JP6642081B2 - Polymer compound, binder for negative electrode, intermediate composition, negative electrode, power storage device, slurry for negative electrode, method for producing polymer compound, and method for producing negative electrode - Google Patents

Description

The present invention is a high molecular compound, an intermediate composition of the negative electrode binder, polymer compound used as a negative electrode binder, a negative electrode, a power storage device, the negative electrode slurry, a method of manufacturing a polymer compound, and a manufacturing method of the negative electrode About.

  Products using secondary batteries are steadily increasing, and secondary batteries are frequently used in portable devices such as mobile phones and notebook computers. Also, secondary batteries have attracted attention as large power sources for electric vehicles.

  By the way, the electrode of the secondary battery is composed of, for example, a current collector formed of a metal material such as copper or aluminum, and an active material layer bound on the current collector. The active material layer generally contains an electrode binder (binder) for binding the active material to the current collector. In recent years, attempts have been made to use polyacrylic acid, which is an inexpensive polymer compound, as the electrode binder. For example, Patent Literature 1 discloses an electrode binder including lithium polyacrylate and sodium polyacrylate. Patent Literature 2 discloses an electrode binder including polyacrylic acid and polyethyleneimine. Patent Literature 3 discloses an electrode binder containing polyacrylic acid and an amine compound.

JP 2009-080971 A JP 2009-135103 A JP-A-2003-003031

  As a result of diligent research by the present researchers, a polymer compound obtained by condensing polyacrylic acid, a polyfunctional amine having a specific molecular structure, and a polyfunctional carboxylic acid having a cyclic molecular structure, into a secondary battery It has been found that the use as a binder for a negative electrode of a power storage device improves the adhesiveness of a negative electrode active material layer.

An object of the present invention is to provide a polymer compound that can improve the adhesion of a negative electrode active material layer when used as a binder for a negative electrode of a power storage device, and to improve the adhesion of a negative electrode active material layer. It is an object of the present invention to provide a binder for a negative electrode that can be used , and to provide an intermediate composition for obtaining a polymer compound used as a binder for a negative electrode . Another object of the present invention is to provide a negative electrode, a power storage device, and a slurry for the negative electrode using the polymer compound as a negative electrode binder. Another object is to provide a method for producing the polymer compound and a method for producing a negative electrode.

The invention of claim 1 has a chain structure constituted by Po Riakuriru acid, and a cross-linked structure that connects the carboxylic acid side chain with each other between the chain-like structure in or chain structure, said bridge structure Is characterized by being at least one kind of crosslinked structure selected from the following general formulas (2) to (4).

(PAA indicates a chain structure composed of polyacrylic acid, and X is a structure represented by the following general formula (5).)

(Y is a linear alkyl group having 1 to 4 carbon atoms, a phenylene group, or an oxygen atom, and R1 and R2 are each independently a single or plural hydrogen atoms, a methyl group, an ethyl group, a trifluoromethyl group. Or a methoxy group, Z is a cyclic structure having a carbon skeleton, A1 and A2 are each independently a hydrogen atom or a carbonyl carbon, and n is an integer of 1 to 5.)
The invention according to claim 2 is the polymer compound according to claim 1 , wherein Z in the crosslinked structure is a polycyclic ring structure in which a ring structure having two or more carbon skeletons is linked. Features.
According to a third aspect of the present invention, there is provided a negative electrode binder for a power storage device, comprising the polymer compound according to the first or second aspect.

The invention according to claim 4 is an intermediate composition of a polymer compound used as the binder for a negative electrode according to claim 3 , wherein polyacrylic acid, a polyfunctional amine represented by the following general formula (1), It contains a polyfunctional carboxylic acid having a cyclic molecular structure, and a non-aqueous solvent, to name a liquid, the mixing ratio of the polyfunctional carboxylic acid to polyfunctional amine (polyfunctional carboxylic acid / polyfunctional amine) 0 .14 or less .

(Y is a linear alkyl group having 1 to 4 carbon atoms, a phenylene group, or an oxygen atom, and R1 and R2 are each independently a single or plural hydrogen atoms, a methyl group, an ethyl group, a trifluoromethyl group. Or a methoxy group.)
The invention according to claim 5 is an intermediate composition of a polymer compound used as the binder for a negative electrode according to claim 3, wherein polyacrylic acid, a polyfunctional amine represented by the following general formula (1), It contains a polyfunctional carboxylic acid having a cyclic molecular structure and a non-aqueous solvent and is in a liquid form, and the polyfunctional carboxylic acid is a polyfunctional carboxylic acid having a linked cyclic structure comprising two or more carbon skeletons having a carboxyl group. It is characterized by being at least one selected from carboxylic acids and polyfunctional carboxylic acids having an asymmetric molecular structure.
(Y is a linear alkyl group having 1 to 4 carbon atoms, a phenylene group, or an oxygen atom, and R1 and R2 are each independently a single or plural hydrogen atoms, a methyl group, an ethyl group, a trifluoromethyl group. Or a methoxy group.)
According to a sixth aspect of the present invention, in the intermediate composition according to the fourth or fifth aspect, the polyfunctional carboxylic acid has a polycyclic structure in which a cyclic structure composed of two or more carbon skeletons having a carboxyl group is connected. It is a polyfunctional carboxylic acid of the formula.

The invention according to claim 7 is the method for producing a polymer compound according to claim 1 or 2 , wherein polyacrylic acid, a polyfunctional amine represented by the following general formula (1), and a cyclic molecule The method is characterized in that the polyfunctional carboxylic acid having a structure is heated at a temperature of 150C to 230C.

(Y is a linear alkyl group having 1 to 4 carbon atoms, a phenylene group, or an oxygen atom, and R1 and R2 are each independently a single or plural hydrogen atoms, a methyl group, an ethyl group, a trifluoromethyl group. Or a methoxy group.)
According to an eighth aspect of the present invention, in the method for producing a polymer compound according to the seventh aspect, an intermediate containing the polyacrylic acid, the polyfunctional amine, the polyfunctional carboxylic acid, and a non-aqueous solvent. The method is characterized in that the composition is pre-heated at a temperature of 40C to 140C and then heated at a temperature of 150C to 230C.

According to a ninth aspect of the present invention, there is provided a negative electrode of a power storage device, comprising: the negative electrode binder according to the third aspect; and a negative electrode active material, wherein the negative electrode active material is a carbon capable of occluding and releasing lithium. It is characterized by containing at least one selected from a system material, an element capable of being alloyed with lithium, and a compound having an element capable of being alloyed with lithium.

The invention according to claim 10, in the negative electrode according to claim 9, wherein the negative electrode active material, silicon material obtained through the decalcified reaction from CaSi _2, Si, and _SiO V (0 <v ≦ 2 ) Is at least one selected from the group consisting of:

A power storage device according to an eleventh aspect of the present invention includes the negative electrode according to the ninth or tenth aspect and a non-aqueous electrolyte.
The invention according to claim 12 is a slurry for a negative electrode used for manufacturing a negative electrode of a power storage device, the intermediate composition according to any one of claims 4 to 6 , a negative electrode active material, Containing a solvent, and as the negative electrode active material, containing at least one selected from a carbon-based material capable of inserting and extracting lithium, an element capable of being alloyed with lithium, and a compound having an element capable of being alloyed with lithium. It is characterized by the following.

  According to a thirteenth aspect of the present invention, there is provided a method for manufacturing a negative electrode of a power storage device, wherein the negative electrode active material layer is formed on a current collector using the negative electrode slurry according to the twelfth aspect. Features.

According to a fourteenth aspect of the present invention, in the method for producing a negative electrode according to the thirteenth aspect, the slurry for the negative electrode includes a silicon material obtained through a decalcification reaction from CaSi ₂ as the negative electrode active material; , And SiO _V (0 < v ≦ 2).

  According to the present invention, the adhesion of the negative electrode active material layer can be improved.

Hereinafter, embodiments embodying the present invention will be described in detail.
The polymer compound of the present embodiment is a polymer compound obtained by condensing (A) polyacrylic acid, (B) a polyfunctional amine, and (C) a polyfunctional carboxylic acid.

  (A) Polyacrylic acid is a homopolymer having acrylic acid as a constituent unit. The weight average molecular weight of the polyacrylic acid is not particularly limited, but is preferably, for example, in the range of 10,000 to 2,000,000, and in the range of 25,000 to 1,800,000. More preferably, it is still more preferably in the range of 50,000 to 1,500,000.

  (B) The polyfunctional amine is a compound having a structure represented by the following general formula (1).

In the general formula (1), Y is a linear alkyl group having 1 to 4 carbon atoms, a phenylene group, or an oxygen atom. The bonding position of Y in each benzene ring may be any of the ortho, meta, and para positions with respect to the amino group.

  When Y is a linear alkyl group or a phenylene group, a substituent may be bonded to a carbon atom constituting the structure. For example, examples of the substituent bonded to the carbon atom constituting the linear alkyl group include a methyl group, an ethyl group, a fluoromethyl group, a difluoromethyl group, a trifluoromethyl group, a methoxy group, an ethoxy group, and an oxo group. . Only one of these substituents may be bonded, or two or more thereof may be bonded. Further, the number of substituents bonded to one carbon atom may be one or two. Further, the substituent bonded to the carbon atom constituting the straight-chain alkyl group and the phenylene group may be an amino group or a substituent containing an amino group. In this case, the substituent has three or more amino groups. It becomes a polyfunctional amine.

  In the general formula (1), R1 and R2 are each independently a single or plural hydrogen atoms, a methyl group, an ethyl group, a trifluoromethyl group, or a methoxy group. When R1 is a methyl group, an ethyl group, a trifluoromethyl group, or a methoxy group, the bonding position of R1 may be any of the ortho, meta, and para positions with respect to the amino group. The same applies to R2.

(B) Specific examples of the polyfunctional amine will be described.
Examples of the polyfunctional amine in which Y is a linear alkyl group include 3,3′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane, 4,4′-ethylenedianiline, , 4'-Diamino-3,3'-dimethyldiphenylmethane, 1,1-bis (4-aminophenyl) cyclohexane, 9,9-bis (4-aminophenyl) fluorene, 2,2'-bis (4-amino Phenyl) hexafluoropropane, 4,4'-diaminobenzophenone, 4,4'-methylenebis (2-ethyl-6-methylaniline), and pararoseaniline.

  Examples of the polyfunctional amine in which Y is a phenylene group include 1,3,5-tris (4-aminophenyl) benzene. Examples of the polyfunctional amine in which Y is an oxygen atom include 4,4'-diaminodiphenyl ether. In addition, 1,3,5-tris (4-aminophenyl) benzene and pararoseaniline are trifunctional amines having three amino groups. One of the above polyfunctional amines may be used alone, or two or more may be used in combination.

  The blending ratio of (B) the polyfunctional amine is set according to the number of amino groups of the (B) polyfunctional amine. That is, the mixing ratio is set so that the number of carboxyl groups in (A) polyacrylic acid is larger than the number of amino groups in (B) the polyfunctional amine. In other words, the mixing ratio is set such that the carboxyl group in (A) polyacrylic acid is 1 equivalent or more with respect to 1 equivalent of amino group in (B) polyfunctional amine. The ratio (carboxyl group / amino group ratio) between (A) the number of carboxyl groups of polyacrylic acid and (B) the number of amino groups of the polyfunctional amine is preferably in the range of 1 to 15, and is preferably 3 to 15. More preferably, it is in the range of 10 to 10.

(C) The polyfunctional carboxylic acid is a compound having a cyclic structure having a carbon skeleton in a molecular structure, and two or more carboxyl groups bonded to the cyclic structure.
Examples of the cyclic structure having a carbon skeleton include, for example, a 4-membered to 8-membered monocyclic structure and a polycyclic structure in which a plurality of (for example, 2 to 3) 4- to 8-membered rings are combined. Cyclic structures. By employing a structure having four or more rings (the number of atoms constituting the ring is four or more), decomposition of the polyfunctional carboxylic acid during heat treatment is suppressed. By employing a structure having an eight-membered ring or less, the effect of suppressing thermal shrinkage of the polymer compound is suppressed from being reduced due to too large movement of the ring.

  The cyclic structure composed of a carbon skeleton may be a cyclic structure composed only of carbon atoms (carbocyclic structure) or a cyclic structure composed of carbon atoms and other atoms (heterocyclic structure). . Further, a substituent may be bonded to the cyclic structure having a carbon skeleton.

The carboxyl group bonded to the cyclic structure having a carbon skeleton may be one or more acid anhydride structures.
Further, the polycyclic ring structure may be a fused polycyclic ring structure in which some atoms constituting the ring structure are shared among a plurality of ring structures, or two or more ring structures. It may be a linked polycyclic ring structure in which the structures are linked. When a polyfunctional carboxylic acid having a fused polycyclic structure is used, the effect of improving the adhesiveness of the negative electrode active material layer becomes greater.

  Further, among the polyfunctional carboxylic acids having a linked polycyclic cyclic structure, a polyfunctional carboxylic acid having a linked cyclic structure composed of two or more carbon skeletons having a carboxyl group is preferable. In a polyfunctional carboxylic acid in which a cyclic structure composed of two or more carbon skeletons having a carboxyl group is linked, the cyclic structures may be directly linked, or may be linked via a specific linking structure, More preferably, they are connected via a specific connection structure. When connected via a specific connection structure, the flexibility of the structural portion is increased. Specific connection structure, for example, a linear or branched alkyl group, an alkenyl group, a carbon chain having 1 to 4 carbon atoms such as an alkynyl group, an oxygen atom, a sulfur atom, a sulfonyl group, a phenylene group, and a combination thereof. No. Further, a substituent may be bonded to these linking structures.

  (C) Specific examples of the polyfunctional carboxylic acid include phthalic acid, trimellitic acid, pyromellitic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,3,5-cyclohexanetricarboxylic acid, 1,2,4 and 5-cyclohexanetetracarboxylic acid, 1,2,3,4,5,6-cyclohexanehexacarboxylic acid, 1,3-adamantanedicarboxylic acid, 1,2-cyclopentanedicarboxylic acid, 1,3-cyclopentanedicarboxylic acid, 1,1,3-cyclopentanetricarboxylic acid, 1,2,4-cyclopentanetricarboxylic acid, 1,3,4-cyclopentanetricarboxylic acid, 2,3,4,5-tetrahydrofurantetracarboxylic acid, bicyclo [2. 2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride.

  Specific examples of the polyfunctional carboxylic acid having a fused polycyclic ring structure include 1,4-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 3,4,9 , 10-Perylenetetracarboxylic dianhydride.

  Specific examples of the polyfunctional carboxylic acid in which a cyclic structure composed of two or more carbon skeletons having a carboxyl group are directly linked include 2,2′-biphenyldicarboxylic acid, 3,3′-biphenyldicarboxylic acid, 4,4 '-Biphenyldicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, and 4,4'-biphthalic anhydride.

  Specific examples of the polyfunctional carboxylic acid in which cyclic structures having a carbon skeleton are linked to each other via a specific linking structure include 3,3 ′, 4,4′-benzophenonetetracarboxylic anhydride and 4,4′- Oxydiphthalic anhydride, 3,4′-oxydiphthalic acid, 4,4 ′-(ethyne-1,2-diyl) diphthalic anhydride, 4,4 ′-(hexafluoroisopropylidene) diphthalic anhydride, 4, 4 '-(4,4'-isopropylidene diphenoxy) diphthalic anhydride and 3,3', 4,4'-diphenylsulfonetetracarboxylic anhydride.

One of the above polyfunctional carboxylic acids may be used alone, or two or more may be used in combination.
The mixing ratio of the (C) polyfunctional carboxylic acid is, in molar ratio, the ratio of (B) the polyfunctional amine to the (C) polyfunctional carboxylic acid (the number of amino groups of the polyfunctional amine / the carboxyl group of the polyfunctional carboxylic acid Is preferably in the range of 7 to 25, and more preferably in the range of 5 to 15.

  In the molar ratio of (C) the polyfunctional carboxylic acid, the ratio (mol number of polyfunctional carboxylic acid / mol number of polyfunctional amine) to (B) polyfunctional amine is 0.05 or more. It is more preferably 0.15 or more. The upper limit of the above ratio is, for example, 1.2. As the ratio is set higher, the cycle characteristics of the power storage device improve, while the polyfunctional carboxylic acid tends to crystallize during preparation. Therefore, the ratio is preferably set to a high value within a range where the polyfunctional carboxylic acid does not crystallize during preparation.

  In addition, a polyfunctional carboxylic acid having a cyclic structure composed of two or more carbon skeletons having a carboxyl group and a polyfunctional carboxylic acid having an asymmetric molecular structure such as trimellitic acid (trimellitic anhydride) are other The crystallization hardly occurs as compared with the above polyfunctional carboxylic acid, and the above ratio can be set to a higher value. Therefore, the cycle characteristics of the power storage device can be further improved.

  The polymer compound of the present embodiment includes a mixing step of mixing (A) polyacrylic acid, (B) a polyfunctional amine, and (C) a polyfunctional carboxylic acid in a solvent, and an intermediate composition obtained in the mixing step. And a heating step of heating the product.

  The mixing step is a step of obtaining a liquid intermediate composition formed by mixing (A) polyacrylic acid, (B) a polyfunctional amine, (C) a polyfunctional carboxylic acid, and a solvent. As the solvent used in the mixing step, a solvent in which (A) polyacrylic acid, (B) a polyfunctional amine, and (C) a polyfunctional carboxylic acid can be appropriately selected and used. In particular, from the viewpoint of improving solubility, it is preferable to use a non-aqueous solvent such as N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, dimethylsulfoxide, propylene carbonate, γ-butyrolactone, ethanol, and propanol.

  The heating step is a step of subjecting the intermediate composition to a heat treatment to condense the polyacrylic acid (A), the polyfunctional amine (B), and the polyfunctional carboxylic acid (C) contained in the intermediate composition. The heating temperature in the heating step is preferably in the range of 150 to 230 ° C, and more preferably 180 to 200 ° C, from the viewpoint of promoting formation of a crosslinked structure, that is, from the viewpoint of efficient formation of an amide bond or an imide bond. More preferably, it is within the range.

  When heating the intermediate composition, a catalyst may be added to the intermediate composition in order to promote a condensation reaction for forming an amide bond and an imide bond or to increase the reaction rate of the condensation reaction. Examples of the catalyst include 1-methylimidazole, 2-methylimidazole, N, N′-dicyclohexylcarbodiimide, N, N′-carbonyldiimidazole, N, N′-diisopropylcarbodiimide, 1- [3- (dimethylamino) ) Propyl] -3-ethylcarbodiimide, 1-ethyl-3- (3-dimethylaminopropyl) carbodiimide hydrochloride, diphenylphosphoric acid azide, a dehydration condensation catalyst such as a BOP reagent can be suitably used.

  Note that the intermediate composition to be subjected to the heating step is preferably an intermediate composition that has been preheated. The temperature of the preheating treatment is preferably in the range of 40 to 140C, more preferably in the range of 60 to 130C. By performing the preheating treatment, the polyacrylic acid (A), the polyfunctional amine (B), and the polyfunctional carboxylic acid (C) contained in the intermediate composition associate to form a condensation reaction between the carboxyl group and the amino group. Is formed in a state in which progress is easy. As a result, in the heating step, the condensation reaction can proceed efficiently. By the preheating treatment, the condensation reaction between the carboxyl group and the amino group partially proceeds, and an amide bond or an imide bond may be formed.

  In the case of using the intermediate composition that has been subjected to the preliminary heat treatment, the heating step is preferably performed in a state where the solvent contained in the intermediate composition has been removed. In this case, the condensation reaction of (A) polyacrylic acid, (B) polyfunctional amine, and (C) polyfunctional carboxylic acid easily proceeds.

  Then, through a heating step, a polymer compound obtained by condensation of (A) polyacrylic acid, (B) polyfunctional amine and (C) polyfunctional carboxylic acid is obtained. In this polymer compound, an amide bond or an imide bond is formed between (A) a carboxyl group of polyacrylic acid and (B) an amino group of a polyfunctional amine, and (B) an amino group of the polyfunctional amine and It is considered that an amide bond or an imide bond is formed between (C) the carboxyl group of the polyfunctional carboxylic acid and (A) the polyacrylic acid has a crosslinked structure. That is, the polymer compound has a chain structure composed of polyacrylic acid and a crosslinked structure that connects carboxylic acid side chains within the chain structure or between the chain structures. The crosslinked structure is at least one type of crosslinked structure selected from the following general formulas (2) to (4).

In the general formulas (2) to (4), PAA indicates a chain structure composed of polyacrylic acid. X has a structure represented by the following general formula (5). In the general formulas (3) and (4) having an imide structure, the two carbonyl groups constituting one imide structure may be carbonyl groups bonded to different chain structures, or may be the same. It may be a carbonyl group bonded to a chain structure. For example, when the two carbokinyl groups constituting the imide structure are carbonyl groups bonded to adjacent carbons in the same chain structure, a maleimide structure is formed as the imide structure.

In the general formula (5), Y is a linear alkyl group having 1 to 4 carbon atoms, a phenylene group, or an oxygen atom. The bonding position of Y in each benzene ring may be any of the ortho, meta, and para positions with respect to the amino group. Note that Y in the general formula (5) has a structure similar to Y in the general formula (1).

  In the general formula (5), R1 and R2 are each independently a single or plural hydrogen atoms, a methyl group, an ethyl group, a trifluoromethyl group, or a methoxy group. When R1 is a methyl group, an ethyl group, a trifluoromethyl group, or a methoxy group, the bonding position of R1 may be any of the ortho, meta, and para positions with respect to the amino group. The same applies to R2. Note that R1 and R2 in the general formula (5) have a structure similar to R1 and R2 in the general formula (1).

  In the general formula (5), Z is a cyclic structure having a carbon skeleton. Examples of the cyclic structure having a carbon skeleton include, for example, a 4-membered to 8-membered monocyclic structure and a polycyclic structure in which a plurality of 4-membered to 8-membered rings are combined. The polycyclic ring structure may be a fused polycyclic ring structure in which some atoms constituting the ring structure are shared among a plurality of ring structures, or two or more ring structures may be used. It may have a linked polycyclic ring structure. In the case of a fused polycyclic structure, the effect of improving the adhesiveness of the negative electrode active material layer becomes greater.

  Further, in the connection type polycyclic ring structure, a structure in which a ring structure having two or more carbon skeletons is preferably connected. In a structure in which two or more carbon skeletons are connected to each other, the cyclic structures may be directly connected to each other or may be connected to each other via a specific connection structure. More preferably, they are connected. When connected via a specific connection structure, the flexibility of the structural portion is increased. Examples of the specific linking structure include a carbon chain having 1 to 4 carbon atoms such as a linear or branched alkyl group, alkenyl group, and alkynyl group, an oxygen atom, a sulfur atom, a phenylene group, and a combination thereof. Further, a substituent may be bonded to these linking structures.

  The cyclic structure composed of a carbon skeleton may be a cyclic structure composed only of carbon atoms (carbocyclic structure) or a cyclic structure composed of carbon atoms and other atoms (heterocyclic structure). . Further, a substituent may be bonded to the cyclic structure having a carbon skeleton. Note that Z in the general formula (5) has a structure according to the polyfunctional carboxylic acid (C).

  In the general formula (5), A1 and A2 are each independently a hydrogen atom or a carbonyl carbon. When A1 is a hydrogen atom, the nitrogen atom bonded to A1 forms an amide structure, and when A1 is a carbonyl carbon, the nitrogen atom bonded to A1 forms an imide structure. The same applies to A2. In addition, carbonyl carbon derived from polyacrylic acid and carbonyl carbon derived from polyfunctional carboxylic acid correspond to the carbonyl carbon. The carbonyl carbon derived from the polyfunctional carboxylic acid may be a carbonyl carbon constituting a portion represented by the general formula (5) in the crosslinked structure of the general formulas (2) to (4). That is, a structure in which the crosslinked structures are connected in a mesh shape may be used.

In the general formula (5), n is an integer of 1 to 5.
The polymer compound preferably has both an amide bond and an imide bond in its crosslinked structure. That is, it is preferable that the crosslinked structure has at least the crosslinked structures of the general formulas (2) and (4), or at least the crosslinked structure of the general formula (3).

  Further, the polymer compound may have an acid anhydride structure (CO—O—CO) formed by dehydration condensation of two carboxyl groups in the molecular structure. The acid anhydride structure may be a structure formed in the same chain structure (PAA) or may be a structure formed between different chain structures (PAA). That is, two carbonyl carbons contained in the acid anhydride structure may be bonded to the same chain structure (PAA) or may be bonded to different chain structures (PAA).

  Further, the polymer compound of the present embodiment may further have another crosslinked structure other than the structure represented by the general formula (5). Examples of other crosslinked structures include a crosslinked structure in which “n = 0” in the general formula (5) and a crosslinked structure derived from other polyfunctional amines that do not correspond to the general formula (1). By adding another crosslinked structure, physical properties such as strength and flexibility of the polymer compound can be adjusted.

  In addition, as other polyfunctional amines, for example, 1,4-diaminobutane, 1,6-diaminohexane, 1,8-diaminooctane, 2-aminoaniline (1,2-phenylenediamine), 3-aminoaniline (1,3-phenylenediamine), 4-aminoaniline (1,4-phenylenediamine), 2,4-diaminopyridine, 2,5-diaminopyridine, 2,6-diaminopyridine, 1,3-diiminoiso And indoline.

Next, an example of a method for producing a negative electrode using the polymer compound of the present embodiment as a negative electrode binder will be described.
First, a negative electrode active material, a negative electrode binder, and a solvent are mixed to prepare a slurry. At that time, other components such as a conductive additive may be further mixed as necessary.

  As the negative electrode active material, a known material used as a negative electrode active material of a power storage device such as a secondary battery, for example, a carbon-based material, an element capable of being alloyed with lithium, and a compound including an element capable of being alloyed with lithium. Can be used.

  As the carbon-based material, for example, a carbon-based material capable of inserting and extracting lithium can be used. Specific examples thereof include non-graphitizable carbon, natural graphite, artificial graphite, cokes, graphites, and glassy materials. Carbons, fired organic polymer compounds, carbon fibers, activated carbon, and carbon blacks may be mentioned.

  Elements that can be alloyed with lithium include, for example, Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Ti, Ag, Zn, Cd, Al, Ga, In, Si, Ge, Sn, Pb, Sb and Bi are mentioned. Of these, Si is particularly preferred.

  Examples of the compound having an element that can be alloyed with lithium include Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Ba, Ra, Ti, Ag, Zn, Cd, Al, Ga, and In. , Si, Ge, Sn, Pb, Sb, and a compound having an element selected from Bi. Among these, a silicon-based material that is a compound having Si is particularly preferable.

Examples of the silicon-based material include SiB ₄ , SiB ₆ , Mg ₂ Si, Ni ₂ Si, TiSi ₂ , MoSi ₂ , CoSi ₂ , NiSi ₂ , CaSi ₂ , CrSi ₂ , Cu ₅ Si, FeSi ₂ , MnSi ₂ , NbSi ₂ , TaSi ₂ , VSi ₂ , WSi ₂ , ZnSi ₂ , SiC, Si ₃ N ₄ , Si ₂ N ₂ O, SiO _V (0 <V ≦ 2), SnSiO ₃ , and LiSiO. Among them, SiO _V (0 <V ≦ 2) is particularly preferable.

Further, as the silicon-based material, a silicon material obtained through a decalcification reaction from CaSi ₂ disclosed in International Publication No. 2014/080608 can also be used. The silicon material is, for example, a silicon material obtained by subjecting a layered polysilane obtained by treating CaSi ₂ to an acid (for example, hydrochloric acid or hydrogen fluoride) to decalcification (for example, a heat treatment at 300 to 1000 ° C.). It is. The polymer compound of the present embodiment is particularly preferably used in combination with a silicon-based material that is a negative electrode active material having a large degree of expansion and contraction during charge and discharge. Note that as the negative electrode active material, only one of the above substances may be used, or two or more of the above substances may be used in combination.

The above-mentioned intermediate composition is used as a binder for a negative electrode mixed with the slurry.
Further, another binder for the negative electrode may be used in combination as the binder for the negative electrode. As other negative electrode binders, for example, polyvinylidene fluoride, polytetrafluoroethylene, styrene-butadiene rubber, polyimide, polyamideimide, carboxymethylcellulose, polyvinyl chloride, methacrylic resin, polyacrylonitrile, modified polyphenylene oxide, polyethylene oxide, Examples include polyethylene, polypropylene, polyacrylic acid, and phenol resin.

  Further, as another negative electrode binder, a polymer compound obtained by condensation of polyacrylic acid and a polyfunctional amine having a structure represented by the general formula (1), that is, a chain structure composed of polyacrylic acid, and a general formula ( In 5), a polymer compound having a crosslinked structure where “n = 0” may be used.

  Among these other negative electrode binders, only one kind may be used in combination, or two or more kinds may be used in combination. When another binder for a negative electrode is used in combination, the solid content of the intermediate composition is preferably 1% by mass or more, preferably 10% by mass or more, based on the total solid content of the negative electrode binder. Is more preferable.

  The mixing ratio (negative electrode active material: negative electrode binder) in the mass ratio between the negative electrode active material and the negative electrode binder can be appropriately set according to the types of the negative electrode active material and the negative electrode binder. The compounding ratio is, for example, preferably in the range of 5: 3 to 99: 1, more preferably in the range of 3: 1 to 97: 3, and in the range of 16: 3 to 95: 5. Is more preferred.

  As the solvent, a known solvent used at the time of manufacturing an electrode of a power storage device such as a secondary battery can be used as appropriate depending on the types of the negative electrode active material and the negative electrode binder. Specific examples of the solvent include N-methyl-2-pyrrolidone, methanol, and methyl isobutyl ketone.

  As the conductive additive, a known conductive additive used for a negative electrode of a power storage device such as a secondary battery can be used. Specific examples of the conductive additive include acetylene black, carbon nanotube, and Ketjen black. Among these conductive assistants, only one kind may be used, or two or more kinds may be used in combination.

  When a conductive auxiliary is contained in the slurry, a dispersant is preferably contained together with the conductive auxiliary. Specific examples of the dispersant include polyvinyl pyrrolidone, polyvinyl alcohol, polyvinyl butyral, and a triazine compound. Of these dispersants, one type may be used alone, or two or more types may be used in combination.

  Next, the above slurry is applied to a current collector to form a negative electrode active material layer made of the slurry on the surface of the current collector. Thereafter, the solvent (the solvent of the slurry and the solvent contained in the intermediate composition) contained in the negative electrode active material layer is removed, and the negative electrode active material layer is dried and heat-treated. To cure. By this heat treatment, (A) the polyacrylic acid, (B) the polyfunctional amine, and (C) the polyfunctional carboxylic acid contained in the intermediate composition are condensed to form a negative active material layer of the present embodiment in the negative electrode active material layer. A polymer compound is formed. Note that the above heat treatment can be performed in a state where the solvent is contained in the negative electrode active material layer. However, it is more preferable that the heat treatment be performed in a state where the drying treatment is performed first and the negative electrode active material layer is dried.

  As a specific method of the drying treatment and the heat treatment, for example, a method of heating under a normal pressure or a reduced pressure by using a heat source such as hot air, infrared rays, microwaves, and high-frequency waves is used. When performing the heat treatment, it is preferable to heat from the current collector side rather than from the negative electrode active material layer side. In the drying treatment, it is preferable to heat slowly at a low temperature rather than quickly at a high temperature. In the heating treatment, it is preferable to heat quickly at a high temperature rather than slowly at a low temperature. By heating in this manner, characteristics (initial efficiency and cycle characteristics) of the power storage device can be improved.

  As the current collector, a known metal material used as a current collector for a negative electrode of a power storage device such as a secondary battery can be used. Examples of the metal material that can be used as the current collector include silver, copper, gold, aluminum, magnesium, tungsten, cobalt, zinc, nickel, iron, platinum, tin, indium, titanium, ruthenium, tantalum, molybdenum, and stainless steel. Can be

  The negative electrode using the polymer compound of the present embodiment as a negative electrode binder can be suitably used for a non-aqueous power storage device including a non-aqueous electrolyte as an electrolyte. Examples of the power storage device include a secondary battery, an electric double layer capacitor, and a lithium ion capacitor. Further, such a power storage device is useful as a non-aqueous secondary battery for driving motors of electric vehicles and hybrid vehicles, and a non-aqueous secondary battery used in personal computers, portable communication devices, home appliances, office equipment, industrial equipment, and the like. It is.

Next, effects of the present embodiment will be described.
(1) The polymer compound of the present embodiment is a polymer compound obtained by condensing (A) polyacrylic acid, (B) a polyfunctional amine, and (C) a polyfunctional carboxylic acid. Further, the polymer compound of the present embodiment has a chain structure composed of polyacrylic acid and a cross-linked structure that connects carboxylic acid side chains within the chain structure or between the chain structures, and has a cross-linked structure. Is at least one kind of crosslinked structure selected from the general formulas (2) to (4).

By using the polymer compound of the present embodiment as a negative electrode binder, the adhesiveness of the negative electrode active material layer is improved.
The chain structure composed of polyacrylic acid has a property of easily contracting when heat is applied. In the polymer compound used as the binder for the negative electrode, when the chain structure made of polyacrylic acid is in a heat-shrinked state, the ability of the chain structure to relieve a locally applied stress load is weakened. Would. For example, a chain structure made of polyacrylic acid may be thermally contracted by heat applied during heat treatment for curing the negative electrode active material layer or reaction heat generated during condensation (at the time of formation of an amide bond).

  The polymer compound of the present embodiment comprises (B) a plurality of benzene ring structures derived from a polyfunctional amine and (C) a carbon skeleton derived from a polyfunctional carboxylic acid between chain structures formed of polyacrylic acid. The presence of the annular structure makes it difficult for the chain structures to approach each other. Therefore, even when the chain structure is exposed to a high temperature, for example, during heat treatment, the heat shrinkage of the chain structure is suppressed, and the ability to relax the stress of the chain structure can be suitably maintained. Therefore, the polymer compound of the present embodiment is excellent in the ability to relieve stress, and can be used as a binder for a negative electrode to improve the adhesion of the negative electrode active material layer. In addition, the cycle characteristics of the power storage device are also improved by improving the adhesion of the negative electrode active material layer.

(2) In the partial structure of the crosslinked structure represented by the general formula (5), Y is a linear alkyl group having 1 to 4 carbon atoms, a phenylene group, or an oxygen atom.
According to the above configuration, by having a movable partial structure in the crosslinked structure, the elasticity of the polymer compound is improved. Thereby, the binder for a negative electrode using the polymer compound of the present embodiment easily follows a volume change due to expansion and contraction caused by occlusion and release of lithium and the like. As a result, the battery characteristics of the power storage device are improved.

(3) In the partial structure of the crosslinked structure represented by the general formula (5), Z is a fused polycyclic cyclic structure in which some atoms constituting the cyclic structure are shared among a plurality of cyclic structures. It is.
According to the above configuration, when the polymer compound is used as a negative electrode binder, the adhesiveness of the negative electrode active material layer is further improved.

  (4) In the partial structure of the crosslinked structure represented by the general formula (5), a linked polycyclic ring structure in which two or more ring structures are linked. The ratio of the structural part derived from the polyfunctional carboxylic acid (C) to the structural part derived from the polyfunctional amine (B) is 0.15 or more.

According to the above configuration, when the polymer compound is used as a binder for a negative electrode, the cycle characteristics of the power storage device are further improved.
(5) The polymer compound of the present embodiment has a site where a carboxyl group of polyacrylic acid and an amino group of a polyfunctional amine are bonded by an amide bond and a site where the carboxyl group is bonded by an imide bond. Further, the polymer compound of the present embodiment has, as a crosslinked structure, at least a crosslinked structure of the above general formula (2) and the above general formula (4), or at least a crosslinked structure of the above general formula (3).

  According to the above configuration, in a state where the negative electrode is formed by being mixed with the negative electrode active material, the strength of the electrode structure is increased. Accordingly, the electrode structure is easily maintained against a volume change due to expansion and contraction caused by occlusion and release of lithium and the like. As a result, the effect of improving the characteristics of the power storage device can be obtained more reliably.

  Further, according to the above configuration, the solubility of the polymer compound in organic substances such as a non-aqueous electrolyte is reduced. Therefore, it is considered that the effect of suppressing the elution of the polymer compound into the nonaqueous electrolyte during the electrochemical reaction can also be obtained.

Hereinafter, an example that further embodies the above embodiment will be described.
<Test 1>
Peeling of the negative electrode active material layer when a polymer compound obtained by condensing polyacrylic acid, a polyfunctional amine having a specific molecular structure, and a polyfunctional carboxylic acid having a cyclic molecular structure is used as a negative electrode binder The strength and the cycle characteristics of the power storage device were evaluated.

  Also, as a comparison, a polymer compound not condensing a polyfunctional carboxylic acid having a cyclic molecular structure, a polyfunctional carboxylic acid having an acyclic molecular structure instead of a polyfunctional carboxylic acid having a cyclic molecular structure, The peel strength of the negative electrode active material layer when the condensed polymer compound and the polycarboxylic acid were used as the negative electrode binder, and the cycle characteristics of the power storage device were also evaluated.

In the following, polyacrylic acid is described as “PAA” and N-methyl-2-pyrrolidone is described as “NMP”.
(Example 1: PAA + 4,4'-diaminodiphenylmethane + trimellitic acid)
PAA having a weight average molecular weight of 800,000 was dissolved in NMP to prepare a 10% by mass PAA / NMP solution, and 60 g of this PAA / NMP solution (83.3 mmol in terms of PAA monomer) was placed in a flask under a nitrogen atmosphere. I took it out. After 600 mg (2.85 mmol) of trimellitic acid was added to the flask and stirred at room temperature for 30 minutes, 8.2 g (20.1 mmol) of a 50% by mass NMP solution of 4,4′-diaminodiphenylmethane was further added dropwise. And stirred at room temperature for 30 minutes. Then, the intermediate composition of Example 1 was obtained in the state of an NMP solution by performing a heat treatment (preliminary heat treatment) at 110 ° C. for 3 hours using a Dean-Stark apparatus.

(Reference Example 1: PAA + 4,4'-diaminodiphenylmethane)
PAA having a weight average molecular weight of 800,000 was dissolved in NMP to prepare a 10% by mass PAA / NMP solution, and 62.1 g of this PAA / NMP solution (86.2 mmol in terms of PAA monomer) was added to a flask under a nitrogen atmosphere. Was taken in. 8.2 g (20.1 mmol) of a 50% by mass solution of 4,4′-diaminodiphenylmethane in NMP was dropped into the flask, and the mixture was stirred at room temperature for 30 minutes. Thereafter, the intermediate composition of Reference Example 1 was obtained in the form of an NMP solution by performing a heat treatment (preliminary heat treatment) at 110 ° C. for 3 hours using a Dean-Stark apparatus.

(Reference Example 2: PAA + 4,4′-diaminodiphenylmethane + 1,3,5-propanetricarboxylic acid)
PAA having a weight average molecular weight of 800,000 was dissolved in NMP to prepare a 10% by mass PAA / NMP solution, and 60 g of this PAA / NMP solution (83.3 mmol in terms of PAA monomer) was placed in a flask under a nitrogen atmosphere. I took it out. After 502 g (2.85 mmol) of 1,3,5-propanetricarboxylic acid was added to the flask and the mixture was stirred at room temperature for 30 minutes, 8.2 g of a 50% by mass solution of 4,4′-diaminodiphenylmethane in NMP (20. 1 mmol) was added dropwise and stirred at room temperature for 30 minutes. Thereafter, the mixture was subjected to heat treatment (preliminary heat treatment) at 110 ° C. for 3 hours using a Dean-Stark apparatus to obtain an intermediate composition of Reference Example 2 in the form of an NMP solution.

(Production of silicon material)
5 g of CaSi ₂ was added to 20 ml of concentrated hydrochloric acid containing 1% by mass of hydrogen fluoride which had been ice-bathed at 0 ° C., and the mixture was stirred for 1 hour. Then, water was added and the mixture was further stirred for 5 minutes. The yellow powder obtained by filtering the reaction solution was washed with water and ethanol, and dried under reduced pressure to obtain a layered polysilane. The obtained layered polysilane was heated to 500 ° C. in an argon atmosphere to obtain a silicon material in which hydrogen was released from the polysilane.

(Preparation of electrode sheet)
70 parts by mass of the silicon material, 15 parts by mass of natural graphite, 5 parts by mass of acetylene black, and 10 parts by mass of the NMP solution of the intermediate composition of Example 1 were mixed, and NMP was added to the mixture to prepare a slurry. The slurry was applied to the surface of a 30 μm electrolytic copper foil as a current collector in a film form using a doctor blade method. Then, the negative electrode active material layer was formed on the electrolytic copper foil by volatilizing and removing NMP in the slurry. Next, by using a roll press, by compressing the electrolytic copper foil and the negative electrode active material layer so that the thickness of the negative electrode active material layer becomes 20 μm, the electrolytic copper foil and the negative electrode active material layer are firmly adhered and joined. Was.

  Thereafter, the negative electrode active material layer in a state where the NMP is removed and dried is subjected to a heat treatment at 180 ° C. for 2 hours in a vacuum (under reduced pressure), so that the intermediate composition contained in the negative electrode active material layer is obtained. Was subjected to a condensation reaction, and the negative electrode active material layer was cured by heating. Thus, an electrode sheet containing a polymer compound having a crosslinked structure as a binder for a negative electrode was obtained.

Further, instead of the NMP solution of the example, a similar electrode sheet was produced using the intermediate compositions of PAA and Reference Examples 1 and 2.
(Evaluation of peel strength)
The obtained electrode sheet was cut into a size of 2.5 cm × 4 cm as a measurement sample, and a 90 ° peel test based on JIS K 6854-1 was performed using a peel test apparatus (manufactured by MINEBEA, LTS-50N-S300). Was done. The peel strength of the measurement sample was calculated by dividing the strength measured in the 90-degree peel test by the line width (2.5 cm). Table 1 shows the results. Note that the upper limit of the peel strength of the measurement sample that can be measured by the peel test apparatus used was 1.8 N / cm, and when it exceeded this value, it was set to “> 1.8”.

(Production of lithium ion secondary battery)
A separator is sandwiched between a negative electrode (evaluation electrode) obtained by cutting an electrode sheet into a circle having a diameter of 11 mm and a positive electrode obtained by cutting a metal lithium foil having a thickness of 500 μm into a circle having a diameter of 13 mm. It was a body battery. A lithium ion secondary battery was obtained by accommodating the electrode assembly battery and injecting a non-aqueous electrolyte into the battery case and sealing the battery case. As the separator, a glass filter manufactured by Hoechst Celanese Co., Ltd. and Celgard 2400 manufactured by Celgard Co., Ltd. were used. As the non-aqueous electrolyte, a non-aqueous electrolyte obtained by dissolving lithium hexafluorophosphate to a concentration of 1 M in a mixed solvent of ethylene carbonate and diethyl carbonate at a volume ratio of 1: 1 was used.

(Evaluation of battery characteristics)
The obtained lithium ion secondary battery was discharged at a direct current of 0.2 mA until the voltage of the negative electrode with respect to the positive electrode became 0.01 V, and 10 minutes after the discharge was completed, at a direct current of 0.2 mA. The battery was charged until the voltage of the negative electrode with respect to the positive electrode reached 1.0 V. The charge and discharge in a specified cycle were performed with the above discharge and charge as one cycle, and the cycle characteristics were calculated based on the following equation. Table 1 shows the results.

  Cycle characteristics (%) = (charge capacity after specified cycle / initial charge capacity) × 100

As shown in Table 1, in Test Example 1 using the polymer compound obtained from the intermediate composition of Example 1 as the binder for the negative electrode, as compared with Test Example 2 using PAA as the binder for the negative electrode, It was confirmed that the peel strength of the material layer was improved. From the results of Test Examples 3 and 4, the effect of improving the peel strength was confirmed in Test Example 3 in which a polymer compound not condensing a polyfunctional carboxylic acid having a cyclic molecular structure was used as a negative electrode binder, and It was confirmed that in Test Example 4 in which a polymer compound obtained by condensing a polyfunctional carboxylic acid having an acyclic molecular structure instead of the polyfunctional carboxylic acid having a cyclic molecular structure was used as a binder for a negative electrode, it was not obtained. did it.

  In addition, as compared with Test Example 2 in which PAA was used as a negative electrode binder, Test Examples 1, 3, and 4 in which a polymer compound in which a polyfunctional amine having a specific molecular structure was condensed were used as a negative electrode binder. It was confirmed that the cycle characteristics of the secondary battery were improved. Among these Test Examples 1, 3, and 4, a test using a polymer compound in which a polyfunctional amine having a specific molecular structure and a polyfunctional carboxylic acid having a cyclic molecular structure are condensed was used as a binder for a negative electrode. It was confirmed that Example 1 exhibited particularly high cycle characteristics.

<Test 2>
Next, when a polymer compound obtained by condensing PAA, a polyfunctional amine having a specific molecular structure, and a polyfunctional carboxylic acid having a cyclic molecular structure is used as a negative electrode binder, The change in the peel strength of the negative electrode active material layer when the conditions of the preliminary heat treatment during preparation were varied was evaluated.

(Example 1A: PAA + 4,4′-diaminodiphenylmethane + trimellitic acid)
PAA having a weight average molecular weight of 800,000 was dissolved in NMP to prepare a 10% by mass PAA / NMP solution, and 60 g of this PAA / NMP solution (83.3 mmol in terms of PAA monomer) was placed in a flask under a nitrogen atmosphere. I took it out. After 600 mg (2.85 mmol) of trimellitic acid was added to the flask and stirred at room temperature for 30 minutes, 8.2 g (20.1 mmol) of a 50% by mass NMP solution of 4,4′-diaminodiphenylmethane was further added dropwise. And stirred at room temperature for 30 minutes. Thereafter, the mixture was subjected to heat treatment (preliminary heat treatment) at 130 ° C. for 3 hours using a Dean-Stark apparatus to obtain an intermediate composition of Example 1A in the form of an NMP solution.

(Evaluation of peel strength)
Using the intermediate composition of Example 1A, an electrode sheet was prepared using a polymer compound obtained from the intermediate composition as a negative electrode binder, and the peel strength of the negative electrode active material layer in the obtained electrode sheet was evaluated. Table 2 shows the results. The method for producing the electrode sheet and the method for evaluating the peel strength are the same as those in Test 1.

As shown in Table 2, it was confirmed that the peel strength of the negative electrode active material layer was further improved by increasing the temperature of the preheating treatment performed during the preparation of the intermediate composition.

<Test 3>
Next, when a polymer compound obtained by condensing PAA, a polyfunctional amine having a specific molecular structure, and a polyfunctional carboxylic acid having a cyclic molecular structure is used as a negative electrode binder, the molecular weight of PAA is reduced. The change in the peel strength of the negative electrode active material layer in the case where the difference was made was evaluated.

(Example 2: PAA + 4,4′-diaminodiphenylmethane + trimellitic acid)
Water was removed from a PAA aqueous solution having a weight average molecular weight of 100,000 by vacuum drying and solvent replacement with acetone until the water content became 1% by mass or less. PAA from which water was removed was dissolved in NMP to prepare a 10% by mass PAA / NMP solution, and 60 g of this PAA / NMP solution (83.3 mmol in terms of PAA monomer) was dispensed into a flask under a nitrogen atmosphere. did. After 600 mg (2.85 mmol) of trimellitic acid was added to the flask and stirred at room temperature for 30 minutes, 8.2 g (20.1 mmol) of a 50% by mass NMP solution of 4,4′-diaminodiphenylmethane was further added dropwise. And stirred at room temperature for 30 minutes. Thereafter, the mixture was subjected to a heat treatment (preliminary heat treatment) at 130 ° C. for 3 hours using a Dean-Stark apparatus to obtain the intermediate composition of Example 2 in the form of an NMP solution.

(Evaluation of peel strength)
Using the intermediate composition of Example 2, an electrode sheet was prepared using a polymer compound obtained from the intermediate composition as a negative electrode binder, and the peel strength of the negative electrode active material layer in the obtained electrode sheet was evaluated. Table 3 shows the results. The method for producing the electrode sheet and the method for evaluating the peel strength are the same as those in Test 1.

As shown in Table 3, even when the molecular weight of PAA was changed, no large difference was confirmed in the peel strength of the negative electrode active material layer. From this result, in a polymer compound obtained by condensing PAA, a polyfunctional amine having a specific molecular structure, and a polyfunctional carboxylic acid having a cyclic molecular structure, the length of the chain structure portion composed of PAA is: However, it is suggested that it does not significantly affect the molecular structure of the polymer compound.

<Test 4>
Next, when a polymer compound obtained by condensing PAA, a polyfunctional amine having a specific molecular structure, and a polyfunctional carboxylic acid having a cyclic molecular structure is used as a negative electrode binder, the specific molecular structure The change in the peel strength of the negative electrode active material layer and the change in the cycle characteristics of the power storage device were evaluated when different types of polyfunctional amines having the same were used.

(Example 3: PAA + 4,4′-diaminodiphenyl ether + trimellitic acid)
PAA having a weight average molecular weight of 800,000 was dissolved in NMP to prepare a 10% by mass PAA / NMP solution, and 60 g of this PAA / NMP solution (83.3 mmol in terms of PAA monomer) was placed in a flask under a nitrogen atmosphere. I took it out. After adding 600 mg (2.85 mmol) of trimellitic acid to the flask and stirring at room temperature for 30 minutes, 8.1 g (20.1 mmol) of a 50% by mass NMP solution of 4,4′-diaminodiphenyl ether was further added dropwise. And stirred at room temperature for 30 minutes. Thereafter, the mixture was subjected to a heat treatment (preliminary heat treatment) at 130 ° C. for 3 hours using a Dean-Stark apparatus, whereby an intermediate composition of Example 3 was obtained in the form of an NMP solution.

(Example 4: PAA + 4,4′-diaminobenzophenone + trimellitic acid)
PAA having a weight average molecular weight of 800,000 was dissolved in NMP to prepare a 10% by mass PAA / NMP solution, and 60 g of this PAA / NMP solution (83.3 mmol in terms of PAA monomer) was placed in a flask under a nitrogen atmosphere. I took it out. After 600 mg (2.85 mmol) of trimellitic acid was added to the flask and stirred at room temperature for 30 minutes, 8.5 g (20.1 mmol) of a 50% by mass solution of 4,4′-diaminobenzophenone in NMP was further added dropwise. And stirred at room temperature for 30 minutes. Thereafter, the mixture was subjected to a heat treatment (preliminary heat treatment) at 130 ° C. for 3 hours using a Dean-Stark apparatus to obtain an intermediate composition of Example 4 in the form of an NMP solution.

(Evaluation of peel strength and evaluation of battery characteristics)
Using the intermediate compositions of Examples 1A, 3, and 4, an electrode sheet was prepared using a polymer compound obtained from the intermediate composition as a negative electrode binder, and the peel strength of the negative electrode active material layer in the obtained electrode sheets was evaluated. did. In addition, a lithium ion secondary battery was manufactured using the obtained electrode sheet, and the cycle characteristics of the lithium ion secondary battery were evaluated. Table 4 shows the results. Note that the method for preparing the electrode sheet, the method for preparing the lithium ion secondary battery, the method for evaluating the peel strength, and the method for evaluating the cycle characteristics of the lithium ion secondary battery are the same as those in Test 1.

As shown in Table 4, even when the kind of the polyfunctional amine having a specific molecular structure was changed, no large difference was confirmed in the peel strength of the negative electrode active material layer and the cycle characteristics of the secondary battery. From these results, in the polymer compound obtained by condensing PAA, a polyfunctional amine having a specific molecular structure, and a polyfunctional carboxylic acid having a cyclic molecular structure, the structure of the polyfunctional amine is a polymer compound It does not have a significant effect on the molecular structure of.

<Test 5>
Next, when a polymer compound obtained by condensing PAA, a polyfunctional amine having a specific molecular structure, and a polyfunctional carboxylic acid having a cyclic molecular structure is used as a binder for a negative electrode, the cyclic molecular structure is reduced. The change in the peel strength of the negative electrode active material layer and the change in the cycle characteristics of the power storage device when the types of the polyfunctional carboxylic acids having different types of carboxylic acids were different were evaluated.

(Example 5: PAA + 4,4′-diaminodiphenylmethane + 1,2,4-cyclohexanetricarboxylic acid)
PAA having a weight average molecular weight of 800,000 was dissolved in NMP to prepare a 10% by mass PAA / NMP solution, and 60 g of this PAA / NMP solution (83.3 mmol in terms of PAA monomer) was placed in a flask under a nitrogen atmosphere. I took it out. After 616.1 mg (2.85 mmol) of 1,2,4-cyclohexanetricarboxylic acid was added to the flask and stirred at room temperature for 30 minutes, a 50% by mass NMP solution of 4,4′-diaminodiphenylmethane was added. 2 g (20.1 mmol) was added dropwise, and the mixture was stirred at room temperature for 30 minutes. Thereafter, the intermediate composition of Example 5 was obtained in the state of an NMP solution by performing a heat treatment (preliminary heat treatment) at 110 ° C. for 3 hours using a Dean-Stark apparatus.

(Example 6: PAA + 4,4′-diaminodiphenylmethane + 2,3,4,5-tetrahydrofurantetracarboxylic acid)
PAA having a weight average molecular weight of 800,000 was dissolved in NMP to prepare a 10% by mass PAA / NMP solution, and 60 g of this PAA / NMP solution (83.3 mmol in terms of PAA monomer) was placed in a flask under a nitrogen atmosphere. I took it out. 707.2 mg (2.85 mmol) of 2,3,4,5-tetrahydrofurantetracarboxylic acid was added to the flask, and the mixture was stirred at room temperature for 30 minutes. Then, a 50% by mass NMP solution of 4,4′-diaminodiphenylmethane 8 was added. .2 g (20.1 mmol) was added dropwise and stirred at room temperature for 30 minutes. Thereafter, the mixture was subjected to a heat treatment (preliminary heat treatment) at 110 ° C. for 3 hours using a Dean-Stark apparatus to obtain an intermediate composition of Example 6 in a state of an NMP solution.

(Example 7: PAA + 4,4'-diaminodiphenylmethane + 1,4-cyclohexanedicarboxylic acid)
PAA having a weight average molecular weight of 800,000 was dissolved in NMP to prepare a 10% by mass PAA / NMP solution, and 60 g of this PAA / NMP solution (83.3 mmol in terms of PAA monomer) was placed in a flask under a nitrogen atmosphere. I took it out. 490.7 mg (2.85 mmol) of 1,4-cyclohexanedicarboxylic acid was added to the flask, stirred at room temperature for 30 minutes, and then 8.2 g of a 50% by mass solution of 4,4′-diaminodiphenylmethane in NMP ( 20.1 mmol) was added dropwise and stirred at room temperature for 30 minutes. Thereafter, the mixture was subjected to a heat treatment (preliminary heat treatment) at 110 ° C. for 3 hours using a Dean-Stark apparatus, whereby an intermediate composition of Example 7 was obtained in the form of an NMP solution.

(Example 8: PAA + 4,4'-diaminodiphenylmethane + bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride)
PAA having a weight average molecular weight of 800,000 was dissolved in NMP to prepare a 10% by mass PAA / NMP solution, and 60 g of this PAA / NMP solution (83.3 mmol in terms of PAA monomer) was placed in a flask under a nitrogen atmosphere. I took it out. After adding 707.3 mg (2.85 mmol) of bicyclo [2.2.2] oct-7-ene-2,3,5,6-tetracarboxylic dianhydride in the flask and stirring at room temperature for 30 minutes, Further, 8.2 g (20.1 mmol) of a 50% by mass NMP solution of 4,4′-diaminodiphenylmethane was added dropwise, and the mixture was stirred at room temperature for 30 minutes. Thereafter, the mixture was subjected to heat treatment (preliminary heat treatment) at 110 ° C. for 3 hours using a Dean-Stark apparatus to obtain an intermediate composition of Example 8 in the form of an NMP solution.

(Example 9: PAA + 4,4′-diaminodiphenylmethane + 3,4,9,10-perylenetetracarboxylic dianhydride)
PAA having a weight average molecular weight of 800,000 was dissolved in NMP to prepare a 10% by mass PAA / NMP solution, and 60 g of this PAA / NMP solution (83.3 mmol in terms of PAA monomer) was placed in a flask under a nitrogen atmosphere. I took it out. 1.118 mg (2.85 mmol) of 3,4,9,10-perylenetetracarboxylic dianhydride was added to the flask, and the mixture was stirred at room temperature for 30 minutes. Then, 50% by mass of 4,4′-diaminodiphenylmethane was further added. 8.2 g (20.1 mmol) of NMP solution was added dropwise, and the mixture was stirred at room temperature for 30 minutes. Thereafter, the intermediate composition of Example 9 was obtained in the state of an NMP solution by performing a heat treatment (preliminary heat treatment) at 110 ° C. for 3 hours using a Dean-Stark apparatus.

(Evaluation of peel strength and evaluation of battery characteristics)
Using the intermediate compositions of Examples 5 to 9, electrode sheets were prepared using the polymer compound obtained from the intermediate compositions as a negative electrode binder, and the peel strength of the negative electrode active material layer in the obtained electrode sheets was evaluated. In addition, a lithium ion secondary battery was manufactured using the obtained electrode sheet, and the cycle characteristics of the lithium ion secondary battery were evaluated. Table 5 shows the results. Note that the method for preparing the electrode sheet, the method for preparing the lithium ion secondary battery, the method for evaluating the peel strength, and the method for evaluating the cycle characteristics of the lithium ion secondary battery are the same as those in Test 1.

As shown in Table 5, even when the kind of the polyfunctional carboxylic acid having a cyclic molecular structure was changed, the peeling of the negative electrode active material layer was equal to or more than that of Test Example 1 using trimellitic acid. It was confirmed that strength and cycle characteristics of the secondary battery were obtained.

  In particular, in Test Example 14 using a polyfunctional carboxylic acid having a fused polycyclic molecular structure, higher peel strength was obtained. This result suggests that the fused polycyclic molecular structure has a particularly high property of restricting the approach between the chain structures composed of PAA and suppressing the heat shrinkage of the chain structure.

<Test 6>
Next, when a polymer compound obtained by condensing PAA, a polyfunctional amine having a specific molecular structure, and a polyfunctional carboxylic acid having a cyclic molecular structure is used as a negative electrode binder, the other negative electrode binder is used. The change in peel strength of the negative electrode active material layer and the change in cycle characteristics of the power storage device when a binder was used in combination were evaluated. As the other binder for the negative electrode, a polymer compound obtained by condensing PAA and a polyfunctional amine having a specific molecular structure (a polymer compound obtained from the intermediate composition of Reference Example 1) was used.

(Preparation of electrode sheet)
70 parts by mass of the above silicon material, 15 parts by mass of natural graphite, 5 parts by mass of acetylene black, and 10 parts by mass of an NMP solution of the intermediate composition were mixed, and NMP was added to this mixture to prepare a slurry. The slurry was applied to the surface of a 30 μm electrolytic copper foil as a current collector in a film form using a doctor blade method. Then, the negative electrode active material layer was formed on the electrolytic copper foil by volatilizing and removing NMP in the slurry. Next, by using a roll press, by compressing the electrolytic copper foil and the negative electrode active material layer so that the thickness of the negative electrode active material layer becomes 20 μm, the electrolytic copper foil and the negative electrode active material layer are firmly adhered and joined. Was.

  Thereafter, the negative electrode active material layer in a state where the NMP is removed and dried is subjected to a heat treatment at 180 ° C. for 2 hours in a vacuum (under reduced pressure), so that the intermediate composition contained in the negative electrode active material layer is obtained. Was subjected to a condensation reaction, and the negative electrode active material layer was cured by heating. Thus, an electrode sheet containing a polymer compound having a crosslinked structure as a binder for a negative electrode was obtained.

  In this test, the NMP solution of the intermediate composition of Example 1A and the intermediate composition of Reference Example 1 were used together in the ratio (mass ratio) shown in Table 6 as the NMP solution of the intermediate composition. In Table 6, the first polymer compound is a polymer compound obtained by condensing PAA, a polyfunctional amine having a specific molecular structure, and a polyfunctional carboxylic acid having a cyclic molecular structure. The molecular compound is a polymer compound obtained by condensing PAA with a polyfunctional amine having a specific molecular structure.

(Evaluation of peel strength and evaluation of battery characteristics)
The peel strength of the negative electrode active material layer in the obtained electrode sheet was evaluated. In addition, a lithium ion secondary battery was manufactured using the obtained electrode sheet, and the cycle characteristics of the lithium ion secondary battery were evaluated. Table 6 shows the results. The method for manufacturing the lithium ion secondary battery, the method for evaluating the peel strength, and the method for evaluating the cycle characteristics of the lithium ion secondary battery are the same as those in Test 1.

As shown in Table 6, even when a polymer compound (second polymer compound) obtained by condensing PAA and a polyfunctional amine having a specific molecular structure is used in combination as a binder for a negative electrode, high peel strength is obtained. It was confirmed that it was obtained.

<Test 7>
Next, when a polymer compound obtained by condensing PAA, a polyfunctional amine having a specific molecular structure, and a polyfunctional carboxylic acid having a cyclic molecular structure was used as a negative electrode binder, Test 5 The change in the peel strength of the negative electrode active material layer and the change in the cycle characteristics of the power storage device when using a polyfunctional carboxylic acid having another cyclic molecular structure were evaluated.

(Example 10: PAA + 4,4′-diaminodiphenylmethane + pyromellitic anhydride)
PAA having a weight-average molecular weight of 250,000 was dissolved in NMP to prepare a 15% by mass PAA / NMP solution, and 12.7 g (26.5 mmol in terms of PAA monomer) of this PAA / NMP solution was placed in a flask under a nitrogen atmosphere. Was taken in. 2.58 g (6.5 mmol) of a 50% by mass solution of 4,4′-diaminodiphenylmethane in NMP was added to the flask, stirred at room temperature for 30 minutes, and then at 100 ° C. for 1 hour. Thereafter, the reaction mixture in the flask was cooled to room temperature. Then, 1.93 g (0.91 mmol) of a 10% by mass pyromellitic anhydride NMP solution in pyromellitic anhydride was added to the flask, and the mixture was heated at 80 ° C. for 30 minutes (preliminary heat treatment), whereby Example 10 was obtained. The intermediate composition was obtained in the form of an NMP solution.

(Example 11: PAA + 4,4′-diaminodiphenylmethane + 3,3 ′, 4,4′-benzophenonetetracarboxylic anhydride)
PAA having a weight-average molecular weight of 250,000 was dissolved in NMP to prepare a 15% by mass PAA / NMP solution, and 12.7 g (26.5 mmol in terms of PAA monomer) of this PAA / NMP solution was placed in a flask under a nitrogen atmosphere. Was taken in. 2.58 g (6.5 mmol) of a 50% by mass solution of 4,4′-diaminodiphenylmethane in NMP was added to the flask, stirred at room temperature for 30 minutes, and then at 100 ° C. for 1 hour. Thereafter, the reaction mixture in the flask was cooled to room temperature. Then, 3.0 g (0.91 mmol) of a 10% by mass NMP solution of 3,3 ′, 4,4′-benzophenonetetracarboxylic anhydride is added to the flask, and heat treatment is performed at 80 ° C. for 30 minutes (preliminary). By heat treatment, the intermediate composition of Example 11 was obtained in the state of an NMP solution.

(Evaluation of peel strength and evaluation of battery characteristics)
Using the intermediate compositions of Examples 10 and 11, electrode sheets were prepared using a polymer compound obtained from the intermediate compositions as a negative electrode binder, and the peel strength of the negative electrode active material layer in the obtained electrode sheets was evaluated. In addition, a lithium ion secondary battery was manufactured using the electrode sheet, and the cycle characteristics of the lithium ion secondary battery were evaluated. Further, an electrode sheet and a lithium ion secondary battery were prepared using PAA instead of the NMP solution of the example, and the peel strength of the negative electrode active material layer and the cycle characteristics of the lithium ion secondary battery were evaluated. Table 7 shows the results. Note that the method for preparing the electrode sheet, the method for preparing the lithium ion secondary battery, the method for evaluating the peel strength, and the method for evaluating the cycle characteristics of the lithium ion secondary battery are the same as those in Test 1.

As shown in Table 6, in Test Examples 17 and 18 using the polymer compound obtained from the intermediate composition of Examples 10 and 11 as the binder for the negative electrode, comparison was also made with Test Example 19 using PAA as the binder for the negative electrode. As a result, it was confirmed that the peel strength of the negative electrode active material layer and the cycle characteristics of the secondary battery were improved.

<Test 8>
Next, when a polymer compound obtained by condensing PAA, a polyfunctional amine having a specific molecular structure, and a polyfunctional carboxylic acid having a cyclic molecular structure is used as a negative electrode binder, The change in the peel strength of the negative electrode active material layer and the change in the initial efficiency and cycle characteristics of the power storage device when the mixing ratio of the polyfunctional carboxylic acid having a cyclic molecular structure was changed were evaluated.

(Examples 11-1 to 11-8: PAA + 4,4′-diaminodiphenylmethane + 3,3 ′, 4,4′-benzophenonetetracarboxylic anhydride)
With respect to the intermediate composition of Example 11, the blending amounts of 4,4′-diaminodiphenylmethane and 3,3 ′, 4,4′-benzophenonetetracarboxylic anhydride were changed to adjust the amount of the polyfunctional carboxylic acid to the polyfunctional amine. Intermediate compositions of Examples 11-1 to 11-8 having different mixing ratios were prepared. The blending amounts of the polyfunctional amine and polyfunctional carboxylic acid in each example are as shown in Tables 8 and 9. In addition, about Example 11-2, it is the same intermediate composition as the said Example 11. For Examples 11-1, 11-3 to 10-8, except that the blending amounts of 4,4′-diaminodiphenylmethane and 3,3 ′, 4,4′-benzophenonetetracarboxylic anhydride were different. Prepared in the same manner as in Example 11.

(Examples 10-1 to 10-2: PAA + 4,4′-diaminodiphenylmethane + pyromellitic anhydride)
With respect to the intermediate composition of Example 10, the amounts of 4,4'-diaminodiphenylmethane and pyromellitic anhydride were varied, and the blending ratio of polyfunctional carboxylic acid to polyfunctional amine was changed from Examples 10-1 to 10 to 10. -2 intermediate composition was prepared. The blending amounts of the polyfunctional amine and the polyfunctional carboxylic acid in each example are as shown in Table 9. In addition, about Example 10-1, it is the same intermediate composition as the said Example 10. Example 10-2 was prepared in the same manner as in Example 10, except that the amounts of 4,4'-diaminodiphenylmethane and pyromellitic anhydride were different.

(Examples 12-1 to 12-2: PAA + 4,4′-diaminodiphenylmethane + trimellitic anhydride)
PAA having a weight-average molecular weight of 250,000 was dissolved in NMP to prepare a 15% by mass PAA / NMP solution, and 12.7 g (26.5 mmol in terms of PAA monomer) of this PAA / NMP solution was placed in a flask under a nitrogen atmosphere. Was taken in. A predetermined amount of a 50% by mass NMP solution of 4,4′-diaminodiphenylmethane was added to the flask, stirred at room temperature for 30 minutes, and then at 100 ° C. for 1 hour. Thereafter, the reaction mixture in the flask was cooled to room temperature. Then, a predetermined amount of a 10% by mass NMP solution of trimellitic anhydride was added to the flask, and heat treatment (preheating treatment) was performed at 80 ° C. for 30 minutes, whereby Examples 12-1 to 12-2 were obtained. Was obtained in the form of an NMP solution. The blending amounts of the polyfunctional amine and the polyfunctional carboxylic acid in each example are as shown in Table 9.

(Evaluation of peel strength and evaluation of battery characteristics)
Using the intermediate composition of each example, an electrode sheet was prepared using a polymer compound obtained from the intermediate composition as a negative electrode binder, and the peel strength of the negative electrode active material layer in the obtained electrode sheet was evaluated. The results are shown in Tables 8 and 9. The method for preparing the electrode sheet, the method for preparing the lithium ion secondary battery, and the method for evaluating the peel strength are the same as those in Test 1.

Further, a lithium ion secondary battery was manufactured using the obtained electrode sheet, and the initial efficiency and cycle characteristics of the lithium ion secondary battery were evaluated.
The obtained lithium ion battery was discharged at a direct current of 0.2 mA until the voltage of the negative electrode with respect to the positive electrode became 0.01 V. Ten minutes after the discharge was completed, the negative electrode was discharged at a direct current of 0.2 mA. The battery was charged until the voltage with respect to the positive electrode became 1.0 V. The discharge capacity at this time was set as the initial discharge capacity, and the charge capacity was set as the initial charge capacity. Then, the initial efficiency was calculated based on the following equation. The results are shown in Tables 8 and 9.

Initial efficiency (%) = (initial charge capacity / initial discharge capacity) × 100
Further, the above-described discharge and charge were defined as one cycle, and charge and discharge were performed in a specified cycle, and cycle characteristics were calculated based on the following equation. The results are shown in Tables 8 and 9.

  Cycle characteristics (%) = (charge capacity after specified cycle / initial charge capacity) × 100

As shown in Tables 8 and 9, it was confirmed that the cycle characteristics tended to improve as the blending ratio of the polyfunctional carboxylic acid having a cyclic molecular structure to the polyfunctional amine was increased.

  In Example 10-2 (Test Example 29), pyromellitic anhydride was used as the polyfunctional carboxylic acid having a cyclic molecular structure, and the compounding ratio with respect to the polyfunctional amine was “0.22”. During the preparation of the composition, the polyfunctional carboxylic acid crystallized and phase-separated, so that it was not possible to obtain an intermediate composition having a desired blending ratio.

  On the other hand, when 3,3 ′, 4,4′-benzophenonetetracarboxylic anhydride is used as the polyfunctional carboxylic acid having a cyclic molecular structure, and when trimellitic anhydride is used, the polyfunctional carboxylic acid has a high molecular weight. Even when the blending ratio with respect to the functional amine was increased to “1.0”, the polyfunctional carboxylic acid did not crystallize and undergo phase separation during preparation of the intermediate composition.

  From these results, it is understood that it is preferable to increase the mixing ratio of the polyfunctional carboxylic acid having a cyclic molecular structure to the polyfunctional amine from the viewpoint of improving the cycle characteristics. And, as a polyfunctional carboxylic acid having a cyclic molecular structure, it is easier to increase the blending ratio when a compound that is difficult to phase separate due to crystallization during preparation of the intermediate composition is used, and the cycle characteristics are increased to higher values. It can be seen that it can be improved.

  In addition, 3,3 ′, 4,4′-benzophenonetetracarboxylic anhydride has a molecular structure in which two or more cyclic structures having a carboxyl group are connected, and at a connecting portion between the cyclic structures, Movement such as rotation in the molecule is allowed. Therefore, it is considered that the flexibility of the molecule is increased, crystallization hardly occurs during the preparation of the intermediate composition, and the blending ratio can be increased. It is considered that trimellitic anhydride has asymmetric molecular structure, so that crystallization hardly occurs during preparation of the intermediate composition, and the blending ratio can be increased.

Next, technical ideas that can be grasped from the above embodiments and examples will be additionally described below.
(A) A binder for a negative electrode containing the polymer compound.
(B) A method for manufacturing a negative electrode of a power storage device, comprising: a step of forming a negative electrode active material layer on a current collector using a mixture containing the intermediate composition and a negative electrode active material; A heat treatment of the negative electrode active material layer to condense the polyacrylic acid and the polyfunctional amine, and a condensation step of condensing the polyfunctional amine and the polyfunctional carboxylic acid. Method.

Claims (14)

The Po Riakuriru acid has a chain structure constituted, and a cross-linked structure that connects the carboxylic acid side chain with each other between the chain-like structure in or chain structure,
The polymer compound, wherein the crosslinked structure is at least one type of crosslinked structure selected from the following general formulas (2) to (4).
(PAA indicates a chain structure composed of polyacrylic acid, and X is a structure represented by the following general formula (5).)
(Y is a linear alkyl group having 1 to 4 carbon atoms, a phenylene group, or an oxygen atom, and R1 and R2 are each independently a single or plural hydrogen atoms, a methyl group, an ethyl group, a trifluoromethyl group. Or a methoxy group, Z is a cyclic structure having a carbon skeleton, A1 and A2 are each independently a hydrogen atom or a carbonyl carbon, and n is an integer of 1 to 5.) The polymer compound according to claim 1 , wherein Z in the crosslinked structure is a polycyclic ring structure in which a ring structure having two or more carbon skeletons is linked.   A binder for a negative electrode of a power storage device, comprising the polymer compound according to claim 1 or 2. An intermediate composition of a polymer compound used as a binder for a negative electrode according to claim 3 ,
A polyacrylic acid, a polyfunctional amine represented by the following general formula (1), a polyfunctional carboxylic acid having a cyclic molecular structure, containing a non-aqueous solvent, to name a liquid,
An intermediate composition, wherein a blending ratio of the polyfunctional carboxylic acid to the polyfunctional amine (polyfunctional carboxylic acid / polyfunctional amine) is 0.14 or less .
(Y is a linear alkyl group having 1 to 4 carbon atoms, a phenylene group, or an oxygen atom, and R1 and R2 are each independently a single or plural hydrogen atoms, a methyl group, an ethyl group, a trifluoromethyl group. Or a methoxy group.) An intermediate composition of a polymer compound used as a binder for a negative electrode according to claim 3 ,
A polyacrylic acid, a polyfunctional amine represented by the following general formula (1), a polyfunctional carboxylic acid having a cyclic molecular structure, containing a non-aqueous solvent, to name a liquid,
The polyfunctional carboxylic acid is at least one selected from a polyfunctional carboxylic acid having a cyclic structure composed of two or more carbon skeletons having a carboxyl group and a polyfunctional carboxylic acid having an asymmetric molecular structure. Intermediate composition to be used.
(Y is a linear alkyl group having 1 to 4 carbon atoms, a phenylene group, or an oxygen atom, and R1 and R2 are each independently a single or plural hydrogen atoms, a methyl group, an ethyl group, a trifluoromethyl group. Or a methoxy group.) The intermediate according to claim 4 or 5, wherein the polyfunctional carboxylic acid is a polycyclic polyfunctional carboxylic acid in which a cyclic structure comprising two or more carbon skeletons having a carboxyl group is connected. Composition. A method for producing a polymer compound according to claim 1 or claim 2 ,
A polymer compound characterized by heating polyacrylic acid, a polyfunctional amine represented by the following general formula (1), and a polyfunctional carboxylic acid having a cyclic molecular structure at a temperature of 150 ° C to 230 ° C. Production method.
(Y is a linear alkyl group having 1 to 4 carbon atoms, a phenylene group, or an oxygen atom, and R1 and R2 are each independently a single or plural hydrogen atoms, a methyl group, an ethyl group, a trifluoromethyl group. Or a methoxy group.)   After pre-heating the polyacrylic acid, the polyfunctional amine, the polyfunctional carboxylic acid, and the non-aqueous solvent-containing intermediate composition at a temperature of 40 ° C to 140 ° C, a temperature of 150 ° C to 230 ° C The method for producing a polymer compound according to claim 7, wherein the heating is performed at a temperature. A negative electrode of the power storage device,
A negative electrode binder according to claim 3, comprising a negative electrode active material,
A negative electrode comprising, as the negative electrode active material, at least one selected from a carbon-based material capable of inserting and extracting lithium, an element alloyable with lithium, and a compound having an element alloyable with lithium. electrode. The negative electrode active material contains at least one selected from a silicon material obtained from CaSi ₂ through a decalcification reaction, Si, and SiO _V (0 < v ≦ 2). Negative electrode.   A power storage device comprising the negative electrode according to claim 9 and a non-aqueous electrolyte. A slurry for a negative electrode used for manufacturing a negative electrode of a power storage device,
An intermediate composition according to any one of claims 4 to 6 , a negative electrode active material, and a solvent,
A negative electrode comprising, as the negative electrode active material, at least one selected from a carbon-based material capable of inserting and extracting lithium, an element alloyable with lithium, and a compound having an element alloyable with lithium. Slurry for electrodes. A method for manufacturing a negative electrode of a power storage device,
A method for manufacturing a negative electrode, comprising forming a negative electrode active material layer on a current collector using the slurry for a negative electrode according to claim 12. The slurry for a negative electrode includes, as the negative electrode active material, at least one selected from a silicon material obtained from CaSi ₂ through a decalcification reaction, Si, and SiO _V (0 < v ≦ 2). The method for producing a negative electrode according to claim 13.