Ionic gel, method for manufacturing the same, coating material, negative electrode, and metal secondary battery using the same

Abstract

To provide an ion gel with superior strength and ionic conductivity, a method for producing the same, a coating material, a negative electrode, and a metal secondary battery including the same.SOLUTION: An ion gel is prepared by polymerizing a composition including a radical polymerizable compound with ionic liquid. The radical polymerizable compound at least includes a hydrogen-binding monomer. The ionic liquid at least includes a solvation ionic liquid. The hydrogen-binding monomer is contained in the radical polymerizable compound at a molar fraction of 15% or more. The ratio of the mass of the radical polymerizable compound to the total mass of the ionic liquid and the radical polymerizable compound falls in the range of 0.15 or more and 0.55 or less.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] This invention relates to an ion gel, a method for producing the same, a coating material, a negative electrode, and a metal secondary battery using the same. [Background technology]

[0002] Ionic gels, which consist of ionic liquids and polymer networks, are being actively researched as soft materials possessing excellent properties such as non-flammability, non-volatility, and high ionic conductivity derived from ionic liquids.

[0003] Recently, an ionic gel containing 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide ([C2mlm][TFSI]), an aprotic ionic liquid, and poly(ethyl methacrylate) (PMMA), an ultra-high molecular weight polymer, has been developed (see, for example, Non-Patent Literature 1). According to Non-Patent Literature 1, the ionic gel has excellent strength and self-healing properties, and its potential for application in wearable and flexible electrochemical devices has been reported. Although Non-Patent Literature 1 suggests application to electrochemical devices, it has not yet been put into practical use.

[0004] Meanwhile, research into secondary batteries exhibiting high output and high energy density is thriving. In metal batteries using metal as the negative electrode, defects on the surface act as nuclei, causing abnormal metal growth, typified by dendritic growth called dendrites, to precipitate during battery charging (metal electrodeposition). This can lead to short circuits with the positive electrode and problems such as battery ignition. To address these problems, there is a technology to protect the negative electrode with a polymer (see, for example, Patent Document 1). Patent Document 1 discloses forming a protective layer of poly(arylene ethersulfone)-poly(ethylene glycol) graft copolymer (PAES-g-PEG) on the surface of lithium metal. If an alternative protective layer is developed, it would be preferable as it would be compatible with various metal batteries. [Prior art documents] [Patent Documents]

[0005]

Patent Document 1

Non-Patent Document

[0006]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] From the above, an object of the present invention is to provide an ionic gel excellent in strength and ionic conductivity, a method for producing the same, a coating material, a negative electrode, and a metal secondary battery using the same.

Means for Solving the Problems

[0008] The ionic gel according to the present invention is obtained by polymerizing a composition containing a radically polymerizable compound and an ionic liquid. The radically polymerizable compound contains at least a hydrogen-bonding monomer, the ionic liquid contains at least a solvated ionic liquid, the hydrogen-bonding monomer is contained in the radically polymerizable compound at a molar fraction of 15% or more, and the ratio of the mass of the radically polymerizable compound to the total mass of the ionic liquid and the radically polymerizable compound satisfies the range of 0.15 or more and 0.55 or less, thereby solving the above problems. The hydrogen-bonding monomer may be at least one selected from the group consisting of a carboxy group-containing monomer, an amide group-containing monomer, a hydroxy group-containing monomer, a urea bond-containing monomer, and a urethane bond-containing monomer. The hydrogen-bonding monomer may be (meth)acrylic acid and / or N-methyl(meth)acrylamide. The radical polymerizable compound may further contain monomers selected from the group consisting of (meth)acrylic acid esters, (meth)acrylonitrile, vinyl esters, and styrene derivatives. The hydrogen-bonding monomer may be contained in the radical polymerizable compound in such a mole fraction that it satisfies a range of 15% to 70%. The ratio of the mass of the radical polymerizable compound to the total mass of the ionic liquid and the radical polymerizable compound may satisfy the range of 0.15 to 0.50. The solvated ionic liquid may be a complex of a salt containing an alkali metal and / or an alkaline earth metal with a glyme compound and / or a crown ether. The alkali metal and / or alkaline earth metal-containing salt may be a sulfonylimide salt containing a halogen atom. The sulfonylimide salt may be selected from the group consisting of bis(trifluoromethanesulfonyl)imide anion (TFSI), bis(pentafluoroethanesulfonyl)imide anion (BETI), bis(fluorosulfonyl)imide anion (FSI), fluorosulfonyltrifluoromethanesulfonylimide anion (FTA), 4,4,5,5-tetrafluoro-1,3,2-dithiazoline-1,1,3,3-tetraoxide anion (CTFSI), and 2,2,2-trifluoro-N-(trifluoromethylsulfonyl)acetamide anion (TSAC). The alkali metal may be selected from the group consisting of lithium (Li), sodium (Na), and potassium (K), and the alkaline earth metal may be selected from the group consisting of magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba). The glyme compound is selected from the group consisting of diglyme, triglyme, tetraglyme, pentaglyme, and hexaglyme, and the crown ether may be selected from the group consisting of 12-crown-4, 15-crown-5, 18-crown-6, benzo-12-crown-4, benzo-15-crown-5, and benzo-18-crown-6. The ion gel of the present invention has a capacity of 500 kJ / m³. 3 The above mechanical toughness, and 1.0 × 10 -4 It may have an ionic conductivity of S / m or higher. The present invention provides a method for producing the above-mentioned ion gel, comprising preparing a composition containing a radical polymerizable compound, an ionic liquid, and a radical polymerization initiator, and polymerizing the composition, wherein the radical polymerizable compound contains at least a hydrogen-bonding monomer, the ionic liquid contains at least a solvated ionic liquid, the hydrogen-bonding monomer is contained in the radical polymerizable compound in a mole fraction of 15% or more, and the ratio of the mass of the radical polymerizable compound to the total mass of the ionic liquid and the radical polymerizable compound satisfies the range of 0.15 to 0.55, thereby solving the above-mentioned problems. The coating material according to the present invention contains the above-mentioned ionic gel and solvent, thereby solving the above-mentioned problems. The solvent may be selected from the group consisting of water, acids, alcohol-based solvents, alkyl sulfoxide-based solvents, alkylamide-based solvents, pyrrolidone-based solvents, ether-based solvents, ketone-based solvents, and mixtures thereof. The negative electrode according to the present invention comprises a negative electrode active material layer and a protective layer located on the negative electrode active material layer, wherein the protective layer contains the ion gel, thereby solving the above problem. The negative electrode active material layer may be located on the negative electrode current collector. The negative electrode active material layer contains an alkali metal or an alkaline earth metal, and the solvated ionic liquid in the ion gel may contain the same alkali metal or alkaline earth metal as the alkali metal or alkaline earth metal. The protective layer may have a thickness in the range of 0.01 μm to 10 μm. The metal secondary battery according to the present invention comprises a positive electrode, a negative electrode, and an electrolyte, wherein the negative electrode is the negative electrode described above, thereby solving the above problem. [Effects of the Invention]

[0009] The ionic gel of the present invention is obtained by polymerizing a composition containing a radical polymerizable compound containing at least a hydrogen-bonding monomer and an ionic liquid containing at least a solvated ionic liquid. In particular, since the composition contains 15% or more of the hydrogen-bonding monomer by mole fraction and the weight ratio of the radical polymerizable compound is in the range of 0.15 to 0.55, hydrogen bonds are formed between the polymerized polymers, providing a high-strength gel. Furthermore, the solvated ionic liquid provides excellent ionic conductivity. By using such an ionic gel together with a solvent, it functions as a coating material. Using this coating material, a negative electrode coated with a protective film containing the ionic gel can be provided. By employing this negative electrode in a secondary battery, volume changes of the negative electrode due to dendrite generation during charging and discharging can be suppressed, and a secondary battery with improved cycle characteristics can be provided. [Brief explanation of the drawing]

[0010] [Figure 1] Flowchart showing the method for producing the ion gel of the present invention [Figure 2] Schematic diagram showing a negative electrode coated with a protective layer made of the ion gel of the present invention. [Figure 3] Schematic diagram showing the lithium-ion secondary battery of the present invention. [Figure 4] This figure shows the ion gel before and after the tensile test in Example 1. [Figure 5] Figure showing the stress-strain curves of the ionic gel in Example 1 and the ionic gel in Example 17. [Figure 6] Figure showing the Nyquist plot of the ion gel in Example 1. [Figure 7] Figure showing the results of the electrochemical cycle evaluation using a half-cell in Example 18. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described below with reference to the drawings. Similar elements will be given the same numbers, and their descriptions will be omitted. The following description of the constituent elements may be based on typical embodiments of the present invention, but the present invention is not limited to such embodiments.

[0012] Furthermore, in this specification, "(meth)acrylate" refers to both acrylate and methacrylate, or either of them, and "(meth)acrylic" refers to both acrylic and methacrylic, or either of them. Also, "(meth)acryloyl" refers to both acryloyl and methacloyl, or either of them.

[0013] (Embodiment 1) Embodiment 1 details the ion gel of the present invention and a method for producing the same.

[0014] The ionic gel of the present invention is obtained by polymerizing a composition containing a radical polymerizable compound and an ionic liquid. Specifically, the radical polymerizable compound contains at least a hydrogen-bonding monomer, the ionic liquid contains at least a solvated ionic liquid, the hydrogen-bonding monomer is present in the radical polymerizable compound at a mole fraction of 15% or more, and the ratio of the mass of the radical polymerizable compound to the total mass of the ionic liquid and the radical polymerizable compound satisfies the range of 0.15 to 0.55. The inventors of the present invention have found that by satisfying the above-described specific composition, an ionic gel with excellent strength and ionic conductivity can be provided. The components of the composition are described in detail below.

[0015] Radical polymerizable compounds contain at least hydrogen-bonding monomers. This allows for the formation of hydrogen bonds between polymers during in situ polymerization in an ionic liquid, thereby improving the strength of the resulting ionic gel.

[0016] Such hydrogen-bonding monomers are present in the radical polymerizable compound at a mole fraction of 15% or more. This forms the hydrogen bonds necessary to improve the strength of the ionic gel. There is no particular upper limit to the content of hydrogen-bonding monomers; it may be all (100%).

[0017] The hydrogen-bonding monomer is preferably included in the radical polymerizable compound in a mole fraction of 15% to 70%. This range is preferable because the resulting ionic gel has high elongation or strength at break. More preferably, the hydrogen-bonding monomer is included in the radical polymerizable compound in a mole fraction of 20% to 55%. This range is even more preferable because the resulting ionic gel exhibits both high elongation and strength at break, as well as high mechanical toughness.

[0018] Hydrogen-bonding monomers are monomers that have hydrogen-bonding hydrogen atoms in their molecule and are not particularly limited as long as they are radically polymerizable, but preferably at least one is selected from the group consisting of carboxyl group-containing monomers, amide group-containing monomers, hydroxyl group-containing monomers, urea bond-containing monomers, and urethane bond-containing monomers.

[0019] The carboxyl group-containing monomer may be (meth)acrylic acid, monohydroxyethyl acrylic phthalate, p-carboxybenzyl acrylic acid, ethylene oxide-modified (EO addition moles: 2-18) acrylic phthalate, monohydroxypropyl acrylic phthalate, monohydroxyethyl acrylic succinate, β-carboxyethyl acrylate, 2-(4-benzoyl-3-hydroxyphenoxy)ethyl acrylate, maleic acid, monoethyl maleic acid, itaconic acid, citraconic acid, fumaric acid, etc., and one or more of these may be selected and used.

[0020] The amide group-containing monomers may be acrylamide monomers such as (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropylacrylamide, N-methyl(meth)acrylamide, N-butyl(meth)acrylamide, N-hexyl(meth)acrylamide, N-methylol(meth)acrylamide, N-methylol-N-propane(meth)acrylamide, aminomethyl(meth)acrylamide, aminoethyl(meth)acrylamide, mercaptomethyl(meth)acrylamide, mercaptoethyl(meth)acrylamide, etc., N-acryloyl heterocyclic monomers such as N-(meth)acryloylmorpholine, N-(meth)acryloylpiperidine, N-(meth)acryloylpyrrolidine, etc., and N-vinyl group-containing lactam monomers such as N-vinylpyrrolidone, N-vinyl-ε-caprolactam, etc., and one or more of these may be selected and used.

[0021] The hydroxyl group-containing monomer may be hydroxyalkyl esters of (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and 8-hydroxyoctyl (meth)acrylate; glycol mono(meth)acrylates such as polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, and 1,4-cyclohexanedimethanol mono(meth)acrylate; caprolactone-modified (meth)acrylate; hydroxyethylacrylamide; and one or more of these may be selected and used.

[0022] The urea-containing monomer may be a monomer obtained by reacting an amino group-containing monomer with a monofunctional isocyanate compound, or a monomer obtained by reacting an isocyanate group-containing monomer with a monofunctional amine compound, etc.

[0023] The urethane bond-containing monomer may be a monomer obtained by reacting a hydroxyl group-containing monomer with a monofunctional isocyanate compound, or a monomer obtained by reacting an isocyanate group-containing monomer with a monofunctional alcohol compound, etc.

[0024] Among these, (meth)acrylic acid and / or N-methyl(meth)acrylamide are preferred as hydrogen-bonding monomers from the viewpoint of ease of availability and synthesis.

[0025] If the above-mentioned hydrogen-bonding monomer is not present in 100% mole fraction, the radical polymerizable compound contains at least one monomer selected from the group consisting of (meth)acrylic acid esters, (meth)acrylonitrile, vinyl esters, and styrene derivatives. The styrene derivative may be styrene itself or modified with substituents such as methyl groups, as in α-methylstyrene. Polymerization may be promoted by including radical polymerizable compounds other than hydrogen-bonding monomers.

[0026] The ionic liquid contains at least a solvated ionic liquid. In this specification, "solvated ionic liquid" is an equimolar mixture of an organic solvent and a metal salt.

[0027] The organic solvent is not particularly limited as long as it solvates with the metal salt, but preferably, an ether-based solvent can be used. Among ether-based solvents, glyme compounds and / or crown ethers are preferred. These exhibit properties similar to so-called ionic liquids and can form solvated ionic liquids with the metal salt described later.

[0028] Glyme compounds are R 1 -O(CH2CH2O) n -R 2 (R 1 and R 2Each is an alkyl group having 1 to 4 carbon atoms, and they may be the same or different. n is an integer of 2 or more and 6 or less. It is represented by). Among them, diethylene glycol dimethyl ether (diglyme, G2) where n is 2, triethylene glycol dimethyl ether (triglyme, G3) where n is 3, tetraethylene glycol dimethyl ether (tetraglyme, G4) where n is 4, pentaethylene glycol dimethyl ether (pentaglyme, G5) where n is 5, and hexaethylene glycol dimethyl ether (hexaglyme, G6) where n is 6. At least one is selected from the group consisting of. Note that G2 to G6 are all R 1 and R 2 is CH3.

[0029] Crown ether is a macrocyclic ether represented by (-CH2CH2O-) n (n is an integer) and is known as, 12-crown-4, 15-crown-5, 18-crown-6, benzo-12-crown-4, benzo-15-crown-5, benzo-18-crown-6, dibenzo-18-crown-6, dibenzo-24-crown-8, dibenzo-30-crown-10, tribenzo-18-crown-6, asym-dibenzo-22-crown-6, dibenzo-14-crown-4, dicyclohexyl-24-crown-8, cyclohexyl-12-crown-4, 1,2-decaryl-15-crown-5, 1,2-naphtho-15-crown-5, 3,4,5-naphthyl-16-crown-5, 1,2-methylbenzo-18-crown-6, 1,2-tert-butyl-18-crown-6, 1,2-vinylbenzo-15-crown-5, etc. Among them, from the viewpoint of easy availability and ease of handling, at least one is preferably selected from the group consisting of 12-crown-4, 15-crown-5, 18-crown-6, benzo-12-crown-4, benzo-15-crown-5, and benzo-18-crown-6.

[0030] There are no particular restrictions on the type of metal in the metal salt, but the ion gel of the present invention can be used in a battery as long as it contains alkali metals such as lithium (Li), sodium (Na), potassium (K), rubidium (Rb), and cesium (Cs), and / or alkaline earth metals such as beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba). In particular, the alkali metal may be selected from the group consisting of Li, Na, and K, and the alkaline earth metal may be selected from the group consisting of Mg, Ca, Sr, and Ba.

[0031] The salts containing alkali metals and / or alkaline earth metals are preferably sulfonylimide salts containing halogen atoms. The halogen atom is preferably fluorine or bromine, with fluorine being more preferred.

[0032] Sulfonylimide salts containing halogen atoms may be anions containing an imide structure. Examples of such anions include imide anions in which two carbonyl groups are bonded to nitrogen, sulfonylimide anions in which two carbonyl groups are bonded to nitrogen, and sulfonylcarbonylimide anions in which one sulfonyl group and one carbonyl group are bonded to nitrogen. Among these, R 3 -SO2-N - -SO2-R 4 (R 3 and R 4 Each of these is a halogenated alkyl group or halogen atom, which may be the same or different, and R 3 and R 4 It is preferable that the elements be represented as follows (they may be connected to each other to form a ring).

[0033] As specific examples of the above general formula, at least one can be selected from the group consisting of bis(trifluoromethanesulfonyl)imide anion (TFSI), bis(pentafluoroethanesulfonyl)imide anion (BETI), bis(fluorosulfonyl)imide anion (FSI), fluorosulfonyltrifluoromethanesulfonylimide anion (FTA), 4,4,5,5-tetrafluoro-1,3,2-dithiazoline-1,1,3,3-tetraoxide anion (CTFSI), and 2,2,2-trifluoro-N-(trifluoromethylsulfonyl)acetamido anion (TSAC). These are preferred from the viewpoint of solubility in glyme compounds and crown ethers. In particular, when the metal cation is an alkali metal or alkaline earth metal as described above, it is readily available as an ion source for the electrolyte of a battery.

[0034] The solvated ionic liquid is preferably a complex of a salt containing an alkali metal and / or an alkaline earth metal with a glyme compound and / or a crown ether. Any combination of these forms a solvated ionic liquid, which can improve ionic conductivity.

[0035] The ionic liquid may consist solely of a solvated ionic liquid, but it may also contain known ionic liquids that are ionic compounds composed of anions and cations in addition to the solvated ionic liquid. From the viewpoint of ionic conductivity, the content of the solvated ionic liquid in the ionic liquid should be 70% by mass or more.

[0036] The cations in such ionic liquids are Imidazolium cations such as 1,3-dimethylimidazolium, 1,3-diethylimidazolium, 1-ethyl-3-methylimidazolium, 1-methyl-3-butylimidazolium, 1-aryl-3-methylimidazolium, 1-butyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium, 1-butyl-2,3-diethylimidazolium, 3,3'-(butane-1,4-zyl)bis(1-vinyl-3-imidazolium), 1-decyl-3-methylimidazolium, etc. Imidazolinium cations such as 1,2,3,4-tetramethylimidazolinium, 1,3,4-trimethyl-2-ethylimidazolinium, and 1,3-dimethylimidazolinium, Pyridinium cations such as N-butylpyridinium, N-butyl-4-methylpyridinium, N-tert-butyl-4-methylpyridinium, and N-butyl-4-ethylpyridinium, Pyrrolidinium cations such as N,N-butylmethylpyrrolidinium and N,N-butylethylpyrrolidinium, Piperidinium cations such as N,N-ethylmethylpiperidinium and N,N-butylmethylpiperidinium, Ammonium cations such as butyltrimethylammonium, dihexyldimethylammonium, dimethylethylhexylammonium, butyldimethylhexylammonium, cyclohexyltrimethylammonium, ethyldimethylphenylethylammonium, methyltrioctylammonium, etc. The phosphonium cation may be tetrabutylphosphonium, tributyl(2-methoxyethyl)phosphonium, trihexyl(tetradecyl)phosphonium, tributylsulfonium, or other similar phosphonium cations.

[0037] The anions in such ionic liquids include halide ions such as fluoride ions, chloride ions, bromide ions, and iodide ions, as well as nitrate ions, tetrafluoroborate ions, hexafluorophosphate ions, bis(fluorosulfonyl)imide, and AlCl3. - Lactate ions, acetate ions, trifluoroacetate ions, methanesulfonate ions, trifluoromethanesulfonate ions, bis(trifluoromethanesulfonyl)imide ions, bis(pentafluoroethanesulfonyl)imide ions, BF3C2F5 - Tris(trifluoromethanesulfonyl)carbonate ion, perchlorate ion, dicyanamide ion, organic sulfate ion, organic sulfonate ion, R 5 COO - HOOCR 5 COO - NH2CHR 5COO - (At this point, R 5 is a substituent, which is an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, an ether group, an ester group, or an acyl group. The substituent may also contain a fluorine atom.

[0038] In the composition of the present invention, the ionic liquid and the radical polymerizable compound are contained such that the ratio of the mass of the radical polymerizable compound to the total mass of the ionic liquid and the radical polymerizable compound is between 0.15 and 0.55. If the ratio is outside this range, the ionic gel obtained by polymerization will have low viscosity and poor processability, or it will have high viscosity and will not form a gel. Preferably, the ratio of the mass of the radical polymerizable compound to the total mass of the ionic liquid and the radical polymerizable compound is between 0.15 and 0.50. This provides an ionic gel with excellent strength and ionic conductivity. More preferably, the ratio of the mass of the radical polymerizable compound to the total mass of the ionic liquid and the radical polymerizable compound is between 0.15 and 0.45. This provides an ionic gel with even better strength and ionic conductivity.

[0039] Since the ion gel of the present invention is obtained by polymerizing the composition described above, it may contain a radical polymerization initiator used in the polymerization. The amount of radical polymerization initiator contained may be 0.0001% by mass or more and 3% by mass or less based on the total mass of the ion gel.

[0040] The ion gel of the present invention has excellent strength and ionic conductivity, and more specifically, by satisfying the above-mentioned components and composition, it achieves 500 kJ / m³ 3 The above mechanical toughness, and 1.0 × 10 -4 It has an ionic conductivity of S / m or higher. There is no particular upper limit, but the mechanical strength and ionic conductivity of the ionic gel should be 500 kJ / m, respectively. 3 More than 50000kJ / m 3 The following, and 1.0 × 10 -4 S / m or more 1.0×10 -1The ratio may be less than or equal to S / m. In particular, an ionic gel having excellent ionic conductivity may be used as the electrolyte for the secondary battery.

[0041] Next, the method for producing the ion gel of the present invention described above will be explained. Figure 1 is a flowchart showing the method for producing the ion gel of the present invention.

[0042] The ion gel of the present invention is obtained by the following steps S110 and S120. Step S110: Prepare a composition containing a radical polymerizable compound, an ionic liquid, and a radical polymerization initiator. Step S120: Polymerize the composition prepared in Step S110.

[0043] In step S110, the radical polymerizable compound contains at least a hydrogen-bonding monomer, and the ionic liquid contains at least a solvated ionic liquid. Furthermore, the hydrogen-bonding monomer is present in the radical polymerizable compound at a mole fraction of 15% or more, and the ratio of the mass of the radical polymerizable compound to the total mass of the ionic liquid and the radical polymerizable compound is within the range of 0.15 to 0.55. The radical polymerizable compound and the ionic liquid are described above, so their explanation is omitted.

[0044] In step S110, the radical polymerization initiator may be a thermal radical polymerization initiator, a photoradical polymerization initiator, or the like.

[0045] Examples of thermal radical polymerization initiators include peroxides such as t-butyl peroxybenzoate, di-t-butyl peroxide, cumene perhydroxyl, acetyl peroxide, benzoyl peroxide, and lauroyl peroxide, and azo compounds such as azobisisobutyronitrile, azobis-2,4-dimethylvaleronitrile, and azobiscyclohexanecarbonilite.

[0046] Examples of photoradical polymerization initiators include 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methylpropiophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2,2-dimethoxy-1,2-diphenylethane-1-one, 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one, and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide.

[0047] There are no particular restrictions on the content of the radical polymerization initiator, but as an example, when the total content of the radical polymerizable compound and the ionic liquid in the composition is 100 parts by mass, the content is in the range of 0.001 parts by mass to 3 parts by mass. Within this range, polymerization can be carried out without impairing the properties of the resulting ionic gel. One type of radical polymerization initiator may be used, or two or more types may be used, but when two or more types are used, it is preferable that their total content is within the above range.

[0048] The preparation in step S110 only requires mixing the above components of the composition. There are no particular restrictions on the method or order of mixing, but examples include mixing the radical polymerizable compound with the radical polymerization initiator, and then mixing with the ionic liquid.

[0049] The polymerization in step S120 varies depending on the type of radical polymerization initiator. For example, if the composition contains a thermal radical polymerization initiator, heating should be performed in an inert gas atmosphere at a temperature range of 20°C to 130°C for a period of 1 hour to 72 hours. For example, if the composition contains a photoradical polymerization initiator, irradiation should be performed with deep ultraviolet to ultraviolet light (wavelength: 280 nm to 405 nm).

[0050] (Embodiment 2) Embodiment 2 describes the coating material and negative electrode using the ion gel of the present invention as described in Embodiment 1.

[0051] The coating material according to the present invention contains the ion gel described in Embodiment 1 and a solvent. Because the coating material according to the present invention contains the ion gel described above, it can form a protective film that protects the surface of an object with excellent strength. In particular, since the ion gel has ion conductivity, if the coating material according to the present invention is applied to, for example, the negative electrode surface of a secondary battery, the strength of the negative electrode can be increased.

[0052] The solvent is preferably highly compatible with the ionic gel, and may be an example of an aprotic polar solvent. Such a solvent may be at least one selected from the group consisting of water, acids, alcohol-based solvents, alkyl sulfoxide-based solvents, alkylamide-based solvents, pyrrolidone-based solvents, ether-based solvents, ketone-based solvents, and mixtures thereof. These are aprotic polar solvents and have high compatibility with ionic gels.

[0053] Acids include, for example, acetic acid, formic acid, and hydrofluoric acid. Alcohol-based solvents include, for example, methanol, ethanol, propanol, ethylene glycol, glycerin, and propylene glycol monomethyl ether. Alkyl sulfoxide-based solvents include, for example, dimethyl sulfoxide (DMSO), methyl ethyl sulfoxide, and diethyl sulfoxide. Alkylamide-based solvents include, for example, N,N-dimethylformamide (DMF), N,N-diethylformamide, N,N-dimethylacetamide (DMAc), and N,N-diethylacetamide. Pyrrolidone-based solvents include, for example, 2-pyrrolidone, 3-pyrrolidone, and N-methyl-2-pyrrolidone (NMP). Ether-based solvents include diethyl ether and tetrahydrofuran. Ketone-based solvents include acetone, methyl ethyl ketone, and cyclohexanone.

[0054] There are no particular restrictions on the solvent content in the coating material, and it can be set according to the application method. For example, the solvent content can generally be 10% to 90% by mass relative to the total mass of the coating material. The coating material may contain one type of solvent alone, or two or more types. If the coating material contains two or more types of solvents, it is preferable that their total content is within the above numerical range.

[0055] The coating material of the present invention may contain other components as long as it contains the above-mentioned components, provided that it achieves the effects of the present invention. Examples of such components include fillers, pigments, anti-settling agents, defoaming agents, ultraviolet absorbers, antioxidants, surface modifiers, viscosity modifiers, leveling agents, dispersants, and preservatives.

[0056] Furthermore, the method for manufacturing the coating material of the present invention is to mix the ion gel and solvent described in Embodiment 1.

[0057] Next, we will describe the negative electrode whose surface is protected with the coating material of the present invention. Figure 2 is a schematic diagram showing a negative electrode coated with a protective layer made of the ion gel of the present invention.

[0058] The negative electrode 200 is the negative electrode of a secondary battery and comprises a negative electrode active material layer 210 and a protective layer 220 located on the negative electrode active material layer. The protective layer 220 is formed by a coating material according to the present invention and contains the ion gel of the present invention. The ion gel and coating material are as described above and therefore will not be described further.

[0059] The negative electrode active material layer 210 may contain alkali metals such as lithium (Li), sodium (Na), and potassium (K), or alkaline earth metals such as beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba), although this may vary depending on the type of secondary battery.

[0060] The negative electrode active material layer 210 can be an alkali metal element or an alloy thereof, or an alkaline earth metal element or an alloy thereof. In addition, it may also contain metal and metalloid elements of Groups 13 and 14, with elements selected from the group consisting of aluminum, silicon, and tin being preferred. The negative electrode active material layer 210 may be a thin film made of the above metal or alloy.

[0061] The negative electrode active material layer 210 may be located on a negative electrode current collector (not shown). While well-known materials can be used as the negative electrode current collector, examples include metals or alloys such as copper, nickel, titanium, tantalum, and stainless steel, as well as carbon materials such as carbon cloth and carbon paper. Furthermore, if the negative electrode active material layer 210 is a self-supporting film that is advantageous for handling, the negative electrode current collector may be omitted.

[0062] The protective layer 220 contains the ion gel of the present invention as described above. Because the ion gel has excellent strength, it suppresses volume changes caused by dendrites generated during battery charging and discharging, prevents damage to the entire negative electrode 200, and provides a battery with excellent cycle characteristics.

[0063] The type of metal in the solvated ionic liquid contained in the ion gel constituting the protective layer 220 preferably matches the type of metal contained in the negative electrode active material layer 210. That is, if the negative electrode active material layer 210 contains an alkali metal or alkaline earth metal, the solvated ionic liquid contains the same alkali metal or alkaline earth metal. As a result, the excellent ionic conductivity of the ion gel does not impair the battery characteristics.

[0064] The protective layer 220 preferably has a thickness in the range of 0.01 μm to 10 μm. This range is advantageous for maintaining the strength of the negative electrode 200 and for the battery characteristics. The protective layer 220 more preferably has a thickness in the range of 0.1 μm to 1 μm.

[0065] In Figure 2, the protective layer 220 is provided only on one side of the negative electrode active material layer 210, but the protective layer may also be provided on the opposing side.

[0066] There are no particular limitations on the manufacturing method of such a negative electrode 200, but a negative electrode active material layer 210 can be formed on a negative electrode current collector (not shown) by physical vapor deposition, chemical vapor deposition, etc., and the coating material of the present invention can be applied thereon and dried.

[0067] Known methods can be used to apply the coating material. For example, dip coating, spin coating, bar coating, screen printing, brush coating, spray coating, mist coating, flow coating, curtain coating, roll coating, etc.

[0068] The drying process is not particularly limited as long as the solvent in the coating material is removed; it can be air-dried, such as by natural drying, or heated. The above-described method for manufacturing the negative electrode 200 can be applied as a method for forming a protective layer on the surface of an article using the coating material of the present invention, by using a desired article instead of the negative electrode.

[0069] (Embodiment 3) Embodiment 3 describes a secondary battery equipped with a negative electrode using the ion gel of the present invention as described in Embodiment 2.

[0070] Figure 3 is a schematic diagram illustrating the lithium-ion secondary battery of the present invention.

[0071] The secondary battery 300 of the present invention comprises a negative electrode 200, a positive electrode 310, and an electrolyte 320 sandwiched between them. Here, the negative electrode 200 is the negative electrode 200 for the secondary battery of the present invention described with reference to Figure 2, the negative electrode active material layer 210 is a film made of lithium metal or a lithium metal alloy, and the protective layer 220 is an ionic gel containing lithium-containing solvated ions, and redundant explanations are omitted.

[0072] The positive electrode 310 further comprises a current collector 330 and a positive electrode active material layer 340 located thereon. The current collector 330 is not particularly limited as long as it is capable of supplying current, but examples include stainless steel, aluminum (Al), aluminum alloy, titanium, carbon sheet, indium tin oxide (ITO) substrate, tin antimony oxide (ATO) substrate, etc.

[0073] The positive electrode active material layer 340 can use active materials commonly used in lithium-ion secondary batteries. Examples include lithium cobalt oxide (LCO), nickel-cobalt-lithium manganese oxide ternary material (NCM), nickel-cobalt-lithium aluminum oxide ternary material (NCA), lithium manganese oxide (LMO), lithium iron phosphate (LFP), and lithium iron silicate (LFS). Specifically, LiNi(CoAl)O2, LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 O2, LiLiLi 0.5 Mn 0.5 O2, Li2MnO3-LiMO2(M=Co, Ni, Mn), Li 1+x Mn 2-x O4, Li(MnAl)2O4, LiMn 1.5 Ni 0.5 Examples include O4, LiMnPO4, LiFePO4, LiCoPO4, Li2FePO4F, and Li2FeSiO4.

[0074] The positive electrode active material layer 340 may optionally contain a conductive material, a binder, a thickener, and a dispersion medium. The conductive material can be carbon black such as Ketjenblack (registered trademark) or acetylene black, activated carbon, graphite, carbon fiber, carbon nanotubes, carbon nanohorns, or mesoporous carbon. The binder can be polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), or the like.

[0075] The positive electrode 310 is obtained by mixing the positive electrode active material layer 340 with a conductive material, binder, thickener, and dispersion medium as needed, applying the mixture onto the current collector 330, and drying it.

[0076] The electrolyte 320 is not particularly limited as long as it has lithium ion conductivity, but preferably it is an electrolyte solution containing a solvent and a lithium salt that dissolves therein.

[0077] The solvent can be any commonly used lithium-ion conductive solvent. For example, cyclic carbonates such as propylene carbonate (PC) and ethylene carbonate (EC), linear carbonates such as diethyl carbonate (DEC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC), cyclic carboxylic acid esters such as γ-butyrolactone (GBL), γ-valerolactone (GVL), and α-methyl-γ-butyrolactone, linear carboxylic acid esters such as methyl acetate, ethyl acetate, methyl propionate, ethyl butyrate, butyl butyrate, and isobutyl propionate, ethers such as ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, and tetraethylene glycol dimethyl ether, ionic liquids, water, or a mixture of two or more of these solvents can be used.

[0078] Lithium salts commonly used in lithium-ion secondary batteries can be used. For example, lithium hexafluoride phosphate (LiPF6), lithium perchlorate (LiClO4), lithium bistrifluoromethanesulfonylamide (LiTFSA)[(CF3SO2)2NLi], lithium bis(pentafluoroethanesulfonyl)imide (LiBETI), lithium bisfluorosulfonylimide (LiFSI), and lithium halides can be used.

[0079] Although not shown in Figure 3, a separator may be provided between the negative electrode 200 and the positive electrode 310. The separator is a porous membrane, which is a woven or nonwoven fabric, but is exemplified by being made of a resin selected from the group consisting of polyethylene resin, polypropylene resin, polyvinyl alcohol resin, polyethylene terephthalate resin, polyacrylonitrile resin, polyimide resin, and aramid resin, or by being made of glass fiber.

[0080] Figure 3 illustrates a lithium secondary battery, but a lithium-air secondary battery can also be provided by using an air electrode as the positive electrode 310. In this case, the positive electrode active material layer 340 can be a porous carbon material such as carbon black (Ketjenblack®, acetylene black, etc.), activated carbon, graphite, carbon fiber, carbon nanotubes, carbon nanohorns, or mesoporous carbon. Here too, conductive materials, binders, and thickeners may be added along with the porous carbon material. If the porous carbon material is self-supporting, the current collector 330 can be omitted.

[0081] A secondary battery can be provided with a shape such as a coin, cylindrical, prismatic, or sheet by enclosing one or more laminates, as shown in Figure 3, in an outer casing made of a polymer film such as polyethylene or polycarbonate, or a metal film such as aluminum or nickel. Such a secondary battery can be used in various batteries for electronic devices, automobiles, and the like.

[0082] The secondary battery of the present invention is not limited to lithium secondary batteries, but may be modified to be a metal battery of other metals. In this case, it is preferable that the metal contained in the ion gel of the present invention is the same as the metal of the other metal battery.

[0083] The present invention will now be described in detail using specific examples, but please note that the present invention is not limited to these examples. [Examples]

[0084] [Radical polymerizable compounds] The following seven types of radical polymerizable compounds were prepared. • Methyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd., M0087, MMA) • Ethyl methacrylate (manufactured by Tokyo Chemical Industry Co., Ltd., M0084, EMA) • N-methylmethacrylamide (manufactured by Tokyo Chemical Industry Co., Ltd., M0080, MMAm) • N-methylacrylamide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., 241903, MAm) • Methacrylic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., 138-10805, MAAc) • Acrylic acid (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., 011-00776, AAc) • Ethylene glycol dimethacrylate (manufactured by Tokyo Chemical Industry Co., Ltd., E0102, EGDMA) These structural formulas are shown. Of these, N-methylmethacrylamide, N-methylacrylamide, methacrylic acid, and acrylic acid are hydrogen-bonding monomers.

[0085] [ka]

[0086] [Solvatured Ionic Liquids] Three types of solvated ionic liquids were prepared. • [Li(G4)][FSI]; an equimolar mixture of diethylene glycol dimethyl ether (G2) and lithium bis(fluorosulfonyl)imide (LiFSI). • [Li(G4)][TFSI]; an equimolar mixture of tetraethylene glycol dimethyl ether (G4) and lithium bis(fluorosulfonyl)imide (LiFSI). • [Na(G2)][FSI]; an equimolar mixture of diethylene glycol dimethyl ether (G2) and sodium bis(fluorosulfonyl)imide (NaFSI). These structural formulas are shown.

[0087] [ka]

[0088] <[Li(G4)][FSI] synthesis> Lithium bis(fluorosulfonyl)imide (Kishida Chemical Co., Ltd., LBG-45281, LiFSI) and tetraethylene glycol dimethyl ether (Merk, 172405-250G, G4) were weighed into vials in equimolar amounts in a glove box ([O2] < 1 ppm, [H2O] < 10 ppm), stirred overnight at room temperature to obtain the solvated ionic liquid [Li(G4)][FSI].

[0089] <[Li(G4)][TFSI] synthesis> Lithium bis(trifluoromethanesulfonyl)imide (Kishida Chemical Co., Ltd., LBG-43513, LiTFSI) and tetraethylene glycol dimethyl ether (Merk, 172405-250G, G4) were weighed in equimolar amounts into vials in a glove box ([O2] < 1 ppm, [H2O] < 10 ppm), stirred overnight at room temperature, and solvated ionic liquid [Li(G4)][TFSI] was obtained.

[0090] <Synthesis of [Na(G2)][FSI]> Sodium bis(fluorosulfonyl)imide (Kishida Chemical Co., Ltd., MBG-75672, NaFSI) and diethylene glycol dimethyl ether (Merk, 281662-100ML, G2) were weighed into vials in equimolar amounts in a glove box ([O2] < 1 ppm, [H2O] < 10 ppm), stirred overnight at room temperature to obtain the solvated ionic liquid [Na(G2)][FSI].

[0091] [Example 1~ Examples 14, 16, and so on. 17] Example 1~ Examples 14, 16, and so on. Based on Tables 1 to 3, 17 synthesized ionic gels by polymerizing compositions containing various radical polymerizable compounds and solvated ionic liquids.

[0092] The synthesis method for the ionic gel in Example 1 is described below. First, 1.4 g of solvated ionic liquid [Li(G4)][FSI], 0.4 g of methyl methacrylate (MMA), 0.107 g of N-methyl methacrylamide (MMAm), and 0.092 g of methacrylic acid (MAAc), along with 2 μL of 2-hydroxy-2-methylpropiophenone (manufactured by Tokyo Chemical Industry Co., Ltd., H0991) as a radical polymerization initiator, were mixed in a vial to prepare the composition (step S110 in Figure 1). The vial was sealed with a silicone double cap and bubbled with argon using a syringe needle for 15 minutes. The composition thus obtained was polymerized (step S120 in Figure 1). Specifically, the polymerization solution (composition) was injected into a mold in a glove box with a 1 mm silicone spacer sandwiched between polyester films, and photopolymerization was performed by irradiating with 365 nm UV light for 60 minutes using a handy UV light (manufactured by AS ONE). In this way, a sheet-like ionic gel containing a solvated ionic liquid and a hydrogen-bonding polymer was obtained. The synthesis of the hydrogen-bonding polymer was confirmed by gel permeation chromatography and nuclear magnetic resonance analysis, and the polymer concentration was the same as that of the monomer formulation. Example 2~ Examples 14, 16, and so on. The 17 ion gels were synthesized using the same procedure as in Example 1, according to Tables 1 to 3.

[0093] [Table 1]

[0094] [Table 2]

[0095] [Table 3]

[0096] Examples 1~ obtained in this manner Examples 14, 16, and so on.For 17 ionic gels, the mechanical strength was evaluated by tensile testing, and the ionic conductivity was calculated by impedance measurement. (Note: Example 1) 3 Tensile testing was not performed on the ionic gel because it was extremely weak and difficult to mold. Furthermore, the ionic gel in Example 14 was extremely hard, making impedance measurement impossible.

[0097] Sheet-shaped ion gels were punched out using a No. 7 dumbbell-shaped punching die (compliant with JIS K 6251), and tensile tests were performed using a tensile testing machine (Shimadzu Corporation, AGS-X) at a temperature of 25°C and a tensile speed of 10 cm / min. The fracture strength was calculated from the area of ​​the stress-strain curve until the gel fractured. The results are shown in Figures 4 and 5, and Tables 1 to 3.

[0098] A sheet of ion gel was punched out with a 16mm diameter punch, sandwiched between 15.5mm diameter, 0.5mm thick SUS316L spacers, and set in a two-electrode battery evaluation cell (SB2A, EC Frontier). AC impedance measurements were performed at room temperature (25°C) using a Biologic VMP3 potentiostat / galvanostat. The ionic conductivity of the gel was calculated from the resistance value at the intersection of the impedance curve with the real axis in the Nyquist plot. The results are shown in Figure 6 and Tables 1 to 3.

[0099] These results will be summarized and explained below. Figure 4 shows the ionic gel of Example 1 before and after the tensile test. Figure 5 shows the stress-strain curves for the ionic gel of Example 1 and the ionic gel of Example 17.

[0100] Figures 4(A) and 4(B) show the ionic gel of Example 1 before and after the tensile test, respectively. As shown in Figure 4, the ionic gel of Example 1 showed remarkable elongation without fracturing during the tensile test. Although not shown, the ionic gels of Examples 2 to 12 exhibited similar behavior.

[0101] As shown in Figure 5, the fracture elongation and fracture stress of the ionic gel in Example 1 are 1100% and 5 MPa, respectively, and the mechanical toughness calculated from the area of ​​the stress-strain curve is 23,000 kJ / m². 3 These values ​​were extremely high. On the other hand, the fracture elongation and fracture stress of the ionic gel in Example 17 were 50% and 0.15 MPa, respectively, and the mechanical toughness was 48 kJ / m 3 The mechanical toughness of the ionic gels in Examples 2 to 12 was 500 kJ / m² (not shown in the diagram). 3 The above was the result. Mechanical toughness was 500 kJ / m 3 If the above conditions are met, it is effective for protecting materials that require strength.

[0102] Tables 1 to 3 show mechanical toughness of 1000 kJ / m 3 Items exceeding this value are marked with "◎", 500kJ / m³ 3 More than 1000kJ / m 3 "○" indicates values ​​less than 500 kJ / m³. 3 Items less than the specified value were marked with "×". According to Tables 1 to 3, the ionic gels in Examples 1 to 12 have a mechanical toughness of 500 kJ / m². 3 It was found to exceed [a certain value] and exhibit superior mechanical strength.

[0103] Figure 6 shows the Nyquist plot of the ion gel in Example 1.

[0104] The ionic conductivity of the ionic gel in Example 1, calculated from the Nyquist plot in Figure 6, is 4.2 × 10⁻⁶. -3 It was S / m.

[0105] Tables 1 to 3 show ionic conductivity values ​​of 1.0 × 10⁻⁶ calculated from Nyquist plots. -3 Items larger than S / m are marked with "◎", 1.0×10 -4 S / m or more 1.0×10 -3 Items less than S / m are marked with "○", 1.0 × 10 -4 Those with a value less than S / m were marked with "×". According to Table 3, the ion gels in Examples 1 to 12 were 1.0 × 10⁻⁶. -4 It was found to have excellent ionic conductivity of S / m or higher. Ionic conductivity of 1.0 × 10 -4If the conductivity is S / m or higher, it can be applied to applications where conductivity is required.

[0106] These findings indicate that in an ionic gel obtained by polymerizing a composition containing at least a hydrogen-bonding monomer in a radical polymerizable compound and at least a solvated ionic liquid in an ionic liquid, if the hydrogen-bonding monomer is contained in the radical polymerizable compound at a mole fraction of 15% or more, and the ratio of the mass of the radical polymerizable compound to the total mass of the ionic liquid and the radical polymerizable compound is in the range of 0.15 to 0.55, an ionic gel with excellent mechanical strength and ionic conductivity can be obtained.

[0107] [Example 18] In Example 18, a coating material using the ion gel from Example 1 was prepared, and a half-cell was constructed using a metal anode coated with this material, and the battery characteristics were evaluated.

[0108] The ionic gel from Example 1 was dissolved in dimethyl sulfoxide (super-dehydrated) at a weight fraction of 15 wt% in a glove box to prepare a coating material. The resulting solution (coating material) was spin-coated onto a lithium metal anode using a spin coater and vacuum-dried overnight at room temperature. In this way, the surface of the lithium metal anode was coated with a protective layer made of ionic gel. The thickness of the protective layer was 0.3 μm.

[0109] Two lithium metal negative electrodes coated with an ion gel protective layer were punched out with a diameter of 15 mm, and the electrochemical cycle was evaluated in a symmetric coin cell. An equimolar solution of lithium bis(fluorosulfonyl)imide (LiFSI) and G4 was used as the electrolyte. The evaluation conditions were an applied current density of 0.5 mA / cm². 2 The current application time was 1 hour (for both deposition and dissolution). For comparison, an electrochemical cycle evaluation was performed using a lithium metal anode without an ion gel protective layer coating under the same conditions as above. The results are shown in Figure 7.

[0110] Figure 7 shows the results of the electrochemical cycle evaluation using a half-cell in Example 18.

[0111] Figure 7(A) shows the results from a half-cell using a lithium metal anode coated with the ion gel protective layer of Example 1, and Figure 7(B) shows the results from a half-cell using a lithium metal anode not coated with the ion gel protective layer.

[0112] As shown in Figure 7, the cycle characteristics were dramatically improved by using the lithium metal anode coated with the ion gel protective layer of Example 1. Furthermore, when the anode was observed with a scanning electron microscope (SEM) after electrochemical cycle evaluation, some dendrite formation was observed in the anode with the ion gel protective layer, but the volume change was suppressed by the protective layer, and the anode did not break down. On the other hand, dendrites formed in a dendritic manner in the anode without the protective layer and broke down. From this, it was shown that the ion gel of the present invention, which has excellent strength and ion conductivity, is effective as a protective layer for the anode of a battery, and can provide a secondary battery with excellent cycle characteristics. [Industrial applicability]

[0113] The ion gel of the present invention exhibits excellent strength and ion conductivity. By using such an ion gel as a coating material, a negative electrode equipped with a protective film containing the ion gel can be provided. Because such a negative electrode has excellent strength and ion conductivity, it can suppress volume changes of the negative electrode due to dendrite generation during charging and discharging, thereby providing a secondary battery with improved cycle characteristics. [Explanation of Symbols]

[0114] 200 negative electrode 210 Negative electrode active material layer 220 protective layer 300 Secondary battery 310 positive electrode 320 Electrolyte 330 Current collector 340 Cathode active material layer

Claims

1. Ions obtained by polymerizing a composition containing a radical polymerizable compound and an ionic liquid. It is a gel, The radical polymerizable compound contains at least a hydrogen-bonding monomer, The aforementioned ionic liquid consists of a solvated ionic liquid. The hydrogen-bonding monomer is contained in the radical polymerizable compound in a mole fraction of 15% or more. The ratio of the mass of the radical polymerizable compound to the total mass of the ionic liquid and the radical polymerizable compound satisfies the range of 0.15 or more and 0.55 or less. The hydrogen-bonding monomer is (meth)acrylic acid and / or N-methyl(meth)acrylamide. The solvated ionic liquid is an ionic gel, which is a complex of a salt containing an alkali metal and / or an alkaline earth metal with a glyme compound and / or a crown ether.

2. The ionic gel according to claim 1, wherein the radical polymerizable compound further contains a monomer selected from the group consisting of (meth)acrylic acid esters, (meth)acrylonitrile, vinyl esters, and styrene derivatives.

3. The ion gel according to claim 1, wherein the hydrogen-bonding monomer is contained in the radical polymerizable compound in a mole fraction of 15% to 70%.

4. The ionic gel according to claim 1, wherein the ratio of the mass of the radical polymerizable compound to the total mass of the ionic liquid and the radical polymerizable compound satisfies the range of 0.15 to 0.

50.

5. The ion gel according to claim 1, wherein the alkali metal and / or alkaline earth metal-containing salt is a sulfonylimide salt containing a halogen atom.

6. The ionic gel according to claim 5, wherein the sulfonylimide salt is selected from the group consisting of bis(trifluoromethanesulfonyl)imide anion (TFSI), bis(pentafluoroethanesulfonyl)imide anion (BETI), bis(fluorosulfonyl)imide anion (FSI), fluorosulfonyltrifluoromethanesulfonylimide anion (FTA), 4,4,5,5-tetrafluoro-1,3,2-dithiazoline-1,1,3,3-tetraoxide anion (CTFSI), and 2,2,2-trifluoro-N-(trifluoromethylsulfonyl)acetamide anion (TSAC).

7. The alkali metal is selected from the group consisting of lithium (Li), sodium (Na), and potassium (K). The ion gel according to claim 1, wherein the alkaline earth metal is selected from the group consisting of magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba).

8. The aforementioned glyme compound is selected from the group consisting of diglyme, triglyme, tetraglyme, pentaglyme, and hexaglyme. The ion gel according to claim 1, wherein the crown ether is selected from the group consisting of 12-crown-4, 15-crown-5, 18-crown-6, benzo-12-crown-4, benzo-15-crown-5, and benzo-18-crown-6.

9. 500 kJ / m ３ The above mechanical toughness, and 1.0 × 10 －４ The ion gel according to claim 1, having an ionic conductivity of S / m or higher.

10. To prepare a composition containing a radical polymerizable compound, an ionic liquid, and a radical polymerization initiator, Polymerizing the aforementioned composition and It includes, In the above composition, The radical polymerizable compound contains at least a hydrogen-bonding monomer, and the ionic liquid consists of a solvated ionic liquid. The hydrogen-bonding monomer is (meth)acrylic acid and / or N-methyl(meth)acrylamide. The solvated ionic liquid is a complex of a salt containing an alkali metal and / or an alkaline earth metal with a glyme compound and / or a crown ether. The hydrogen-bonding monomer is contained in the radical polymerizable compound in a mole fraction of 15% or more. A method for producing an ionic gel according to any one of claims 1 to 9, wherein the ratio of the mass of the radical polymerizable compound to the total mass of the ionic liquid and the radical polymerizable compound satisfies the range of 0.15 to 0.

55.

11. A coating material containing an ionic gel and a solvent according to any one of claims 1 to 9.

12. The coating material according to claim 11, wherein the solvent is selected from at least one of the group consisting of water, acid, alcohol-based solvent, alkyl sulfoxide-based solvent, alkylamide-based solvent, pyrrolidone-based solvent, ether-based solvent, ketone-based solvent, and mixtures thereof.

13. The negative electrode active material layer, A protective layer located on the negative electrode active material layer and Equipped with, The protective layer contains the ion gel described in any one of claims 1 to 9, wherein the negative electrode.

14. The negative electrode according to claim 13, wherein the negative electrode active material layer is located on the negative electrode current collector.

15. The negative electrode active material layer contains an alkali metal or an alkaline earth metal. The negative electrode according to claim 13, wherein the solvated ionic liquid in the ionic gel contains the same alkali metal or alkaline earth metal as the alkali metal or alkaline earth metal.

16. The negative electrode according to claim 13, wherein the protective layer has a thickness in the range of 0.01 μm to 10 μm.

17. A metal secondary battery comprising a positive electrode, a negative electrode, and an electrolyte, A metal secondary battery wherein the negative electrode is the negative electrode described in claim 13.

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