, the binder, and the additive for the nonaqueous electrolyte secondary battery from the viewpoint of battery capacity. More preferably, it is 1 to 10% by weight.
From the viewpoint of high voltage cycle characteristics, the content of the additive for non-aqueous electrolyte secondary battery contained in the electrode of the present invention is that of the active material, binder, additive for non-aqueous electrolyte secondary battery. Based on the total weight, it is usually 0.05 to 5% by weight, preferably 0.1 to 1% by weight.
From the viewpoint of battery output, the content of the conductive assistant is preferably 0 to 29% by weight, more preferably based on the total weight of the active material, the binder, and the additive for the nonaqueous electrolyte secondary battery. Is 1 to 10% by weight.

  The electrolytic solution of the present invention is an electrolytic solution for a non-aqueous electrolyte secondary battery containing the additive for a non-aqueous electrolyte secondary battery in an amount of 0.05 to 5% by weight based on the total weight of the electrolytic solution.

  The electrolytic solution of the present invention contains the additive for a non-aqueous electrolyte secondary battery, an electrolyte, and a non-aqueous solvent. The electrolytic solution of the present invention can be obtained by dissolving the additive for non-aqueous electrolyte secondary battery and the electrolyte of the present invention in a non-aqueous solvent.

As the electrolyte, those used in ordinary non-aqueous electrolytes can be used, and lithium salts of inorganic acids such as LiPF ₆ , LiBF ₄ , LiSbF ₆ , LiAsF ₆ and LiClO ₄ , LiN (CF ₃ SO ₂ ). ₂ , lithium salts of organic acids such as LiN (C ₂ F ₅ SO ₂ ) ₂ and LiC (CF ₃ SO ₂ ) ₃ . Of these, lithium salts of inorganic acids are preferable from the viewpoint of battery characteristics, and LiPF ₆ is more preferable.

  As the non-aqueous solvent, those used for ordinary non-aqueous electrolytes can be used, such as lactone compounds, cyclic or chain carbonates, chain carboxylates, cyclic or chain ethers, phosphates, nitriles. Compounds, amide compounds, sulfones, sulfolanes and the like and mixtures thereof can be used.

Of the nonaqueous solvents, cyclic or chain carbonates are preferable from the viewpoint of battery output and charge / discharge cycle characteristics.
Examples of the cyclic carbonate include propylene carbonate, ethylene carbonate and butylene carbonate.
Examples of the chain carbonate include dimethyl carbonate, methyl ethyl carbonate, diethyl carbonate, methyl-n-propyl carbonate, ethyl-n-propyl carbonate, and di-n-propyl carbonate.

The content of the non-aqueous electrolyte secondary battery additive contained in the electrolytic solution of the present invention is such that the non-aqueous electrolyte secondary battery additive, the electrolyte, and the non-aqueous solvent are from the viewpoint of high voltage cycle characteristics and output characteristics. Based on the total weight, it is usually 0.05 to 5% by weight, preferably 0.1 to 1% by weight.
The content of the electrolyte is preferably 0.1 to 30% by weight, more preferably based on the total weight of the additive for the nonaqueous electrolyte secondary battery, the electrolyte, and the nonaqueous solvent from the viewpoint of battery characteristics. 0.5 to 20% by weight.
The content of the non-aqueous solvent is preferably 60 to 99% by weight based on the total weight of the non-aqueous electrolyte secondary battery additive, the electrolyte and the non-aqueous solvent from the viewpoint of battery output and charge / discharge cycle characteristics. Yes, more preferably 85 to 95% by weight.

  The non-aqueous electrolyte secondary battery of the present invention includes the above-mentioned additive for non-aqueous electrolyte secondary batteries.

Usually, a non-aqueous electrolyte secondary battery can be obtained by injecting an electrolyte into a battery can containing a positive electrode, a negative electrode, and a separator and sealing the battery can.
The non-aqueous electrolyte secondary battery of the present invention is a method using an electrode containing the additive for non-aqueous electrolyte secondary battery as a positive electrode and / or a negative electrode, and for the non-aqueous electrolyte secondary battery as an electrolytic solution. It can be obtained by a method using an electrolytic solution containing an additive, a method using a combination of the electrode and the electrolytic solution, or the like.

  The separator used in the non-aqueous electrolyte secondary battery of the present invention includes a microporous film made of polyethylene or polypropylene film, a multilayer film of porous polyethylene film and polypropylene, polyester fiber, aramid fiber, glass fiber, etc. In addition, there may be mentioned those in which ceramic fine particles such as silica, alumina and titania are adhered to the surface.

  As the battery can used for the non-aqueous electrolyte secondary battery of the present invention, metal materials such as stainless steel, iron, aluminum and nickel-plated steel can be used, but plastic materials can also be used depending on the battery application. . Further, the battery can can be formed into a cylindrical shape, a coin shape, a square shape, or any other shape depending on the application.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further, this invention is not limited to these. Hereinafter, unless otherwise specified, “%” represents “% by weight” and “parts” represents “parts by weight”.

<Production Example 1: Synthesis of Compound (A-1)>
In a flask equipped with a stirrer, a thermometer and a condenser, 6.1 parts of 2,2,2-trifluoroethanol (manufactured by Tokyo Chemical Industry Co., Ltd.), 5.8 parts of butyl isocyanate (Tokyo Chemical Industry Co., Ltd.) Manufactured), 100 parts of toluene (manufactured by Wako Pure Chemical Industries, Ltd.) and 0.1 part of tris (2-ethylhexanoic acid) bismuth (manufactured by Sigma-Aldrich) were charged and heated at 80 ° C. for 8 hours. Toluene was removed under reduced pressure (1.3 kPa) to obtain 11.0 parts of (A-1) represented by the chemical formula (4).

<Production Example 2: Synthesis of Compound (A-2)>
The reaction is performed in the same manner as in Production Example 1 except that 4.9 parts of hexamethylene diisocyanate (manufactured by Tokyo Chemical Industry Co., Ltd.) is used instead of 5.8 parts of butyl isocyanate. ) 10.2 parts were obtained. (A-2) was designated as battery additive (B-2).

<Production Example 3: Synthesis of Compound (A-3)>
The same process as in Production Example 1 was performed except that 9.7 parts of biuret-modified hexamethylene diisocyanate (Asahi Kasei Co., Ltd.) was used instead of 5.8 parts of butyl isocyanate. -3) 16.8 parts were obtained.

<Production Example 4: Synthesis of Compound (A-4)>
The same reaction as in Preparation Example 2 was conducted except that 2-fluoroethanol 3.9 (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 6.1 parts of 2,2,2-trifluoroethanol. 8.1 parts of a compound (A-4) represented by

<Production Example 5: Synthesis of compound (A-5)>
In place of 6.1 parts of 2,2,2-trifluoroethanol, 14.2 parts of 2,2,3,3,4,4,5,5-octafluoropentanol (manufactured by Tokyo Chemical Industry Co., Ltd.) Except having used, it carried out similarly to manufacture example 2 and obtained 17.5 parts of compounds (A-5) shown by the said Chemical formula (8).

<Production Example 6: Synthesis of Compound (A-6)>
Except for using 2.9 parts of 2,2,2-trifluoroethanol and 1.9 parts of methanol (manufactured by Tokyo Chemical Industry Co., Ltd.) instead of 6.1 parts of 2,2,2-trifluoroethanol. In the same manner as in Production Example 2, 9.3 parts of the compound (A-6) represented by the chemical formula (9) was obtained. (A-6) was designated as battery additive (B-6).

<Production Example 7: Synthesis of Compound (A-7)>
2. 3.9 parts of 2,2,3,3-tetrafluoro-1,4-butanediol (manufactured by Tokyo Chemical Industry Co., Ltd.), hexamethylene diisocyanate; 9 parts, 100 parts of toluene and 0.1 part of tris (2-ethylhexanoic acid) bismuth were charged and heated at 80 ° C. for 8 hours. Thereafter, 3.0 parts of 2,2,2-trifluoroethanol was added and further heated at 80 ° C. for 4 hours. Toluene was removed under reduced pressure (1.3 kPa) to obtain 9.3 parts of (A-7) represented by the chemical formula (10).

<Production Example 8: Synthesis of Compound (A-8)>
The same process as in Production Example 1 was conducted except that 6.5 parts of isophorone diisocyanate (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 5.8 parts of butyl isocyanate (A-8). 11.0 parts were obtained.

<Production Example 9: Synthesis of Compound (A-9)>
Except having used 13.0 parts of isophorone diisocyanate instead of 5.8 parts of butyl isocyanate, it carried out similarly to manufacture example 1, and obtained 17.8 parts of (A-8) shown by the said Chemical formula (12).

<Production Example 10: Synthesis of Compound (A-10)>
Similar to Production Example 1 except that 6.2 parts of 2,2,2-trifluoroamine (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 6.1 parts of 2,2,2-trifluoroethanol. And 10.3 parts of the compound (A-10) represented by the chemical formula (13) was obtained.

<Production Example 11: Synthesis of Compound (A-11)>
2.1 parts of methanol instead of 6.1 parts of 2,2,2-trifluoroethanol, 2,2,3,3,4,4,5,5-octafluoro instead of 4.9 parts of hexamethylene diisocyanate Except having used 9.1 parts of hexamethylene diisocyanate (Tokyo Chemical Industry Co., Ltd.), it carried out similarly to manufacture example 2 and obtained 10.1 parts of compounds (A-11) shown by the said Chemical formula (14). .

<Production Example 12>
2,2,3,3,4,4,5,5-octafluorohexamethylene diisocyanate (manufactured by Wako Pure Chemical Industries, Ltd.) represented by the chemical formula (15) was used as the compound (A-12).

<Production Example 13>
Comparative compound (A′-1) represented by the following chemical formula (11) was prepared in the same manner as in Production Example 1 except that 2.0 parts of methanol was used instead of 6.1 parts of 2,2,2-trifluoroethanol. 5.6 parts were obtained.

<Production Example 14>
The same reaction as in Production Example 6 was conducted except that 5.1 parts of 3-methyl-2-buten-1-ol (manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of 1.9 parts of methanol. 11.8 parts of a comparative compound (A′-2) represented by

  Group (a) contained in compounds (A-1) to (A-12) and Comparative compounds (A′-1) to (A′-2) obtained in Production Examples 1 to 14 and the alkyl fluoride Table 1 shows the type of the group (b1) or the fluorinated alkylene group (b2) and the presence or absence of a polymerizable unsaturated bond.

<Examples 1-15, Comparative Examples 1-5: Evaluation of Lithium Ion Batteries Using Electrodes Containing Nonaqueous Electrolyte Secondary Battery Additives>
The compounds (A-1) to (A-12) obtained in Production Examples 1 to 12 were directly used as additives for the non-aqueous electrolyte secondary battery of the present invention, and the compounds (A-1) to (A-12) were used. ) Were prepared by the following method, and a lithium ion battery was prepared and evaluated by the following method using the electrode. For comparison, the compounds (A′-1) and (A′-3), vinylene carbonate [compound (A′-3), manufactured by Kishida Chemical Co., Ltd.] and fluoro obtained in Production Examples 13 and 14 respectively. A comparative lithium ion battery was prepared and evaluated using ethylene carbonate [compound (A′-4), manufactured by Kishida Chemical Co., Ltd.].

[Production of Lithium Ion Battery Electrode (Positive Electrode) Containing Compound (A-1) to (A-12) or Comparative Compound (A′-1) to (A′-4)]
LiCoO2 powder [Nippon Chemical Industry Co., Ltd.] 90.0 parts, Kechen Black [Sigma Aldrich Co., Ltd.] 5 parts, polyvinylidene fluoride [Sigma Aldrich Co., Ltd.] 5 parts and Table 2 After thoroughly mixing parts of the compounds (A-1) to (A-12) and the comparative compounds (A′-1) to (A′-4) in a mortar, 1-methyl-2-pyrrolidone [Tokyo Kasei Co., Ltd.] Kogyo Co., Ltd.] 70.0 parts was added and further mixed well in a mortar to obtain a slurry. The obtained slurry was applied to one side of an aluminum electrolytic foil having a thickness of 20 μm using a wire bar in the air, dried at 80 ° C. for 1 hour, and further under reduced pressure (1.3 kPa) at 80 ° C. It was dried for 2 hours and punched out to 15.95 mmφ to produce a lithium ion battery electrode (positive electrode) used in Examples 1 to 3, Examples 5 to 15 and Comparative Examples 2 to 5.

[Preparation of Lithium Ion Battery Electrode (Positive Electrode) Containing neither Compound (A) nor Comparative Example Compound (A ′)]
90.0 parts of LiCoO2 powder [manufactured by Nippon Chemical Industry Co., Ltd.], 5 parts of Ketjen Black [manufactured by Sigma Aldrich Co., Ltd.] and 5 parts of polyvinylidene fluoride [manufactured by Sigma Aldrich Co., Ltd.] were thoroughly mixed in a mortar. Thereafter, 70.0 parts of 1-methyl-2-pyrrolidone [manufactured by Tokyo Chemical Industry Co., Ltd.] was added and further mixed well in a mortar to obtain a slurry. The obtained slurry was applied to one side of an aluminum electrolytic foil having a thickness of 20 μm using a wire bar in the air, dried at 80 ° C. for 1 hour, and further under reduced pressure (1.3 kPa) at 80 ° C. It was dried for 2 hours and punched out to 15.95 mmφ to produce lithium ion battery electrodes (positive electrodes) used in Examples 1 to 3 and Example 4.

[Preparation of Lithium Ion Battery Electrode (Negative Electrode) Containing Compound (A-1)]
92.5 parts of graphite powder [Sigma-Aldrich Co., Ltd.] 92.5 parts with an average particle size of about 8-12 μm, 2.5 parts of silicon powder [Sigma-Aldrich Co., Ltd.], polyvinylidene fluoride [Sigma-Aldrich Co., Ltd.] Product] 7.5 parts, 1-methyl-2-pyrrolidone [Tokyo Chemical Industry Co., Ltd.] 200 parts and the compound (A-1) shown in Table 2 were sufficiently mixed in a mortar to obtain a slurry. The obtained slurry was applied to one side of a 20 μm-thick copper foil in the air using a wire bar, dried at 80 ° C. for 1 hour, and further under reduced pressure (1.3 kPa) at 80 ° C. for 2 hours. It was dried, punched to 16.15 mmφ, and made 30 μm thick with a press machine to produce a lithium ion battery electrode (negative electrode) used in Example 4.

[Preparation of Lithium Ion Battery Electrode (Negative Electrode) Containing neither Compound (A) nor Comparative Example Compound (A ′)]
92.5 parts of graphite powder [Sigma-Aldrich Co., Ltd.] 92.5 parts with an average particle size of about 8 to 12 μm, 2.5 parts of silicon powder [Sigma-Aldrich Co., Ltd.], polyvinylidene fluoride [Sigma-Aldrich Co., Ltd.] 7 .5 parts, 200 parts of 1-methyl-2-pyrrolidone [manufactured by Tokyo Chemical Industry Co., Ltd.] were thoroughly mixed in a mortar to obtain a slurry. The obtained slurry was applied to one side of a 20 μm-thick copper foil in the air using a wire bar, dried at 80 ° C. for 1 hour, and further under reduced pressure (1.3 kPa) at 80 ° C. for 2 hours. It was dried, punched to 16.15 mmφ, and 30 μm thick with a press machine to produce lithium ion battery electrodes (negative electrodes) used in Examples 1-3, Examples 5-15, and Comparative Examples 2-5.

[Preparation of electrolyte for lithium ion battery]
LiPF ₆ (Morita) as an electrolyte so as to be 12% by weight in 87.5 parts of a mixed solvent (volume ratio 1: 1) of ethylene carbonate (manufactured by Kishida Chemical Co., Ltd.) and diethyl carbonate (manufactured by Kishida Chemical Co., Ltd.) Chemical Industries, Ltd.) was dissolved to prepare electrolytes used in Examples 1 to 15 and Comparative Examples 1 to 5.

[Production of lithium-ion batteries]
The positive electrode containing the compound (A) or (A ′) prepared above, the negative electrode containing the compound (A-1), and the positive electrode containing neither of the compounds (A) and (A ′) at both ends in the 2032 type coin cell. And the negative electrode is arranged with the combinations shown in Table 2 so that the respective coated surfaces face each other, a separator (polypropylene nonwoven fabric) is inserted between the electrodes, a lithium ion battery cell is prepared and inserted into a battery can, The electrolyte solution was poured and sealed to prepare a lithium ion battery for evaluation.
About the produced lithium ion battery, the charge / discharge cycle characteristic and the output characteristic were evaluated by the following methods, and the results are shown in Table 2.

<Evaluation of charge / discharge cycle characteristics>
Using a charge / discharge measuring device “Battery Analyzer 1470” [manufactured by Toyo Technica Co., Ltd.] at room temperature, the battery was charged to a voltage of 4.4 V with a current of 0.1 C, and after a pause of 10 minutes, 0.1 C The battery voltage was discharged to 3.0 V with the current of and this charge / discharge was repeated. At this time, the discharge capacity at the first charge / discharge and the discharge capacity at the 50th cycle charge / discharge were measured, and the charge / discharge cycle characteristics were calculated from the following formula. It shows that a high voltage charge / discharge cycle characteristic is so favorable that a numerical value is large.
High voltage charge / discharge cycle characteristics (%) = (discharge capacity at the 50th cycle discharge / discharge capacity at the first discharge) × 100

<Evaluation of output characteristics>
Using a charge / discharge measuring device “Battery Analyzer 1470” [manufactured by Toyo Technica Co., Ltd.] at room temperature, the battery was charged to a voltage of 4.4 V with a current of 0.1 C, and after a pause of 10 minutes, 0.1 C The battery voltage was discharged to 3.0 V at a current of 3 and this charge / discharge was repeated 3 times. The battery was charged again with a current of 0.1 C, discharged after a pause of 10 minutes, and discharged with a current of 1.0 C. The discharge capacity at 1.0 C discharge and the discharge capacity at the third cycle charge / discharge were measured, and the output characteristics were calculated from the following formula. The larger the value, the better the output characteristics.
Output characteristics (%) = (discharge capacity at 1.0 C discharge / discharge capacity at 0.1 C discharge at the third cycle) × 100

<Examples 16 to 26, Comparative Examples 6 to 10: Evaluation of Lithium Ion Batteries Using Electrolyte Solutions Containing Nonaqueous Electrolyte Secondary Battery Additives>
An electrolyte solution for a lithium ion battery containing the compounds (A-1) to (A-12) and the comparative example compounds (A′-1) to (A′-4) in the number of parts shown in Table 3 was obtained by the following method. The lithium ion battery was produced and evaluated by the following method using the electrolytic solution. Vinylene carbonate and fluoroethylene carbonate were used as the comparative compounds (A′-3) and (A′-4), respectively.

[Preparation of Lithium Ion Battery Electrolyte Solution Containing Compound (A-1) to (A-12) or Comparative Example Compound (A′-1) to (A′-4)]
87.5 parts of a mixed solvent of ethylene carbonate and diethyl carbonate (volume ratio 1: 1), the number of parts of compounds (A-1) to (A-12) shown in Table 3 and the comparative compound (A′-1) -(A'-4) was blended, and LiPF ₆ as an electrolyte was dissolved therein so as to be 12% by weight to prepare electrolytes used in Examples 16 to 26 and Comparative Examples 7 to 10.

[Production of lithium-ion batteries]
At both ends in the 2032 type coin cell, the coated surfaces of the positive electrode and the negative electrode, which do not contain any of the compounds (A) and (A ′) prepared above, are arranged facing each other, and a separator (polypropylene nonwoven fabric) is provided between the electrodes. Was inserted into a battery can, and an electrolyte for a lithium ion battery containing the compound (A) or the comparative compound (A ′) prepared above was injected into the battery can. After sealing, a lithium ion battery for evaluation was produced.
Further, the charge / discharge cycle characteristics and output characteristics were evaluated in the same manner as described above, and the results are shown in Table 3. In Comparative Example 6, the electrolytic solution used in Examples 1 to 15 was used.

  From Examples 1 to 26 and Comparative Examples 1 to 10, it was found that the nonaqueous electrolyte secondary battery containing the compound (A) was excellent in charge / discharge cycle characteristics and output characteristics. This is presumably because the compound (A) formed unique SEI on the electrode surface and suppressed redox decomposition of the electrolytic solution. In Comparative Examples 3 and 8 having the comparative compound (A′-2), the cycle characteristics were good, but the output characteristics were deteriorated. This is presumably because the SEI thickness increased due to the presence of polymerizable unsaturated bonds, and the ionic conductivity deteriorated.

  Since the nonaqueous electrolyte secondary battery containing the additive for nonaqueous electrolyte secondary batteries of the present invention has high cycle characteristics, it is suitable as a power source for portable electronic devices such as mobile phones and smartphones. Moreover, since it has high output characteristics, it is also suitable for electric vehicle applications.

Claims (6)

At least one hydrogen atom among hydrogen atoms of at least one group (a) selected from the group consisting of a urethane group, a urea group, an allophanate group, a biuret group, and an isocyanate group and an alkyl group having 2 to 20 carbon atoms is A fluorinated alkylene group (b2) in which at least one hydrogen atom among the hydrogen atoms of the fluorinated alkyl group (b1) substituted with a fluorine atom and / or an alkylene group having 2 to 20 carbon atoms is substituted with a fluorine atom; An additive for a non-aqueous electrolyte secondary battery comprising a non-addition polymerizable compound (A) having: The additive for nonaqueous electrolyte secondary batteries according to claim 1, wherein the non-addition polymerizable compound (A) is represented by the following general formula (1).
[In General Formula (1), R ¹ is a residue obtained by removing all isocyanate groups from an m-valent isocyanate compound which may have a fluorine atom, and X ¹ is represented by the following General Formula (2). A monovalent group or an isocyanate group, m is an integer of 1 to 6, and when m is 1 or 2, at least one of X ¹ and R ¹ is a group having a fluorine atom, and m is In the case of an integer of 3 to 6, X ¹ is a group having a fluorine atom, and when m is an integer of 2 to 6, a plurality of X ¹ may be the same or different. ]
[In General Formula (2), R ² is the fluorinated alkyl group (b1) or a monovalent hydrocarbon group having no fluorine atom having 1 to 20 carbon atoms, and Z ¹ is an oxygen atom or an imino group. Yes, and * ¹ represents that it is bonded to R ¹ in the general formula (1) by the bond to which it is attached. ] The additive for a non-aqueous electrolyte secondary battery according to claim 2, wherein m is 2 and R ¹ is a divalent group represented by the following general formula (3) in the general formula (1).
[In General Formula (3), R ³ , R ⁵ and R ⁷ are each a residue obtained by removing an isocyanate group from a C 4-20 diisocyanate compound, each having a fluorine atom, and R ⁴ and R ⁶ is independently a fluorinated alkylene group in which at least one hydrogen atom is substituted with a fluorine atom among hydrogen atoms of an alkylene group having 2 to 20 carbon atoms, or 2 having 1 to 20 carbon atoms not having a fluorine atom. Is a valent hydrocarbon group, k is an integer of 1 to 10, Z ^{2 to} Z ⁵ are each independently an oxygen atom or an imino group, and at least one of R ^{3 to} R ⁷ is a fluorine atom. * ² represents that it is bonded to X ¹ in the general formula (1) by the bond to which it is attached. ]   The electrode for nonaqueous electrolyte secondary batteries which contains 0.05 to 5weight% of the additive for nonaqueous electrolyte secondary batteries of any one of Claims 1-3 with respect to the total weight of an electrode .   Electrolysis for nonaqueous electrolyte secondary batteries containing 0.05 to 5 wt% of the additive for nonaqueous electrolyte secondary batteries according to any one of claims 1 to 3 with respect to the total weight of the electrolyte. liquid.   The nonaqueous electrolyte secondary battery containing the additive for nonaqueous electrolyte secondary batteries of any one of Claims 1-3.