POLYMER ELECTROLYTE AND SECONDARY BATTERY

Abstract

A polymer electrolyte exhibits high mechanical strength and high ionic conductivity even at high temperatures and can minimize the occurrence of dendrites at the interface between a polymer electrolyte and a battery negative electrode. The polymer electrolyte contains a polymer having a specific free terminal polyether structure, a specific cross-linked polyether structure, and a specific fluorosulfonylimide anion group; the polymer electrolyte contains a specific amount of a specific alkali metal salt; and the volume swelling ratio of the polymer electrolyte, determined by a methyl ethyl ketone immersion method, is 30% to 120%.

Description

TECHNICAL FIELD

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

[0002] In recent years, the development of portable devices such as tablets, smartphones, and electric vehicles has led to an increasing demand for secondary batteries as their power sources. Generally, secondary batteries consist of electrodes (a positive and a negative electrode) and an electrolyte. They are charged and discharged as ions move between the electrodes and the electrolyte. Such secondary batteries are used in a wide range of applications, from small devices like mobile phones to large devices like electric vehicles. Therefore, increased safety and further performance improvements are necessary.

[0003] To further improve the safety of secondary batteries, work is currently underway on the development of solid-state secondary batteries, in which conventional flammable electrolyte solutions are replaced by solid electrolytes. Sulfide-based, oxide-based, and polymer-based materials are widely investigated as solid electrolytes.

[0004] To improve the charging and discharging characteristics of secondary batteries, it is generally important to increase the interface between the active material in the electrodes and the electrolyte. The active material is a substance involved in the reaction that generates electricity. While sulfide-based and oxide-based solid electrolytes exhibit excellent ionic conductivity, increasing the interface with the active material is difficult, and they may lack sufficient impact resistance. Therefore, the use of flexible solid electrolytes, such as gel electrolytes, which combine electrolyte solutions and polymers, has been proposed.

[0005] PTL 1 describes a gel electrolyte containing a polyether and an ionic liquid. PTL 2 additionally describes a gel electrolyte in which the affinity for an electrolyte solution is improved by incorporating a quaternary ammonium base into the main chain. PTL 3 additionally describes a dry polymer electrolyte containing a glymer and a lithium salt. COUNTERPOINT LIST PATENT LITERATURE [PTL 1] Japanese patent application no. 2017-090677 [PTL 2] WO 2004 / 027789 [PTL 3] Japanese patent application no. 2009-104891 SUMMARY OF THE INVENTIONAL PROBLEM

[0006] In recent years, lithium-ion secondary batteries have been required to demonstrate not only greater safety but also further improved charging and discharging characteristics. When a polymer gel, such as that used in PTL 1 and PTL 2, is employed as the electrolyte, its strength can decrease at high temperatures, and there is a risk of short circuits due to impact. Additionally, in the dry polymer system of PTL 3, it is necessary to form a lithium-ion complex with a glyme, which is an organic solvent, to achieve high ionic conductivity. It is known that lithium salts coordinated with a glyme form ionic liquids and inherently exhibit the same problems as liquid electrolytes.

[0007] Furthermore, dendrites form at the interface between the electrolyte and the metal negative electrode in secondary batteries, which can lead to a shortened lifespan. Among negative electrode materials for secondary batteries, metal negative electrodes exhibit the highest charge capacity density, and their practical applications are expected to improve energy density. Since the use of metal negative electrodes is considered to significantly improve the performance of secondary batteries, it is important to minimize dendrite formation. Additionally, if dendrite growth progresses, there is a risk of damage to the base materials and packaging materials from which the batteries are constructed, raising safety concerns.

[0008] Therefore, there is a need for polymer electrolytes that: ▪ minimize the decrease in impact resistance even at high temperatures and the risk of short circuits, ▪ exhibit excellent ionic conductivity and ▪ have a long lifespan.

[0009] At least one aspect of the present disclosure provides a polymer electrolyte that exhibits high mechanical strength and high ionic conductivity even at high temperatures and can minimize the formation of dendrites at the interface between a polymer electrolyte and a battery negative electrode. Additionally, at least one aspect of the present disclosure provides a secondary battery that exhibits high impact resistance and excellent battery performance even in high-temperature environments. SOLUTION TO THE PROBLEM

[0010] According to at least one aspect of the present disclosure, a polymer electrolyte is provided, wherein the polymer electrolyte contains a polymer and an alkali metal salt, the alkali metal salt includes an alkali metal salt which, as an anion, contains at least one selected from the group consisting of bis(trifluoromethanesulfonyl)imide, bis(fluorosulfonyl)imide and hexafluorophosphate, the polymer 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), If the total number of moles of anions in the alkali metal salt contained per unit mass of the polymer electrolyte is A and the number of moles of sulfonylimide groups bonded to the polymer is B, then A and B satisfy the relationship of the following formula (X), 0.50≤A / (A+B) and the volume swelling ratio of the polymer electrolyte, determined by a methyl ethyl ketone immersion process, is 30% to 120%:

[0011] (In formula (1) R 1 a hydrogen atom or a methyl group. R 2 is a linear or branched alkylene group containing 1 to 6 carbon atoms. R 3 is an alkyl group that has 1 to 6 carbon atoms.

[0012] In formula (2) R 4 Each independently contains either a hydrogen atom or a methyl group. R 5 and R 6 Each is independently a linear or branched alkylene group containing 1 to 6 carbon atoms.

[0013] In formula (3) R 7 Each independently contains either a hydrogen atom or a methyl group. R 8 , R 9 and R 10 Each is independently a linear or branched alkylene group containing 1 to 6 carbon atoms. R 11is a trivalent organic group that has 1 to 6 carbon atoms.

[0014] In formulas (1) to (3) A1, B1, D1, D2 and D3 are each independently a group of compounds that has at least one ethylene oxide structure represented by (-CH2CH2-O-).

[0015] (In formula (4) R 12 a hydrogen atom or a methyl group. R 13 is a divalent compound group. R 14 is a fluorine atom or a perfluoroalkyl group containing 1 to 4 carbon atoms. X + is at least one selected from the group consisting of a lithium ion, a sodium ion and a potassium ion.

[0016] The sulfonylimide group is a functional group represented by the following formula (S).

[0017] In formula (S), R is a fluorine atom or a perfluoroalkyl group having 1 to 4 carbon atoms.

[0018] Additionally, according to at least one aspect of the present disclosure, a secondary battery comprising a positive electrode, a bulk electrolyte and a negative electrode, wherein at least one of 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. ADVANTAGEOUS EFFECTS OF THE INVENTION

[0019] According to at least one aspect of the present disclosure, it is possible to obtain a polymer electrolyte that exhibits high mechanical strength and high ionic conductivity even at high temperatures and can minimize the formation of dendrites at the interface between a polymer electrolyte and a battery negative electrode. Additionally, according to at least one aspect of the present disclosure, it is possible to obtain a secondary battery that exhibits high impact resistance and excellent battery performance even in high-temperature environments. BRIEF DESCRIPTION OF THE DRAWINGS [ Fig. 1] Fig. Figure 1 is a schematic cross-sectional view of a secondary battery that uses a polymer electrolyte of the present disclosure as a bulk electrolyte. [ Fig. 2] Fig.Figure 2 is a schematic cross-sectional view of a secondary battery which uses the polymer electrolyte of the present disclosure as an active material binder of the positive electrode. [ Fig. 3] Fig. Figure 3 is a schematic cross-sectional view of a secondary battery which uses the polymer electrolyte of the present disclosure as an active material binder of the positive electrode, a bulk electrolyte and an active material binder of the negative electrode. DESCRIPTION OF THE EXECUTION FORMS

[0020] In this disclosure, unless otherwise specified, the descriptions "from XX to YY" and "XX to YY," which represent a range of numbers, mean a range of numbers that includes a lower bound and an upper bound, which are endpoints. If the ranges of numbers are expressed in steps, the upper and lower bounds of the ranges can be combined arbitrarily. Additionally, in this disclosure, for example, a description such as "at least one, selected from the group consisting of XX, YY, and ZZ" means one of XX, YY, ZZ, a combination of XX and YY, a combination of XX and ZZ, a combination of YY and ZZ, and a combination of XX, YY, and ZZ. If XX is a group, a plurality of XX can be selected, and the same applies to YY and ZZ.

[0021] The inventors conducted extensive investigations to obtain a polymer electrolyte that exhibits high mechanical strength and high ionic conductivity even at high temperatures and minimizes the occurrence of dendrites at the interface between the polymer electrolyte and a battery negative electrode.

[0022] Initially, the inventors determined that in dry polymer systems, where excitation of lithium ion movement by a liquid electrolyte is not expected, the ionic conductivity can be increased by using a polyether-modified (meth)acrylic resin that has a specific 3D cross-linking structure.

[0023] Therefore, the inventors conducted further investigations into the polyether-modified (meth)acrylic resin. As a result, they found that when an anionic functional group, comprising at least one selected from the group consisting of a fluorosulfonylimide (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 + When combined as a counterion (cation) of the anionic functional group, it is possible to obtain a polymer electrolyte that can achieve a high ionic conductivity and transport number of the specific cations even at low temperatures.

[0024] That is to say, the polymer electrolyte of the present disclosure fulfills the following conditions. ▪ The 3D cross-linked structure of the polymer has many free terminal chains that are not bound at one end to another polymer chain (the structure of formula (1)), resulting in a very low cross-linking density (volume swelling ratio). ▪ The 3D cross-linked structure of the polymer contains an anionic functional group comprising a fluorinated sulfonylimide group or a perfluoroalkylsulfonylimide group and a cation (the structures of formula (2) and / or formula (3) and the structure of formula (4)).

[0025] Additionally, the polymer electrolyte contains a polymer that has the anionic functional group in its molecule and an alkali metal salt, which is an electrolyte (supporting electrolyte) that is not bound to the polymer in a specific ratio (formula (X)). Therefore, it is possible to minimize the occurrence of dendrites.

[0026] The inventors suggest that the reason why the polymer electrolyte exhibits high ionic conductivity without relying on a liquid electrolyte, according to one aspect of the present disclosure, is as follows.

[0027] In dry polymer systems, where stabilization of ions such as lithium ions by a liquid electrolyte is not possible, the ions move between molecularly mobile polymer chains. Therefore, polymer systems that are three-dimensionally cross-linked to minimize the risk of short circuits due to film deformation at high temperatures are more susceptible to steric hindrance compared to liquid systems.

[0028] However, the polymer used in the present disclosure has a 3D cross-linked structure (the structures of formula (2) and / or formula (3)) and is less likely to deform even at high temperatures. On the other hand, the polymer has a free terminal chain in its structure (the structure of formula (1)) which is not bonded to another polymer chain at one end. Accordingly, the polymer is assumed not to form a dense network structure, which makes it less likely that ion movement will be inhibited while maintaining its strength.

[0029] Additionally, the fluorosulfonylimide or perfluoroalkylsulfonylimide structure bonded to the polymer makes it less likely that ion movement will be inhibited, and makes it possible to provide an electrolyte with a high ion transport number.

[0030] Additionally, the fluorosulfonylimide or perfluoroalkylsulfonylimide structure bonded to the polymer minimizes stereoregularity and reduces polymer crystallinity. Therefore, it is assumed that a decrease in ionic conductivity at low temperatures is also minimized.

[0031] Additionally, the anionic group, which has a fluorosulfonylimide or perfluoroalkylsulfonylimide structure bonded to the polymer, and a cation (the structure of formula (4)) make the polymer highly polar. Therefore, even in systems to which a supporting electrolyte such as a lithium salt is added, the supporting electrolyte is not precipitated, and the amount of supporting electrolyte that can be dissolved can be increased.

[0032] Additionally, by using an alkali metal salt as a supporting electrolyte, it is possible to minimize a local increase in the concentration of ions such as lithium ions near the metal negative electrode. This is presumably due to the fact that free anions, which have a higher degree of dissociation than immobilized anions, move through the polymer and thus minimize the interaction between the immobilized anionic groups and the ions, balancing the ion concentration distribution. Particularly when free anions are present in a region satisfying the following formula (X): 0.50 ≤ A / (A + B), it is possible to minimize ion localization.

[0033] Dendrite growth is caused by the local aggregation of ions, such as lithium ions, in the electrolyte. Therefore, delocalizing the ion distribution can minimize dendrite formation and extend the lifespan of the secondary battery. The polymer used in this disclosure is designed to have a very low cross-linking density, allowing free anions to move freely. This ease of movement is thought to make the effect of delocalizing the ion distribution more pronounced.

[0034] The 3D cross-linked structure of the polymer exhibits many free terminal chains, each not bonded to another polymer chain at one end. This results in a very low cross-linking density, which is clearly reflected in the volume swelling ratio of the polymer electrolyte, determined by a methyl ethyl ketone immersion process. Specifically, the volume swelling ratio of the polymer electrolyte using methyl ethyl ketone (MEK) ranges from 30% to 120%.

[0035] The volume swelling ratio is the ratio of the volumes of a 3D cross-linked polymer before and after immersion in a specific solvent and saturation. The volume swelling ratio is calculated using the following formula, and the volume of a test specimen is calculated from its weight in air and its weight in water. Specific measurement procedures are described below. Volume swelling ratio (%) = (Volume when saturated by immersion in solvent and swelling) / (Volume before immersion in solvent) × 100

[0036] If the volume swelling ratio of the polymer electrolyte is less than 30%, it is assumed that there are few free terminal chains (the structure of formula (1)) and many 3D cross-linked structures. Therefore, the ionic conductivity is low and the charging rate of the secondary battery is likely to be low. Additionally, due to the many 3D cross-linked structures, it is difficult to achieve the effect of delocalizing the ion distribution, and dendrites are formed.

[0037] On the other hand, if the volume swelling ratio of the polymer electrolyte is more than 120%, this indicates that the number of 3D cross-linked structures is insufficient, so a decrease in strength, such as a decrease in impact strength at high temperatures, is likely to occur.

[0038] 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%.

[0039] Preferred embodiments of the present disclosure are described in detail below with reference to the drawings. The components, materials, shapes, relative arrangements thereof, and the like described in these embodiments do not limit the scope of the present disclosure. (1) Form of the secondary battery

[0040] The 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.

[0041] Fig. 1, Fig. 2 to Fig. Figure 3 shows an example of a secondary battery that uses the polymer electrolyte of the present disclosure. One in Fig. Figure 1 of the secondary battery shows a schematic configuration example of a secondary battery that uses a polymer electrolyte as a bulk electrolyte 7. An active material of the positive electrode 3, provided on a current collector of the positive electrode 2, is fixed by an active material binder of the positive electrode 4 to form a positive electrode 6. The positive electrode 6 may contain a conductivity aid 5.

[0042] An active material of the negative electrode 8, which is provided on a current collector of the negative electrode 9, forms a negative electrode 10. In Fig. 1 is the active material of the negative electrode, metallic lithium, indium, or the like. The bulk electrolyte 7 is provided between the positive electrode 6 and the negative electrode 10.

[0043] The in Fig. Secondary battery 1 shown in Figure 2 is a schematic configuration example of a secondary battery that uses a polymer electrolyte as the active material binder of the positive electrode 4. In the configuration of Fig.2. The positive electrode 6 contains a polymer electrolyte. For example, the positive electrode 6 contains the active material of the positive electrode 3 and the active material binder of the positive electrode 4, which fixes the active material of the positive electrode, and the active material binder of the positive electrode 4 is the polymer electrolyte of the present disclosure. In the configuration in Fig. 2 is the bulk electrolyte 7, an oxide-based or sulfide-based inorganic solid electrolyte. The other configurations are the same as those in Fig. 1.

[0044] The in Fig. Figure 3 of the secondary battery 1 shows a schematic configuration example of a secondary battery that uses a polymer electrolyte as the active material binder of the positive electrode 4, the bulk electrolyte 7, and an active material binder of the negative electrode 11. In the aspect of Fig.3. The positive electrode, the bulk electrolyte, and the negative electrode contain a polymer electrolyte. That is, the positive electrode 6 contains the active material of the positive electrode 3 and the active material binder of the positive electrode 4, which fixes the active material of the positive electrode, and the active material binder of the positive electrode 4 is the polymer electrolyte of the present disclosure. Additionally, the bulk electrolyte 7 is the polymer electrolyte of the present disclosure. Additionally, the negative electrode 10 contains the active material of the negative electrode 8 and the active material binder of the negative electrode 11, which fixes the active material of the negative electrode 8, and the active material binder of the negative electrode 11 is the polymer electrolyte of the present disclosure. In the configuration of Fig. 3. The active material of the negative electrode 8 is a carbon material such as graphite. The other configurations are the same as those in Fig. 1.

[0045] In order to achieve the effects of the present disclosure more effectively, it is, as in Fig. 1 and Fig. 3 shown, advantageously that the bulk electrolyte 7 is a polymer electrolyte which penetrates the active material of the positive electrode 3 and the active material of the negative electrode 8, resulting in an increase in the contact area. Method for manufacturing a solid-state secondary battery

[0046] Solid-state secondary batteries can be manufactured using known cell formation techniques, such as the formation of laminate cells, button cells, and pressure cells. A laminate cell type is described below.

[0047] A laminate is obtained in which a positive electrode, a bulk electrolyte, and a negative electrode are arranged between the current collectors of the positive and negative electrodes. Electrode tabs are welded to the current collectors of the positive and negative electrodes. The laminate, in which the current collector of the positive electrode, the positive electrode, the bulk electrolyte, the negative electrode, and the current collector of the negative electrode are laminated in that order, is wrapped with an aluminum laminate film and sealed under reduced pressure using a vacuum packaging machine. Once the ends of the electrode tabs are exposed outside the laminate film and the tabs and the aluminum laminate film are joined by thermocompression welding, a seal is created.After sealing, pressurization can be performed if necessary using an isostatic pressure device or similar equipment. Examples of bulk electrolytes include solid electrolytes and polymer electrolytes, but both can be used to form a laminate. In addition to the laminate mentioned above, other layers, such as an elastic material and a resin material, can be laminated within the aluminum laminate foil, taking into account strength and formability. A bipolar type can also be used, in which a variety of laminates are bonded together. Current collector of the positive electrode

[0048] Examples of positive electrode current collectors include metal foils. Examples of metals include aluminum, stainless steel, copper, silver, gold, platinum, nickel, and palladium. The metals can be used individually, or two or more can be used in combination. Active material of the positive electrode

[0049] The active material for the positive electrode can be, for example, materials commonly used in secondary batteries such as lithium-ion batteries. Examples include (CF) m , (C2F) m , MnO2, TiS2, MoS2, FeS2, Li x ACoO2, Li x ANiO2, Li x AMnO2, Li x ACoyNi 1-y O2, Li x ACo y M 1-y O z , Li x ANi 1-y M y O z , Li x BMn2O4, Li x BMn 2-y M yO4 (in the formulas, M is 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 and z = 2.0 to 2.3), vanadium oxide and lithium compounds thereof, niobium oxide and lithium compounds thereof, conjugated polymers using organic conductive substances, and olivine compounds.

[0050] Here, the xA and xB values ​​in the above composition ratios are values ​​before the start of charging and discharging and increase or decrease accordingly. The active materials of the positive electrodes can be used individually, or two or more can be used in combination. Conductivity aids

[0051] Conductivity aids can include materials commonly used in secondary batteries such as lithium-ion batteries. Examples include graphites such as natural and synthetic graphite, carbon blacks such as acetylene carbon black, ketone carbon black, gas carbon black, furnace carbon black, lamp carbon black, and thermal carbon black, conductive fibers such as carbon fibers and metal fibers, metal powders such as aluminum powder, conductive whiskers such as zinc oxide whiskers and potassium titanate whiskers, conductive metal oxides such as titanium dioxide, and organic conductive materials such as phenylene derivatives. These conductivity aids can be used individually or in combination. Active material binder

[0052] The active material binder can be, for example, those commonly used in secondary batteries such as lithium-ion batteries. Examples include polyvinylidene fluoride (PVDF), polytetrafluoroethylene, polyethylene, polypropylene, aramid resin, polyamide, polyimide, polyamide-imide, 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 carboxymethylcellulose.

[0053] The polymer electrolyte of the present disclosure can be used as a bulk electrolyte, can be used as an active material binder of the positive electrode, or can be used as an active material binder of the negative electrode, or can be used as a bulk electrolyte, an active material binder of the positive electrode and an active material binder of the negative electrode.

[0054] That is, the secondary battery preferably fulfills at least one of the following (i) to (iii). (i) The positive electrode 6 contains the active material of the positive electrode 3 and the active material binder of the positive electrode 4, which fixes the active material of the positive electrode, and the active material binder of the positive electrode 4 is the polymer electrolyte of the present disclosure. (ii) The bulk electrolyte 7 is the polymer electrolyte of the present disclosure. (iii) The negative electrode 10 contains the active material of the negative electrode 8 and the active material binder of the negative electrode 11, which fixes the active material of the negative electrode 8, and the active material binder of the negative electrode 11 is the polymer electrolyte of the present disclosure.

[0055] Using the polymer electrolyte of the present disclosure as an active material binder of the positive electrode is particularly preferred because lithium ions can easily penetrate from the surface to the deeper part of the positive electrode 6. The active material binders can be used individually, or two or more of them can be used in combination.

[0056] The positive electrode 6 can be produced, for example, by press-fitting a positive electrode mixture onto the surface of the current collector of the positive electrode 2, or by applying a positive electrode mixture slurry, drying, and, if necessary, rolling to form the positive electrode 6. It can also be produced by kneading the active material of the positive electrode, the conductivity aid, and the active material binder of the positive electrode. The positive electrode mixture slurry can also be produced, for example, by dissolving or dispersing the active material of the positive electrode, the conductivity aid, and the active material binder in a medium such as dehydrated N-methyl-2-pyrrolidone, acetonitrile, methyl ethyl ketone, or ethylene glycol ethers. Current collector of the negative electrode

[0057] Examples of negative electrode current collectors include metal foils. Examples of metals include aluminum, stainless steel, copper, silver, gold, platinum, nickel, and palladium. The metals can be used individually, or two or more can be used in combination. Active material of the negative electrode

[0058] Examples of active materials for the negative electrode include metals, metal fibers, carbon materials, oxides, nitrides, silicon, silicon compounds, tin, tin compounds, and various alloy materials. Among these, metals, oxides, carbon materials, silicon, silicon compounds, tin, tin compounds, and the like are preferred, taking into account their capacitance density.

[0059] Examples of metals include metallic Li and In-Li, and examples of oxides include Li4Ti5O 12(LTO: Lithium titanate). Examples of carbon materials include various natural graphites, coke, partially graphitized carbon, carbon fibers, spherical carbon, various synthetic 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 are SnO₂. B (0 <B<2), SnO2, SnSiO3, Ni2Sn4 und Mg2Sn.

[0060] Additionally, the negative electrode material can contain a conductivity enhancer. Examples of conductivity enhancers include graphites such as natural and synthetic graphite, and carbon blacks such as acetylene carbon black, Ketjen carbon black, gas carbon black, furnace carbon black, lamp carbon black, and thermal carbon black. If the polymer electrolyte is used as the bulk electrolyte, graphite can be particularly preferred as the active material of the negative electrode.

[0061] Examples of conductivity aids include conductive fibers such as carbon fibers, carbon nanotubes and metal fibers, metal powders such as fluorocarbon and aluminum, conductive whiskers such as zinc oxide, conductive metal oxides such as titanium dioxide and organic conductive materials such as phenylene dielectrics. Solid electrolyte

[0062] In a secondary battery, the solid electrolyte is arranged as a lithium-ion moving layer between the positive and negative electrodes and can be used as a bulk electrolyte that also acts as a separator. Additionally, it can also be used as an additive that improves the conductivity of lithium ions by being mixed into the active material layers of the positive and negative electrodes.

[0063] The polymer electrolyte of the present disclosure can be suitablely used both as a bulk electrolyte and as an auxiliary material. Accordingly, it is possible to increase the contact area between the bulk electrolyte and the active material of the positive electrode and the active material of the negative electrode, and it also provides flexibility that allows it to adapt to the expansion and contraction of the active material of the positive electrode and the active material of the negative electrode, and thus it is possible to improve the properties of the secondary battery.

[0064] Additionally, when the polymer electrolyte of the present disclosure is used as a bulk electrolyte, it is easier to demonstrate the effect of minimizing the occurrence of dendrites. Therefore, the bulk electrolyte is preferably the polymer electrolyte of the present disclosure.

[0065] A solid electrolyte other than the polymer electrolyte can be used for the bulk electrolyte and the auxiliary material. Examples of solid electrolytes other than the polymer electrolyte include oxide-based solid electrolytes, sulfide-based solid electrolytes, and complex hydride-based solid electrolytes.

[0066] Examples of oxide-based solid electrolytes include nasicon-type compounds such as Li 1,5 Al 0,5 Ge 1,5 (PO4)3 and Li 1,3 Al 0,3 Ti 1,7 (PO4)3 and garnet-type compounds such as Li 6,25 LA3ZR2Al 0,25 O 12 Additionally, examples of oxide-based solid electrolytes include perovskite-type compounds such as Li 0,33 Li 0,55 TiO3. Additionally, examples of oxide-based solid electrolytes include lisicone-type compounds such as Li 14Zn(GeO4)4 and acid compounds such as Li3PO4, Li4SiO4 and Li3BO3. Specific examples of sulfide-based solid electrolytes include Li2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-Li2S-P2O5, LiI-Li3PO4-P2S5 and Li2S-P2S5.

[0067] Additionally, the solid electrolyte can be crystalline or amorphous, or it can be a glass ceramic. Here, the term Li₂S-P₂S₅ refers to a sulfide-based solid electrolyte formed using a raw material containing Li₂S and P₂S₅.

[0068] The polymer electrolyte of the present disclosure can be used as a bulk electrolyte, as an active material binder of the positive electrode, or as an active material binder of the negative electrode. The configuration of the polymer electrolyte according to one embodiment of the present disclosure is described in detail below.

[0069] The polymer electrolyte of the present disclosure is preferably, for example, a solid electrolyte or a semi-solid electrolyte, such as a dry polymer electrolyte or a gel electrolyte. That is to say, a non-liquid electrolyte is preferred. A dry polymer electrolyte is even more preferred. The polymer electrolyte is preferably substantially free of a liquid component, such as a liquid electrolyte. Polymer electrolyte

[0070] A polymer electrolyte according to an embodiment of the present disclosure comprises a polymer having the following structure. The polymer is, for example, a (meth)acrylic polymer. The polymer electrolyte is, for example, a polyetheracrylic resin with a 3D cross-linked structure comprising 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).

[0071] The polymer electrolyte has a structure represented by the following formula (1).

[0072] In formula (1) R 1 a hydrogen atom or a methyl group. R 2 is a linear or branched alkylene group comprising 1 to 6 (preferably 1 to 4 and more, preferably 2 to 4) carbon atoms. R 3 is an alkyl group comprising 1 to 6 (preferably 1 to 4 and more, preferably 1) carbon atoms.

[0073] In formula (1), A1 is a group of compounds that has at least one ethylene oxide structure represented by (-CH2CH2-O-).

[0074] The structure represented by formula (1) is preferably a structure represented by the following formula (1-1).

[0075] In formula (1-1) R 1 a hydrogen atom or a methyl group. R 2 is a linear or branched alkylene group comprising 1 to 6 (preferably 1 to 4 and more, preferably 2 to 4) carbon atoms. R 3 is an alkyl group comprising 1 to 6 (preferably 1 to 4 and more, preferably 1) carbon atoms. m1 and n1 are average numbers of moles added. m1 is an integer of 1 or more (preferably 1 to 110 and more, preferably 13 to 46). n1 is an integer of 0 or more (preferably 5% to 25% of m1 and more, preferably 11% to 25% of m1).

[0076] The polymer electrolyte has at least one structure selected from the group consisting of a structure represented by formula (2) and a structure represented by formula (3). At least one structure selected from the group consisting of a structure represented by formula (2) and a structure represented by formula (3) may be a structure represented by formula (2). A 3D cross-linked structure can be formed with this structure. [C6]

[0077] In formula (2) R 4 Each independently contains either a hydrogen atom or a methyl group. R 5 and R 6 are each independently a linear or branched alkylene group having 1 to 6 (preferably 1 to 4 and more preferably 2 to 4) carbon atoms.

[0078] In formula (3) R 7 Each independently contains either a hydrogen atom or a methyl group. R8 , R 9 and R 10 Each is independently a linear or branched alkylene group comprising 1 to 6 (preferably 1 to 4 and more, preferably 2 to 4) carbon atoms. R 11 is a trivalent organic group comprising 1 to 6 (preferably 1 to 3 and more preferably 1) carbon atoms.

[0079] In formulas (2) and (3), B1, D1, D2 and D3 are each independently a compound group that has at least one ethylene oxide structure represented by (-CH2CH2-O-).

[0080] In formulas (1) to (3), A1, B1, D1, D2 and D3 each preferably independently possess an additional propylene oxide structure represented by (-CH2CH(CH3)-O-). The arrangement of the ethylene oxide structure and the propylene oxide structure can be a block copolymer or a statistical copolymer. A statistical copolymer is preferred.

[0081] Additionally, A1, B1, D1, D2, and D3 may each independently possess a diol structure comprising 1 to 6 (preferably 4 to 6) carbon atoms, provided that the effects of the present disclosure are not impaired. The diol structure is characterized by -OR x -O- represented, where R x an alkylene group that has 1 to 6 (preferably 4 to 6) carbon atoms.

[0082] The structure represented by formula (2) is preferably a structure represented by the following formula (2-1).

[0083] In formula (2-1) R 4 Each independently contains either a hydrogen atom or a methyl group. R 5 and R 6Each independent alkylene group comprises a linear or branched group having 1 to 6 (preferably 1 to 4 and more, preferably 2 to 4) carbon atoms. m2 and n2 are average numbers of moles added, m2 being an integer of 1 or more (preferably 1 to 110 and more, preferably 13 to 46), and n2 being an integer of 0 or more (preferably 5% to 25% of m2 and more, preferably 11% to 25% of m2).

[0084] Provided that the effects of the present disclosure are not impaired, the chain arranged between two -COO- units may additionally have a diol structure with 1 to 6 (preferably 4 to 6) carbon atoms. For example, a diol structure may be provided between ethylene oxide structures, between propylene oxide structures, or between an ethylene oxide structure and a propylene oxide structure. The diol structure is defined by -OR x -O- represented, where R xan alkylene group that has 1 to 6 (preferably 4 to 6) carbon atoms.

[0085] The structure represented by formula (3) is preferably a structure represented by the following formula (3-1).

[0086] In formula (3-1) R 7 Each independently contains either a hydrogen atom or a methyl group. R 8 , R 9 and R 10 Each is independently a linear or branched alkylene group comprising 1 to 6 (preferably 1 to 4 and more, preferably 2 to 4) carbon atoms. R 11is a trivalent organic group (preferably a hydrocarbon group) comprising 1 to 6 (preferably 1 to 3 and more, preferably 1) carbon atoms. m3 and n3 are average numbers of moles added. m3 are each independently an integer of 1 or more (preferably 1 to 110 and more, preferably 13 to 46). n3 are each independently an integer of 0 or more (preferably 5% to 25% of m3 and more, preferably 11% to 25% of m3).

[0087] As long as the effects of the present disclosure are not impaired, the agreement between -COO- and R 11 The arranged chain additionally possesses a diol structure containing 1 to 6 (preferably 4 to 6) carbon atoms. For example, a diol structure can be provided between ethylene oxide structures, between propylene oxide structures, or between an ethylene oxide structure and a propylene oxide structure. The diol structure is defined by -OR x -O- represented, where Rx an alkylene group that has 1 to 6 (preferably 4 to 6) carbon atoms.

[0088] The average number of moles of ethylene oxide structures added per mole of (meth)acryloyl residue in the polymer contained in the polymer electrolyte is preferably 2.5 moles or more. Meo is more preferably 13 to 46. Within the above range, the crosslinking density of the polymer backbone becomes more suitable, high-temperature strength is maintained, and high lithium-ion conductivity is achieved. The (meth)acryloyl residue is a form in which a (meth)acryloyl group has undergone addition polymerization and is represented, for example, by the structure shown in formula (1).

[0089] Additionally, the average number of moles of propylene oxide structures added per mole of (meth)acryloyl residue in the polymer contained in the polymer electrolyte 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. Within the aforementioned range, it is possible to suppress the inhibition of lithium ion migration at low temperatures by minimizing the crystallinity of the poly(methacrylate) backbone, even if the molecular weight between the crosslinking points is large.

[0090] The average number of added moles of Meo and Mpo can be measured by decomposing the polymer electrolyte using pyrolysis-GC / MS and quantifying fragments originating from (meth)acryloyl residues, fragments originating from ethylene oxide structures, and fragments originating from propylene oxide structures using generated calibration curves.

[0091] The average number of added moles of Mpo is preferably 1 to 15 and more, preferably 2 to 10.

[0092] In the polymer electrolyte described above in the present disclosure, the 3D cross-linked structure of the polymer exhibits a very low cross-linking density, and the polymer chains have many free chains that are not bonded to another polymer chain at one end. Such a cross-linked 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 comprising an unsaturated reactive functional group, an anionic functional group comprising a fluorinated sulfonylimide group or a perfluoroalkylsulfonylimide group and a cation (hereinafter referred to as a "fluorosulfonylimide-based ionic compound") Polyether mono(meth)acrylate

[0093] Polyether mono(meth)acrylate can form a structure represented by formula (1) (preferably formula (1-1)). For example, at least one selected from the group consisting of polyethylene glycol mono(meth)acrylate and a mono(meth)acrylate of a polyethylene glycol-propylene glycol copolymer can be used as the polyether mono(meth)acrylate. If a mono(meth)acrylate of a polyethylene glycol-propylene glycol copolymer is used, the molar ratio of the ethylene glycol structure to the propylene glycol structure is preferably 100:0 to 50:50 and more preferably 80:20 to 95:5.

[0094] If the molar ratio of the ethylene glycol structure to the propylene glycol structure is within the above range, the lithium ion transport capacity provided by polyethylene glycol can be maintained at a high level, and in combination with the structure of formula (4) it becomes easier to further minimize the inhibition of lithium ion movement due to the crystallization of the polymer.

[0095] For example, polyether mono(meth)acrylate is represented by the following formula (1').

[0096] In formula (1') R1, R2, R3, m1 and n1 are the same as in formula (1-1). Polyether di(meth)acrylate

[0097] Polyether di(meth)acrylate can form a structure represented by formula (2) (preferably formula (2-1)). For example, at least one selected from the group consisting of polyethylene glycol di(meth)acrylate and a di(meth)acrylate of a polyethylene glycol-propylene glycol copolymer can be used as the polyether di(meth)acrylate. If a di(meth)acrylate of a polyethylene glycol-propylene glycol copolymer is used, the molar ratio of the ethylene glycol structure to the propylene glycol structure is preferably 100:0 to 50:50 and more preferably 80:20 to 95:5.

[0098] If the molar ratio of the ethylene glycol structure to the propylene glycol structure is within the above range, the lithium ion transport capacity provided by polyethylene glycol can be maintained at a high level, and in combination with the structure of formula (4) it becomes easier to further minimize the inhibition of lithium ion movement due to polymer crystallization.

[0099] For example, polyether di(meth)acrylate is represented by the following formula (2').

[0100] In formula (2') R 4 , R 5 , R 6 , m2 and n2 are the same as in formula (2-1).

[0101] Provided that the effects of the present disclosure are not impaired, the chain arranged between two -COO- molecules may additionally have a diol structure comprising 1 to 6 (preferably 4 to 6) carbon atoms. For example, a diol structure may be provided between ethylene oxide structures, between propylene oxide structures, or between an ethylene oxide structure and a propylene oxide structure. The diol structure is defined by -OR. x -O- represented, where R x an alkylene group with 1 to 6 (preferably 4 to 6) carbon atoms. Polyether tri(meth)acrylate

[0102] Polyether tri(meth)acrylate can form a structure represented by formula (3) (preferably formula (3-1)). For example, at least one selected from the group consisting of polyethylene glycol tri(meth)acrylate and a tri(meth)acrylate of a polyethylene glycol-propylene glycol copolymer can be used as the polyether tri(meth)acrylate. If a tri(meth)acrylate of a polyethylene glycol-propylene glycol copolymer is used, the molar ratio of the ethylene glycol structure to the propylene glycol structure is preferably 100:0 to 50:50 and more preferably 80:20 to 95:5.

[0103] If the molar ratio of the ethylene glycol structure to the propylene glycol structure is within the above-mentioned range, the lithium ion transport capacity provided by polyethylene glycol can be maintained at a high level, and in combination with the structure of formula (4) it becomes easier to further minimize the inhibition of lithium ion movement due to polymer crystallization.

[0104] For example, polyethertri(meth)acrylate is represented by the following formula (3').

[0105] In formula (3') R 7 , R 8 , R 9 , R 10 , R 11 , m3 and n3 are the same as in formula (3-1).

[0106] As long as the effects of the present disclosure are not impaired, the agreement between -COO- and R 11The arranged chain additionally possesses a diol structure containing 1 to 6 (preferably 4 to 6) carbon atoms. For example, a diol structure intermediate between the ethylene oxide and propylene oxide structures can be provided. The diol structure is defined by -OR x -O- represented, where R x an alkylene group that has 1 to 6 (preferably 4 to 6) carbon atoms.

[0107] 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.

[0108] In formulas (1-1), (2-1) and (3-1) (as well as formulas (1'), (2') and (3')), the arrangement of an ethylene oxide structure represented by (-CH2-CH2-O-) and a propylene oxide structure represented by (-CH2-CH(CH3)-O-) can be a block copolymer or a statistical copolymer. A statistical copolymer is preferred.

[0109] The mass fraction of the structure represented by formula (1) in the polymer contained in the polymer electrolyte is α. Additionally, the total mass fraction (preferably the fraction of the structure represented by formula (2)) of the structure represented by formula (2) and the structure represented by formula (3) in the polymer is β. The mass ratio α:β (α to β) is preferably 70:30 to 98:2. The mass ratio is more preferably 88:12 to 96:4 and even more preferably 90:10 to 95:5.

[0110] In particular, the mass ratio α:β can be adjusted by the ratio between polyether mono(meth)acrylate and polyether di(meth)acrylate and / or tri(meth)acrylate.

[0111] If the mass ratio α:β is within the above-mentioned range, this is particularly preferred because the polymer does not form an excessively dense network structure and makes it less likely to inhibit the movement of lithium ions while maintaining its strength.

[0112] In the polymer electrolyte, 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 preferably 1 to 110 (more preferably 14 to 58). Within the above range, since the cross-linking density of the polymer main chain is appropriately adjusted, the strength at high temperatures is maintained, the ionic conductivity of the polymer electrolyte is further improved, and the charging rate of the secondary battery is also improved.

[0113] In the polymer electrolyte, 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)) are preferably 80:20 to 95:5 (more preferably 85:15 to 95:5).

[0114] Within the above range, it is possible to further minimize the inhibition of lithium ion migration at low temperatures by minimizing the crystallinity of the polymer main chain, even if the molecular weight between the cross-linking points is large. Fluorosulfonylimide anionic group

[0115] The polymer in the polymer electrolyte has a structure that is represented by the following formula (4).

[0116] In formula (4) R 12 a hydrogen atom or a methyl group. R 13 is a divalent compound group. R 14 is a fluorine atom or a perfluoroalkyl group comprising 1 to 4 (preferably 1 or 2) carbon atoms. X + is a cation and at least one selected from the group consisting of a lithium ion, a sodium ion and a potassium ion.

[0117] The divalent compound group for R 13is preferably a linear or branched alkylene group having 1 to 7 (preferably 2 to 4) carbon atoms. The divalent compound group is preferably -COO-R. 30 - (where the carbonyl group is bonded to a carbon atom, to which R 12 is bound in formula (4). R 30 is preferably a linear or branched alkylene group having 1 to 7 (preferably 2 to 4) carbon atoms.

[0118] Regarding the polyether composition of polyether(meth)acrylates, which are the main components of the polymer, polyethylene glycol is preferred with respect to the transport capacity of ions such as lithium ions. However, since polyethylene glycol exhibits high crystallinity, a process for copolymerizing a propylene glycol structure, which has poor ion transport capacity, is used in a specific ratio to minimize crystallization, particularly at low temperatures. Consequently, it is difficult to achieve high ionic conductivity using only the polyether composition with the structures of formulas (1) to (3).

[0119] On the other hand, crystallinity can be reduced by incorporating the structure of formula (4) into the polymer structure, since formula (4) is an anionic structure with a relatively large molecular size. Therefore, in the polyether composition, it is possible to minimize crystallization at low temperatures, even by reducing the amount of the propylene glycol structure, which has poor lithium ion transport capacity. As a result, high ionic conductivity can be maintained even at low temperatures.

[0120] The content of the structure represented by formula (4) in the polymer, based on a total content 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), 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.

[0121] If the content of formula (4) is within this range, an improvement in ionic conductivity can be expected due to the reduced crystallinity, while still containing a sufficient amount of ions.

[0122] The state after these reactions can be confirmed by analysis using known techniques, for example combustion ion chromatography, pyrolysis-GC / MS, FT-IR and NMR. cation

[0123] The cation X represented by formula (4) + For example, at least one cation is selected from the group consisting of a lithium ion, a sodium ion, and a potassium ion. The cation can be selected depending on the carrier in the secondary battery. For example, lithium is selected for lithium-ion secondary batteries in which lithium cobalt oxide or the like is used as the active material of the positive electrode, and sodium is selected for sodium-sulfur secondary batteries. Supportive electrolyte

[0124] The polymer electrolyte contains an alkali metal salt. This alkali metal salt can serve as a supporting electrolyte. The alkali metal salt comprises an alkali metal salt containing, as an anion, at least one selected from the group consisting of bis(trifluoromethanesulfonyl)imide, bis(fluorosulfonyl)imide, and hexafluorophosphate. Since alkali metal salts containing the above specific anions exhibit a high degree of dissociation, polymer electrolytes utilizing these salts can achieve excellent ionic conductivity.

[0125] The alkali metal salt is preferably, for example, at least one selected from the group consisting of a lithium salt, a sodium salt, and a potassium salt. For example, the lithium salt is at least one selected from the group consisting of LiN(CF3SO2)2, LiN(SO2F)2, and LiPF6.

[0126] The total number of moles of anions, namely bis(trifluoromethanesulfonyl)imide, bis(fluorosulfonyl)imide, and hexafluorophosphate, in the alkali metal salt per unit mass of the polymer electrolyte is A. Additionally, the number of moles of sulfonylimide groups bonded to the polymer is B. In this case, A and B satisfy the relationship of the following formula (X). 0.50≤A / (A+B)

[0127] As described above, fulfilling equation (X) indicates the presence of many free anions, which can minimize ion localization. If A / (A+B) is less than 0.50, the effect of minimizing ion localization cannot be achieved, and dendrites occur.

[0128] The sulfonylimide group is represented by the following formula (S).

[0129] In formula (S) R is a fluorine atom or a perfluoroalkyl group having 1 to 4 (preferably 1 or 2) carbon atoms.

[0130] It is preferred that A and B satisfy 0.65≤A / (A+B)≤0.96.

[0131] Additionally, the alkali metal salt content in the polymer electrolyte is preferably between 5 and 25 parts by mass per 100 parts by mass of the polymer. If A / (A+B) and the content of the supporting electrolyte are within the above ranges, the alkali metal salt exhibits favorable compatibility with the polymer and does not precipitate, high ionic conductivity can be maintained without a significant reduction in the ion transport number, and the formation of dendrites can be further minimized.

[0132] Provided that the effects of the present disclosure are not impaired, the polymer electrolyte may contain other supporting electrolytes in addition to the alkali metal salt mentioned above. Examples of other lithium salts include LiBF4 and LiN(SO2C2F4). s)2, LiAlCl4, LiSBF6, LiSCN, LiCF3SO3, LiAsF6, LiClO4, lower aliphatic lithium carboxylates, LiCl, LiBR and LiI. The lithium salts can be used alone or two or more of them can be used in combination.

[0133] Examples of sodium salts and potassium salts include those obtained by replacing lithium in the lithium salts above with sodium or potassium.

[0134] The state of the anion in the polymer electrolyte, that is, A and B, can be confirmed by analysis using known techniques, for example LC / MS, NMR and GPC. Liquid electrolyte and electrolyte solution

[0135] The polymer electrolyte may contain a liquid electrolyte or an electrolyte solution, provided that the effects of the present disclosure are not impaired and safety in the high-temperature range is not compromised. Examples include an ionic liquid and a non-aqueous electrolyte solution.

[0136] Specific examples of ionic liquids include the combinations of the following cations and anions.

[0137] The cation is, for example, at least one selected from the group consisting of quaternary ammonium, imidazolium, pyridinium, pyrrolidinium and piperidinium.

[0138] The anion is, for example, 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 fluoroalkylmethanida anion, a fluoroborate anion, a fluorophosphate anion, a dicyanamide anion, a thiocyanate anion, a bis(oxalato)borate anion, a perchlorate anion and derivatives thereof.

[0139] A non-aqueous electrolyte solution is, for example, a liquid in which approximately 1 mole of a lithium salt is dissolved in a non-aqueous solvent. Examples of non-aqueous solvents include ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate. Examples of lithium salts include LiPF6, LiBF4, and LiClO4.

[0140] The ionic conductivity can be improved if the polymer electrolyte contains a liquid electrolyte, but to avoid a reduction 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, based on 100 parts by mass of the polymer contained in the polymer electrolyte.

[0141] If required, the polymer electrolyte can contain non-conductive fillers such as silicon dioxide, quartz powder, titanium dioxide, zinc oxide, and calcium carbonate. When these non-conductive fillers are added to an electrolyte-forming coating material, they act as film-forming aids when the coating material is applied during the electrolyte layer formation step. The non-conductive filler content is preferably 0.1 to 10 parts by mass, based on 100 parts by mass of the electrolyte-forming polymer.

[0142] Additionally, the polymer electrolyte can contain a conductive filler if required, provided that the effects of the present disclosure are not impaired. Conductive fine particles such as carbon black, zinc oxide, tin oxide, and titanium dioxide can be used as the conductive filler. In particular, if the polymer electrolyte is used as the active material binder of the positive or negative electrode, the internal resistance of the secondary battery can be reduced if the polymer electrolyte contains a conductive filler. The content of the conductive filler is preferably 0.5 to 5 parts by mass, based on 100 parts by mass of the polymer contained in the polymer electrolyte.

[0143] The polymer electrolyte is preferably a hardened product of an electrolyte solution.

[0144] The electrolyte solution can, for example, be a mixture of 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 ▪ At least one selected from the group consisting of compounds that have an unsaturated reactive functional group, an anionic functional group, a fluorinated sulfonylimide group or a perfluoroalkylsulfonylimide group, and a cation

[0145] If required, the electrolyte solution can contain a known polymerization initiator. Examples of polymerization initiators include photopolymerization initiators. Additionally, known organic solvents such as methyl ethyl ketone can be used. Method for forming a polymer electrolyte layer

[0146] The process for forming a polymer electrolyte layer is not particularly limited. For example, the polymer electrolyte materials mentioned above are mixed using a known method to obtain an electrolyte solution for forming a polymer electrolyte layer. The electrolyte solution is applied by a known deposition method, such as bar coating, spin coating, or roller coating, and the polymer material contained in the electrolyte solution is then polymerized by a known technique, such as UV irradiation, to form a polymer electrolyte layer. The polymer electrolyte layer can be formed at a desired position, for example, on the positive or negative electrode.

[0147] The thickness of the polymer electrolyte layer as bulk electrolyte is preferably 5.0 µm to 100.0 µm. Examples

[0148] Specific examples and comparisons according to the present disclosure are described below. However, the present disclosure is not limited to the following examples and comparisons.

[0149] First, polyether acrylates were synthesized that formed the structures represented by formula (1) and formula (2). Synthesis examples for polyether monoacrylates that can form the structure represented by formula (1) are shown. Synthesis of polyether monoacrylate Polyether monoacrylate A-1

[0150] 15.5 parts by mass of 1-hexanol (commercially available from Tokyo Chemical Industry Co., Ltd.) and 2 parts by mass of potassium hydroxide (commercially available from Kojundo Chemical Laboratory Co., Ltd.) were placed in an autoclave, stirred at 120 °C under reduced pressure, dissolved, and dehydrated. The pressure in the system was then reduced to -0.1 MPa at 100 °C, and 1041 parts by mass of a gas mixture of ethylene oxide / propylene oxide in a molar ratio of 8:2 were continuously added for 260 minutes while maintaining the pressure in the vessel at approximately 0.5 MPa. While maintaining the temperature at 100 °C, the reaction was carried out for 180 minutes until the pressure in the vessel reached 0.2 MPa or less. The temperature was then increased to 130 °C over 30 minutes with stirring until the pressure change in the vessel reached 0.01 MPa / 30 minutes.Twenty parts by mass of pure water were added to the resulting polymer, and the mixture was stirred at 90 °C for 30 minutes. Then, 50 g of the alkaline adsorbent Kyowaad 600 (commercially available from Kyowa Chemical Industry Co., Ltd.) were added, and the mixture was stirred for another 30 minutes. Next, the alkaline adsorbent was removed by filtration, and the mixture was dried under reduced pressure at 130 °C to obtain a polyether monool with a manganese content of 6,000.

[0151] Next, 100 parts by mass of the obtained polyether monool, 1.26 parts by mass of acrylic acid (commercially available from Nippon Shokubai Co., Ltd.), 2.02 parts by mass of paratoluenesulfonic acid (commercially available from Tokyo Chemical Industry Co., Ltd.), 0.08 parts by mass of hydroquinone (commercially available from Tokyo Chemical Industry Co., Ltd.), and 250 mL of toluene were placed in a Dean-Stark reaction apparatus that included a stirring device. The mixture was heated and stirred at 115 °C and allowed to react for 5 hours, with the water produced during the reaction being removed from the system.

[0152] The temperature of the reaction solution was then lowered to room temperature, washed twice with 120 g of a 5% aqueous sodium hydroxide solution, and additionally washed three times with 120 g of pure water. After washing, the organic phase was separated from the reaction solution, and the solvent was distilled off under reduced pressure to obtain polyether monoacrylate A-1. Polyether monoacrylate A-2

[0153] 18.6 parts by mass of 1-hexanol (commercially available from Tokyo Chemical Industry Co., Ltd.) and 2 parts by mass of potassium hydroxide (commercially available from Kojundo Chemical Laboratory Co., Ltd.) were placed in an autoclave, stirred at 120 °C under reduced pressure, dissolved, and dehydrated. The pressure in the system was then reduced to -0.1 MPa at 100 °C, and 976 parts by mass of a gas mixture of ethylene oxide / propylene oxide in a molar ratio of 95:5 were continuously added for 240 minutes while maintaining the pressure in the vessel at approximately 0.5 MPa. While maintaining the temperature at 100 °C, the reaction was carried out for 180 minutes until the pressure in the vessel reached 0.2 MPa or less. The temperature was then increased to 130 °C over 30 minutes with stirring until the pressure change in the vessel reached 0.01 MPa / 30 minutes.Twenty parts by mass of pure water were added to the resulting polymer, and the mixture was stirred at 90 °C for 30 minutes. Then, 50 g of the alkaline adsorbent Kyowaad 600 (commercially available from Kyowa Chemical Industry Co., Ltd.) were added, and the mixture was stirred for another 30 minutes. Next, the alkaline adsorbent was removed by filtration, and the mixture was dried under reduced pressure at 130 °C to obtain a polyether monoal with a manganese content of 5,000.

[0154] Next, 100 parts by mass of the obtained polyether monool, 1.51 parts by mass of acrylic acid (commercially available from Nippon Shokubai Co., Ltd.), 2.42 parts by mass of paratoluenesulfonic acid (commercially available from Tokyo Chemical Industry Co., Ltd.), 0.08 parts by mass of hydroquinone (commercially available from Tokyo Chemical Industry Co., Ltd.), and 250 mL of toluene were placed in a Dean-Stark reaction apparatus that included a stirring device. The mixture was heated and stirred at 115 °C and allowed to react for 5 hours, with the water produced during the reaction being removed from the system.

[0155] The temperature of the reaction solution was then lowered to room temperature, washed twice with 120 g of a 5% aqueous sodium hydroxide solution, and additionally washed three times with 120 g of pure water. After washing, the organic phase was separated from the reaction solution, and the solvent was distilled off under reduced pressure to obtain polyether monoacrylate A-2. Polyether monoacrylate A-3

[0156] Polyether monoacrylate A-3 was obtained in the same way as polyether monoacrylate A-2, except that the molar ratio of the ethylene oxide / propylene oxide gas mixture was changed to 8:2. Polyether monoacrylate A-4

[0157] 33.7 parts by mass of 1-butanol (commercially available from Tokyo Chemical Industry Co., Ltd.) and 2 parts by mass of potassium hydroxide (commercially available from Kojundo Chemical Laboratory Co., Ltd.) were placed in an autoclave, stirred at 120 °C under reduced pressure, dissolved, and dehydrated. The pressure in the system was then reduced to -0.1 MPa at 100 °C, and 984 parts by mass of a gas mixture of ethylene oxide / propylene oxide in a molar ratio of 8:2 were continuously added for 240 minutes while maintaining the pressure in the vessel at approximately 0.5 MPa. While maintaining the temperature at 100 °C, the reaction was carried out for 150 minutes until the pressure in the vessel reached 0.2 MPa or less. The temperature was then increased to 130 °C over 30 minutes with stirring until the pressure change in the vessel reached 0.01 MPa / 30 minutes.Twenty parts by mass of pure water were added to the resulting polymer, and the mixture was stirred at 90 °C for 30 minutes. Then, 50 g of the alkaline adsorbent Kyowaad 600 (commercially available from Kyowa Chemical Industry Co., Ltd.) were added, and the mixture was stirred for another 30 minutes. Next, the alkaline adsorbent was removed by filtration, and the mixture was dried under reduced pressure at 130 °C to obtain a polyether monoal with a manganese content of 2,000.

[0158] Next, 100 parts by mass of the obtained polyether monool, 3.78 parts by mass of acrylic acid (commercially available from Nippon Shokubai Co., Ltd.), 6.05 parts by mass of paratoluenesulfonic acid (commercially available from Tokyo Chemical Industry Co., Ltd.), 0.11 parts by mass of hydroquinone (commercially available from Tokyo Chemical Industry Co., Ltd.), and 250 mL of toluene were placed in a Dean-Stark reaction apparatus that included a stirring device. The mixture was heated and stirred at 115 °C and allowed to react for 6 hours, with the water produced during the reaction being removed from the system.

[0159] The temperature of the reaction solution was then lowered to room temperature, washed twice with 120 g of a 5% aqueous sodium hydroxide solution, and additionally washed three times with 120 g of pure water. After washing, the organic phase was separated from the reaction solution, and the solvent was distilled off under reduced pressure to obtain polyether monoacrylate A-4. Polyether monoacrylate A-5

[0160] 67.4 parts by mass of 1-butanol (commercially available from Tokyo Chemical Industry Co., Ltd.) and 2 parts by mass of potassium hydroxide (commercially available from Kojundo Chemical Laboratory Co., Ltd.) were placed in an autoclave, stirred at 120 °C under reduced pressure, dissolved, and dehydrated. The pressure in the system was then reduced to -0.1 MPa at 100 °C, and 946 parts by mass of a gas mixture of ethylene oxide / propylene oxide in a molar ratio of 8:2 were continuously added for 240 minutes while maintaining the pressure in the vessel at approximately 0.5 MPa. While maintaining the temperature at 100 °C, the reaction was carried out for 130 minutes until the pressure in the vessel reached 0.2 MPa or less. The temperature was then increased to 130 °C over 30 minutes with stirring until the pressure change in the vessel reached 0.01 MPa / 30 minutes.Twenty parts by mass of pure water were added to the resulting polymer, and the mixture was stirred at 90 °C for 30 minutes. Then, 50 g of the alkali adsorbent Kyowaad 600 (commercially available from Kyowa Chemical Industry Co., Ltd.) were added, and the mixture was 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 monoal with a manganese content of 1000.

[0161] Next, 100 parts by mass of the obtained polyether monool, 7.56 parts by mass of acrylic acid (commercially available from Nippon Shokubai Co., Ltd.), 12.1 parts by mass of paratoluenesulfonic acid (commercially available from Tokyo Chemical Industry Co., Ltd.), 0.11 parts by mass of hydroquinone (commercially available from Tokyo Chemical Industry Co., Ltd.), and 250 mL of toluene were placed in a Dean-Stark reaction apparatus containing a stirrer. The mixture was heated and stirred at 115 °C and allowed to react for 6 hours, with the removal of any water produced during the reaction from the system.

[0162] The temperature of the reaction solution was then lowered to room temperature, washed twice with 120 g of a 5% aqueous sodium hydroxide solution, and additionally washed three times with 120 g of pure water. After washing, the organic phase was separated from the reaction solution, and the solvent was distilled off under reduced pressure to obtain polyether monoacrylate A-5. Polyether monoacrylate A-6

[0163] 169 parts by mass of 1-butanol (commercially available from Tokyo Chemical Industry Co., Ltd.) and 5 parts by mass of potassium hydroxide (commercially available from Kojundo Chemical Laboratory Co., Ltd.) were placed in an autoclave, stirred at 120 °C under reduced pressure, dissolved, and dehydrated. The pressure in the system was then reduced to -0.1 MPa at 100 °C, and 937 parts by mass of a gas mixture of ethylene oxide / propylene oxide in a molar ratio of 8:2 were continuously added for 240 minutes while maintaining the pressure in the vessel at approximately 0.5 MPa. While maintaining the temperature at 100 °C, the reaction was carried out for 120 minutes until the pressure in the vessel reached 0.2 MPa or less. The temperature was then increased to 130 °C over 30 minutes with stirring until the pressure change in the vessel reached 0.01 MPa / 30 minutes.Twenty parts by mass of pure water were added to the resulting polymer, and the mixture was stirred at 90 °C for 30 minutes. Then, 50 g of the alkali adsorbent Kyowaad 600 (commercially available from Kyowa Chemical Industry Co., Ltd.) were added, and the mixture was 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 monoal with a manganese content of 400.

[0164] Next, 100 parts by mass of the obtained polyether monool, 18.9 parts by mass of acrylic acid (commercially available from Nippon Shokubai Co., Ltd.), 24.2 parts by mass of paratoluenesulfonic acid (commercially available from Tokyo Chemical Industry Co., Ltd.), 0.11 parts by mass of hydroquinone (commercially available from Tokyo Chemical Industry Co., Ltd.), and 250 mL of toluene were placed in a Dean-Stark reaction apparatus containing a stirrer. The mixture was heated and stirred at 115 °C and allowed to react for 6 hours, with the removal of any water produced during the reaction from the system.

[0165] The temperature of the reaction solution was then lowered to room temperature, washed twice with 120 g of a 5% aqueous sodium hydroxide solution, and additionally washed three times with 120 g of pure water. After washing, the organic phase was separated from the reaction solution, and the solvent was distilled off under reduced pressure to obtain polyether monoacrylate A-6. Polyether monoacrylate A-7

[0166] Polyether monoacrylate A-7 was obtained in the same way as polyether monoacrylate A-5, except that the molar ratio of the ethylene oxide / propylene oxide gas mixture was changed to 5:5. Polyether monomethacrylate A-8

[0167] 112 parts by mass of 1-butanol (commercially available from Tokyo Chemical Industry Co., Ltd.) and 5 parts by mass of potassium hydroxide (commercially available from Kojundo Chemical Laboratory Co., Ltd.) were placed in an autoclave, stirred at 120 °C under reduced pressure, dissolved, and dehydrated. The pressure in the system was then reduced to -0.1 MPa at 100 °C, and 937 parts by mass of a 5:5 molar ethylene oxide / propylene oxide gas mixture were continuously added for 240 minutes while maintaining a pressure in the vessel at approximately 0.5 MPa. While maintaining the temperature at 100 °C, the reaction was carried out for 120 minutes until the pressure in the vessel reached 0.2 MPa or less. The temperature was then increased to 130 °C over 30 minutes with stirring until the pressure change in the vessel reached 0.01 MPa / 30 minutes.Twenty parts by mass of pure water were added to the resulting polymer, and the mixture was stirred at 90 °C for 30 minutes. Then, 50 g of the alkali adsorbent Kyowaad 600 (commercially available from Kyowa Chemical Industry Co., Ltd.) were added, and the mixture was 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 monoal with a manganese content of 600.

[0168] Next, 100 parts by mass of the obtained polyether monool, 15.0 parts by mass of methacrylic acid (commercially available from Mitsubishi Gas Chemical Company, Inc.), 20.2 parts by mass of paratoluenesulfonic acid (commercially available from Tokyo Chemical Industry Co., Ltd.), 0.11 parts by mass of hydroquinone (commercially available from Tokyo Chemical Industry Co., Ltd.), and 250 mL of toluene were placed in a Dean-Stark reaction apparatus containing a stirrer. The mixture was heated and stirred at 115 °C and allowed to react for 6 hours, with the removal of any water produced during the reaction from the system.

[0169] The temperature of the reaction solution was then lowered to room temperature, washed twice with 120 g of a 5% aqueous sodium hydroxide solution, and additionally washed three times with 120 g of pure water. After washing, the organic phase was separated from the reaction solution, and the solvent was distilled off under reduced pressure to obtain polyether monomethacrylate A-8. Polyether monomethacrylate A-9

[0170] A polyether monoalcohol with a Mn of 400 was obtained in the same way as the polyether monoacrylate A-6, except that the molar ratio of the ethylene oxide / propylene oxide gas mixture was changed to 5:5.

[0171] Next, 100 parts by mass of the obtained polyether monool, 22.6 parts by mass of methacrylic acid (commercially available from Mitsubishi Gas Chemical Company, Inc.), 24.2 parts by mass of paratoluenesulfonic acid (commercially available from Tokyo Chemical Industry Co., Ltd.), 0.11 parts by mass of hydroquinone (commercially available from Tokyo Chemical Industry Co., Ltd.), and 250 mL of toluene were placed in a Dean-Stark reaction apparatus containing a stirrer. The mixture was heated and stirred at 115 °C and allowed to react for 6 hours, with the water produced during the reaction being removed from the system.

[0172] The temperature of the reaction solution was then lowered to room temperature, washed twice with 120 g of a 5% aqueous sodium hydroxide solution, and additionally washed three times with 120 g of pure water. After washing, the organic phase was separated from the reaction solution, and the solvent was distilled off under reduced pressure to obtain polyether monomethacrylate A-9.

[0173] The polyethermono(meth)acrylates obtained are shown in Table 1.

[0174] Next, examples of the synthesis of polyether diacrylates that can form the structure represented by formula (2) are shown. Synthesis of polyether diacrylate. Polyether diacrylate B-1

[0175] 13.7 parts by mass of 1,4-butanediol (commercially available from Tokyo Chemical Industry Co., Ltd.) and 2 parts by mass of potassium hydroxide (commercially available from Kojundo Chemical Laboratory Co., Ltd.) were placed in an autoclave, stirred at 120 °C under reduced pressure, dissolved, and dehydrated. Next, the pressure in 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 in a molar ratio of 8:2 were continuously added for 280 minutes while maintaining the pressure in the vessel at approximately 0.5 MPa. While maintaining the temperature at 100 °C, the reaction was carried out for 170 minutes until the pressure in the vessel reached 0.2 MPa or less. Then, the temperature was increased to 130 °C over 30 minutes, with stirring, until the pressure change in the vessel reached 0.01 MPa / 30 minutes.Twenty parts by mass of pure water were added to the resulting polymer, and the mixture was stirred at 90 °C for 30 minutes. Then, 50 g of the alkaline adsorbent Kyowaad 600 (commercially available from Kyowa Chemical Industry Co., Ltd.) was added, and the mixture was stirred for another 30 minutes. Next, the alkaline adsorbent was removed by filtration, and the mixture was dried under reduced pressure at 130 °C to obtain a polyetherdiol with a manganese content of 6,000.

[0176] Next, 100 parts by mass of the obtained polyetherdiol, 2.52 parts by mass of acrylic acid (commercially available from Nippon Shokubai Co., Ltd.), 2.02 parts by mass of paratoluenesulfonic acid (commercially available from Tokyo Chemical Industry Co., Ltd.), 0.08 parts by mass of hydroquinone (commercially available from Tokyo Chemical Industry Co., Ltd.), and 250 mL of toluene were placed in a Dean-Stark reaction apparatus containing a stirrer. The mixture was heated and stirred at 115 °C and allowed to react for 6 hours, with the removal of any water produced during the reaction from the system.

[0177] The temperature of the reaction solution was then lowered to room temperature, washed twice with 120 g of a 5% aqueous sodium hydroxide solution, and additionally washed three times with 120 g of pure water. After washing, the organic phase was separated from the reaction solution, and the solvent was distilled off under reduced pressure to obtain polyether diacrylate B-1. Polyether diacrylate B-2

[0178] A polyetherdiol with a Mn of 5,000 was obtained in the same way as polyether diacrylate B-1, except that the amount of 1,4-butanediol (commercially available from Tokyo Chemical Industry Co., Ltd.) was changed to 16.4 parts by mass.

[0179] Next, 100 parts by mass of the obtained polyetherdiol, 3.02 parts by mass of acrylic acid (commercially available from Nippon Shokubai Co., Ltd.), 2.42 parts by mass of paratoluenesulfonic acid (commercially available from Tokyo Chemical Industry Co., Ltd.), 0.08 parts by mass of hydroquinone (commercially available from Tokyo Chemical Industry Co., Ltd.), and 250 mL of toluene were placed in a Dean-Stark reaction apparatus that included a stirring device. The mixture was heated and stirred at 115 °C and allowed to react for 5 hours, with the water produced during the reaction being removed from the system.

[0180] The temperature of the reaction solution was then lowered to room temperature, washed twice with 120 g of a 5% aqueous sodium hydroxide solution, and additionally washed three times with 120 g of pure water. After washing, the organic phase was separated from the reaction solution, and the solvent was distilled off under reduced pressure to obtain polyether diacrylate B-2. Polyether diacrylate B-3

[0181] 41.0 parts by mass of 1,4-butanediol (commercially available from Tokyo Chemical Industry Co., Ltd.) and 2 parts by mass of potassium hydroxide (commercially available from Kojundo Chemical Laboratory Co., Ltd.) were placed in an autoclave and stirred, dissolved, and dehydrated at 120 °C under reduced pressure. Next, the pressure in 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 in a molar ratio of 9:1 were continuously added for 220 minutes while maintaining the pressure in the vessel at approximately 0.5 MPa. While maintaining the temperature at 100 °C, the reaction was carried out for 150 minutes until the pressure in the vessel reached 0.2 MPa or less. Then, the temperature was increased to 130 °C over 30 minutes, with stirring, until the pressure change in the vessel reached 0.01 MPa / 30 minutes.Twenty parts by mass of pure water were added to the resulting polymer, and the mixture was stirred at 90 °C for 30 minutes. Then, 50 g of the alkaline adsorbent Kyowaad 600 (commercially available from Kyowa Chemical Industry Co., Ltd.) were added, and the mixture was stirred for another 30 minutes. Next, the alkaline adsorbent was removed by filtration, and the mixture was dried under reduced pressure at 130 °C to obtain a polyetherdiol with a manganese content of 2,000.

[0182] Next, 100 parts by mass of the obtained polyetherdiol, 7.56 parts by mass of acrylic acid (commercially available from Nippon Shokubai Co., Ltd.), 6.05 parts by mass of paratoluenesulfonic acid (commercially available from Tokyo Chemical Industry Co., Ltd.), 0.11 parts by mass of hydroquinone (commercially available from Tokyo Chemical Industry Co., Ltd.), and 250 mL of toluene were placed in a Dean-Stark reaction apparatus that included a stirring device. The mixture was heated and stirred at 115 °C and allowed to react for 5 hours, with the water produced during the reaction being removed from the system.

[0183] The temperature of the reaction solution was then lowered to room temperature, washed twice with 120 g of a 5% aqueous sodium hydroxide solution, and additionally washed three times with 120 g of pure water. After washing, the organic phase was separated from the reaction solution, and the solvent was distilled off under reduced pressure to obtain polyether diacrylate B-3. Polyether diacrylate B-4

[0184] 205 parts by mass of 1,4-butanediol (commercially available from Tokyo Chemical Industry Co., Ltd.) and 2 parts by mass of potassium hydroxide (commercially available from Kojundo Chemical Laboratory Co., Ltd.) were placed in an autoclave, stirred at 120 °C under reduced pressure, dissolved, and dehydrated. Next, the pressure in 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 in a molar ratio of 9:1 were continuously added for 210 minutes while maintaining the pressure in the vessel at approximately 0.5 MPa. While maintaining the temperature at 100 °C, the reaction was carried out for 110 minutes until the pressure in the vessel reached 0.2 MPa or less. Then, the temperature was increased to 130 °C over 30 minutes with stirring until the pressure change in the vessel reached 0.01 MPa / 30 minutes.Twenty parts by mass of pure water were added to the resulting polymer, and the mixture was stirred at 90 °C for 30 minutes. Then, 50 g of the alkali adsorbent Kyowaad 600 (commercially available from Kyowa Chemical Industry Co., Ltd.) were 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 polyetherdiol with a manganese content of 400.

[0185] Next, 100 parts by mass of the obtained polyetherdiol, 37.8 parts by mass of acrylic acid (commercially available from Nippon Shokubai Co., Ltd.), 24.2 parts by mass of paratoluenesulfonic acid (commercially available from Tokyo Chemical Industry Co., Ltd.), 0.11 parts by mass of hydroquinone (commercially available from Tokyo Chemical Industry Co., Ltd.), and 250 mL of toluene were placed in a Dean-Stark reaction apparatus that included a stirring device. The mixture was heated and stirred at 115 °C and allowed to react for 6 hours, with the water produced during the reaction being removed from the system.

[0186] The temperature of the reaction solution was then lowered to room temperature, washed twice with 120 g of a 5% aqueous sodium hydroxide solution, and additionally washed three times with 120 g of pure water. After washing, the organic phase was separated from the reaction solution, and the solvent was distilled off under reduced pressure to obtain polyether diacrylate B-4. Polyether diacrylate B-5

[0187] Polyether diacrylate B-5 was obtained in the same way as polyether diacrylate B-2, except that the molar ratio of the ethylene oxide / propylene oxide gas mixture was changed to 9:1. Polyether dimethacrylate B-6

[0188] A polyetherdiol with a Mn of 1,000 was obtained in the same way as polyether diacrylate B-3, except that 82.0 parts by mass of 1,4-butanediol (commercially available from Tokyo Chemical Industry Co., Ltd.) were used and the molar ratio of the ethylene oxide / propylene oxide gas mixture was changed to 5:5.

[0189] Next, 100 parts by mass of the obtained polyetherdiol, 18.1 parts by mass of methacrylic acid (commercially available from Mitsubishi Gas Chemical Company, Inc.), 12.1 parts by mass of paratoluenesulfonic acid (commercially available from Tokyo Chemical Industry Co., Ltd.), 0.11 parts by mass of hydroquinone (commercially available from Tokyo Chemical Industry Co., Ltd.), and 250 mL of toluene were placed in a Dean-Stark reaction apparatus containing a stirrer. The mixture was heated and stirred at 115 °C and allowed to react for 6 hours, with the water produced during the reaction removed from the system. The temperature of the reaction solution was then lowered to room temperature, washed twice with 120 g of a 5% aqueous sodium hydroxide solution, and additionally washed 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 a polyether diacrylate B-6.

[0190] The polyether di(meth)acrylates obtained are listed in Table 2. [Table 1] Molecular structure Polyether composition ratio Polyether Molecular weight Number of carbon atoms Average number of added moles EO PO Starting material R2 R3 m1 n1 A-1 Monoacrylate 80 20 1-Hexanol 6000 2 or 3 6 108 20 A-2 95 5 5000 2 or 3 6 106 4 A-3 80 20 5000 2 or 3 6 89 17 A-4 80 20 1-Butanol 2000 2 or 3 4 35 7 A-5 80 20 1000 2 or 3 4 17 3 A-6 80 20 400 2 or 3 4 6 1 A-7 50 50 1000 2 or 3 4 11 8 A-8 Mono(meth)-acrylate 50 50 600 2 or 3 4 6 5 A-9 50 50 400 2 or 3 4 4 3

[0191] The polyether composition ratio indicates the molar ratio. EO stands for ethylene oxide and PO for propylene oxide. [Table 2] Molecular structure Polyether composition ratio Polyether Molecular weight Number of carbon atoms Average number of added moles EO PO Starting material R5 R6 m2 n2 B-1 Diacrylate 80 20 1,4-Butanediol 6000 2 or 3 2 or 3 109 21 B-2 80 20 5000 2 or 3 2 or 3 91 17 B-3 90 10 2000 2 or 3 2 or 3 41 3 B-4 90 10 400 2 or 3 2 or 3 8 1 B-5 90 10 5000 2 or 3 2 or 3 102 9 B-6 Dimethacrylate 50 50 1000 2 or 3 2 or 3 11 9

[0192] The polyether composition ratio indicates the molar ratio. EO stands for ethylene oxide and PO for propylene oxide. Synthesis of reactive ionic compounds Synthesis of the ionic compound C-1

[0193] 15.0 g (0.06 mol) of 3-sulfopropyl methacrylate potassium salt (commercially available from Tokyo Chemical Industry Co., Ltd.) were suspended in 100 mL of THF, and 0.5 mL of N,N-dimethylformamide and 20 mL (0.28 mol) of thionyl chloride were then added. The mixture was stirred for 3 hours. The mixture was concentrated under reduced pressure, the residue was dissolved in dichloromethane, then washed with 50 mL of pure water and 50 mL of sodium chloride solution, and then the mixture was concentrated again under reduced pressure to obtain a pale yellow liquid.

[0194] The resulting pale yellow liquid was added to a solution obtained by dissolving 9.20 g (0.06 mol) of trifluoromethanesulfonamide (commercially available from Tokyo Chemical Industry Co., Ltd.) and 27.3 mL (0.20 mol) of triethylamine (commercially available from Kishida Chemical Co., Ltd.) in 50 mL of tetrahydrofuran. The mixture was stirred for 2 hours, and 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, 1.43 g (0.18 mol) of lithium hydride (commercially available from FUJIFILM Wako Pure Chemical Corporation) was added, and the mixture was stirred overnight.Unreacted lithium hydride was filtered through Celite and the filtrate was then dried under reduced pressure to obtain the ionic compound C-1. Synthesis of the ionic compound C-2

[0195] Ionic compound C-2 was obtained in the same way as ionic compound C-1, except that the raw material was changed to 15.9 g (0.06 mol) of 3-sulfopropyl acrylate potassium salt (commercially available from Tokyo Chemical Industry Co., Ltd.). Synthesis of the ionic compound C-3

[0196] 7.78 g (0.07 mol) of hydroxymethanesulfonate (commercially available from Atomax Chemicals Product) were dissolved in 50 mL of THF, 5.17 g (0.06 mol) of methacrylic acid (commercially available from Kishida Chemical Co., Ltd.) and molecular sieves were added, and the mixture was stirred for 3 hours at 80 °C. The filtrate obtained by Celite was dried under reduced pressure and then dissolved again in 50 mL of THF, 2.41 g (0.06 mol) of potassium hydride (commercially available from Merck) were added, and the mixture was stirred for 2 hours at room temperature. The white solid obtained after drying under reduced pressure was used as a raw material, and ionic compound C-3 was obtained in the same manner as ionic compound C-1. Synthesis of the ionic compound C-4

[0197] 12.9 g of 1-heptanesulfonyl chloride, 7-hydroxy (commercially available from Hong Kong Chemhere Product) and 6.07 g (0.06 mol) of triethylamine (commercially available from Kishida Chemical Co., Ltd.) were added to 80 mL of dichloromethane, and the mixture was 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 (commercially available from Merck) were dissolved in 50 mL of ethanol, the oily liquid obtained above, and 0.022 g (0.20 mmol) of hydroquinone (commercially available from Kanto Chemical Co., Inc.) were added, and the mixture was stirred for 5 hours at 70 °C. The pale yellow solid obtained after drying under reduced pressure was used as raw material, and an ionic compound C-4 was obtained in the same way as the ionic compound C-2. Synthesis of the ionic compound C-5

[0198] An ionic compound C-5 was obtained in the same way as the ionic compound C-2, except that the reagent trifluoromethanesulfonamide (commercially available from Tokyo Chemical Industry Co., Ltd.) was replaced by 5.94 g (0.06 mol) sulfamoyl fluoride (commercially available from Atomax Chemicals Product). Synthesis of the ionic compound C-6

[0199] An ionic compound C-6 was obtained in the same way as the ionic compound C-1, except that the reagent trifluoromethanesulfonamide (commercially available from Tokyo Chemical Industry Co., Ltd.) was replaced by 18.0 g (0.06 mol) of nonafluorobutane-1-sulfonamide (commercially available from Enamine Ltd.). Synthesis of the ionic compound C-7

[0200] An ionic compound C-7 was obtained in the same way as the ionic compound C-5, except that lithium hydride was replaced as the reagent by 4.32 g (0.18 mol) sodium hydride (commercially available from Tokyo Chemical Industry Co., Ltd.). Synthesis of the ionic compound C-8

[0201] An ionic compound C-8 was obtained in the same way as the ionic compound C-6, except that lithium hydride was replaced as the reagent by 7.22 g (0.18 mol) of potassium hydride (commercially available from Merck).

[0202] The chemical structures of the obtained reactive ionic compounds are shown in formulas C-1 to C-8. Preparation of an electrolyte solution from polymer electrolyte Example 1

[0203] The following materials were mixed and stirred as polymer electrolyte materials. ▪ Polyether monoacrylate NK ester M-230G (commercially available from 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 ▪ Initiator Omnirad184 (commercially available from IGM RESINS BV): 2.0 mass parts

[0204] Next, methyl ethyl ketone (hereinafter referred to as "MEK") was added so that the total solids content was 60 wt%, and the mixture was then blended by motor stirring to provide an electrolyte solution. Measurement of the volume swelling ratio using the MEK immersion method

[0205] Test specimens for determining the volume swelling ratio by the MEK immersion method were prepared using electrolyte solutions of the following examples. A predetermined amount of a surface-film-forming dispersion solution of each example was placed in an aluminum mold whose surface was coated with a fluorinated resin, resulting in a film thickness of 200 µm. The sample was then placed on a sunflower-type stand and dried until the viscosity increased to the point where the film surface no longer flowed, and then placed on a horizontal table and dried for 2 hours at 60 °C.

[0206] Next, UV light was irradiated onto the film surface using a high-pressure mercury UV irradiation device (product name: Handy 1000, commercially available from Marionetwork) in an atmospheric environment, resulting in a cumulative light dose of 5,000 mJ / cm². 2was, and the polymer electrolyte was cross-linked and hardened.

[0207] After curing, the sample was left for 24 hours in an environment of 23 °C and 40% relative humidity, and the electrolyte film was removed from the aluminum mold to produce a foil with a film thickness of 200 µm. The resulting polymer electrolyte foil was cut into 50 mm × 50 mm pieces and left for 24 hours in an environment of 23 °C and 40% relative humidity to form a test piece.

[0208] First, the initial weight in air (W1) and the initial weight in water (W2) were measured at an ambient temperature of 23 °C and 40% relative humidity. Next, after measuring the initial weight, the sample was immersed in MEK for 48 hours at 23 °C. Immediately after removing the sample from the MEK, the MEK was wiped from the surface with a non-woven fabric, the sample 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)×100 W1: Initial weight in air W2: Initial weight in water W3: Weight after immersion in air W4: Weight after immersion in water Measurement of ionic conductivity at normal temperature (25 °C)

[0209] The electrolyte solution obtained in Example 1 was applied to a 100 µm thick aluminum plate using a bar coater and dried for 30 minutes at 60 °C. Next, UV light was irradiated onto the film surface using a high-pressure mercury UV irradiator (product name: Handy 1000, commercially available from Marionetwork) to achieve a cumulative light dose of 5,000 mJ / cm². 2 The polymer electrolyte film was cross-linked and cured according to Example 1. The film thickness after curing was 60 µm.

[0210] The resulting polymer electrolyte film, along with the aluminum substrate, was die-cut into 50 mm diameter pieces and vacuum-dried at 80 °C for 48 hours. The polymer electrolyte film was then placed in an argon-purged glovebox (at a temperature of 25 °C and a dew point of -70 °C). The AC impedance between the electrodes was measured using an E4990A impedance analyzer (commercially available from KEYSIGHT) at an applied voltage of 10 mV over a frequency range of 100 MHz to 1 Hz. The bulk resistance value R B (Ω) was obtained from the intersection of the real impedance of the obtained Cole-Cole plot, and the ionic conductivity was determined by the following formula. σ=L / RB×S (σ: ionic conductivity (S·cm) -1 ), L: Sample thickness (cm), S: Sample area (cm²) 2 ))

[0211] Low-temperature (5 °C) ionic conductivity measurement: A polymer electrolyte film was formed on an aluminum plate in the same manner as for the standard-temperature ionic conductivity measurement. The polymer electrolyte layer was then placed in an argon-purged glovebox (at a temperature of 25 °C and a dew point of -70 °C) and installed in an all-solid-state battery evaluation cell (commercially available from Hohsen Corporation).

[0212] The evaluation cell, into which the polymer electrolyte film was installed, was placed in a low-temperature environmental testing machine and left at 5 °C for 1 hour. The low-temperature ionic conductivity was then determined in the same manner as in the measurement described above. Production of a secondary battery 1. Configuration in which the polymer electrolyte of the present disclosure was used as a bulk electrolyte Production of a negative electrode

[0213] A 20 mm × 20 mm lithium foil with a thickness of 60 µm (commercially available from Honjo Metal Co., Ltd.) was laminated to a 20 mm × 30 mm copper foil with a thickness of 20 µm, leaving a 10 mm long unlaminated edge on one side, and press-fit was performed to produce a negative electrode. The total thickness of the produced negative electrode was 70 µm. A nickel-plated copper tab, 5 mm wide, was bonded to the unlaminated end of the negative electrode. Production of a positive electrode

[0214] 100 parts by mass of lithium cobalt oxide (commercially available from FUJIFILM Wako Pure Chemical Corporation), 7 parts by mass of Kureha KF Polymer L#1120 (commercially available from Kureha Corporation) as an active material binder, and 5 parts by mass of Denka Black Li-100 (commercially available from Denka Co., Ltd.) as a conductivity aid were mixed. 40 parts by mass of N-methylpyrrolidone were added, and the mixture was blended and stirred. Next, the resulting slurry was applied to a 15 mm × 25 mm rolled aluminum foil with a thickness of 20 µm, leaving a 10 mm uncoated border on one side. It was dried for 30 minutes at 100 °C and pressed to form a positive electrode. The thickness of the positive electrode was 80 µm.

[0215] In the positive electrode, an aluminum tab with a width of 5 mm was connected to the end that was uncoated on one side. Formation of a polymer electrolyte layer

[0216] The electrolyte solution was applied to the entire surface of the resulting positive electrode coated with the active material using a bar coater, air-dried for 10 minutes at 23 °C, and then dried for 30 minutes at 60 °C. Next, UV light was irradiated onto the film surface using a high-pressure mercury UV irradiator (product name: Handy 1000, commercially available from Marionetwork), resulting in a cumulative light dose of 5,000 mJ / cm². 2 The film was cured, and the curing process was carried out. The film thickness after curing was 60 µm. Production of a secondary battery using a polymer electrolyte as a bulk electrolyte

[0217] The positive electrode coated with the polymer electrolyte was vacuum-dried at 80 °C for 48 hours. The polymer electrolyte layer was then placed in an argon-purged glovebox (at a temperature of 25 °C and a dew point of -70 °C), and a window-frame-shaped polyimide film was applied to cover the outer edge of the positive electrode surface, forming a short-circuit prevention layer. Next, lamination was performed so that the polymer electrolyte layer of the polymer electrolyte-coated positive electrode corresponded to the lithium layer of the negative electrode. The laminate was embedded in the aluminum laminate film and vacuum-packed to obtain a secondary battery according to Example 1. Battery characteristics evaluation, charging rate

[0218] The theoretical capacity was determined based on the total mass of lithium cobalt oxide contained in the positive electrode. The prototype secondary batteries were subjected to a charge and discharge test at 25 °C using a BCS-805 charge and discharge unit (commercially available from BioLogic Co., Ltd.).

[0219] The theoretical capacity was determined based on the total mass of the lithium cobalt oxide contained in the positive electrode, and in the first cycle the battery was subjected to a constant voltage charge for 2 hours at a charging rate of 0.05 C and a cutoff value of 3.9 V. The battery was subjected to a constant voltage discharge for 1 hour with a discharge rate of 0.05 C and a cutoff value of 2.0 V.

[0220] Next, the charging and discharging rates were increased in steps of 0.05 C, the same charging and discharging operations were carried out, and the rate at which charging and discharging operations could be carried out without exceeding the limit was defined as the charging rate. Assessment of strength at high temperatures

[0221] The secondary battery prototypes underwent a shock test using a QC-633 thin-film shock tester (commercially available from Cometech Testing Machines) in an environment of 25°C, with a peak impact diameter of 38.1 mm, a load of 120 g, a height of 150 mm, and a single shock repetition. A battery short-circuit test was then performed using a test device. Five batteries of each type were manufactured, a total of five impact tests were performed, and the number of batteries that short-circuited was counted.

[0222] Next, the impact test machine and the secondary batteries were placed in an environmental test machine set to 60 °C and left there for 2 hours. The same test was then carried out and the number of batteries that short-circuited in the high-temperature test was counted. Assessment of the occurrence of short circuits

[0223] The secondary battery prototypes underwent repeated charge and discharge testing in an environment of 40 °C. Charging was performed at a rate of 0.05 C and a voltage of 4.0 V, and discharging at a rate of 0.05 C and a voltage of 3.0 V. The number of cycles until abnormal voltage behavior occurred during charging and discharging was counted.

[0224] Next, the electrodes were removed from the evaluated batteries and the presence of dendrites on the surface was observed using a VHX-5000 digital microscope (commercially available from Keyence Corporation) with 50x and 500x objective lenses. Examples 2 to 32

[0225] 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 formulation amounts of polyether mono(meth)acrylate, polyether di(meth)acrylate, ionic compounds and supporting electrolytes were changed as shown in Table 3. [Table 3] Polyether mono(meth)-acrylate Polyether di(meth)acrylate or tri(meth)acrylate Reactive ion Supportive electrolyte Nr. Mass parts Nr. Mass parts Nr. Mass parts Nr. Mass parts Example 1 M-230G 50 B-1 50 C-3 5 Li▪TFSI 20 Example 2 A-1 50 14G 50 C-3 5 Li▪TFSI 20 Example 3 A-2 70 B-2 30 C-1 5 Li▪FSI 20 Example 4 AM-130G 70 B-2:: 30 C-1 5 Li▪FSI 20 Example 5 A-3 90 A-1000PER 10 C-1 5 Li▪FSI 20 Example 6 MEMA-4000 90 A-1000PER 10 C-1 5 Li▪FSI 20 Example 7 A-4 90 A-1000PER 10 C-1 5 Li▪FSI 20 Example 8 A-5 90 A-1000PER 10 C-1 5 Li▪FSI 20 Example 9 A-6 90 A-1000PER 10 C-1 5 Li▪FSI 20 Example 10 A-4 90 A-1000PER 10 C-1 5 Li▪TFSI 20 Example 11 A-4 90 A-1000PER 10 C-1 5 Li▪PF6 20 Example 12 A-4 70 B-3 30 C-4 5 Li▪FSI 20 Example 13 AM-230G 70 A-1000PER 30 C-2 5 Li▪TFSI 20 Example 14 A-5 70 A-1000PER 30 C-2 5 Li▪TFSI 20 Example 15 A-7 70 A-1000PER 30 C-2 5 Li▪TFSI 20 Example 16 A-5 95 B-4 5 C-1 5 Li▪TFSI 20 Example 17 A-5 95 B-3 5 C-5 5 Li▪TFSI 20 Example 18 A-5 95 B-5 5 C-6 5 Li▪TFSI 20 Example 19 A-5 95 A-1000 5 C-7 5 Li▪TFSI 20 Example 20 A-5 95 B-6 5 C-8 5 Li▪TFSI 20 Example 21 AM-90G 98 A-400 2 C-6 5 Li▪TFSI 20 Example 22 AM-130G 98 A-600 2 C-6 5 Li▪TFSI 20 Example 23 A-5 98 A-1000 2 C-6 5 Li▪TFSI 20 Example 24 M-450G 98 PEGDA-4000 2 C-6 5 Li▪TFSI 20 Example 25 A-4 95 B-3 5 C-1 5 Li▪TFSI 5 Example 26 A-4 95 B-3 5 C-1 5 Li▪TFSI 10 Example 27 A-4 95 B-3 5 C-1 5 Li▪TFSI 15 Example 28 A-4 95 B-3 5 C-1 5 Li▪TFSI 20 Example 29 A-4 95 B-3 5 C-1 3 Li▪TFSI 20 Example 30 A-4 95 B-3 5 C-1 1 Li▪TFSI 20 Example 31 A-9 98 9G 2 C-3 1 Li▪TFSI 20 Example 32 A-8 98 A-GLY-20E 2 C-3 1 Li▪TFSI 20

[0226] The structures, once the materials used have polymerized, are as follows.

[0227] M-230G (Methoxypolyethylene glycol methacrylate, in formula (1-1), R1: methyl group, R2: ethylene group -(CH2)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)

[0228] A-1000PER (in formula (2-1), R4: hydrogen atom, R5: ethylene group or propylene group, R6: ethylene group or propylene group, m2: 17, n2: 4) A-1000 (Polyethylene glycol #1000 diacrylate, in formula (2-1), R4: hydrogen atom, R5: ethylene group, R6: ethylene group, m2: 23, n2: 0) A-400 (Polyethylene glycol #400 diacrylate, in formula (2-1), R4: hydrogen atom, R5: ethylene group, R6: ethylene group, m2: 9, n2: 0) A-600 (Polyethylene glycol #600-Diacrylate, in formula (2-1), R4: hydrogen atom, R5: ethylene group, R6: ethylene group, m2: 14, n2: 0) A-GLY-20E (ethoxylated glycerol triacrylate, in formula (3-1), R7: hydrogen atom, R8: ethylene group, R9: ethylene group, R10: ethylene group, R11: -CH2(CH-)CH2-, m3: 20 as sum 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 the above materials are commercially available from Shin-Nakamura Chemical Co., Ltd.

[0229] MEMA-4000: (Polyethylene glycol #4000 dimethacrylate (in formula (2-1), R4: methyl group, R5: ethylene group, R6: ethylene group, m2: 90, n2: 0)), commercially available from TOHO Chemical Industry Co., Ltd. PEGDA-4000: (Polyethylene glycol diacrylate, in formula (2-1) R4: hydrogen atom, R5: ethylene group, R6: ethylene group, m2: 90, n2: 0), commercially available from Sun Techno Chemical Co., Ltd. Li▪TFSI is the name for (Lithium bis(trifluoromethanesulfonyl)imide).

[0230] Li▪FSI denotes (Lithium bis(fluorosulfonyl)imide). Li▪PF6 is designated (lithium hexafluorophosphate).

[0231] 2. Configuration in which the polymer electrolyte of the present disclosure was used as the active material binder of the positive electrode. Example 33: Production of the negative electrode

[0232] A 20 mm × 20 mm lithium foil with a thickness of 60 µm (commercially available from Honjo Metal Co., Ltd.) was laminated to a 20 mm × 30 mm copper foil with a thickness of 20 µm, leaving a 10 mm long unlaminated edge on one side, and press-fitted to create a negative electrode. The total thickness of the resulting negative electrode was 70 µm. A 5 mm wide nickel-plated copper tab was bonded to the unlaminated end of the negative electrode. Solid electrolyte

[0233] A 20 mm × 20 mm sheet with a thickness of 0.18 mm LICGC (commercially available from Ohara Inc.) was used. Production of the positive electrode

[0234] 100 parts by mass of lithium cobalt oxide (commercially available from FUJIFILM Wako Pure Chemical Corporation), 18 parts by mass of the electrolyte solution (a solids content of 60%) from Example 1 as the active material binder, and 5 parts by mass of Denka Black Li-100 (commercially available from Denka Co., Ltd.) as a conductivity aid were mixed, 40 parts by mass of N-methylpyrrolidone were added, and the mixture was mixed and stirred. Next, the obtained slurry was applied to a 15 mm × 25 mm rolled aluminum foil with a thickness of 20 µm, leaving a 10 mm long uncoated border on one side, and dried for 30 minutes at 100 °C. Then, using a high-pressure mercury UV irradiation device (product name: Handy 1000, commercially available from Marionetwork), UV light was shone onto the film surface, resulting in a cumulative light dose of 7,000 mJ / cm². 2The electrode was then cured. After curing, a pressing process was carried out to obtain a positive electrode with a thickness of 80 µm. An aluminum tab with a width of 5 mm was connected to the uncoated end of the positive electrode. Production of the secondary battery using the polymer electrolyte as the active material binder of the positive electrode

[0235] A positive electrode, in which the polymer electrolyte was used as the active material binder, was vacuum-dried at 80 °C for 48 hours. The polymer electrolyte film was then placed in an argon-purged glovebox (at a temperature of 25 °C and a dew point of -70 °C), and the positive electrode / solid electrolyte / negative electrode were laminated in that order. The laminate was inserted into the aluminum laminate foil and vacuum-packed to obtain a secondary battery in which the polymer electrolyte of the present disclosure was used as the active material binder of the positive electrode according to Example 33. Examples 34 to 36

[0236] Secondary batteries according to Examples 34 to 36 were manufactured in the same manner as in Example 33, except that the electrolyte solutions (polymer electrolyte) were changed as shown in Table 7. The evaluation results, such as the charging rate, are presented in Table 7. 3. Configuration in which the polymer electrolyte of the present disclosure was used as the bulk electrolyte, active material binder of the positive electrode and active material binder of the negative electrode. Example 37: Fabrication of the negative electrode

[0237] 100 parts by mass of graphite powder (commercially available from FUJIFILM Wako Pure Chemical Corporation), 20 parts by mass of the electrolyte solution (a solids content of 60%) from Example 1 as the active material binder, and 5 parts by mass of Denka Black Li-100 (commercially available from Denka Co., Ltd.) as a conductivity aid were mixed, 80 parts by mass of N-methylpyrrolidone were added, and the mixture was mixed and stirred. Next, the obtained slurry was applied to a 20 mm × 30 mm copper foil with a thickness of 20 µm, leaving a 10 mm long uncoated border on one side, and dried for 30 minutes at 100 °C. Then, using a high-pressure mercury UV irradiation device (product name: Handy 1000, commercially available from Marionetwork), UV light was shone onto the film surface, resulting in a cumulative light dose of 8,000 mJ / cm². 2The material was cured and hardened. After hardening, pressing was performed to obtain a negative electrode with a thickness of 80 µm. At both ends, a portion not coated with the active material of the negative electrode was provided, and a 5 mm wide, nickel-plated copper current tap was bonded to this portion. Production of the positive electrode

[0238] 100 parts by mass of lithium cobalt oxide (commercially available from FUJIFILM Wako Pure Chemical Corporation), 18 parts by mass of the electrolyte solution (a solids content of 60%) from Example 1 as the active material binder, and 5 parts by mass of Denka Black Li-100 (commercially available from Denka Co., Ltd.) as a conductivity aid were mixed. 40 parts by mass of N-methylpyrrolidone were added, and the mixture was blended and stirred. Next, the resulting slurry was applied to a rolled aluminum foil 20 µm thick and dried at 60 °C for 30 minutes. Then, using a high-pressure mercury UV irradiator (product name: Handy 1000, commercially available from Marionetwork), UV light was applied to the film surface, resulting in a cumulative light dose of 7,000 mJ / cm². 2The material was then cured. After curing, pressing was performed to obtain a positive electrode with a thickness of 80 µm. At both ends, a portion uncoated with the active material of the positive electrode was provided, and a 5 mm wide aluminum current tap was attached to this uncoated portion. Formation of a polymer electrolyte layer

[0239] The electrolyte solution from Example 1 was applied to the resulting positive electrode using a bar coater, air-dried for 10 minutes at 23 °C, and then dried for 30 minutes at 60 °C. Next, UV light was irradiated onto the film surface using a high-pressure mercury UV irradiator (product name: Handy 1000, commercially available from Marionetwork) to achieve a cumulative light dose of 5,000 mJ / cm².2 curing was performed. The film thickness after curing was 60 µm. Production of a secondary battery using the polymer electrolyte as bulk electrolyte, active material binder of the positive electrode and active material binder of the negative electrode.

[0240] The positive and negative electrodes coated with the polymer electrolyte were vacuum-dried at 80 °C for 48 hours. The polymer electrolyte film was then placed in an argon-purged glovebox (at a temperature of 25 °C and a dew point of -70 °C), and a window-frame-shaped polyimide film was applied to cover the outer edge of the positive electrode surface, forming a short-circuit prevention layer. Lamination was then performed so that the polymer electrolyte layer of the polymer electrolyte-coated positive electrode corresponded to the active material layer of the negative electrode.The laminate was inserted into the aluminium laminate foil and vacuum-packed to obtain a secondary battery according to Example 40, in which the polymer electrolyte of the present disclosure was used as the bulk electrolyte, the active material binder of the positive electrode and the active material binder of the negative electrode. Examples 38 to 40

[0241] Secondary batteries according to Examples 38 to 40 were manufactured in the same way as in Example 37, except that the electrolyte solutions (polymer electrolyte) were changed as shown in Table 7. The evaluation results, such as the charging rate, are shown in Table 7. Comparison example 1

[0242] The following materials were mixed and stirred as polymer electrolyte materials. ▪ Polyether monomethacrylate NK ester M-40G (commercially available from Shin-Nakamura Chemical Co., Ltd.): 70 parts by mass ▪ Polyether dimethacrylate 4G (commercially available from Shin-Nakamura Chemical Co., Ltd.): 30 parts by mass ▪ Lithium bis(trifluoromethanesulfonyl)imide (commercially available from Kishida Chemical Co., Ltd.): 10.0 parts by mass ▪ Initiator Omnirad184 (commercially available from IGM RESINS BV): 2.0 mass parts

[0243] Next, methyl ethyl ketone was added so that the total solids content was 60 wt%, and the mixture was then mixed by motor stirring to produce an electrolyte solution.

[0244] Next, a polymer electrolyte and a secondary battery were prepared in the same manner as in Example 1, according to Comparative Example 1. Comparative examples 2 to 6

[0245] 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 formulation amounts of polyether mono(meth)acrylate, polyether di(meth)acrylate, ionic compounds and supporting electrolytes were changed as shown in Table 4.

[0246] The secondary batteries in comparison examples 1 to 6 had a configuration in which the polymer electrolyte was used as a bulk electrolyte. The evaluation results, such as the charging rate, are shown in Table 6. [Table 4] Polyether mono(meth)acrylate Polyether di(meth)acrylate or tri(meth)acrylate Reactive ion Supportive electrolyte Nr. Mass parts Nr. Mass parts Nr. Mass parts Nr. Mass parts Comparative example 1 M-40G 70 4G 30 - - Li▪TFSI 10 Comparative example 2 - - 4G 100 C-1 15 Li▪TFSI 10 Comparative example 3 M-40G 30 4G 70 C-1 15 Li▪FSI 10 Comparative example 4 AM-130G 99 A-600 1 C-2 15 Li▪FSI 10 Comparative example 5 AM-90G 100 - - C-2 15 Li▪FSI 10 Comparative example 6 PA-500 70 APG-400 30 C-2 15 Li▪FSI 10

[0247] The structures, once the materials used have polymerized, are as follows.

[0248] M-40G: Methoxytetraethylene glycol methacrylate (in formula (1-1), R1: methyl group, R2: ethylene group, R3: methyl group, m1: 3, n1: 0 4G: Polyethylene glycol #200 dimethacrylate (in formula (2-1), R4: methyl group, R5: ethylene group, R6: ethylene group, m2: 4, n2: 0) APG-400: Polypropylene glycol #400-Diacrylate (in formula (2-1), R4: hydrogen atom, R5: propylene group, R6: propylene group, m2: 0, n2: 7) AM-90G, AM-130G and A-600 are as described above. All of the above materials are commercially available from Shin-Nakamura Chemical Co., Ltd. PA-500: Hydroxypolypropylene glycol monoacrylate (in formula (1-1), R1: hydrogen atom, R2: propylene group, R3: hydroxyl group, m1: 0, n1: 5), commercially available from TOHO Chemical Industry Co., Ltd. Comparative example 7

[0249] A secondary battery corresponding to Comparative Example 7 was manufactured in the same manner as in Example 33, except that 7 parts by mass of Kureha KF Polymer L #1120 (commercially available from Kureha Corporation) were used as the active material binder of the positive electrode. Comparative examples 8 to 10

[0250] Secondary batteries according to Comparative Examples 8 to 10 were prepared in the same manner as in Example 33, except that the types and formulation amounts of polyether mono(meth)acrylate, polyether di(meth)acrylate, ionic compounds and supporting electrolytes were changed as shown in Table 8.

[0251] The secondary batteries corresponding to comparison examples 7 to 10 had a configuration in which the polymer electrolyte was used as the active material binder of the positive electrode. The evaluation results, such as the charging rate, are shown in Table 8. Comparative examples 11 to 14

[0252] Secondary batteries corresponding to Comparative Examples 11 to 14 were prepared in the same manner as in Example 37, except that the types and formulation amounts of polyether mono(meth)acrylate, polyether di(meth)acrylate, ionic compounds and supporting electrolytes were changed as shown in Table 8.

[0253] The secondary batteries corresponding to comparison examples 11 to 14 had a configuration in which the polymer electrolyte was used as the active material binder of the positive electrode, as the bulk electrolyte, and as the active material binder of the negative electrode. The evaluation results, such as the charging rate, are shown in Table 8.

[0254] The polymer electrolytes and secondary batteries obtained 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 and 5-2, Table 6, Table 7, and Table 8. [Table 5-1] Volume swelling ratio (%) Average number of added moles ion ratio Ionic conductivity (S / cm) Meo Mpo Mpo% A / (A+B) 25°C 5°C Example 1 42 44 7 16 0,80 6,35×10 -6 5,24×10 -7 Example 2 45 41 7 16 0,80 1,41×10 -5 2,16×10 -6 Example 3 71 78 6 8 0,80 7,13×10 -5 6,11×10 -5 Example 4 65 28 4 14 0,80 6,63×10 -5 9,89×10 -6 Example 5 84 74 14 19 0,80 6,28×10 -5 2,71×10 -5 Example 6 80 76 0 0 0,80 8,72×10 -5 1,98×10 -5 Example 7 79 30 6 20 0,80 9,11×10 -5 4,12×10 -5 Example 8 73 16 3 18 0,80 4,01×10 -5 1,13×10 -5 Example 9 76 7 1 17 0,80 2,97×10 -5 7,90×10 -6 Example 10 79 30 6 20 0,80 8,87×10 -5 3,12×10 -5 Example 11 79 30 6 20 0,80 8,68×10 -5 3,52×10 -5 Example 12 50 34 6 19 0,80 3,92×10 -5 6,86×10 -6 Example 13 51 21 0 1 0,80 1,69×10 -5 3,04x10 -6 Example 14 52 16 3 18 0,80 1,86×10 -5 3,11×10 -6 Example 15 49 11 7 68 0,80 1,42×10 -5 3,62×10 -6 Example 16 93 16 3 18 0,80 4,25×10 -5 4,99×10 -6 Example 17 104 17 3 16 0,80 7,45×10 -5 3,14×10 -6 Example 18 113 20 3 16 0,80 6,01×10 -5 4,27×10 -6 Example 19 94 16 3 16 0,80 1,69×10 -5 5,00×10 -6 Example 20 95 16 3 20 0,80 3,42×10 -5 7,53×10 -6 Example 21 112 9 0 0 0,80 2,63×10 -6 8,61× 10 -7 Example 22 115 13 0 0 0,80 5,76×10 -6 2,63×10 -6 Example 23 111 17 3 17 0,80 8,97×10 -6 5,49×10 -6 Example 24 109 45 0 0 0,80 8,44×10 -6 4,18×10 -6 Example 25 104 34 6 19 0,50 6,12×10 -5 1,77×10 -5 Example 26 104 34 6 19 0,67 7,92×10 -5 2,56×10 -5 Example 27 103 34 6 19 0,75 1,13×10 -4 6,75×10 -5 Example 28 104 34 6 19 0,80 3,12×10 -4 8,99×10 -5 Example 29 106 34 6 19 0,87 1,57×10 -4 6,86×10 -5 Example 30 105 34 6 19 0,95 6,93×10 -5 1,01×10 -5 Example 31 116 4 3 72 0,95 1,55×10 -6 4,70×10 -7 Example 32 110 11 8 72 0,95 1,73×10 -6 4,40×10 -7 [Table 5-2] Charging rate Impact resistance test: Number of short circuits in secondary battery Assessment of the occurrence of short circuits During charging During unloading 25 °C 60 °C Number of cycles electrode surface Example 1 0,15C 0,15C 0 / 5 0 / 5 62 Small protrusions observed Example 2 0,20C 0,20C 0 / 5 1 / 5 68 Small protrusions observed Example 3 0,20C 0,15C 0 / 5 0 / 5 88 Small protrusions observed Example 4 0,20C 0,20C 0 / 5 0 / 5 84 Small protrusions observed Example 5 0,20C 0,20C 0 / 5 0 / 5 >100 Almost smooth Example 6 0,20C 0,20C 0 / 5 0 / 5 >100 Almost smooth Example 7 0,20C 0,20C 0 / 5 0 / 5 >100 Almost smooth Example 8 0,20C 0,20C 0 / 5 0 / 5 >100 Almost smooth Example 9 0,20C 0,20C 0 / 5 0 / 5 >100 Almost smooth Example 10 0,20C 0,20C 0 / 5 0 / 5 >100 Almost smooth Example 11 0,20C 0,20C 0 / 5 0 / 5 >100 Almost smooth Example 12 0,20C 0,20C 0 / 5 0 / 5 >100 Very small protrusions observed Example 13 0,20C 0,20C 0 / 5 0 / 5 >100 Almost smooth Example 14 0,20C 0,20C 0 / 5 0 / 5 >100 Very small protrusions observed Example 15 0,20C 0,20C 0 / 5 0 / 5 >100 Almost smooth Example 16 0,20C 0,25C 0 / 5 0 / 5 >100 Almost smooth Example 17 0,20C 0,20C 0 / 5 0 / 5 >100 Almost smooth Example 18 0,20C 0,20C 0 / 5 0 / 5 >100 Almost smooth Example 19 0,20C 0,20C 0 / 5 0 / 5 >100 Almost smooth Example 20 0,20C 0,20C 0 / 5 0 / 5 >100 Almost smooth Example 21 0,15C 0,15C 0 / 5 0 / 5 >100 Very small protrusions observed Example 22 0,20C 0,20C 0 / 5 0 / 5 >100 Almost smooth Example 23 0,20C 0,20C 0 / 5 0 / 5 >100 Almost smooth Example 24 0,20C 0,20C 0 / 5 0 / 5 >100 Almost smooth Example 25 0,25C 0,25C 0 / 5 0 / 5 >100 Almost smooth Example 26 0,30C 0,25C 0 / 5 0 / 5 >100 Almost smooth Example 27 0,45C 0,40C 0 / 5 0 / 5 >100 Almost smooth Example 28 0,50C 0,45C 0 / 5 0 / 5 >100 Almost smooth Example 29 0,45C 0,40C 0 / 5 0 / 5 >100 Almost smooth Example 30 0,30C 0,25C 0 / 5 0 / 5 >100 Almost smooth Example 31 0,15C 0,15C 0 / 5 1 / 5 >100 Almost smooth Example 32 0,15C 0,20C 0 / 5 1 / 5 >100 Almost smooth

[0255] In Tables 5-1, 5-2 and 6, Mpo% is the ratio of the average number of moles Mpo added to the average number of moles Meo added. [Table 6] Volume swelling ratio (%) Average number of added moles ion ratio Ionic conductivity (S / cm) Meo Mpo Mpo% A / (A+B) 25 °C 5 °C Comparative example 1 56 3 0 0 - 6,82×10 -7 7,86×10 -8 Comparative example 2 28 3 0 0 0,40 8,17×10 -7 6,60×10 -8 Comparative example 3 29 3 0 0 0,40 6,54×10 -7 6,25×10 -8 Comparative example 4 146 13 0 0 0,40 4,64×10 -5 9,41×10 -7 Comparative example 5 -(Solved) 9 0 0 0,40 3,15×10 -5 2,03×10 -7 Comparative example 6 58 0 6 - 0,40 1,83×10 -7 8,93×10 -8 Charging rate Impact resistance test: Number of short circuits in secondary battery Assessment of the occurrence of short circuits While charging During unloading 25 °C 60 °C Number of cycles electrode surface Comparative example 1 0,05C 0,05C 0 / 5 0 / 5 48 Small dendrites observed Comparative example 2 0,05C> - 0 / 5 0 / 5 20 Dendrites observed Comparative example 3 0,05C 0,05C 0 / 5 0 / 5 20 Dendrites observed Comparative example 4 0,20C 0,20C 0 / 5 4 / 5 17 Dendrites observed Comparative example 5 0,20C 0,20C 0 / 5 5 / 5 20 Dendrites observed Comparative example 6 0,05C> - 0 / 5 0 / 5 23 Dendrites observed

[0256] The polymer electrolytes according to Examples 1 to 32 had a polymer structure that, in addition to the structure of formula (1) and at least one of the structures of formulas (2) and (3), included the structure of formula (4), and the volume swelling ratio was 30% to 120%. Therefore, they exhibited high ionic conductivity at both 25°C and 5°C. Furthermore, the secondary batteries in which the polymer electrolyte according to Examples 1 to 32 was used as the bulk electrolyte exhibited both a high charging rate and high impact resistance at high temperatures.

[0257] Additionally, in the polymer electrolytes according to Examples 1 to 32, the volume swelling ratio was 30% to 120% and A / (A+B) was 0.50 or higher. Therefore, the number of cycles until a short circuit occurred was large, and the service life of the secondary batteries was extended.

[0258] Additionally, examples, including example 7, in which the mass ratio α:β of content A of the structure of formula (1) to content B of formula (2) in the polymer structure was 70:30 to 98:2, m1+n1 in formula (1-1) 14 to 58 and m2+n2 in formula (2-1) 14 to 58, showed a particularly high ionic conductivity and also favorable charging rates of the secondary batteries.

[0259] On the other hand, the polymer electrolytes according to Comparative Example 1, which does not have a structure of formula (4) in the polymer structure, Comparative Examples 2 and 6, which do not have a structure of formula (1), and Comparative Example 3, which had a volume swelling ratio of less than 30%, showed low ionic conductivity, and the charging rates of the secondary batteries were very low. Additionally, in Comparative Examples 2 to 6, where A / (A+B) was less than 0.50, the number of cycles until a short circuit occurred was low, and dendrites were observed on the surface of the battery electrode.

[0260] In addition, the secondary batteries that used the polymer electrolytes according to comparison examples 4 and 5, in which the volume swelling ratio was more than 120% or there was no 3D cross-linking, showed a significant decrease in impact resistance at high temperatures. [Table 7] Polymer electrolyte Polymer electrolyte specification part Charging rate Impact resistance test: Number of short circuits in secondary battery During the loading During unloading 25 °C 60 °C Example 33 Like example 1 Active material binder of the positive electrode 0,15C 0,15C 0 / 5 0 / 5 Example 34 Like example 7 0,20C 0,20C 0 / 5 0 / 5 Example 35 Like example 12 0,20C 0,20C 0 / 5 0 / 5 Example 36 Like example 29 0,45C 0,40C 0 / 5 0 / 5 Example 37 Like example 1 Bulk electrolyte Active material binder of the positive electrode Active material binder of the negative electrode 0,15C 0,15C 0 / 5 0 / 5 Example 38 Like example 7 0,20C 0,20C 0 / 5 0 / 5 Example 39 Like example 12 0,20C 0,20C 0 / 5 0 / 5 Example 40 Like example 29 0,45C 0,40C 0 / 5 0 / 5 [Table 8] Polymer electrolyte Polymer electrolyte specification part Charging rate Impact resistance test: Number of short circuits in secondary battery During the loading During unloading 25 °C 60 °C Comparative example 7 -(KF Polymer L#1120) Active material binder of the positive electrode 0,05C> - 0 / 5 0 / 5 Comparative example 8 See comparative example 1 0,05C 0,05C 0 / 5 0 / 5 Comparative example 9 See comparison example 2 0,05C 0,05C 0 / 5 0 / 5 Comparative example 10 See comparative example 6 0,05C 0,05C 0 / 5 0 / 5 Comparative example 11 See comparative example 1 Bulk electrolyte Active material binder of the positive electrode Active material binder of the negative electrode 0,05C> - 0 / 5 0 / 5 Comparative example 12 See comparative example 3 0,05C> - 0 / 5 0 / 5 Comparative example 13 See comparison example 4 0,25C 0,20C 0 / 5 5 / 5 Comparative example 14 See comparative example 5 0,25C 0,20C 0 / 5 5 / 5

[0261] Similar to the case where the polymer electrolyte was used as a bulk electrolyte, the secondary batteries according to Examples 33 to 36, in which the polymer electrolyte of the present disclosure was used as the active material binder of the positive electrode, and the secondary batteries according to Examples 37 to 40, in which the polymer electrolyte was used as the active material binder of the positive electrode, the bulk electrolyte and the active material binder of the negative electrode, exhibited both a high charging rate and high impact resistance at high temperatures.

[0262] On the other hand, the secondary batteries according to comparison examples 8 and 11, which did not exhibit a structure of formula (4) in the polymer structure, comparison examples 9 and 10, which did not exhibit a structure of formula (1), and comparison example 12, in which the volume swelling ratio was less than 30%, showed a result with a low charging rate. Additionally, the secondary batteries according to comparison examples 13 and 14, in which the volume swelling ratio was greater than 120 or there were no 3D cross-links, showed a significant decrease in impact resistance at high temperatures.

[0263] While the present disclosure has been described with reference to embodiments, it is to be understood that the present disclosure is not limited to the disclosed embodiments. The scope of the following claims is to be interpreted as broadly as possible to encompass all such modifications and equivalent structures and functions.

[0264] This application claims priority over 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, which are hereby incorporated in their entirety by reference into this application. REFERENCE MARK LIST 1 secondary battery 2 Current collector of the positive electrode 3 Active material of the positive electrode 4 Active material binder of the positive electrode 5 Conductivity Aids 6 Positive electrode 7 Bulk electrolyte 8 Active material of the negative electrode 9 Current collector of the negative electrode 10 Negative electrode 11 Active material binder of the negative electrode QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2017-090677

[0005] WO 2004 / 027789

[0005] JP 2009-104891

[0005] JP 2023-127680

[0264] JP 2024-100598

[0264] JP 2024-110667

[0264]

Claims

Polymer electrolyte, wherein the polymer electrolyte comprises a polymer and an alkali metal salt, the alkali metal salt comprising an alkali metal salt which, as an anion, includes at least one selected from the group consisting of bis(trifluoromethanesulfonyl)imide, bis(fluorosulfonyl)imide and hexafluorophosphate, the polymer having 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), a structure represented by the following formula (3), and a structure represented by the following formula (4), where the total number of moles of the anions in the alkali metal salt contained per unit mass of the polymer electrolyte is A and the number of moles of the sulfonylimide groups bonded to the polymer is B, A and B satisfy the relationship of the following formula (X), 0.50 ≤ A / ( A + B ) and the volume swelling ratio of the polymer electrolyte, determined by a methyl ethyl ketone immersion process, is 30% to 120%: (In formula (1) R 1 a hydrogen atom or a methyl group. R 2 is a linear or branched alkylene group containing 1 to 6 carbon atoms. R 3 is an alkyl group that has 1 to 6 carbon atoms. In formula (2) R 4 Each independently contains either a hydrogen atom or a methyl group. R 5 and R 6 Each is independently a linear or branched alkylene group containing 1 to 6 carbon atoms. In formula (3) R 7 Each independently contains either a hydrogen atom or a methyl group. R 8 , R 9 and R 10 Each is independently a linear or branched alkylene group containing 1 to 6 carbon atoms. R 11 is a trivalent organic group that has 1 to 6 carbon atoms. In formulas (1) to (3), A1, B1, D1, D2 and D3 are each independently a compound group containing at least one compound formed by (-CH). 2 CH 2 -O-) exhibits the ethylene oxide structure shown. (In formula (4) R 12 a hydrogen atom or a methyl group. R 13 is a divalent compound group. R 14 is a fluorine atom or a perfluoroalkyl group containing 1 to 4 carbon atoms. X + is at least one selected from the group consisting of a lithium ion, a sodium ion and a potassium ion. The sulfonylimide group is a functional group represented by the following formula (S). In formula (S), R is a fluorine atom or a perfluoroalkyl group having 1 to 4 carbon atoms. Polymer electrolyte according to claim 1, wherein A and B satisfy 0.65≤A / (A+B)≤0.

96. Polymer electrolyte according to claim 1 or 2, wherein the average number of added moles Meo of the ethylene oxide structure per mole of (meth)acryloyl residue in the polymer is 2.5 moles or more. Polymer electrolyte according to one of claims 1 to 3, wherein A1, B1, D1, D2 and D3 each independently additionally have a propylene oxide structure represented by (-CH2CH(CH3)-O-). Polymer electrolyte according to claim 4, wherein in the polymer the average number of added moles Mpo of the propylene oxide structure per mole of (meth)acryloyl residue is 5% to 25% of the average number of added moles Meo of the ethylene oxide structure per mole of (meth)acryloyl residue. Polymer electrolyte according to any one of claims 1 to 5, wherein, where the mass fraction of the structure represented by formula (1) in the polymer included in the polymer electrolyte is α and the total mass fraction of the structure represented by formula (2) and the structure represented by formula (3) is β, the mass ratio α:β is 70:30 to 98:

2. 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 a hydrogen atom or a methyl group. R 2 is a linear or branched alkylene group containing 1 to 6 carbon atoms. R 3 is an alkyl group containing 1 to 6 carbon atoms. m1 and n1 are average numbers of moles added; m1 is an integer of 1 or more, and n1 is an integer of 0 or more. The arrangement of a by (-CH 2 -CH 2 -O-) represented ethylene oxide structure and a structure represented by (-CH 2 -CH(CH 3 The propylene oxide structure shown ()-O-) can be a block copolymer or a statistical copolymer.) (In formula (2-1) R 4 Each independently contains either a hydrogen atom or a methyl group. R 5 and R 6 Each independent alkylene group is a linear or branched group containing 1 to 6 carbon atoms. m2 and n2 are average numbers of added moles, m2 is an integer of 1 or more, and n2 is an integer of 0 or more. The arrangement of a (-CH) 2 -CH 2 -O-) represented ethylene oxide structure and a structure represented by (-CH 2 -CH(CH 3 The propylene oxide structure shown (-O-) can be a block copolymer or a statistical copolymer. The chain arranged between two -COO- can additionally have a diol structure containing 1 to 6 carbon atoms. (In formula (3-1) R 7 Each independently contains either a hydrogen atom or a methyl group. R 8 , R 9 and R 10 Each is independently a linear or branched alkylene group containing 1 to 6 carbon atoms. R 11 is a trivalent organic group containing 1 to 6 carbon atoms. m3 and n3 are average numbers of added moles, m3 are each independently an integer of 1 or more, and n3 are each independently an integer of 0 or more. The arrangement of a group formed by (-CH 2 -CH 2 -O-) represented ethylene oxide structure and a structure represented by (-CH 2 -CH(CH 3 The propylene oxide structure shown (-O-) can be a block copolymer or a statistical copolymer. The chain arranged between -COO- and R11 can additionally have a diol structure containing 1 to 6 carbon atoms. Polymer electrolyte according to claim 7, wherein in the polymer electrolyte m1+n1 in formula (1-1) are 14 to 58, and m2+n2 in formula (2-1) and / or m3+n3 in formula (3-1) are 14 to 58. Polymer electrolyte according to claim 7 or 8, wherein in the polymer electrolyte m1:n1 in formula (1-1) is 80:20 to 95:5, and m2:n2 in formula (2-1) and / or m3:n3 in formula (3-1) is 80:20 to 95:

5. 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, based on a total content 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), is 1 to 25 parts by mass. Polymer electrolyte according to any one of claims 1 to 10, wherein the polymer electrolyte is a dry polymer electrolyte. Secondary battery comprising a positive electrode, a bulk electrolyte and a negative electrode, wherein at least one of the group consisting of the positive electrode, the bulk electrolyte and the negative electrode comprises the polymer electrolyte according to any one of claims 1 to 11. A secondary battery comprising a positive electrode, a bulk electrolyte, and a negative electrode, wherein the secondary battery fulfills at least one of the following (i) to (iii): (i) the positive electrode comprises an active material of the positive electrode and an active material binder of the positive electrode that fixes the active material of the positive electrode, and the active material binder of the positive electrode is 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 comprises an active material of the negative electrode and an active material binder of the negative electrode that fixes the active material of the negative electrode, and the active material binder of the negative electrode is the polymer electrolyte according to any one of claims 1 to 11.

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