JP2023114116A - Acylated, crosslinked, copolymerized aliphatic polycarbonate, polymer binder for all-solid-state battery and all-solid secondary battery - Google Patents

Abstract

To provide a novel polymer useful for a polymer binder for an all-solid-state battery, or the like.SOLUTION: An acylated, crosslinked, copolymerized aliphatic polycarbonate is a crosslinked, copolymerized aliphatic polycarbonate composed of an oxygen-containing heterocycle diol comprising an aliphatic polyol and a spiro structure. The acylated, crosslinked, copolymerized aliphatic polycarbonate is characterized by a structure with a polymeric molecular terminal capped with an acyl group. The ratio of acyl groups at the polymeric molecular terminals to hydrogen atoms is expressed as a polymeric average density (eq/T): (100:0)-(65:35).SELECTED DRAWING: Figure 3

Description

TECHNICAL FIELD The present invention relates to an acylated crosslinked copolymerized aliphatic polycarbonate, a polymer binder for an all-solid battery, and an all-solid secondary battery.

A lithium ion secondary battery uses a liquid electrolyte dissolved in a non-aqueous solvent as an electrolyte.

On the other hand, a solid-state secondary battery uses a solid material as an electrolyte. An all-solid secondary battery is manufactured from the solid electrolyte and other solid materials such as a positive electrode mixture and a negative electrode mixture, which are constituent elements of the battery. Therefore, the all-solid secondary battery uses a binder that binds the solid materials of the constituent elements of the battery.

Patent Document 1 discloses a method of manufacturing a positive electrode, a negative electrode, and a solid electrolyte layer by binding solid materials using a binder resin such as polyvinylpyrrolidone or butylene rubber as a binder.

Patent Document 2 discloses that a polyvinyl acetal resin is used as a binder.

In addition, in Patent Document 3, the present inventor disclosed a three-dimensionally crosslinked copolymerized polycarbonate as a resin binder for a binder. Specifically, a three-dimensional cross-linked copolymer having structural units derived from two types of aliphatic diols, structural units derived from a polyol having 3 or more hydroxyl groups, and structural units derived from a diol having an ether bond. Discloses polycarbonate. This resin binder has improved binding properties with solid materials such as inorganic solid electrolytes and aluminum, and is excellent in formability and ionic conductivity. can improve.

JP 2014-137869 A JP 2014-212022 A WO2020/203881

However, all-solid-state secondary batteries are required to further improve their performance, and the binders used for them are also required to have better properties, such as adhesiveness, and are useful for such applications. , new polymers are desired.

An object of the present invention is to provide a novel polymer that is useful as a polymer binder for all-solid-state batteries.

As a result of investigations to solve the above problems, the present inventors found that when the hydroxyl groups at the ends of a crosslinked copolymerized aliphatic polycarbonate containing specific structural units are acylated at a specific ratio, bonding with an aluminum foil can be achieved. The inventors of the present invention have completed the present invention based on the finding that the ionic conductivity inside the battery can be improved by improving the adhesiveness and reducing the amount used.

（式（１）中、Ｒ^１は炭素数２以上２０以下の脂肪族炭化水素残基を表し、ｘは３以上１００以下の整数を表す。）

（式（２）中、Ｒ^２は、下記式（２－１）

を表し、Ｒ^２’およびＲ^２’’は、それぞれ独立して炭素数０以上５以下の脂肪族炭化水素残基を表し、Ｒ^２’’’は、水素原子または炭素数１以上５以下の脂肪族炭化水素残基を表す。）

（式（３）中、Ｒ^３は、スピロ構造を有し、構造中にヘテロ原子が含まれていても良い脂肪族炭化水素残基を表す。）

（式（４）中、Ｒ^４は炭素数２以上１０以下の脂肪族炭化水素残基を表し、ｍは１以上３０以下の整数を表す。）
ポリマー分子末端は、前記式（１）～（４）における左端部分のカーボネート酸素原子に結合する末端基がそれぞれ下記式（５－１）～（５－４）で表される構造のいずれかであり、前記式（１）～（４）における右端部分のＲ^１～Ｒ^４に結合する末端基が下記式（６）で表される構造であり、

（式（５－１）～（５－４）および式（６）中、Ｒ^５は、それぞれ独立して水素原子又はアシル基を表す。）
前記式（５－１）～（５－４）および式（６）で表される前記ポリマー分子末端のアシル基と水素原子との割合が、ポリマー平均の濃度（ｅｑ／Ｔ）で（１００：０）～（６５：３５）である。 The acylated crosslinked copolymer aliphatic polycarbonate according to the first aspect of the present invention comprises structural units represented by the following formulas (1) to (4),

(In formula (1), R ¹ represents an aliphatic hydrocarbon residue having 2 to 20 carbon atoms, and x represents an integer of 3 to 100.)

(In formula (2), R ² is the following formula (2-1)

, R ^2′ and R ^2″ each independently represent an aliphatic hydrocarbon residue having 0 to 5 carbon atoms, and R ^2′″ is a hydrogen atom or a C 1 to 5 Represents an aliphatic hydrocarbon residue. )

(In formula (3), R ³ represents an aliphatic hydrocarbon residue that has a spiro structure and may contain a heteroatom in the structure.)

(In formula (4), ^R4 represents an aliphatic hydrocarbon residue having 2 to 10 carbon atoms, and m represents an integer of 1 to 30.)
The terminal of the polymer molecule has any structure in which the terminal group bonded to the carbonate oxygen atom on the left end of the formulas (1) to (4) is represented by the following formulas (5-1) to (5-4), respectively. and the terminal group bonded to R ¹ to R ⁴ on the right end of the formulas (1) to (4) has a structure represented by the following formula (6),

(In formulas (5-1) to (5-4) and formula (6), each R ⁵ independently represents a hydrogen atom or an acyl group.)
The ratio of acyl groups and hydrogen atoms at the ends of the polymer molecules represented by formulas (5-1) to (5-4) and formula (6) is (100: 0) to (65:35).

The acyl group represented by ^R5 is preferably an acetyl group or a benzoyl group.

The R ¹ represents an aliphatic hydrocarbon residue having 8 to 12 carbon atoms, x represents an integer of 60 to 90,
R ² represents an aliphatic hydrocarbon residue in which R ^2″ in the formula (2-1) has 1 or more and 2 or less carbon atoms,
R ³ has 1 to 2 spiro atoms, and the heteroatom is an oxygen atom or a sulfur atom;
Preferably, R ⁴ represents an aliphatic hydrocarbon residue having 2 or more and 4 or less carbon atoms, and m represents an integer of 1 or more and 3 or less.

R ¹ is an alkylene group having 10 carbon atoms, R ² is an alkylene group having 1 carbon atoms, and R ^2″ in the formula (2-1) is an alkylene group having 1 carbon atoms, and R ³ is 2,2′-( 2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diyl)dipropanediyl group, wherein R ⁴ is an alkylene group having 2 carbon atoms and m is an integer of 3; It is preferable that there is.

The ratio of the structural units represented by the above formulas (1) to (4) is (1):(2):(3):(4) = 40 to 50:0.4 to 0.8 in terms of molar ratio. : 10-50: 10-35.

A polymer binder for an all-solid-state battery according to a second aspect of the present invention includes the acylated crosslinked copolymerized aliphatic polycarbonate and a lithium salt.

Preferably, said lithium salt comprises LiTFSI.

An all-solid secondary battery according to a third aspect of the present invention includes the acylated crosslinked copolymerized aliphatic polycarbonate.

An all-solid secondary battery according to a fourth aspect of the present invention includes the polymer binder for an all-solid battery.

The acylated crosslinked copolymerized aliphatic polycarbonate of the present invention provides a novel polymer that is useful as a polymer binder for all-solid-state batteries.

.
¹ H-NMR spectrum of the crosslinked copolymerized aliphatic polycarbonate according to Production Example 1. FIG. ¹³ C-NMR spectrum of the crosslinked copolymerized aliphatic polycarbonate according to Production Example 1. FIG. ¹ H-NMR spectrum of the acylated crosslinked copolymer aliphatic polycarbonate according to Example 1. FIG. ¹³ C-NMR spectrum of the acylated crosslinked copolymer aliphatic polycarbonate according to Example 1. FIG.

（式（１）中、Ｒ^１は炭素数２以上２０以下の脂肪族炭化水素残基を表し、ｘは３以上１００以下の整数を表す。）

（式（２）中、Ｒ^２は、下記式（２－１）

を表し、Ｒ^２’およびＲ^２’’は、それぞれ独立して炭素数０以上５以下の脂肪族炭化水素残基を表し、Ｒ^２’’’は、水素原子または炭素数１以上５以下の脂肪族炭化水素残基を表す。）

（式（３）中、Ｒ^３は、スピロ構造を有し、構造中にヘテロ原子が含まれていても良い脂肪族炭化水素残基を表す。）

（式（４）中、Ｒ^４は炭素数２以上１０以下の脂肪族炭化水素残基を表し、ｍは１以上３０以下の整数を表す。）
ポリマー分子末端は、前記式（１）～（４）における左端部分のカーボネート酸素原子に結合する末端基がそれぞれ下記式（５－１）～（５－４）で表される構造のいずれかであり、前記式（１）～（４）における右端部分のＲ^１～Ｒ^４に結合する末端基が下記式（６）で表される構造であり、

（式（５－１）～（５－４）および式（６）中、Ｒ^５は、それぞれ独立して水素原子又はアシル基を表す。）
前記式（５－１）～（５－４）および式（６）で表される前記ポリマー分子末端のアシル基と水素原子との割合が、ポリマー平均の濃度（ｅｑ／Ｔ）で（１００：０）～（６５：３５）である。 The acylated crosslinked copolymer aliphatic polycarbonate of the present invention comprises structural units represented by the following formulas (1) to (4),

(In formula (1), R ¹ represents an aliphatic hydrocarbon residue having 2 to 20 carbon atoms, and x represents an integer of 3 to 100.)

(In formula (2), R ² is the following formula (2-1)

, R ^2′ and R ^2″ each independently represent an aliphatic hydrocarbon residue having 0 to 5 carbon atoms, and R ^2′″ is a hydrogen atom or a C 1 to 5 Represents an aliphatic hydrocarbon residue. )

(In formula (3), R ³ represents an aliphatic hydrocarbon residue that has a spiro structure and may contain a heteroatom in the structure.)

(In formula (4), ^R4 represents an aliphatic hydrocarbon residue having 2 to 10 carbon atoms, and m represents an integer of 1 to 30.)
The terminal of the polymer molecule has any structure in which the terminal group bonded to the carbonate oxygen atom on the left end of the formulas (1) to (4) is represented by the following formulas (5-1) to (5-4), respectively. and the terminal group bonded to R ¹ to R ⁴ on the right end of the formulas (1) to (4) has a structure represented by the following formula (6),

(In formulas (5-1) to (5-4) and formula (6), each R ⁵ independently represents a hydrogen atom or an acyl group.)
The ratio of acyl groups and hydrogen atoms at the ends of the polymer molecules represented by formulas (5-1) to (5-4) and formula (6) is (100: 0) to (65:35).

The acylated crosslinked copolymerized aliphatic polycarbonate of the present invention is, for example, combined with a lithium salt to form a polymer binder for an all-solid battery, as described later, and made into a slurry using a hydrophobic solvent to prepare a positive electrode mixture and a negative electrode. It can be used in manufacturing an all-solid secondary battery by permeating between the mixture and the solid electrolyte.

で表される構造単位において、Ｒ^１は炭素数２以上２０以下の脂肪族炭化水素残基を表し、ｘは３以上１００以下の整数を表す。 (Structural Unit Represented by Formula (1))
Formula (1) according to the present invention

In the structural unit represented by R ¹ represents an aliphatic hydrocarbon residue having 2 or more and 20 or less carbon atoms, and x represents an integer of 3 or more and 100 or less.

If the number of carbon atoms in R ¹ in formula (1) is less than 2, the dispersibility of the acylated crosslinked copolymerized aliphatic polycarbonate in the slurry used in the production of the all-solid secondary battery described later tends to decrease. . As will be described later, the polymer binder according to the present invention desirably permeates between the positive electrode mixture, the negative electrode mixture, and the solid electrolyte during the manufacturing process of the all-solid secondary battery. Therefore, since a slurry using a hydrophobic solvent is usually used in the manufacturing process, it is desirable to disperse the acylated crosslinked copolymerized aliphatic polycarbonate contained in the polymer binder of the present invention in a hydrophobic solvent.

On the other hand, when the number of carbon atoms in R ¹ exceeds 20, the affinity with lithium ions tends to decrease.

R ¹ may be a single species or a combination of multiple species, but it is preferable that R ¹ is a single species.

When R ¹ is a single type, R ¹ is preferably an aliphatic hydrocarbon residue having 8 to 12 carbon atoms, more preferably an alkylene group having 9 to 11 carbon atoms, and 10 carbon atoms. Particular preference is given to aliphatic hydrocarbon residues.

When R ¹ has a plurality of types, R ¹ preferably represents an alkylene group having 2 to 7 carbon atoms and an aliphatic hydrocarbon residue having 2 to 20 carbon atoms. When there are multiple types of R ¹ , the arrangement of the structural units is not particularly limited. It may be a graft copolymer.

When the number of carbon atoms in R ¹ is within this range, the polymer binder for all-solid-state battery using the acylated crosslinked copolyaliphatic polycarbonate has an excellent balance of binding properties, moldability and ionic conductivity.

The aliphatic hydrocarbon residue for R ¹ may be linear, branched or cyclic, but is preferably linear. In addition, the aliphatic hydrocarbon residue for R ¹ may be substituted with an alkoxy group, a cyano group, a primary to tertiary amino group, a halogen atom, etc. in the main chain or side chain, but is unsubstituted. and preferred.

Examples of aliphatic hydrocarbon residues having 2 to 20 carbon atoms include ethane-1,2-diyl group, propane-1,3-diyl group, butane-1,4-diyl group, pentane-1, 5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group, decane-1,10-diyl group, Chain aliphatics such as dodecane-1,12-diyl group, tetradecane-1,14-diyl group, hexadecane-1,16-diyl group, octadecane-1,18-diyl group and icosane-1,20-diyl group hydrocarbon group, 1-methylethane-1,2-diyl group, 2-methylpropane-1,3-diyl group, 2-methylbutane-1,4-diyl group, 2-ethylbutane-1,4-diyl group, 3 branched aliphatic hydrocarbon groups such as -methylpentane-1,5-diyl group, 2-methylhexane-1,6-diyl group, 5-methyldecane-1,10-diyl group, cyclopropane-1,2- diyl group, cyclobutane-1,2-diyl group, cyclobutane-1,3-diyl group, cyclopentane-1,2-diyl group, cyclopentane-1,3-diyl group, cyclohexane-1,1-diyl group, cyclohexane-1,2-diyl group, cyclohexane-1,3-diyl group, cyclohexane-1,4-diyl group, cycloheptane-1,2-diyl group, cycloheptane-1,3-diyl group, cycloheptane- 1,4-diyl group, cyclooctane-1,2-diyl group, cyclooctane-1,3-diyl group, cyclooctane-1,4-diyl group, cyclooctane-1,5-diyl group, cyclononane-1 ,2-diyl group, cyclononane-1,3-diyl group, cyclononane-1,4-diyl group, cyclononane-1,5-diyl group, cyclodecane-1,2-diyl group, cyclodecane-1,3-diyl group , cyclodecane-1,4-diyl group, cyclodecane-1,5-diyl group and cyclodecane-1,6-diyl group. Among these aliphatic hydrocarbon residues, linear aliphatic hydrocarbon groups are preferred, alkylene groups having 10 carbon atoms are more preferred, and decane-1,10-diyl groups are particularly preferred.

x in formula (1) represents the number of repeating units shown in parentheses in formula (1) and represents an integer of 3 or more and 100 or less. If x is less than 3, the dispersibility of the solid electrolyte, positive electrode active material, negative electrode active material, etc. in the slurry during production of the all-solid secondary battery is reduced. On the other hand, if x exceeds 100, the slurry will have a high viscosity when it is prepared, and the coating properties of the slurry will deteriorate.

x is preferably 30 or more and 95 or less, more preferably 60 or more and 90 or less, and particularly preferably 70 or more and 80 or less.

A polymer binder for an all-solid-state battery using the acylated cross-linked copolyaliphatic polycarbonate of the present invention makes it possible to form a positive electrode, a solid electrolyte layer, or a negative electrode that constitutes an all-solid secondary battery in a sheet form. Therefore, it is desirable that the adhesive has excellent binding properties with the electrode mixture or the inorganic solid electrolyte and that it has excellent strength. When x is large, the strength tends to improve.

で表される構造単位を含む、アシル化架橋型共重合脂肪族ポリカーボネートは、公知のエステル交換反応およびアシル化反応を行って得ることができる。例えば、Ｒ^１で表される脂肪族炭化水素残基の末端に水酸基が結合しているジオール化合物にジフェニルカーボネート又はホスゲン等を反応させてカーボネート化して、予めポリマー分子末端が水酸基であるオリゴマーを調製し、そのオリゴマーと、他のジオール化合物等と共重合する方法により架橋型共重合脂肪族ポリカーボネートを得、そのポリマー分子末端の水酸基の一部を、公知のアシル化反応でアシル化して、アシル化架橋型共重合脂肪族ポリカーボネートを得ることができる。 formula (1)

An acylated crosslinked copolymer aliphatic polycarbonate containing a structural unit represented by can be obtained by known transesterification and acylation reactions. For example, a diol compound in which a hydroxyl group is bonded to the end of an aliphatic hydrocarbon residue represented by ^R1 is reacted with diphenyl carbonate or phosgene to form a carbonate, thereby preparing an oligomer having a hydroxyl group at the end of the polymer molecule. Then, a crosslinked copolymerized aliphatic polycarbonate is obtained by copolymerizing the oligomer with another diol compound or the like, and some of the hydroxyl groups at the ends of the polymer molecules are acylated by a known acylation reaction to acylate. A crosslinked copolymerized aliphatic polycarbonate can be obtained.

Examples of the diol compound in which a hydroxyl group is bonded to the terminal of the aliphatic hydrocarbon residue represented by R ¹ include 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol, 1,5 -pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol, 1,14- tetradecanediol, 1,16-hexadecanediol, 1,18-octadecanediol, 1,20-icosanediol and the like.

In the acylated crosslinked copolymerized aliphatic polycarbonate of the present invention, the ratio of the structural unit of formula (1) to the sum of the structural units of formulas (1) to (4) is not particularly limited, but the parentheses in formula (1) The ratio of the repeating units within is preferably 20 mol% to 70 mol%, more preferably 30 mol% to 60 mol%, even more preferably 40 mol% to 50 mol%, and particularly preferably 45 mol% to 50 mol%. . In addition, the ratio of formula (1) is not a ratio based on the entire formula (1), but a value based on the repeating unit in parentheses in the formula (1). Unless otherwise specified, the ratio of the structural unit of each formula to the sum of the structural units of formulas (1) to (4) is based on the repeating unit in parentheses in formula (1).

で表される構造単位において、Ｒ^２は、下記式（２－１）

を表し、Ｒ^２’およびＲ^２’’は、それぞれ独立して炭素数０以上５以下の脂肪族炭化水素残基を表し、Ｒ^２’’’は、水素原子または炭素数１以上５以下の脂肪族炭化水素残基を表す。 (Structural unit represented by formula (2))
Formula (2) according to the present invention

In the structural unit represented by R ² is the following formula (2-1)

, R ^2′ and R ^2″ each independently represent an aliphatic hydrocarbon residue having 0 to 5 carbon atoms, and R ^2′″ is a hydrogen atom or a C 1 to 5 Represents an aliphatic hydrocarbon residue.

In formula (2-1), the case where R ^2′ and R ^2″ have 0 carbon atoms means that only a bond exists, and the central carbon atom in the parentheses and other It means a bond with a carbonate oxygen atom or the like in the structure. In addition, the bond represented by a straight line connecting outside the parentheses in the vertical direction in formula (2-1) is the same as the bond represented by a straight line connecting outside the right end parenthesis in the horizontal direction in formula (2-1). , means a bond with a carbonate oxygen atom of another structure.

The aliphatic hydrocarbon residue for R2 ^' and R2 ^'' may be linear, branched or cyclic, but is preferably linear. In addition, the aliphatic hydrocarbon residue for R ^{2 '} and R ^{2 ''} may be substituted with an alkoxy group, a cyano group, a primary to tertiary amino group, a halogen atom, etc. on the main chain or side chain. is preferably unsubstituted.

Aliphatic hydrocarbon residues having 0 to 5 carbon atoms for R ^2′ and R ^2″ include, for example, methane-diyl group, ethane-1,2-diyl group, propane-1,3-diyl butane-1,4-diyl group, chain aliphatic hydrocarbon group such as pentane-1,5-diyl group, 1-methylethane-1,2-diyl group, 2-methylpropane-1,3-diyl 2-methylbutane-1,4-diyl group, branched aliphatic hydrocarbon group such as 2-ethylbutane-1,4-diyl group, cyclopropane-1,2-diyl group, cyclobutane-1,2-diyl cyclobutane-1,3-diyl group, cyclopentane-1,2-diyl group and cyclopentane-1,3-diyl group. In the present specification, the aliphatic hydrocarbon residue having 0 carbon atoms in R ^{2 '} and R ^{2 ''} means a bond between the central carbon atom and a carbonate oxygen atom of another structure, etc., as described above. . Among these aliphatic hydrogen residues, linear aliphatic hydrocarbon groups are preferred. Further, an aliphatic hydrocarbon residue having 1 to 2 carbon atoms is preferred, and a methane-diyl group (methylene group) is more preferred.

The aliphatic hydrocarbon residue for R ^2′″ may be linear, branched or cyclic, but is preferably linear. In addition, the aliphatic hydrocarbon residue for R ^2''' may be substituted with an alkoxy group, a cyano group, a primary to tertiary amino group, a halogen atom or the like in the main chain or side chain. Substitution is preferred.

Examples of aliphatic hydrocarbon residues having 1 to 5 carbon atoms for R ^2''' include chain aliphatic hydrocarbon groups such as methyl, ethyl, propyl, butyl, and pentyl groups, Branched aliphatic hydrocarbon groups such as 2-methylethyl group (isopropyl group), 2-methylpropyl group, 2,2-dimethylethyl group (t-butyl group), 2-methylbutyl group, cyclopropyl group, cyclobutyl group , and cyclopentyl groups.

The structural unit represented by formula (2) functions as a crosslinked structure that three-dimensionally crosslinks other structural units. As a result, the crosslinked structure becomes uniform, and the dispersibility of the polymer binder for an all-solid-state battery in a hydrophobic solvent is improved.

An acylated crosslinked copolymer aliphatic polycarbonate containing a structural unit represented by formula (2) can be obtained by known transesterification and acylation reactions. For example, an oligomer having a structural unit represented by formula (1) in which both molecular ends are hydroxyl groups, a diol compound having a structure represented by inner brackets in formula (3), and an inner A diol compound having a structure represented by parentheses, and a triol compound or tetraol in which hydroxyl groups are bonded to the ends of the hydrocarbon residues represented by R ^2′ and R ^2″ in formula (2-1) and a compound are carbonate-bonded with diphenyl carbonate or the like to obtain a crosslinked copolymerized aliphatic polycarbonate, part of the hydroxyl groups at the ends of the polymer molecule are acylated by a known acylation reaction to obtain an acylated crosslinked copolymer. A polymerized aliphatic polycarbonate can be obtained.

Examples of triol compounds or tetraol compounds in which hydroxyl groups are bonded to the ends of hydrocarbon residues represented by R ^2′ and R ^2″ in formula (2-1) include glycerin, trimethylolpropane, and pentaerythritol. etc. These triol compounds or tetraol compounds may be used alone or in combination of two or more. In the present invention, it is preferred to use pentaerythritol.

As another method for producing an acylated crosslinked copolymer aliphatic polycarbonate containing a structural unit represented by formula (2), a compound having 3 or 4 carboxy groups is used instead of the above-mentioned triol compound or tetraol compound. can also be used.

Examples of compounds having 3 or more carboxy groups include 1,3,5-pentanetricarboxylic acid and 1,2,3,4-butanetetracarboxylic acid.

In the acylated crosslinked copolymerized aliphatic polycarbonate of the present invention, the ratio of the structural unit of formula (2) to the total sum of structural units of formulas (1) to (4) is not particularly limited, but is 0.01 mol% to 10 mol%. It is preferably 0.05 mol% to 5 mol%, more preferably 0.1 mol% to 1 mol%, particularly preferably 0.4 mol% to 0.8 mol%, and 0.4 mol%. ~0.6 mol% is most preferred. Here, with respect to formula (1), the ratio is a value based on the repeating unit in parentheses in formula (1), not the entire formula (1).

When the ratio of the structural unit of the formula (2) is lowered to lower the crosslink density, the adhesiveness of the polymer binder in which the metal salt is dissolved tends to be lowered. On the other hand, if the proportion of the structural unit of formula (2) is too large, the crosslink density will increase and gelation will tend to occur, resulting in reduced dispersibility in hydrophobic solvents.

で表される構造単位において、Ｒ^３は、スピロ構造を有し、構造中にヘテロ原子が含まれていても良い脂肪族炭化水素残基を表す。 (Structural unit represented by formula (3))
Formula (3) according to the present invention

In the structural unit represented by R ³ represents an aliphatic hydrocarbon residue which has a spiro structure and may contain a heteroatom in the structure.

Examples of the heteroatom include an oxygen atom, a sulfur atom, a nitrogen atom, etc. The heteroatom is preferably an oxygen atom or a sulfur atom, and more preferably an oxygen atom.

It is believed that the structure represented by formula (3) contributes to dispersibility in the hydrophobic solvent used in the production of all-solid-state batteries. Since the acylated crosslinked copolymerized aliphatic polycarbonate of the present invention has this structure, the affinity of the polymer binder using the acylated crosslinked copolymerized aliphatic polycarbonate of the present invention to a hydrophobic solvent is improved, In addition, the cohesive force in the hydrophobic solvent is lowered, and as a result, the dispersibility in the hydrophobic solvent is improved, which is preferable.

The hydrocarbon residue having a spiro structure represented by R ³ in formula (3) is a hydrocarbon residue having a bicyclic spiro structure having one spiro atom, or two or more spiro structures. Although it may be three or more rings having atoms, it is preferably a hydrocarbon residue having a bicyclic or tricyclic spiro structure with 1 to 2 spiro atoms, and has one spiro atom A hydrocarbon residue having a bicyclic spiro structure is preferred. The number of atoms forming the ring is preferably 4 or more, more preferably 6 or more. Further, it is more preferable that some of the carbon atoms forming the ring are substituted with heteroatoms such as oxygen atoms.

When R ³ in formula (3) is a hydrocarbon residue having a spiro structure, the bulkiness increases, the dispersibility in the slurry used for making the all-solid-state battery increases, and the ring-forming carbon It is more preferred that some of the atoms are replaced with heteroatoms, since this increases the affinity with the lithium salt.

Hydrocarbon residues having a bicyclic or higher spiro structure include, for example, a spiro[2.2]pentane-1,4-diyl group, a spiro[3.3]heptane-2,6-diyl group, a spiro[ 4.4]nonane-2,7-diyl group, spiro[5.5]undecane-3,9-diyl group, spiro[3.5]nonane-2,7-diyl group, spiro[2.6]nonane -1,6-diyl group, spiro[4.5]decane-1,5-diyl group, dispiro[4.2.4.2]tetradecane-1,11-diyl group, dispiro[4.1.5. 2] tetradecane-2,12-diyl group, 1,1′-spirobi[indene]-8,8′-diyl group, 1H,1′H-2,2′-spirobi[naphthalene]-9,9′- A diyl group is mentioned.

Hydrocarbon residues having a spiro structure in which some of the atoms forming the ring are substituted with heteroatoms such as oxygen atoms include, for example, 2,2′-(2,4,8,10,-tetraoxa Spiro[5.5]undecane-3,9-diyl)dipropanediyl group (common monomer name: spiroglycol), 2,2′,3,3′-tetrahydro-1,1′-spirobi[indene]-7 ,7'-diyl group, 4,8-dihydro-1H,1'H-2,4'-spirobi[quinoline]-6',7-diyl group, 4,4,4',4'-tetramethyl- A 2,2'-spirobi[chroman]-7,7'-diyl group can be mentioned. Among these, a 2,2'-(2,4,8,10,-tetraoxaspiro[5.5]undecane-3,9-diyl)dipropanediyl group is preferred.

A hydrocarbon residue having a spiro structure may be saturated or unsaturated, and the main chain or side chain is substituted with an alkoxy group, a cyano group, a primary to tertiary amino group, a halogen atom, or the like. may be

Structural units represented by formula (3) can be present in blocks or randomly in the acylated crosslinked copolyaliphatic polycarbonate.

Here, when the structural unit represented by the formula (3) is present as a block in the main chain, the structural units represented by the formula (3) are linked to form a block by 1 or more and 10 or less. It is more preferable that 1 or more and 5 or less are connected, and it is particularly preferable that 1 or more and 3 or less are connected. If the number of links is 3 or less, the dispersibility of the polymer binder in a hydrophobic solvent is improved.

An acylated crosslinked copolymer aliphatic polycarbonate containing a structural unit represented by formula (3) can be obtained by a known transesterification reaction. For example, an oligomer having a structural unit represented by formula (1) in which both molecular ends are hydroxyl groups, and the ends of hydrocarbon residues represented by R ^2′ and R ^2″ in formula (2-1) a triol compound or tetraol compound having a hydroxyl group bonded to the diol compound having the structure represented by the inner brackets in formula (4), and the diol having the structure represented by the inner brackets in formula (3) and a compound are carbonate-bonded with diphenyl carbonate or the like to obtain a crosslinked copolymerized aliphatic polycarbonate, part of the hydroxyl groups at the ends of the polymer molecule are acylated by a known acylation reaction to obtain an acylated crosslinked copolymer. A polymerized aliphatic polycarbonate can be obtained.

Examples of the diol compound having the structure represented by the inner brackets in formula (3) include spiro[2.2]pentane-1,4-diol, spiro[3.3]heptane-2,6-diyl group, spiro [4.4]nonane-2,7-diol, spiro[5.5]undecane-3,9-diol, spiro[3.5]nonane-2,7-diol, spiro[2.6]nonane-1 ,6-diol, spiro[4.5]decane-1,5-diol, dispiro[4.2.4.2]tetradecane-1,11-diol, dispiro[4.1.5.2]tetradecane-2 , 12-diol, 1,1′-spirobi[indene]-8,8′-diol, 1H,1′H-2,2′-spirobi[naphthalene]-9,9′-diol, 2,2′- (2,4,8,10,-tetraoxaspiro[5.5]undecane-3,9-diyl)dipropanediol (alias: spiroglycol), 2,2′,3,3′-tetrahydro-1, 1'-spirobi[indene]-7,7'-diyl group, 4,8-dihydro-1H,1'H-2,4'-spirobi[quinoline]-6',7-diol, 4,4,4 and ',4'-tetramethyl-2,2'-spirobi[chroman]-7,7'-diol. Among these, spiroglycols are preferred.

In the acylated crosslinked copolymerized aliphatic polycarbonate of the present invention, the ratio of the structural unit of formula (3) to the total sum of structural units of formulas (1) to (4) is not particularly limited, but is 5 mol% to 55 mol%. , more preferably 10 mol % to 50 mol %, still more preferably 20 mol % to 35 mol %, and particularly preferably 25 mol % to 33 mol %. Here, with respect to formula (1), the ratio is a value based on the repeating unit in parentheses in formula (1), not the entire formula (1).

で表される構造単位において、Ｒ^４は炭素数２以上１０以下の脂肪族炭化水素残基を表し、ｍは１以上３０以下の整数を表す。 (Structural unit represented by formula (4))
Formula (4) according to the present invention

In the structural unit represented by , R ⁴ represents an aliphatic hydrocarbon residue having 2 to 10 carbon atoms, and m represents an integer of 1 to 30.

It is believed that the structural unit represented by formula (4) contributes to the adhesion of the polymer binder to the positive/negative electrode active materials, the solid electrolyte, and the current collector, which are the binding target materials in the all-solid-state battery. . Having this structure in the acylated crosslinked copolymerized aliphatic polycarbonate polymer of the present invention is preferable because the flexibility and polarity of the polymer binder are increased, and as a result, the adhesiveness to the binding target substance is improved.

R ⁴ in formula (4) is not particularly limited as long as it is an aliphatic hydrocarbon residue having 2 to 10 carbon atoms, but is preferably an alkylene group having 2 to 4 carbon atoms. When the number of carbon atoms is 2 or more, the flexibility of the polymer tends to be improved.

m in formula (4) is not particularly limited as long as it is an integer of 1 or more and 30 or less, preferably an integer of 1 or more and 20 or less, more preferably an integer of 2 or more and 10 or less, and an integer of 3 or more and 5 or less It is more preferably an integer, particularly preferably an integer of 1 or more and 3 or less, and most preferably 3. When m is 1 or more, the flexibility of the acylated crosslinked copolymer aliphatic polycarbonate tends to increase, and when it is 5 or less, the adhesion to metal tends to improve.

Examples of aliphatic hydrocarbon residues having 2 to 10 carbon atoms for R ⁴ in formula (4) include ethane-1,2-diyl group, propane-1,3-diyl group, butane-1 ,4-diyl group, pentane-1,5-diyl group, hexane-1,6-diyl group, heptane-1,7-diyl group, octane-1,8-diyl group, nonane-1,9-diyl group , chain aliphatic hydrocarbon groups such as decane-1,10-diyl group, 1-methylethane-1,2-diyl group, 2-methylpropane-1,3-diyl group, 2-methylbutane-1,4- diyl group, 2-ethylbutane-1,4-diyl group, 3-methylpentane-1,5-diyl group, 3-methylpentane-1,5-diyl group, 2-methylhexane-1,6-diyl group, etc. branched aliphatic hydrocarbon groups. Among these, an alkylene group having 2 carbon atoms, that is, an ethane-1,2-diyl group (ethylene group) is preferred.

The aliphatic hydrocarbon residue for R ⁴ in formula (4) may be saturated or unsaturated, and has an alkoxy group, a cyano group, a primary to tertiary amino group in the main chain or side chain. Groups, halogen atoms and the like may be substituted.

Structural units represented by formula (4) can be present in blocks or randomly in the acylated crosslinked copolyaliphatic polycarbonate.

When the structural unit represented by formula (4) exists as a block, it is preferable that 1 or more and 10 or less of the structural units represented by formula (4) are linked to form a block, and 1 or more and 5 or less. more preferably, and particularly preferably 1 or more and 3 or less. It is preferable that the number of links is 3 or less, because both the dispersibility and binding property of the polymer binder in a hydrophobic solvent are achieved.

An acylated crosslinked copolymer aliphatic polycarbonate containing a structural unit represented by formula (4) can be obtained by a known transesterification reaction. For example, an oligomer having a structural unit represented by formula (1) in which both molecular ends are hydroxyl groups, and the ends of hydrocarbon residues represented by R ^2′ and R ^2″ in formula (2-1) a triol compound or tetraol compound having a hydroxyl group bonded to the diol compound having the structure represented by the inner brackets in formula (3), and the diol having the structure represented by the inner brackets in formula (4) and a compound are carbonate-bonded with diphenyl carbonate or the like to obtain a crosslinked copolymerized aliphatic polycarbonate, part of the hydroxyl groups at the ends of the polymer molecule are acylated by a known acylation reaction to obtain an acylated crosslinked copolymer. A polymerized aliphatic polycarbonate can be obtained.

Examples of the diol compound having the structure represented by the inner brackets in formula (4) include diethylene glycol, triethylene glycol, and polyethylene glycol. Among these, triethylene glycol is preferred.

In the acylated crosslinked copolymer aliphatic polycarbonate of the present invention, the ratio of the structural unit of formula (4) to the total sum of structural units of formulas (1) to (4) is not particularly limited, but is 5 mol% to 40 mol%. 10 mol % to 35 mol %, more preferably 15 mol % to 30 mol %, and particularly preferably 18 mol % to 22 mol %. Here, with respect to formula (1), the ratio is a value based on the repeating unit in parentheses in formula (1), not the entire formula (1).

The acylated crosslinked copolymerized aliphatic polycarbonate of the present invention may contain structural units other than the structural units represented by formulas (1) to (4) as long as the effects of the present invention are not impaired. The total ratio of the structural units of formulas (1) to (4) in the copolymerized aliphatic polycarbonate is preferably 70 mol% or more, more preferably 80 mol% or more, still more preferably 90 mol% or more, and particularly preferably 95 mol%. Above, most preferably 99 mol % or more.

In the acylated crosslinked copolymer aliphatic polycarbonate of the present invention, the ratio of the structural units represented by formulas (1) to (4) is, in terms of molar ratio, (1):(2):(3):(4 )=40-50:0.4-0.8:10-50:10-35. Here, with respect to formula (1), the ratio is a value based on the repeating unit in parentheses in formula (1), not the entire formula (1).

The weight average molecular weight (Mw) of the acylated crosslinked copolymer aliphatic polycarbonate of the present invention is not particularly limited, but is preferably 5.0×10 ³ to 1.0×10 ⁶ , more preferably 1.0×10 ^{4 to 1.0×10 4} . It is preferably 7.0×10 ⁴ . It is preferably 4.0×10 ⁴ to 5.0×10 ⁴ .

^The method for producing the acylated crosslinked copolymer aliphatic polycarbonate according to the present invention is not particularly limited. Alternatively, an oligomer is prepared in advance by reacting with phosgene or the like to form a carbonate, and hydroxyl groups are bonded to the ends of the oligomer and the hydrocarbon residues represented by R ^2′ and R ^2″ in formula (2-1). a triol compound or a tetraol compound having a formula (3), a diol compound having a structure represented by the inner brackets in the formula (3), and a diol compound having a structure represented by the inner brackets in the formula (4), By reacting diphenyl carbonate or phosgene to form a carbonate bond, random polymerization is performed to obtain a crosslinked copolymerized aliphatic polycarbonate, and some of the hydroxyl groups at the ends of the polymer molecule are acylated by a known acylation reaction. , an acylated cross-linked copolymerized aliphatic polycarbonate can be obtained.

In addition, a diol compound in which a hydroxyl group is bonded to the terminal of an aliphatic hydrocarbon residue represented by R ¹ is reacted with diphenyl carbonate or phosgene to form a carbonate, and a structural unit represented by the formula (1) is included. An oligomer is prepared, and a diol compound having a structure represented by the inner brackets in formula (3) is reacted with diphenyl carbonate or phosgene to form a carbonate to prepare an oligomer containing a structural unit represented by formula (3). Then, the diol compound having the structure represented by the inner brackets in the formula (4) is reacted with diphenyl carbonate or phosgene to form a carbonate to prepare an oligomer containing the structural unit represented by the formula (1). and a triol compound or a tetraol compound having hydroxyl groups bonded to the ends of the hydrocarbon residues represented by R ^2′ and R ^2″ in formula (2-1) with diphenyl carbonate or phosgene. and carbonate bonding to effect block polymerization to obtain a crosslinked copolymerized aliphatic polycarbonate.

（式（５－１）～（５－４）および式（６）中、Ｒ^５は、それぞれ独立して水素原子又はアシル基を表す。）
式（５－１）～（５－４）および式（６）で表される前記ポリマー分子末端のアシル基と水素原子との割合が、ポリマー平均の濃度（ｅｑ／Ｔ）で（１００：０）～（６５：３５）である。 (acylation)
The acylated crosslinked copolymerized aliphatic polycarbonate according to the present invention is an acylated crosslinked copolymerized aliphatic polycarbonate in which part of the hydroxyl groups at the ends of the polymer molecules of the crosslinked copolymerized aliphatic polycarbonate is acylated at a specific ratio. be. That is, the polymer molecule terminals of the acylated crosslinked copolymerized aliphatic polycarbonate according to the present invention are represented by the following formulas (5-1): to (5-4), wherein the terminal group bonded to R 1 to R 4 on the right end of formulas ( ¹ ) to ( ⁴ ) is represented by the following formula (6) and

(In formulas (5-1) to (5-4) and formula (6), each R ⁵ independently represents a hydrogen atom or an acyl group.)
The ratio of acyl groups and hydrogen atoms at the ends of the polymer molecules represented by formulas (5-1) to (5-4) and formula (6) is (100:0) at the polymer average concentration (eq/T). ) to (65:35).

Adhesion of the polymer binder containing the acylated crosslinked copolymerized aliphatic polycarbonate to the aluminum foil when the polymer average concentration (eq/T) is in the range of (100:0) to (65:35) improves.

If the adhesiveness of the polymer binder is high, the amount of the polymer binder used can be reduced, which is expected to reduce the internal resistance of the all-solid-state battery and improve the ionic conductivity.

Acyl groups in the acylated crosslinked copolymer aliphatic polycarbonate include formyl group (also known as methanoyl group), acetyl group (also known as ethanoyl group), propionyl group (also known as propanoyl group), benzoyl group, and acrylyl group (also known as : propenoyl group), among which acetyl group and benzoyl group are preferred, and acetyl group is particularly preferred.

(polymer binder)
The polymeric binder according to the second aspect of the present invention can contain an acylated crosslinked copolyaliphatic polycarbonate and a lithium salt. Containing a lithium salt is preferable because the ion conductivity of the polymer binder is improved. The proportion of the acylated crosslinked copolymer aliphatic polycarbonate and the lithium salt in the polymer binder is, for example, 100 to 200 parts by weight of the lithium salt per 100 parts by weight of the acylated crosslinked copolymer aliphatic polycarbonate.

For example, when using a sulfide as a solid electrolyte in an all-solid-state secondary battery, the sulfide may become brittle or denatured by heat, which may reduce the ionic conductivity, so the binder should be removed by heat treatment. may not be possible. In the present invention, by including a lithium salt in the polymer binder, the lithium salt contained in the polymer binder enhances the ionic conduction of the positive electrode, the negative electrode, or the solid electrolyte layer without finally removing the binder. A supporting effect can be obtained.

LiN( _SO2F ) _{2 (} generic name: LiFSI), LiN( _SO2CF3 ) _{2 (} generic name: LiTFSI), LiN( _{SO2C2H 5} ) Lithium salts such as ₂ , LiPF ₆ and LiBF ₄ can be mentioned. This lithium salt may contain other components such as inorganic salts of alkali metals. Among them, LiTFSI is preferable.

The polymer binder of the present invention is also used to bind the positive electrode mixture, negative electrode mixture, and solid electrolyte of an all-solid secondary battery. That is, it is desirable that the polymer binder of the present invention permeate between the positive electrode mixture, the negative electrode mixture, and the solid electrolyte during the manufacturing process. When manufacturing an all-solid secondary battery using a sulfide for the solid electrolyte layer, a slurry using a hydrophobic solvent such as chloroform, anisole, or butyl butyrate is preferably used in the manufacturing process. Since the polymer binder of the present invention is well dispersed in a hydrophobic solvent, it is suitably used when a sulfide is used for the solid electrolyte layer.

Examples of hydrophobic solvents include aliphatic hydrocarbons such as pentane, hexane, heptane, octane, nonane, and decane; aromatic hydrocarbons such as benzene, toluene, and xylene; and halogen-substituted hydrocarbons such as chloroform, dichloromethane, and carbon tetrachloride. hydrogen, halogen-substituted aromatic hydrocarbons such as chlorobenzene and bromobenzene; aromatic ethers such as anisole; aliphatic esters such as butyl butyrate; and aliphatic carbonates such as diethyl carbonate. be done.

Therefore, from the viewpoint that the polymer binder of the present invention preferably has high dispersibility in a hydrophobic solvent, the dispersibility of butyl butyrate or diethyl carbonate is preferably 70% or more, more preferably 80% or more. more preferred.

However, the dispersion ratio is calculated by the following formula (a).
Dispersion rate (%) = (residual amount/theoretical amount) x 100 (a)
The "theoretical amount" in the above formula means the concentration (% by mass) of the polymer binder in the dispersion, assuming that the total amount of the sample polymer binder is dispersed in butyl butyrate or diethyl carbonate, and the It is the mass (g) of the polymer binder calculated from the mass (g) of the dispersion. The "remaining amount" is the mass (g) of the sample polymer binder that actually remained when the sampled dispersion was dried to remove butyl butyrate or diethyl carbonate.

In addition, when a solid electrolyte is contained in a polymer binder, the solid electrolyte generally has low solubility in a hydrophobic solvent, so that it does not disperse in the hydrophobic solvent, and the solid electrolyte may separate and precipitate. . Therefore, when a solid electrolyte is contained in the polymer binder of the present invention, it can be dispersed in a hydrophobic solvent by using an acylated crosslinked copolymerized aliphatic polycarbonate. Specifically, an acylated crosslinked copolymer aliphatic polycarbonate and a solid electrolyte are mixed and dispersed in a hydrophilic solvent such as THF, and the dispersion is dried to evaporate the solvent, thereby forming a solid in a polymer binder. Electrolytes can be included.

The all-solid secondary battery of the present invention has a positive electrode, a negative electrode, and a solid electrolyte layer positioned between the positive electrode and the negative electrode, at least one of which contains the polymer binder of the present invention. , or used in manufacturing. Further, the all-solid secondary battery of the present invention may contain a binder other than the polymer binder of the present invention, or may be used during production. Examples of binders other than the polymer binder of the present invention include styrene-butadiene rubber, PVDF, PTFE, and acrylic resins.

Solid electrolytes used in the solid electrolyte layer include solid sulfides represented by Z ₂ S—M _x S _y . However, Z in the formula is Li or Na, M is P, Si, Ge, B, Al or Ga, and x and y are numbers based on stoichiometry according to the type of M. Examples _{of MxSy} include solid sulfides such _{as P2S5 , SiS2 , GeS2} , _{B2S3 , Al2S3} , _Ga2S3 .

Examples of Z ₂ S—M _x S _y include Li ₂ SP ₂ S ₅ and Li ₂ S—SiS ₂ . Moreover, the solid sulfides described above may contain M _x S _y with different Ms.

Furthermore, a solid sulfide represented by Z ₂ S—M _n S _m —ZX can also be used as a solid electrolyte. where Z is Li, M is P, Si, Ge, B, Al or Ga, X is Cl, Br or I, and n and m are based on stoichiometry depending on the type of M is a number.

Examples _{of MnSm include solid} sulfides such _{as P2S5} , _SiS2 , _GeS2 , _{B2S3 , Al2S3} , _Ga2S3 .

Examples of Z ₂ S—M _n S _m —ZX include Li ₂ SP ₂ S ₅ —LiCl, Li ₂ SP ₂ S ₅ —LiBr—LiCl, and Li ₂ S—SiS ₂ —LiBr. be done.

Other solid sulfide electrolytes used in the solid electrolyte layer include, for example, Li ₁₀ GeP ₂ S ₁₂ (common name: LGPS), Li ₁₀ SnP ₂ S ₁₂ , and Li ₆ PS ₅ Cl. These solid sulfides may be used singly or in combination.

In addition to solid sulfides, solid oxides such as Li ₇ La ₃ Zr ₂ O ₁₂ (common name: LLZO) and Li _1.3 Al _0.3 Ti _1.7 (PO ₄ ) ₃ (common name: LATP) can also be used as solid electrolytes. These solid electrolytes may be used alone or in combination.

A preferred solid electrolyte is Li ₂ SP ₂ S ₅ . For example, the molar ratio of Li ₂ S and P ₂ S ₅ may be Li ₂ S:P ₂ S ₅ =50:50 to 95:5. Especially preferred.

The positive electrode contains the positive electrode active material and the solid electrolyte, and may further contain the polymer binder of the present invention.

As the positive electrode active material, a known positive electrode active material that can be used for all-solid secondary batteries can be used. Examples include LiCoO ₂ , LiNiO ₂ , Li _1+x Ni _1/3 Mn _1/3 Co _1/3 O ₂ (where x is a positive number), LiMn ₂ O ₄ , Li _1+x Mn _2-xy M _y O ₄ (M is at least one metal selected from Al, Mg, Co, Fe, Ni, and Zn; x and y are positive numbers), Li _x TiO _y (x and y are positive numbers ), LiMPO ₄ (M is Fe, Mn, Co or Ni), and the like.

The positive electrode may contain other components such as a conductive aid in addition to the positive electrode active material, the solid electrolyte, and the polymer binder of the present invention.

Examples of conductive aids include carbon black such as acetylene black and ketjen black, carbon nanotubes, natural graphite, artificial graphite, and vapor grown carbon fiber (VGCF (registered trademark)).
The content of other components in the positive electrode is not particularly limited, but the content is preferably 10% by mass or less.

The positive electrode may be formed on a current collector. As the current collector, for example, a plate-shaped metal such as aluminum can be used.

The negative electrode contains the negative electrode active material and the solid electrolyte, and may further contain the polymer binder of the present invention. As the negative electrode active material, known negative electrode active materials that can be used in all-solid secondary batteries can be used. Examples include carbon materials such as _mesocarbon microbeads, graphite, hard carbon and soft carbon, lithium titanium oxides such as _{Li4Ti5O12 ,} and metals such as Li.

In addition to the negative electrode active material and the solid electrolyte, the negative electrode may contain other components such as an inorganic salt of an alkali metal and a conductive aid. Other components exemplified in the description of the solid electrolyte layer can be used as other components for the negative electrode. The content of other components in the negative electrode is preferably 10% by mass or less.

The negative electrode may be formed on a current collector. As the current collector, for example, plate-shaped metal such as copper or stainless steel can be used.

The all-solid secondary battery of the present invention constitutes one cell with a positive electrode, a solid electrolyte layer and a negative electrode. An all-solid secondary battery may be configured with only one cell, but a plurality of cells may be connected in series or in parallel to form an assembly.

A positive electrode, a negative electrode or a solid electrolyte layer is prepared by a step of dissolving or dispersing the raw materials, that is, the substances described in each explanation and the polymer binder of the present invention in an organic solvent to obtain a slurry (slurry manufacturing step); It can be obtained through a process of coating and drying (coating and drying process).

As the organic solvent, one that dissolves or disperses the polymer binder of the present invention without affecting the properties of the solid electrolyte and active material is used. Specifically, saturated chain hydrocarbons such as n-pentane, n-hexane, heptane, n-octane, nonane, decane, undecane, dodecane, tridecane, and tetradecane; halogen-substituted saturated hydrocarbons such as carbon tetrachloride, chloroform, and dichloroethane; Chain hydrocarbons, saturated cyclic hydrocarbons such as cyclohexane, cycloheptane and cyclooctane, aromatic hydrocarbons such as benzene, toluene and xylene, halogen-substituted aromatic hydrocarbons such as chlorobenzene and bromobenzene, dioxane, methyl ethyl ketone, trioxa Oxygen-containing chain hydrocarbons such as undecane, trioxanonane, trioxapentadecane, diethylene glycol dimethyl ether, triethylamine, propanenitrile, dimethyldiazohexane, trimethyltriazononane, N,N,N',N'-tetramethylethylenediamine, N,N ,N′,N″,N″-pentamethyldiethylenetriamine and other nitrogen-containing saturated hydrocarbons, oxygen-containing aromatic hydrocarbons such as anisole, aliphatic esters such as butyl butyrate, and fats such as dimethyl carbonate, diethyl carbonate, and propylene carbonate. group carbonates, and the like. When a sulfide is used for the solid electrolyte layer, the organic solvent is preferably a hydrophobic solvent such as chloroform, anisole, butyl butyrate, diethyl carbonate. The organic solvent is used in such an amount that the solution or dispersion of the raw materials can be applied.

Conditions for dissolving or dispersing the solid electrolyte and the polymer binder of the present invention in an organic solvent are not particularly limited as long as sufficient dissolution or dispersion is performed. Dissolution or dispersion can be performed at room temperature (for example, 25° C.), and if necessary, cooling or heating may be performed. In addition, if necessary, the dissolution or dispersion may be carried out under normal pressure, reduced pressure or increased pressure.

A positive electrode, a negative electrode, and a solid electrolyte layer can be obtained by applying a slurry of raw materials for a positive electrode, a negative electrode, or a solid electrolyte on a substrate, respectively, and then drying the obtained coating film.

The substrate to which the slurry is applied is not particularly limited. For example, a current collector or solid electrolyte layer or positive electrode can be used as a substrate if the production of the solid electrolyte slurry is carried out at the same time as the production of the positive electrode. Examples of coating methods include coating with an applicator, doctor blade, bar coater, brush coating, roll coating, spray coating, electrospray coating and the like.

After stacking the positive electrode, the solid electrolyte layer and the negative electrode thus obtained in this order, they are pressed in the stacking direction to adhere to each other to form a laminate. The all-solid secondary battery of the present invention can be obtained by heat-treating the laminate as necessary.

The heat treatment of the laminate can be performed under an inert atmosphere such as nitrogen or argon, if necessary. Further, the heat treatment may be performed under normal pressure, reduced pressure, or increased pressure. Furthermore, the heat treatment is preferably performed by heating at a temperature below which the crystal structure of the solid electrolyte does not change. A more preferable heat treatment temperature is a temperature between T-25°C and T+50°C, where T°C is the decomposition initiation temperature of the polymer binder of the present invention. The heat treatment time varies depending on the size of the laminate, the number of layers, and the heat treatment temperature, but is usually 3 to 60 minutes, more preferably 5 to 30 minutes. Moreover, the solid electrolyte layer, the positive electrode, and the negative electrode may be individually heat-treated, or they may be laminated and then treated.

(Example)
EXAMPLES The present invention will be specifically described below with reference to Examples, but the scope of the present invention is not limited by these.

<Weight average molecular weight, molecular weight distribution>
The weight average molecular weight (Mw) and molecular weight distribution (Mw/Mn) were obtained from the standard polystyrene equivalent weight average molecular weight (Mw) and number average molecular weight (Mn) measured by gel permeation chromatography (GPC). The molecular weight distribution (Mw/Mn) is a value represented by the ratio of weight average (Mw) to number average molecular weight (Mn).

GPC measurement was performed using a WATERS 410 differential refractometer manufactured by Waters Corporation as a detector, a MODEL 510 high performance liquid chromatography as a pump, and two Shodex GPC HFIP-806L columns connected in series. The measurement conditions were a flow rate of 1.0 mL/min, chloroform was used as a solvent, and 0.1 mL of a solution having a sample concentration of 0.2 mg/mL was injected.

<Glass transition temperature>
The glass transition temperature was measured by heating 10 mg of a sample from −160° C. to 100° C. at a rate of 20° C./min in a nitrogen atmosphere using a differential scanning calorimeter (Q20) manufactured by T.A. Instruments Co., Ltd. It was measured.

<Polymer structure>
The structure of the polymer was confirmed by measuring ¹ H-NMR and ¹³ C-NMR in a heavy chloroform solution using a nuclear magnetic resonance apparatus JNM-ECA600 spectrometer manufactured by JEOL Ltd.

<Hydrophobic Solvent Dispersibility>
The dispersibility of polycarbonate was evaluated by the following method.
0.4 g of polymer, 0.6 g of LiTFSI, and 5.7 g of THF were added to a 30 mL vial, thoroughly stirred, dried at 65° C. for 5 hours, and then dried under reduced pressure at 65° C. for 24 hours.
Next, butyl butyrate or diethyl carbonate was placed in a 30 mL vial so that the polymer binder was 10% by mass, and stirred at 25° C. for 3 hours. After stirring was stopped, the mixture was allowed to stand for 0 minute and 24 hours, and 1 g of the mixed liquid was dispensed into a weighed 30 mL vial. In the case of butyl butyrate, it was dried at 160°C for 3 hours and then dried at 65°C under reduced pressure for 2 hours. In the case of diethyl carbonate, it was dried at 130° C. for 3 hours and then dried at 65° C. under reduced pressure for 2 hours.
After drying, a 30 mL vial was weighed and the mass of residue was calculated. From the calculated residual amount, the dispersion ratio of the solution was calculated using the following formula (c).
Dispersion ratio = amount of remaining material/theoretical amount of remaining material x 100 (c)
○ (good): dispersion rate is 90% or more × (poor): dispersion rate is less than 90%

<Heat resistance>
The heat resistance of the polymer binder film was evaluated at the 5% weight loss temperature _Td5 . The 5% weight loss temperature _Td5 was measured using TG-DTA 8122/C-SL manufactured by Rigaku Co., Ltd. After heating 15 mg of the sample from 20°C to 110°C at a rate of 10°C/min in a nitrogen atmosphere. , held for 10 minutes, further heated to 500° C., held for 30 minutes, and measured. The temperature at which the weight was reduced by 5% based on the weight after holding at 110°C for 10 minutes was defined as the 5% weight reduction temperature _Td5 .

<Aluminum foil adhesive strength>
2.5 mL of a THF dispersion containing 30% by mass of a polymer binder was evenly coated on an aluminum foil so as to have a length of 150 mm and a width of 60 mm.
Next, after drying at 100° C. for 1 hour, it was further dried at 60° C. under reduced pressure for 2 hours. Another aluminum foil was overlaid on the obtained sheet sample and pressed at 60° C. and 0.5 MPa for 2 minutes. The pressed aluminum sheet was cut into a length of 200 mm and a width of 25 mm so as to include the polymer portion, and a sample for peel test was prepared. A peel test sample was set in AG-100B manufactured by Shimadzu Corporation with a chuck distance of 20 mm, and the peel force (N) was measured at a rate of 10 mm/min. The average value of the peel strength between 60 and 100 mm in the measurement range of 200 mm was calculated and used as the adhesive strength of the polymer binder to the aluminum foil.

<Ionic conductivity measurement>
Ionic conductivity was obtained by the following method.
A circle having a diameter of 6 mm was cut out from each of the polymer binder films obtained by the method described later, and sandwiched between two stainless steel plates to measure the impedance of the polymer binder film.
Impedance was measured at 30 to 80° C. using an impedance analyzer manufactured by Biologic with a measurement frequency range of 100 to 1,000,000 Hz and an amplitude voltage of 10 mV. Ionic conductivity was calculated from the obtained impedance using the following formula (b).
σ=L/(R×S) (b)
In the above formula (b), σ is the ionic conductivity (S/cm), R is the impedance (Ω), S is the cross-sectional area of the polymer binder film (cm ² ), and L is the thickness of the polymer binder film (cm). is.

<Production Example 1>
A crosslinked copolymerized aliphatic polycarbonate was synthesized by the following procedure.

(Preparation of oligomer)
69.71 g (0.40 mol) of 1,10-decanediol, diphenyl carbonate (manufactured by Aldrich ) 77.1 g (0.36 mol) and 0.30 mg (4 μmol) of sodium hydrogencarbonate were added, and the temperature was raised to 200° C. while stirring. Next, the temperature was raised at 0.5° C./min while the pressure was reduced at 1 kPa/min, and the mixture was stirred for 2 hours. After that, the mixture was stirred at 260° C. for 15 minutes under reduced pressure to carry out a polymerization reaction to obtain an oligomer.

(Copolymerization reaction)
Next, in the 0.3 L three-necked flask, 0.28 g (0.002 mol) of pentaerythritol (manufactured by Wako Pure Chemical Industries, Ltd.), 36.89 g (0.12 mol) of spiroglycol, 12.14 g of triethylene glycol ( 0.08 mol), 44.7 g (0.21 mol) of diphenyl carbonate, and 0.18 mg (2 μmol) of sodium hydrogencarbonate were added, and the temperature was raised to 200° C. while stirring. Next, the temperature was raised at 0.5° C./min while the pressure was reduced at 1 kPa/min, and the mixture was stirred for 2 hours. Then, the mixture was stirred at 260° C. for 30 minutes under reduced pressure to carry out a polymerization reaction. After completion of the reaction, the three-necked flask was cooled to obtain a crosslinked copolymerized aliphatic polycarbonate R1. The weight average molecular weight of the resulting crosslinked copolymerized aliphatic polycarbonate R1 was 2.9×10 ⁴ (Mw/Mn=2.0). The structure of the resulting crosslinked copolymerized aliphatic polycarbonate R1 was confirmed by ¹ H-NMR and ¹³ C-NMR (FIGS. 1 and 2).

<Example 1>
The crosslinked copolymerized aliphatic polycarbonate R1 obtained in Production Example 1 was acylated by the following procedure.

(Acylation reaction)
A 1 L three-necked flask equipped with a stirrer, a thermometer, and a reflux condenser was charged with 5 g of the crosslinked copolymerized aliphatic polycarbonate R1 obtained in Production Example 1, 69 g (0.9 mol) of pyridine, and 600 mL of NMP. Stirred for 30 minutes. Next, 104 g (1.0 mol) of acetic anhydride was added, and the mixture was heated to 70° C. and stirred for 6 hours. After returning to room temperature, methanol was added to the reaction solution to precipitate a polymer, which was then filtered. The residue was transferred to a beaker, dissolved in chloroform, and separated with pure water three times. After liquid separation, the chloroform phase was added to methanol, and the precipitate was collected by filter filtration. The obtained acylated crosslinked copolymer aliphatic polycarbonate had a weight average molecular weight of 4.6×10 ⁴ (Mw/Mn=1.6). The glass transition temperature of the acylated crosslinked copolymerized aliphatic polycarbonate was -25°C. The structure of the acylated crosslinked copolymer aliphatic polycarbonate was confirmed by ¹ H-NMR and ¹³ C-NMR (Figs. 3 and 4). The concentrations of acetyl groups and hydroxyl groups in the polymer were calculated from FIGS. 3 and 4. FIG. The unit of concentration was the number of equivalents per ton of polymer (eq/T). From the obtained acetyl group and hydroxyl group concentrations, the acetylation rate (acylation rate) was calculated using the following formula (c).
Acetylation rate (acylation rate) = acetyl group concentration/(acetyl group concentration + hydroxyl group concentration) x 100 (c)
The acetylation rate (acylation rate) of the acylated crosslinked copolymer aliphatic polycarbonate was determined to be 75%.

(Manufacture of polymer binder)
The acylated crosslinked copolymer aliphatic polycarbonate obtained in Example 1 was mixed with LiTFSI weighed so that the LiTFSI content was 60% by mass, and the mixture was stirred well in THF to give a concentration of 30% by mass. A dispersion of polymer binder was obtained.

The dispersibility of the polymer binder was evaluated using butyl acetate and diethyl carbonate as hydrophobic solvents. Table 1 shows the results.

(Production of polymer binder film)
1 mL of a THF dispersion of a polymer binder was uniformly applied to one side of the aluminum foil film using a micropipette so as to form a 5 cm square. After drying at 65° C. for 3 hours, it was further dried at 65° C. for 4 hours under reduced pressure to obtain a polymer binder film composed of a transparent polymer binder with a LiTFSI content of 60 mass %. The measured Tg of the obtained polymer binder film was -55°C, and the heat resistance (T _d5 ) was 267°C. Further, when the aluminum foil adhesive strength of the obtained polymer binder film was measured, it was 8.8N. Table 1 shows the results.

<Comparative Example 1>
A polymer binder and a polymer binder film were produced in the same manner as in Example 1 without acylating the crosslinked copolymerized aliphatic polycarbonate R1 of Production Example 1, and Tg, heat resistance, aluminum foil adhesive strength, Hydrophobic solvent dispersibility was measured. Table 1 shows the results. The polymer binder film using the crosslinked copolymerized aliphatic polycarbonate R1 was inferior to that of Example 1 in adhesive strength to the aluminum foil.

Even a cross-linked copolymerized aliphatic polycarbonate having all —OH ends (Comparative Example 1) has a relatively high adhesive strength. It is important to suppress the peeling of the electrode layer, and it is necessary for the polymer binder to further improve the adhesive strength to the current collector foil. In the acylated crosslinked copolymerized aliphatic polycarbonate (Example 1) according to the present invention, the adhesive strength is increased as described above. In the adhesion test, an adhesion force of 1 N corresponds to holding 100 g of metal particles, so as shown in Example 1, an increase of 1.8 N compared to that of Comparative Example 1 indicates that all solids It can be said that this greatly contributes to increasing the area of the battery.

Claims (9)

Including structural units represented by the following formulas (1) to (4),

(In formula (1), R ¹ represents an aliphatic hydrocarbon residue having 2 to 20 carbon atoms, and x represents an integer of 3 to 100.)

(In formula (2), R ² is the following formula (2-1)

, R ^2′ and R ^2″ each independently represent an aliphatic hydrocarbon residue having 0 to 5 carbon atoms, and R ^2′″ is a hydrogen atom or a C 1 to 5 Represents an aliphatic hydrocarbon residue. )

(In formula (3), R ³ represents an aliphatic hydrocarbon residue that has a spiro structure and may contain a heteroatom in the structure.)

(In formula (4), ^R4 represents an aliphatic hydrocarbon residue having 2 to 10 carbon atoms, and m represents an integer of 1 to 30.)
The terminal of the polymer molecule has any structure in which the terminal group bonded to the carbonate oxygen atom on the left end of the formulas (1) to (4) is represented by the following formulas (5-1) to (5-4), respectively. and the terminal group bonded to R ¹ to R ^{4 on the right end of the formulas (1) to (4} ) has a structure represented by the following formula (6),

(In formulas (5-1) to (5-4) and formula (6), each R ⁵ independently represents a hydrogen atom or an acyl group.)
The ratio of acyl groups and hydrogen atoms at the ends of the polymer molecules represented by formulas (5-1) to (5-4) and formula (6) is (100: 0) to (65:35),
Acylated crosslinked copolymerized aliphatic polycarbonate. 2. The acylated crosslinked copolymerized aliphatic polycarbonate according to claim 1, wherein the acyl group represented by ^R5 is an acetyl group or a benzoyl group. The R ¹ represents an aliphatic hydrocarbon residue having 8 to 12 carbon atoms, x represents an integer of 60 to 90,
R ² represents an aliphatic hydrocarbon residue in which R ^2″ in the formula (2-1) has 1 or more and 2 or less carbon atoms,
R ³ has 1 to 2 spiro atoms, and the heteroatom is an oxygen atom or a sulfur atom;
3. The acylated crosslinked copolymerized aliphatic polycarbonate according to claim 1 or 2, wherein ^R4 represents an aliphatic hydrocarbon residue having 2 or more and 4 or less carbon atoms, and m represents an integer of 1 or more and 3 or less. R ¹ is an alkylene group having 10 carbon atoms, R ² is an alkylene group having 1 carbon atoms, and R ^2″ in the formula (2-1) is an alkylene group having 1 carbon atoms, and R ³ is 2,2′-( 2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diyl)dipropanediyl group, wherein R ⁴ is an alkylene group having 2 carbon atoms and m is an integer of 3; The acylated crosslinked copolymerized aliphatic polycarbonate according to any one of claims 1 to 3. The ratio of the structural units represented by the above formulas (1) to (4) is (1):(2):(3):(4) = 40 to 50:0.4 to 0.8 in terms of molar ratio. : 10-50: 10-35. A polymer binder for an all-solid-state battery, comprising the acylated crosslinked copolymer aliphatic polycarbonate according to any one of claims 1 to 5 and a lithium salt. 7. The polymeric binder for an all-solid-state battery according to claim 6, wherein said lithium salt comprises LiTFSI. An all-solid secondary battery comprising the acylated crosslinked copolymerized aliphatic polycarbonate according to any one of claims 1 to 5. An all-solid secondary battery comprising the polymer binder for an all-solid-state battery according to claim 6 or 7.