Polymer electrolyte and secondary battery

Abstract

Disclosed is a polymer electrolyte which has high mechanical strength even at high temperatures, while having high ion conductivity, and with which it is possible to suppress the generation of dendrites at an interface between the polymer electrolyte and a battery negative electrode. The polymer electrolyte contains a polymer which has a specific polyether structure having a free end, a specific crosslinked structure by a polyether, and a specific fluorine sulfonyl imide anion group. The polymer electrolyte contains a specific alkali metal salt in a specific amount, and the volume swelling rate of the polymer electrolyte as determined by a methyl ethyl ketone immersion method is 30% to 120%.

Description

Polymer electrolyte and secondary battery

[0001] The present disclosure relates to a polymer electrolyte and a secondary battery.

[0002] In recent years, the demand for secondary batteries as a power source has expanded with the development of portable devices such as tablet computers and smartphones, as well as electric vehicles. Secondary batteries generally consist of electrodes (positive and negative electrodes) and an electrolyte, and charge and discharge occur through the movement of ions between the electrodes via the electrolyte. These secondary batteries are used in a wide range of applications, from small devices such as mobile phones to large devices such as electric vehicles. Therefore, high safety and further improvements in performance are required.

[0003] To further improve the safety of secondary batteries, development is underway to replace conventional flammable liquid electrolytes with solid electrolytes. Sulfide-, oxide-, and polymer-based solid electrolytes are being widely investigated. To improve the charge / discharge characteristics of secondary batteries, it is generally important to increase the interface between the active material in the electrode and the electrolyte. Here, the active material refers to a substance involved in the reaction that generates electricity. While sulfide- and oxide-based solid electrolytes have excellent ionic conductivity, it is difficult to increase the interface with the active material and they may not have sufficient impact resistance. Therefore, the use of flexible solid electrolytes, such as gel electrolytes that combine liquid electrolytes with polymers, has been proposed.

[0004] Patent Document 1 describes a gel electrolyte containing a polyether and an ionic liquid. Patent Document 2 describes a gel electrolyte in which a quaternary ammonium salt group is incorporated into the main chain to improve affinity with the electrolyte solution. Patent Document 3 describes a dry polymer electrolyte containing glyme and a lithium salt.

[0005] JP 2017-090677 A International Publication No. 2004 / 027789 JP 2009-104891 A

[0006] In recent years, lithium-ion secondary batteries have been required to have not only higher safety but also better charge / discharge characteristics. When polymer gels, as in Patent Documents 1 and 2, are used as electrolytes, their strength decreases at high temperatures, potentially resulting in a short circuit due to impact. Furthermore, dry polymer systems, such as those in Patent Document 3, require the formation of lithium ion complexes with glyme, an organic solvent, to achieve high ionic conductivity. Lithium salts coordinated with glyme are known to form ionic liquids, potentially posing similar challenges to liquid electrolytes. Furthermore, in secondary batteries, dendrites (dendrites) can form at the interface between the electrolyte and the metal negative electrode, potentially shortening the cycle life. Among negative electrode materials for secondary batteries, "metal negative electrodes" have the highest charge capacity density, and their practical application is expected to improve energy density. Since the use of metal negative electrodes is thought to significantly improve the performance of secondary batteries, suppressing dendrite formation is important. Furthermore, dendrite growth can damage the battery's base material and packaging materials, raising safety concerns.

[0007] Therefore, there is a demand for polymer electrolytes that: - Suppress the decrease in impact resistance and the risk of short circuits even at high temperatures; - Have excellent ionic conductivity; and - Have a long cycle life.

[0008] At least one aspect of the present disclosure is directed to a polymer electrolyte that has high mechanical strength and high ionic conductivity even at high temperatures, and that can suppress the formation of dendrites at the interface between the polymer electrolyte and a battery negative electrode. Also, at least one aspect of the present disclosure is directed to providing a secondary battery that has high impact resistance and excellent battery performance even in high-temperature environments.

[0009] According to at least one aspect of the present disclosure, there is provided a polymer electrolyte comprising: a polymer and an alkali metal salt; the alkali metal salt comprises an alkali metal salt having at least one anion selected from the group consisting of bis(trifluoromethanesulfonyl)imide, bis(fluorosulfonyl)imide, and hexafluorophosphate; the polymer has a structure represented by the following formula (1): at least one structure selected from the group consisting of a structure represented by the following formula (2) and a structure represented by the following formula (3): and a structure represented by the following formula (4): wherein A is the total number of moles of anions in the alkali metal salt contained per unit mass of the polymer electrolyte, and B is the number of moles of sulfonylimide groups bonded to the polymer, A and B satisfy the relationship represented by the following formula (X): 0.50≦A / (A+B) (X); and the polymer electrolyte has a volume swelling ratio of 30 to 120% as measured by a methyl ethyl ketone immersion method. (In formula (1), R １ represents a hydrogen atom or a methyl group. ２ represents a linear or branched alkylene group having 1 to 6 carbon atoms. ３ represents an alkyl group having 1 to 6 carbon atoms. ４ R each independently represents a hydrogen atom or a methyl group. ５ and R ６ each independently represents a linear or branched alkylene group having 1 to 6 carbon atoms. ７ R each independently represents a hydrogen atom or a methyl group. ８ , R ９ and R １０ R each independently represents a linear or branched alkylene group having 1 to 6 carbon atoms. １１ represents a trivalent organic group having 1 to 6 carbon atoms. A1, B1, D1, D2 and D3 in formulas (1) to (3) each independently represent at least (—CH ２ CH ２ is a linking group having an ethylene oxide structure represented by the formula: (In formula (4), R １２represents a hydrogen atom or a methyl group. １３ represents a divalent linking group. １４ represents a fluorine atom or a perfluoroalkyl group having 1 to 4 carbon atoms. ＋ represents at least one selected from the group consisting of a lithium ion, a sodium ion, and a potassium ion. The sulfonylimide group represents a functional group represented by the following formula (S): In formula (S), R represents a fluorine atom or a perfluoroalkyl group having 1 to 4 carbon atoms.

[0010] Furthermore, according to at least one embodiment of the present disclosure, there is provided a secondary battery including a positive electrode, a bulk electrolyte, and a negative electrode, wherein at least one of the positive electrode, the bulk electrolyte, and the negative electrode contains the above-described polymer electrolyte.

[0011] According to at least one aspect of the present disclosure, a polymer electrolyte can be obtained that has high mechanical strength and high ionic conductivity even at high temperatures, and that can suppress the formation of dendrites at the interface between the polymer electrolyte and the battery negative electrode. Furthermore, at least one aspect of the present disclosure can provide a secondary battery that has high impact resistance and excellent battery performance even in high-temperature environments.

[0012] Schematic cross-sectional view of a secondary battery using the polymer electrolyte of the present disclosure as a bulk electrolyte. Schematic cross-sectional view of a secondary battery using the polymer electrolyte of the present disclosure as a binder for a positive electrode active material. Schematic cross-sectional view of a secondary battery using the polymer electrolyte of the present disclosure as a binder for a positive electrode active material, a bulk electrolyte, and a binder for a negative electrode active material.

[0013] In the present disclosure, expressions such as "XX or more and YY or less" or "XX to YY" representing a numerical range mean a numerical range including the lower and upper limits, which are the endpoints, unless otherwise specified. Furthermore, when a numerical range is described in stages, the upper and lower limits of each numerical range can be arbitrarily combined. Furthermore, in the present disclosure, expressions such as "at least one selected from the group consisting of XX, YY, and ZZ" mean any of XX, YY, ZZ, a combination of XX and YY, a combination of XX and ZZ, a combination of YY and ZZ, or a combination of XX, YY, and ZZ. Note that when XX is a group, multiple XXs may be selected, and the same applies to YY and ZZ.

[0014] The present inventors have conducted extensive research to obtain a polymer electrolyte that has high mechanical strength even at high temperatures, high ionic conductivity, and suppresses the formation of dendrites at the interface between the polymer electrolyte and the battery negative electrode. First, the present inventors discovered that it is possible to increase ionic conductivity by using a polyether-modified (meth)acrylic resin with a special three-dimensional crosslinking structure in a dry polymer system in which promotion of lithium ion migration by a liquid electrolyte cannot be expected.

[0015] The present inventors have further studied the polyether-modified (meth)acrylic resin, and as a result, have found that an anionic functional group having at least one selected from the group consisting of a fluorinated sulfonylimide (FSI) group and a perfluoroalkylsulfonylimide (PFSI) group is bonded to the molecular chain of the polyether-modified (meth)acrylic resin, and a specific cation X is bonded as a counter ion (cation) of the anionic functional group. ＋ It has been found that by combining the above, a polymer electrolyte can be obtained that can increase the ionic conductivity and the transport number of the specific cation even at low temperatures.

[0016] That is, the polymer electrolyte of the present disclosure satisfies the following conditions: - The three-dimensional crosslinked structure of the polymer has many free terminal chains, one end of which is not bonded to a polymer chain (structure of formula (1)), and has a very low crosslink density (volume swelling ratio); - The three-dimensional crosslinked structure of the polymer has an anionic functional group having a fluorinated sulfonylimide group or a perfluoroalkylsulfonylimide group and a cation (structures of formula (2) and / or (3), and structure of formula (4)). Furthermore, the polymer electrolyte contains a polymer having the anionic functional group in its molecule and an alkali metal salt, which is an electrolyte (supporting electrolyte) that is not fixed to the polymer, in a specific ratio (formula (X)). This makes it possible to suppress the generation of dendrites.

[0017] The inventors speculate that the reason why the polymer electrolyte according to one embodiment of the present disclosure has high ionic conductivity without relying on a liquid electrolyte is as follows: In a dry polymer system, where stabilization of ions such as lithium ions by a liquid electrolyte is not possible, ions move between polymer chains undergoing molecular motion. Therefore, a three-dimensionally crosslinked polymer system, which is used to reduce the risk of short circuits due to membrane deformation at high temperatures, is more susceptible to steric hindrance than a liquid system.

[0018] However, the polymer used in the present disclosure has a three-dimensional crosslinked structure (the structure of formula (2) and / or (3)) and is resistant to deformation even at high temperatures. On the other hand, the polymer has a terminal free chain (the structure of formula (1)) in which one end is not bonded to other polymer chains. This is thought to prevent the polymer from forming a dense network structure, making it less likely to inhibit ion migration while maintaining strength.

[0019] Furthermore, the fluorinated sulfonylimide structure or perfluoroalkylsulfonylimide structure bonded to the polymer makes it difficult to inhibit the movement of ions, and an electrolyte with a high ionic transport number can be provided.

[0020] Furthermore, the fluorinated sulfonylimide structure or perfluoroalkylsulfonylimide structure bonded to the polymer suppresses stereoregularity and reduces the crystallinity of the polymer, which is thought to be why the decrease in ionic conductivity at low temperatures is also suppressed.

[0021] In addition, the anionic group having a fluorinated sulfonylimide structure or a perfluoroalkylsulfonylimide structure and the cation (structure of formula (4)) bonded to the polymer make the polymer highly polar, so that even in a system in which a supporting electrolyte such as a lithium salt is added, the supporting electrolyte is not precipitated and the amount of the supporting electrolyte that can be dissolved can be increased.

[0022] In addition, the use of an alkali metal salt as a supporting electrolyte can suppress localized increases in the concentration of ions, such as lithium ions, near the metal negative electrode. This is thought to be because free anions, which have a higher dissociation rate than immobilized anions, move through the polymer, suppressing interactions between the immobilized anionic groups and ions and leveling out the concentration of ions. In particular, the presence of free anions in a range that satisfies the formula (X): 0.50≦A / (A+B), described below, can suppress ion localization.

[0023] The growth of dendrites is caused by localized concentration of ions, such as lithium ions, in the electrolyte. Therefore, delocalizing the ion distribution suppresses the generation of dendrites and leads to an extension of the cycle life of the secondary battery. The polymer used in this disclosure is designed to have a very low crosslinking density, which allows free anions to move easily. It is believed that the ease of movement of free anions makes the effect of delocalizing the ion distribution more pronounced.

[0024] The three-dimensional crosslinked structure of the polymer has many free chains at one end that are not bonded to a polymer chain, and the extremely low crosslink density is clearly reflected in the volume swelling ratio of the polymer electrolyte measured by the methyl ethyl ketone immersion method. Specifically, the volume swelling ratio of the polymer electrolyte using methyl ethyl ketone (MEK) is 30 to 120%.

[0025] The volume swelling ratio represents the ratio of the volume of a three-dimensional cross-linked polymer before and after it is immersed in a specific solvent and becomes saturated with the solvent. The volume swelling ratio is calculated using the following formula, where the volume of the test specimen is calculated from the weight in air and the weight in water. The specific measurement method will be described later. Volume swelling ratio (%) = (volume when saturated with the solvent due to swelling after immersion) / (volume before immersion in the solvent) x 100

[0026] A volume swelling ratio of less than 30% for a polymer electrolyte is thought to indicate a low number of terminal free chains (the structure of formula (1)) and a high number of three-dimensional crosslinked structures. This results in low ionic conductivity and a low rate characteristic for the secondary battery. Furthermore, the high number of three-dimensional crosslinked structures makes it difficult to achieve the effect of delocalizing ion distribution, resulting in the formation of dendrites. On the other hand, a volume swelling ratio of more than 120% for a polymer electrolyte indicates a lack of three-dimensional crosslinked structures, which can lead to a decrease in strength, such as a decrease in impact resistance at high temperatures. The volume swelling ratio of the polymer electrolyte is preferably 40 to 120%, more preferably 60 to 110%, and even more preferably 70 to 105%.

[0027] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. The components, materials, shapes, relative arrangements, etc. described in these embodiments do not limit the scope of the present disclosure.

[0028] (1) Configuration of Secondary Battery A secondary battery comprises a positive electrode, a bulk electrolyte, and a negative electrode, and at least one of the positive electrode, the bulk electrolyte, and the negative electrode contains the polymer electrolyte of the present disclosure. For example, the bulk electrolyte is a polymer electrolyte. An example of a secondary battery using the polymer electrolyte of the present disclosure is shown in FIGS. 1 to 3. The secondary battery 1 shown in FIG. 1 shows an example of the schematic configuration of a secondary battery using a polymer electrolyte as a bulk electrolyte 7. A positive electrode active material 3 provided on a positive electrode current collector 2 is fixed by a positive electrode active material binder 4 to form a positive electrode 6. The positive electrode 6 may contain a conductive additive 5.

[0029] A negative electrode active material 8 provided on a negative electrode current collector 9 forms a negative electrode 10. In Fig. 1, the negative electrode active material represents metallic lithium, indium, etc. A bulk electrolyte 7 is provided between the positive electrode 6 and the negative electrode 10.

[0030] The secondary battery 1 shown in FIG. 2 shows an example of the schematic configuration of a secondary battery using a polymer electrolyte as a positive electrode active material binder 4. In the embodiment of FIG. 2, a positive electrode 6 contains a polymer electrolyte. For example, the positive electrode 6 has a positive electrode active material 3 and a positive electrode active material binder 4 that fixes the positive electrode active material, and the positive electrode active material binder 4 is the polymer electrolyte of the present disclosure. In the configuration of FIG. 2, a bulk electrolyte 7 represents an oxide-based or sulfide-based inorganic solid electrolyte. The other configurations are the same as those of FIG. 1.

[0031] The secondary battery 1 shown in FIG. 3 illustrates an example of the schematic configuration of a secondary battery using a polymer electrolyte as a positive electrode active material binder 4, a bulk electrolyte 7, and a negative electrode active material binder 11. In the embodiment of FIG. 3, the positive electrode, bulk electrolyte, and negative electrode contain a polymer electrolyte. That is, the positive electrode 6 has a positive electrode active material 3 and a positive electrode active material binder 4 that fixes the positive electrode active material, and the positive electrode active material binder 4 is the polymer electrolyte of the present disclosure. The bulk electrolyte 7 is also the polymer electrolyte of the present disclosure. The negative electrode 10 has a negative electrode active material 8 and a negative electrode active material binder 11 that fixes the negative electrode active material 8, and the negative electrode active material binder 11 is also the polymer electrolyte of the present disclosure. In the configuration of FIG. 3, the negative electrode active material 8 represents a carbon material such as graphite. The other configurations are the same as those of FIG. 1.

[0032] In order to more effectively achieve the effects of the present disclosure, it is preferable that the bulk electrolyte 7 is a polymer electrolyte that penetrates into the positive electrode active material 3 and the negative electrode active material 8, increasing the contact area, as shown in FIGS. 1 and 3 .

[0033] (Method of Manufacturing Solid Secondary Battery) A solid secondary battery can be manufactured by a known cell manufacturing method such as a laminate cell type, a coin cell type, a pressurized cell type, etc. The laminate cell type will be described below as an example.

[0034] A laminate is obtained in which a positive electrode, bulk electrolyte, and negative electrode are disposed between a positive electrode current collector and a negative electrode current collector. Electrode tabs are welded to the positive electrode and negative electrode current collectors. The laminate, in which the positive electrode current collector, positive electrode, bulk electrolyte, negative electrode, and negative electrode current collector are stacked in this order, is wrapped in aluminum laminate film and sealed under reduced pressure using a vacuum packaging machine. The ends of the electrode tabs are exposed to the outside of the laminate film, and the tabs and the aluminum laminate film are sealed in a state where they are bonded by thermocompression. After sealing, if necessary, pressure may be applied using an isostatic pressure device or the like. Examples of bulk electrolytes include solid electrolytes and polymer electrolytes, and both may be used in the laminate. In addition to the above-mentioned laminate, other layers such as elastic materials and resin materials may be stacked within the aluminum laminate film for purposes such as strength and formability. A bipolar type in which multiple laminates are stacked may also be used.

[0035] (Positive electrode current collector) Examples of the positive electrode current collector include metal foil. Examples of metals include aluminum, stainless steel, copper, silver, gold, platinum, nickel, and palladium. The metals may be used alone or in combination of two or more.

[0036] (Positive Electrode Active Material) As the positive electrode active material, for example, a material commonly used in secondary batteries such as lithium ion secondary batteries can be used. For example, (CF) ｍ , (C ２ F) ｍ , MnO ２ , TiS ２ , MoS ２ , FeS ２ , Li ｘＡ CoO ２ , Li ｘＡ NiO ２ , Li ｘＡ MnO ２ , Li ｘＡ Co ｙ Ni １－ｙ O ２ , Li ｘＡ Co ｙ M １－ｙ O ｚ , Li ｘＡ Ni １－ｙ M ｙ O ｚ , Li ｘＢ Mn２ O ４ , Li ｘＢ Mn ２－ｙ M ｙ O ４ (In each of the above formulas, M represents at least one selected from the group consisting of Na, Mg, Sc, Y, Mn, Fe, Co, Ni, Cu, Zn, Al, Cr, Pb, Sb, and B; xA = 0 to 1.2, xB = 0 to 2.0, y = 0 to 0.9, z = 2.0 to 2.3), vanadium oxide and its lithium compound, niobium oxide and its lithium compound, conjugated polymers using organic conductive substances, olivine-based compounds, etc. Note that the xA and xB values ​​in each of the above composition formulas are values ​​before the start of charge and discharge, and increase or decrease with charge and discharge. The positive electrode active material can be used alone or in combination of two or more.

[0037] (Conductive auxiliary material) The conductive auxiliary material can be, for example, a material commonly used in secondary batteries such as lithium-ion secondary batteries. For example, graphites such as natural graphite and artificial graphite, carbon blacks such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black, conductive fibers such as carbon fiber and metal fiber, metal powders such as aluminum powder, conductive whiskers such as zinc oxide whiskers and potassium titanate whiskers, conductive metal oxides such as titanium oxide, and organic conductive materials such as phenylene derivatives. The conductive auxiliary material can be used alone or in combination of two or more.

[0038] (Active Material Binder) As the active material binder, for example, a binder commonly used in secondary batteries such as lithium ion secondary batteries can be used. Examples include polyvinylidene fluoride (PVDF), polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamideimide, polyacrylonitrile, polyacrylic acid, polymethyl acrylate, polyethyl acrylate, polyhexyl acrylate, polymethacrylic acid, polymethyl methacrylate, polyethyl methacrylate, polyhexyl methacrylate, polyvinyl acetate, polyvinylpyrrolidone, polyether, polyethersulfone, hexafluoropolypropylene, styrene-butadiene rubber, and carboxymethyl cellulose.

[0039] The polymer electrolyte of the present disclosure may be used as a bulk electrolyte, a positive electrode active material binder, a negative electrode active material binder, or as a bulk electrolyte, a positive electrode active material binder, and a negative electrode active material binder. That is, it is preferable that the secondary battery satisfy at least one of the following conditions (i) to (iii): (i) A positive electrode 6 has a positive electrode active material 3 and a positive electrode active material binder 4 that fixes the positive electrode active material, and the positive electrode active material binder 4 is the polymer electrolyte of the present disclosure. (ii) A bulk electrolyte 7 is the polymer electrolyte of the present disclosure. (iii) A negative electrode 10 has a negative electrode active material 8 and a negative electrode active material binder 11 that fixes the negative electrode active material 8, and the negative electrode active material binder 11 is the polymer electrolyte of the present disclosure.

[0040] It is particularly preferable to use the polymer electrolyte of the present disclosure as the positive electrode active material binder, since this allows lithium ions to easily reach from the surface to the depths of the positive electrode 6. The active material binder may be used alone or in combination of two or more.

[0041] The positive electrode 6 can be produced, for example, by pressing a positive electrode mixture onto the surface of the positive electrode current collector 2, or by applying a positive electrode mixture slurry, drying it, and then rolling it as necessary to form the positive electrode 6. Alternatively, the positive electrode 6 can be prepared by kneading a positive electrode active material, a conductive additive, and a positive electrode active material binder. The positive electrode mixture slurry can also be prepared, for example, by dissolving or dispersing the positive electrode active material, the conductive additive, and the active material binder in a medium such as dehydrated N-methyl-2-pyrrolidone, acetonitrile, methyl ethyl ketone, or ethylene glycol ethers.

[0042] (Negative electrode current collector) Examples of the negative electrode current collector include metal foil. Examples of metals include aluminum, stainless steel, copper, silver, gold, platinum, nickel, and palladium. The metals may be used alone or in combination of two or more.

[0043] (Negative electrode active material) Examples of the negative electrode active material include metals, metal fibers, carbon materials, oxides, nitrides, silicon, silicon compounds, tin, tin compounds, various alloy materials, etc. Among these, from the viewpoint of capacity density, metals, oxides, carbon materials, silicon, silicon compounds, tin, tin compounds, etc. are preferred.

[0044] Examples of metals include metallic Li and In—Li, and examples of oxides include Li ４ Ti ５ O １２ (LTO: lithium titanate). Examples of carbon materials include various natural graphites, coke, partially graphitized carbon, carbon fiber, spherical carbon, various artificial graphites, and amorphous carbon. Examples of silicon compounds include silicon-containing alloys, silicon-containing inorganic compounds, silicon-containing organic compounds, and solid solutions. Examples of tin compounds include SnO. Ｂ (0<B<2), SnO ２ , SnSiO ３ , Ni ２ Sn ４ , Mg ２ Examples include Sn.

[0045] The negative electrode material may also contain a conductive additive. Examples of the conductive additive include graphite, such as natural graphite and artificial graphite, and carbon black, such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black. When a polymer electrolyte is used as the bulk electrolyte, graphite is particularly suitable as the negative electrode active material.

[0046] Examples of the conductive additive include conductive fibers such as carbon fibers, carbon nanotubes, and metal fibers, metal powders such as carbon fluoride and aluminum, conductive whiskers such as zinc oxide, conductive metal oxides such as titanium oxide, and organic conductive materials such as phenylene dielectrics.

[0047] (Solid Electrolyte) In secondary batteries, a solid electrolyte is disposed between a positive electrode and a negative electrode as a lithium ion migration layer, and may also be used as a bulk electrolyte that functions as a separator. Furthermore, by mixing the solid electrolyte into the active material layers of the positive and negative electrodes, it can also be used as an auxiliary agent that improves the conductivity of lithium ions.

[0048] The polymer electrolyte of the present disclosure can be suitably used as both a bulk electrolyte and an auxiliary material, which allows the contact interface between the bulk electrolyte and the positive and negative electrode active materials to be large, and further has flexibility that allows it to follow the expansion and contraction of the positive and negative electrode active materials, thereby improving the characteristics of the secondary battery.

[0049] Furthermore, by using the polymer electrolyte of the present disclosure as the bulk electrolyte, the effect of suppressing dendrites is easily exhibited, and therefore, it is preferable that the bulk electrolyte is the polymer electrolyte of the present disclosure.

[0050] The bulk electrolyte and auxiliary material may be a solid electrolyte other than a polymer electrolyte. Examples of the solid electrolyte other than a polymer electrolyte include an oxide-based solid electrolyte, a sulfide-based solid electrolyte, and a complex hydride-based solid electrolyte. The oxide-based solid electrolyte is Li １．５ Al ０．５ Ge １．５ (P.O. ４ ) ３ and Li１．３ Al ０．３ Ti １．７ (P.O. ４ ) ３ Nasicon-type compounds such as Li ６．２５ L.A. ３ ZR ２ Al ０．２５ O １２ The oxide-based solid electrolyte may be a garnet-type compound such as Li ０．３３ Li ０．５５ TiO ３ The oxide-based solid electrolyte includes perovskite-type compounds such as Li １４ Zn(GeO ４ ) ４ Lithium-type compounds such as Li ３ P.O. ４ and Li ４ SiO ４ , Li ３ BO ３ Specific examples of sulfide-based solid electrolytes include Li ２ S-SiS ２ , LiI-Li ２ S-SiS ２ , LiI-Li ２ S-P ２ S ５ , LiI-Li ２ S-P ２ O ５ , LiI-Li ３ P.O. ４ -P ２ S ５ , Li ２ S-P ２ S ５ The solid electrolyte may be crystalline or amorphous, or may be glass ceramics. ２ S-P ２ S ５ The description of Li ２ S and P ２ S ５ The term "sulfide-based solid electrolyte" refers to a sulfide-based solid electrolyte formed using raw materials containing the above.

[0051] The polymer electrolyte of the present disclosure can be used as a bulk electrolyte, a binder for a positive electrode active material, or a binder for a negative electrode active material. The configuration of the polymer electrolyte according to one embodiment of the present disclosure will be described in detail below.

[0052] The polymer electrolyte of the present disclosure is preferably a solid electrolyte or semi-solid electrolyte such as a dry polymer electrolyte or a gel electrolyte. That is, a non-liquid electrolyte is preferred. A dry polymer electrolyte is more preferred. The polymer electrolyte preferably does not substantially contain a liquid component, such as a liquid electrolyte.

[0053] <Polymer Electrolyte> A polymer electrolyte according to an embodiment of the present disclosure has a polymer having the following structure. The polymer is, for example, a (meth)acrylic polymer. The polymer electrolyte is, for example, a polyether acrylic resin having a three-dimensional crosslinked structure having the following structure: - A structure represented by formula (1) - At least one structure selected from the group consisting of a structure represented by formula (2) and a structure represented by formula (3) - A structure represented by formula (4)

[0054] The polymer electrolyte has a structure represented by the following formula (1).

[0055] In formula (1), R １ represents a hydrogen atom or a methyl group. ２ represents a linear or branched alkylene group having 1 to 6 carbon atoms (preferably 1 to 4, more preferably 2 to 4). ３ represents an alkyl group having 1 to 6 carbon atoms (preferably 1 to 4, more preferably 1). A1 in formula (1) is a linking group having at least an ethylene oxide structure represented by (—CH2CH2—O—).

[0056] The structure represented by formula (1) is preferably a structure represented by the following formula (1-1). In formula (1-1), R １ represents a hydrogen atom or a methyl group. ２ represents a linear or branched alkylene group having 1 to 6 carbon atoms (preferably 1 to 4, more preferably 2 to 4). ３represents an alkyl group having 1 to 6 carbon atoms (preferably 1 to 4, more preferably 1). m1 and n1 represent the average number of moles added, m1 represents an integer of 1 or more (preferably 1 to 110, more preferably 13 to 46), and n1 represents an integer of 0 or more (preferably 5% to 25% of m1, more preferably 11% to 25% of m1).

[0057] The polymer electrolyte has at least one structure selected from the group consisting of a structure represented by the following formula (2) and a structure represented by the following formula (3). The at least one structure selected from the group consisting of the structure represented by the formula (2) and the structure represented by the formula (3) may be the structure represented by formula (2). This structure can form a three-dimensional crosslinked structure.

[0058] In formula (2), R ４ R each independently represents a hydrogen atom or a methyl group. ５ , R ６ each independently represents a linear or branched alkylene group having 1 to 6 carbon atoms (preferably 1 to 4, more preferably 2 to 4). ７ R each independently represents a hydrogen atom or a methyl group. ８ , R ９ , R １０ R each independently represents a linear or branched alkylene group having 1 to 6 carbon atoms (preferably 1 to 4, more preferably 2 to 4). １１ represents a trivalent organic group having 1 to 6 carbon atoms (preferably 1 to 3, more preferably 1).

[0059] In formulas (2) and (3), B1, D1, D2, and D3 are each independently a linking group having at least an ethylene oxide structure represented by (-CH2CH2-O-). In formulas (1) to (3), it is preferable that A1, B1, D1, D2, and D3 each independently further have a propylene oxide structure represented by (-CH2CH(CH3)-O-). The arrangement of the ethylene oxide structure and the propylene oxide structure may be a block copolymer or a random copolymer. A random copolymer is preferred. Furthermore, A1, B1, D1, D2, and D3 may each independently further contain a diol structure having 1 to 6 carbon atoms (preferably 4 to 6) to the extent that the effects of the present disclosure are not impaired. The diol structure is represented by -O-R ｘ -O-, and R ｘ is an alkylene group having 1 to 6 carbon atoms (preferably 4 to 6).

[0060] The structure represented by formula (2) is preferably a structure represented by the following formula (2-1).

[0061] In formula (2-1), R ４ R each independently represents a hydrogen atom or a methyl group. ５ , R ６ each independently represents a linear or branched alkylene group having 1 to 6 carbon atoms (preferably 1 to 4, more preferably 2 to 4). m2 and n2 represent the average number of moles added, m2 represents an integer of 1 or more (preferably 1 to 110, more preferably 13 to 46), and n2 represents an integer of 0 or more (preferably 5% to 25% of m2, more preferably 11% to 25% of m2).

[0062] The chain sandwiched between the two -COO- may further contain a diol structure having 1 to 6 carbon atoms (preferably 4 to 6 carbon atoms) to the extent that the effect of the present disclosure is not impaired. For example, a diol structure may be contained between ethylene oxide structures, between propylene oxide structures, or between an ethylene oxide structure and a propylene oxide structure. The diol structure is represented by -O-R ｘ -O-, and R ｘ is an alkylene group having 1 to 6 carbon atoms (preferably 4 to 6).

[0063] The structure represented by formula (3) is preferably a structure represented by the following formula (3-1).

[0064] In formula (3-1), R ７ R each independently represents a hydrogen atom or a methyl group. ８ , R ９ , R １０ R each independently represents a linear or branched alkylene group having 1 to 6 carbon atoms (preferably 1 to 4, more preferably 2 to 4). １１ represents a trivalent organic group (preferably a hydrocarbon group) having 1 to 6 carbon atoms (preferably 1 to 3, more preferably 1). m3 and n3 represent the average number of moles added, each m3 independently represents an integer of 1 or more (preferably 1 to 110, more preferably 13 to 46), and each n3 independently represents an integer of 0 or more (preferably 5% to 25% of m3, more preferably 11% to 25% of m3).

[0065] -COO- and R to an extent that does not impair the effects of the present disclosure. １１ The chain sandwiched between these may further contain a diol structure having 1 to 6 carbon atoms (preferably 4 to 6). For example, a diol structure may be contained between ethylene oxide structures, between propylene oxide structures, or between an ethylene oxide structure and a propylene oxide structure. The diol structure is represented by the formula -O-R ｘ -O-, and R ｘ is an alkylene group having 1 to 6 carbon atoms (preferably 4 to 6).

[0066] In the polymer contained in the polymer electrolyte, the average number of moles of ethylene oxide structures added per mole of (meth)acryloyl residue, Meo, is preferably 2.5 moles or more. Meo is more preferably 13 to 46. With Meo in this range, the crosslinking density of the polymer main chain becomes more appropriate, thereby maintaining strength at high temperatures and achieving high lithium ion conductivity. The (meth)acryloyl residue is a form in which a (meth)acryloyl group is addition polymerized, and is represented by the following structure in formula (1), for example:

[0067] Furthermore, in the polymer contained in the polymer electrolyte, the average number of moles of propylene oxide structures added per mole of (meth)acryloyl residue, Mpo, is preferably 5 to 25%, and more preferably 11 to 25%, of the average number of moles of ethylene oxide structures added per mole of (meth)acryloyl residue, Meo. By being in this range, the crystallinity of the polymer main chain is suppressed even if the molecular weight between crosslinking points is large, and inhibition of lithium ion migration, particularly at low temperatures, is more easily suppressed.

[0068] The average number of moles added Meo and Mpo can be measured by decomposing the polymer electrolyte using pyrolysis GC / MS, and quantifying the fragments derived from the (meth)acryloyl residue, the fragments derived from the ethylene oxide structure, and the fragments derived from the propylene oxide structure by creating respective calibration curves. The average number of moles added Mpo is preferably 1 to 15, and more preferably 2 to 10.

[0069] In the polymer electrolyte of the present disclosure, the three-dimensional crosslinked structure of the polymer has a very low crosslink density as described above, and the polymer chains have many free chains at one end that are not bonded to other polymer chains, etc. Such a crosslinked structure can be obtained, for example, by reacting the following materials: polyether mono(meth)acrylate; at least one selected from the group consisting of polyether di(meth)acrylate and polyether tri(meth)acrylate; a compound having an unsaturated reactive functional group and having a cation and an anionic functional group having a fluorinated sulfonylimide group or a perfluoroalkylsulfonylimide group (hereinafter also referred to as a "fluorine sulfonylimide-based ionic compound").

[0070] (Polyether mono(meth)acrylate) Polyether mono(meth)acrylate can form a structure represented by formula (1) (preferably formula (1-1)). As the polyether mono(meth)acrylate, for example, at least one selected from the group consisting of polyethylene glycol mono(meth)acrylate and mono(meth)acrylate of polyethylene glycol-propylene glycol copolymer can be used. When using mono(meth)acrylate of polyethylene glycol-propylene glycol copolymer, the molar ratio of ethylene glycol structure:propylene glycol structure is preferably 100:0 to 50:50, and more preferably 80:20 to 95:5.

[0071] When the molar ratio of the ethylene glycol structure to the propylene glycol structure is within this range, the lithium ion transportability of the polyethylene glycol can be maintained at a high level, and the combination with the structure of formula (4) makes it easier to suppress the inhibition of lithium ion migration due to crystallization of the polymer.

[0072] The polyether mono(meth)acrylate is represented by, for example, the following formula (1'). In formula (1′), R １ , R ２ , R ３ , m1 and n1 are the same as in formula (1-1).

[0073] (Polyether di(meth)acrylate) Polyether di(meth)acrylate can form a structure represented by formula (2) (preferably formula (2-1)). As the polyether di(meth)acrylate, for example, at least one selected from the group consisting of polyethylene glycol di(meth)acrylate and di(meth)acrylate of polyethylene glycol-propylene glycol copolymer can be used. When di(meth)acrylate of polyethylene glycol-propylene glycol copolymer is used, the molar ratio of ethylene glycol structure:propylene glycol structure is preferably 100:0 to 50:50, and more preferably 80:20 to 95:5.

[0074] When the molar ratio of the ethylene glycol structure:propylene glycol structure is within this range, the transportability of ions such as lithium ions by polyethylene glycol can be maintained at a high level, and in combination with the structure of formula (4), it becomes easier to suppress the inhibition of the movement of ions such as lithium ions due to crystallization of the polymer.

[0075] The polyether di(meth)acrylate is represented, for example, by the following formula (2'). In formula (2'), R ４ , R ５ , R ６ , m2 and n2 are the same as in formula (2-1).

[0076] The chain sandwiched between two -COO- may further contain a diol structure having 1 to 6 carbon atoms (preferably 4 to 6 carbon atoms) to the extent that the effects of the present disclosure are not impaired. For example, a diol structure may be contained between ethylene oxide structures, between propylene oxide structures, or between an ethylene oxide structure and a propylene oxide structure. The diol structure is represented by -O-Rx-O-, where Rx is an alkylene group having 1 to 6 carbon atoms (preferably 4 to 6 carbon atoms).

[0077] (Polyether tri(meth)acrylate) Polyether tri(meth)acrylate can form a structure represented by formula (3) (preferably formula (3-1)). As the polyether tri(meth)acrylate, for example, at least one selected from the group consisting of polyethylene glycol tri(meth)acrylate and tri(meth)acrylate of polyethylene glycol-propylene glycol copolymer can be used. When tri(meth)acrylate of polyethylene glycol-propylene glycol copolymer is used, the molar ratio of ethylene glycol structure:propylene glycol structure is preferably 100:0 to 50:50, and more preferably 80:20 to 95:5.

[0078] When the molar ratio of the ethylene glycol structure:propylene glycol structure is within this range, the transportability of ions such as lithium ions by polyethylene glycol can be maintained at a high level, and the combination with the structure of formula (4) makes it easier to suppress the inhibition of the movement of ions such as lithium ions due to crystallization of the polymer.

[0079] The polyether tri(meth)acrylate is represented, for example, by the following formula (3').

[0080] In formula (3'), R ７ , R ８ , R ９ , R １０ , R １１ , m3, and n3 are the same as in formula (3-1). １１ The chain sandwiched between these may further contain a diol structure having 1 to 6 carbon atoms (preferably 4 to 6). For example, a diol structure may be contained between the ethylene oxide structure and the propylene oxide structure. The diol structure is represented by the formula -O-R ｘ -O-, and R ｘ is an alkylene group having 1 to 6 carbon atoms (preferably 4 to 6).

[0081] The structures represented by formula (1), formula (2) and formula (3) (preferably formula (1-1), formula (2-1) and formula (3-1)) can be obtained, for example, by using a polyether polyol obtained by ring-opening polymerization of ethylene oxide and propylene oxide. In formula (1-1), formula (2-1) and formula (3-1) (and formula (1'), formula (2') and formula (3')), (-CH ２ -CH ２ -O-) and an ethylene oxide structure represented by (-CH ２ -CH(CH ３ The arrangement of the propylene oxide structure represented by (III)-(O-) may be a block copolymer or a random copolymer, preferably a random copolymer.

[0082] The mass content of the structure represented by formula (1) in the polymer contained in the polymer electrolyte is defined as α. The total mass content of the structure represented by formula (2) and the structure represented by formula (3) in the polymer (preferably the content of the structure represented by formula (2)) is defined as β. The mass ratio of α to β, α:β, is preferably 70:30 to 98:2, more preferably 88:12 to 96:4, and even more preferably 90:10 to 95:5.

[0083] The mass ratio α:β can be adjusted by specifically adjusting the ratio of polyether mono(meth)acrylate to polyether di(meth)acrylate and / or tri(meth)acrylate. When the mass ratio α:β is within the above range, the polymer does not have an excessively dense network structure, and the strength is maintained while the lithium ion migration is less likely to be hindered, which is particularly preferable.

[0084] In the polymer electrolyte, it is preferable that m1+n1 in formula (1-1) is 1 to 110 (more preferably 14 to 58), and m2+n2 in formula (2-1) and / or m3+n3 in formula (3-1) (preferably m2+n2 and m3+n3) are 1 to 110 (more preferably 14 to 58). By being in the above ranges, the crosslink density of the polymer main chain becomes appropriate, so that the ionic conductivity of the polymer electrolyte is higher while maintaining strength at high temperatures, and the rate characteristics of the secondary battery are also improved.

[0085] In the polymer electrolyte, it is preferable that m1:n1 in formula (1-1) is 80:20 to 95:5 (more preferably 80:20 to 90:10), and m2:n2 in formula (2-1) and / or m3:n3 in formula (3-1) (preferably m2:n2 in formula (2-1) and m3:n3 in formula (3-1)) is 80:20 to 95:5 (more preferably 85:15 to 95:5). By being in the above range, the crystallinity of the polymer main chain is suppressed even if the molecular weight between crosslinking points is large, and it is easier to suppress the inhibition of lithium ion migration, particularly at low temperatures.

[0086] <Fluorine Sulfonylimide Anion Group> The polymer in the polymer electrolyte is characterized by having a structure represented by the following formula (4). In formula (4), R １２ represents a hydrogen atom or a methyl group. １３ represents a divalent linking group. １４ represents a fluorine atom or a perfluoroalkyl group having 1 to 4 carbon atoms (preferably 1 to 2 carbon atoms). ＋ represents a cation, and represents at least one selected from the group consisting of a lithium ion, a sodium ion, and a potassium ion.

[0087] R １３ The divalent linking group in the formula (I) preferably contains a linear or branched alkylene group having 1 to 7 carbon atoms (preferably 2 to 4 carbon atoms). ３０ -(wherein the carbonyl group is R １２ is preferably bonded to the carbon atom to which R is bonded. ３０ is preferably a linear or branched alkylene group having 1 to 7 carbon atoms (preferably 2 to 4 carbon atoms).

[0088] The polyether composition of polyether (meth)acrylates, which are the main components of the polymer, is preferably polyethylene glycol in terms of the transportability of ions such as lithium ions. However, polyethylene glycol has high crystallinity, and in order to suppress crystallization, especially at low temperatures, one method is to copolymerize a propylene glycol structure, which has poor ion transportability, at a certain ratio. As a result, it is difficult to achieve high ionic conductivity using only the polyether composition having the structure of formulas (1) to (3).

[0089] On the other hand, since the structure of formula (4) is an anionic structure with a relatively large molecular size, introducing the structure of formula (4) into the polymer structure can reduce crystallinity. Therefore, even if the propylene glycol structure, which has poor lithium ion transport properties, is reduced in the polyether composition, crystallization at low temperatures can be suppressed. As a result, high ionic conductivity can be maintained even at low temperatures.

[0090] The content of the structure represented by formula (4) in the polymer is preferably 1 to 25 parts by mass, more preferably 1 to 10 parts by mass, and even more preferably 1 to 5 parts by mass, relative to a total of 100 parts by mass of the structures represented by formula (1), formula (2), and formula (3). When the content of formula (4) is within this range, a sufficient amount of ions can be contained while also improving ionic conductivity due to reduced crystallinity. The state after these reactions can be confirmed by analysis using known means, such as combustion ion chromatography, pyrolysis GC / MS, FT-IR, or NMR.

[0091] <Cation> Cation X represented by formula (4) ＋ The cation may be at least one selected from the group consisting of lithium ions, sodium ions, and potassium ions. The cation may be selected depending on the carrier in the secondary battery. For example, lithium is selected for a lithium-ion secondary battery that uses lithium cobalt oxide or the like as the positive electrode active material, and sodium is selected for a sodium-sulfur secondary battery.

[0092] <Supporting Electrolyte> The polymer electrolyte contains an alkali metal salt. The alkali metal salt can serve as a supporting electrolyte. The alkali metal salt includes an alkali metal salt having at least one anion selected from the group consisting of bis(trifluoromethanesulfonyl)imide, bis(fluorosulfonyl)imide, and hexafluorophosphate. The alkali metal salts having the specific anions have a high dissociation rate, and therefore polymer electrolytes using these alkali metal salts can achieve excellent ionic conductivity.

[0093] The alkali metal salt is preferably at least one selected from the group consisting of lithium salts, sodium salts, and potassium salts. For example, in the case of a lithium salt, LiN(CF ３ SO ２ ) ２ , LiN(SO ２ F) ２ , LiPF ６ At least one selected from the group consisting of:

[0094] The total number of moles of anions in the alkali metal salt contained per unit mass of the polymer electrolyte, i.e., bis(trifluoromethanesulfonyl)imide, bis(fluorosulfonyl)imide, and hexafluorophosphate, is designated as A. Furthermore, the number of moles of sulfonylimide groups bonded to the polymer is designated as B. In this case, A and B satisfy the relationship of the following formula (X): 0.50≦A / (A+B) (X) As described above, satisfying formula (X) indicates the presence of many free anions, which can suppress ion localization. If A / (A+B) is less than 0.50, the effect of suppressing ion localization cannot be obtained, and dendrites will occur.

[0095] The sulfonylimide group is represented by the following formula (S).

[0096] In formula (S), R represents a fluorine atom or a perfluoroalkyl group having 1 to 4 carbon atoms (preferably 1 to 2). A and B preferably satisfy the relationship 0.65≦A / (A+B)≦0.96. The content of the alkali metal salt is preferably 5 parts by mass or more and 25 parts by mass or less per 100 parts by mass of the polymer in the polymer electrolyte. When A / (A+B) and the content of the supporting electrolyte are within the above ranges, the alkali metal salt is well miscible with the polymer and does not precipitate, and high ionic conductivity can be obtained without significantly decreasing the ionic transport number, thereby further suppressing the generation of dendrites.

[0097] The polymer electrolyte may contain other supporting electrolytes in addition to the alkali metal salts, to the extent that the effects of the present disclosure are not impaired. For example, other lithium salts include LiBF ４ , LiN(SO ２ C ２ F ５ ) ２ , LiAlCl ４ , LiSBF ６ , LiSCN, LiCF ３ SO ３ , LiAsF ６ , LiClO ４, lower aliphatic lithium carboxylate, LiCl, LiBR, and LiI. The lithium salts may be used alone or in combination of two or more. Examples of the sodium salts and potassium salts include those in which the lithium in the above lithium salts is replaced by sodium or potassium.

[0098] The state of the anions in the polymer electrolyte, that is, A and B, can be confirmed by analysis using known means such as LC / MS, NMR, GPC, and the like.

[0099] <Liquid Electrolyte, Electrolyte Solution> The polymer electrolyte may contain a liquid electrolyte or an electrolytic solution, such as an ionic liquid or a non-aqueous electrolytic solution, as long as the effects of the present disclosure are not impaired and safety at high temperatures is not impaired.

[0100] Specific examples of ionic liquids include the following combinations of cations and anions. The cation may be at least one selected from the group consisting of quaternary ammonium, imidazolium, pyridinium, pyrrolidinium, and piperidinium. The anion may be at least one selected from the group consisting of a fluoroalkylsulfonylimide anion, a fluorosulfonylimide anion, a fluoroalkylsulfonate anion, a fluorosulfonate anion, a fluoroalkylcarboxylate anion, a fluoroalkylmethide anion, a fluoroborate anion, a fluorophosphate anion, a dicyanamide anion, a thiocyanate anion, a bisoxalatoborate anion, a perchlorate anion, and derivatives thereof.

[0101] The non-aqueous electrolyte solution is, for example, a liquid in which about 1 mol of a lithium salt is dissolved in a non-aqueous solvent. Examples of the non-aqueous solvent include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. Examples of the lithium salt include LiPF ６ , LiBF ４ , LiClO ４ Examples include:

[0102] Inclusion of a liquid electrolyte in a polymer electrolyte may improve ionic conductivity, but in order to avoid a decrease in mechanical strength at high temperatures, the amount of liquid electrolyte is preferably, for example, 10 parts by mass or less, 5 parts by mass or less, 1 part by mass or less, or 0.5 parts by mass or less relative to 100 parts by mass of the polymer contained in the polymer electrolyte.

[0103] The polymer electrolyte may contain, as necessary, a non-conductive filler such as silica, quartz powder, titanium oxide, zinc oxide, or calcium carbonate. By adding these non-conductive fillers to the electrolyte layer-forming paint, they function as a film-forming aid when the paint is coated in the electrolyte layer-forming step. The content of such non-conductive fillers is preferably 0.1 parts by mass or more and 10 parts by mass or less relative to 100 parts by mass of the polymer that forms the electrolyte layer.

[0104] Furthermore, the polymer electrolyte may contain a conductive filler, if necessary, to the extent that the effects of the present disclosure are not impaired. Examples of conductive fillers that can be used include conductive fine particles such as carbon black, zinc oxide, tin oxide, and titanium oxide. In particular, when the polymer electrolyte is used as a binder for a positive or negative electrode active material, the internal resistance of the secondary battery can be reduced by including a conductive filler in the polymer electrolyte. The content of the conductive filler is preferably 0.5 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the polymer contained in the polymer electrolyte.

[0105] The polymer electrolyte is preferably a cured product of an electrolyte solution. Examples of the electrolyte solution include a mixture of the following materials: Polyether mono(meth)acrylate At least one compound selected from the group consisting of polyether di(meth)acrylate and polyether tri(meth)acrylate At least one compound selected from the group consisting of compounds having an unsaturated reactive functional group, a fluorinated sulfonylimide group, or a perfluoroalkylsulfonylimide group, and a cation. If necessary, the electrolyte solution may contain a known polymerization initiator. Examples of the polymerization initiator include photopolymerization initiators. Also, known organic solvents such as methyl ethyl ketone may be used.

[0106] (Method for Forming Polymer Electrolyte Layer) The method for forming the polymer electrolyte layer is not particularly limited. For example, the above-mentioned polymer electrolyte materials are mixed by a known method to obtain an electrolyte solution for forming the polymer electrolyte layer. The electrolyte solution is applied by a known application method such as bar coating, spin coating, or roll coating, and then the polymer material contained in the electrolyte solution is polymerized by a known means such as UV to form a polymer electrolyte layer. The polymer electrolyte layer can be formed at a desired position, such as on a positive electrode or a negative electrode. The thickness of the polymer electrolyte layer as a bulk electrolyte is preferably 5.0 μm or more and 100.0 μm or less.

[0107] Specific examples and comparative examples according to the present disclosure are shown below, but the present disclosure is not limited to the following examples and comparative examples.

[0108] First, polyether acrylates forming the structures represented by formula (1) and formula (2) were synthesized. A synthesis example of a polyether monoacrylate capable of forming the structure represented by formula (1) is shown below. <Synthesis of Polyether Monoacrylate> (Polyether Monoacrylate A-1) 15.5 parts by mass of 1-hexanol (manufactured by Tokyo Chemical Industry Co., Ltd.) and 2 parts by mass of potassium hydroxide (manufactured by Kojundo Chemical Laboratory Co., Ltd.) were placed in an autoclave and stirred under reduced pressure at 120°C to dissolve and dehydrate. Next, the pressure inside the system was reduced to -0.1 MPa at 100°C, and 1,041 parts by mass of a gas mixture of ethylene oxide / propylene oxide at a molar fraction of 8:2 was continuously introduced over 260 minutes while maintaining the internal pressure of the vessel at approximately 0.5 MPa. While maintaining the temperature at 100°C, the reaction was carried out for 180 minutes until the internal pressure of the vessel reached 0.2 MPa or less. The temperature was then raised to 130°C over 30 minutes, and stirring was continued until the change in pressure inside the vessel reached 0.01 MPa / 30 minutes. 20 parts by mass of pure water was added to the resulting polymer, and the mixture was stirred at 90°C for 30 minutes. Then, 50 g of an alkali adsorbent, Kyoward 600 (manufactured by Kyowa Chemical Industry Co., Ltd.), was added, and the mixture was stirred for another 30 minutes. The alkali adsorbent was then removed by filtration, and the mixture was dried under reduced pressure at 130°C to obtain a polyether monool having an Mn of 6000.

[0109] Next, 100 parts by mass of the obtained polyether monool, 1.26 parts by mass of acrylic acid (manufactured by Nippon Shokubai Co., Ltd.), 2.02 parts by mass of paratoluenesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.08 parts by mass of hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.), and 250 ml of toluene were charged into a Dean-Stark reactor equipped with a stirrer. The mixture was heated and stirred at 115 ° C., and the reaction was carried out for 5 hours while removing water produced by the reaction from the system. The reaction liquid temperature was then lowered to room temperature, and the mixture was washed twice with 120 g of a 5% aqueous sodium hydroxide solution, and then further washed three times with 120 g of pure water. The organic phase was separated from the reaction liquid after washing, and the solvent was distilled off under reduced pressure to obtain polyether monoacrylate A-1.

[0110] (Polyether Monoacrylate A-2) 18.6 parts by mass of 1-hexanol (Tokyo Chemical Industry Co., Ltd.) and 2 parts by mass of potassium hydroxide (Kojundo Chemical Laboratory Co., Ltd.) were charged into an autoclave and stirred under reduced pressure at 120 ° C. to dissolve and dehydrate. Next, the pressure inside the system was reduced to -0.1 MPa at 100 ° C., and 976 parts by mass of a gas mixture of ethylene oxide / propylene oxide at a molar fraction of 95:5 was continuously introduced over 240 minutes while maintaining the vessel internal pressure at approximately 0.5 MPa. While maintaining the temperature at 100 ° C., the reaction was carried out for 180 minutes until the vessel internal pressure reached 0.2 MPa or less. The temperature was then raised to 130 ° C. over 30 minutes, and stirring was continued until the vessel internal pressure change reached 0.01 MPa / 30 minutes. To the obtained polymer, 20 parts by mass of pure water was added and stirred at 90°C for 30 minutes, and then 50 g of an alkali adsorbent Kyoward 600 (manufactured by Kyowa Chemical Industry Co., Ltd.) was added and stirred for another 30 minutes. Next, the alkali adsorbent was removed by filtration, and the mixture was dried under reduced pressure at 130°C to obtain a polyether monool having an Mn of 5000.

[0111] Next, 100 parts by mass of the obtained polyether monool, 1.51 parts by mass of acrylic acid (manufactured by Nippon Shokubai Co., Ltd.), 2.42 parts by mass of paratoluenesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.08 parts by mass of hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.), and 250 ml of toluene were charged into a Dean-Stark reactor equipped with a stirrer. The mixture was heated and stirred at 115 ° C., and the reaction was carried out for 5 hours while removing water produced by the reaction from the system. The reaction liquid temperature was then lowered to room temperature, and the mixture was washed twice with 120 g of a 5% aqueous sodium hydroxide solution, and then further washed three times with 120 g of pure water. The organic phase was separated from the reaction liquid after washing, and the solvent was distilled off under reduced pressure to obtain polyether monoacrylate A-2.

[0112] (Polyether Monoacrylate A-3) Polyether monoacrylate A-3 was obtained in the same manner as in the preparation of Polyether Monoacrylate A-2, except that the molar fraction of the ethylene oxide / propylene oxide mixed gas was changed to 8:2.

[0113] (Polyether Monoacrylate A-4) 33.7 parts by mass of 1-butanol (manufactured by Tokyo Chemical Industry Co., Ltd.) and 2 parts by mass of potassium hydroxide (manufactured by Kojundo Chemical Laboratory Co., Ltd.) were charged into an autoclave and stirred under reduced pressure at 120 ° C. to dissolve and dehydrate. Next, the pressure inside the system was reduced to -0.1 MPa at 100 ° C., and 984 parts by mass of a gas mixture of ethylene oxide / propylene oxide at a molar fraction of 8:2 was continuously introduced over 240 minutes while maintaining the vessel internal pressure at approximately 0.5 MPa. While maintaining the temperature at 100 ° C., the reaction was carried out for 150 minutes until the vessel internal pressure reached 0.2 MPa or less. The temperature was then raised to 130 ° C. over 30 minutes, and stirring was continued until the vessel internal pressure change reached 0.01 MPa / 30 minutes. To the obtained polymer, 20 parts by mass of pure water was added and stirred at 90°C for 30 minutes, and then 50 g of an alkali adsorbent Kyoward 600 (manufactured by Kyowa Chemical Industry Co., Ltd.) was added and stirred for another 30 minutes. Next, the alkali adsorbent was removed by filtration, and the mixture was dried under reduced pressure at 130°C to obtain a polyether monool having an Mn of 2000.

[0114] Next, 100 parts by mass of the obtained polyether monool, 3.78 parts by mass of acrylic acid (manufactured by Nippon Shokubai Co., Ltd.), 6.05 parts by mass of paratoluenesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.11 parts by mass of hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.), and 250 ml of toluene were charged into a Dean-Stark reactor equipped with a stirrer. The mixture was heated and stirred at 115 ° C., and the reaction was carried out for 6 hours while removing water produced by the reaction from the system. The reaction liquid temperature was then lowered to room temperature, and the mixture was washed twice with 120 g of a 5% aqueous sodium hydroxide solution, and then further washed three times with 120 g of pure water. The organic phase was separated from the reaction liquid after washing, and the solvent was distilled off under reduced pressure to obtain polyether monoacrylate A-4.

[0115] (Polyether Monoacrylate A-5) 67.4 parts by mass of 1-butanol (Tokyo Chemical Industry Co., Ltd.) and 2 parts by mass of potassium hydroxide (Kojundo Chemical Laboratory Co., Ltd.) were charged into an autoclave and stirred under reduced pressure at 120 ° C. to dissolve and dehydrate. Next, the pressure inside the system was reduced to -0.1 MPa at 100 ° C., and 946 parts by mass of a gas mixture of ethylene oxide / propylene oxide at a molar fraction of 8:2 was continuously introduced over 240 minutes while maintaining the vessel internal pressure at approximately 0.5 MPa. While maintaining the temperature at 100 ° C., the reaction was carried out for 130 minutes until the vessel internal pressure reached 0.2 MPa or less. The temperature was then raised to 130 ° C. over 30 minutes, and stirring was continued until the vessel internal pressure change reached 0.01 MPa / 30 minutes. To the obtained polymer, 20 parts by mass of pure water was added and stirred at 90°C for 30 minutes, and then 50 g of an alkali adsorbent Kyoward 600 (manufactured by Kyowa Chemical Industry Co., Ltd.) was added and stirred for another 30 minutes. Next, the alkali adsorbent was removed by filtration, and the mixture was dried under reduced pressure at 130°C to obtain a polyether monool having an Mn of 1000.

[0116] Next, 100 parts by mass of the obtained polyether monool, 7.56 parts by mass of acrylic acid (manufactured by Nippon Shokubai Co., Ltd.), 12.1 parts by mass of paratoluenesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.11 parts by mass of hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.), and 250 ml of toluene were charged into a Dean-Stark reactor equipped with a stirrer. The mixture was heated and stirred at 115 ° C., and the reaction was carried out for 6 hours while removing water produced by the reaction from the system. The reaction liquid temperature was then lowered to room temperature, and the mixture was washed twice with 120 g of a 5% aqueous sodium hydroxide solution, and then further washed three times with 120 g of pure water. The organic phase was separated from the reaction liquid after washing, and the solvent was distilled off under reduced pressure to obtain polyether monoacrylate A-5.

[0117] (Polyether Monoacrylate A-6) 169 parts by mass of 1-butanol (manufactured by Tokyo Chemical Industry Co., Ltd.) and 8 parts by mass of potassium hydroxide (manufactured by Kojundo Chemical Laboratory Co., Ltd.) were charged into an autoclave and stirred under reduced pressure at 120 ° C. to dissolve and dehydrate. Next, the pressure inside the system was reduced to -0.1 MPa at 100 ° C., and 927 parts by mass of a gas mixture of ethylene oxide / propylene oxide at a molar fraction of 8:2 was continuously introduced over 220 minutes while maintaining the vessel internal pressure at approximately 0.5 MPa. While maintaining the temperature at 100 ° C., the reaction was carried out for 120 minutes until the vessel internal pressure reached 0.2 MPa or less. The temperature was then raised to 130 ° C. over 30 minutes, and stirring was continued until the vessel internal pressure change reached 0.01 MPa / 30 minutes. To the obtained polymer, 20 parts by mass of pure water was added and stirred at 90°C for 30 minutes, and then 50 g of an alkali adsorbent Kyoward 600 (manufactured by Kyowa Chemical Industry Co., Ltd.) was added and stirred for another 30 minutes. Next, the alkali adsorbent was removed by filtration, and the mixture was dried under reduced pressure at 130°C to obtain a polyether monool having Mn of 400.

[0118] Next, 100 parts by mass of the obtained polyether monool, 18.9 parts by mass of acrylic acid (manufactured by Nippon Shokubai Co., Ltd.), 24.2 parts by mass of paratoluenesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.11 parts by mass of hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.), and 250 ml of toluene were charged into a Dean-Stark reactor equipped with a stirrer. The mixture was heated and stirred at 115 ° C., and the reaction was carried out for 6 hours while removing water produced by the reaction from the system. The reaction liquid temperature was then lowered to room temperature, and the mixture was washed twice with 120 g of a 5% aqueous sodium hydroxide solution, and then further washed three times with 120 g of pure water. The organic phase was separated from the reaction liquid after washing, and the solvent was distilled off under reduced pressure to obtain polyether monoacrylate A-6.

[0119] (Polyether Monoacrylate A-7) Polyether monoacrylate A-7 was obtained in the same manner as in the preparation of polyether monoacrylate A-5, except that the molar fraction of the ethylene oxide / propylene oxide mixed gas was changed to 5:5.

[0120] (Polyether monomethacrylate A-8) 112 parts by mass of 1-butanol (manufactured by Tokyo Chemical Industry Co., Ltd.) and 5 parts by mass of potassium hydroxide (manufactured by Kojundo Chemical Laboratory Co., Ltd.) were charged into an autoclave and stirred under reduced pressure at 120 ° C. to dissolve and dehydrate. Next, the pressure inside the system was reduced to -0.1 MPa at 100 ° C., and 937 parts by mass of a gas mixture of ethylene oxide / propylene oxide at a molar fraction of 5:5 was continuously introduced over 240 minutes while maintaining the vessel internal pressure at approximately 0.5 MPa. While maintaining the temperature at 100 ° C., the reaction was carried out for 120 minutes until the vessel internal pressure reached 0.2 MPa or less. The temperature was then raised to 130 ° C. over 30 minutes, and stirring was continued until the vessel internal pressure change reached 0.01 MPa / 30 minutes. To the obtained polymer, 20 parts by mass of pure water was added and stirred at 90°C for 30 minutes, and then 50 g of an alkali adsorbent Kyoward 600 (manufactured by Kyowa Chemical Industry Co., Ltd.) was added and stirred for another 30 minutes. Next, the alkali adsorbent was removed by filtration, and the mixture was dried under reduced pressure at 130°C to obtain a polyether monool having Mn of 600.

[0121] Next, 100 parts by mass of the obtained polyether monool, 15.0 parts by mass of methacrylic acid (manufactured by Mitsubishi Gas Chemical Company, Inc.), 20.2 parts by mass of paratoluenesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.11 parts by mass of hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.), and 250 ml of toluene were charged into a Dean-Stark reactor equipped with a stirrer. The mixture was heated and stirred at 115 ° C., and the reaction was carried out for 6 hours while removing water produced by the reaction from the system. The reaction liquid temperature was then lowered to room temperature, and the mixture was washed twice with 120 g of a 5% aqueous sodium hydroxide solution, and then further washed three times with 120 g of pure water. The organic phase was separated from the reaction liquid after washing, and the solvent was distilled off under reduced pressure to obtain polyether monomethacrylate A-8.

[0122] (Polyether Monomethacrylate A-9) A polyether monool having an Mn of 400 was obtained in the same manner as in Polyether Monoacrylate A-6, except that the molar fraction of the ethylene oxide / propylene oxide mixed gas was changed to 5:5.

[0123] Next, 100 parts by mass of the obtained polyether monool, 22.6 parts by mass of methacrylic acid (manufactured by Mitsubishi Gas Chemical Company, Inc.), 24.2 parts by mass of paratoluenesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.11 parts by mass of hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.), and 250 ml of toluene were charged into a Dean-Stark reactor equipped with a stirrer. The mixture was heated and stirred at 115°C, and the reaction was carried out for 6 hours while removing water produced by the reaction from the system. The reaction liquid temperature was then lowered to room temperature, and the mixture was washed twice with 120 g of a 5% aqueous sodium hydroxide solution and then three times with 120 g of pure water. The organic phase was separated from the reaction liquid after washing, and the solvent was distilled off under reduced pressure to obtain polyether monomethacrylate A-9. The obtained polyether mono(meth)acrylates are shown in Table 1.

[0124] Next, a synthesis example of a polyether diacrylate capable of forming the structure represented by formula (2) is shown. <Synthesis of Polyether Diacrylate> (Polyether Diacrylate B-1) 13.7 parts by mass of 1,4-butanediol (manufactured by Tokyo Chemical Industry Co., Ltd.) and 2 parts by mass of potassium hydroxide (manufactured by Kojundo Chemical Laboratory Co., Ltd.) were placed in an autoclave and stirred under reduced pressure at 120°C to dissolve and dehydrate. Next, the pressure inside the system was reduced to -0.1 MPa at 100°C, and 1,041 parts by mass of a gas mixture of ethylene oxide / propylene oxide at a molar fraction of 8:2 was continuously introduced over 280 minutes while maintaining the internal pressure of the vessel at approximately 0.5 MPa. While maintaining the temperature at 100°C, the reaction was carried out for 170 minutes until the internal pressure of the vessel fell to 0.2 MPa or less. The temperature was then raised to 130°C over 30 minutes, and stirring was continued until the change in internal pressure of the vessel reached 0.01 MPa / 30 minutes. To the resulting polymer, 20 parts by mass of pure water was added and stirred at 90°C for 30 minutes, after which 50 g of an alkali adsorbent Kyoward 600 (manufactured by Kyowa Chemical Industry Co., Ltd.) was added and stirred for another 30 minutes. The alkali adsorbent was then removed by filtration, and the resulting mixture was dried under reduced pressure at 130°C to obtain a polyether diol with Mn of 6000.

[0125] Next, 100 parts by mass of the obtained polyether diol, 2.52 parts by mass of acrylic acid (manufactured by Nippon Shokubai Co., Ltd.), 2.02 parts by mass of paratoluenesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.08 parts by mass of hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.), and 250 ml of toluene were charged into a Dean-Stark reactor equipped with a stirrer. The mixture was heated and stirred at 115 ° C., and the reaction was allowed to proceed for 5 hours while removing water produced by the reaction from the system. The reaction liquid temperature was then lowered to room temperature, and the mixture was washed twice with 120 g of a 5% aqueous sodium hydroxide solution, and then three times with 120 g of pure water. The organic phase was separated from the reaction liquid after washing, and the solvent was distilled off under reduced pressure to obtain polyether diacrylate B-1.

[0126] (Polyether Diacrylate B-2) A polyether diol having an Mn of 5000 was obtained in the same manner as in the preparation of Polyether Diacrylate B-1, except that the amount of 1,4-butanediol (manufactured by Tokyo Chemical Industry Co., Ltd.) was changed to 16.4 parts by mass.

[0127] Next, 100 parts by mass of the obtained polyether diol, 3.02 parts by mass of acrylic acid (manufactured by Nippon Shokubai Co., Ltd.), 2.42 parts by mass of paratoluenesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.08 parts by mass of hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.), and 250 ml of toluene were charged into a Dean-Stark reactor equipped with a stirrer. The mixture was heated and stirred at 115 ° C., and the reaction was allowed to proceed for 5 hours while removing water produced by the reaction from the system. The reaction solution temperature was then lowered to room temperature, and the mixture was washed twice with 120 g of a 5% aqueous sodium hydroxide solution, and then three times with 120 g of pure water. The organic phase was separated from the reaction solution after washing, and the solvent was distilled off under reduced pressure to obtain polyether diacrylate B-2.

[0128] (Polyether diacrylate B-3) 41.0 parts by mass of 1,4-butanediol (manufactured by Tokyo Chemical Industry Co., Ltd.) and 2 parts by mass of potassium hydroxide (manufactured by Kojundo Chemical Laboratory Co., Ltd.) were charged into an autoclave and stirred under reduced pressure at 120°C to dissolve and dehydrate. Next, the pressure inside the system was reduced to -0.1 MPa at 100°C, and 955 parts by mass of a gas mixture of ethylene oxide / propylene oxide at a molar fraction of 9:1 was continuously introduced over 220 minutes while maintaining the vessel internal pressure at approximately 0.5 MPa. While maintaining the temperature at 100°C, the reaction was carried out for 150 minutes until the vessel internal pressure reached 0.2 MPa or less. The temperature was then raised to 130°C over 30 minutes, and stirring was continued until the vessel internal pressure change reached 0.01 MPa / 30 minutes. To the resulting polymer, 20 parts by mass of pure water was added and stirred at 90°C for 30 minutes, after which 50 g of an alkali adsorbent Kyoward 600 (manufactured by Kyowa Chemical Industry Co., Ltd.) was added and stirred for another 30 minutes. The alkali adsorbent was then removed by filtration, and the resulting mixture was dried under reduced pressure at 130°C to obtain a polyether diol with Mn of 2000.

[0129] Next, 100 parts by mass of the obtained polyether diol, 7.56 parts by mass of acrylic acid (manufactured by Nippon Shokubai Co., Ltd.), 6.05 parts by mass of paratoluenesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.11 parts by mass of hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.), and 250 ml of toluene were charged into a Dean-Stark reactor equipped with a stirrer. The mixture was heated and stirred at 115 ° C., and the reaction was allowed to proceed for 5 hours while removing water produced by the reaction from the system. The reaction solution temperature was then lowered to room temperature, and the mixture was washed twice with 120 g of a 5% aqueous sodium hydroxide solution, and then three times with 120 g of pure water. The organic phase was separated from the reaction solution after washing, and the solvent was distilled off under reduced pressure to obtain polyether diacrylate B-3.

[0130] (Polyether diacrylate B-4) 205 parts by mass of 1,4-butanediol (Tokyo Chemical Industry Co., Ltd.) and 2 parts by mass of potassium hydroxide (Kojundo Chemical Laboratory Co., Ltd.) were charged into an autoclave and stirred under reduced pressure at 120°C to dissolve and dehydrate. Next, the pressure inside the system was reduced to -0.1 MPa at 100°C, and 899 parts by mass of a gas mixture of ethylene oxide / propylene oxide at a molar fraction of 9:1 was continuously introduced over 210 minutes while maintaining the vessel internal pressure at approximately 0.5 MPa. While maintaining the temperature at 100°C, the reaction was carried out for 110 minutes until the vessel internal pressure reached 0.2 MPa or less. The temperature was then raised to 130°C over 30 minutes, and stirring was continued until the vessel internal pressure change reached 0.01 MPa / 30 minutes. To the resulting polymer, 20 parts by mass of pure water was added and stirred at 90°C for 30 minutes, after which 50 g of an alkali adsorbent Kyoward 600 (manufactured by Kyowa Chemical Industry Co., Ltd.) was added and stirred for another 30 minutes. The alkali adsorbent was then removed by filtration, and the resulting mixture was dried under reduced pressure at 130°C to obtain a polyether diol with Mn of 400.

[0131] Next, 100 parts by mass of the obtained polyether diol, 37.8 parts by mass of acrylic acid (manufactured by Nippon Shokubai Co., Ltd.), 24.2 parts by mass of paratoluenesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.11 parts by mass of hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.), and 250 ml of toluene were charged into a Dean-Stark reactor equipped with a stirrer. The mixture was heated and stirred at 115 ° C., and the reaction was allowed to proceed for 6 hours while removing water produced by the reaction from the system. The reaction solution temperature was then lowered to room temperature, and the mixture was washed twice with 120 g of a 5% aqueous sodium hydroxide solution, and then three times with 120 g of pure water. The organic phase was separated from the reaction solution after washing, and the solvent was distilled off under reduced pressure to obtain polyether diacrylate B-4.

[0132] (Polyether diacrylate B-5) Polyether diacrylate B-5 was obtained in the same manner as in the preparation of polyether diacrylate B-2, except that the molar fraction of the ethylene oxide / propylene oxide mixed gas was changed to 9:1.

[0133] (Polyether Dimethacrylate B-6) A polyether diol with an Mn of 1000 was obtained in the same manner as Polyether Diacrylate B-3, except that the amount of 1,4-butanediol (manufactured by Tokyo Chemical Industry Co., Ltd.) was changed to 82.0 parts by mass and the molar fraction of the ethylene oxide / propylene oxide mixed gas was changed to 5:5. Next, 100 parts by mass of the obtained polyether diol, 18.1 parts by mass of methacrylic acid (manufactured by Mitsubishi Gas Chemical Company, Inc.), 12.1 parts by mass of paratoluenesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.11 parts by mass of hydroquinone (manufactured by Tokyo Chemical Industry Co., Ltd.), and 250 ml of toluene were charged into a Dean-Stark reactor equipped with a stirrer. The mixture was heated and stirred at 115°C, and the reaction was carried out for 6 hours while removing water produced by the reaction from the system. The reaction liquid temperature was then lowered to room temperature, and the mixture was washed twice with 120 g of a 5% aqueous sodium hydroxide solution and then three times with 120 g of pure water. The organic phase was separated from the washed reaction solution, and the solvent was distilled off under reduced pressure to obtain polyether diacrylate B-6.

[0134] The polyether di(meth)acrylates obtained are shown in Table 2. The polyether composition ratios are expressed as mole fractions, where EO represents ethylene oxide and PO represents propylene oxide.

[0135] The polyether composition ratios are expressed as mole fractions, where EO represents ethylene oxide and PO represents propylene oxide.

[0136] <Synthesis of Reactive Ionic Compounds> (Synthesis of Ionic Compound C-1) 15.0 g (0.06 mol) of 3-Sulfopropyl Methacrylate Potassium Salt (manufactured by Tokyo Chemical Industry Co., Ltd.) was suspended in 100 mL of THF and 0.5 mL of N,N-dimethylformamide, and then 20 mL (0.28 mol) of thionyl chloride was added and stirred for 3 hours. This was concentrated under reduced pressure, and the residue was dissolved in dichloromethane. After washing with 50 mL of pure water and 50 mL of brine, the solution was again concentrated under reduced pressure to obtain a pale yellow liquid. The resulting pale yellow liquid was added to a solution of 9.20 g (0.06 mol) of trifluoromethanesulfonamide (manufactured by Tokyo Chemical Industry Co., Ltd.) and 27.3 mL (0.20 mol) of triethylamine (manufactured by Kishida Chemical Co., Ltd.) dissolved in 50 mL of tetrahydrofuran, and the mixture was stirred for 2 hours. The reaction solution was then concentrated under reduced pressure. The resulting residue was dissolved in dichloromethane, washed with 150 mL of pure water, and the organic layer was dried under reduced pressure to obtain a yellow liquid. The resulting yellow liquid was dissolved in 300 mL of tetrahydrofuran, and 1.43 g (0.18 mol) of lithium hydride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added and the mixture was stirred overnight. Unreacted lithium hydride was filtered off using Celite filtration, and the filtrate was dried under reduced pressure to obtain ionic compound C-1.

[0137] (Synthesis of Ionic Compound C-2) Ionic Compound C-2 was obtained in the same manner as for Ionic Compound C-1, except that the starting material was changed to 15.9 g (0.06 mol) of 3-Sulfopropyl Acrylate Potassium Salt (manufactured by Tokyo Chemical Industry Co., Ltd.).

[0138] (Synthesis of Ionic Compound C-3) 7.78 g (0.07 mol) of hydroxymethanesulfonate (manufactured by Atomax Chemical Products Co., Ltd.) was dissolved in 50 mL of THF, and 5.17 g (0.06 mol) of methacrylic acid (manufactured by Kishida Chemical Co., Ltd.) and molecular sieves were added, followed by stirring at 80 ° C. for 3 hours. The filtrate was filtered through Celite and dried under reduced pressure, and then dissolved again in 50 mL of THF, to which 2.41 g (0.06 mol) of potassium hydride (manufactured by Merck & Co., Ltd.) was added, followed by stirring at room temperature for 2 hours. The white solid obtained after drying under reduced pressure was used as the starting material, and ionic compound C-3 was obtained in the same manner as for ionic compound C-1.

[0139] (Synthesis of Ionic Compound C-4) 12.9 g of 1-HEPTANESULFONYL CHLORIDE, 7-HYDROXY (manufactured by Hong Kong Chemhere Products Co., Ltd.) and 6.07 g (0.06 mol) of triethylamine (manufactured by Kishida Chemical Co., Ltd.) were added to 80 mL of dichloromethane and stirred at room temperature. After washing with 100 mL of pure water, the organic phase was dried under reduced pressure to obtain an oily liquid. 5.64 g (0.06 mol) of sodium acrylate (manufactured by Merck) was dissolved in 50 mL of ethanol, and the oily liquid obtained earlier and 0.022 g (0.20 mmol) of hydroquinone (manufactured by Kanto Chemical Co., Ltd.) were added and stirred at 70°C for 5 hours. The pale yellow solid obtained after drying under reduced pressure was used as the starting material to obtain ionic compound C-4 in the same manner as for ionic compound C-2.

[0140] (Synthesis of Ionic Compound C-5) Ionic Compound C-5 was obtained in the same manner as for Ionic Compound C-2, except that the reactant was changed from trifluoromethanesulfonamide (manufactured by Tokyo Chemical Industry Co., Ltd.) to 5.94 g (0.06 mol) of sulfamoylfluoride (manufactured by Atomax Chemicals Products Co., Ltd.).

[0141] (Synthesis of Ionic Compound C-6) Ionic Compound C-6 was obtained in the same manner as for Ionic Compound C-1, except that the reactant was changed from trifluoromethanesulfonamide (manufactured by Tokyo Chemical Industry Co., Ltd.) to 18.0 g (0.06 mol) of nonafluorobutane-1-sulfonamide (manufactured by Enamine Co., Ltd.).

[0142] (Synthesis of Ionic Compound C-7) Ionic Compound C-7 was obtained in the same manner as in the preparation of Ionic Compound C-5, except that lithium hydride was changed to 4.32 g (0.18 mol) of sodium hydride (manufactured by Tokyo Chemical Industry Co., Ltd.) as the reactant.

[0143] (Synthesis of Ionic Compound C-8) Ionic Compound C-8 was obtained in the same manner as for Ionic Compound C-6, except that lithium hydride was changed to 7.22 g (0.18 mol) of potassium hydride (manufactured by Merck) as the reactant.

[0144] The chemical structures of the resulting reactive ionic compounds are shown in formulas C-1 to C-8.

[0145]

[0146] <Preparation of Electrolyte Solution of Polymer Electrolyte> [Example 1] The following materials were mixed and stirred to form a polymer electrolyte: Polyether monoacrylate NK ester M-230G (manufactured by Shin-Nakamura Chemical Co., Ltd.): 50.0 parts by mass Polyether diacrylate B-1: 50.0 parts by mass Ionic compound C-3: 5.0 parts by mass Supporting electrolyte Li.TFSI (lithium bis(trifluoromethanesulfonyl)imide): 20 parts by mass Initiator Omnirad 184 (manufactured by IGM RESINS B.V.): 2.0 parts by mass Next, methyl ethyl ketone (hereinafter referred to as MEK) was added so that the total solids ratio was 60% by mass, and the mixture was then mixed with a motor stirrer to prepare an electrolyte solution.

[0147] (Measurement of volume swelling ratio by MEK immersion method) Test pieces for the volume swelling ratio by the MEK immersion method were prepared as follows using the electrolyte solution of each Example. A predetermined amount of the surface layer-forming dispersion of each Example was added to an aluminum mold with a fluororesin coating on the surface to give a film thickness of 200 μm. Next, the sample was placed on a sunflower stand and dried until the viscosity increased to such an extent that the film surface did not flow, and then placed on a horizontal stand and dried at 60° C. for 2 hours. Next, a high-pressure mercury UV irradiation device (product name: Handy 1000, manufactured by Mario Network Co., Ltd.) was used to irradiate the sample in the air with an accumulated light dose of 5000 mJ / cm. ２The membrane surface was irradiated with UV light so that the polymer electrolyte was crosslinked and cured. After curing, the membrane was left in an environment of 23°C and 40% RH for 24 hours, and the electrolyte membrane was peeled from the aluminum mold to prepare a sheet with a thickness of 200 μm. The obtained polymer electrolyte sheet was cut into a 50 mm x 50 mm piece and left in an environment of 23°C and 40% RH for 24 hours to prepare a test piece.

[0148] First, the initial weight in air (W1) and the initial weight in water (W2) were measured in an environment of 23°C and 40% humidity. Next, the test piece after measuring the initial weight was immersed in MEK at 23°C for 48 hours. Immediately after removing the test piece from MEK, the MEK on the surface was wiped off with a nonwoven fabric, and the test piece was placed in a pre-weighed weighing bottle, and the weight after immersion in air (W3) and the weight after immersion in water (W4) were measured. The volume swelling ratio after immersion in MEK was calculated using the following formula: Volume swelling ratio (%) = ((W3 - W4) - (W1 - W2)) / (W1 - W2) x 100 W1: initial weight in air W2: initial weight in water W3: weight after immersion in air W4: weight after immersion in water

[0149] (Measurement of ionic conductivity at room temperature (25°C)) The electrolyte solution obtained in Example 1 was applied to an aluminum plate having a thickness of 100 µm using a bar coater, and dried at 60°C for 30 minutes. Next, a high-pressure mercury UV irradiation device (product name: Handy 1000, manufactured by Mario Network Co., Ltd.) was used to irradiate the plate with an accumulated light dose of 5000 mJ / cm. ２ The membrane surface was irradiated with UV light so as to crosslink and cure the polymer electrolyte membrane according to Example 1. The membrane thickness after curing was 60 μm.

[0150] The obtained polymer electrolyte membrane was punched together with the aluminum substrate to a diameter of 50 mm and vacuum dried for 48 hours at 80° C. The polymer electrolyte membrane was then placed in an argon-substituted glove box (temperature 25° C., dew point -70° C.), and the AC impedance between the electrodes was measured using an impedance analyzer E4990A (manufactured by KEYSIGHT) at an applied voltage of 10 mV and a frequency range of 100 MHz to 1 Hz. The bulk resistance R was calculated from the real impedance intercept of the obtained cole-cole plot. Ｂ (Ω) was measured, and the ionic conductivity was calculated using the following formula: σ=L / R Ｂ× S (σ: ionic conductivity (S cm －１ ), L: sample thickness (cm), S: sample area (cm ２ ))

[0151] (Measurement of ionic conductivity at low temperature (5°C)) A polymer electrolyte membrane was formed on an aluminum plate in the same manner as in the measurement of ionic conductivity at room temperature. The polymer electrolyte membrane was then placed in an argon-substituted glove box (temperature 25°C, dew point -70°C) and incorporated into an all-solid-state battery evaluation cell (manufactured by Hosen Co., Ltd.). The evaluation cell incorporating the polymer electrolyte membrane was placed in a low-temperature environmental tester and left at 5°C for 1 hour. The ionic conductivity at low temperature was then determined in the same manner as in the above measurement.

[0152] <Preparation of Secondary Battery> 1. Configuration using the polymer electrolyte of the present disclosure as the bulk electrolyte (Preparation of Negative Electrode) A 20 mm x 20 mm, 60 μm thick lithium foil (manufactured by Honjo Metals Co., Ltd.) was laminated on a 20 mm x 30 mm, 20 μm thick copper foil, leaving a 10 mm non-laminated edge on one side, and then pressed to prepare a negative electrode. The total thickness of the prepared negative electrode was 70 μm. A 5 mm wide copper tab with nickel plating on one non-laminated edge was joined to the negative electrode.

[0153] (Preparation of Positive Electrode) 100 parts by mass of lithium cobalt oxide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was mixed with 7 parts by mass of Kureha KF Polymer L#1120 (manufactured by Kureha Corporation) as an active material binder, and 5 parts by mass of Denka Black Li-100 (manufactured by Denka Corporation) as a conductive additive, and 40 parts by mass of N-methylpyrrolidone was added and mixed and stirred. Next, the obtained slurry was coated onto a 15 mm x 25 mm, 20 μm thick rolled aluminum foil, leaving a 10 mm uncoated end on one side, dried at 100 ° C. for 30 minutes, and pressed to obtain a positive electrode. The thickness of the positive electrode was 80 μm. A 5 mm wide aluminum tab was joined to one uncoated end of the positive electrode.

[0154] (Formation of Polymer Electrolyte Layer) An electrolyte solution was applied to the entire active material-coated surface of the obtained positive electrode using a bar coater, and the layer was air-dried at 23° C. for 10 minutes, and then dried at 60° C. for 30 minutes. Next, a high-pressure mercury UV irradiation device (product name: Handy 1000, manufactured by Mario Network) was used to apply a polymer electrolyte layer at an accumulated light dose of 5000 mJ / cm. ２The film surface was irradiated with UV light to cure the film, and the film thickness after curing was 60 μm.

[0155] (Preparation of Secondary Battery Using Polymer Electrolyte as Bulk Electrolyte) The positive electrode coated with the polymer electrolyte was vacuum dried at 80°C for 48 hours. The polymer electrolyte film was then placed in an argon-substituted glove box (temperature 25°C, dew point -70°C), and a polyimide sheet punched into a window frame shape was attached to cover the outer periphery of the positive electrode surface, forming a short-circuit prevention layer. Next, the polymer electrolyte-coated positive electrode polymer electrolyte layer and the negative electrode lithium layer were laminated so as to correspond to each other. The laminate was sandwiched between aluminum laminate films and vacuum-packed to obtain a secondary battery according to Example 1.

[0156] <Battery Characteristic Evaluation> (Rate Characteristics) The theoretical capacity was calculated from the total mass of lithium cobalt oxide contained in the positive electrode. A charge / discharge test was performed at 25°C using a BCS-805 charge / discharge device (Biologic) on the prototype secondary battery. The theoretical capacity was calculated from the total mass of lithium cobalt oxide contained in the positive electrode. The first cycle consisted of a constant current charge at a charge rate of 0.05C and a cutoff value of 3.9V for two hours, followed by a constant current discharge at a discharge rate of 0.05C and a cutoff value of 2.0V for one hour. The charge / discharge cycle was then repeated, with the charge and discharge rates increased by 0.05C each time. The rate at which the charge / discharge could be performed without exceeding the cutoff value was defined as the rate characteristic.

[0157] (Strength Evaluation at High Temperature) The prototype secondary batteries were subjected to impact in an environment of 25°C using a thin film impact tester QC-633 (manufactured by Cometech Testing Machines) with an impact tip diameter of Φ38.1 mm, a load of 120 g, a height of 150 mm, and one repetition, and then a short circuit test of the batteries was performed using a tester. Five batteries were produced for each example, and a total of five impact tests were performed, and the number of batteries that short-circuited was counted. Next, the impact tester and secondary batteries were placed in an environmental tester set to 60°C, and after leaving for two hours, the same test was performed, and the number of batteries that short-circuited in the test at high temperature was counted.

[0158] (Evaluation of short circuit occurrence) The prototype secondary battery was repeatedly charged and discharged in an environment of 40° C. Charging was performed at a charge rate of 0.05 C and a charge voltage of 4.0 V, and discharging was performed at a discharge rate of 0.05 C and a discharge voltage of 3.0 V. The number of cycles until abnormal voltage behavior occurred during charging and discharging was counted.

[0159] Next, the electrodes were removed from the batteries after evaluation, and the electrodes were observed for the presence of dendrites on the surface using a digital microscope VHX-5000 (manufactured by Keyence Corporation) with 50x and 500x objective lenses.

[0160] [Examples 2 to 32] Polymer electrolytes and secondary batteries according to Examples 2 to 32 were prepared in the same manner as in Example 1, except that the types and amounts of polyether mono(meth)acrylate, polyether di(meth)acrylate, ionic compound, and supporting electrolyte were changed as shown in Table 3.

[0161]

[0162] The polymerized structure of the materials used is as follows: M-230G (methoxypolyethylene glycol methacrylate, in formula (1-1) R1: methyl group, R2: ethylene group -(CH ２ ) ２ -, R3: methyl group, m1: 23, n1: 0), AM-130G (methoxypolyethylene glycol #600 acrylate, in formula (1-1) R1: hydrogen atom, R2: ethylene group, R3: methyl group, m1: 13, n1: 0), AM-230G (methoxypolyethylene glycol #1000 acrylate, in formula (1-1) R1: hydrogen atom, R2: ethylene group, R3: methyl group, m1: 23, n1: 0), AM-90G (methoxypolyethylene glycol #400 acrylate, in formula (1-1) R1: hydrogen atom, R2: ethylene group, R3: methyl group, m1: 9, n1: 0), M-450G (methoxypolyethylene glycol methacrylate, in formula (1-1) R1: methyl group, R2: ethylene group, R3: methyl group, m1: 45, n1: 0).

[0163] A-1000PER (R4 in formula (2-1): hydrogen atom, R5: ethylene group or propylene group, R6: ethylene group or propylene group, m2: 17, n2: 4) A-1000 (polyethylene glycol #1000 diacrylate, R4 in formula (2-1): hydrogen atom, R5: ethylene group, R6: ethylene group, m2: 23, n2: 0) A-400 (polyethylene glycol #400 diacrylate, R4 in formula (2-1): hydrogen atom, R5: ethylene group, R6: ethylene group, m2: 9, n2: 0) A-600 (polyethylene glycol #600 diacrylate, R4 in formula (2-1): hydrogen atom, R5: ethylene group, R6: ethylene group, m2: 14, n2: 0)

[0164] A-GLY-20E (ethoxylated glycerin triacrylate, in formula (3-1), R7: hydrogen atom, R8: ethylene group, R9: ethylene group, R10: ethylene group, R11: —CH2(CH—)CH2—, m3: 20 as the total of formula (3-1), n3: 0), 9G: polyethylene glycol #400 dimethacrylate (in formula (2-1), R4: methyl group, R5: ethylene group, R6: ethylene group, m2: 9, n2: 0), 14G: polyethylene glycol #600 dimethacrylate (in formula (2-1), R4: methyl group, R5: ethylene group, R6: ethylene group, m2: 14, n2: 0), all of which are manufactured by Shin-Nakamura Chemical Co., Ltd.

[0165] MEMA-4000: (Polyethylene glycol #4000 dimethacrylate (in formula (2-1), R4: methyl group, R5: ethylene group, R6: ethylene group, m2: 90, n2: 0)) manufactured by Toho Chemical Co., Ltd. PEGDA-4000: (Polyethylene glycol diacrylate, in formula (2-1), R4: hydrogen atom, R5: ethylene group, R6: ethylene group, m2: 90, n2: 0) manufactured by Techno Chemical Co., Ltd.

[0166] Li.TFSI indicates (lithium bis(trifluoromethanesulfonyl)imide). Li.FSI indicates (lithium bis(fluorosulfonyl)imide). Li.PF6 indicates (lithium hexafluorophosphate).

[0167] 2. Configuration using the polymer electrolyte of the present disclosure as a positive electrode active material binder [Example 33] (Preparation of negative electrode) A 20 mm x 20 mm, 60 μm thick lithium foil (manufactured by Honjo Metals Co., Ltd.) was laminated on a 20 mm x 30 mm, 20 μm thick copper foil, leaving a 10 mm non-laminated end on one side, and then pressed to prepare a negative electrode. The total thickness of the prepared negative electrode was 70 μm. A 5 mm wide copper tab with nickel plating on one non-laminated end was joined to the negative electrode.

[0168] (Solid Electrolyte) A LICGC (manufactured by Ohara Corporation) sheet measuring 20 mm x 20 mm and having a thickness of 0.18 mm was used.

[0169] (Preparation of Positive Electrode) 100 parts by mass of lithium cobaltate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was mixed with 18 parts by mass of the electrolyte solution (60% solids) of Example 1 as an active material binder and 5 parts by mass of Denka Black Li-100 (manufactured by Denka Co., Ltd.) as a conductive additive, and 40 parts by mass of N-methylpyrrolidone was added and mixed and stirred. Next, the obtained slurry was coated onto a 15 mm x 25 mm, 20 μm thick rolled aluminum foil, leaving a 10 mm uncoated edge on one side, and then dried at 100 ° C. for 30 minutes. Then, using a high-pressure mercury UV irradiation device (trade name: Handy 1000, manufactured by Mario Network Co., Ltd.), the accumulated light amount was 7000 mJ / cm. ２ The film surface was irradiated with UV light to cure the film. After curing, the film was pressed to obtain a positive electrode having a thickness of 80 μm. A 5 mm wide aluminum tab was joined to one uncoated end of the positive electrode.

[0170] (Preparation of Secondary Battery Using Polymer Electrolyte as Positive Electrode Active Material Binder) A positive electrode using a polymer electrolyte as an active material binder was vacuum dried at 80°C for 48 hours. The polymer electrolyte membrane was then placed in an argon-substituted glove box (temperature 25°C, dew point -70°C), and the positive electrode / solid electrolyte / negative electrode were laminated in this order. The laminate was sandwiched between aluminum laminate films and vacuum-packed to obtain a secondary battery using the polymer electrolyte of the present disclosure as a positive electrode active material binder according to Example 33.

[0171] [Examples 34 to 36] Secondary batteries according to Examples 34 to 36 were fabricated in the same manner as in Example 33, except that the electrolyte solution (polymer electrolyte) was changed as shown in Table 7. Evaluation results such as rate characteristics are shown in Table 7.

[0172] 3. Configuration using the polymer electrolyte of the present disclosure as the bulk electrolyte, positive electrode active material binder, and negative electrode active material binder [Example 37] (Preparation of negative electrode) 100 parts by mass of graphite powder (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was mixed with 20 parts by mass of the electrolyte solution (60% solids) of Example 1 as the active material binder and 5 parts by mass of Denka Black Li-100 (manufactured by Denka Co., Ltd.) as the conductive additive, and 80 parts by mass of N-methylpyrrolidone was added and mixed and stirred. Next, the obtained slurry was coated onto a 20 mm x 30 mm, 20 μm thick copper foil, leaving a 10 mm uncoated edge on one side, and then dried at 100 ° C. for 30 minutes. Using a high-pressure mercury UV irradiation device (trade name: Handy 1000, manufactured by Mario Network Co., Ltd.), the cumulative light dose was 8000 mJ / cm ２ The film surface was irradiated with UV light to cure the film. After curing, the film was pressed to obtain a negative electrode having a thickness of 80 μm. Negative electrode active material non-coated portions, on neither side of which the negative electrode active material was coated, were provided at both ends, and a 5 mm wide nickel-plated copper current collecting tab was joined to one of the negative electrode active material non-coated portions.

[0173] (Preparation of Positive Electrode) 100 parts by mass of lithium cobaltate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was mixed with 18 parts by mass of the electrolyte solution (60% solids) of Example 1 as an active material binder and 5 parts by mass of Denka Black Li-100 (manufactured by Denka Co., Ltd.) as a conductive additive, and 40 parts by mass of N-methylpyrrolidone was added and mixed and stirred. Next, the obtained slurry was coated on a rolled aluminum foil with a thickness of 20 μm, dried at 60° C. for 30 minutes, and then irradiated with a high-pressure mercury UV irradiation device (trade name: Handy 1000, manufactured by Mario Network Co., Ltd.) with an integrated light dose of 7000 mJ / cm. ２ The film surface was irradiated with UV light to cure the film. After curing, the film was pressed to obtain a positive electrode having a thickness of 80 μm. Neither of the positive electrode active material-coated portions was provided at either end, and a 5 mm-wide aluminum current collecting tab was joined to one of the positive electrode active material-coated portions.

[0174] (Formation of Polymer Electrolyte Layer) The electrolyte solution of Example 1 was applied to the obtained positive electrode using a bar coater, and the layer was air-dried at 23° C. for 10 minutes, and then dried at 60° C. for 30 minutes. Next, a high-pressure mercury UV irradiation device (product name: Handy 1000, manufactured by Mario Network Co., Ltd.) was used to irradiate the layer with an accumulated light dose of 5000 mJ / cm. ２ The film surface was irradiated with UV light to cure the film, and the film thickness after curing was 60 μm.

[0175] (Preparation of Secondary Battery Using Polymer Electrolyte as Bulk Electrolyte, Positive Electrode Active Material Binder, and Negative Electrode Active Material Binder) The above-mentioned positive electrode and negative electrode coated with the polymer electrolyte were vacuum-dried at 80°C for 48 hours. The polymer electrolyte film was then placed in an argon-substituted glove box (temperature 25°C, dew point -70°C), and a polyimide sheet punched into a window frame shape was attached to cover the outer periphery of the positive electrode surface, forming a short-circuit prevention layer. Next, the polymer electrolyte layer of the positive electrode coated with the polymer electrolyte and the active material layer of the negative electrode were laminated so as to correspond to each other. The laminate was sandwiched between aluminum laminate films and vacuum-packed to obtain a secondary battery using the polymer electrolyte of the present disclosure as the bulk electrolyte, positive electrode active material binder, and negative electrode active material binder according to Example 37.

[0176] [Examples 38 to 40] Secondary batteries according to Examples 38 to 40 were fabricated in the same manner as in Example 37, except that the electrolyte solution (polymer electrolyte) was changed as shown in Table 7. Evaluation results such as rate characteristics are shown in Table 7.

[0177] <Comparative Examples> [Comparative Example 1] The following materials were mixed and stirred to form a polymer electrolyte. Polyether monomethacrylate NK-ester M-40G (manufactured by Shin-Nakamura Chemical Co., Ltd.): 70 parts by mass Polyether dimethacrylate 4G (manufactured by Shin-Nakamura Chemical Co., Ltd.): 30 parts by mass Lithium bis(trifluoromethanesulfonyl)imide (manufactured by Kishida Chemical Co., Ltd.: 10.0 parts by mass Initiator Omnirad 184 (manufactured by IGM RESINS B.V.): 2.0 parts by mass Next, methyl ethyl ketone was added so that the total solids ratio was 60% by mass, and the mixture was mixed with a motor stirrer to prepare an electrolyte solution. Thereafter, a polymer electrolyte and a secondary battery according to Comparative Example 1 were fabricated in the same manner as in Example 1.

[0178] Comparative Examples 2 to 6 Polymer electrolytes and secondary batteries according to Comparative Examples 2 to 6 were prepared in the same manner as in Example 1, except that the types and amounts of polyether mono(meth)acrylate, polyether di(meth)acrylate, ionic compound, and supporting electrolyte were changed as shown in Table 4.

[0179] The secondary batteries of Comparative Examples 1 to 6 were configured to use a polymer electrolyte as the bulk electrolyte. Table 6 shows the evaluation results of rate characteristics and the like.

[0180] The structures of the materials used when polymerized are as follows: M-40G: methoxytetraethylene glycol methacrylate (in formula (1-1), R1 is a methyl group, R2 is an ethylene group, R3 is a methyl group, m1: 3, n1: 0) 4G: polyethylene glycol #200 dimethacrylate (in formula (2-1), R4 is a methyl group, R5 is an ethylene group, R6 is an ethylene group, m2: 4, n2: 0) APG-400: polypropylene glycol #400 diacrylate (in formula (2-1), R4 is a hydrogen atom, R5 is a propylene group, R6 is a propylene group, m2: 0, n2: 7) AM-90G, AM-130G, and A-600 are as described above. All of the above are manufactured by Shin-Nakamura Chemical Co., Ltd. PA-500: Hydroxypolypropylene glycol monoacrylate (in formula (1-1), R1 is a hydrogen atom, R2 is a propylene group, R3 is a hydroxyl group, m1 is 0, n1 is 5), manufactured by Toho Chemical Industry Co., Ltd.

[0181] Comparative Example 7 A secondary battery according to Comparative Example 7 was fabricated in the same manner as in Example 33, except that 7 parts by mass of Kureha KF Polymer L#1120 (manufactured by Kureha Corporation) was used as the positive electrode active material binder.

[0182] [Comparative Examples 8 to 10] Secondary batteries according to Comparative Examples 8 to 10 were fabricated in the same manner as in Example 33, except that the types and amounts of polyether mono(meth)acrylate, polyether di(meth)acrylate, ionic compound, and supporting electrolyte were changed as shown in Table 8. The secondary batteries of Comparative Examples 7 to 10 were configured using a polymer electrolyte as a binder for the positive electrode active material. Evaluation results such as rate characteristics are shown in Table 8.

[0183] [Comparative Examples 11 to 14] Secondary batteries according to Comparative Examples 11 to 14 were fabricated in the same manner as in Example 37, except that the types and amounts of polyether mono(meth)acrylate, polyether di(meth)acrylate, ionic compound, and supporting electrolyte were changed as shown in Table 8. The secondary batteries of Comparative Examples 11 to 14 were configured using a polymer electrolyte as a positive electrode active material binder, bulk electrolyte, and negative electrode active material binder. Evaluation results such as rate characteristics are shown in Table 8.

[0184] The obtained polymer electrolytes and secondary batteries according to Examples 1 to 40 and Comparative Examples 1 to 14 were evaluated in the same manner as in Example 1. The evaluation results are shown in Tables 5-1, 5-2, 6, 7, and 8.

[0185]

[0186] In Tables 5-1, 5-2 and 6, Mpo% is the ratio of the average number of moles added Mpo to the average number of moles added Meo.

[0187]

[0188] The polymer electrolytes according to Examples 1 to 32 have a structure of Formula (4) in addition to the structure of Formula (1) and at least one of the structures of Formulas (2) and (3) in the polymer structure, and have a volume swelling ratio of 30 to 120%. Therefore, they exhibit high ionic conductivity at both 25°C and 5°C. Furthermore, secondary batteries using the polymer electrolytes according to Examples 1 to 32 as bulk electrolytes have both high rate characteristics and high impact resistance at high temperatures. Furthermore, the polymer electrolytes according to Examples 1 to 32 have a volume swelling ratio of 30 to 120% and an A / (A+B) ratio of 0.50 or greater, which allows for a large number of cycles before a short circuit occurs, resulting in a long-life secondary battery.

[0189] Furthermore, Examples including Example 7, in which the mass ratio α:β of the content A of the structure of formula (1) to the content B of formula (2) in the polymer structure was 70:30 to 98:2, m1+n1 in formula (1-1) was 14 to 58, and m2+n2 in formula (2-1) was 14 to 58, exhibited particularly high ionic conductivity and the rate characteristics of the secondary battery were also good.

[0190] On the other hand, the polymer electrolytes according to Comparative Example 1, which did not have the structure of Formula (4) in the polymer structure, Comparative Examples 2 and 6, which did not have the structure of Formula (1), and Comparative Example 3, which had a volume swelling ratio of less than 30%, had low ionic conductivity and resulted in very poor rate characteristics of the secondary battery. Furthermore, in Comparative Examples 2 to 6, in which A / (A+B) was less than 0.50, the number of cycles until a short circuit occurred was also low, and dendrites were observed on the surface of the battery electrode.

[0191] Furthermore, the secondary batteries using the polymer electrolytes according to Comparative Examples 4 and 5, which had a volume swelling rate of more than 120% or which had no three-dimensional cross-linking, showed a significant decrease in impact resistance at high temperatures.

[0192]

[0193]

[0194] The secondary batteries according to Examples 33 to 36, in which the polymer electrolyte of the present disclosure was used as a positive electrode active material binder, and the secondary batteries according to Examples 37 to 40, in which the polymer electrolyte was used as a positive electrode active material binder, bulk electrolyte, or negative electrode active material binder, had both high rate characteristics and high impact resistance at high temperatures, similar to the case where the polymer electrolyte was used as a bulk electrolyte.

[0195] On the other hand, the secondary batteries according to Comparative Examples 8 and 11, which did not have the structure of Formula (4) in the polymer structure, Comparative Examples 9 and 10, which did not have the structure of Formula (1), and Comparative Example 12, which had a volume swelling ratio of less than 30%, showed poor rate characteristics. Furthermore, the secondary batteries according to Comparative Examples 13 and 14, which had a volume swelling ratio of more than 120 or did not have three-dimensional crosslinks, showed a significant decrease in impact resistance at high temperatures.

[0196] The present disclosure is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the present disclosure. Therefore, the following claims are appended to clarify the scope of the present disclosure. This application claims priority based on Japanese Patent Application No. 2023-127680 filed on August 4, 2023, Japanese Patent Application No. 2024-100598 filed on June 21, 2024, and Japanese Patent Application No. 2024-110667 filed on July 10, 2024, the entire contents of which are incorporated herein by reference.

[0197] 1: Secondary battery, 2: Positive electrode current collector, 3: Positive electrode active material, 4: Positive electrode active material binder, 5: Conductive additive, 6: Positive electrode, 7: Bulk electrolyte, 8: Negative electrode active material, 9: Negative electrode current collector, 10: Negative electrode, 11: Negative electrode active material binder

Claims

1. A polymer electrolyte comprising: a polymer and an alkali metal salt; the alkali metal salt comprises an alkali metal salt having at least one anion selected from the group consisting of bis(trifluoromethanesulfonyl)imide, bis(fluorosulfonyl)imide and hexafluorophosphate; the polymer has a structure represented by the following formula (1); at least one structure selected from the group consisting of a structure represented by the following formula (2) and a structure represented by the following formula (3); and a structure represented by the following formula (4); wherein A is the total number of moles of the anions in the alkali metal salt contained per unit mass of the polymer electrolyte, and B is the number of moles of sulfonylimide groups bonded to the polymer, and A and B satisfy the relationship represented by the following formula (X): 0.50≦A / (A+B) ... (X); and the volume swelling ratio of the polymer electrolyte measured by a methyl ethyl ketone immersion method is 30 to 120%. (In formula (1), R １ represents a hydrogen atom or a methyl group. ２ R represents a linear or branched alkylene group having 1 to 6 carbon atoms. ３ represents an alkyl group having 1 to 6 carbon atoms. ４ R each independently represents a hydrogen atom or a methyl group. ５ and R ６ Each independently represents a linear or branched alkylene group having 1 to 6 carbon atoms. ７ R each independently represents a hydrogen atom or a methyl group. ８ , R ９ and R １０ R each independently represents a linear or branched alkylene group having 1 to 6 carbon atoms. １１ represents a trivalent organic group having 1 to 6 carbon atoms. A1, B1, D1, D2, and D3 in formulas (1) to (3) each independently represent at least (-CH ２ CH ２ It is a linking group having an ethylene oxide structure represented by the formula: (In formula (4), R １２ represents a hydrogen atom or a methyl group. １３ represents a divalent linking group. １４ represents a fluorine atom or a perfluoroalkyl group having 1 to 4 carbon atoms. ＋ represents at least one selected from the group consisting of a lithium ion, a sodium ion and a potassium ion. The sulfonylimide group represents a functional group represented by the following formula (S). In formula (S), R represents a fluorine atom or a perfluoroalkyl group having 1 to 4 carbon atoms.

2. The polymer electrolyte according to claim 1, wherein A and B satisfy 0.65≦A / (A+B)≦0.

96.

3. The polymer electrolyte according to claim 1 or 2, wherein the average number of moles Meo of the ethylene oxide structure added per mole of the (meth)acryloyl residue in the polymer is 2.5 moles or more.

4. A1, B1, D1, D2 and D3 each independently represent (-CH ２ CH (CH ３ 4. The polymer electrolyte according to claim 1, further comprising a propylene oxide structure represented by the formula:

5. The polymer electrolyte according to claim 4, wherein in the polymer, an average number of moles Mpo of the propylene oxide structure added per mole of a (meth)acryloyl residue is 5 to 25% of an average number of moles Meo of the ethylene oxide structure added per mole of a (meth)acryloyl residue.

6. The polymer electrolyte according to any one of claims 1 to 5, wherein the mass ratio α:β is from 70:30 to 98:2, where α is the content by mass of the structure represented by formula (1) in the polymer contained in the polymer electrolyte, and β is the total content by mass of the structure represented by formula (2) and the structure represented by formula (3).

7. The polymer electrolyte according to any one of claims 1 to 6, wherein the structure represented by formula (1) is a structure represented by the following formula (1-1), the structure represented by formula (2) is a structure represented by the following formula (2-1), and the structure represented by formula (3) is a structure represented by the following formula (3-1). (In formula (1-1), R １ represents a hydrogen atom or a methyl group. ２ R represents a linear or branched alkylene group having 1 to 6 carbon atoms. ３ represents an alkyl group having 1 to 6 carbon atoms. m1 and n1 are the average number of moles added, m1 represents an integer of 1 or more, and n1 represents an integer of 0 or more. (-CH ２ -CH ２ -O-) and (-CH ２ -CH(CH ３ The arrangement of the propylene oxide structure represented by the formula (I)-O-) may be a block copolymer or a random copolymer. (In formula (2-1), R ４ R each independently represents a hydrogen atom or a methyl group. ５ , R ６ each independently represents a linear or branched alkylene group having 1 to 6 carbon atoms; m2 and n2 represent the average number of moles added, m2 represents an integer of 1 or more, and n2 represents an integer of 0 or more. (-CH ２ -CH ２ -O-) and (-CH ２ -CH(CH ３ The arrangement of the propylene oxide structure represented by -O-) may be a block copolymer or a random copolymer. The chain sandwiched between two -COO- may further contain a diol structure having 1 to 6 carbon atoms. (In formula (3-1), R ７ R each independently represents a hydrogen atom or a methyl group. ８ , R ９ , R １０ R each independently represents a linear or branched alkylene group having 1 to 6 carbon atoms. １１ represents a trivalent organic group having 1 to 6 carbon atoms. m3 and n3 are the average number of moles added, each m3 independently represents an integer of 1 or more, and each n3 independently represents an integer of 0 or more. (-CH ２ -CH ２ -O-) and (-CH ２ -CH(CH ３ The arrangement of the propylene oxide structure represented by -O-) may be a block copolymer or a random copolymer. The chain sandwiched between -COO- and R11 may further contain a diol structure having 1 to 6 carbon atoms.

8. The polymer electrolyte according to claim 7, wherein, in the polymer electrolyte, m1+n1 in the formula (1-1) is 14 to 58, and m2+n2 in the formula (2-1) and / or m3+n3 in the formula (3-1) is 14 to 58.

9. The polymer electrolyte according to claim 7 or 8, wherein in the polymer electrolyte, m1:n1 in the formula (1-1) is 80:20 to 95:5, and m2:n2 in the formula (2-1) and / or m3:n3 in the formula (3-1) is 80:20 to 95:

5.

10. The polymer electrolyte according to any one of claims 1 to 9, wherein the content of the structure represented by formula (4) in the polymer electrolyte is 1 to 25 parts by mass, relative to a total of 100 parts by mass of the structure represented by formula (1), the structure represented by formula (2), and the structure represented by formula (3).

11. The polymer electrolyte according to any one of claims 1 to 10, wherein the polymer electrolyte is a dry polymer electrolyte.

12. A secondary battery comprising a positive electrode, a bulk electrolyte, and a negative electrode, wherein at least one selected from the group consisting of the positive electrode, the bulk electrolyte, and the negative electrode contains the polymer electrolyte according to any one of claims 1 to 11.

13. A secondary battery comprising a positive electrode, a bulk electrolyte, and a negative electrode, the secondary battery being characterized in that it satisfies at least any one of the following (i) to (iii): (i) the positive electrode has a positive electrode active material and a positive electrode active material binder that fixes the positive electrode active material, the positive electrode active material binder being the polymer electrolyte according to any one of claims 1 to 11; (ii) the bulk electrolyte is the polymer electrolyte according to any one of claims 1 to 11; (iii) the negative electrode has a negative electrode active material and a negative electrode active material binder that fixes the negative electrode active material, the negative electrode active material binder being the polymer electrolyte according to any one of claims 1 to 11.

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