Polymer, electrolyte composition, and battery

Abstract

One aspect of the present disclosure provides a polymer which is represented by general formula (A). In general formula (A), X is a branch center, Poly is a polymer part that contains a structural unit B represented by general formula (B) and a structural unit C represented by general formula (C) at a specific ratio, and n is an integer of 3 or more. (In general formula (B), R1 to R4 are each independently a hydrogen atom or the like, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms; Y1 is a covalent bond, -O-, -S-, -NR10-, -(C= O)-, -(C=O)-O-, -O-(C=O)-, -(C=O)-NR11-, or -NR12-(C=O)-; R10, R11, and R12 are each independently a hydrogen atom or an organic group having 1 to 20 carbon atoms.) (In general formula (C), R5 and R6 are each independently a hydrogen atom, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms, or alternatively, one of R5 and R6 is a hydrogen atom, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms, and the other forms a ring together with Y2; R7 is a hydrogen atom, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms; Y2 is a divalent organic group having 1 to 20 carbon atoms, or forms a ring together with one of R5 and R6; Z- is an anionic functional group; and M is a lithium atom, a sodium atom, and a potassium atom.)

Description

Polymer, electrolyte composition, and battery

[0001] The present disclosure relates to polymers, electrolyte compositions, and 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] As lithium ion batteries and the like become more widespread, it is desirable to increase the range of polymer electrolytes to choose from depending on the environment in which they are used.

[0006] An object of the present disclosure is to provide a novel polymer that can be used as a polymer electrolyte. Another object of the present disclosure is to provide an electrolyte composition and a battery that include the polymer.

[0007] The present disclosure provides the following [1] to [9].

[0008] [1] General formula (A): In general formula (A), X is a branching center, Poly is a polymer portion, and n is an integer of 3 or more, the polymer portion contains a structural unit B represented by the following general formula (B) and a structural unit C represented by the following general formula (C), and the polymer portions each independently contain 20 to 80% of structural unit B and 20 to 80% of structural unit C based on the total structural units of each polymer portion. [In general formula (B), R １ ~R ４ are each independently a hydrogen atom, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms; Y １ is a covalent bond, -O-, -S-, -NR １０ -, -(C=O)-, -(C=O)-O-, -O-(C=O)-, -(C=O)-NR １１ - or -NR １２ -(C=O)-, and R １０ , R １１ and R １２ are each independently a hydrogen atom or an organic group having 1 to 20 carbon atoms. [In general formula (C), R ５ and R ６ are each independently a hydrogen atom, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms, or R ５ and R ６ One of the groups is a hydrogen atom, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms, and the other is Y ２ and form a ring together, and R ７ represents a hydrogen atom, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms; Y ２ is a divalent organic group having 1 to 20 carbon atoms, or R ５ and R ６ forms a ring with one of Z － is an anionic functional group, and M is a lithium atom, a sodium atom, or a potassium atom.] [2] The polymer according to [1], wherein X in the general formula (A) is a carbon atom, a nitrogen atom, a phosphorus atom, or a trivalent or higher organic group. [3] The polymer according to [1] or [2], wherein M in the structural unit C is a lithium atom or a sodium atom. [4] The polymer according to [1] or [2], wherein -Z in the structural unit C is － M ＋is a functional group selected from the group consisting of a lithiated sulfonic acid group, a lithiated carboxy group, and a lithiated sulfonylimide group. [5] An electrolyte composition comprising the polymer according to any one of [1] to [4]. [6] The electrolyte composition according to [5], further comprising an organic solvent. [7] The electrolyte composition according to [5], further comprising an alkali metal salt. [8] The electrolyte composition according to [5], further comprising an organic solvent and an alkali metal salt. [9] A battery comprising the electrolyte composition according to any one of [5] to [8].

[0009] According to the present disclosure, a novel polymer usable as a polymer electrolyte can be provided. According to the present disclosure, an electrolyte composition and a battery containing the polymer can also be provided.

[0010] Fig. 1 is a graph showing the evaluation results of DC current density for an evaluation cell using the electrolyte composition of Example 1. Fig. 2 is a graph showing the evaluation results of DC current density for an evaluation cell using the electrolyte composition of Example 2. Fig. 3 is a graph showing the evaluation results of DC current density for an evaluation cell using the electrolyte composition of Reference Example 1.

[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 alone 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] One embodiment of the polymer is a polymer represented by general formula (A): In the following general formula (A), X is a branching center, Poly is a polymer portion, and n is an integer of 3 or more.

[0014]

[0015] The polymer moiety in general formula (A) contains a structural unit B represented by the following general formula (B) and a structural unit C represented by the following general formula (C). The polymer moieties each independently contain 20 to 80% of the structural unit B and 20 to 80% of the structural unit C, based on the total structural units of each polymer moiety.

[0016] The polymer includes a structural unit C having an anionic functional group alkali-metallated with at least one alkali metal selected from the group consisting of lithium, sodium, and potassium in a polymer portion, and the polymer portions are connected via a branched structure, thereby increasing the free volume in the entire polymer and making the polymer chains in the polymer portion relatively mobile. This structure facilitates the movement of alkali metal ions, and can improve the transference number of alkali metal ions compared to a polymer having a structure corresponding to the polymer portion (a polymer without a branching center).

[0017] In general formula (A), X may be a carbon atom, a nitrogen atom, a phosphorus atom, or a trivalent or higher organic group. When X is a trivalent or higher organic group, where k is the valence of the organic group, n in general formula (A) is k or less. The valence k of the organic group may be, for example, 3 to 6, 3 to 5, 3, or 4. In general formula (A), n is an integer of 3 or greater, and may be 3 or 4. When n is 3, X may be, for example, a structure derived from a nitrogen atom, a phosphorus atom, tris(bromomethyl)benzene, or trivinylbenzene. When n is 4, X may be, for example, a carbon atom, or a structure derived from pentaerythritol.

[0018] In general formula (A), when X is a trivalent or higher organic group, X may be, for example, an organic group represented by the following formula (X1) or an organic group represented by the following formula (X2): In the following formulas (X1) and (X2), * represents a bonding site between each structural unit and another structural unit.

[0019]

[0020]

[0021] The polymer portion in general formula (A) contains a structural unit B represented by the following general formula (B) and a structural unit C represented by the following general formula (C). The polymer portion may further contain a structure derived from a chain transfer agent (for example, an -S(C=S)-S- group) at the end opposite the branch center X (the growth terminal side of the polymer portion). The polymer portions each independently contain 20 to 80% of structural unit B and 20 to 80% of structural unit C. In general formulas (B) and (C), * represents a structure derived from a chain transfer agent or a bonding portion between each structural unit and another structural unit.

[0022]

[0023]

[0024] In the above general formula (B), R １ ~R ４ Y each independently represents a hydrogen atom, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms. １ is a covalent bond, -O-, -S-, -NR １０ -, -(C=O)-, -(C=O)-O-, -O-(C=O)-, -(C=O)-NR １１ - or -NR １２ -(C=O)-, and R １０ , R １１ and R １２ are each independently a hydrogen atom or an organic group having 1 to 20 carbon atoms.

[0025] In the structural unit B, R １ ~R ４ are each independently a hydrogen atom, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms, and R １ ~R ４ is preferably a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms. １ , R ２ and R ３ At least two of R are preferably hydrogen atoms. １ , R ２ and R ３ It is more preferable that all of R are hydrogen atoms. １ ~R ４may all be hydrogen atoms.

[0026] In the structural unit B, R １ , R ２ and R ３ are each independently a monovalent organic group having 1 to 20 carbon atoms, the number of carbon atoms of the organic group may be, for example, 1 to 15, 1 to 10, 1 to 6, 1 to 5, 1 to 3, or 1. When the organic group has 3 or more carbon atoms, it may be a linear, branched, or cyclic hydrocarbon group, and is preferably a linear hydrocarbon group. The hydrocarbon group may be an aliphatic hydrocarbon group or an aromatic hydrocarbon group, and is preferably an aliphatic hydrocarbon group. R １ , R ２ and R ３ is a monovalent organic group having 1 to 20 carbon atoms, R １ , R ２ and R ３ may each independently be an alkyl group.

[0027] In the structural unit B, R ４ is a monovalent organic group having 1 to 20 carbon atoms, the number of carbon atoms of the organic group may be, for example, 2 to 20, 2 to 18, 3 to 15, 3 to 12, 4 to 10, 5 to 8, or 6 to 8. The organic group may be, for example, an alkyl group, an aryl group, or the like. When the number of carbon atoms constituting the alkyl group is 2 or more, the —CH ２ A portion of the - groups may be replaced with -O-, in which case the organic group may be an oxyalkylene group terminated with a hydrogen atom. When the organic group has 3 or more carbon atoms, it may be a linear, branched, or cyclic hydrocarbon group, with a branched hydrocarbon group being preferred. Examples of branched hydrocarbon groups include an isobutyl group. The aryl group may be, for example, a phenyl group.

[0028] In the structural unit B, Y １ is a covalent bond, -O-, -S-, -NR １０ -, -(C=O)-, -(C=O)-O-, -O-(C=O)-, -(C=O)-NR １１ - or -NR １２-(C=O)-, but is not a covalent bond, -O-, -S-, -(C=O)-O-, or -(C=O)-NR １１ It is preferable that −.

[0029] The above R １０ , R １１ and R １２ are each independently a hydrogen atom or an organic group having 1 to 20 carbon atoms. The number of carbon atoms in the organic group having 1 to 20 carbon atoms may be, for example, 1 to 18, 1 to 15, 1 to 10, 1 to 8, 1 to 6, 1 to 4, 1, or 2. The organic group may be linear, branched, or cyclic, and may be a linear aliphatic hydrocarbon group.

[0030] In the structural unit B, Y １ is a covalent bond, and R １ ~R ３ are all hydrogen atoms, and R ４ When Y is a phenyl group, the structural unit B can also be said to be a monomer unit when styrene is used as a monomer. １ is an oxygen atom, and R １ ~R ３ is a hydrogen atom, and R ４ is a branched aliphatic hydrocarbon having 4 carbon atoms, the structural unit B can also be said to be a monomer unit when isobutyl vinyl ether is used as a monomer.

[0031] In the above general formula (C), R ５ and R ６ each independently represents a hydrogen atom, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms, or R ５ and R ６ One of the groups is a hydrogen atom, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms, and the other is Y ２ It represents that the ring is formed together with R. ７ represents a hydrogen atom, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms. ２ represents a divalent organic group having 1 to 20 carbon atoms, or R ５ and R ６ It represents that a ring is formed with one of the two. － represents an anionic functional group, and M represents a lithium atom, a sodium atom, or a potassium atom.

[0032] The structural unit C is -Z － M ＋ The partial structure is a functional group having lithium ions, sodium ions, and potassium ions, and the polymer can conduct these alkali metal ions. － is an anionic functional group. In the structural unit C, M may be a lithium atom or a sodium atom.

[0033] -Z in structural unit C － M ＋ The partial structure represented by the formula (I) may be an alkali metal-modified functional group. In this specification, an alkali metal-modified functional group refers to a group in which an anionic functional group, which is a conjugate base of the acid form of the functional group, forms a salt with an alkali metal ion. Specific examples of the alkali metal-modified functional group include an alkali metal-modified phenolic hydroxyl group, an alkali metal-modified carboxylic acid group, an alkali metal-modified sulfonic acid group, and an alkali metal-modified sulfonylimide group. In this specification, an alkali metal refers to lithium, sodium, or potassium.

[0034] The alkali metal phenolic hydroxyl group is an —OM group (—O M group) in which H of the —OH group, which is a phenolic hydroxyl group, is substituted with an alkali metal element M. － M ＋ An alkali metal carboxylic acid group refers to a —COOM group ([—COO] group) in which H of a carboxylic acid group (—COOH group) is substituted with an alkali metal element M. － M ＋ The alkali metal sulfonic acid group refers to a sulfonic acid group (-SO ３ H group) in which H is substituted with an alkali metal element M ３ M group ([-SO ３ ] － M ＋ 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 M ２ -NM-SO ２ - group ([-SO ２ -N-SO ２ -] － M ＋ group), and examples thereof include a lithiated sulfonylimide group.

[0035] -Z in structural unit C － M ＋ The partial structure represented by the formula (I) may be, for example, a functional group selected from the group consisting of a lithiated phenol group, a lithiated sulfonic acid group, a lithiated carboxy group, and a lithiated sulfonylimide group, or may be a functional group selected from the group consisting of a lithiated sulfonic acid group, a lithiated carboxy group, and a lithiated sulfonylimide group.

[0036] In the structural unit C, R ５ and R ６ are each independently a hydrogen atom, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms, or R ５ and R ６ One of the groups is a hydrogen atom, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms, and the other is Y ２ In the structural unit C, R ５ and R ６ Of which Y ２ and R do not form a ring together with the structural unit C ５ and R ６ All of these are Y ２ When R does not form a ring together with ５ and R ６ In the structural unit C, R is preferably a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, and more preferably a hydrogen atom. ５ and R ６ At least one of R is preferably a hydrogen atom. ５ and R ６ It is more preferable that both of R and R are hydrogen atoms. ５ and R ６ Of which Y ２When they are taken together to form a ring, the atom not forming the ring is preferably a hydrogen atom.

[0037] In the structural unit C, Y ２ is a divalent organic group having 1 to 20 carbon atoms, or R ５ and R ６ It forms a ring with one of the Y ２ may have, for example, 1 to 15 carbon atoms, 2 to 10 carbon atoms, or 3 to 8 carbon atoms.

[0038] In the structural unit C, Y ２ is R ５ and R ６ When a ring is formed with one of the carbon atoms of the ethylene unit, it can be said that the ring is formed by bonding with two carbon atoms of the ethylene unit. The ring may be either a carbocyclic ring or a heterocyclic ring. The ring may also be either aliphatic or aromatic. Examples of heterocyclic rings include rings having an imide group, such as a maleimide ring.

[0039] Y ２ may be a divalent organic group having 1 to 20 carbon atoms, and may be an alkanediyl group, an arylene group, —O—, —S—, —NR ２０ -, -(C=O)-, -(C=O)-O-, -O-(C=O)-, -(C=O)-NR ２１ - or -NR ２２ It may be —(C═O)—.

[0040] The above R ２０ , R ２１ and R ２２ are each independently a hydrogen atom or an organic group having 1 to 20 carbon atoms. The number of carbon atoms in the organic group having 1 to 20 carbon atoms may be, for example, 1 to 18, 1 to 15, 1 to 10, 1 to 8, 1 to 6, 1 to 4, 1, or 2. The organic group may be linear, branched, or cyclic, and may be a linear aliphatic hydrocarbon group.

[0041] Above Y ２ is an alkanediyl group or an arylene group, the number of carbon atoms in the alkanediyl group and the arylene group may each be 1 to 20, 2 to 20, 2 to 20, 2 to 15, 2 to 10, 2 to 8, or 2 to 6. ２A part of the - group is -O-, -S-, or -NR ３０ -, -(C=O)-, -(C=O)-O-, -O-(C=O)-, -(C=O)-NR ３１ -, -NR ３２ It may be substituted with —(C═O)— or an arylene group.

[0042] The above R ３０ , R ３１ and R ３２ are each independently a hydrogen atom or an organic group having 1 to 20 carbon atoms. The number of carbon atoms in the organic group having 1 to 20 carbon atoms may be, for example, 1 to 18, 1 to 15, 1 to 10, 1 to 8, 1 to 6, 1 to 4, 1, or 2. The organic group may be linear, branched, or cyclic, and may be a linear aliphatic hydrocarbon group.

[0043] The structural unit C may be, for example, a structural unit C1 represented by the following general formula (C1): In general formula (C1), * represents a structure derived from a chain transfer agent or a position where the structural unit C1 is bonded to another structural unit.

[0044]

[0045] In general formula (C1), R ５ , and R ７ Y each independently represents a hydrogen atom, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms. ３ represents a trivalent organic group having 1 to 20 carbon atoms. － represents an anionic functional group, and M represents a lithium atom, a sodium atom, or a potassium atom.

[0046] In the structural unit C1, R ５ and R ７ are each independently a hydrogen atom, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms, and R ５ and R ７ is preferably a hydrogen atom or a monovalent organic group having 1 to 20 carbon atoms, and more preferably a hydrogen atom. ５ and R ７ At least one of R is preferably a hydrogen atom. ５ and R ７It is more desirable that both of the following are hydrogen atoms. In the structural unit C1, the monovalent organic group having 1 to 20 carbon atoms may be, for example, an alkyl group.

[0047] In the structural unit C1, Y ３ is a trivalent organic group having 1 to 20 carbon atoms. ３ is bonded to two carbon atoms of the ethylene unit to form a ring. The ring may be either a carbocyclic ring or a heterocyclic ring. The ring may be either an aliphatic ring or an aromatic ring. Examples of heterocyclic rings include rings having an imide group such as a maleimide ring. ３ may have, for example, 1 to 20 carbon atoms, 1 to 15 carbon atoms, 2 to 10 carbon atoms, or 3 to 8 carbon atoms.

[0048] The structural unit C1 may be a group containing a maleimide ring having an alkali metal group, and specifically may be, for example, a structural unit C2 represented by the following general formula (C2): In general formula (C2), * represents a structure derived from a chain transfer agent or a position at which the structural unit C2 is bonded to another structural unit.

[0049]

[0050] In general formula (C2), R ８ represents a divalent organic group having 1 to 20 carbon atoms. ９ represents a halogen atom or a monovalent organic group having 1 to 20 carbon atoms. ＋ represents an alkali metal ion.

[0051] R in structural unit C2 ８ The number of carbon atoms in R may be, for example, 1 to 15, 2 to 10, or 3 to 8. ８ When 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 may be a phenylene group or a substituted phenylene group. A substituted phenylene group means a phenylene group in which at least some of the constituent elements have been substituted with an alkyl group, a halogen atom, an electron-withdrawing group, or the like.

[0052] R in structural unit C2 ９ is a monovalent organic group, R ９ The number of carbon atoms in the structural unit C2 may be, for example, 1 to 15, 1 to 10, 1 to 8, 1 to 5, or 1 to 3. ９ When R 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. ９ When is a halogen atom, the halogen atom may be a fluorine atom or a chlorine atom, and may be a fluorine atom.

[0053] The polymer portion in the polymer is a copolymer chain containing the structural unit B and the structural unit C in a predetermined ratio, but may contain structural units other than the structural unit B and the structural unit C. The polymer portion may be composed only of monomer units containing at least the structural unit B and the structural unit C, or may be composed only of a structure and monomer units derived from a chain transfer agent. The monomer units preferably consist only of the structural unit B and the structural unit C.

[0054] The plurality of structural units B present in the polymer portion may be structural units that independently satisfy the requirements of general formula (B), and the plurality of structural units C present in the polymer portion may be structural units that independently satisfy the requirements of general formula (C). However, from the viewpoint of ease of production, it is desirable that the plurality of structural units B present in the polymer be the same structural unit, and it is desirable that the plurality of structural units C present in the polymer be the same structural unit. The polymer portion may have a region in which the structural units B and the structural units C are alternately arranged, or may be a random copolymer. It is preferable that the polymer portion does not contain a block structure of the structural unit B.

[0055] In the polymer portion, the proportion of the structural unit B is 20 to 80% based on the total structural units of each polymer portion, but may be, for example, 25 to 75%, 30 to 70%, 35 to 65%, or 40 to 60%.

[0056] In the polymer portion, the proportion of the structural unit C is 20 to 80% based on the total structural units of each polymer portion, but may be, for example, 25 to 75%, 30 to 70%, 35 to 65%, or 40 to 60%.

[0057] In this specification, the ratio of structural units in each polymer portion (monomer introduction ratio) is the ratio of the number of each structural unit in the polymer to the number of all structural units, and is １ It can be determined by H-NMR measurement.

[0058] 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 polymer (A) 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.

[0059] The number average molecular weight and weight average molecular weight of the polymer in this specification can be measured by gel permeation chromatography (GPC) performed under the following conditions. For preparing a calibration curve, a standard sample of polymethyl methacrylate (manufactured by Polymer Laboratories, Mn 800 to 2,200,000) is used as the standard substance. <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

[0060] The above-mentioned polymer may be obtained by a chain transfer reaction of monomers having polymerizable functional groups corresponding to the structural unit B and the structural unit C in the presence of a chain transfer agent (RAFT agent) having a branching center X structure. The polymerization method may be, for example, RAFT polymerization. Examples of the monomer corresponding to the structural unit B include styrene and isobutyl vinyl ether. Examples of the monomer corresponding to the structural unit C include -Z － M ＋ and N-substituted maleimides having a partial structure represented by the following formula:

[0061] Electrolyte Composition One embodiment of the electrolyte composition includes the polymer described above.

[0062] The electrolyte composition may contain other components in addition to the polymer. Examples of the other components include organic solvents, alkali metal salts, other resins (binder resins, etc.) such as fluorine-based resins, fabrics such as nonwoven fabrics, porous materials, and viscosity adjusters. The electrolyte composition may contain an organic solvent and an alkali metal salt, or may contain an organic solvent, an alkali metal salt, and a fluorine-based resin.

[0063] (Organic Solvent) Examples of the organic solvent include aprotic solvents. 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, phosphate-based solvents, and sulfone-based solvents, and may include a carbonate-based solvent.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] Examples of the nitrile solvent include acetonitrile, succinonitrile, etc. Examples of the lactone solvent include γ-butyrolactone, etc.

[0068] Examples of phosphate ester solvents include trimethyl phosphate (TMP), triethyl phosphate (TEP), and tris(2,2,2-trifluoroethyl) phosphate (TFEP).

[0069] Examples of sulfonic acid solvents include sulfolane and 3-methylsulfolane.

[0070] 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.

[0071] 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 polymer contained in the electrolyte composition.

[0072] (Alkali Metal Salt) The alkali metal salt may be in either a solid or liquid form. The alkali metal salt may be an ionic liquid. The ionic liquid may be, for example, an alkali metal salt dissolved in a polyether such as tetraethylene glycol dimethyl ether (tetraglyme).

[0073] The alkali metal salts include, for example, 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 F ２ｉ＋１ ) SO ２ ]} (h and i are 0 to 3), and MBOB (BOB is bisoxalatoborate).

[0074] The alkali metal element M in the alkali metal salt is not particularly limited as long as it is an element classified as an alkali metal, and may contain, for example, lithium, sodium, or potassium, or may contain lithium or sodium, or may contain lithium. The alkali metal salt may be a lithium salt compound. The alkali metal element contained in the alkali metal salt may be the same as the alkali metal element in the structural unit B contained in the polymer.

[0075] The content of the alkali metal salt in the electrolyte composition 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 the alkali metal ions contained in the alkali metal salt relative to the total amount of the structural unit C contained in the polymer.

[0076] The content of the lithium salt compound may be, for example, 0.05 to 3.0 equivalents, 0.1 to 2.5 equivalents, 0.2 to 2.0 equivalents, or 0.5 to 1.5 equivalents relative to 1 equivalent of the substance amount of lithium ions in the polymer.

[0077] (Fluorine-based resin) The fluorine-based resin 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 fluorine-based resin include polytetrafluoroethylene (PTFE), poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP), and polyvinylidene fluoride (PVDF).

[0078] The content of the fluororesin may be 10 to 200 parts by mass, or 50 to 150 parts by mass, relative to 100 parts by mass of the polymer. The content of the fluororesin may be, for example, 0.1 to 20% by mass, 0.1 to 10% by mass, or 0.1 to 5% by mass, relative to the total amount of the electrolyte composition.

[0079] An example of a method for producing an electrolyte composition includes mixing a polymer and an organic solvent. At this time, other components such as an alkali metal salt and a fluorine-based resin may be added. The electrolyte composition may be formed into a film or pellets and used as a molded product.

[0080] The electrolyte composition of this embodiment can be used, for example, as a composition for forming an electrolyte in a battery, a capacitor, or the like. That is, one embodiment of a battery or capacitor has an electrolyte, and the electrolyte may include the above-described electrolyte composition. Examples of the battery include batteries that charge and discharge by the movement of alkali metal ions, such as lithium ion batteries and sodium ion batteries. The battery may be a primary battery, a secondary battery, or a solid-state battery. The electrolyte composition of this embodiment may be used as an electrode material and may be contained in at least one of the positive electrode and the negative electrode.

[0081] [Battery] One embodiment of a battery includes the above-described polymer or the above-described electrolyte composition. The battery of this embodiment includes a positive electrode, a negative electrode, and an electrolyte disposed between the positive electrode and the negative electrode, and the electrolyte may include the above-described polymer or the above-described electrolyte composition. The electrolyte may be formed by disposing the polymer or the electrolyte composition of this embodiment between the positive electrode and the negative electrode.

[0082] The positive electrode may be a layer containing a positive electrode material formed on a current collector, and the negative electrode may be a layer containing a negative electrode material formed on a current collector.

[0083] Furthermore, when the electrolyte composition contains an organic solvent, an interface can be more easily formed between the electrodes (positive electrode and negative electrode) and the electrolyte. In other words, the electrolyte composition may contain an organic solvent to form an interface between at least one of the positive electrode and the electrolyte and the negative electrode and the electrolyte. Hereinafter, the battery according to this embodiment will be described using a lithium ion battery as an example.

[0084] The positive electrode includes a positive electrode active material. The positive electrode active material is not particularly limited, and examples thereof include lithium composite metal oxides containing lithium and a transition metal element. The transition metal element may be at least one element selected from the group consisting of V, Cr, Mn, Fe, Co, Ni, Cu, and Al, and may contain Ni. Examples of lithium composite metal oxides include LiCoO ２ , LiNiO ２ , LiMn ２ O４ , 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 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.

[0085] The positive electrode may contain, for example, a conductive additive, a binding resin (binder), and the like, as needed.

[0086] The negative electrode includes a negative electrode active material, such as a simple 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.

[0087] The negative electrode may contain, for example, a conductive additive, a binding resin (binder), and the like, as needed.

[0088] The battery may have a separator. The separator may be, for example, a porous material. The porous material may be, for example, a resin porous material. Specific examples of resin porous materials include porous polyolefin membranes and porous ceramic membranes.

[0089] 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.

[0090] The present disclosure will be described in more detail below using examples, comparative examples, and reference examples, but the present disclosure is not limited to the following examples.

[0091] Example 1 Synthesis of Monomer D Monomer D represented by the following formula (D) was synthesized by the following method.

[0092]

[0093] First, N-phenylmaleimide (30 g, 0.17 mol) and chlorosulfonic acid (69 mL, 1.04 mol) were added to a reactor at 0°C and stirred at 45-50°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.

[0094]

[0095] Next, under a nitrogen atmosphere, trifluoromethanesulfonamide (manufactured by Tokyo Chemical Industry Co., Ltd.) (4.22 g, 28.3 mmol) was dissolved in dehydrated acetonitrile (120 mL, manufactured by Kanto Chemical Co., Ltd.) to prepare a solution. To this solution, 1.0 equivalent of lithium carbonate (2.09 g, 28.3 mmol) relative to trifluoromethanesulfonamide, 2.0 equivalents of lithium hydroxide (manufactured by Tokyo Chemical Industry Co., Ltd.) (1.36 g, 56.6 mmol), and the intermediate synthesized as described above (7.00 g, 25.8 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, resulting in 10.5 g of monomer D as a pale brown solid.

[0096] [Synthesis of Chain Transfer Agent] A tetrafunctional chain transfer agent A was synthesized by the following reaction.

[0097]

[0098] Under a nitrogen atmosphere, pentaerythritol (5.00 g, 36.7 mmol, 1.0 eq.), tetrahydrofuran (THF, 160 mL), and triethylamine (Et ３ N (23.1 mL, 166 mmol, 4.5 eq.) was measured out to prepare a mixed solution. Next, under ice-cooling, a solution of 2-bromopropionylbromide (17.3 mL, 165 mmol, 4.5 eq.) in THF (65 mL) was added dropwise to the mixed solution, and after the dropwise addition, the mixture was stirred overnight at room temperature. Water was added to the reaction solution, and the mixture was extracted with ethyl acetate (AcOEt). The organic layer was extracted with saturated sodium bicarbonate (NaHCO ３ ) aqueous solution and water, and ４ The crude product was dried using a filtration membrane. After removing the magnesium sulfate, the filtrate was concentrated. The crude product was recrystallized in diisopropyl ether (IPE) to obtain a colorless solid, precursor A of the tetrafunctional chain transfer agent (6.23 g, 25%).

[0099] Next, under a nitrogen atmosphere, 1-butanethiol (6.65 g, 73.8 mmol, 8.0 eq.), THF (216 mL), and Et ３ Then, carbon disulfide (CS) was added to the solution under ice cooling. ２ , 4.51 mL, 74.7 mmol, 8.1 eq.) was added dropwise to the above mixed solution, and after the dropwise addition, the mixture was stirred at room temperature for 2 hours. The reaction solution was cooled on ice, and a solution of precursor A (6.23 g, 9.22 mmol, 1.0 eq.) prepared as above in THF (86.0 mL) was added dropwise, and the mixture was stirred at room temperature overnight. The reaction solution was concentrated, and dichloromethane was added, followed by washing with a 10% aqueous HCl solution and water, successively. The organic layer was separated using anhydrous magnesium sulfate (MgSO ４ ) was used for drying. After removing the magnesium sulfate, the filtrate was concentrated. The resulting crude product was purified by column chromatography (developing solvent: hexane / AcOEt = 9 / 1) to obtain tetrafunctional chain transfer agent A (5.60 g, 60%) as a yellow liquid.

[0100] [Synthesis of Copolymer (Polymer 1)] A copolymer was synthesized using pentaerythritol as the tetrafunctional branching center by the method described below. First, 2,2'-azobis(isobutyronitrile) (Tokyo Chemical Industry Co., Ltd., 2.8 mg, 17 μmol) and chain transfer agent A (83.7 mg, 82.3 μmol) prepared as described above were added to a reaction vessel, and the vessel was cooled to -78°C in dry ice methanol. An argon atmosphere was created by repeatedly evacuating and supplying argon three times. Next, isobutyl vinyl ether (1.3 mL, 10 mmol) and a deoxygenated acetonitrile solution of monomer D (133 mM, 15.0 mL, 2.00 mmol) prepared as described above were added, and the mixture was stirred at 60°C for 24 hours to carry out RAFT polymerization. The polymerization solution was returned to room temperature and then purified by dialysis three times in acetonitrile. The solution in the dialysis membrane was recovered, the acetonitrile was distilled off, and the resulting solution was vacuum dried overnight at 80° C. to synthesize a copolymer having a branched structure (hereinafter also referred to as polymer 1). The isobutyl vinyl ether used was prepared by washing commercially available isobutyl vinyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) with a 10% aqueous sodium hydroxide solution and then with ion-exchanged water, separating and purifying the solution, drying it overnight over calcium chloride, filtering it, and further adding calcium hydride and distilling it.

[0101] [Production of Electrolyte Composition] A mixture of 100 parts by mass of the copolymer (Polymer 1) and 50 parts by mass of PVdF-HFP (poly(vinylidene fluoride-co-hexafluoropropylene)) was mixed with 300 parts by mass of an organic solvent to prepare a gel-like electrolyte composition. The organic solvent used was a mixed solvent of ethylene carbonate (EC) and propylene carbonate (PC) (volume ratio 1:1).

[0102] Example 2 Synthesis of Chain Transfer Agent Trifunctional chain transfer agent B was synthesized by the following reaction.

[0103]

[0104] Under a nitrogen atmosphere, 1-butanethiol (4.55 g, 50.5 mmol, 4.5 eq.), tripotassium phosphate (K ３ P.O. ４, 10.7 g, 50.4 mmol, 4.5 eq.) and acetone (120 mL) were weighed out to prepare a mixed solution. ２ , 9.13 mL, 151 mmol, 13.5 eq.) was added dropwise to the above mixed solution, and after the dropwise addition, the mixture was stirred at the same temperature for 1 hour and then at room temperature overnight. The reaction solution was cooled on ice, and a solution of 1,3,5-tris(bromomethyl)benzene (4.00 g, 11.2 mmol, 1.0 eq.) in acetone (30 mL) was added dropwise, and the mixture was stirred at room temperature overnight. Water was added to the reaction solution, and the mixture was extracted with dichloromethane. The organic layer was washed with water, and anhydrous magnesium sulfate (MgSO ４ After removing the magnesium sulfate, the filtrate was concentrated. The crude product was purified by column chromatography (eluent: hexane / CH ２ Cl ２ = 100 / 0 → 1 / 1) to give trifunctional chain transfer agent B (5.30 g, 77%) as a yellow liquid.

[0105] [Synthesis of Copolymer (Polymer 2)] A copolymer was synthesized using trivinylbenzene as the trifunctional branching center by the method described below. First, 2,2'-azobis(isobutyronitrile) (Tokyo Chemical Industry Co., Ltd., 1.4 mg, 8.5 μmol) and the chain transfer agent B (22.4 mg, 36.5 μmol) prepared as described above were added to a reaction vessel, and the vessel was cooled to -78°C with dry ice methanol. An argon atmosphere was then created by evacuating and supplying argon three times. Next, dehydrated tetrahydrofuran (Wako Pure Chemical Industries, Ltd., 1.8 mL) was added and dissolved. A deoxygenated acetonitrile solution of monomer D (138 mM, 7.2 mL, 0.99 mmol) prepared as described above and styrene (0.11 mL, 0.96 mmol) were added, and the mixture was stirred at 60°C for 26.5 hours to carry out RAFT polymerization. The polymerization solution was returned to room temperature under aerobic conditions and then purified by dialysis three times in acetonitrile. The solution in the dialysis membrane was recovered, the acetonitrile was distilled off, and the resulting solution was vacuum dried overnight at 80° C. to synthesize a copolymer having a branched structure (hereinafter also referred to as polymer 2). The styrene used was obtained by drying commercially available styrene (manufactured by Tokyo Chemical Industry Co., Ltd.) overnight over calcium chloride, filtering, adding calcium hydride, and distilling under reduced pressure.

[0106] [Production of Electrolyte Composition] A gel-like electrolyte composition was prepared in the same manner as in Example 1, except that Polymer 2 was used as the copolymer instead of Polymer 1.

[0107] Example 3 [Synthesis of Copolymer (Polymer 3)] A copolymer was synthesized using pentaerythritol as the tetrafunctional branching center by the method described below. First, 2,2'-azobis(isobutyronitrile) (Tokyo Chemical Industry Co., Ltd., 1.5 mg, 9.1 μmol) and chain transfer agent A (38.6 mg, 37.9 μmol) prepared as described above were added to a reaction vessel, and the vessel was cooled to -78°C with dry ice methanol. An argon atmosphere was created by evacuating and supplying argon three times. A deoxygenated acetonitrile solution of monomer D (138 mM, 7.2 mL, 0.99 mmol) prepared as described above and styrene (0.11 mL, 0.96 mmol) were added to the vessel, and the mixture was stirred at 60°C for 26.5 hours to carry out RAFT polymerization. The polymerization solution was returned to room temperature under aerobic conditions and then purified by dialysis three times in acetonitrile. The solution in the dialysis membrane was recovered, the acetonitrile was distilled off, and the resulting mixture was vacuum dried overnight at 80° C. to synthesize a copolymer having a branched structure (hereinafter also referred to as polymer 3). The styrene used was obtained by drying commercially available styrene (manufactured by Tokyo Chemical Industry Co., Ltd.) overnight over calcium chloride, filtering, adding calcium hydride, and distilling under reduced pressure.

[0108] [Production of Electrolyte Composition] A gel-like electrolyte composition was prepared in the same manner as in Example 1, except that Polymer 3 was used as the copolymer instead of Polymer 1.

[0109] Example 4 Production of Electrolyte Composition A mixture of 100 parts by mass of the copolymer (polymer 3) prepared in the same manner as in Example 3 and 50 parts by mass of PVdF-HFP (poly(vinylidene fluoride-co-hexafluoropropylene)) was further mixed with 400 parts by mass of [Li(G4)][FSI] (an ionic liquid obtained by dissolving equimolar amounts of lithium-bis(fluorosulfonyl)imide (LiFSI) in tetraglyme (dimethoxytetraethylene glycol)) as an alkali metal salt and 100 parts by mass of an organic solvent to prepare a gel-like electrolyte composition. A mixed solvent (volume ratio 1:1) of ethylene carbonate (EC) and propylene carbonate (PC) was used as the organic solvent.

[0110] Example 5 [Synthesis of Copolymer (Polymer 4)] A copolymer was synthesized using trivinylbenzene as the trifunctional branching center by the method described below. First, 2,2'-azobis(isobutyronitrile) (Tokyo Chemical Industry Co., Ltd., 2.9 mg, 17 μmol) and the chain transfer agent B (51.2 mg, 83.5 μmol) prepared as described above were added to a reaction vessel, and the vessel was cooled to -78°C with dry ice methanol while evacuating and supplying argon three times to create an argon atmosphere. Next, anhydrous tetrahydrofuran (Wako Pure Chemical Industries, Ltd., 3.5 mL) was added and dissolved, and then isobutyl vinyl ether (1.3 mL, 10 mmol) and a deoxygenated acetonitrile solution of monomer D (133 mM, 15.0 mL, 2.00 mmol) prepared as described above were added. RAFT polymerization was carried out by stirring at 60°C for 24 hours. The polymerization solution was returned to room temperature under aerobic conditions and then purified by dialysis three times in acetonitrile. The solution in the dialysis membrane was recovered, the acetonitrile was distilled off, and the resulting solution was vacuum dried overnight at 80° C. to synthesize a copolymer having a branched structure (hereinafter also referred to as polymer 4). The isobutyl vinyl ether used was prepared by washing commercially available isobutyl vinyl ether (manufactured by Tokyo Chemical Industry Co., Ltd.) with a 10% aqueous sodium hydroxide solution and then with ion-exchanged water, separating and purifying the solution, drying it overnight over calcium chloride, filtering it, and further adding calcium hydride and distilling it.

[0111] [Production of Electrolyte Composition] A mixture of 100 parts by mass of the copolymer (polymer 4) and 50 parts by mass of PVdF-HFP (poly(vinylidene fluoride-co-hexafluoropropylene)) was further mixed with 400 parts by mass of [Li(G4)][FSI] (an ionic liquid obtained by dissolving equimolar amounts of lithium-bis(fluorosulfonyl)imide (LiFSI) in tetraglyme (dimethoxytetraethylene glycol)) as an alkali metal salt, and 100 parts by mass of an organic solvent to prepare a gel-like electrolyte composition. Note that a mixed solvent of ethylene carbonate (EC) and propylene carbonate (PC) (volume ratio 1:1) was used as the organic solvent.

[0112] Comparative Example 1 Synthesis of Copolymer (Polymer 5) 0.558 g of the monomer D obtained as described above, 0.149 g of styrene, and 11.7 mg of azobisisobutyronitrile were dissolved in 6.7 mL of dehydrated acetonitrile, and the reaction was carried out at 60°C for 24 hours under a nitrogen atmosphere while checking the monomer consumption rate by adding tetralin as an internal standard substance. The polymerization solution was dialyzed in acetonitrile and vacuum dried at 120°C to obtain 0.640 g (yield 87%) of copolymer (Polymer 5). The monomer introduction ratio was monomer D:styrene = 52:48. The monomer introduction ratio was 0.640 g (yield 87%) of copolymer (Polymer 5). １ The number average molecular weight of the copolymer (polymer 5) 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.

[0113] [Production of Electrolyte Composition] A gel-like electrolyte composition was prepared in the same manner as in Example 1, except that Polymer 5 was used as the copolymer instead of Polymer 1.

[0114] Comparative Example 2 Synthesis of Copolymer (Polymer 6) 0.741 g of Monomer D, 0.340 g of isobutyl vinyl ether, and 8.2 mg of azobisisobutyronitrile were dissolved in 10 mL of dehydrated acetonitrile, and the mixture was reacted at 60°C for 24 hours under a nitrogen atmosphere while checking the monomer consumption rate by adding tetralin as an internal standard substance. The polymerization solution was dialyzed in acetonitrile and vacuum dried at 120°C to obtain 0.34 g (yield 82%) of Copolymer (Polymer 6). The monomer introduction ratio was Monomer D:Isobutyl vinyl ether = 52:48. The monomer introduction ratio was 0.34 g (yield 82%) of Copolymer (Polymer 6). １ The number average molecular weight of the copolymer (polymer 6) was calculated from H-NMR. ４ , weight average molecular weight Mw=2.9×10 ４ The number average molecular weight and the weight average molecular weight were measured by gel permeation chromatography.

[0115] [Production of Electrolyte Composition] A gel-like electrolyte composition was prepared in the same manner as in Example 4, except that Polymer 6 was used as the copolymer instead of Polymer 3.

[0116] Reference Example 1 A gel electrolyte composition was prepared by mixing 100 parts by mass of polyethylene oxide (PEO), 200 parts by mass of an organic solvent, and 5 mol % of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) relative to 100 mol % of the ethylene oxide unit of PEO. The organic solvent used was a mixed solvent of ethylene carbonate (EC) and propylene carbonate (PC) (volume ratio 1:1).

[0117] <Evaluation of Electrolyte Compositions> For each of the electrolyte compositions prepared in Examples 1 to 5, Comparative Examples 1 and 2, and Reference Example 1, the maximum DC current density was measured by the method described below. The results are shown in Table 1. For reference, graphs showing the evaluation results of DC current density for evaluation cells using the electrolyte compositions of Examples 1, 2, and Reference Example 1 are shown in Figures 1, 2, and 3, respectively.

[0118] [Measurement of Maximum DC Current Density] An evaluation cell of the coin-type battery CR2032 was assembled in a glove box under a dry argon atmosphere. Specifically, first, each layer was stacked in the evaluation cell in the order of lithium / electrolyte composition / lithium to prepare a test laminate A. Hereinafter, the evaluation cell including the test laminate A will be referred to as evaluation cell A.

[0119] In Examples 1 to 5 and Comparative Examples 1 and 2, the evaluation cell A was alternately supplied with a current of 0.02 mA / cm in the positive and negative directions. ２ , 0.1mA / cm ２ , 0.2mA / cm ２ , 0.3mA / cm ２ , 0.4mA / cm ２ , 0.5mA / cm ２ , 0.6mA / cm ２ , 0.7mA / cm ２ , 0.8mA / cm ２ , 0.9mA / cm ２ , 1.0mA / cm ２ , 1.1mA / cm２ , and 1.2 mA / cm ２ A constant current test was carried out in which current densities of 10 and 11 were applied in this order for 10 cycles, and the test was terminated when the voltage reached 1.5 V. The maximum current density that could be applied before the voltage reached 1.5 V was defined as the maximum DC current density.

[0120] For Reference Example 1, 0.02 mA / cm ２ , 0.1mA / cm ２ , 0.2mA / cm ２ , 0.4mA / cm ２ , 0.6mA / cm ２ A constant current test was carried out by applying 5 cycles of DC current, 1.0 V, and 2.0 V in this order, and the test was terminated when the voltage reached 1.5 V. The maximum current density that could be applied before the voltage reached 1.5 V was defined as the maximum DC current density.

[0121] [Measurement of Lithium Ion Transference Number] The lithium ion transference numbers were measured by the method described below for the electrolyte compositions prepared in Examples 4 and 5, Comparative Example 2, and Reference Example 1. The results are shown in Table 1.

[0122] The lithium ion transport number was measured for the evaluation cell A. The lithium ion transport number was measured by first applying 10 mV to the evaluation cell A at room temperature (25° C.) and measuring the initial current value (I ０ ) and steady-state current value (I ｓｓ Next, the lithium ion transport number (t Ｌｉ＋ ) was calculated. Ｌｉ＋ =I ｓｓ / I ０

[0123]

[0124] As shown in Table 1, it was confirmed that the electrolyte compositions (Examples 1 to 3) using polymers 1 to 3 satisfying the requirements for the polymer according to the present disclosure were superior in maximum DC current density compared to the conventional electrolyte composition using a mixture of PEO and an alkali metal salt (Reference Example 1) and the electrolyte composition using unbranched polymer 5 (Comparative Example 1), and were fully useful as electrolytes. Furthermore, as shown in Table 1, it was confirmed that the electrolyte compositions (Examples 4 and 5) using polymer 3 or polymer 4 satisfying the requirements for the polymer according to the present disclosure in combination with an alkali metal salt were superior in lithium ion transport number and maximum DC current density compared to the electrolyte composition using unbranched polymer 6 and an alkali metal salt (Comparative Example 2).

[0125] According to the present disclosure, a novel polymer usable as a polymer electrolyte can be provided. According to the present disclosure, an electrolyte composition and a battery containing the polymer can also be provided.

Claims

1. General formula (A): In general formula (A), X is a branching center, Poly is a polymer portion, and n is an integer of 3 or more, the polymer portion contains a structural unit B represented by the following general formula (B) and a structural unit C represented by the following general formula (C), and the polymer portions each independently contain 20 to 80% of structural unit B and 20 to 80% of structural unit C based on the total structural units of each polymer portion. [In general formula (B), R １ ~R ４ are each independently a hydrogen atom, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms; Y １ is a covalent bond, -O-, -S-, -NR １０ -, -(C=O)-, -(C=O)-O-, -O-(C=O)-, -(C=O)-NR １１ - or -NR １２ -(C=O)-, and R １０ , R １１ and R １２ are each independently a hydrogen atom or an organic group having 1 to 20 carbon atoms. [In general formula (C), R ５ and R ６ are each independently a hydrogen atom, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms, or R ５ and R ６ One of the groups is a hydrogen atom, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms, and the other is Y ２ and form a ring together, and R ７ represents a hydrogen atom, a halogen atom, or a monovalent organic group having 1 to 20 carbon atoms; Y ２ is a divalent organic group having 1 to 20 carbon atoms, or R ５ and R ６ forms a ring with one of the － is an anionic functional group, and M is a lithium atom, a sodium atom, or a potassium atom.

2. The polymer according to claim 1, wherein X in the general formula (A) is a carbon atom, a nitrogen atom, a phosphorus atom, or a trivalent or higher organic group.

3. The polymer according to claim 1 or 2, wherein in the structural unit C, M is a lithium atom or a sodium atom.

4. -Z in the structural unit C － M ＋ The polymer according to claim 1 or 2, wherein the partial structure represented by the following formula (I) is a functional group selected from the group consisting of a lithiated sulfonic acid group, a lithiated carboxy group, and a lithiated sulfonylimide group.

5. An electrolyte composition comprising the polymer according to claim 1 or 2.

6. The electrolyte composition of claim 5, further comprising an organic solvent.

7. The electrolyte composition of claim 5, further comprising an alkali metal salt.

8. The electrolyte composition of claim 5, further comprising an organic solvent and an alkali metal salt.

9. A battery comprising the electrolyte composition of claim 5.

Images