Battery

Abstract

The present disclosure provides a battery which comprises a positive electrode, a negative electrode, and an electrolyte that is disposed between the positive electrode and the negative electrode, wherein: the positive electrode contains a positive electrode active material and a polymer having an ability to preferentially conduct alkali metal ions; the porosity of pores having a size of 0.1 to 100 μm in the positive electrode is 23% or more as determined by a mercury intrusion method; the electrolyte is a film which includes a polymer having an ability to preferentially conduct the alkali metal ions; and the polymer having the ability to preferentially conduct the alkali metal ions in the electrolyte is swollen by a solution that includes an additive for film formation and an organic solvent.

Description

battery

[0001] The present disclosure relates to batteries.

[0002] Batteries such as lithium-ion batteries, which charge and discharge through the movement of metal ions between a positive electrode and a negative electrode, have been the subject of vigorous research due to their high capacity (Patent Documents 1 to 3). Known electrolytes for lithium-ion batteries and the like include solutions of lithium salts containing organic solvents or ionic liquids. However, from the perspectives of safety and processability, research is also being conducted on solid electrolytes and polymer electrolytes (Non-Patent Documents 1 and 2). In addition to lithium-ion batteries, research is also being conducted on batteries using other alkaline ions, such as sodium and potassium, which are more abundant than lithium.

[0003] JP 2021-114411 A JP 2003-249224 A JP 2022-121093 A

[0004] Advanced Energy Materials, 2019, 9, 1902767Macromolecular Rapid Communications, 2023, 44, 2200865

[0005] Secondary batteries such as lithium ion batteries are required to be capable of high-speed charge and discharge. However, the inventors have conducted extensive research and found that cells using polymer electrolytes have poor cycle characteristics during high-speed charge and discharge.

[0006] The present disclosure has been made in consideration of the above circumstances, and aims to provide a battery that exhibits high cycle stability when charged and discharged at a rate of 1 C or higher.

[0007] [1] A battery comprising a positive electrode, a negative electrode, and an electrolyte disposed between the positive electrode and the negative electrode, wherein the positive electrode contains a positive electrode active material and a polymer capable of preferentially conducting alkali metal ions and has a porosity of 23% or more at 0.1 to 100 μm as measured by mercury porosimetry, the electrolyte is a membrane containing the polymer capable of preferentially conducting alkali metal ions, and the polymer capable of preferentially conducting alkali metal ions in the electrolyte is swollen with a solution containing a film-forming additive and an organic solvent. [2] The battery of [1], wherein the film-forming additive is fluoroethylene carbonate or vinylene carbonate. [3] The battery of [1] or [2], wherein the organic solvent is one or more solvents selected from the group consisting of carbonate-based solvents, ether-based solvents, fluorine-based solvents, nitrile-based solvents, lactone-based solvents, phosphate ester-based solvents, and sulfone-based solvents. [4] The battery according to any one of [1] to [3], wherein the polymer capable of preferentially conducting alkali metal ions contained in the positive electrode and the electrolyte has an alkali metal ion and an anionic functional group having the alkali metal ion as a counter cation. [5] The battery according to [4], wherein the alkali metal ion includes a lithium ion or a sodium ion. [6] The battery according to [4], wherein the anionic functional group has one or more groups selected from the group consisting of an alkali metal substituted sulfonylimide group, an alkali metal substituted sulfonic acid group, an alkali metal substituted carboxylic acid group, and an alkali metal substituted phenolic hydroxyl group.

[0008] According to the present disclosure, it is possible to provide a battery that exhibits high cycle stability when charged and discharged at a rate of 1 C or higher.

[0009] Fig. 1 is a scanning electron microscope image of cathode material 1. Fig. 2 is a scanning electron microscope image of cathode material 2.

[0010] The battery of this embodiment includes a positive electrode, a negative electrode, and an electrolyte disposed between the positive electrode and the negative electrode. The positive electrode contains a positive electrode active material and a polymer capable of preferentially conducting alkali metal ions, and has a porosity of 23% or more at 0.1 to 100 μm as measured by mercury porosimetry. The electrolyte is a membrane containing a polymer capable of preferentially conducting alkali metal ions. In the electrolyte, the polymer capable of preferentially conducting alkali metal ions is swollen with a solution containing a film-forming additive and an organic solvent.

[0011] According to the present disclosure, a battery exhibiting high cycle stability when charged and discharged at a rate of 1 C or higher (e.g., 2 C) can be provided. The inventors speculate that the reason for this effect is as follows: A positive electrode having a positive electrode active material and a polymer capable of preferentially conducting alkali metal ions has pores with a specific porosity, thereby suppressing changes in the electrode structure during cycling. Furthermore, in the electrolyte, the polymer capable of preferentially conducting alkali metal ions is swollen by a solution containing a film-forming additive and an organic solvent, making decomposition of the organic solvent less likely. It is believed that these factors act in combination to enhance cycle stability.

[0012] The battery of this embodiment may be a battery that charges and discharges by the movement of alkali metal ions, such as a lithium ion battery or a sodium ion battery. The battery may be a primary battery, a secondary battery, or a solid-state battery.

[0013] In any case in this specification, examples of the "substituent" include both organic groups and groups other than organic groups (inorganic groups).

[0014] As used herein, the term "organic group" refers to a group having a chemical structure in which at least one hydrogen atom has been removed from an organic compound. In any case, the term "organic group" as used herein can refer to, regardless of the valence of the organic group, a hydrocarbon group or a group in which some carbon atoms of a hydrocarbon group have been replaced with heteroatoms, or a group in which at least one hydrogen atom of a hydrocarbon group or a group in which some carbon atoms of a hydrocarbon group have been replaced with heteroatoms, substituted with a substituent. When the organic group has a ring structure, the ring may be either a heterocyclic ring or a carbocyclic ring, and may be either a monocyclic ring or a fused ring.

[0015] In any case herein, the "hydrocarbon group" can be exemplified by both an aliphatic hydrocarbon group and an aromatic hydrocarbon group. Furthermore, in any case herein, the "hydrocarbon group" can be exemplified by both a saturated hydrocarbon group and an unsaturated hydrocarbon group. In any case herein, the "aliphatic hydrocarbon group" can be exemplified by both a linear hydrocarbon group, a branched hydrocarbon group, and a cyclic hydrocarbon group.

[0016] In this specification, an "aromatic hydrocarbon group" refers to a hydrocarbon group having an aromatic moiety such as a benzene ring, and may also have an aliphatic moiety. In addition, in this specification, a "cyclic hydrocarbon group" refers to a hydrocarbon group having an aliphatic carbon ring moiety, and may also have a linear or branched aliphatic moiety.

[0017] The "heteroatom" substituting the carbon atom is not particularly limited, but examples include a boron atom, an oxygen atom, a nitrogen atom, a silicon atom, a phosphorus atom, and a sulfur atom. Specifically, the organic group may contain a linking group containing a heteroatom, such as an -O- (ether bond), an -S- (thioether bond), a sulfonyl group, a sulfinyl group, a secondary amino group, or a tertiary amino group.

[0018] In any case, specific examples of the "organic group" used in this specification include a substituted or unsubstituted hydrocarbon group, a group having a chemical structure formed by substituting one or more carbon atoms (methylene groups) in a hydrocarbon group with a linking group containing a hetero atom (the linking group may be a divalent linking group) such as -O- (ether bond), -S- (thioether bond), -C(=O)-, -C(=O)O-, or -C(=O)NR- (R is a monovalent organic group), or a group in which a hydrogen atom of the group is substituted with a substituent such as a halogen atom, and a group having a heterocycle.

[0019] In any case, the "inorganic group" in this specification can be exemplified by both an electron-withdrawing group and an electron-donating group, and specifically, a halogen atom, -NH ２ , -NH ３ ＋ , —CN, sulfonic acid group and its salts or esters, —NO ２ etc.

[0020] <Polymer Capable of Preferentially Conducting Alkali Metal Ions> A polymer capable of preferentially conducting alkali metal ions (hereinafter also simply referred to as "polymer") may be any polymer that satisfies at least one of the following conditions (A) and (B). The polymer may simply be referred to as a polymer capable of conducting alkali metal ions. (A) When the transference number of alkali metal ions is measured at room temperature (25°C) for a composition containing 33 mass% of polymer and 67 mass% of nonionic plasticizer, the transference number of alkali metal ions is 0.4 or greater. (B) When the transference number of alkali metal ions is measured at room temperature (25°C) for a composition containing 31.9 mass% of polymer, an alkali metal salt, and the remainder of the total amount of nonionic plasticizer, and having an alkali metal ion concentration of 0.3 mol / L, the transference number of alkali metal ions is 0.4 or greater.

[0021] In (A) and (B), the transport number of the alkali metal ion may be 0.5 or more, 0.6 or more, or 0.7 or more. The transport number of the alkali metal ion may be, for example, 0.9 or less.

[0022] When the polymer has an anionic functional group, the alkali metal ion contained in the alkali metal salt contained in the compositions (A) and (B) may be the same as the counter cation of the anionic functional group. The alkali metal salt may be a bis(trifluoromethanesulfonyl)imide salt (TFSI salt).

[0023] The non-ionic plasticizer may be at least one of an organic solvent and another resin such as a fluorine-based resin.

[0024] The organic solvent may be an aprotic solvent. The aprotic solvent may be at least one selected from the group consisting of carbonate-based solvents, fluorine-based solvents, and ether-based solvents. The organic solvent may be a mixed solvent of ethylene carbonate and propylene carbonate (volume ratio 1:1).

[0025] The fluororesin is preferably a resin having a carbon chain as the main chain. The carbon chain may be formed by radical polymerization of an ethylenically unsaturated group. The fluororesin may be PVDF-HFP.

[0026] The polymer may contain at least one of a structural unit having the anionic functional group and an alkali metal ion as a counter cation of the anionic functional group (hereinafter also referred to as structural unit (A)), and a structural unit having a functional group that functions as an anion receptor (hereinafter also referred to as structural unit (B)). The polymer may contain one or more types of structural unit (A). The polymer may also contain one or more types of structural unit (B).

[0027] The polymer may contain, as the alkali metalated group, one or more groups selected from the group consisting of an alkali metalated sulfonylimide group, an alkali metalated sulfonic acid group, an alkali metalated carboxylic acid group, and an alkali metalated phenolic hydroxyl group.

[0028] Here, the term "alkali metalated group" as used herein refers to a group in which an anionic functional group, which is a conjugate base of the acid form of the group, forms a salt with an alkali metal ion. Specific examples of the alkali metalated group include an alkali metalated sulfonylimide group, an alkali metalated sulfonic acid group, an alkali metalated carboxylic acid group, and an alkali metalated phenolic hydroxyl group.

[0029] The alkali metal sulfonylimide group is a sulfonylimide acid group (-SO ２ -NH-SO ２ - group) in which H is substituted with an alkali metal element A ２ -NA-SO ２ - group ([-SO ２ -N-SO ２ -] － A ＋ The alkali metal sulfonic acid group refers to a sulfonic acid group (—SO ３ H group) in which H is replaced by an alkali metal element A. ３ A group ([-SO ３ ] － A ＋ The alkali metal carboxylic acid group refers to a —COOA group ([—COO] group) in which H of a carboxylic acid group (—COOH group) is substituted with an alkali metal element A. － A ＋ The alkali metal phenolic hydroxyl group refers to an —OA group (—O group) in which the H of the —OH group, which is a phenolic hydroxyl group, is substituted with an alkali metal element A. － A ＋ This refers to the group.

[0030] The structure of the polymer is not particularly limited, but examples thereof include those having a carbon chain as the main chain, and the carbon chain may be formed by radical addition polymerization of a monomer having an ethylenically unsaturated group.

[0031] The alkali metal element A may include at least one selected from the group consisting of lithium, sodium, potassium, rubidium, and cesium, may include at least one selected from the group consisting of lithium, sodium, and potassium, may include at least one of lithium and sodium, may include lithium, or may be lithium.

[0032] The content of one alkali metal element among the alkali metal elements contained in the polymer may be 80 mol% or more, 85 mol% or more, or 90 mol% or more. The one alkali metal element may be potassium, sodium, or lithium, or may be sodium or lithium.

[0033] The structural unit (A) may contain at least one of a structural unit represented by the following formula (A1) and a structural unit represented by the following formula (A2). (In formula (A1), Y is a monovalent group converted to an alkali metal. R １ ~R ３ are each independently a hydrogen atom or a monovalent substituent, or R １ and R ２ One of them is R ３ and form a ring together, and the other is a hydrogen atom or a monovalent substituent. １ ~R ３ may have the above-mentioned alkali metalated group. (In formula (A2), Z is a divalent group converted to an alkali metal. R ４ and R ５ are each independently a hydrogen atom or a monovalent substituent, or R ４ and R ５ are joined together to form a ring. ４ and R ５ may have the above-mentioned alkali metalated group.

[0034] In addition, in formula (A1), R １ ~R ３ and Y are omitted, and in formula (A2), R ４ , R ５The structure excluding Z is also simply called an ethylene unit.

[0035] In formula (A1), Y may contain one or more groups selected from the group consisting of an alkali metal substituted sulfonylimide group, an alkali metal substituted sulfonic acid group, an alkali metal substituted carboxylic acid group, and an alkali metal substituted phenolic hydroxyl group, or may contain one or more groups selected from the group consisting of an alkali metal substituted sulfonic acid group, an alkali metal substituted carboxylic acid group, and an alkali metal substituted phenolic hydroxyl group. One or more functional groups may be used as Y.

[0036] In formula (A1), R １ ~R ３ The monovalent substituent as R may be a monovalent organic group. １ ~R ３ When R is a monovalent substituent, the substituent may be a monovalent organic group. The number of carbon atoms in the monovalent organic group may be, for example, 1 to 20, 1 to 15, 1 to 10, 1 to 5, or 1 to 3. １ ~R ３ At least one of the groups may be a hydrogen atom, or all of the groups may be hydrogen atoms. Examples of the monovalent organic group include a methyl group.

[0037] In formula (A1), R １ and R ２ One of them is R ３ When R forms a ring together with １ or R ２ and R ３ In formula (A2), R forms a divalent substituent bonded to two carbon atoms of the ethylene unit of formula (A1). ４ and R ５ are taken together to form a ring, R ４ and R ５ form divalent substituents bonded to two carbon atoms of the ethylene unit of formula (A2), respectively. These rings may be either carbocyclic or heterocyclic. The number of ring members of these rings may be, for example, 4 to 10, 5 to 8, 5, or 6. A substituent may be bonded to the carbon atom or heteroatom that is a ring member.

[0038] In formula (A1), when Y contains an alkali metal-modified carboxylic acid group (-COOA group, A is an alkali metal), Y may be the -COOA group itself, or may be a monovalent organic group having a -COOA group. When Y is a monovalent organic group, the number of carbon atoms contained in the organic group may be, for example, 1 to 20, 1 to 15, 1 to 10, 1 to 5, or 1 to 3. The monovalent organic group may have one or more -COOA groups, or may have one -COOA group. In addition to the -COOA group, Y may have an electron-withdrawing group such as a halogen atom.

[0039] In formula (A1), Y is -R ９ -COOA, where R ９ is a divalent organic group or a covalent bond. The number of carbon atoms in the divalent organic group may be, for example, 1 to 19, 1 to 14, 1 to 9, 1 to 4, or 1 or 2.

[0040] In formula (A1), when Y has an alkali metal-substituted phenolic hydroxyl group, Y may be a group having one or more -OA groups (A is an alkali metal element) directly bonded to a carbon atom that is a member of an aromatic ring such as a benzene ring, a naphthalene ring, or an anthracene ring. Another ring structure may be condensed with the aromatic ring. For example, Y may have a group represented by any of the following formulas (A21) to (A26). Y may be directly covalently bonded to a carbon atom of the ethylene unit in formula (A1), or may be bonded via a linking group (for example, a divalent linking group). (In formula (A21), R Ａ１ ~R Ａ５ At least one of the groups is an -OA group, and the rest are hydrogen atoms or monovalent substituents. Ａ３ The group may be an —OA group. Ａ２ and R Ａ４ or R Ａ１ , R Ａ２ , R Ａ４ , and R Ａ５each independently represents a hydrogen atom, an —OA group, a methyl group, an ethyl group, or a monovalent organic group having 1 to 20 carbon atoms (provided that when the monovalent organic group is a saturated hydrocarbon group, it is a methyl group, an ethyl group, or a group having 6 to 20 or 6 to 15 carbon atoms, and when the monovalent organic group is an alkoxy group, it is a group having 4 to 20 or 4 to 15 carbon atoms). In formula (A22), R Ｂ１～ R Ｂ７ At least one of the groups is an -OA group, and the rest are hydrogen atoms or monovalent substituents. Ｂ３ ~R Ｂ６ At least one of the groups may be an —OA group. Ｃ１～ R Ｃ９ At least one of the groups is an -OA group, and the rest are hydrogen atoms or monovalent substituents. Ｃ２ ~R Ｃ８ At least one of the groups may be an —OA group. Ｄ１～ R Ｄ６ At least one of the groups is an -OA group, and the rest are hydrogen atoms or monovalent substituents. Ｄ３～ R Ｄ６ At least one of the groups may be an —OA group. Ｅ１～ R Ｅ９ At least one of the groups is an -OA group, and the rest are hydrogen atoms or monovalent substituents. Ｅ２ ~R Ｅ８ At least one of the groups may be an —OA group. Ｆ１～ R Ｆ９ At least one of the groups is an -OA group, and the rest are hydrogen atoms or monovalent substituents. Ｆ１～ R Ｆ９ At least one of the groups may be an —OA group.

[0041] The groups represented by formulae (A21) to (A26) may have 1 to 3 -OA groups, may have 1 or 2 -OA groups, or may have 1 -OA group.

[0042] In formulas (A21) to (A26), the monovalent substituent is preferably an electron-withdrawing group. Examples of the electron-withdrawing group include a halogen atom, a sulfonic acid group or a salt thereof, a sulfonic acid ester, a nitro group, and a nitrile group. The halogen atom may be any of F, Cl, Br, and I.

[0043] In addition, in formulae (A21) to (A26), the monovalent substituent may be an organic group having 1 to 20 carbon atoms. The number of carbon atoms in the organic group may be, for example, 1 to 15, 1 to 10, 1 to 5, or 1 to 3.

[0044] In the formula (A1), when Y is a sulfonic acid group modified with an alkali metal, examples of Y include groups represented by the following formula (A3). (In formula (A3), R １９ is a covalent bond or a divalent organic group. A is an alkali metal element.

[0045] In formula (A3), the divalent organic group may have, for example, 1 to 20, 1 to 15, 1 to 10, 1 to 5, or 1 to 3 carbon atoms.

[0046] The alkali metal sulfonic acid group is —SO ３ A, -CH ２ -SO ３ A, -C ６ H ４ -SO ３ Examples include A.

[0047] The structural unit (A2) may be a group containing a maleimide ring having an alkali metal-substituted group, and examples of the structural unit (A2) include the following structural unit (A4). (In formula (A4), X is a divalent organic group having 1 to 20 carbon atoms, and Y １ is a halogen atom or a monovalent organic group having 1 to 20 carbon atoms, and A ＋ represents an alkali metal ion, and * represents the position where the structural unit (A4) is bonded to another structural unit.

[0048] In formula (A4), the number of carbon atoms that X has may be, for example, 1 to 15, 2 to 10, or 3 to 8.

[0049] In formula (A4), the hydrocarbon group represented by X may be a phenylene group, an alkylene group having 1 to 8 carbon atoms, a polyoxyalkylene group, or a group in which some or all of the hydrogen atoms bonded to the carbon atoms of these groups have been substituted with halogen atoms such as fluorine atoms, or a divalent group having a substituted or unsubstituted phenylene group, or a phenylene group or substituted phenylene group. The substituted phenylene group refers to a functional group in which at least some of the hydrogen atoms constituting the phenylene group have been substituted with an alkyl group, a halogen atom, an electron-withdrawing group, or the like.

[0050] In formula (A4), Y １ is a monovalent organic group, Y １ The number of carbon atoms contained in Y may be, for example, 1 to 15, 1 to 10, 1 to 8, 1 to 5, or 1 to 3. １ The hydrocarbon group as Y may be a phenyl group, an alkyl group having 1 to 5 carbon atoms, or a group in which some or all of the hydrogen atoms bonded to the carbon atoms of these groups have been substituted with halogen atoms such as fluorine atoms, or may be a fluorinated alkyl group having 1 to 5 carbon atoms, or a fluorinated alkyl group having 1 to 3 carbon atoms such as a trifluoromethyl group. The fluorinated alkyl group may be a perfluorinated alkyl group. １ When is a halogen atom, the halogen atom may be a fluorine atom or a chlorine atom, and may be a fluorine atom.

[0051] The structural unit (B) functions as an anion receptor, which is a chemical species that captures anions by forming electrostatic interactions, hydrogen bonds, acid-base complexes, or the like with anions.

[0052] The structural unit (B) captures the counter anion of the alkali metal ion in the alkali metal salt and promotes dissociation of the counter anion from the alkali metal ion. This increases the mobility of the alkali metal ion. Meanwhile, the counter anion is captured by the polymer via the structural unit (B), decreasing the mobility of the counter anion. As a result, it is believed that the transport number of the alkali metal ion is improved. Furthermore, since the mobility of the alkali metal ion is increased, the conductivity of the alkali metal ion also tends to improve. Low-molecular-weight chemical species (compounds, etc.) that function as anion receptors are known, and examples of such compounds include those described in U.S. Patent Nos. 6,022,643, 5,705,689, and 6,120,941.

[0053] The functional group functioning as an anion receptor may have Lewis acidity. In this case, the functional group can capture the anion by accepting the unshared electron pair of the anion and forming an acid-base complex. Examples of such functional groups include functional groups having an electron-deficient atom. Note that an electron-deficient atom refers to an atom that is covalently bonded to another atom but the electrons in the outermost shell of the atom do not form an octet. Examples of electron-deficient atoms include atoms belonging to Group 13 of the periodic table, and more specifically, may be at least one of aluminum and boron, or may be boron.

[0054] The functional group having a function as an anion receptor may be a group having an azaether moiety. The group having an azaether moiety is a group having an azaether compound as a substituent, and the azaether compound is formed by replacing —O— of an ether compound with —NR Ｅ - (where R Ｅ is a hydrogen atom or an organic group). The azaether moiety may be either a linear azaether moiety or a cyclic azaether moiety, or may have both a linear azaether moiety and a cyclic azaether moiety. The group having an azaether moiety may have an electron-withdrawing group, for example, in the hydrocarbon moiety.

[0055] The structural unit (B) may contain at least one structural unit represented by the following formula (B). (In formula (B), W is a functional group having a function as an anion receptor, and R １１ ~R １３ are each independently a hydrogen atom or a monovalent substituent, or R １１ and R １３ One of them is R １２ and form a ring together, and the other is a hydrogen atom or a monovalent substituent. * indicates the position where the structural unit (B) is bonded to another structural unit. R １１ ~R １３ may be hydrogen atoms, or all of may be hydrogen atoms.)

[0056] In addition, in formula (B), R １１ ~R １３ The structure excluding W is also simply called an ethylene unit.

[0057] In formula (B), R １１ ~R １３ is a monovalent substituent, the monovalent substituent may be a monovalent organic group. The number of carbon atoms in the organic group may be, for example, 1 to 20, 1 to 15, 1 to 10, 1 to 5, or 1 to 3.

[0058] The monovalent substituent may have an electron-withdrawing group or may be the electron-withdrawing group itself. The electron-withdrawing group may be bonded to the monovalent organic group, or the monovalent organic group may be the electron-withdrawing group. Examples of the electron-withdrawing group include a halogen atom, a sulfonic acid group or a salt thereof, a sulfonic acid ester, a nitro group, and a nitrile group. The halogen atom may be a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom.

[0059] In formula (B), R １１ and R １３ One of them is R １２ When R forms a ring together with １１ or R １２ and R １３form divalent substituents bonded to two carbon atoms of the ethylene unit of formula (B), respectively. These rings may be either carbocyclic or heterocyclic. The number of ring members of these rings may be, for example, 4 to 10, 5 to 8, 5, or 6. A substituent may be bonded to the carbon atom or heteroatom that is a ring member.

[0060] In formula (B), W preferably has a group represented by formula (B1) below. (In formula (B1), W Ｂ is an atom belonging to group 13 of the periodic table, and R １５ is a covalent bond or a divalent organic group, and R １６ and R １７ are each independently a hydrogen atom, an —OH group, a halogen atom, or a monovalent organic group, or are joined together to form a ring. １６ and R １７ may be the same group or different groups.)

[0061] W Ｂ may be at least one of an aluminum atom and a boron atom, and may be a boron atom.

[0062] In formula (B1), R １５ When R is a divalent organic group, the number of carbon atoms in the divalent organic group may be, for example, 1 to 20, 1 to 15, 1 to 10, 1 to 5, or 1 to 3. １５ is a hydrocarbon group, a halogen-substituted hydrocarbon group, or a hydrocarbon group or a halogen-substituted hydrocarbon group connected to W via an ether bond Ｂ The halogen-substituted hydrocarbon group may be a hydrocarbon group in which some or all of the hydrogen atoms have been substituted with halogen atoms, and may be a partially fluorinated hydrocarbon group or a fully fluorinated hydrocarbon group. １５ may be a covalent bond.

[0063] In formula (B1), R １６ or R １７ is a halogen atom, R １６ or R １７may be any of a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, and may also be a fluorine atom.

[0064] In formula (B1), R １６ or R １７ When R is a monovalent organic group, the number of carbon atoms in the monovalent organic group may be, for example, 1 to 20, 1 to 15, 1 to 10, 1 to 5, or 1 to 3. ６ or R ７ is a hydrocarbon group, a halogen-substituted hydrocarbon group, or a hydrocarbon group or a halogen-substituted hydrocarbon group connected to W via an ether bond Ｂ The halogen-substituted hydrocarbon group may be a hydrocarbon group in which some or all of the hydrogen atoms have been substituted with halogen atoms, and may be a partially fluorinated hydrocarbon group or a fully fluorinated hydrocarbon group.

[0065] The group represented by formula (B1) may be a group represented by the following formula (B1a) or a group represented by the following formula (B1b). (In formula (B1a), R １５ is a covalent bond or a divalent organic group, and X １１ and X １２ are each independently an oxygen atom or a covalent bond. １１ is a covalent bond, R ２１ is a hydrogen atom, a halogen atom, or a monovalent organic group. １１ is an oxygen atom, R ２１ is a hydrogen atom or a monovalent organic group. １２ is a covalent bond, R ２２ is a hydrogen atom, a halogen atom, or a monovalent organic group. １２ is an oxygen atom, R ２２ is a hydrogen atom, a halogen atom, or a monovalent organic group. １１ and X １２ When each is an oxygen atom, they may be oxygen atoms that form an ether bond. (In formula (B1b), R １５ is a covalent bond or a divalent organic group, and X １３ and X １４ are each an oxygen atom or a covalent bond, and R２３ is a divalent organic group.

[0066] In formula (B1a), R ２１ Or R ２２ When R is a monovalent organic group, the monovalent organic group may be a monovalent hydrocarbon group or a monovalent halogen-substituted hydrocarbon group. The number of carbon atoms in the monovalent organic group may be, for example, 1 to 20, 1 to 15, 1 to 10, 1 to 5, or 1 to 3. The halogen-substituted hydrocarbon group may be a hydrocarbon group in which some or all of the hydrogen atoms have been substituted with halogen atoms, and may be a partially fluorinated hydrocarbon group or a fully fluorinated hydrocarbon group. In formula (B1a), R ２１ Or R ２２ When is a halogen atom, the halogen atom may be a fluorine atom.

[0067] In formula (B1a), R ２１ and R ２２ are each independently —F, —CH ３ , -C ２ H ５ , -C ３ H ７ , -C ６ H ５ (phenyl group), —C ６ H ｎ F ５－ｎ (n is an integer of 0 to 4, and may be an integer of 0 to 3), -CF ３ , -CH ２ CF ３ , -CH ２ CF ３ CF ７ , -CH(CF ３ ) ２ , -C(CF ３ ) ２ -C ６ H ５ , -C(CF ３ ) ３ , -C ６ H ｎ (CF ３ ) ５－ｎ (n is an integer from 0 to 4, and may be 1 or 2.)

[0068] In formula (B1b), the divalent organic group may have, for example, 1 to 20, 1 to 15, 2 to 10, or 3 to 8 carbon atoms. The divalent organic group may be a hydrocarbon group or a halogen-substituted hydrocarbon group. The halogen-substituted hydrocarbon group may be a hydrocarbon group in which some or all of the hydrogen atoms have been substituted with halogen atoms, and may be a partially fluorinated hydrocarbon group or a fully fluorinated hydrocarbon group.

[0069] In formula (B1a), R ２３ is -C ２ H ４ -, -C ３ H ６ -, -C ４ H ８ -, -C ５ H １０ -, -C ６ H １２ -, -C ７ H １４ -, -C ８ H １６ -, -C ９ H １８ -, -C １０ H ２０ -, etc., or compounds in which the hydrogen atoms of these groups are partially or entirely substituted with fluorine atoms. More specifically, R ２３ is -C(CH ３ ) ２ -C(CH ３ ) ２ - may be.

[0070] The polymer may contain a structural unit (C) that is neither the structural unit (A) nor the structural unit (B). The structural unit (C) may contain a structural unit (C) represented by the following formula (C): (In formula (C), R ２５ is a hydrogen atom or a monovalent substituent, and R ２６ ~R ２８ are each independently a hydrogen atom or a monovalent substituent, or R ２６ and R ２７ is a hydrogen atom or a monovalent substituent, and the other is R ２８ and form a ring. * indicates the bonding site of the structural unit (C) to other structural units.

[0071] In formula (C), R ２５ may be a monovalent organic group. The monovalent organic group is -Z １ -R ２９ R ２５ may have, for example, 1 to 40 carbon atoms, 1 to 20 carbon atoms, 2 to 15 carbon atoms, or 4 to 13 carbon atoms. １ is a divalent linking group, for example, a covalent bond, —O—, —S—, —C(═O)—, —C(═O)O—, —OC(═O)—, or —C(═O)NR ３８ -or-NR ３９ It may be a group represented by C(=O)-.

[0072] Above Z １ is a covalent bond, —O—, —S—, —C(═O)—, —C(═O)O—, or —OC(═O)—, R ２９ is a hydrogen atom or a monovalent organic group. １ -C(=O)NR ３８ -, then R ２９ , R ３８ are each a hydrogen atom or a monovalent organic group, or R ２９ is R ３８ It forms a ring together with -NR ３９ When C(=O)-, R ２９ , R ３９ are each a hydrogen atom or a monovalent organic group, or R ２９ is R ３９ The above Z forms a ring together with １ But, R ２９ , R ３８ and R ３９ The monovalent organic group as R may have 1 to 20 organic groups, or 1 to 10 organic groups. ３８ When is a monovalent organic group, it may be a monovalent hydrocarbon group having 1 to 20 carbon atoms.

[0073] Above Z １ is a covalent bond or —C(═O)O—, R ２９ may be a hydrogen atom or a monovalent hydrocarbon group having 1 to 20 carbon atoms. １ is a covalent bond and R ２９When R is a hydrocarbon group, the hydrocarbon group may be an aliphatic hydrocarbon group. ２９ may be a monovalent organic group other than a hydrocarbon group or a hydrocarbon group having a ring structure.

[0074] Above Z １ When R is —O—, it may be a monovalent organic group other than the group represented by W—H when W is an alkyl ether. ２６ ~R ２８ When R is a monovalent organic group, the monovalent organic group is ２５ Examples of the monovalent organic group include the same as those given above. The monovalent organic group may be a group having an aromatic ring.

[0075] In the group having an aromatic ring, a monovalent substituent may be bonded to the aromatic ring. Examples of the monovalent substituent include a monovalent organic group, and examples of the monovalent organic group include a substituted or unsubstituted hydrocarbon group, a group represented by the formula: -R ４１ - (W １ -R ４２ ) n-W ２ R ４３ Examples include groups represented by the formula: -R ４１ - (W １ -R ４２ ) ｎ -W ２ R ４３ The group represented by the formula (I) may be bonded to the para position of the benzene ring. １ may be a divalent group such as -O-, -S-, -C(=O)- or -C(=O)O-, or may be -O-. ２ may be a divalent group such as —O—, —S—, —C(═O)— or —C(═O)O—, or may be —O—.

[0076] The above R ４１is a covalent bond or a divalent organic group. The divalent organic group may be a divalent hydrocarbon group. The divalent hydrocarbon group may have, for example, 1 to 8, 1 to 5, or 1 to 3 carbon atoms. The hydrogen atoms bonded to the divalent hydrocarbon group may be substituted with a substituent such as a monovalent substituent (i.e., the divalent hydrocarbon group may be a substituted hydrocarbon group). Examples of the substituent include a halogen atom such as a fluorine atom. The divalent hydrocarbon group may be either an aromatic hydrocarbon group or an aliphatic hydrocarbon group, and may be an aliphatic hydrocarbon group. The aliphatic hydrocarbon group may be a saturated aliphatic hydrocarbon group, or may be a linear or branched aliphatic hydrocarbon group. Specific examples of the divalent hydrocarbon group include a methylene group, an ethylene group, a 1,2-propylene group, a 1,3-propylene group, or a group in which some or all of the hydrogen atoms of these groups have been substituted with halogen atoms such as fluorine atoms, and may be a methylene group.

[0077] The above R ４２ is a divalent organic group and may be a divalent hydrocarbon group. The divalent hydrocarbon group may have, for example, 1 to 8, 1 to 5, or 1 to 3 carbon atoms. The hydrogen atoms bonded to the divalent hydrocarbon group may be substituted with a substituent such as a monovalent substituent (i.e., the divalent hydrocarbon group may be a substituted hydrocarbon group). Examples of the substituent include a halogen atom such as a fluorine atom. The divalent hydrocarbon group may be either an aromatic hydrocarbon group or an aliphatic hydrocarbon group, and may be an aliphatic hydrocarbon group. The aliphatic hydrocarbon group may be a saturated aliphatic hydrocarbon group, and may be a linear or branched aliphatic hydrocarbon group. Specific examples of the divalent hydrocarbon group include a methylene group, an ethylene group, a 1,2-propylene group, a 1,3-propylene group, or a group in which some or all of the hydrogen atoms of these groups have been substituted with halogen atoms such as fluorine atoms, and may be an ethylene group. n may be, for example, 1 to 10, 1 to 5, or 1 to 3. n may be an integer or a rational number (for example, n is an average value across the structural units (B) contained in the polymer). ４２ When there are multiple, they may be different or the same.

[0078] The above R ４３ may be a hydrogen atom or a divalent hydrocarbon group. The number of carbon atoms in the monovalent hydrocarbon group may be, for example, 1 to 8, 1 to 5, or 1 to 3. The hydrogen atom bonded to the monovalent hydrocarbon group may be substituted with a substituent such as a monovalent substituent (i.e., the monovalent hydrocarbon group may be a substituted hydrocarbon group). Examples of the substituent include a halogen atom such as a fluorine atom. The monovalent hydrocarbon group may be either an aromatic hydrocarbon group or an aliphatic hydrocarbon group, and may be an aliphatic hydrocarbon group. The aliphatic hydrocarbon group may be a saturated aliphatic hydrocarbon group, and may be a linear or branched aliphatic hydrocarbon group. Specific examples of the divalent hydrocarbon group include a methyl group, an ethyl group, an isopropyl group, an n-propyl group, or a group in which some or all of the hydrogen atoms in these groups have been substituted with halogen atoms such as fluorine atoms, and may be a methyl group.

[0079] The structural unit (C) may contain at least one structural unit derived from a monomer represented by the following formula (C1). (wherein m is 0 to 4 and n is 0 to 10. R ２０ may be a hydrogen atom or an alkyl group having 1 to 4 carbon atoms. The alkyl group may be a methyl group or an ethyl group, or may be a methyl group.

[0080] In formula (C1), m may be, for example, 1 to 3, 1 to 2, or 1. m may be an integer or an average value across all structural units derived from the monomer represented by formula (C1) contained in the polymer (in this case, m is a rational number). In formula (C1), n ​​may be, for example, 1 to 4, or 1 to 3. n may be an integer or an average value across all structural units derived from the monomer represented by formula (C1) contained in the polymer (in this case, n is a rational number).

[0081] The above R ２６ and R ２７ One of them is R ２８ When the structural unit (C) forms a ring together with the structural unit (C), the ring may have, for example, 4 to 10, 4 to 8, or 5 to 7 ring members. The structural unit (C) may be the following structural unit (C2). (In formula (C2), X represents an oxygen atom or —NR ２４ - is a tertiary amino group represented by R ２４ is a monovalent organic group, and R ２５ and R ２６ are each independently a hydrogen atom or a monovalent substituent.

[0082] The above R ２４ The number of carbon atoms contained in R may be, for example, 1 to 20, 1 to 15, or 2 to 10. ２４ may be a hydrocarbon group or a hydrocarbon group substituted with fluorine, and may be an ethyl group, a 2,2,2-trifluoroethyl group, an n-dodecyl group, a cyclohexyl group, or a benzyl group.

[0083] The ratio of the structural unit (A) to all structural units contained in the polymer may be, for example, 0.2 to 0.95, 0.2 to 0.8, 0.3 to 0.7, or 0.4 to 0.6.

[0084] The ratio of the structural unit (C) to all structural units contained in the polymer may be, for example, 0.05 to 0.8, 0.2 to 0.8, 0.3 to 0.7, or 0.4 to 0.6. The ratio of the structural unit (C) to all structural units contained in the polymer may be, for example, 0.8 or less, 0.7 or less, 0.6 or less, or 0.3 or less.

[0085] The total proportion of the structural units (A) and (C) relative to all structural units contained in the polymer may be, for example, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.9 or more, or 0.95 or more. The total proportion of the structural units (A) and (C) relative to all structural units contained in the polymer may be, for example, less than 1.0, or 0.97 or less. The total proportion of the structural units (A) and (C) relative to all structural units contained in the polymer may be, for example, 0.5 or more and less than 1.0, or 0.5 to 0.97.

[0086] The content of the structural unit (A) relative to the total mass of the polymer may be, for example, 25 to 95 mass %, 40 to 90 mass %, or 50 to 90 mass %.

[0087] The content of the structural unit (C) relative to the total mass of the polymer may be, for example, 5 to 75 mass%, 10 to 60 mass%, or 10 to 50 mass%, and the content of the structural unit (C) relative to the total mass of the polymer may be, for example, 75 mass% or less, 60 mass% or less, 50 mass% or less, or 25 mass% or less.

[0088] The total content of the structural unit (A) and the structural unit (C) relative to the total mass of the polymer may be, for example, 90 mass % or more, 95 mass % or more, or 98 mass % or more.

[0089] When the polymer contains the structural unit (B), the molar ratio m of the structural unit (B) to all structural units contained in the polymer may be, for example, 0.2 to 0.8, 0.25 to 0.75, 0.3 to 0.7, 0.35 to 0.65, or 0.4 to 0.6. The content of the structural unit (B) relative to the total mass of the polymer may be, for example, greater than 10% by mass and 95% by mass or less, 15 to 95% by mass, 20 to 80% by mass, 25 to 60% by mass, or 30 to 45% by mass.

[0090] The number average molecular weight (Mn) of the polymer may be, for example, 5,000 to 400,000, 8,000 to 200,000, 10,000 to 150,000, or 10,000 to 100,000. The weight average molecular weight (Mw) of the polymer may be, for example, 5,000 to 600,000, 10,000 to 450,000, 20,000 to 200,000, or 20,000 to 100,000. The molecular weight distribution (Mw / Mn) of the polymer may be, for example, 1.0 to 5.0, 1.2 to 3.0, or 1.3 to 2.5. The number average molecular weight and weight average molecular weight of the polymer can be measured, for example, by gel permeation chromatography.

[0091] There is no particular limitation on the method for producing a polymer capable of preferentially conducting alkali metal ions. For example, it can be produced by subjecting a corresponding monomer to radical addition polymerization.

[0092] <Positive Electrode> The positive electrode in the battery of this embodiment contains a positive electrode active material and a polymer capable of preferentially conducting alkali metal ions, and has a porosity of 23% or more at 0.1 to 100 μm as measured by mercury porosimetry. The positive electrode in the battery of this embodiment may also contain a positive electrode active material, a polymer capable of preferentially conducting alkali metal ions, and a conductive additive containing a nanocarbon material. Examples of nanocarbon materials include fullerene, graphene, and carbon nanotubes. In the present disclosure, the "porosity at 0.1 to 100 μm as measured by mercury porosimetry" refers to the percentage (%) of the total volume of pores having a pore size (diameter) of 0.1 to 100 μm relative to the total volume of the object being measured.

[0093] The carbon nanotubes may be either single-walled or multi-walled, or may be multi-walled. The average length of the carbon nanotubes may be, for example, 1 μm or more, or 5 μm or more, and may be 10,000 μm or less, or 5,000 μm or less. The conductivity of the carbon nanotubes may be metallic. The average diameter of the carbon nanotubes may be, for example, 0.4 nm to 100 nm, 0.5 to 50 nm, or 1 to 30 nm.

[0094] The BET specific surface area of ​​carbon nanotubes is, for example, 400 m ２ The carbon nanotube may have a ratio of the G band intensity to the D band intensity (G / D ratio) in Raman spectrum analysis obtained by Raman spectroscopy of, for example, 10 or less. The tensile strength of the carbon nanotube may be, for example, 50 to 70 MPa.

[0095] The content of the polymer capable of preferentially conducting alkali metal ions in the positive electrode may be, for example, 0.01 to 20 mass %, 0.05 to 15 mass %, 0.1 to 10 mass %, 0.5 to 8 mass %, or 1 to 5 mass % relative to the total mass of the positive electrode.

[0096] The porosity of the positive electrode may be, for example, 23 to 50%, 23 to 40%, 24 to 35%, or 24 to 30%. Methods for adjusting the porosity include adding a fibrous carbon material such as vapor-grown carbon fiber (VGCF) to the conductive additive to suppress aggregation between the polymer and the conductive additive, or first mixing the polymer and the positive electrode active material and then adding the conductive additive. The method of adding the conductive additive later is effective for increasing the porosity when adding a powdered conductive additive such as acetylene black.

[0097] The positive electrode active material is not particularly limited, and examples thereof include a lithium composite metal oxide containing lithium and at least one metal element selected from the group consisting of a transition metal element and Al. The transition metal element may be at least one element selected from the group consisting of V, Cr, Mn, Fe, Co, Ni, and Cu, and may include Ni.

[0098] Examples of lithium composite metal oxides include LiCoO ２ , LiNiO ２ , LiMn ２ O ４ , LiNi ０．５ Mn １．５ O ４ , Li ２ MnO ３ , LiNi ｘ Mn ｙ Co １－ｘ－ｙ O ２ [0<x+y<1]), LiNi ｘ Co ｙ Al １－ｘ－ｙ O ２ [0<x+y<1]), LiCr ０．５ Mn ０．５ O ２ , LiFePO ４ , Li ２ FeP ２ O ７ , LiMnPO ４ , LiFeBO ３ , Li ３ V ２ (P.O. ４ ) ３ , Li ２ CuO ２ , Li ２ FeSiO４ , Li ２ MnSiO ４ When the positive electrode active material contains an alkali metal element other than Li, specific examples thereof include those in which Li in the above specific examples is replaced with another alkali metal.

[0099] The content of the positive electrode active material in the positive electrode may be, for example, 70 mass % or more, 80 to 99 mass %, 85 to 97 mass %, 87 to 96 mass %, or 90 to 95 mass % relative to the total mass of the positive electrode.

[0100] The positive electrode may further contain a conductive additive, a binder resin, etc. The binder resin is not particularly limited, but examples thereof include fluororesins and synthetic rubbers. The fluororesins are preferably resins having a carbon chain as the main chain. The carbon chain may be formed by radical polymerization of an ethylenically unsaturated group. Examples of fluororesins include poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and polyvinylidene fluoride (PVDF). Examples of synthetic rubber include SBR (styrene butadiene rubber).

[0101] The content of the binder resin in the positive electrode may be, for example, 0.01 to 10 mass %, 0.1 to 7 mass %, or 0.5 to 5 mass % relative to the total mass of the positive electrode.

[0102] Examples of the conductive aid include graphites such as natural graphite (e.g., flake graphite) and artificial graphite; carbon blacks such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; carbon fibers such as vapor-grown carbon fiber (VGCF); and carbon materials such as the above-mentioned nanocarbon materials.

[0103] The content of the conductive additive in the electrode material may be, for example, 0.01 to 10 mass %, 0.05 to 8 mass %, 0.05 to 5 mass %, 0.5 to 3 mass %, 0.1 to 1 mass %, or 0.1 to 0.8 mass %.

[0104] <Electrolyte> The electrolyte is a membrane containing the polymer capable of preferentially conducting alkali metal ions, and in the electrolyte, the polymer capable of preferentially conducting alkali metal ions is swollen with a solution containing a film-forming additive and an organic solvent. The electrolyte may further contain an alkali metal salt, an anion receptor, etc. Examples of the polymer capable of preferentially conducting alkali metal ions contained in the electrolyte include the same polymers as those contained in the positive electrode described above.

[0105] The electrolyte is formed from an electrolyte composition that includes a polymer capable of preferentially conducting alkali metal ions, a film-forming additive, and an organic solvent, with the polymer swollen by the organic solvent.

[0106] The content of the polymer capable of preferentially conducting alkali metal ions in the electrolyte composition may be, for example, 1 to 80 mass %, 3 to 70 mass %, 5 to 60 mass %, 8 to 50 mass %, or 10 to 40 mass % relative to the total amount of the electrolyte composition.

[0107] The film-forming additive contained in the electrolyte composition of this embodiment is a compound that can form a film (solid electrolyte interface, SEI) on the electrode surface by an electrolytic reaction. Therefore, the film-forming additive may be an SEI-forming agent. The film-forming additive may be at least one of an electrolytic oxidation-polymerizable compound and an electrolytic reduction-polymerizable compound, but may also be an electrolytic reduction-polymerizable compound. By using an electrolytic reduction-polymerizable compound, a film can be formed on the negative electrode.

[0108] Examples of the film-forming additive include aliphatic polyunsaturated compounds, aromatic compounds having a vinyl group, unsaturated ester compounds, unsaturated nitrile compounds, polyester compounds, vinyl ester compounds of carboxylic acids, cyclic acid anhydrides, cyclic imide compounds, phosphonate ester compounds, vinyl group-containing silane compounds, furan derivatives containing two double bonds in each molecule, sulfur-based compounds, organic nitro compounds, halogenated cyclic esters, nitrate ester compounds, nitrite ester compounds, aromatic ester compounds, aromatic isocyanate compounds, boron-based compounds, halogenated organic compounds, polydimethylsiloxane, electrolytically reductively polymerizable compounds such as silanes, etc. The electrolyte composition may contain one or more film-forming additives.

[0109] The film-forming additives also include electrolytically oxidatively polymerizable compounds such as pyrrole, aniline, thiophene, and derivatives thereof.

[0110] The film-forming additives include compounds that can be used as organic solvents. When the electrolyte composition of this embodiment contains a compound that can be used as both a film-forming additive and an organic solvent, it may further contain another compound as the organic solvent, or it may further contain another compound as the film-forming additive. In other words, the electrolyte composition of this embodiment may contain one or more compounds each as the organic solvent and the film-forming additive (i.e., a total of two or more compounds). Therefore, the solution containing the film-forming additive may be a mixed solvent of multiple film-forming additives.

[0111] The carbonate compound may be a cyclic carbonate compound or a chain carbonate compound. The carbonate compound may be a carbonate compound substituted with an ethylenically unsaturated group such as a vinyl group or a halogen atom such as a fluorine atom. Examples of the carbonate compound include ethylene carbonate, vinylene carbonate, vinylethylene carbonate, allyl ethyl carbonate, and fluoroethylene carbonate (4-fluoro-1,3-dioxane-2-one).

[0112] Examples of the aliphatic polyunsaturated compound include conjugated unsaturated compounds such as butadiene.

[0113] Examples of aromatic compounds having a vinyl group include vinylpyridines such as 2-vinylpyridine, methyl cinnamate, and styrene.

[0114] Examples of the unsaturated ester compound include (meth)acrylic acid esters and α-cyanoacrylic acid esters.

[0115] Examples of the unsaturated nitrile compound include α,β-unsaturated nitrile compounds such as (meth)acrylonitrile.

[0116] Examples of polyvalent ester compounds include dialkyl malonate compounds such as dimethyl malonate, diethyl malonate, di-n-hexyl malonate, and dicyclohexyl malonate.

[0117] Examples of vinyl ester compounds of carboxylic acids include vinyl acetate and divinyl adipate.

[0118] Examples of the cyclic acid anhydride include maleic anhydride.

[0119] Examples of the cyclic imide compound include compounds having a carbon-carbon unsaturated bond in the ring, such as maleimide, and compounds not having a carbon-carbon unsaturated bond in the ring, such as succinimide.

[0120] Examples of organic nitro compounds include nitro compounds having an ethylenically unsaturated group, such as nitroethylene (nitroethene).

[0121] Sulfur compounds include SO ２ (sulfur dioxide), polysulfides, sulfite ester compounds, sulfonate ester compounds, sulfate ester compounds, sulfone compounds, etc.

[0122] The sulfonate compound may be a cyclic sulfonate compound, and examples of the sulfonate include 1,3-propane sultone, 1,4-butane sultone, 1,3-propene sultone, and 1,4-butene sultone.

[0123] The sulfate ester compound may be a cyclic sulfate ester compound, and examples of the sulfate ester compound include propylene sulfate, butylene sulfate, and ethylene propyl sulfate.

[0124] Examples of sulfite compounds include cyclic alkyl sulfite compounds and aromatic (aryl) sulfite compounds. Examples of sulfite esters include ethylene sulfite and propylene sulfite. The sulfone compound may be a cyclic sulfone compound.

[0125] Examples of the sulfone compound include sulfolane, 3-methylsulfolane, 3-sulfolene, and 2-sulfolene.

[0126] Boron compounds include B ２ O ３ (boron oxide), organic boron compounds, boroxine compounds, etc.

[0127] The film-forming additive may include at least one of vinylene carbonate, fluoroethylene carbonate, ethylene carbonate (EC), vinyl ethylene carbonate (VEC), propane sultone (PS), ethylene sulfite (ES), γ-butyrolactone (GBL), lithium bis(oxalato)borate (LiBOB), and lithium difluoro(oxalato)borate (LiDFOB).

[0128] The content of the film-forming additive in the electrolyte composition may be, for example, 0.01 to 20 mass %, 0.05 to 15 mass %, 0.1 to 15 mass %, 0.5 to 10 mass %, or 1 to 5 mass % relative to the total amount of the electrolyte composition.

[0129] <Organic Solvent> The organic solvent may be an aprotic solvent. The organic solvent may include one or more organic solvents selected from the group consisting of carbonate-based solvents, ether-based solvents, fluorine-based solvents, nitrile-based solvents, lactone-based solvents, phosphate ester-based solvents, and sulfone-based solvents, and may include a phosphate ester. The organic solvent may include one or more solvents selected from the group consisting of carbonate-based solvents, ether-based solvents, fluorine-based solvents, nitrile-based solvents, and phosphate ester-based solvents, and may include a carbonate-based solvent. In the electrolyte composition, the polymer capable of preferentially conducting alkali metal ions may be swollen by the organic solvent.

[0130] Examples of carbonate solvents include chain carbonates such as dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate, and cyclic carbonates such as ethylene carbonate, propylene carbonate, butylene carbonate, and vinylene carbonate. The organic solvent may be a mixed solvent containing two or more carbonate solvents, such as a mixed solvent containing one or more cyclic carbonate solvents and one or more chain carbonate solvents, or a mixed solvent containing two or more cyclic carbonate solvents.

[0131] Examples of the ether solvent include cyclic ethers such as tetrahydrofuran, 2-methyltetrahydrofuran, tetrahydropyran, and 1,3-dioxolane; and chain ethers such as 1,2-diethoxyethane and ethoxymethoxyethane.

[0132] Examples of fluorine-based solvents include hydrofluorocarbons such as perfluorooctane; hydrofluoroethers such as methyl nonafluorobutyl ether and ethyl nonafluorobutyl ether; hydrofluoroolefins such as 1,3,3,3-tetrafluoropropene; and 2,2,2-trifluoro-N,N-dimethylacetamide.

[0133] Examples of the phosphate ester include trimethyl phosphate (TMP), triethyl phosphate (TEP), and tris(2,2,2-trifluoroethyl) phosphate (TFEP).

[0134] Examples of the nitrile solvent include acetonitrile, succinonitrile, etc. Examples of the lactone solvent include γ-butyrolactone, etc.

[0135] Other examples of organic solvents include sulfone solvents such as sulfolane and 3-methylsulfolane, solvents having a sulfonyl group such as dimethyl sulfoxide (DMSO), amide solvents such as dimethylformamide (DMF) and dimethylacetamide (DMA), organic solvents having a carbonyl group such as acetone (referring to carbonyl compounds other than amide compounds such as -C(=O)-, esters, ketones, and aldehydes), and nitrogen-containing aromatic compounds such as pyridine (compounds containing nitrogen as a ring member of the aromatic ring, which may be either monocyclic or fused ring systems). Only one organic solvent may be used, or a mixed solvent containing two or more organic solvents may be used.

[0136] The content of the organic solvent in the electrolyte composition may be, for example, 10 to 80 mass %, 20 to 75 mass %, 30 to 70 mass %, or 35 to 65 mass % relative to the total amount of the electrolyte composition.

[0137] The electrolyte composition may further contain other resins such as fluorine-based resins (resins other than polymers capable of preferentially conducting alkali metal ions, such as binder resins), fabrics such as nonwoven fabrics, porous materials, viscosity modifiers, anion receptors, etc. The electrolyte composition may contain, as the fluorine-based resin, a resin having a carbon chain as its main chain. The carbon chain may be formed by radical polymerization of an ethylenically unsaturated group. Examples of fluorine-based resins include poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and polyvinylidene fluoride (PVDF). The porous material may be a porous material made of resin. Specific examples include porous polyolefin membranes and porous ceramic membranes.

[0138] The content of the other resin may be, for example, 1 to 200 parts by mass, 5 to 150 parts by mass, 10 to 100 parts by mass, or 20 to 70 parts by mass relative to 100 parts by mass of the polymer capable of preferentially conducting alkali metal ions.

[0139] <Anion Receptor> The anion receptor is not particularly limited. The formula weight (molecular weight) of the anion receptor may be, for example, 1,000 or less, 800 or less, or 500 or less. The anion receptor may have Lewis acidity. In this case, the anion receptor can capture the anion by accepting the unshared electron pair of the anion and forming an acid-base complex. Examples of such compounds include compounds having an electron-deficient atom. Note that an electron-deficient atom refers to an atom that is covalently bonded to another atom but has fewer than eight electrons in its outermost shell. Examples of electron-deficient atoms include atoms belonging to Group 13 of the periodic table, and more specifically, may be at least one of an aluminum atom and a boron atom, or may be a boron atom.

[0140] Examples of anion receptors having a boron atom include boron compounds that function as Lewis acids, such as diborane and compounds represented by the following chemical formulas IA to IE.

[0141]

[0142] In Formulas IA and ID, R ３１ and R ３３ are each a halogen atom or a monovalent organic group. The halogen atom may be a fluorine atom or a chlorine atom, or may be a fluorine atom. The number of carbon atoms in the monovalent organic group may be, for example, 1 to 20, 1 to 15, 2 to 10, or 2 to 6. Here, the monovalent organic group is bonded to the boron atom (B) in formula IA or ID via a carbon atom in the monovalent organic group. The monovalent organic group may be a hydrocarbon group or a halogen-substituted hydrocarbon group, and the halogen-substituted hydrocarbon group may be a partially or fully fluorinated hydrocarbon group. In one molecule, multiple R ３１ and R ３３ may be different from each other or may all be the same.

[0143] In formulas IB and IE, R ３２ and R ３４are each a hydrogen atom or a monovalent organic group. The halogen atom may be a fluorine atom or a chlorine atom, or may be a fluorine atom. The number of carbon atoms in the monovalent organic group may be, for example, 1 to 20, 1 to 15, 2 to 10, or 2 to 6. Here, the monovalent organic group is bonded to the oxygen atom (O) in formula IB or IE via a carbon atom in the monovalent organic group. The monovalent organic group may be a hydrocarbon group or a halogen-substituted hydrocarbon group, and the halogen-substituted hydrocarbon group may be a partially or fully fluorinated hydrocarbon group. In one molecule, multiple R ３２ and R ３４ may be different from each other or may all be the same.

[0144] In formula IC, R ３５ is a divalent organic group, Z ２ is a covalent bond or an oxygen atom. The number of carbon atoms in the divalent organic group may be, for example, 1 to 15, 2 to 10, or 3 to 8. ３５ , two Zs ２ and the boron atom (B) form a ring, and the ring may have, for example, 4 to 8, 5, or 6 ring members. ２ When is an oxygen atom, the divalent organic group is connected to Z in formula IC by the carbon atom contained in the divalent organic group. ２ It is bonded to Z. ２ When Z is a covalent bond, the divalent organic group is bonded to the boron atom (B) in formula IC via a carbon atom contained in the divalent organic group. The divalent organic group may be a hydrocarbon group or a halogen-substituted hydrocarbon group, and the halogen-substituted hydrocarbon group may be a partially or fully fluorinated hydrocarbon group. In one molecule, multiple Z ２ may be different from each other or may all be the same.

[0145] In formula IC, R ３６ is a hydrogen atom or a monovalent organic group. The monovalent organic group may be a group that bonds to the boron atom (B) in formula IC via a carbon atom that the monovalent organic group has, but -OR ３７ R ３７is a hydrogen atom or a monovalent organic group. ３７ The monovalent organic group represented by the formula (I) is -OR ３７ It is bonded to the oxygen atom of R. ３６ or R ３７ The number of carbon atoms in the monovalent organic group may be, for example, 1 to 20, 1 to 15, 2 to 10, or 2 to 6. The monovalent organic group may be a hydrocarbon group or a halogen-substituted hydrocarbon group, and the halogen-substituted hydrocarbon group may be a partially or fully fluorinated hydrocarbon group.

[0146] Specific examples of boron compounds include diborane, boron trifluoride, boric acid, boroxine, trimethylborane, triethylborane, tri-n-propylborane, triisopropylborane, triphenylborane, trimethylborate, triethylborate, triphenylborate, tri-n-propylborate, triisopropylborate, 2-methoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane, and 2-ethoxy-4,4,5,5-tetramethyl-1,3,2-dioxaborolane. Examples thereof include organic boron compounds such as oran, 2,4,6-trimethylboroxine, 2,4,6-triethylboroxine, 2,4,6-trivinylboroxine, 2,4,6-trimethoxyboroxine, 2,4,6-trimethoxyboroxine, and triphenylboroxine; and halogen-substituted hydrocarbon groups such as tris(2,2,2-trifluoroethyl)borate, 2,4,6-tris(4-fluorophenyl)boroxine, and 2,4,6-tris(3,4,5-trifluorophenyl)boroxine.

[0147] The anion receptor having an aluminum atom includes an aluminum compound that functions as a Lewis acid, and has the formula AlX １ ３ (X １ is a halogen atom, which may be a fluorine atom), the formula: Al(OR ３５ ) ３ (R ３５ is a hydrocarbon group, which may be an alkyl group.

[0148] The anion receptor may also be an azaether. An azaether is an ether compound in which —O— is replaced by —NR Ｅ - (where R Ｅ is a hydrogen atom or an organic group). The azaether may be either a linear azaether or a cyclic azaether. The azaether may have an electron-withdrawing group, for example, in the hydrocarbon moiety.

[0149] The content of the anion receptor in the electrolyte composition may be, for example, 10 to 200 parts by mole, 30 to 180 parts by mole, 50 to 150 parts by mole, or 80 to 130 parts by mole relative to 100 moles of the structural unit (A) contained in the polymer capable of preferentially conducting alkali metal ions.

[0150] Some anion receptors function as coating-forming additives. When the electrolyte composition of the present embodiment contains an anion receptor, the electrolyte composition contains one or more anion receptors, one or more organic solvents, and one or more comparative coating-forming additives (three or more in total).

[0151] <Alkali Metal Salt> The electrolyte composition of the present embodiment may contain an alkali metal salt. When the electrolyte composition contains an alkali metal, the coating formed from the coating-forming additive contains alkali metal ions during formation, which is thought to further improve ionic conductivity.

[0152] The alkali metal salts include MF, MCl, MBr, MI, and MNO, where M is an alkali metal. ３ , MClO ４ , MPF ６ , MBF ４ , M ２ SO ４ , M[(C ｈ F ２ｈ＋１ ) SO ３ ] (h is 0 to 3), M[(C ｈ F ２ｈ＋１ ) SO ２ ] ２ N (h is 0 to 3), M{[(C ｈ F ２ｈ＋１ ) SO ２ ]N[(C ｉ F２ｉ＋１ ) SO ２ ]} (h and i are 0 to 3 (except when both h and i are 0)), MBOB (BOB is bisoxalatoborate). One or more alkali metal salts may be used. M is not particularly limited as long as it is an alkali metal, and may contain lithium, sodium, or potassium, or may contain lithium, sodium, or potassium. The alkali metal element contained in the alkali metal salt may be the same alkali metal element as the alkali metal element contained in the structural unit (A). The alkali metal salt may be an alkali metal salt other than MBOB, and may contain a sulfonyl group (-SO ２ The alkali metal salt may include an alkali metal salt containing an anion having the formula (I-), and may be at least one of alkali metal bis(fluorosulfonyl)imide (also referred to as MFSI) and alkali metal bis(trifluoromethanesulfonyl)imide (also referred to as MTFSI), or may be MTFSI.

[0153] The content of the alkali metal salt in the electrolyte composition may be, for example, 0.05 to 50 molar parts, 0.1 to 30 molar parts, 0.5 to 25 molar parts, or 1 to 20 molar parts, calculated as the alkali metal ion content of the alkali metal salt, relative to 100 moles of the total amount of the structural units (A) and (B) possessed by the polymer capable of preferentially conducting alkali metal ions. The content of the alkali metal salt in the electrolyte composition may be, for example, 0.05 to 40 mass%, 0.1 to 30 mass%, 0.5 to 25 mass%, or 1 to 20 mass%, relative to the total amount of the electrolyte composition.

[0154] <Negative Electrode> The negative electrode is not particularly limited and may contain a negative electrode active material and, if necessary, a conductive additive, a binder, etc. Examples of the negative electrode active material include simple elements such as Li, Si, P, Sn, Si—Mn, Si—Co, Si—Ni, In, and Au, alloys or composites containing these elements, carbon materials such as graphite, substances in which lithium ions are inserted between layers of the carbon material, and oxides containing titanium.

[0155] A laminate comprising a positive electrode, an electrolyte, and a negative electrode can be produced by stacking a positive electrode material, an electrolyte composition, and a negative electrode material. The positive electrode material can be prepared by mixing a positive electrode active material, a polymer, and other optional components. The negative electrode material can be prepared by mixing a negative electrode active material and other optional components.

[0156] [Production of Copolymer 1 (Polymer 1)] A copolymer of styrene and a monomer A1 represented by the following formula was produced as follows.

[0157] 3.121 g of monomer A1, 0.833 g of styrene, and 57.5 mg of azobisisobutyronitrile (AIBN) were dissolved in 70 mL of dehydrated acetonitrile, and the mixture was reacted at 60°C for 24 hours under a nitrogen atmosphere while adding tetralin as an internal standard substance to check the monomer consumption rate. The polymerization solution was dialyzed in acetonitrile and vacuum dried at 120°C to obtain 3.50 g (yield 89%) of copolymer 1. The monomer introduction ratio was A1:styrene = 54:46. １ The styrene was calculated from H-NMR. ２ and dried overnight. ２ The purity was improved by adding HCl and distilling under reduced pressure, and then the product was used.

[0158] Copolymer 1 has a number average molecular weight Mn = 9.3 × 10 ４ , weight average molecular weight Mw=3.0×10 ５ The molecular weight distribution Mw / Mn was 3.19.

[0159]

[0160] Monomer X was synthesized by adding an aqueous lithium acetate solution (14.0 mmol, 0.92 g) of the following compound to acetic anhydride (12.3 mL, manufactured by Tokyo Chemical Industry Co., Ltd.) and stirring the mixture at 70° C. for 3 hours.

[0161] [Positive electrode material 1] LiFePO as a positive electrode active material ４(LFP), the copolymer 1 produced as described above, carbon nanotubes (average diameter 10 nm, multi-layer), and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) were mixed in a mass ratio of 93.5:3:0.5:3 to obtain a positive electrode material 1. The details of the positive electrode active material are as follows: Nominal: LiFePO ４ Crystal structure: Pnma Average particle size: 1.0 μm

[0162] [Positive electrode material 2] The above LiFePO ４ (LFP), the copolymer 1 produced as described above, acetylene black (manufactured by Denka Co., Ltd., product name: HS-100, average particle size 35 to 45 nm), and PVDF-HFP were mixed in a mass ratio of 87:3:7:3 to obtain a positive electrode material 2.

[0163] (Porosity measurement of cathode material by mercury porosimetry) The porosities of cathode material 1 and cathode material 2 produced as described above were measured by mercury porosimetry. As a result, the porosity of cathode material 1 at 0.1 to 100 μm was 25%. On the other hand, the porosity of cathode material 2 at 0.1 to 100 μm was 22%. The measurement was carried out by gradually increasing the pressure from 0.00689 MPa up to 413.7 MPa. The cumulative pore volume obtained when pressurized up to 413.7 MPa was taken as the total volume of pores with pore sizes (diameters) of 0.1 to 100 μm.

[0164] (Observation by Scanning Electron Microscope (SEM)) The positive electrode materials were observed using a JCM-7000 manufactured by JEOL Ltd. Fig. 1 is an SEM image of positive electrode material 1. Fig. 2 is an SEM image of positive electrode material 2.

[0165] [Production of Electrolyte Composition 1 (Electrolyte 1)] Electrolyte composition 1 containing copolymer 1 produced as described above, poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and a 5 mass % fluoroethylene carbonate solution (ethylene carbonate:propylene carbonate = 1:1 (volume ratio) (Kishida Chemical Co., Ltd.) was used as the solvent) in a mass ratio of 25:12.5:2.8:37.5 was produced.

[0166] [Preparation of Electrolyte Composition 2 (Electrolyte 2)] Electrolyte composition 2 containing copolymer 1 prepared as described above, PVDF-HFP, LiTFSI, and the 5% by mass fluoroethylene carbonate solution described above in a mass ratio of 25:12.5:2.8:75 was prepared.

[0167] [Production of Electrolyte Composition 3 (Electrolyte 3)] Electrolyte composition 3 was produced containing copolymer 1 produced as described above, PVDF-HFP, LiTFSI, and the above 5 mass% fluoroethylene carbonate solution in a mass ratio of 20:10:16.9:60.

[0168] [Production of Electrolyte Composition 4 (Electrolyte 4)] Electrolyte composition 4 was produced containing copolymer 1 produced as described above, PVDF-HFP, and an organic solvent (ethylene carbonate:propylene carbonate = 1:1 (volume ratio) (Kishida Chemical Co., Ltd.) diluted in a mass ratio of 20:10:60. Electrolyte composition 4 did not contain LiTFSI, which is a film-forming additive.

[0169] (Charge / Discharge Test) In a glove box under a dry argon atmosphere, evaluation cells of the coin-type battery CR2032 of the Examples and Comparative Examples shown in the table below were assembled. Specifically, each layer was laminated in the evaluation cell in the following order to prepare a test laminate: (Lithium / Electrolyte Composition / Positive Electrode Material)

[0170] Using the above evaluation cell, 2.5-4.0 V (vs. Li / Li ＋ The cycle retention rate after 10 cycles was measured by carrying out five charge-discharge measurements within the range of 10 cycles. The results are shown in Table 1.

[0171]

Claims

1. A battery comprising a positive electrode, a negative electrode, and an electrolyte disposed between the positive electrode and the negative electrode, wherein the positive electrode contains a positive electrode active material and a polymer capable of preferentially conducting alkali metal ions, and has a porosity of 23% or more at 0.1 to 100 μm as measured by mercury intrusion porosimetry, the electrolyte is a membrane containing a polymer capable of preferentially conducting alkali metal ions, and the polymer capable of preferentially conducting alkali metal ions in the electrolyte is swollen with a solution containing a film-forming additive and an organic solvent.

2. The battery of claim 1, wherein the film-forming additive is fluoroethylene carbonate or vinylene carbonate.

3. The battery according to claim 1 or 2, wherein the organic solvent is one or more solvents selected from the group consisting of carbonate-based solvents, ether-based solvents, fluorine-based solvents, nitrile-based solvents, lactone-based solvents, phosphate-based solvents, and sulfone-based solvents.

4. The battery according to claim 1 or 2, wherein the polymer capable of preferentially conducting the alkali metal ions contained in the positive electrode and the electrolyte has an alkali metal ion and an anionic functional group having the alkali metal ion as a counter cation.

5. The battery of claim 4, wherein the alkali metal ions comprise lithium ions or sodium ions.

6. The battery according to claim 4, wherein the anionic functional group has one or more groups selected from the group consisting of an alkali metal substituted sulfonylimide group, an alkali metal substituted sulfonic acid group, an alkali metal substituted carboxylic acid group, and an alkali metal substituted phenolic hydroxyl group.

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