WO2021187407A1

WO2021187407A1 - Composition for power storage device, slurry for power storage device electrode, power storage device electrode, and power storage device

Info

Publication number: WO2021187407A1
Application number: PCT/JP2021/010328
Authority: WO
Inventors: 香奈増田; 卓哉中山
Original assignee: Jsr株式会社
Priority date: 2020-03-19
Filing date: 2021-03-15
Publication date: 2021-09-23
Also published as: JPWO2021187407A1

Abstract

Provided is a composition for a power storage device which has excellent flexibility and adhesion and from which a power storage device electrode exhibiting good charge-and-discharge durability characteristics can be produced.　A composition for a power storage device according to the present invention contains a polymer (A) and a liquid medium (B), wherein when the total amount of repeating units contained in the polymer (A) is 100 parts by mass, the polymer (A) contains: 1-50 parts by mass of a repeating unit (a1) derived from a compound having a cyclic carbonate group; and 50-99 parts by mass of at least one repeating unit selected from the group consisting of a repeating unit (a2) derived from an unsaturated carboxylic acid, a repeating unit (a3) derived from a (meth)acrylamide, a repeating unit (a4) derived from a compound having a sulfo group, and a repeating unit (a5) derived from a compound having a hydroxyl group.

Description

Composition for power storage device, slurry for power storage device electrode, power storage device electrode, and power storage device

The present invention relates to a composition for a power storage device, a slurry for a power storage device electrode containing the composition, a power storage device electrode formed by applying and drying the slurry to a current collector, and a power storage device provided with the electrode. ..

In recent years, a power storage device having a high voltage and a high energy density has been required as a power source for driving an electronic device. Lithium-ion batteries, lithium-ion capacitors, and the like are expected as such power storage devices.

The electrodes used in such a power storage device are manufactured by applying a composition (slurry for electrodes) containing an active material and a polymer functioning as a binder to the surface of a current collector and drying it. The properties required for the polymer used as a binder include the ability to bond the active materials to each other, the ability to adhere the active material to the current collector, the abrasion resistance in the process of winding the electrodes, and the subsequent cutting. Examples include powder drop resistance in which fine powder of the active material does not fall off from the coated / dried composition coating film (hereinafter, also referred to as “active material layer”).

It has been empirically clarified from experience that the quality of the performance is almost proportional to the binding ability between the active materials, the adhesion ability between the active material and the current collector, and the resistance to powder dropping. Therefore, in the present specification, these may be comprehensively expressed by using the term “adhesion”.

In recent years, from the viewpoint of achieving higher output and higher energy density of power storage devices, studies on using a material having a large lithium occlusion as an active material have been promoted. For example, as disclosed in Patent Document 1, a method of utilizing a silicon material having a maximum theoretical occlusion of lithium of about 4,200 mAh / g as an active material is promising.

However, an active material using such a material having a large amount of lithium occlusion is accompanied by a large volume change due to the occlusion and release of lithium. For this reason, when a conventionally used electrode binder is applied to such a material having a large lithium occlusion, the active material cannot be maintained and the active material is peeled off, which is remarkable with charging and discharging. Capacity drop occurs.

As a technique for improving the adhesion of the binder for the electrode, a technique for controlling the surface acid amount of the particulate binder particles (see Patent Documents 2 and 3) and a binder having an epoxy group or a hydroxy group are used. Therefore, techniques for improving the above characteristics (see Patent Document 4 and Patent Document 5) and the like have been proposed. Further, a technique has been proposed in which the active material is bound by the rigid molecular structure of polyimide to suppress the volume change of the active material (see Patent Document 6).

Japanese Unexamined Patent Publication No. 2004-185810 International Publication No. 2011/096463 International Publication No. 2013/191080 Japanese Unexamined Patent Publication No. 2010-205722 Japanese Unexamined Patent Publication No. 2010-3703 Japanese Unexamined Patent Publication No. 2011-204592

However, the binder for electrodes as disclosed in Patent Documents 1 to 6 is a new active material typified by a silicon material having a large amount of lithium occlusion and a large volume change due to occlusion and release of lithium. Adhesion was not sufficient for practical use. When such an electrode binder is used, the electrode deteriorates due to the active material falling off due to repeated charging and discharging, so that there is a problem that the durability required for practical use cannot be sufficiently obtained.

Therefore, some aspects of the present invention provide a binder composition for a power storage device capable of producing a power storage device electrode which is excellent in flexibility and adhesion and exhibits good charge / discharge durability characteristics. In addition, some aspects of the present invention provide a slurry for a power storage device electrode containing the composition. In addition, some aspects of the present invention provide a power storage device electrode that is excellent in flexibility and adhesion and exhibits good charge / discharge durability characteristics. Further, some aspects of the present invention provide a power storage device having excellent charge / discharge durability characteristics.

The present invention has been made to solve at least a part of the above-mentioned problems, and can be realized as any of the following aspects.

One aspect of the composition for a power storage device according to the present invention is
Containing the polymer (A) and the liquid medium (B),
When the total of the repeating units contained in the polymer (A) is 100 parts by mass, the polymer (A) is:
The repeating unit (a1) derived from the compound having a cyclic carbonate group is 1 to 50 parts by mass.
A repeating unit derived from an unsaturated carboxylic acid (a2), a repeating unit derived from (meth) acrylamide (a3), a repeating unit derived from a compound having a sulfo group (a4), and a repeating unit derived from a compound having a hydroxyl group. At least one repeating unit selected from the group consisting of (a5) is 50 to 99 parts by mass.
Contains.

In one aspect of the composition for a power storage device,
The pH may be 5-11.

In any of the above-mentioned compositions for power storage devices,
The viscosity of the 10% by mass aqueous solution of the polymer (A) at pH 9 may be 200,000 to 200,000 mPa · s.

In any of the above-mentioned compositions for power storage devices,
The liquid medium (B) may be water.

One aspect of the slurry for power storage device electrodes according to the present invention is
The composition for a power storage device according to any one of the above embodiments,
At least one polymer (C) selected from the group consisting of a styrene-butadiene copolymer, an acrylic polymer, and a fluorine-based polymer, and
Contains.

In one aspect of the storage device electrode slurry,
The polymer (A) may be contained in an amount of 5 to 100 parts by mass with respect to 100 parts by mass of the polymer (C).

In any aspect of the energy storage device electrode slurry,
In addition, it may contain an active material.

In any aspect of the energy storage device electrode slurry,
A silicon material may be contained as the active material.

In any aspect of the energy storage device electrode slurry,
In addition, it may contain a thickener.

One aspect of the power storage device electrode according to the present invention is
A current collector and an active material layer formed by applying and drying a slurry for a power storage device electrode according to any one of the above on the surface of the current collector are provided.

One aspect of the power storage device according to the present invention is
The storage device electrode of the above-described embodiment is provided.

According to the composition for a power storage device according to the present invention, since flexibility and adhesion can be improved, a power storage device electrode exhibiting good charge / discharge durability characteristics can be manufactured. The composition for a power storage device according to the present invention exerts the above-mentioned effect particularly when the power storage device electrode contains a material having a large lithium occlusion as an active material, for example, a carbon material such as graphite or a silicon material. As described above, since a material having a large lithium occlusion can be used as the active material of the power storage device electrode, the battery performance is also improved.

Hereinafter, preferred embodiments according to the present invention will be described in detail. It should be noted that the present invention is not limited to the embodiments described below, but should be understood to include various modifications implemented without changing the gist of the present invention.

Note that "(meth) acrylic acid-" in the present specification is a concept that includes both "acrylic acid-" and "methacrylic acid-". Similarly, "-(meth) acrylate" is a concept that includes both "-acrylate" and "-methacrylate". Similarly, "(meth) acrylamide" is a concept that includes both "acrylamide" and "methacrylamide".

In the present specification, the numerical range described as "AB" is interpreted as including the numerical value A as the lower limit value and the numerical value B as the upper limit value.

1. 1. Composition for power storage device The composition for power storage device according to one embodiment of the present invention contains a polymer (A) and a liquid medium (B), and is a repeating unit contained in the polymer (A). When the total is 100 parts by mass, the polymer (A) has 1 to 50 parts by mass of a repeating unit (a1) derived from a compound having a cyclic carbonate group, and a repeating unit derived from an unsaturated carboxylic acid (a repeating unit (a1). It is selected from the group consisting of a2), a repeating unit derived from (meth) acrylamide (a3), a repeating unit derived from a compound having a sulfo group (a4), and a repeating unit derived from a compound having a hydroxyl group (a5). It contains at least one repeating unit of 50 to 99 parts by mass.

The composition for a power storage device according to the present embodiment is for producing a power storage device electrode (active material layer) having improved binding ability between active materials, adhesion ability between the active material and a current collector, and powder drop resistance. It can be used as a material, or it can be used as a material for forming a protective film for suppressing a short circuit caused by dendrites generated during charging and discharging. Hereinafter, each component contained in the composition for a power storage device according to the present embodiment will be described in detail.

1.1. Polymer (A)
The composition for a power storage device according to this embodiment contains a polymer (A). The polymer (A) is a repeating unit (a1) derived from a compound having a cyclic carbonate group, assuming that the total of the repeating units contained in the polymer (A) is 100 parts by mass (hereinafter, simply "repeating unit"). (A1) ”) is derived from 1 to 50 parts by mass, a repeating unit (a2) derived from an unsaturated carboxylic acid (hereinafter, also simply referred to as a“ repeating unit (a2) ”), and (meth) acrylamide. Repeat unit (a3) (hereinafter, also simply referred to as "repeating unit (a3)"), repeating unit (a4) derived from a compound having a sulfo group (hereinafter, also simply referred to as "repeating unit (a4)"). , And at least one repeating unit selected from the group consisting of repeating units (a5) derived from a compound having a hydroxyl group (hereinafter, also simply referred to as “repeating unit (a5)”) is 50 to 99 parts by mass. Contains.

Further, the polymer (A) may contain a repeating unit derived from another monomer copolymerizable therewith, in addition to the repeating unit. Examples of other monomers include unsaturated carboxylic acid esters, conjugated diene compounds, aromatic vinyl compounds, α, β-unsaturated nitrile compounds, and cationic monomers.

The polymer (A) contained in the composition for a power storage device according to the present embodiment may be in the form of latex dispersed in the liquid medium (B), or may be in a state of being dissolved in the liquid medium (B). However, it is preferably in a state of being dissolved in the liquid medium (B). When the polymer (A) is dissolved in the liquid medium (B), the slurry for a power storage device (hereinafter, also simply referred to as “slurry”) produced by mixing with an active material or an inorganic filler is stable. It is preferable because the property is good and the property of the slurry to be applied to the current collector is good.

Hereinafter, each repeating unit constituting the polymer (A), the physical properties of the polymer (A), and the production method will be described in this order.

1.1.1. Repeating unit constituting the polymer (A) 1.1.1.1. Repeating unit (a1) derived from a compound having a cyclic carbonate group
The content ratio of the repeating unit (a1) derived from the compound having a cyclic carbonate group is 1 to 50 parts by mass when the total of the repeating units contained in the polymer (A) is 100 parts by mass. The lower limit of the content ratio of the repeating unit (a1) is preferably 2 parts by mass, more preferably 5 parts by mass, further preferably 7 parts by mass, and particularly preferably 10 parts by mass. preferable. The upper limit of the content ratio of the repeating unit (a1) is preferably 48 parts by mass, more preferably 45 parts by mass, and particularly preferably 40 parts by mass. By containing the repeating unit (a1) in the above range, the active material can be coated with the polymer (A) having a cyclic carbonate group, and a good film is formed on the surface of the active material due to the decomposition of the cyclic carbonate group during charging. Since it is formed, decomposition of the electrolytic solution component can be suppressed, and depletion of the electrolytic solution can be prevented, the capacity retention rate when the charge / discharge cycle is carried out becomes good. Further, since the polymer (A) having a low glass transition temperature can exist in the state of an aqueous solution, the dispersibility of the active material and the filler becomes good. Further, since the polymer (A) becomes excellent in flexibility, it is possible to suppress the occurrence of structural defects of the electrode plate by expanding and contracting even if the polymer (A) coats the active material, and has good charge / discharge durability. Shows the characteristics.

The compound having a cyclic carbonate group is not particularly limited, and examples thereof include a compound represented by the following general formula (1) and a compound represented by the following general formula (2).

In the general formula (1) and the above general formula (2), R ¹ represents a hydrogen atom or a methyl group. R ² represents a single bond or a divalent linking group. R ³ represents a monovalent organic group having a cyclic carbonate structure.

Examples of R ³ include groups represented by the following general formula (3) or the following general formula (4).

In the general formula (3) and the general formula (4), n1 represents an integer of 0 to 2, n2 to n5 independently represent an integer of 0 to 2, and "*" represents the general formula (1). Alternatively, it represents a bond that binds to ^{R 2} in the above general formula (2). Further, the groups represented by the general formula (3) and the general formula (4) may have a substituent.

As a specific example of the group represented by the above general formula (3), a group represented by the following formula (5) can be mentioned. Specific examples of the group represented by the general formula (4) include a group represented by the following formula (6).

Among these compounds, the compound represented by the following general formula (7) or the following general formula (8) is preferable.

In the general formula (7) and the above general formula (8), R ¹ represents a hydrogen atom or a methyl group.

1.1.1.2. Repeating unit derived from unsaturated carboxylic acid (a2)
The polymer (A) can contain a repeating unit (a2) derived from an unsaturated carboxylic acid. The content ratio of the repeating unit (a2) derived from the unsaturated carboxylic acid is preferably 5 to 90 parts by mass when the total of the repeating units contained in the polymer (A) is 100 parts by mass. The lower limit of the content ratio of the repeating unit (a2) is preferably 7 parts by mass, more preferably 10 parts by mass. The upper limit of the content ratio of the repeating unit (a2) is preferably 85 parts by mass, more preferably 80 parts by mass. By containing the repeating unit (a2) in the above range, the dispersibility of the active material and the filler becomes good. Further, it exhibits good charge / discharge durability characteristics by improving the affinity with the silicon material as an active material and suppressing the swelling of the silicon material.

The unsaturated carboxylic acid is not particularly limited, and examples thereof include mono- or dicarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, and itaconic acid, and one or more selected from these. There can be.

1.1.1.3. Repeat unit derived from (meth) acrylamide (a3)
The polymer (A) can contain a repeating unit (a3) derived from (meth) acrylamide. The content ratio of the repeating unit (a3) derived from (meth) acrylamide is preferably 5 to 90 parts by mass when the total of the repeating units contained in the polymer (A) is 100 parts by mass. The lower limit of the content ratio of the repeating unit (a3) is preferably 7 parts by mass, more preferably 10 parts by mass. The upper limit of the content ratio of the repeating unit (a3) is preferably 85 parts by mass, more preferably 80 parts by mass. By containing the repeating unit (a3) in the above range, the glass transition degree (Tg) of the polymer (A) becomes suitable, and as a result, the dispersibility of the active material and the filler becomes good. In addition, the flexibility of the obtained active material layer becomes appropriate, and the adhesion ability between the current collector and the active material layer becomes good. Further, since the bonding ability between the active materials containing the carbon material such as graphite and the silicon material can be enhanced, the obtained active material layer has better flexibility and adhesion to the current collector. ..

The (meth) acrylamide is not particularly limited, but is limited to acrylamide, methacrylamide, N-isopropylacrylamide, N, N-dimethylacrylamide, N, N-dimethylmethacrylicamide, N, N-diethylacrylamide, N, N-diethylmethacryl. Examples thereof include amide, N, N-dimethylaminopropyl acrylamide, N, N-dimethylaminopropyl methacrylamide, N-methylol methacrylamide, N-methylol acrylamide, diacetone acrylamide, maleic acid amide, acrylamide tert-butyl sulfonic acid and the like. .. These (meth) acrylamides may be used alone or in combination of two or more.

1.1.1.4. Repeating unit (a4) derived from a compound having a sulfo group
The polymer (A) can contain a repeating unit (a4) derived from a compound having a sulfo group. Here, since the compound having a sulfo group has an ethylenically unsaturated group that contributes to the polymerization reaction, strictly speaking, it is a compound having an ethylenically unsaturated group and a sulfo group.

The content ratio of the repeating unit (a4) derived from the compound having a sulfo group is preferably 5 to 90 parts by mass when the total of the repeating units contained in the polymer (A) is 100 parts by mass. .. The lower limit of the content ratio of the repeating unit (a4) is preferably 7 parts by mass, more preferably 10 parts by mass. The upper limit of the content ratio of the repeating unit (a4) is preferably 85 parts by mass, more preferably 80 parts by mass. By containing the repeating unit (a4) in the above range, the glass transition temperature (Tg) of the polymer (A) becomes suitable, and as a result, the dispersibility of the active material and the filler becomes good. In addition, the flexibility of the obtained active material layer becomes appropriate, and the adhesion ability between the current collector and the active material layer becomes good. Further, since the bonding ability between the active materials containing the carbon material such as graphite and the silicon material can be enhanced, the obtained active material layer has better flexibility and adhesion to the current collector. ..

Specific examples of the compound having a sulfo group are not particularly limited, but vinyl sulfonic acid, styrene sulfonic acid, allyl sulfonic acid, sulfoethyl (meth) acrylate, sulfopropyl (meth) acrylate, sulfobutyl (meth) acrylate, 2-acrylamide. Compounds having a sulfonic acid group such as -2-methylpropanesulfonic acid, 2-hydroxy-3-acrylamidepropanesulfonic acid, 3-allyloxy-2-hydroxypropanesulfonic acid, and alkali salts thereof may be used.

1.1.1.5. Repeating unit (a5) derived from a compound having a hydroxyl group
The polymer (A) can contain a repeating unit (a5) derived from a compound having a hydroxyl group. Here, since the compound having a hydroxyl group has an ethylenically unsaturated group that contributes to the polymerization reaction, strictly speaking, it is a compound having an ethylenically unsaturated group and a hydroxyl group.

The content ratio of the repeating unit (a5) derived from the compound having a hydroxyl group is preferably 5 to 90 parts by mass when the total of the repeating units contained in the polymer (A) is 100 parts by mass. The lower limit of the content ratio of the repeating unit (a5) is preferably 7 parts by mass, more preferably 10 parts by mass. The upper limit of the content ratio of the repeating unit (a5) is preferably 85 parts by mass, more preferably 80 parts by mass. By containing the repeating unit (a5) in the above range, the glass transition temperature (Tg) of the polymer (A) becomes suitable, and as a result, the dispersibility of the active material and the filler becomes good. In addition, the flexibility of the obtained active material layer becomes appropriate, and the adhesion ability between the current collector and the active material layer becomes good. Further, since the bonding ability between the active materials containing the carbon material such as graphite and the silicon material can be enhanced, the obtained active material layer has better flexibility and adhesion to the current collector. ..

Specific examples of the compound having a hydroxyl group are not particularly limited, but are 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. , 5-Hydroxypentyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, glycerin mono (meth) acrylate, glycerin di (meth) acrylate and other unsaturated carboxylic acid esters; vinyl alcohol, 2-vinylphenol, 3- Examples thereof include vinylphenol and 4-vinylphenol. Among these, 2-hydroxyethyl (meth) acrylate and glycerin mono (meth) acrylate are preferable. In addition, these monomers can be used individually by 1 type or in combination of 2 or more types.

1.1.1.6. Content ratio of repeating units (a2) to (a5) The polymer (A) has a repeating unit (a2) and a repeating unit (a2) when the total of the repeating units contained in the polymer (A) is 100 parts by mass. It contains 50 to 99 parts by mass of at least one repeating unit selected from the group consisting of a3), a repeating unit (a4) and a repeating unit (a5). The lower limit of the content ratio of the repeating units (a2) to (a5) is preferably 55 parts by mass, more preferably 60 parts by mass. The upper limit of the content ratio of the repeating units (a2) to (a5) is preferably 95 parts by mass, more preferably 90 parts by mass. By containing the repeating units (a2) to (a5) in the above range, the glass transition temperature (Tg) of the polymer (A) becomes more suitable, and an electrode plate having excellent flexibility can be produced. As a result, an electrode plate having excellent charge / discharge durability characteristics can be obtained. Further, the affinity between the polymer (A) and the active material or filler becomes better, and a slurry having better dispersibility of the active material or filler can be obtained.

11.1.7. Other Repeating Units The polymer (A) may contain repeating units derived from other monomers copolymerizable with the repeating units (a1) to (a5) in addition to the repeating units (a1) to (a5). Such a repeating unit is a repeating unit derived from an unsaturated carboxylic acid ester (excluding those corresponding to the repeating units (a1) to (a5). Hereinafter, it is also simply referred to as “repeating unit (a6)”). , The repeating unit (a7) derived from the conjugated diene compound (hereinafter, also simply referred to as “repeating unit (a7)”), the repeating unit (a8) derived from the aromatic vinyl compound (hereinafter, simply “repeating unit (a8)). ”), Repeating unit (a9) derived from α, β-unsaturated nitrile compound (hereinafter, also simply referred to as“ repeating unit (a9) ”), repeating unit derived from cationic monomer (hereinafter, also referred to as“ repeating unit ”). , Simply referred to as "repeating unit (a10)") and the like.

The unsaturated carboxylic acid ester is not particularly limited, but a (meth) acrylic acid ester is preferable. Specific examples of the (meth) acrylic acid ester include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, and n-butyl (meth) acrylate. , (Meta) isobutyl acrylate, (meth) n-amyl acrylate, (meth) isoamyl acrylate, (meth) hexyl acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (meth) Examples thereof include n-octyl acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, and allyl (meth) acrylate, and one or more of these can be selected. Of these, one or more selected from methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, cyclohexyl (meth) acrylate and 2-ethylhexyl (meth) acrylate. It is preferably present, and particularly preferably methyl (meth) acrylate.

The conjugated diene compound is not particularly limited, but 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-chlor-1,3-butadiene and the like can be used. It can be listed and can be one or more selected from these. Of these, 1,3-butadiene is particularly preferable.

The aromatic vinyl compound is not particularly limited, and examples thereof include styrene, α-methylstyrene, p-methylstyrene, vinyltoluene, chlorostyrene, and divinylbenzene, and one or more selected from these can be used. There can be. Of these, styrene is particularly preferable.

The α, β-unsaturated nitrile compound is not particularly limited, and examples thereof include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethylacrylonitrile, vinylidene cyanide, and the like, and are selected from these 1 Can be more than a seed. Of these, one or more selected from acrylonitrile and methacrylonitrile is preferable, and acrylonitrile is particularly preferable.

The cationic monomer is not particularly limited, but is at least one monomer selected from the group consisting of a secondary amine (salt), a tertiary amine (salt) and a quaternary ammonium salt. Is preferable. Specific examples of these cationic monomers are not particularly limited, but are 2- (dimethylamino) ethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate methyl quaternary chloride quaternary salt, and 2- (meth) acrylate. (Diethylamino) ethyl, 3- (dimethylamino) propyl (meth) acrylate, 3- (diethylamino) propyl (meth) acrylate, 4- (dimethylamino) phenyl (meth) acrylate, 2- (meth) acrylate [(3,5-Dimethylpyrazolyl) carbonylamino] ethyl, (meth) acrylate 2- (0- [1'-methylpropyridaneamino] carboxyamino) ethyl, (meth) acrylate 2- (1-aziridinyl) Ethyl, metachlorocholine chloride, tris isocyanurate (2-acryloyloxyethyl), 2-vinylpyridine, quinaldine red, 1,2-di (2-pyridyl) ethylene, 4'-hydrazino-2-stilbazole dihydrochloride water Japanese product, 4- (4-dimethylaminostyryl) quinoline, 1-vinylimidazole, diallylamine, diallylamine hydrochloride, triallylamine, diallyldimethylammonium chloride, dichloromid, N-allylbenzylamine, N-allylaniline, 2,4- Diamino-6-diallylamino-1,3,5-triazine, N-trans-cinnamyl-N-methyl- (1-naphthylmethyl) amine hydrochloride, trans-N- (6,6-dimethyl-2-heptene-) 4-Inyl) -N-methyl-1-naphthylmethylamine hydrochloride and the like can be mentioned. These monomers may be used alone or in combination of two or more.

The polymer (A) has a repeating unit (a6), a repeating unit (a7), a repeating unit (a8), and a repeating unit (a6), assuming that the total of the repeating units contained in the polymer (A) is 100 parts by mass. It is preferable to contain 20 parts by mass or less of a9) and the repeating unit (a10) in total. The content ratio of the repeating units (a6) to (a10) is more preferably 0 to 15 parts by mass, and particularly preferably 0 to 10 parts by mass.

1.1.2. Physical characteristics of polymer (A) <Solubility in water>
The polymer (A) is preferably a water-soluble polymer. The "water-soluble polymer" in the present invention refers to a polymer having a solubility in water at 25 ° C. and 1 atm of 1 g or more with respect to 100 g of water. When the polymer (A) is a water-soluble polymer, the surface of the active material is easily coated by the polymer (A) having excellent flexibility and adhesion, so that the active material can be effectively removed by expansion and contraction during charging and discharging. It is easy to obtain a power storage device that can be effectively suppressed and exhibits good charge / discharge durability characteristics. Further, the stability of the slurry is improved, and the applicability of the slurry to the current collector is also improved, which is preferable.

<Viscosity>
The viscosity of the 10% by mass aqueous solution of the polymer (A) at pH 9 is preferably 20 to 200,000 mPa · s, more preferably 50 to 150,000 mPa · s, and 1,000 to 150, It is particularly preferably 000 mPa · s. When the viscosity of the 10% by mass aqueous solution of the polymer (A) at pH 9 is in the above range, the dispersibility of the active material and the filler becomes good, and a uniform active material layer and a protective film can be easily formed. As a result, an electrode or the like having no structural defects can be obtained, which is preferable because it exhibits good charge / discharge characteristics.

The viscosity of the 10% by mass aqueous solution of the polymer (A) is a value measured at a temperature of 25.0 ° C. using a B-type viscometer in accordance with JIS Z8803. As the B-type viscometer, for example, "RB-80L" or "TVB-10" manufactured by Toki Sangyo Co., Ltd. can be used.

<Number average molecular weight (Mn)>
The number average molecular weight (Mn) of the polymer (A) is preferably 10,000 or more and 2,000,000 or less, more preferably 50,000 or more and 1,500,000 or less, and particularly preferably 100, It is 000 or more and 1,000,000 or less. When the number average molecular weight (Mn) of the polymer (A) is within the above range, the adhesion is good and it is easy to obtain a power storage device having excellent charge / discharge characteristics. The number average molecular weight of the polymer (A) can be measured, for example, by using the GPC method under the following conditions.
(Measurement condition)
-Measuring equipment: GPC (model number: HLC-8220) manufactured by Tosoh Corporation
-Column: TSKgel guardcolum PW _XL (manufactured by Tosoh Co., Ltd.), TSK-GEL G2500PW _XL (manufactured by Tosoh Co., Ltd.), TSK-GEL GMPW _XL (manufactured by Tosoh Co., Ltd.)
-Eluent: 0.1 M NaNO ₃ aqueous solution-Calibration curve: Standard polyethylene oxide-Measurement method: Dissolve the polymer (A) in the eluent so that the solid content is 0.3 wt%, and measure after filtering.

<Glass transition temperature>
The polymer (A) preferably has only one endothermic peak in the temperature range of 60 ° C. to 160 ° C. as measured by differential scanning calorimetry (DSC) according to JIS K 7121. The temperature of this endothermic peak (that is, the glass transition temperature (Tg)) is more preferably in the range of 70 ° C. to 150 ° C. When the polymer (A) has only one endothermic peak in the DSC analysis and the peak temperature is in the above range, the polymer (A) exhibits good adhesion and has good adhesion to the active material layer. It is preferable because it can impart better flexibility and adhesiveness.

11.3. Method for Producing Polymer (A) The method for producing the polymer (A) is not particularly limited, but for example, polymerization performed in a solvent containing water as a main component in the presence of a known chain transfer agent, polymerization initiator, or the like can be performed. preferable. The polymer (A) may be synthesized by one-step polymerization, two-step polymerization or multi-step polymerization, and a polymerization initiator, a molecular weight modifier, an emulsifier (surfactant) and the like known in each polymerization. Can be synthesized in the presence of. As for the amount and type of the polymerization initiator, the molecular weight adjusting agent, the emulsifier (surfactant) and the like, and the synthesis method, the components and methods described in Japanese Patent No. 5477610 and the like can be used.

The pH may be adjusted to 5 to 11 by adding a neutralizing agent to the polymerization mixture obtained by the above synthesis method. The neutralizing agent used here is not particularly limited, and examples thereof include metal hydroxides such as sodium hydroxide and potassium hydroxide; ammonia and the like. By adjusting to the above pH range, the polymer (A) can be dissolved in the liquid medium (B) to thicken it. Further, by concentrating the polymerization mixture after the neutralization treatment, the solid content concentration can be increased while maintaining the good stability of the polymer (A).

A slurry for a power storage device is prepared using the composition for a power storage device as it is without adding a neutralizer to the polymerization mixture obtained by the above synthesis method, and then a neutralizer is added to the slurry for the power storage device. It may be added to increase the viscosity by adjusting the pH to 5-11. In this case, since the composition for the power storage device is not thickened, it may be easy to prepare the slurry for the power storage device.

1.2. Liquid medium (B)
The composition for a power storage device according to the present embodiment contains a liquid medium (B). The liquid medium (B) is preferably an aqueous medium containing water, and more preferably water. The aqueous medium may contain a non-aqueous medium other than water. Examples of this non-aqueous medium include amide compounds, hydrocarbons, alcohols, ketones, esters, amine compounds, lactones, sulfoxides, sulfone compounds, and the like, and one or more selected from these may be used. Can be done. By using an aqueous medium as the liquid medium (B) in the composition for a power storage device according to the present embodiment, the degree of adverse effect on the environment is reduced, and the safety for the handling operator is also increased.

The content ratio of the non-aqueous medium contained in the aqueous medium is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and particularly preferably not substantially contained in 100 parts by mass of the aqueous medium. preferable. Here, "substantially free" means that a non-aqueous medium is not intentionally added as a liquid medium, and the non-aqueous medium is inevitably mixed when preparing a composition for a power storage device. May include.

1.3. Other Additives The composition for a power storage device according to the present embodiment may contain additives other than the above-mentioned components, if necessary. Examples of such additives include polymers other than the polymer (A), preservatives, thickeners and the like.

<Polymer other than polymer (A)>
The composition for a power storage device according to the present embodiment may contain a polymer other than the polymer (A) (hereinafter, also referred to as “polymer (C)”). Such a polymer (C) is not particularly limited, but is an acrylic polymer containing a styrene-butadiene copolymer such as SBR (styrene butadiene rubber), an unsaturated carboxylic acid ester or a derivative thereof as a constituent unit. Fluorine-based polymers such as PVDF (polyvinylidene fluoride) and the like can be mentioned. These polymers (C) may be used alone or in combination of two or more. By containing the polymer (C), flexibility and adhesion may be further improved.

The content ratio of the polymer (A) in the composition for a power storage device according to the present embodiment is 1 to 70 parts by mass with respect to 100 parts by mass in total of the polymer (A), the polymer (C) and the thickener. It is preferably 1 to 40 parts by mass, and particularly preferably 2 to 10 parts by mass.

When the composition for a power storage device according to the present embodiment contains the polymer (C), the content ratio of the polymer (A) is 5 to 100 parts by mass with respect to 100 parts by mass of the polymer (C). It is preferably 10 to 80 parts by mass, and particularly preferably 10 to 60 parts by mass. By setting the content ratio of the polymer (A) and the polymer (C) within the above range, flexibility and adhesion may be effectively improved, and the amount of lithium stored as an active material is particularly large. When a material such as a carbon material such as graphite or a silicon material is used, it may be possible to manufacture a power storage device electrode exhibiting good charge / discharge durability characteristics.

<Preservative>
The composition for a power storage device according to the present embodiment may contain a preservative. By containing the preservative, it may be possible to suppress the growth of bacteria, mold and the like to generate foreign substances when the composition for a power storage device is stored. Specific examples of the preservative include compounds described in Japanese Patent No. 5477610.

<Thickener>
The composition for a power storage device according to the present embodiment may contain a thickener. By containing the thickener, the coatability thereof and the charge / discharge characteristics of the obtained power storage device may be further improved.

Specific examples of the thickener include cellulose compounds such as carboxymethyl cellulose, methyl cellulose, and hydroxypropyl cellulose; poly (meth) acrylic acid; the cellulose compound or the ammonium salt or alkali metal salt of the poly (meth) acrylic acid; polyvinyl. Polyvinyl alcohol-based (co) polymers such as alcohol, modified polyvinyl alcohol, and ethylene-vinyl alcohol copolymers; copolymers of unsaturated carboxylic acids such as (meth) acrylic acid, maleic acid, and fumaric acid and vinyl esters. Examples thereof include water-soluble polymers such as saponified products. Among these, alkali metal salts of carboxymethyl cellulose, alkali metal salts of poly (meth) acrylic acid and the like are preferable.

When the composition for a power storage device according to the present embodiment contains a thickener, the content ratio of the thickener shall be 5 parts by mass or less with respect to 100 parts by mass of the total solid content of the composition for a power storage device. Is preferable, and 0.1 to 3 parts by mass is more preferable.

1.4. PH of composition for power storage device
The pH of the composition for a power storage device according to the present embodiment is preferably 5 to 11, more preferably 6 to 11, and particularly preferably 7 to 10.5. When the pH is within the above range, the polymer (A) dissolves in the liquid medium (B), so that the viscosity of the composition for a power storage device can be increased. As a result, it is possible to suppress the occurrence of problems such as insufficient leveling property and liquid dripping when applying the slurry, and it is easy to manufacture a power storage device electrode having both good electrical characteristics and adhesion. Become. It also improves the stability of the slurry.

"PH" in the present specification refers to physical properties measured as follows. It is a value measured in accordance with JIS Z8802: 2011 with a pH meter using a glass electrode calibrated with a neutral phosphate standard solution and a borate standard solution as a pH standard solution at 25 ° C. Examples of such a pH meter include "HM-7J" manufactured by DKK-TOA CORPORATION and "D-51" manufactured by HORIBA, Ltd.

It should be noted that the pH of the composition for a power storage device is affected by the monomer composition constituting the polymer (A), but it is not determined only by the monomer composition. That is, it is generally known that the pH of the composition for a power storage device changes depending on the polymerization conditions and the like even if the monomer composition is the same, and the examples of the present specification show only one example. No.

For example, even if the polymer composition is the same, all the unsaturated carboxylic acids are charged into the polymerization reaction solution from the beginning, and then other monomers are added in sequence, or a monomer other than the unsaturated carboxylic acid is added. The amount of carboxyl groups derived from the unsaturated carboxylic acid exposed on the surface of the obtained polymer is different from that in the case of charging the polymerization reaction solution and finally adding the unsaturated carboxylic acid. It is considered that the pH of the composition for a power storage device is significantly different even if the order in which the monomers are added is changed by the polymerization method.

2. Slurry for power storage device The slurry for power storage device according to the embodiment of the present invention contains the above-mentioned composition for power storage device. As described above, the composition for a power storage device according to the present embodiment can be used as a material for forming a protective film for suppressing a short circuit caused by dendrites generated during charging and discharging. It can also be used as a material for producing a power storage device electrode (active material layer) having improved binding ability between active materials, adhesion ability between the active material and a current collector, and powder drop resistance. Therefore, a slurry for a power storage device for forming a protective film (hereinafter, also referred to as a “slurry for forming a protective film”) and a slurry for a power storage device for forming an active material layer of a power storage device electrode (hereinafter, “storage”). It is also referred to as "device electrode slurry").

2.1. Slurry for forming a protective film The term "slurry for forming a protective film" as used herein refers to a slurry for forming a protective film, which is applied to the surface of an electrode or a separator or both, and then dried to apply a protective film to the surface of an electrode or a separator or both. A solution or dispersion used to form. The slurry for forming a protective film according to the present embodiment may be composed only of the above-mentioned composition for a power storage device, or may further contain an inorganic filler. Hereinafter, each component contained in the protective film forming slurry according to the present embodiment will be described in detail. Since the composition for the power storage device is as described above, the description thereof will be omitted.

2.1.1. Inorganic filler The slurry for forming a protective film according to the present embodiment can improve the toughness of the protective film formed by containing the inorganic filler. As the inorganic filler, it is preferable to use at least one kind of particles selected from the group consisting of silica, titanium oxide (titania), aluminum oxide (alumina), zirconium oxide (zirconia), and magnesium oxide (magnesia). Among these, titanium oxide and aluminum oxide are preferable from the viewpoint of further improving the toughness of the protective film. Further, as the titanium oxide, rutile type titanium oxide is more preferable.

The average particle size of the inorganic filler is preferably 1 μm or less, more preferably 0.1 to 0.8 μm. The average particle size of the inorganic filler is preferably larger than the average pore size of the separator which is a porous film. This can reduce damage to the separator and prevent the inorganic filler from clogging the microporous separator.

The slurry for forming a protective film according to the present embodiment preferably contains 0.1 to 20 parts by mass of the above-mentioned composition for a power storage device in terms of solid content with respect to 100 parts by mass of the inorganic filler. More preferably, it is contained in an amount of about 10 parts by mass. When the content ratio of the composition for the power storage device is within the above range, the balance between the toughness of the protective film formed and the permeability of lithium ions is good, and as a result, the resistance increase rate of the obtained power storage device is lowered. can do.

2.1.2. Liquid medium The slurry for forming a protective film according to the present embodiment may further contain a liquid medium, and is described in the section "1.2. Liquid medium (B)" of the above-mentioned composition for a power storage device. The material can be used as needed. The amount of the liquid medium added can be adjusted as necessary so that the optimum viscosity of the slurry can be obtained according to the coating method and the like.

2.1.3. Other Ingredients For the protective film-forming slurry according to the present embodiment, an appropriate amount of the material described in the section "1.3. Other additives" of the above-mentioned composition for power storage device may be used as needed. can.

2.2. Slurry for power storage device electrodes The term "slurry for power storage device electrodes" as used herein is used to apply this to the surface of a current collector and then dry it to form an active material layer on the surface of the current collector. It refers to the dispersion liquid that is produced. The slurry for a power storage device electrode according to the present embodiment contains the above-mentioned composition for a power storage device and an active material.

In general, a slurry for a power storage device electrode often contains a binder component such as an SBR-based copolymer and a thickener such as carboxymethyl cellulose in order to improve adhesion. On the other hand, the slurry for the power storage device electrode according to the present embodiment can improve the flexibility and the adhesiveness only by the above-mentioned polymer (A). Of course, the slurry for the power storage device electrode according to the present embodiment may contain a polymer other than the polymer (A) or a thickener in order to further improve the adhesion.

2.2.1. Polymer (A)
The composition, properties, and production method of the polymer (A) are as described above, and thus the description thereof will be omitted. The content ratio of the polymer (A) in the slurry for the power storage device electrode according to the present embodiment is preferably 1 to 8 parts by mass and 1 to 7 parts by mass with respect to 100 parts by mass of the active material. It is more preferably 1.5 to 6 parts by mass, and particularly preferably 1.5 to 6 parts by mass. When the content ratio of the polymer (A) is within the above range, the dispersibility of the active material in the slurry becomes good, and the coatability of the slurry becomes also excellent. The same applies when the slurry for the power storage device electrode according to the present embodiment contains a polymer other than the polymer (A) or a thickener.

2.2.2. Active material Examples of the active material used in the slurry for the power storage device electrode according to the present embodiment include a carbon material, a silicon material, an oxide containing a lithium atom, a lead compound, a tin compound, an arsenic compound, an antimony compound, and an aluminum compound. Can be mentioned. Specific examples of these include compounds described in Japanese Patent No. 5999399.

Further, the active material layer may contain the active material exemplified below. For example conductive polymers such as polyacene; A X _B Y _O Z _(where, A is an alkali metal or a transition metal, B is cobalt, nickel, aluminum, tin, at least one selected from the transition metals manganese, O Represents an oxygen atom, where X, Y and Z are numbers in the range 1.10>X> 0.05, 4.00>Y> 0.85 and 5.00>Z> 1.5, respectively.) Examples thereof include composite metal oxides represented by and other metal oxides.

The slurry for the power storage device electrode according to the present embodiment can be used when producing any power storage device electrode of the positive electrode and the negative electrode, and is preferably used for both the positive electrode and the negative electrode.

When lithium iron phosphate was used as the positive electrode active material, there was a problem that the charge / discharge characteristics were not sufficient and the adhesion was inferior. Lithium iron phosphate has a fine primary particle size and is known to be a secondary aggregate thereof. When charging and discharging are repeated, the aggregation collapses in the active material layer and the active materials are separated from each other. It is considered that one of the causes is that it is easily peeled off from the current collector and the conductive network inside the active material layer is easily broken.

However, the power storage device electrode produced by using the slurry for the power storage device electrode according to the present embodiment exhibits good electrical characteristics without causing the above-mentioned problems even when lithium iron phosphate is used. be able to. The reason for this is that the polymer (A) can firmly bind lithium iron phosphate, and at the same time, it can maintain a state in which lithium iron phosphate is firmly bound even during charging and discharging. it is conceivable that.

On the other hand, when producing a negative electrode, it is preferable that the active material exemplified above contains a silicon material. Since the silicon material has a large occlusion amount of lithium per unit weight as compared with other active materials, the storage capacity of the obtained power storage device can be increased by containing the silicon material as the negative electrode active material. As a result, the output and energy density of the power storage device can be increased.

Further, the negative electrode active material is more preferably a mixture of a silicon material and a carbon material. Since the volume change of the carbon material due to charge and discharge is small, the influence of the volume change of the silicon material can be mitigated by using a mixture of the silicon material and the carbon material as the negative electrode active material, and the active material layer and the collection. The ability to adhere to the electric body can be further improved.

When silicon (Si) is used as an active material, silicon has a high capacity, but causes a large volume change when it occludes lithium. For this reason, the silicon material has a property that the conductive network inside the active material layer is easily broken by causing micronization, peeling from the current collector, and peeling between the active materials by repeating expansion and contraction. As a result, the cycle characteristics are extremely deteriorated in a short time.

However, the power storage device electrode produced by using the slurry for the power storage device electrode according to the present embodiment can exhibit good electrical characteristics without causing the above-mentioned problems even when a silicon material is used. can. The reason for this is that the polymer (A) can firmly bind the silicon material, and at the same time, the polymer (A) expands and contracts even if the silicon material expands in volume due to occlusion of lithium, resulting in silicon. It is considered that this is because the material can be maintained in a tightly bound state.

The content ratio of the silicon material in 100% by mass of the active material is preferably 1% by mass or more, more preferably 1 to 50% by mass, further preferably 5 to 45% by mass, and 10%. It is particularly preferable to set it to 40% by mass. When the content ratio of the silicon material in 100% by mass of the active material is within the above range, a power storage device having an excellent balance between the improvement of the output and energy density of the power storage device and the charge / discharge durability characteristics can be obtained.

The shape of the active material is preferably granular. The average particle size of the active material is preferably 0.1 to 100 μm, more preferably 1 to 20 μm. Here, the average particle size of the active material is a volume average particle size calculated from the particle size distribution measured by using a particle size distribution measuring device based on a laser diffraction method. Examples of such a laser diffraction type particle size distribution measuring device include the HORIBA LA-300 series and the HORIBA LA-920 series (all manufactured by HORIBA, Ltd.).

2.2.3. Other Components In addition to the above-mentioned components, other components may be added to the slurry for the power storage device electrode according to the present embodiment, if necessary. Examples of such components include polymers other than the polymer (A), thickeners, conductivity-imparting agents, liquid media (excluding those brought in from the composition for power storage devices), pH adjusters, and corrosion. Examples include preventive agents. As the polymer and thickener other than the polymer (A), select from the compounds exemplified in the above section "1.3. Other additives" and use them for the same purpose and content ratio. Can be done. Examples of the conductivity-imparting agent include compounds described in Japanese Patent No. 5999399.

<Liquid medium>
The liquid medium that can be additionally added to the slurry for the power storage device electrode according to the present embodiment may be the same as or different from the liquid medium (B) contained in the composition for the power storage device. It is preferable to select and use the liquid medium exemplified in the above section "1.2. Liquid medium (B)".

The ratio of the liquid medium (including the amount brought in from the composition for the power storage device) in the slurry for the power storage device electrode according to the present embodiment is the solid content concentration in the slurry (the total mass of the components other than the liquid medium in the slurry). Refers to the ratio of the slurry to the total mass. The same shall apply hereinafter) is preferably a ratio of 30 to 70% by mass, and more preferably 40 to 60% by mass.

<pH adjuster / corrosion inhibitor>
The slurry for a power storage device electrode according to the present embodiment may contain a pH adjuster and / or a corrosion inhibitor for the purpose of suppressing corrosion of the current collector according to the type of active material.

Examples of the pH adjuster include hydrochloric acid, phosphoric acid, sulfuric acid, acetic acid, formic acid, ammonium phosphate, ammonium sulfate, ammonium acetate, ammonium formate, ammonium chloride, sodium hydroxide, potassium hydroxide and the like. Sulfate, ammonium sulfate, sodium hydroxide and potassium hydroxide are preferred. Further, it can be selected and used from the compounds described in the method for producing the polymer (A).

Corrosion inhibitors include ammonium metavanadate, sodium metavanadate, potassium metavanadate, ammonium metatungstate, sodium metatungstate, potassium metatungstate, ammonium paratungstate, sodium paratungstate, potassium paratungstate, molybdate. Examples thereof include ammonium, sodium molybdate, and potassium molybdate. Among these, ammonium paratungstate, ammonium metavanadate, sodium metavanadate, potassium metavanadate, and ammonium molybdate are preferable.

2.2.4. Method for Preparing Slurry for Power Storage Device Electrode The slurry for power storage device electrode according to the present embodiment is produced by any method as long as it contains the above-mentioned composition for power storage device and an active material. However, it can be produced by the method described in, for example, Japanese Patent No. 5999399.

3. 3. Storage device electrode The power storage device electrode according to an embodiment of the present invention includes a current collector, an active material layer formed by applying and drying the above-mentioned storage device electrode slurry on the surface of the current collector. Is provided. Such a power storage device electrode is formed by applying the above-mentioned slurry for a power storage device electrode to the surface of a current collector such as a metal foil to form a coating film, and then drying the coating film to form an active material layer. Can be manufactured. The power storage device electrode produced in this manner is formed by bonding an active material layer containing the above-mentioned polymer (A), an active material, and an optional component added as needed, on a current collector. Therefore, it is excellent in flexibility and adhesion, and exhibits good charge / discharge durability characteristics.

The current collector is not particularly limited as long as it is made of a conductive material, and examples thereof include the current collector described in Japanese Patent No. 5999399.

There is no particular limitation on the method of applying the slurry for the power storage device electrode to the current collector, and the slurry can be applied by the method described in, for example, Japanese Patent No. 5999399. The power storage device electrode manufactured in this manner is excellent in flexibility and adhesion, and exhibits good charge / discharge durability characteristics.

When a silicon material is used as the active material in the power storage device electrode according to the present embodiment, the content ratio of the silicon element in 100 parts by mass of the active material layer is preferably 2 to 30 parts by mass, and 3 to 25 parts by mass. Is more preferable. When the content of the silicon element in the active material layer is within the above range, in addition to improving the storage capacity of the power storage device produced by using the silicon element, an active material layer having a uniform distribution of silicon elements can be obtained. .. In the present invention, the content of the silicon element in the active material layer can be measured by, for example, the method described in Japanese Patent No. 5999399.

4. Power storage device The power storage device according to the embodiment of the present invention can be manufactured according to a conventional method by providing the above-mentioned power storage device electrode, further containing an electrolytic solution, and using parts such as a separator. As a specific manufacturing method, for example, a negative electrode and a positive electrode are overlapped with each other via a separator, and the negative electrode and the positive electrode are stored in a battery container by winding or folding according to the shape of the battery, and an electrolytic solution is injected into the battery container. The method of sealing the battery can be mentioned. The shape of the battery can be an appropriate shape such as a coin type, a cylindrical type, a square type, or a laminated type.

The electrolytic solution may be in the form of a liquid or a gel, and depending on the type of the active material, a known electrolytic solution used in the power storage device that effectively exhibits the function as a battery may be selected. The electrolytic solution can be a solution in which the electrolyte is dissolved in a suitable solvent. Examples of these electrolytes and solvents include compounds described in Japanese Patent No. 5999399.

5. Examples Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. Unless otherwise specified, "parts" and "%" in Examples and Comparative Examples are based on mass.

5.1. Example 1
5.1.1. Preparation of composition for power storage device and measurement of viscosity (1) Preparation of composition for power storage device In a 100 L autoclave, 900 parts by mass of water, 0.1 part by mass of sodium persulfate, 0.5 part by mass of dodecylbenzene sulfonic acid, 4- 5 parts by mass of vinyl-1,3-dioxolan-2-one, 20 parts by mass of acrylic acid, 32 parts by mass of acrylamide, and 43 parts by mass of methacrylicamide were added, and the reaction was carried out at 70 ° C. for 18 hours. Then, it was cooled and adjusted to pH 7.0 using a 5 wt% sodium hydroxide aqueous solution. Then, the residual monomer was removed by steam distillation and concentrated under reduced pressure to obtain a composition for a storage device having a pH of 7.0 containing 10% by mass of the polymer (A1). The pH was adjusted by dropping a 5 wt% sodium hydroxide aqueous solution while measuring the pH at 25 ° C. using a pH meter (manufactured by HORIBA, Ltd.).

(2) Viscosity measurement With respect to the composition for a power storage device obtained above, water was added so that the polymer (A1) was 10% by mass, and a 5 wt% sodium hydroxide aqueous solution was added dropwise to bring the pH to 9.0. Adjusted to be. The viscosity of the composition for a power storage device thus obtained was measured at 25 ° C. using a B-type viscometer. The results are shown in Table 1 below.

(3) Measurement of Number Average Molecular Weight When the molecular weight of the composition for a power storage device obtained above was measured using GPC, the number average molecular weight was 150,000. The measurement conditions were as follows.
(Measurement condition)
-Measuring equipment: GPC (model number: HLC-8220) manufactured by Tosoh Corporation
-Column: TSKgel guardcolum PW _XL (manufactured by Tosoh Co., Ltd.), TSK-GEL G2500PW _XL (manufactured by Tosoh Co., Ltd.), TSK-GEL GMPW _XL (manufactured by Tosoh Co., Ltd.)
-Eluent: 0.1 M NaNO ₃ aqueous solution-Calibration curve: Standard polyethylene oxide-Measurement method: Dissolve the polymer (A) in the eluent so that the solid content is 0.3 wt%, and measure after filtering.

5.1.2. Preparation of slurry for power storage device electrode (1) Synthesis of silicon material (active material) A mixture of crushed silicon dioxide powder (average particle size 10 μm) and carbon powder (average particle size 35 μm) is heated at a temperature of 1100 ° C to 1600 ° C. _{Silicon oxide represented by the composition formula SiO x} (x = 0.5 to 1.1) after heat treatment for 10 hours under a nitrogen stream (0.5 NL / min) in an electric furnace adjusted to the range of Powder (average particle size 8 μm) was obtained. 300 g of this silicon oxide powder was charged into a batch type heating furnace, and the temperature was raised from room temperature (25 ° C.) to 1100 ° C. at a heating rate of 300 ° C./h while maintaining a reduced pressure of 100 Pa by a vacuum pump. .. Next, while maintaining the pressure in the heating furnace at 2000 Pa, heat treatment (graphite coating treatment) was performed at 1100 ° C. for 5 hours while introducing methane gas at a flow rate of 0.5 NL / min. After the graphite coating treatment was completed, the mixture was cooled to room temperature at a temperature lowering rate of 50 ° C./h to obtain about 330 g of graphite-coated silicon oxide powder. This graphite-coated silicon oxide is a conductive powder (active material) whose surface is coated with graphite, and its average particle size is 10.5 μm. The proportion of the graphite coating in the mass% was 2% by mass.

(2) Preparation of slurry for power storage device electrode 0.2 parts by mass (solid content conversion value) of polymer (A1) was added to a biaxial planetary mixer (manufactured by Primex Co., Ltd., trade name "TK Hibismix 2P-03"). , Add 10% by mass of the polymer (A1) obtained above as a composition for a storage device having a pH of 7.0), and 1.0 mass of a thickener (trade name "CMC2200", manufactured by Daicel Co., Ltd.). 77 parts by mass (solid content conversion value) of artificial graphite (manufactured by Showa Denko Materials Co., Ltd., trade name "MAG"), which is highly crystalline graphite as the negative electrode active material, of the graphite-coated silicon oxide obtained above. 19 parts by mass (solid content conversion value) of the powder and 1 part by mass of carbon (acetylene black manufactured by Denka Co., Ltd.) as a conductivity-imparting agent were added, and the mixture was stirred at 60 rpm for 1 hour to obtain a paste. 1.8 parts by mass (solid conversion value) of SBR (manufactured by JSR Corporation, trade name "TRD105A") and water were added to the obtained paste to adjust the solid content concentration to 48% by mass, and then stirring and defoaming. machine using the (Corporation Thinky Ltd., trade name "bubble tori Rentaro"), for 2 minutes at 200rpm, 5 minutes at 1,800rpm, in further under reduced pressure (about 2.5 × ¹⁰ 4 Pa) 1,800rpm A slurry (C / Si = 80/20) for a power storage device electrode containing 20% by mass of Si in the negative electrode active material was prepared by stirring and mixing for 1.5 minutes.

5.1.3. Manufacture and evaluation of power storage device (1) Manufacture of power storage device electrode (negative electrode) On the surface of a current collector made of copper foil with a thickness of 20 μm, the slurry for power storage device electrode (C / Si = 80/20) obtained above. Was uniformly applied by the doctor blade method so that the film thickness after drying was 60 μm, dried at 60 ° C. for 10 minutes, and then dried at 120 ° C. for 10 minutes. Then, a power storage device electrode (negative electrode) was obtained by pressing with a roll press so that the density of the active material layer was 1.6 g / cm ^3.

(2) Evaluation of Adhesion Strength of Negative Electrode Coating Layer Using a knife, make 10 cuts in each of the vertical and horizontal directions at 2 mm intervals from the active material layer to the depth reaching the current collector on the surface of the electrode sheet obtained above. I made a notch on the grid. An adhesive tape having a width of 18 mm (manufactured by Nichiban Co., Ltd., trade name "Cellotape" (registered trademark) specified in JIS Z1522) was attached to this notch and immediately peeled off, and the degree of shedding of the active material was visually evaluated. The evaluation criteria are as follows. The evaluation results are shown in Table 2 below.
(Evaluation criteria)
-5 points: No dropout of the active material layer.
・ 4 points: 1 to 5 pieces of active material layer are shed.
・ 3 points: 6 to 20 active material layers were dropped.
-2 points: 21 to 40 pieces of active material layer are shed.
-Point 1: The number of active material layers dropped is 41 or more.

(3) Manufacture of counter electrode (positive electrode) A biaxial planetary mixer (manufactured by Primex Co., Ltd., trade name "TK Hibismix 2P-03") and a binder for electrochemical device electrodes (manufactured by Kureha Corporation, product name "KF") Polymer # 1120 ”, hereinafter abbreviated as“ PVDF ”) 4.0 parts by mass (solid content conversion value), conductive aid (manufactured by Denka Co., Ltd., trade name“ Denka Black 50% Pressed Product ”) 3.0 parts by mass _{, 100 parts by mass (solid content conversion value) of LiCoO 2} (manufactured by Hayashi Kasei Co., Ltd.) and 36 parts by mass of N-methylpyrrolidone (NMP) having an average particle diameter of 5 μm were added as the positive electrode active material, and the mixture was stirred at 60 rpm for 2 hours. rice field. After adding NMP to the obtained paste and adjusting the solid content concentration to 65% by mass, a stirring defoaming machine (manufactured by Shinky Co., Ltd., trade name "Awatori Rentaro") was used at 200 rpm for 2 minutes. , 1,800 rpm for 5 minutes, and further under reduced pressure (about 2.5 × 10 ⁴ Pa) at 1,800 rpm for 1.5 minutes to prepare a slurry for a positive electrode. This positive electrode slurry was uniformly applied to the surface of the current collector made of aluminum foil by the doctor blade method so that the film thickness after removing the solvent was 150 μm, and heated at 120 ° C. for 20 minutes to remove the solvent. .. Then, a counter electrode (positive electrode) was obtained by press working with a roll press machine so that the density of the active material layer was 3.0 g / cm ^3.

(4) Assembly of Lithium Ion Battery Cell In a glove box Ar-substituted so that the dew point is -80 ° C or less, a Ni tab is welded to a glove box made by punching and molding the negative electrode manufactured above to 50 mm × 25 mm, and 56 mm. It was placed on a sheet made of polypropylene of × 32 mm. Next, a separator made of a polypropylene porous film punched to 55 mm × 30 mm (manufactured by Cellguard Co., Ltd., trade name “Cellguard # 2400”) was placed, and the positive electrode manufactured above was punched to 48 mm × 23 mm and then manufactured by Al. A welded tab was placed, and a polypropylene sheet of 56 mm × 32 mm was further placed. The structure is fixed by sticking 2 mm × 5 mm Kapton tape on the top and bottom of the long side portion of the structure, sandwiched between two 6 cm × 11 cm laminated films so as to be in the center, and three sides at 180 ° C. Was heat-sealed with a width of 1 cm. Then, after injecting 650 μL of the electrolytic solution, the remaining one side was vacuum-sealed to assemble a lithium ion battery cell (storage device). _{The electrolytic solution used here was prepared by dissolving LiPF 6} at a concentration of 1 mol / L in a solvent of ethylene carbonate / dimethyl carbonate = 3/7 (mass ratio), 2% by mass of fluoroethyl carbonate, and 1 by mass of vinyl carbonate. It is a solution in which mass% is dissolved.

(5) Evaluation of charge / discharge cycle characteristics (100 cycle capacity retention rate) The power storage device manufactured above was charged at a constant current (1.0 C) in a constant temperature bath adjusted to 25 ° C. When the voltage reached 4.2 V, charging was continued at a constant voltage (4.2 V), and when the current value reached 0.01 C, charging was completed (cutoff). After that, discharge is started at a constant current (1.0 C) in a constant temperature bath adjusted to 45 ° C., and when the voltage reaches 3.0 V, discharge is completed (cutoff), and discharge in the first cycle is performed. The capacity was calculated. In this way, charging and discharging were repeated 100 times. The capacity retention rate was calculated by the following formula and evaluated according to the following criteria. The evaluation results are shown in Table 2 below.
Capacity retention rate (%) = (Discharge capacity in the 100th cycle) / (Discharge capacity in the 1st cycle)
(Evaluation criteria)
・ 5 points: Capacity retention rate is 90% or more.
-4 points: Capacity retention rate is 88% or more and less than 90%.
-3 points: Capacity retention rate is 86% or more and less than 88%.
-2 points: Capacity retention rate is 84% or more and less than 86%.
-1 point: Capacity retention rate is 82% or more and less than 84%.
-0 points: Capacity retention rate is less than 82%.

In the measurement conditions, "1C" indicates a current value at which a cell having a certain electric capacity is discharged with a constant current and the discharge is completed in 1 hour. For example, "0.1C" is a current value at which the discharge is completed over 10 hours, and "10C" is a current value at which the discharge is completed over 0.1 hours.

(6) Evaluation of electrode plate expansion coefficient The film thickness of the negative electrode manufactured above was measured and used as the initial film thickness. Then, the power storage device manufactured above is charged at a constant current (0.2C) in a constant temperature bath regulated at 25 ° C., and when the voltage reaches 4.2V, the constant voltage (4) is continued. Charging was continued at .2V), and charging was completed (cutoff) when the current value reached 0.01C. After that, discharging is started at a constant current (0.2C) in a constant temperature bath adjusted to 25 ° C., and when the voltage reaches 2.5V, the discharge is completed (cutoff), and the chemical charging / discharging is completed. I let you. After that, a contact sensor (manufactured by KEYENCE, product name "GT2-H12KLF") was attached to the power storage device, and the film thickness at that time was taken as the film thickness after chemical conversion. Then, charging is started at a constant current (0.2C), and when the voltage reaches 4.2V, charging is continued at a constant voltage (4.2V), and when the current value reaches 0.01C. Was considered to be fully charged (cutoff). After that, discharging is started at a constant current (0.2C) in a constant temperature bath adjusted to 25 ° C., and when the voltage reaches 2.5V, the discharging is completed (cutoff), and at the time of discharging in the 10th cycle. By measuring the film thickness of, the electrode plate expansion coefficient was calculated by the following formula and evaluated according to the following criteria. The evaluation results are shown in Table 2 below.
Plate expansion coefficient (%) = ((film thickness at 10th cycle discharge)-(film thickness after chemical conversion) / (initial film thickness)) × 100
(Evaluation criteria)
・ 5 points: The coefficient of expansion of the electrode plate is 28% or less.
・ 4 points: The coefficient of expansion of the electrode plate is more than 28% to 30% or less.
・ 3 points: The coefficient of expansion of the electrode plate is more than 30% to 32% or less.
-2 points: The coefficient of expansion of the electrode plate is more than 32% to 34% or less.
・ 1 point: The coefficient of expansion of the electrode plate exceeds 34%.

5.2. Examples 4, 7-10, Comparative Examples 1, 4-6
In the above "5.1.1. Preparation and evaluation of composition for power storage device (1) Preparation of composition for power storage device", the types and amounts of each monomer are as shown in Table 1 below. A composition for each power storage device containing 10% by mass of the polymer was obtained in the same manner except for the above. Further, the viscosity and number average molecular weight of the composition for a power storage device thus obtained were measured in the same manner as in Example 1 above. In the present specification, the polymer (A) obtained in Example * is referred to as "polymer (A *)", and similarly, the polymer obtained in Comparative Example * is referred to as "polymer (B)". *) ”. That is, * corresponds to the number of the example or the comparative example.

Next, the slurry for the power storage device electrode was prepared in the same manner as in Example 1 above except that the polymer composition of the slurry for the power storage device electrode was changed as shown in Table 2 below, and the power storage device electrode and the power storage device were respectively prepared. Then, it was evaluated in the same manner as in Example 1 above.

5.3. Example 2
5.3.1. Synthesis of Acrylic Polymer 150 parts by mass of water and 0.2 parts by mass of sodium dodecylbenzenesulfonate were placed in a separable flask having a capacity of 7 liters, and the inside of the separable flask was sufficiently replaced with nitrogen. On the other hand, in another container, 60 parts by mass of water and an ether sulfate type emulsifier (trade name "Adecaria Soap SR1025", manufactured by ADEKA Co., Ltd.) as an emulsifier were added to 0.8 parts by mass in terms of solid content as a monomer. 20 parts by mass of butyl acrylate (BA), 22 parts by mass of cyclohexyl methacrylate (CHMA), 8 parts by mass of acrylonitrile (AN), 5 parts by mass of methyl methacrylate (MMA), 40 parts by mass of 2-ethylhexyl acrylate (EHA) and acrylic. 5 parts by mass of acid (AA) was added, and the mixture was sufficiently stirred to prepare a monomeric emulsion containing a mixture of the above monomers.

When the temperature inside the separable flask was started and the temperature inside reached 60 ° C., 0.5 part by mass of ammonium persulfate was added as a polymerization initiator. Then, when the temperature inside the separable flask reaches 70 ° C., the addition of the monomer emulsion prepared above is started, and the monomer is maintained while maintaining the temperature inside the separable flask at 70 ° C. The emulsion was added slowly over 3 hours. Then, the temperature inside the separable flask was raised to 85 ° C., and this temperature was maintained for 3 hours to carry out the polymerization reaction. After 3 hours, the separable flask was cooled to stop the reaction, and then ammonium water was added to adjust the pH to 7.6 to obtain an aqueous dispersion containing 30% by mass of particles made of an acrylic polymer. Obtained.

5.3.2. Preparation and evaluation of physical properties of composition for power storage device In the above "5.1.1. Preparation and evaluation of composition for power storage device (1) Preparation of composition for power storage device", the type and amount of each monomer are determined. A composition for a power storage device having a pH of 10.0 containing 10% by mass of the polymer (A2) was obtained in the same manner except as shown in Table 1 below. Further, the viscosity and number average molecular weight of the composition for a power storage device thus obtained were measured in the same manner as in Example 1 above.

5.3.3. Preparation of slurry for power storage device electrodes Next, a thickener (trade name "CMC2200", stock name "CMC2200", trade name, stock name " 1 part by mass (solid content conversion value, added as an aqueous solution with a concentration of 2% by mass) (manufactured by Daicel Co., Ltd.), 0.2 parts by mass (solid content conversion value, solid content conversion value, polymer (A2) obtained above) ) Is added as a composition for a power storage device containing 10% by mass of pH 10.0), and artificial graphite (manufactured by Showa Denko Materials Co., Ltd., trade name "MAG"), which is highly crystalline graphite as a negative electrode active material, is 77. Parts by mass (solid content conversion value), 19 parts by mass (solid content conversion value) of the graphite-coated silicon oxide powder obtained above, and 1 part by mass of carbon (made by Denka Co., Ltd., acetylene black) as a conductivity-imparting agent. It was charged and stirred at 60 rpm for 1 hour. Next, the acrylic polymer synthesized above was added as a post-addition component in an amount corresponding to 1.8 parts by mass (in terms of solid content), and the mixture was further stirred for 1 hour to obtain a paste. Water is added to the obtained paste to adjust the solid content concentration to 48% by mass, and then a stirring defoaming machine (manufactured by Shinky Co., Ltd., trade name "Awatori Rentaro") is used at 200 rpm for 2 minutes. , A storage device containing 20% by mass of Si in the negative electrode active material by stirring and mixing at 1,800 rpm for 5 minutes and further under reduced pressure (about 2.5 × 10 ^{4 Pa) at 1,800 rpm for 1.5 minutes.} An electrode slurry (C / Si = 80/20) was prepared.

5.3.4. Manufacture and Evaluation of Power Storage Device Electrodes and power storage devices were produced in the same manner as in Example 1 except that the slurry for power storage device electrodes prepared above was used, and evaluated in the same manner as in Example 1.

5.4. Example 5, Comparative Example 2
In the above "5.3.2.2 Preparation of composition for power storage device and measurement of viscosity", the polymer was prepared in the same manner except that the type and amount of each monomer were as shown in Table 1 below. A composition for each power storage device containing mass% was obtained. Further, the viscosity and number average molecular weight of the composition for a power storage device thus obtained were measured in the same manner as in Example 1 above.

Next, the slurry for the power storage device electrode was prepared in the same manner as in Example 2 above except that the polymer composition of the slurry for the power storage device electrode was changed as shown in Table 2 below, and the power storage device electrode and the power storage device were respectively prepared. Then, it was evaluated in the same manner as in Example 2 above.

5.5. Example 3
5.5.1. Synthesis of Fluorine-Containing Acrylic Polymer After sufficiently replacing the inside of an autoclave with an internal volume of about 6 L equipped with an electromagnetic stirrer with nitrogen, 2.5 L of deoxygenated pure water and 25 g of ammonium perfluorodecanoate as an emulsifier are charged. , The temperature was raised to 60 ° C. with stirring at 350 rpm. Next, a mixed gas composed of 70% vinylidene fluoride (VDF) and 30% propylene hexafluoride (HFP), which are monomers, was charged until the ^{internal pressure reached 20 kg / cm 2.} 25 g of a Freon 113 solution containing 20% of diisopropylperoxydicarbonate as a polymerization initiator was press-fitted using nitrogen gas to initiate polymerization. A mixed gas consisting of 60.2% VDF and 39.8% HFP was sequentially press-fitted so that the ^{internal pressure was maintained at 20 kg / cm 2} during the polymerization, and the pressure was ^{maintained at 20 kg / cm 2} . Further, since the polymerization rate decreases as the polymerization progresses, after 3 hours, the same amount of the same polymerization initiator solution as before was press-fitted using nitrogen gas, and the reaction was continued for another 3 hours. Then, the reaction solution was cooled and the stirring was stopped at the same time, and the reaction was stopped after releasing the unreacted monomer to obtain an aqueous dispersion containing 40% of the fine particles of the polymer F. As a result of analyzing the obtained polymer by ¹⁹ F-NMR, the mass composition ratio of each monomer was VDF / HFP = 21/4.

Next, after sufficiently replacing the inside of the separable flask having a capacity of 7 L with nitrogen, the aqueous dispersion containing the fine particles of the polymer F obtained above was added to the aqueous dispersion having 25 parts by mass in terms of polymer F in terms of polymer F, and the emulsifier "Adecaria Soap SR1025". (Product name, manufactured by ADEKA Co., Ltd.) 0.5 parts by mass, methyl methacrylate (MMA) 30 parts by mass, 2-ethylhexyl acrylate (EHA) 40 parts by mass, methacrylic acid (MAA) 5 parts by mass, and water 130. The parts by mass were sequentially charged and stirred at 70 ° C. for 3 hours to allow the polymer F to absorb the monomer. Next, 20 mL of a tetrahydrofuran solution containing 0.5 parts by mass of azobisisobutyronitrile as an oil-soluble polymerization initiator was added, the temperature was raised to 75 ° C., the reaction was carried out for 3 hours, and the reaction was further carried out at 85 ° C. for 2 hours. Was done. Then, after cooling, the reaction was stopped, and the pH was adjusted to 7.0 with a 2.5N aqueous sodium hydroxide solution to obtain a polymer composition containing 40% of a fluorine-containing acrylic polymer.

5.5.2. Preparation and evaluation of physical properties of composition for power storage device In the above "5.1.1. Preparation and evaluation of composition for power storage device (1) Preparation of composition for power storage device", the type and amount of each monomer are determined. A composition for a power storage device having a pH of 5.0 containing 10% by mass of the polymer (A3) was obtained in the same manner except as shown in Table 1 below. Further, the viscosity and number average molecular weight of the composition for a power storage device thus obtained were measured in the same manner as in Example 1 above.

5.5.3. Preparation of slurry for power storage device electrodes Next, a thickener (trade name "CMC2200", stock name "CMC2200", trade name, stock name " 1 part by mass (solid content conversion value, added as an aqueous solution with a concentration of 2% by mass) (manufactured by Daicel Co., Ltd.), 0.2 parts by mass (solid content conversion value, solid content conversion value, polymer (A3) obtained above) ) Is added as a composition for a power storage device having a pH of 5.0 containing 10% by mass), and artificial graphite (manufactured by Showa Denko Materials Co., Ltd., trade name "MAG"), which is highly crystalline graphite as a negative electrode active material, is 77. Parts by mass (solid content conversion value), 19 parts by mass (solid content conversion value) of the graphite-coated silicon oxide powder obtained above, and 1 part by mass of carbon (made by Denka Co., Ltd., acetylene black) as a conductivity-imparting agent. It was charged and stirred at 60 rpm for 1 hour. Next, the fluorine-containing acrylic polymer synthesized above was added as a post-addition component in an amount corresponding to 1.8 parts by mass (in terms of solid content), and the mixture was further stirred for 1 hour to obtain a paste. Water is added to the obtained paste to adjust the solid content concentration to 48% by mass, and then a stirring defoaming machine (manufactured by Shinky Co., Ltd., trade name "Awatori Rentaro") is used at 200 rpm for 2 minutes. , A storage device containing 20% by mass of Si in the negative electrode active material by stirring and mixing at 1,800 rpm for 5 minutes and further under reduced pressure (about 2.5 × 10 ^{4 Pa) at 1,800 rpm for 1.5 minutes.} An electrode slurry (C / Si = 80/20) was prepared.

5.5.4. Manufacture and Evaluation of Power Storage Device Electrodes and power storage devices were produced in the same manner as in Example 1 except that the slurry for power storage device electrodes prepared above was used, and evaluated in the same manner as in Example 1.

5.6. Example 6, Comparative Example 3
In the above "5.5.2.2 Preparation and evaluation of physical properties of composition for power storage device", the polymer components were similarly prepared in the same manner except that the types and amounts of each monomer were as shown in Table 1 below. A composition for each power storage device containing 10% by mass was obtained. Further, the viscosity of the composition for a power storage device thus obtained was measured in the same manner as in Example 1 above.

Next, the slurry for the power storage device electrode was prepared in the same manner as in Example 3 above except that the polymer composition of the slurry for the power storage device electrode was changed as shown in Table 2 below, and the power storage device electrode and the power storage device were respectively prepared. Then, it was evaluated in the same manner as in Example 3 above.

5.7. Evaluation Results Table 1 below shows the composition and physical property values of the polymers used in Examples 1 to 10 and Comparative Examples 1 to 5. Table 2 below shows the polymer composition and each evaluation result of the slurry for power storage device electrodes used in Examples 1 to 10 and Comparative Examples 1 to 6.

The abbreviations of the monomers in Tables 1 and 2 above represent the following compounds, respectively.
<Compound having a cyclic carbonate group>
-VDO: Compound represented by the following formula (9), 4-vinyl-1,3-dioxolane-2-one-M-1: Compound represented by the following formula (10)

<Unsaturated carboxylic acid>
-TA: Itaconic acid-AA: Acrylic acid-MAA: Methacrylic acid <(meth) acrylamide>
-AAM: Acrylamide-MAM: Methacrylamide-DAAM: N, N-dimethylacrylamide <Compound having a sulfo group>
-NASS: Sodium styrene sulfonate <Compound with hydroxyl group>
-HEA: 2-hydroxyethyl acrylate-HEMA: 2-hydroxyethyl methacrylate-VA: Vinyl alcohol <unsaturated carboxylic acid ester>
-MMA: Methyl methacrylate-CHMA: Cyclohexyl methacrylate-BA: n-butyl acrylate-EA: Ethyl acrylate-2EHA: 2-ethylhexyl acrylate <conjugated diene compound>
-BD: 1,3-butadiene <aromatic vinyl compound>
・ ST: Styrene <α, β-unsaturated nitrile compound>
・ AN: Acrylonitrile

As is clear from the above Tables 1 and 2, the slurry for the electricity storage device electrode prepared by using the composition for the electricity storage device according to the present invention shown in Examples 1 to 10 is the case of Comparative Examples 1 to 6. It was found that the active materials having a large volume change due to charging and discharging can be suitably bonded to each other, and the adhesion between the active material layer and the current collector can be maintained well. As a result, even if the active material repeatedly expands and contracts in volume by repeating charging and discharging, a power storage device electrode capable of effectively suppressing peeling of the active material layer and maintaining good charging and discharging characteristics was obtained. .. Further, it was found that the power storage device (lithium ion secondary battery) provided with these power storage device electrodes also has good charge / discharge rate characteristics. The reason for this is that the energy storage device electrodes according to Examples 1 to 10 shown in Table 1 have a film of an active material layer due to charge and discharge, as compared with the cases of Comparative Examples 1 to 6, based on the evaluation results of the electrode plate expansion coefficient. It is presumed that the change in thickness can be reduced and the conductive network inside the active material layer can be maintained. Furthermore, it was found that the power storage device (lithium ion secondary battery) provided with these power storage device electrodes also has a good capacity retention rate when the charge / discharge cycle is carried out. By coating the active material with a polymer having a cyclic carbonate group, a good film was formed on the surface of the active material by the decomposition of the cyclic carbonate group during charging, the decomposition of the electrolyte component was suppressed, and the electrolyte depletion was prevented. It is presumed to be due to this.

The present invention is not limited to the above embodiment, and various modifications are possible. The present invention includes substantially the same configurations as those described in the embodiments (eg, configurations with the same function, method and result, or configurations with the same purpose and effect). The present invention also includes a configuration in which a non-essential part of the configuration described in the above embodiment is replaced with another configuration. Further, the present invention also includes a configuration that exhibits the same effects as the configuration described in the above embodiment or a configuration that can achieve the same object. Further, the present invention also includes a configuration in which a known technique is added to the configuration described in the above embodiment.

Claims

Containing the polymer (A) and the liquid medium (B),
When the total of the repeating units contained in the polymer (A) is 100 parts by mass, the polymer (A) is:
The repeating unit (a1) derived from the compound having a cyclic carbonate group is 1 to 50 parts by mass.
A repeating unit derived from an unsaturated carboxylic acid (a2), a repeating unit derived from (meth) acrylamide (a3), a repeating unit derived from a compound having a sulfo group (a4), and a repeating unit derived from a compound having a hydroxyl group. At least one repeating unit selected from the group consisting of (a5) is 50 to 99 parts by mass.
A composition for a power storage device containing.
The composition for a power storage device according to claim 1, wherein the pH is 5 to 11.
The composition for a power storage device according to claim 1 or 2, wherein the 10% by mass aqueous solution of the polymer (A) has a viscosity at pH 9 of 200,000 to 200,000 mPa · s.
The composition for a power storage device according to any one of claims 1 to 3, wherein the liquid medium (B) is water.
The composition for a power storage device according to any one of claims 1 to 4.
At least one polymer (C) selected from the group consisting of a styrene-butadiene copolymer, an acrylic polymer, and a fluorine-based polymer, and
Slurry for power storage device electrodes.
The slurry for a power storage device electrode according to claim 5, which contains 5 to 100 parts by mass of the polymer (A) with respect to 100 parts by mass of the polymer (C).
The slurry for a power storage device electrode according to claim 5 or 6, further containing an active material.
The slurry for a power storage device electrode according to claim 7, which contains a silicon material as the active material.
The slurry for a power storage device electrode according to any one of claims 5 to 8, further containing a thickener.
A current collector comprising an active material layer formed by applying and drying the slurry for a power storage device electrode according to any one of claims 5 to 9 on the surface of the current collector. Device electrode.
A power storage device including the power storage device electrode according to claim 10.