Battery

Abstract

The present disclosure provides a battery comprising: a positive electrode having a porous structure; a negative electrode; and a quasi-solid electrolyte disposed between the positive electrode and the negative electrode, wherein the positive electrode contains a first polymer and a conductive auxiliary agent, the proportion of holes having a pore diameter of 0.1-100 μm to all holes, as measured by a mercury intrusion method, is at least 23%, and the quasi-solid electrolyte contains a second polymer having a polar functional group, an ionic compound, and particles.

Description

battery

[0001] The present disclosure relates to batteries.

[0002] Batteries that use metal ions as charge carriers for charging and discharging (e.g., lithium ion batteries) have been the subject of vigorous research due to their high capacity. Known electrolytes used in such batteries include solutions of alkali metal salts containing organic solvents or ionic liquids. Meanwhile, research into solid electrolytes and polymer electrolytes has been ongoing as alternatives to liquid electrolytes, with a view to improving safety and processability (see Patent Documents 1 and 2).

[0003] Although lithium-ion batteries are superior in terms of battery performance, reserves of the raw material lithium are said to be smaller than those of other alkali metals, and research is also underway to improve the performance of batteries that use alkali metal ions other than lithium (e.g., sodium, potassium, etc.) as charge carriers.

[0004] Korean Patent Publication No. 10-2016-0050870 Special Publication No. 2023-511906

[0005] Secondary batteries such as lithium-ion batteries, particularly those used in mobile and automotive applications, require high-speed charge / discharge. However, according to the studies of the present inventors, it has been confirmed that the observed capacity of batteries using polymer electrolytes is significantly reduced when the charge / discharge rate is increased. Therefore, there is room for improvement in the cycle characteristics of batteries using polymer electrolytes when the charge / discharge rate is increased.

[0006] An object of the present disclosure is to provide a battery that has a charge / discharge rate of 6 C or more and excellent cycle stability.

[0007] The present disclosure provides, for example, the following [1] to [5].

[0008] [1] A battery having a positive electrode having a porous structure, a negative electrode, and a quasi-solid electrolyte disposed between the positive electrode and the negative electrode, wherein the positive electrode contains a first polymer and a conductive additive, and a ratio of pores having a pore diameter of 0.1 to 100 μm to all pores measured by mercury intrusion porosimetry is 23% or more, and the quasi-solid electrolyte contains a second polymer, an ionic compound, and particles. [2] The battery according to [1], wherein the ionic compound contains a lithium salt compound, and the content of the lithium salt compound is 0.1 to 3 equivalents per equivalent of the substance amount of lithium ions in the second polymer. [3] The battery according to [1] or [2], wherein the first polymer and the second polymer are polymers capable of preferentially conducting alkali metal ions. [4] The battery according to any one of [1] to [3], wherein the positive electrode further comprises a positive electrode active material, the first polymer is a polymer capable of preferentially conducting alkali metal ions, and the content of the first polymer is 0.5 to 10 mass % relative to the total mass of the positive electrode, where the total mass of the positive electrode is 100 mass %. [5] The battery according to any one of [1] to [4], wherein the conductive additive comprises fibrous carbon.

[0009] According to the present disclosure, a battery having a charge / discharge rate of 6 C or more and excellent cycle stability can be provided.

[0010] Fig. 1 is a diagram showing the results of a charge / discharge test on the battery of Example 1. Fig. 2 is a diagram showing the results of a charge / discharge test on the battery of Example 2. Fig. 3 is a diagram showing the results of a charge / discharge test on the battery of Comparative Example 1. Fig. 4 is a diagram showing the results of a charge / discharge test on the battery of Comparative Example 2.

[0011] Hereinafter, embodiments of the present disclosure will be described, occasionally with reference to the drawings. However, the following embodiments are merely examples for explaining the present disclosure, and are not intended to limit the present disclosure to the following content. In this specification, a numerical range indicated with the symbol "to" includes a lower limit and an upper limit. In other words, a numerical range indicated as "x to y" means a range equal to or greater than x and equal to or less than y.

[0012] Unless otherwise specified, the materials exemplified in this specification can be used singly or in combination of two or more. When a plurality of substances corresponding to each component are present in the composition, the content of each component in the composition means the total amount of the plurality of substances present in the composition, unless otherwise specified.

[0013] In this specification, the term "substituent" may refer to either an organic group or a group other than an organic group (an inorganic group), unless otherwise specified. In this specification, 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, unless otherwise specified. In this specification, the "group other than an organic group (an inorganic group)" may be either an electron-withdrawing group or an electron-donating group. Specific examples of the "group other than an organic group (an inorganic group)" include a halogen atom, -NH ２ , -NH ３ ＋ , —CN, sulfonic acid group and its salts or esters, —NO ２ etc.

[0014] Unless otherwise specified, the term "organic group" used herein refers to, regardless of the valence of the organic group, hydrocarbon groups, groups in which some carbon atoms of a hydrocarbon group are replaced with heteroatoms, and groups in which at least one hydrogen atom of the group is substituted with a substituent. When the "organic group" has a ring structure, the ring may be either a heterocycle or a carbocycle, and may be either a monocycle or a fused ring. Unless otherwise specified, examples of heteroatoms substituting the carbon atoms include boron atoms, oxygen atoms, nitrogen atoms, silicon atoms, phosphorus atoms, and sulfur atoms. In other words, the "organic group" may include, within its structure, 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.

[0015] Unless otherwise specified, the term "hydrocarbon group" as used herein may be either a saturated hydrocarbon group or an unsaturated hydrocarbon group, and may be either an aliphatic hydrocarbon group or an aromatic hydrocarbon group. In this specification, the term "aliphatic hydrocarbon group" may be either a straight-chain hydrocarbon group, a branched-chain hydrocarbon group, or a cyclic hydrocarbon group. In this specification, the term "aromatic hydrocarbon group" refers to a hydrocarbon group having an aromatic moiety such as a benzene ring, and may optionally have an aliphatic moiety, unless otherwise specified. In this specification, the term "cyclic hydrocarbon group" refers to a hydrocarbon group having an aliphatic carbon ring moiety, and may optionally have a straight-chain or branched-chain aliphatic moiety.

[0016] Specific examples of the "organic group" used herein include substituted or unsubstituted hydrocarbon groups, groups 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 groups in which a hydrogen atom of the group is substituted with a substituent such as a halogen atom, and groups having a heterocycle.

[0017] One embodiment of a battery according to the present disclosure includes a positive electrode having a porous structure, a negative electrode, and a quasi-solid electrolyte disposed between the positive electrode and the negative electrode. In the battery, the positive electrode and the quasi-solid electrolyte, and the negative electrode and the quasi-solid electrolyte may be disposed so as to be in contact with each other, and the positive electrode, the quasi-solid electrolyte, and the negative electrode may be stacked in this order.

[0018] <Positive electrode> The positive electrode has a porous structure, and the ratio of pores having a pore diameter of 0.1 to 100 μm to all pores (porosity) measured by mercury porosimetry is 23% or more. By adjusting the porosity of the positive electrode to this range, even if aggregation of electrolyte components occurs during charging and discharging of the battery, a significant decrease in metal ion conductivity can be suppressed.

[0019] The porosity of the positive electrode may be, for example, 23 to 50%, 23 to 40%, 24 to 35%, or 24 to 30%. Examples of methods for adjusting the porosity include a method in which fibrous carbon is added as a conductive additive to suppress aggregation of the first polymer and the conductive additive, or a method in which the first polymer and the positive electrode active material are first mixed and then the conductive additive is added. The method of adding the conductive additive later is more effective when a powder such as acetylene black is used as the conductive additive.

[0020] The positive electrode includes a first polymer and a conductive additive.

[0021] (First Polymer) The first polymer may be a polymer capable of conducting alkali metal ions, or may be a polymer capable of preferentially conducting alkali metal ions. The first polymer may be one whose transference number of the alkali metal ions under the following conditions (X) and (Y) is, for example, 0.4 or more, 0.5 or more, 0.6 or more, or 0.7 or more.

[0022] In this specification, a polymer "having the ability to preferentially conduct alkali metal ions" means that it satisfies at least one of the following conditions (X) and (Y): Condition (X): 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. Condition (Y): 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.

[0023] Under the above conditions (X) and (Y), the alkali metal ion contained in the composition whose transference number is to be measured may be a counter cation of the anionic functional group of the polymer. Examples of nonionic plasticizers include at least one of an organic solvent and another resin such as a fluororesin. The organic solvent may be a mixed solvent of ethylene carbonate and propylene carbonate (volume ratio 1:1). The fluororesin is preferably a resin having a carbon chain as its main chain. The carbon chain may be formed by radical polymerization of an ethylenically unsaturated group. The fluororesin may be PVDF-HFP. The organic solvent may be an aprotic solvent. The aprotic solvent may be at least one selected from the group consisting of carbonate solvents, fluorine solvents, and ether solvents.

[0024] The first polymer may have an anionic functional group having an alkali metal ion as a counter ion, and may include an alkali metalated group as a side group. Here, the alkali metalated group in this specification refers to a group in which the anionic functional group, which is the conjugate base of the acid form of the group, forms a salt with an alkali metal ion. Examples of such groups include an alkali metalated phenolic hydroxyl group, an alkali metalated carboxylic acid group, an alkali metalated sulfonic acid group, and an alkali metalated sulfonylimide group.

[0025] The alkali metal substituted phenolic hydroxyl group is an —OA group (—O) in which H of the —OH group, which is a phenolic hydroxyl group, is substituted with an alkali metal element A. － A ＋ An 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, for example. － 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 sulfonylimide group refers to 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 ＋ group), and examples thereof include a lithiated sulfonylimide group.

[0026] The structure of the first polymer is not particularly limited, but examples thereof include those having a carbon chain as the main chain. The carbon chain may be formed by radical addition polymerization of a monomer having an ethylenically unsaturated group.

[0027] The alkali metal element A may contain at least one selected from the group consisting of lithium, sodium, potassium, rubidium, and cesium, may contain at least one selected from the group consisting of lithium, sodium, and potassium, may contain at least one of lithium and sodium, or may contain lithium.

[0028] The content of one alkali metal element among the alkali metal elements contained in the first polymer may be 80 mol% or more, 85 mol% or more, or 90 mol% or more. The one alkali metal element may be lithium, sodium, or potassium, or may be lithium, sodium, or lithium.

[0029] The first polymer may have a structural unit (A). The structural unit (A) is a structural unit having a functional group (A), and may include 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), R １ ~R ３ and Y are omitted, and in formula (A2), R ４ , R ５ The structure excluding Z is also simply called an ethylene unit.

[0030] (In formula (A1), Y is a monovalent group modified with an alkali metal and contains a functional group (A). 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 an alkali metal group. １ ~R ３ At least one of may be a functional group other than a hydrogen atom or a fluorine atom.

[0031] (In formula (A2), Z is a divalent group modified with an alkali metal and contains a functional group (A). 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 an alkali metalated group.

[0032] In formula (A1), Y contains at least the functional group (A), which may contain at least one of an alkali metal carboxylic acid group and an alkali metal phenolic hydroxyl group. The first polymer may contain one or more structural units (A) having different functional groups as Y.

[0033] In formula (A1), R 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. In formula (A1), R １ ~R ３ At least one of may be a hydrogen atom, or all of may be hydrogen atoms.

[0034] In formula (A1), R １ and R ２One 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 (A1), 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.

[0035] When Y in formula (A1) 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 having a -COOA 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. The number of carbon atoms in the organic group includes the number of carbon atoms constituting the -COOA group. The monovalent organic group having a -COOA group may have one or more -COOA groups, or may have one -COOA group. When Y is a monovalent organic group having a -COOA group, Y may have an electron-withdrawing group such as a halogen atom in addition to the -COOA group.

[0036] In formula (A1), Y is -R ９ -COOA, where R ９ is a divalent organic group or a covalent bond (i.e., Y is the -COOA group itself). 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, 1, or 2. ９ When contains a carbon atom, R ９ is R ９ may be a divalent group other than a group in which all carbon atoms included in R are substituted with fluorine atoms. ９When contains a carbon atom, R ９ At least one of the carbon atoms contained in is bonded to a hydrogen atom or a substituent other than a fluorine atom.

[0037] When Y in formula (A1) has an alkali metal-substituted phenolic hydroxyl group, Y can be, for example, R １０ -Y ２ where R １０ is a divalent substituent (linking group) or a covalent bond, and may be a covalent bond. ２ 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. The aromatic ring may be condensed with another ring structure. For example, Y ２ may have a group represented by any one of the following formulae (A21) to (A26).

[0038] (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 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 Ｅ９At 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.

[0039] The groups represented by formulae (A21) to (A26) have at least one -OA group, and the number of -OA groups may be, for example, 1 to 3, 1, or 2, or may be 1 -OA group.

[0040] In formulae (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.

[0041] 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.

[0042] In formula (A1), Y is R １０ -Y ２ is a group represented by the formula １０ When R is a divalent substituent, the substituent may be a divalent organic group. The number of carbon atoms in the divalent organic group may be, for example, 1 to 15, 1 to 10, 1 to 8, or 1 to 5. １０ may have a heterocyclic ring or a ring having an imide group.

[0043] When Y in formula (A1) is a sulfonic acid group modified with an alkali metal, examples of Y include a group represented by the following formula (A3). (In formula (A3), R １９is a covalent bond or a divalent organic group. A is an alkali metal element.

[0044] In formula (A3), 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. １９ is a divalent organic group, and when the divalent organic group is a hydrocarbon group, at least one of the carbon atoms constituting the hydrocarbon group is bonded to a hydrogen atom. That is, the divalent organic group in formula (A3) is a group other than a perfluorinated hydrocarbon group.

[0045] The alkali metal sulfonic acid group represented by formula (A3) is, for example, —SO ３ A, -CH ２ -SO ３ A and -C ６ H ４ -SO ３ Examples include A.

[0046] When Y in formula (A1) is a sulfonylimide group modified with an alkali metal, examples of Y include a group represented by the following formula (A4). (In formula (A4), R ２０ is a covalent bond or a divalent organic group, and R ２１ is a hydrogen atom or a monovalent substituent. ＋ is an alkali metal ion.)

[0047] R in formula (A4) ２０ When is a divalent organic group, 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.

[0048] When the structural unit (A) of the first polymer has a structural unit represented by formula (A2), in formula (A2), Z bonds to two carbon atoms of the ethylene unit to form a ring. The ring may be either a carbocyclic ring or a heterocyclic ring. Furthermore, the ring may be either aliphatic or aromatic. Examples of heterocyclic rings include rings having an imide group, such as a maleimide ring. A functional group (A) may be bonded to the ring. The number of carbon atoms possessed by Z may be, for example, 1 to 20, 1 to 15, 2 to 10, or 3 to 8.

[0049] The structural unit (A2) may be a group containing a maleimide ring having an alkali metal-substituted group, and examples thereof include the following structural unit (A5). (In formula (A5), 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 (A5) is bonded to another structural unit.

[0050] The number of carbon atoms owned by X in formula (A5) may be, for example, 1 to 15, 2 to 10, or 3 to 8. When X is a hydrocarbon group, the hydrocarbon group may be, for example, 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 phenylene group or a substituted phenylene group substituted with an alkyl group, a halogen atom, an electron-withdrawing group, or the like.

[0051] Y in formula (A5) １ is a monovalent organic group, Y １ The number of carbon atoms contained in Y in formula (A5) may be, for example, 1 to 15, 1 to 10, 1 to 8, 1 to 5, or 1 to 3. １When Y is a hydrocarbon group, the hydrocarbon group 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.

[0052] In the case where the structural unit (A) of the first polymer has a structural unit represented by formula (A2), and where formula (A2) contains a sulfonic acid group modified with an alkali metal, examples of Z in formula (A2) include a group represented by formula (A6) below. (In formula (A6), R １８ is a covalent bond or a divalent organic group. A is an alkali metal element.

[0053] In formula (A6), 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. １８ When contains a carbon atom, R １８ is R １８ may be a divalent group other than a group in which all carbon atoms included in R are substituted with fluorine atoms. １８ When contains a carbon atom, R １８ At least one of the carbon atoms contained in is bonded to a hydrogen atom or a substituent other than a fluorine atom.

[0054] The alkali metal sulfonic acid group represented by formula (A6) is, for example, —SO ３ A, -CH ２ -SO ３ A and -C ６ H ４ -SO ３ Examples include A.

[0055] The first polymer may have an alkali metal-modified group other than the functional group (A) (hereinafter also referred to as functional group (A')). Examples of such groups include an alkali metal-modified alcohol group and an alkali metal-modified phosphate group. The functional group (A') may be contained in the structural unit (A), or may be contained in a structural unit other than the structural unit (A) (i.e., a structural unit that does not have the functional group (A) but has the functional group (A'), and does not fall under any of the structural units (B) described below; hereinafter also referred to as structural unit (A')). The first polymer may also contain a structural unit having a functional group that functions as an anion receptor (hereinafter also referred to as structural unit (B)).

[0056] In addition to the first polymer, the positive electrode may contain another polymer that does not contain the functional group (A) but has the ability to preferentially conduct alkali metal ions. Examples of the other polymer include a polymer containing at least one of the structural unit (A') and the structural unit (B) (hereinafter referred to as polymer (B)). The polymer (B) does not contain the functional group (A).

[0057] 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.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] The structural unit (B) may contain at least one structural unit represented by the following formula (B): １１ ~R １３ The structure excluding W is also simply called an ethylene unit. (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 １３may be hydrogen atoms, or all of may be hydrogen atoms.)

[0062] 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.

[0063] In formula (B), R １１ ~R １３ is a monovalent substituent, 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.

[0064] 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 １３ form 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.

[0065] W in formula (B) preferably has a group represented by the following formula (B1). (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 R１７ may be the same group or different groups.)

[0066] W in formula (B1) Ｂ may be at least one of an aluminum atom and a boron atom, and may be a boron atom.

[0067] R in formula (B1) 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 When is a divalent organic group, the organic group may be, for example, 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.

[0068] R in formula (B1) １６ or R １７ is a halogen atom, R １６ or R １７ R may be any of a fluorine atom, a chlorine atom, a bromine atom and an iodine atom, and may also be a fluorine atom. １６ or R １７ may be the same or different.

[0069] R in formula (B1) 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. １６ or R １７ is, for example, 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. ＢThe 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.

[0070] The group represented by formula (B1) may be a group represented by formula (B1a) below or a group represented by formula (B1b) below. (In formula (B1a), 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 X １１ and X １２ are each independently an oxygen atom or a covalent bond. １１ is a covalent bond, R ２２ is a hydrogen atom, a halogen atom, or a monovalent organic group. １１ is an oxygen atom, R ２２ is a hydrogen atom or a monovalent organic group. １２ is a covalent bond, R ２３ is a hydrogen atom, a halogen atom, or a monovalent organic group. １２ is an oxygen atom, R ２３ 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), 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 X １３ and X １４ are each an oxygen atom or a covalent bond, and R ２４ is a divalent organic group.

[0071] In formula (B1a), R ２２ or R ２３When 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. ２２ or R ２３ When is a halogen atom, the halogen atom may be a fluorine atom.

[0072] R in formula (B1a) ２２ and R ２３ 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 , and -C ６ H ｎ (CF ３ ) ５－ｎ (n is an integer from 0 to 4, and may be 1 or 2).

[0073] In formula (B1b), R ２４is a divalent organic group, and the number of carbon atoms in the divalent organic group may be, for example, 1 to 20, 1 to 15, 2 to 10, or 3 to 8. 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.

[0074] R in formula (B1b) ２４ For example, -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., in which the hydrogen atoms are partially or entirely substituted with fluorine atoms. ２４ More specifically, —C(CH ３ ) ２ -C(CH ３ ) ２ - may be.

[0075] The first polymer may have a structural unit (C) that is not any of the structural units (A), (A'), and (B). The structural unit (C) may include a structural unit 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 ２８and form a ring. * indicates the bonding site of the structural unit (C) to other structural units.

[0076] In formula (C), R ２５ may be a monovalent organic group. ２５ The number of carbon atoms contained in may be, for example, 1 to 40, 1 to 20, 2 to 15, or 4 to 13. １ -R ２９ In this case, Z may be a group represented by 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 Z may be a group represented by C(=O)-. 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.

[0077] The divalent linking group Z １ is -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 Together with Z it forms a ring. １ But, -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 It forms a ring together with R. ２９ , R ３８ and R ３９ The number of carbon atoms in the monovalent organic group as R may be 1 to 20, or 1 to 10. ３８ When is a monovalent organic group, it may be a monovalent hydrocarbon group having 1 to 20 carbon atoms.

[0078] The divalent linking group Z １is 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 ２９ When R is a hydrocarbon group, the hydrocarbon group may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group. ２９ may be a monovalent organic group other than a hydrocarbon group or a hydrocarbon group having a ring structure.

[0079] The divalent linking group Z １ When is —O—, W ０ as alkyl ethers, ０ The monovalent organic group may be a monovalent organic group other than the group represented by —H. ２６ ~R ２８ When R is a monovalent organic group, the monovalent organic group is ２５ The same examples as those given above are included.

[0080] In a group having an aromatic ring (for example, the above-mentioned aromatic hydrocarbon group), 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 ６１ - (W １ -R ６２ ) ｎ -W ２ R ６３ Examples include groups represented by the formula: -R ６１ - (W １ -R ６２ ) ｎ -W ２ R ６３ 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—.

[0081] R in the monovalent organic group ６１is 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. 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.

[0082] R in the monovalent organic group ６２ 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 group may be a substituted hydrocarbon group). Examples of such substituents include halogen atoms such as fluorine atoms. The divalent hydrocarbon group may be 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, or may be an ethylene group.

[0083] The above formula: -R ６１ - (W １ -R ６２ ) ｎ -W ２ R ６３ In the group represented by the formula (I), n may be, for example, 1 to 10, 1 to 5, or 1 to 3. The n may be an integer or a rational number (for example, n may be an average value across the structural units (B) contained in the polymer). ６２ When there are multiple, they may be different or the same.

[0084] R in the monovalent organic group ６３may be a hydrogen atom or a monovalent 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 atoms 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 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, or may be a methyl group.

[0085] When the first polymer has the structural unit (C), the structural unit (C) may include a structural unit derived from a monomer represented by the following formula (C1). (In formula (C1), m is 0 to 4, and n is 0 to 10. R ３１ 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.

[0086] 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).

[0087] When the first polymer has the structural unit (C), R ２６ and R ２７ One of them is R ２８ When R forms a ring together with the structural unit (C), the ring may have, for example, 4 to 10 members, 4 to 8 members, or 5 to 7 members. ２７ is R ２８ When the structural unit (C) is taken together with the structural unit (C) to form a ring, the structural unit (C) may be the following structural unit (C2). (In formula (C2), X represents an oxygen atom or —NR３１ - is a tertiary amino group represented by R ３１ is a monovalent organic group, and R ２５ and R ２６ are each independently a hydrogen atom or a monovalent substituent.

[0088] In formula (C2), X is -NR ３１ When the tertiary amino group is represented by -, R ３１ The number of carbon atoms contained in the R may be, for example, 1 to 20, 1 to 15, or 2 to 10. ３１ 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.

[0089] The ratio of the structural unit (A) to all structural units contained in the first polymer may be 0.2 to 0.95, 0.2 to 0.8, 0.3 to 0.7, or 0.4 to 0.6.

[0090] The ratio of the structural unit (C) to all structural units contained in the first 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 first polymer may be 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, or 0.3 or less.

[0091] The total proportion of the structural units (A) and (C) relative to all structural units contained in the first 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.

[0092] The content of the structural unit (A) relative to the total mass of the first polymer may be, for example, 25 to 95 mass %, 40 to 90 mass %, or 50 to 90 mass %.

[0093] The content of the structural unit (C) relative to the total mass of the first 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 first polymer may be, for example, 75 mass% or less, 60 mass% or less, 50 mass% or less, or 25 mass% or less.

[0094] The sum of the contents of the structural units (A) and (C) relative to the total mass of the first polymer may be, for example, 90% by mass or more, 95% by mass or more, or 98% by mass or more.

[0095] When the first polymer contains the structural unit (B), the molar ratio m of the structural unit (B) to all structural units contained in the first 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 first polymer may be, for example, more 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.

[0096] The number average molecular weight (Mn) of the first 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 first 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 first polymer may be, for example, 1.0 to 5.0, 1.2 to 3.0, or 1.3 to 2.5.

[0097] The number average molecular weight and weight average molecular weight of the first polymer in this specification can be measured by gel permeation chromatography (GPC) performed under the following conditions. A standard sample of polymethyl methacrylate (manufactured by Polymer Laboratories, Mn of 800 to 2,200,000) is used as the standard substance for creating a calibration curve. <GPC Measurement Conditions> Apparatus: High-performance liquid chromatograph PU-2080 precision pump RI-2031 refractive-index detector UV-2075 UV / vis detector, manufactured by JASCO Corporation Column: Shodex KF-805L (exclusion limit: 4 × 10 ６ , particle size: 10 μm, pore size: 5000 Å, inner diameter: 0.8 cm, length: 30 cm) Temperature: 40° C. Solvent: dimethylformamide (DMF) Flow rate: 1.0 mL / min Back pressure: 3.0 MPa Detection: RI Sample concentration: 0.5 mass % DMF solution Injection volume: 10 μL

[0098] The first polymer can be produced by polymerizing the corresponding monomers, for example, by a polymerization reaction such as radical addition polymerization.

[0099] (Conductive Aid) The conductive aid may be a carbon material. Examples of the carbon material include graphene, graphite, carbon black, fullerene, carbon nanotubes, and carbon fibers. Examples of graphite include natural graphite (such as flake graphite) and artificial graphite. Examples of carbon black include acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black. Examples of carbon fibers include vapor-grown carbon fibers (VGCF).

[0100] From the viewpoint of increasing the porosity of the positive electrode, the carbon material preferably includes fibrous carbon such as carbon nanotubes and carbon fibers, and may be fibrous carbon such as carbon nanotubes and carbon fibers.

[0101] The carbon nanotubes may be either single-walled or multi-walled, and may be multi-walled. The carbon nanotubes may have metallic conductivity. The carbon nanotubes may have a tensile strength of 50 to 70 MPa. The BET specific surface area of ​​the carbon nanotubes may be, for example, 400 m ２ The carbon nanotubes may have a ratio of the G band intensity to the D band intensity (G / D ratio) of, for example, 10 or less in a Raman spectrum analysis obtained by Raman spectroscopy.

[0102] The carbon nanotubes may have an average length of, for example, 1 μm or more, or 5 μm or more, and may have an average diameter of, for example, 0.4 to 100 nm, 0.5 to 50 nm, or 1 to 30 nm.

[0103] The content of the conductive additive 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%, based on the total mass of the positive electrode.

[0104] (Other Components) The positive electrode may contain other components in addition to the first polymer and the conductive additive, such as a positive electrode active material and a binder resin.

[0105] [Positive Electrode Active Material] The positive electrode may further include a positive electrode active material. Examples of the positive electrode active material include a composite metal oxide containing an alkali metal and at least one metal element selected from the group consisting of a transition metal element and Al. Examples of the alkali metal include lithium, sodium, or potassium. The alkali metal is preferably lithium, and in this case, examples of the positive electrode active material include a lithium composite metal oxide. 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.

[0106] Specific examples of lithium composite metal oxides include LiCoO ２ , LiNiO２ , 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 FeSiO ４ , and Li ２ MnSiO ４ etc.

[0107] When the alkali metal is an element other than lithium, specific examples of the composite metal oxide include those in which Li in the above specific examples is replaced with another alkali metal.

[0108] 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 %, based on the total mass of the positive electrode.

[0109] The positive electrode may further include a positive electrode active material, and the first polymer may be a polymer capable of preferentially conducting alkali metal ions. In this case, the content of the first polymer may be, for example, 0.5 to 10 mass%, 0.5 to 8 mass%, 1 to 8 mass%, or 1 to 5 mass%, relative to the total mass of the positive electrode being 100 mass%.

[0110] [Binder Resin] Examples of binder resins include fluorine-based resins and synthetic rubbers. The fluorine-based resin is preferably a resin having a carbon chain as the main chain. The carbon chain may be formed by radical polymerization of a compound having an ethylenically unsaturated group. Examples of fluorine-based resins include poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) and polyvinylidene fluoride (PVDF). Examples of synthetic rubbers include SBR (styrene butadiene rubber).

[0111] 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 % based on the total mass of the positive electrode.

[0112] The negative electrode includes a negative electrode active material, such as a simple substance of an element such as Li, Si, P, Sn, Si—Mn, Si—Co, Si—Ni, In, or Au, an alloy or composite containing these elements, a carbon material such as graphite, a substance in which lithium ions are inserted between layers of the carbon material, or an oxide containing titanium.

[0113] The negative electrode may contain, for example, a conductive additive, a binder, and the like, as needed.

[0114] <Quasi-Solid-State Electrolyte> The quasi-solid-state electrolyte includes a second polymer, an ionic compound, and particles.

[0115] (Second Polymer) The second polymer may be a polymer capable of conducting alkali metal ions, or may be a polymer capable of preferentially conducting alkali metal ions. Examples of the second polymer include polyether, fluorine-based resin, polymers having polar functional groups, and polymers having anionic functional groups with alkali metal ions as counter ions.

[0116] Examples of polyethers include polyalkylene oxides, etc. Examples of polyalkylene oxides include polyethylene oxides, etc.

[0117] The fluororesin may include a resin having a carbon chain as the main chain. The carbon chain may be formed by radical polymerization of an ethylenically unsaturated group. Examples of the fluororesin include polytetrafluoroethylene (PTFE), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), and polyvinylidene fluoride (PVDF).

[0118] Examples of polymers having anionic functional groups with alkali metal ions as counter ions include the polymers exemplified as the first polymer. The description of the first polymer above can be applied to the second polymer. The second polymer may be the same as or different from the first polymer, and is preferably the same. When the second polymer is a polymer having polar functional groups or a polymer having anionic functional groups with alkali metal ions as counter ions, hydrogen bond formation between polymers or within polymer molecules or ionic bond formation via alkali metal ions can reduce or restrict the mobility of alkali metal ions that are originally intended to migrate between the functional groups of the polymer, potentially resulting in a failure to achieve the expected ionic conductivity. In contrast, the quasi-solid electrolyte according to the present disclosure contains particles, which can inhibit the formation of hydrogen bonds as described above by functional groups present on the particle surface, and sufficient ionic conduction can be expected even when the second polymer species is a polymer such as the one described above.

[0119] The content of the second polymer may be, for example, 1 to 80 mass %, 3 to 70 mass %, 5 to 60 mass %, or 10 to 40 mass % based on the total mass of the quasi-solid electrolyte.

[0120] (Ionic Compound) The ionic compound may be, for example, an alkali metal salt. Examples of the alkali metal salt 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 F２ｈ＋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 F ２ｉ＋１ ) SO ２ ]} (h and i are 0 to 3), and MBOB (BOB is bisoxalatoborate). The alkali metal salts may be used alone or in combination of two or more. The alkali metal M is not particularly limited as long as it is an element classified as an alkali metal, and may, for example, contain lithium, sodium, or potassium, or may contain lithium or sodium, or may contain lithium. 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) of the second polymer. The ionic compound may contain a lithium salt compound.

[0121] The content of the alkali metal salt in the quasi-solid electrolyte may be, for example, 0.1 to 200 mol %, 2.5 to 150 mol %, 5 to 100 mol %, or 10 to 60 mol % in terms of alkali metal ions contained in the alkali metal salt, relative to the total amount of the structural units (A) in the second polymer.

[0122] The content of the lithium salt compound may be, for example, 0.1 to 3 equivalents, 0.22.5 equivalents, 0.25 to 2 equivalents, or 0.5 to 1 equivalent per equivalent of the substance amount of lithium ions in the second polymer.

[0123] (Particles) The particles contained in the quasi-solid electrolyte may be, for example, inorganic particles or organic particles. The particles may be non-conductive particles. The material of the particles is preferably one having the following conductivity measured at 25° C., for example, 1.0×10 －６ Sm －１ Below, 1.0 x 10 －７ Sm －１ or less, or 1.0 x 10 －１０ Sm －１It may be the following:

[0124] Examples of inorganic particles include oxide particles, nitride particles, carbide particles, carbon particles, sulfur particles, and silicate mineral particles. Examples of oxide particles include silicon oxide particles (silica particles), aluminum oxide particles (alumina particles), and titanium oxide particles (titania particles). Examples of nitride particles include boron nitride particles and aluminum nitride particles. Examples of carbide particles include silicon carbide particles. Examples of silicate mineral particles include mica. Examples of organic particles include acrylic particles and melamine particles.

[0125] The average particle size of the particles may be, for example, 500 nm or less, 300 nm or less, 200 nm or less, 150 nm or less, 100 nm or less, or 80 nm or less, or 1 nm or more, 3 nm or more, or 5 nm or more. The average particle size of the particles may be 1 to 500 nm, 1 to 300 nm, 3 to 200 nm, 3 to 150 nm, 5 to 100 nm, 5 to 80 nm, or 5 to 50 nm or less. In this specification, the average particle size of the particles refers to the particle size (D50) at which the integrated value from the small particle size reaches 50% in the volume-based particle size distribution measured using a laser diffraction particle size distribution analyzer. Examples of the laser diffraction particle size distribution analyzer that can be used include "SALD2200" (trade name) and "SALD2300" (trade name) manufactured by Shimadzu Corporation. The particles may be so-called nanoparticles.

[0126] The maximum particle diameter of the primary particles of the particles may be, for example, 500 nm or less, 300 nm or less, 200 nm or less, 150 nm or less, 100 nm or less, or 80 nm or less, or 1 nm or more, 3 nm or more, or 5 nm or more. The maximum value of the primary particle diameter (maximum particle diameter) of the particles can be determined by analyzing images acquired with a scanning electron microscope or a transmission electron microscope. More specifically, from the images acquired with a scanning electron microscope or a transmission electron microscope, 100 particles that are visually determined to be large are selected from the primary particles of the particles to be measured, and the particle diameters of the selected particles are measured, and the maximum value is taken as the maximum particle diameter.

[0127] The particle content may be, for example, 50% by mass or less, 40% by mass or less, 35% by mass or less, or 30% by mass or less, or 0.1% by mass or more, 1% by mass or more, 5% by mass or more, 10% by mass or more, or 15% by mass or more, based on the total mass of the quasi-solid electrolyte. The particle content may be, for example, 0.1 to 50% by mass, 1 to 40% by mass, 5 to 35% by mass, 10 to 30% by mass, or 15 to 25% by mass, based on the total mass of the quasi-solid electrolyte.

[0128] (Other Components) The quasi-solid electrolyte may contain other components in addition to the second polymer, ionic compound, and particles. Examples of other components include a binder resin, multiple organic solvents, porous materials, coating-forming additives, fabrics such as nonwoven fabrics, viscosity modifiers, and anion receptors. The binder resin described above for the positive electrode can be used, and the binder resins for the positive electrode and the negative electrode may be the same or different. In the quasi-solid electrolyte, the second polymer may be swollen by an organic solvent.

[0129] [Organic Solvent] The organic solvent may be an aprotic solvent. The organic solvent may include one or more solvents selected from the group consisting of carbonate solvents, ether solvents, fluorine solvents, nitrile solvents, phosphate ester solvents, and sulfone solvents, and may include a carbonate 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 ether solvents 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 nitrile solvent include acetonitrile, succinonitrile, etc. Examples of the lactone solvent include γ-butyrolactone, etc.

[0134] Examples of phosphate ester solvents include trimethyl phosphate (TMP), triethyl phosphate (TEP), and tris(2,2,2-trifluoroethyl) phosphate (TFEP).

[0135] Examples of sulfonic acid solvents include sulfolane and 3-methylsulfolane.

[0136] Other examples of organic solvents include 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 a monocyclic or fused ring system). Only one organic solvent may be used, or a mixed solvent containing two or more organic solvents may be used.

[0137] The content of the organic solvent may be, for example, 10 to 1000 parts by mass, 50 to 800 parts by mass, 100 to 600 parts by mass, 150 to 600 parts by mass, or 200 to 500 parts by mass relative to 100 parts by mass of the second polymer contained in the quasi-solid electrolyte.

[0138] [Porous Material] The porous material may be a resin porous material. Specific examples of the porous material include a porous polyolefin membrane and a porous ceramic membrane.

[0139] [Film-forming additive] The film-forming additive 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 former. 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.

[0140] Examples of film-forming additives include carbonate compounds, aliphatic polyunsaturated compounds, aromatic compounds having vinyl groups, unsaturated ester compounds, unsaturated nitrile compounds, polyvalent ester 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, and electrolytic reduction-polymerizable compounds such as silanes, as well as electrolytic oxidation-polymerizable compounds such as pyrrole, aniline, thiophene, and derivatives thereof. The quasi-solid electrolyte may contain one or more film-forming additives.

[0141] 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 vinylene carbonate, vinylethylene carbonate, allylethyl carbonate, and fluoroethylene carbonate (4-fluoro-1,3-dioxane-2-one).

[0142] Examples of aliphatic polyunsaturated compounds include conjugated unsaturated compounds such as butadiene. Examples of aromatic compounds having a vinyl group include vinylpyridines such as 2-vinylpyridine, methyl cinnamate, and styrene. Examples of unsaturated ester compounds include (meth)acrylic acid esters and α-cyanoacrylic acid esters. Examples of unsaturated nitrile compounds include α,β-unsaturated nitrile compounds such as (meth)acrylonitrile. Examples of polyvalent ester compounds include dialkylmalonic acid ester compounds such as dimethylmalonic acid ester, diethylmalonic acid ester, di-n-hexylmalonic acid ester, and dicyclohexylmalonic acid ester. Examples of vinyl ester compounds of carboxylic acids include vinyl acetate and divinyl adipate. Examples of cyclic acid anhydrides include maleic anhydride. Examples of cyclic imide compounds 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. Examples of organic nitro compounds include nitro compounds having an ethylenically unsaturated group, such as nitroethylene (nitroethene).

[0143] Examples of sulfur-based compounds include SO ２Examples of sulfur dioxide (sulfur dioxide), polysulfides, sulfite ester compounds, sulfonate ester compounds, sulfate ester compounds, and sulfone compounds are included. The sulfonate ester compounds may be cyclic sulfonate ester compounds. Examples of sulfonate esters include 1,3-propane sultone, 1,4-butane sultone, 1,3-propene sultone, and 1,4-butene sultone. The sulfate ester compounds may be cyclic sulfate ester compounds. Examples of sulfate ester compounds include propylene sulfate, butylene sulfate, and ethylene propyl sulfate. Examples of sulfite ester compounds include cyclic alkyl sulfite ester compounds and aromatic (aryl) sulfite ester compounds. Examples of sulfite esters include ethylene sulfite and propylene sulfite. The sulfone compounds may be cyclic sulfone compounds. Examples of sulfone compounds include sulfolane, 3-methylsulfolane, 3-sulfolene, and 2-sulfolene.

[0144] Examples of boron compounds include B ２ O ３ (boron oxide), organic boron compounds, boroxine compounds, etc.

[0145] The film-forming additive may include at least one of vinylene carbonate and fluoroethylene carbonate.

[0146] The content of the film-forming additive in the quasi-solid electrolyte may be, for example, 0.01 to 100 parts by mass, 0.1 to 80 parts by mass, 1 to 50 parts by mass, 1 to 30 parts by mass, 3 to 25 parts by mass, or 5 to 20 parts by mass relative to 100 parts by mass of the second polymer.

[0147] The transference number of the alkali metal ion in the quasi-solid electrolyte may be, for example, 0.5 or more, 0.6 or more, or 0.7 or more. The transference number is the transference number measured at room temperature (25° C.).

[0148] The quasi-solid electrolyte can be produced, for example, by mixing a second polymer, an ionic compound, and particles. Other components, such as an organic solvent and a film-forming additive, may also be added. The quasi-solid electrolyte is typically formed into a film or pellets and used as a compact.

[0149] The battery according to the present embodiment may be, for example, 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 or a secondary battery. The battery may also be a solid-state battery.

[0150] Although several embodiments have been described above, the present disclosure is not limited to the above embodiments. Furthermore, the descriptions of the above embodiments can be applied to each other.

[0151] The present disclosure will be described in more detail below using examples and comparative examples, but the present disclosure is not limited to the following examples.

[0152] Example 1 [Synthesis of Monomer Represented by Formula (X)] A monomer represented by formula (X) was synthesized by the following method.

[0153]

[0154] First, chlorosulfonic acid (69 mL, 1.04 mol) was added to N-phenylmaleimide (30 g, 0.17 mol) at 0°C, and the mixture was stirred at 45 to 50°C for 1 hour. The resulting product was cooled to room temperature and poured onto ice. After stirring for a while, the precipitated crystals were collected by filtration and purified by silica gel column chromatography. The eluent used was a mixture of hexane and ethyl acetate in a volume ratio of 2 / 1 to 1 / 1. As a result of purification, 34 g (yield 73%) of an intermediate represented by the following formula was obtained. The resulting intermediate was a pale yellow solid.

[0155]

[0156] Next, under a nitrogen atmosphere, trifluoromethanesulfonamide (manufactured by Tokyo Chemical Industry Co., Ltd.) (4.22 g, 28.3 mmol) was dissolved in dehydrated acetonitrile (160 mL, manufactured by Kanto Chemical Co., Ltd.) to prepare a solution. To this solution, 1.0 equivalent of lithium carbonate relative to trifluoromethanesulfonamide, 2.0 equivalents of lithium hydroxide (manufactured by Tokyo Chemical Industry Co., Ltd.), and the intermediate synthesized as described above (6.9 g, 25.5 mmol) were added in that order, and the reaction was carried out at 0°C for 4.5 hours. After the temperature of the reaction solution was returned to room temperature, it was filtered, and the solvent was distilled off from the filtrate under reduced pressure. The residue was decanted with diethyl ether and dried under reduced pressure, yielding 10.5 g of monomer X as a pale brown solid.

[0157] [Synthesis of Copolymer 1] A copolymer of the monomer represented by formula (X) obtained as described above and styrene was synthesized by the following method. First, 0.558 g of the monomer represented by formula X, 0.149 g of styrene, and 11.7 mg of azobisisobutyronitrile were dissolved in 6.7 mL of dehydrated acetonitrile, and tetralin was further added as an internal standard substance. Next, the reaction was carried out for 24 hours at 60°C under a nitrogen atmosphere while checking the monomer consumption rate. After the reaction, the polymerization solution was dialyzed in acetonitrile and vacuum dried at 120°C to obtain 0.640 g (yield 87%) of Copolymer 1. The monomer introduction ratio was monomer X:styrene = 52:48. The monomer introduction ratio of the copolymer was １ The number average molecular weight of the copolymer was calculated from H-NMR. Mn = 9.4 × 10 ４ , weight average molecular weight Mw=4.2×10 ５ The number average molecular weight and the weight average molecular weight were measured by gel permeation chromatography.

[0158] The monomer introduction ratio in the obtained copolymer 1 was the monomer represented by formula (X):styrene=52:48. １ The number average molecular weight Mn of the copolymer 1 was calculated from H-NMR. ４ , weight average molecular weight Mw=4.2×10 ５The number average molecular weight and the weight average molecular weight were measured by gel permeation chromatography.

[0159] [Preparation of Positive Electrode Material 1] LiFePO ４ (LFP), copolymer 1 synthesized as described above, carbon nanotubes (average diameter 10 nm, multi-layer), and poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) were weighed and mixed at room temperature using a mortar and pestle in a mass ratio of 93.5:3:0.5:3 to obtain positive electrode material 1. The details of the positive electrode active material used are as follows. Nominal: LiFePO ４ Crystal structure: Pnma Average particle size: 1.0 μm

[0160] <Evaluation of properties of positive electrode material: porosity measurement> The porosity of the positive electrode material 1 prepared as described above was measured by mercury intrusion porosimetry. As a result, the ratio of pores having pore diameters of 0.1 to 100 μm to all pores (porosity) of the positive electrode material 1 was 25%. The measurement was performed by gradually increasing the pressure from 0.00689 MPa up to 413.7 MPa. The cumulative pore volume of the pores obtained when pressurized to 413.7 MPa was taken as the volume of all pores.

[0161] [Preparation of Quasi-Solid Electrolyte (Electrolyte Composition 1)] 25 parts by mass of the copolymer 1 was mixed with 75 parts by mass of a solution obtained by dissolving lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) in an amount of 50 mol% relative to 100 mol% of the structural unit (corresponding to the structural unit (A)) corresponding to the monomer represented by formula (X) in the copolymer 1. A gel-like polymer composition (gel polymer 1) was prepared by mixing them. The organic solvent used was a mixed solvent of ethylene carbonate (EC) and propylene carbonate (PC) (volume ratio 1:1) and fluoroethylene carbonate (FEC) in a mass ratio of 95:5.

[0162] 80 parts by mass of the gel polymer 1 prepared as described above, 20 parts by mass of fumed silica, and 3 parts by mass of polytetrafluoroethylene (PTFE) were weighed and mixed to obtain an electrolyte composition 1.

[0163] [Production of Battery] A battery was produced by laminating cathode material 1, electrolyte composition 1, and graphite in this order in a glove box adjusted to a dry argon atmosphere.

[0164] <Battery Evaluation: Charge / Discharge Test> The battery obtained as described above was used as an evaluation cell for the coin-type battery CR2032, and a charge / discharge test was performed. Specifically, using the evaluation cell, charge / discharge measurements were performed in a constant temperature bath at 60°C within a range of 2.5-4.0 V (vs. Li / Li+), and 10 cycles were performed at each current value. The capacity retention rate was calculated from the results of the first and tenth cycles. The results are shown in Table 1 and FIG. 1.

[0165] Example 2 A battery was fabricated in the same manner as in Example 1, except that lithium was used instead of graphite as the negative electrode. The fabricated battery was evaluated in the same manner as in Example 1. The results are shown in Table 1 and FIG. 2.

[0166] Example 3 Preparation of Quasi-Solid Electrolyte (Electrolyte Composition 3) 16.7 parts by mass of the copolymer 1, 8.3 parts by mass of PVdF-HFP, and a solution obtained by dissolving lithium hexafluorophosphate (LiPF6) in an amount of 25 mol% relative to 100 mol% of the structural unit (corresponding to the structural unit (A)) corresponding to the monomer represented by formula (X) in the copolymer 1 in 75 parts by mass of an organic solvent were mixed to prepare a gel polymer composition (gel polymer 2). The organic solvent used was a mixed solvent of ethylene carbonate (EC) and propylene carbonate (PC) (volume ratio 1:1) and fluoroethylene carbonate (FEC) mixed in a mass ratio of 95:5.

[0167] Electrolyte composition 3 was obtained by weighing out and mixing 70 parts by mass of gel polymer 2 prepared as described above, 30 parts by mass of alumina, and 3 parts by mass of polytetrafluoroethylene (PTFE).

[0168] [Production of Battery] A battery was produced in the same manner as in Example 2, except that electrolyte composition 3 was used instead of electrolyte composition 1. The obtained battery was used as an evaluation cell for the coin-type battery CR2032, and a charge-discharge test was carried out. Specifically, the evaluation cell was used to perform a charge-discharge test at 2.5-4.0 V (vs. Li / Li ＋ ) in a constant temperature bath at 60°C, and three cycles were performed at each current value. The results are shown in Table 1. In Example 3, only three cycles were performed, and therefore, "-" is indicated in Table 1. The capacity retention rate calculated from the results of the first and third cycles was 92%.

[0169] Comparative Example 1 Preparation of Quasi-Solid Electrolyte (Electrolyte Composition 2) 25 parts by mass of the copolymer 1 synthesized in Example 1, 12.5 parts by mass of poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), 2.8 parts by mass of lithium bis(trifluoromethanesulfonylimide) (LiTFSI), and 37.5 parts by mass of a fluoroethylene carbonate solution were mixed to obtain an electrolyte composition 2. The concentration of the fluoroethylene carbonate solution was 5% by mass, and the solution was prepared by dissolving fluoroethylene carbonate (manufactured by Kishida Chemical Co., Ltd.) in a mixed solvent (ethylene carbonate:propylene carbonate = 1:1 (volume ratio)).

[0170] [Fabrication of Battery] A battery was fabricated by laminating the positive electrode material 1, the electrolyte composition 2, and graphite in this order in a glove box adjusted to a dry argon atmosphere. The fabricated battery was evaluated in the same manner as in Example 1. The results are shown in Table 1 and FIG. 3.

[0171] Comparative Example 2 A battery was fabricated in the same manner as in Comparative Example 1, except that lithium was used instead of graphite as the negative electrode. The fabricated battery was evaluated in the same manner as in Example 1. The results are shown in Table 1 and FIG. 4.

[0172]

[0173] As shown in Table 1, it was confirmed that the batteries described in the examples, which combined a positive electrode having a specified porous structure according to the present disclosure with a quasi-solid electrolyte, had superior discharge capacity even at a discharge rate of 6 C, and also had high capacity retention and excellent cycle characteristics, compared to the batteries of the comparative examples which did not satisfy the above-mentioned requirements.

[0174] According to the present disclosure, a battery having a charge / discharge rate of 6 C or more and excellent cycle stability can be provided.

Claims

1. A battery having a positive electrode with a porous structure, a negative electrode, and a quasi-solid electrolyte disposed between the positive electrode and the negative electrode, wherein the positive electrode contains a first polymer and a conductive additive, and the ratio of pores having a pore size of 0.1 to 100 μm to the total pores is 23% or more as determined by mercury intrusion porosimetry, and the quasi-solid electrolyte contains a second polymer, an ionic compound, and particles.

2. The battery according to claim 1, wherein the ionic compound includes a lithium salt compound, and the content of the lithium salt compound is 0.1 to 3 equivalents per equivalent of the substance amount of lithium ions in the second polymer.

3. The battery according to claim 1 or 2, wherein the first polymer and the second polymer are polymers capable of preferentially conducting alkali metal ions.

4. The battery according to claim 1 or 2, wherein the positive electrode further comprises a positive electrode active material, the first polymer is a polymer capable of preferentially conducting alkali metal ions, and the content of the first polymer is 0.5 to 10 mass % relative to the total mass of the positive electrode, taken as 100 mass %.

5. The battery according to claim 1 or 2, wherein the conductive additive comprises fibrous carbon.

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