Polymer electrolyte composite material, composition for lithium ion secondary battery electrode mixture layer, electrode for lithium ion secondary battery, and lithium ion secondary battery

Abstract

To provide a polymer electrolyte composite material capable of being filled into generated cracks in order to solve the fear that the cracks that are generated inside the active material layer in the anode or cathode of a lithium ion secondary battery may cause deterioration of battery characteristics.SOLUTION: A polymer electrolyte composite material comprises at least: a polyether copolymer comprising al least a constitutional unit (A) derived from ethylene oxide and represented by the following formula (1) and a constitutional unit (B) derived from an epoxy compound and represented by the following formula (2); a cyclic carbonate compound represented by the following formula (4); and a lithium salt. In 100 mol% of the polyether copolymer, the polymer composition includes 1-79 mol% of the constitutional unit (A) and 20-98 mol% of the constitutional unit (B): CH2-CH2-O (1) and R1-CH-CH2-O (2) where R1 represents a C1-12 alkyl group, a cycloalkyl group, or an aryl group; and R2-CH-CH2-O (4), where R2 represents a group having an ethylenic unsaturated group.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polymer electrolyte composite material for a lithium ion secondary battery.

[0002] Lithium-ion secondary batteries are used in a wide variety of applications, large and small, across a wide range of industries. Liquid-type lithium-ion secondary batteries, the most common type today, are becoming increasingly compact and lightweight, resulting in improved performance for devices like mobile phones. However, they face challenges such as declining energy density and capacity loss due to repeated charging and discharging. Furthermore, large lithium-ion secondary batteries used in hybrid vehicles pose a risk of fire due to electrolyte leakage. To address these challenges, active research has been conducted in recent years on the development of materials for all-solid-state lithium-ion secondary batteries.

[0003] All-solid-state lithium-ion secondary batteries have the advantage of not using electrolyte, eliminating concerns about leakage. However, due to the lack of adhesion between solids, gaps may form in the electrolyte layer or active material layer, potentially causing a deterioration in battery performance. Patent Document 1 suggests that the electrode material, surrounded by the electrolyte that fills the porous space within the electrode, contains at least 50% solid electrolyte relative to the gaps between particles, reducing internal resistance and helping the battery achieve a longer cycle life. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2022-535256 Summary of the Invention [Problem to be solved by the invention]

[0005] As shown in Patent Document 1, even if the gaps between particles in an electrode are filled with a solid electrolyte, it is extremely difficult to completely fill the gaps, and there remains a risk of gaps occurring due to the low adhesiveness between solids. [Means for solving the problem]

[0006] The present inventors have conducted extensive research to solve the above problems and have found that a polymer electrolyte composite material containing at least a polyether copolymer, a cyclic carbonate compound, and a lithium salt has high stability against inorganic solid electrolytes and has ionic conductivity equivalent to that of inorganic solid electrolytes. Based on this finding, the present invention was completed through further research.

[0007] That is, the present invention provides the following configuration. Request 1 A polymer electrolyte composite material comprising at least a polyether copolymer containing at least a structural unit (A) derived from ethylene oxide represented by the following formula (1) and a structural unit (B) derived from an epoxy compound represented by the following formula (2), a cyclic carbonate compound represented by the following formula (4), and a lithium salt: A polymer electrolyte composite material having a polymerization composition in which the structural unit (A) accounts for 1 to 79 mol % and the structural unit (B) accounts for 20 to 98 mol % of the polyether copolymer (100 mol %). [ka] (1) [ka] (2) [In the formula, R 1 is an alkyl group, a cycloalkyl group, or an aryl group having 1 to 12 carbon atoms.] [ka] (4) [In the formula, R 3 is a linear or branched alkyl group having 1 to 8 carbon atoms.] Section 2 Item 2. The polyether copolymer according to Item 1, further comprising, as a polymerization composition thereof, a structural unit (C) derived from a compound having an ethylenically unsaturated group, represented by the following formula (3), wherein the structural unit (C) accounts for 0.1 to 20 mol % of 100 mol % of the polyether copolymer: [ka] (3) [In the formula, R 2 is a group having an ethylenically unsaturated group.] Section 3 Item 2. The polymer electrolyte composite material according to Item 1, comprising at least 4 parts by mass to 70 parts by mass of a polyether copolymer, 4 parts by mass to 90 parts by mass of a cyclic carbonate compound represented by Formula (4), and 2 parts by mass to 90 parts by mass of a lithium salt compound, relative to 100 parts by mass of the polymer electrolyte composite material. Section 4 Item 1. A composition for an electrode mixture layer of a lithium secondary battery, comprising at least the polymer electrolyte composite material according to Item 1, an active material, and an inorganic solid electrolyte. Section 5 Item 5. A lithium ion secondary battery electrode mixture layer produced using the lithium ion secondary battery electrode mixture layer composition according to item 4. Section 6 Item 6. A lithium ion secondary battery electrode produced using the lithium ion secondary battery electrode mixture layer according to Item 5. Section 7 Item 7. A lithium ion secondary battery produced using the electrode for a lithium ion secondary battery according to Item 6. [Effects of the Invention]

[0008] According to the present invention, the polymer electrolyte composite material of the present invention exhibits high stability against inorganic solid electrolytes and further has ionic conductivity equivalent to that of inorganic solid electrolytes. A lithium ion secondary battery using an electrode for a lithium ion secondary battery containing the polymer electrolyte composite material of the present invention exhibits high battery properties, particularly a high cycle capacity retention rate. DETAILED DESCRIPTION OF THE INVENTION

[0009] <Polymer electrolyte composite material> The polymer electrolyte composite material of the present invention has a composition including at least a polyether copolymer containing at least a constituent unit derived from ethylene oxide represented by the following formula (1) and a constituent unit derived from an epoxy compound represented by the following formula (2), a cyclic carbonate compound, and a lithium salt. [ka] (1) [ka] (2) [In the formula, R 1 is an alkyl group, a cycloalkyl group, or an aryl group having 1 to 12 carbon atoms.]

[0010] <Polyether copolymer> The compound of formula (1) is ethylene oxide, which is a basic chemical product and is readily available commercially.

[0011] In 100 mol% of the polyether copolymer of the present invention, the lower limit of the ethylene oxide-derived structural units represented by formula (1) is preferably 1 mol% or more, more preferably 10 mol% or more, even more preferably 20 mol% or more, particularly preferably 30 mol% or more, and particularly preferably 40 mol% or more. The upper limit is preferably 79 mol% or less, more preferably 75 mol% or less, even more preferably 70 mol% or less, and particularly preferably 60 mol% or less. By being within these ranges, the ionic conductivity of the polyether copolymer can be ensured.

[0012] In the structural unit derived from the epoxy compound represented by the above formula (2), the side chain is preferably, for example, an alkyl group, a cycloalkyl group, or an aryl group having 1 to 12 carbon atoms, and more preferably an alkyl group having 1 to 12 carbon atoms.

[0013] Examples of compounds having an alkyl group having 1 to 12 carbon atoms in the side chain include propylene oxide, butylene oxide, 1,2-epoxypentane, 1,2-epoxyhexane, 1,2-epoxyheptane, 1,2-epoxyoctane, 1,2-epoxydecane, and 1,2-epoxydodecane. Among these, propylene oxide, butylene oxide, 1,2-epoxypentane, and 1,2-epoxyhexane are preferred, and propylene oxide and butylene oxide are more preferred. These compounds may be used alone or in combination of two or more.

[0014] In 100 mol% of the polyether copolymer of the present invention, the constituent units derived from the epoxy compound represented by formula (2) are preferably 20 mol% or more as a lower limit, more preferably 25 mol% or more, and even more preferably 30 mol% or more. The upper limit is preferably 98 mol% or less, more preferably 90 mol% or less, even more preferably 80 mol% or less, particularly preferably 70 mol% or less, and especially preferably 60 mol% or less. When the polyether copolymer is within these ranges, there is no reaction even when the inorganic solid electrolyte comes into contact with the polyether copolymer, and therefore the polyether copolymer has high stability with respect to the inorganic solid electrolyte.

[0015] The polyether copolymer used in the polymer electrolyte composite composition of the present invention is produced by a polymerization reaction as follows: (A): A repeating unit derived from a monomer of formula (1) [ka] (A) and (B): a repeating unit derived from a monomer of formula (2). [ka] (B) [In the formula, R 1 is an alkyl group, a cycloalkyl group, or an aryl group having 1 to 12 carbon atoms. It consists of:

[0016] Furthermore, as other structural units, a structural unit derived from a compound having an ethylenically unsaturated bond, as represented by the following formula (3), may be included. [ka] (3) [In the formula, R 2 is a group having an ethylenically unsaturated group.]

[0017] In the structural unit derived from a compound having an ethylenically unsaturated bond represented by formula (3), R 2 Examples of the hydrocarbon group may be a hydrocarbon group having a double bond, in particular a cyclic hydrocarbon group having a double bond, or CH2=CH-A 1 -(A 1 may be a direct bond or a hydrocarbon group having 1 to 30 carbon atoms, such as an alkylene group).

[0018] When the polyether copolymer of the present invention contains a structural unit derived from a compound having an ethylenically unsaturated bond represented by formula (3), in addition to the above (A) and (B), (C): Repeating unit derived from the monomer of formula (3) [ka] (C) [In the formula, R 2 is a substituent containing a group having an ethylenically unsaturated group. The configuration will include:

[0019] Examples of the structural unit derived from the compound having an ethylenically unsaturated bond represented by formula (3) include allyl glycidyl ether, 4-vinylcyclohexyl glycidyl ether, α-terpinyl glycidyl ether, cyclohexenylmethyl glycidyl ether, p-vinylbenzyl glycidyl ether, allylphenyl glycidyl ether, vinyl glycidyl ether, 3,4-epoxy-1-butene, 3,4-epoxy-1-pentene, 4,5-epoxy-2-pentene, 1,2-epoxy-5,9-cyclododecadiene, 3,4-epoxy-1-vinylcyclohexene, 1,2-epoxy-5-cyclooctene, glycidyl acrylate, glycidyl methacrylate, glycidyl sorbate, glycidyl cinnamate, glycidyl crotonate, and glycidyl-4-hexenoate. Of these, allyl glycidyl ether, vinyl glycidyl ether, glycidyl acrylate, and glycidyl methacrylate are preferred.

[0020] In 100 mol% of the polyether copolymer of the present invention, the constituent units derived from the compound having an ethylenically unsaturated bond represented by formula (3) are preferably 0.1 mol% or more as a lower limit, more preferably 0.5 mol% or more, and even more preferably 1 mol% or more. The upper limit is preferably 20 mol% or less, more preferably 15 mol% or less, even more preferably 10 mol% or less, and particularly preferably 5 mol% or less. Within these ranges, the strength of the polyether copolymer after crosslinking is increased, and the shape of the polymer electrolyte composite material is easily maintained.

[0021] In 100 mol% of the polyether copolymer of the present invention, the total of the structural units derived from the compounds represented by formulas (1) to (3) is preferably 60 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and most preferably 90 mol% or more. There is no particular upper limit, and it may be 100 mol%.

[0022] The molar ratio of the polymerization composition of the polyether copolymer is 1The integral value of each unit is calculated by H-NMR, and the composition can be determined from the calculation results.

[0023] The polyether copolymer may be either a block copolymer or a random copolymer, with the random copolymer being preferred since it has a greater effect of reducing the crystallinity of polyethylene oxide.

[0024] Regarding the weight-average molecular weight of the polyether copolymer, the lower limit of the weight-average molecular weight is preferably 100,000 or more, more preferably 150,000 or more, and even more preferably 300,000 or more, and the upper limit of the weight-average molecular weight is preferably 3,000,000 or less, more preferably 2,700,000 or less, and even more preferably 2,500,000 or less. The molecular weight of the polyether copolymer was measured by gel permeation chromatography (GPC), and the weight-average molecular weight was calculated in terms of standard polystyrene. The solvent used was DMF (N,N-dimethylformamide).

[0025] The polyether copolymer of the present invention can be synthesized as follows. As a ring-opening polymerization catalyst, a coordinated anion initiator such as an organoaluminum-based catalyst system, an organozinc-based catalyst system, or an organotin-phosphate ester condensate catalyst system, or a catalyst containing K as a counter ion, is used. + A polyether copolymer can be obtained by reacting each monomer with an anionic initiator such as potassium alkoxide containing potassium hydroxide, diphenylmethyl potassium, or potassium hydroxide in the presence or absence of a solvent at a reaction temperature of 10 to 120°C while stirring. From the viewpoint of the degree of polymerization and the properties of the resulting copolymer, a coordinated anionic initiator is preferred, and among them, an organotin-phosphate ester condensate catalyst system is particularly preferred because of its ease of handling.

[0026] The content of the polyether copolymer in 100 parts by mass of the polymer electrolyte composite material of the present invention is preferably 4 parts by mass or more, more preferably 5 parts by mass or more, even more preferably 6 parts by mass or more, and particularly preferably 7 parts by mass or more, as a lower limit. The upper limit is preferably 70 parts by mass or less, more preferably 65 parts by mass or less, even more preferably 60 parts by mass or less, and particularly preferably 55 parts by mass or less. Within these ranges, the liquid retention capacity of the polyether copolymer is sufficiently maintained, and the cyclic carbonate compound, which is a liquid compound, does not leak out of the electrode mixture layer.

[0027] <Cyclic carbonate compounds> The cyclic carbonate compound represented by the following formula (4) contained in the polymer electrolyte composite composition of the present invention preferably has a linear alkyl group or a branched alkyl group having 1 to 8 carbon atoms as a side chain, more preferably a linear alkyl group having 1 to 8 carbon atoms, and even more preferably a linear alkyl group having 1 to 4 carbon atoms. [ka] (4) [In the formula, R 3 is a linear or branched alkyl group having 1 to 8 carbon atoms.]

[0028] Examples of the linear alkyl group having 1 to 8 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, an n-pentyl group, an n-hexyl group, an n-heptyl group, and an n-octyl group. Among these, a methyl group, an ethyl group, an n-propyl group, and an n-butyl group are preferred, a methyl group, an ethyl group, an n-propyl group, and an n-butyl group are more preferred, and a methyl group and an ethyl group are even more preferred. Specific examples of the compound include propylene carbonate and butylene carbonate. These may be used alone or in combination of two or more.

[0029] Examples of branched alkyl groups having 1 to 8 carbon atoms include an isopropyl group, an isobutyl group, a sec-butyl group, a t-butyl group, a 2-methylbutyl group, a sec-pentyl group, a neopentyl group, a neohexyl group, and a 2-ethylhexyl group.

[0030] The content of the cyclic carbonate compound in 100 parts by mass of the polymer electrolyte composite material of the present invention is preferably 4 parts by mass or more, more preferably 5 parts by mass or more, even more preferably 6 parts by mass or more, and particularly preferably 7 parts by mass or more, as a lower limit. The upper limit is preferably 90 parts by mass or less, more preferably 88 parts by mass or less, even more preferably 86 parts by mass or less, and particularly preferably 84 parts by mass or less. Within these ranges, the viscosity of the polymer electrolyte composite material becomes suitable, and gaps occurring in the electrode mixture layer can be easily filled.

[0031] <Lithium salt compounds> The lithium salt compound contained in the polymer electrolyte composite material of the present invention is a lithium salt compound having a wide potential window, such as those commonly used in lithium-ion secondary batteries. Examples include, but are not limited to, LiBF, LiPF, LiClO, LiCFSO, LiN(FSO), LiN(CFSO), LiN(CFS0), and LiN[CFSC(CFS0)]. These compounds may be used alone or in combination.

[0032] The content of the lithium salt compound in 100 parts by mass of the polymer electrolyte composite material of the present invention is preferably 2 parts by mass or more, more preferably 3 parts by mass or more, even more preferably 4 parts by mass or more, and particularly preferably 5 parts by mass or more, as a lower limit. The upper limit is preferably 90 parts by mass or less, preferably 85 parts by mass or less, and even more preferably 80 parts by mass or less. If the content is too low, sufficient ionic conductivity cannot be ensured, adversely affecting the cycle characteristics of a solid-state battery. If the content is too high, the mechanical strength of the polymer electrolyte composite material decreases, which can lead to dendrite precipitation and the risk of short-circuiting.

[0033] In 100 parts by mass of the polymer electrolyte composite material of the present invention, the total content of the polyether copolymer, the cyclic carbonate compound, and the lithium salt is preferably 60 parts by mass or more, more preferably 70 parts by mass or more, even more preferably 80 parts by mass or more, and most preferably 90 parts by mass or more. There is no particular upper limit, and it may be 100 parts by mass.

[0034] When the polyether copolymer of the present invention contains a structural unit derived from a compound having an ethylenically unsaturated bond represented by formula (3), it is preferable to use a crosslinking agent or crosslinking aid such as a photoinitiator or a thermal polymerization initiator. The strength of the electrode mixture layer can be increased by crosslinking the polymer electrolyte composite material blended in the electrode mixture layer described below by applying heat or irradiating it with active energy rays such as ultraviolet rays.

[0035] Examples of photoinitiators that can be used in the present invention include alkylphenones, benzophenones, acylphosphine oxides, titanocenes, triazines, bisimidazoles, and oxime esters. Preferably, alkylphenones, benzophenones, and acylphosphine oxides are used as photoinitiators. Two or more of the above-mentioned compounds can be used in combination as the photoinitiator.

[0036] Examples of thermal polymerization initiators that can be used in the present invention include radical initiators selected from organic peroxides, azo compounds, etc. Preferably, the organic peroxides include ketone peroxides, peroxyketals, hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxyesters, etc., and the azo compounds include azonitrile compounds, azoamide compounds, azoamidine compounds, etc. More preferably, organic peroxide initiators are used, and two or more of these compounds can be used in combination.

[0037] When a photoreaction initiator or a thermal polymerization initiator is used, the amount is preferably in the range of 0.1 to 10 parts by mass, more preferably 0.1 to 4.0 parts by mass, per 100 parts by mass of the polyether copolymer.

[0038] In the present invention, a crosslinking coagent may be used in combination with a photoinitiator or a thermal polymerization initiator. The crosslinking coagent is usually a polyfunctional compound (e.g., a compound containing at least two CH2=CH-, CH2=CH-CH2-, or CF2=CF-).

[0039] When a crosslinking aid is used, the amount is preferably in the range of 0.1 to 30 parts by mass, more preferably 0.5 to 20 parts by mass, per 100 parts by mass of the polyether copolymer.

[0040] The active energy rays used to crosslink the polyether copolymer used in the present invention may be ultraviolet light, visible light, electron beams, etc. Among these, ultraviolet light is particularly preferred in view of the cost of the equipment and ease of control.

[0041] The method for producing the polymer electrolyte composite material is not particularly limited, and a general method can be used. Dispersion can be carried out using a stirrer, disperser, kneader, planetary ball mill, homogenizer, etc. To improve the efficiency of dispersion, the material may be heated within a range that does not affect the material.

[0042] <Composition for electrode mixture layer of lithium ion secondary battery> The composition for an electrode mixture layer of a lithium ion secondary battery of the present invention (also simply referred to as an electrode mixture layer composition) contains at least an active material and an inorganic solid electrolyte, and is configured as a composition for a negative electrode mixture layer of a lithium ion secondary battery when a negative electrode active material is used, or as a composition for a positive electrode mixture layer of a lithium ion secondary battery when a positive electrode active material is used, and is characterized in that the polymer electrolyte composite material of the present invention is contained in one or both of the components.

[0043] <Composition for negative electrode mixture layer of lithium ion secondary battery> The composition for a negative electrode mixture layer of a lithium ion secondary battery (also simply referred to as a composition for a negative electrode mixture layer) contains at least a negative electrode active material and an inorganic solid electrolyte.

[0044] negative electrode active material The negative electrode active material used in the present invention may be a carbon material (natural graphite, artificial graphite, amorphous carbon, etc.) or a silicon-based compound having a structure (porous structure) capable of absorbing and desorbing lithium ions. The particle size is preferably 10 nm or more and 100 μm or less, more preferably 20 nm or more and 20 μm or less. In addition, when a lithium ion secondary battery utilizing the dissolution and precipitation of lithium is produced, metallic lithium or a lithium alloy capable of absorbing and desorbing lithium may be used.

[0045] Examples of carbon materials include graphite, low-crystalline carbon (soft carbon, hard carbon), carbon black (ketjen black, acetylene black, channel black, lamp black, oil furnace black, thermal black, etc.), fullerene, carbon nanotube, carbon nanofiber, carbon nanohorn, carbon fibril, coke, mesocarbon microbeads (MCMB), mesophase pitch-based carbon fiber, phenolic resin baked body, polyacrylonitrile-based carbon fiber, etc., with graphite being preferred. These may be used alone or in combination of two or more types.

[0046] Examples of silicon-based compounds include Si element, alloys with Si, oxides containing Si, carbides containing Si, etc., such as Si, SiB4, SiB6, Mg2Si, Ni2Si, TiSi2, MoSi2, CoSi2, NiSi2, CaSi2, CrSi2, Cu5Si, FeSi2, MnSi2, NbSi2, TaSi2, VSi2, WSi2, ZnSi2, SiC, Si3N4, Si2N2O, SiO x (0 < x ≤ 2), SnSiO x , LiSiO can be exemplified, and it is preferable that the Si element, SiC, SiO x (0 < x ≤ 2), and the Si element and SiC are more preferable. These may be used alone or in combination of two or more.

[0047] When a carbon material or a silicon-based compound is used as the negative electrode active material, it may be composed of each alone or in combination of two or more. When a carbon material and a silicon-based compound are used in combination, it is preferable to contain them as follows.

[0048] The content of the carbon material with respect to the total amount of the negative electrode active material (100% by mass) is preferably at least 20% by mass, more preferably at least 40% by mass, particularly preferably at least 60% by mass, and may be up to 99% by mass, more preferably up to 98% by mass, and particularly preferably up to 96% by mass.

[0049] [[ID=…]] The content of the silicon-based compound with respect to the total amount of the negative electrode active material (100% by mass) is preferably at least 1% by mass, more preferably at least 2% by mass, particularly preferably at least 4% by mass, and preferably up to 80% by mass, more preferably up to 60% by mass, particularly preferably up to 50% by mass, and may be up to 30% by mass.

[0050] Examples of lithium alloys include lithium-aluminum alloys, lithium-tin alloys, lithium-indium alloys, lithium-silver alloys, lithium-gold alloys, lithium-zinc alloys, lithium-germanium alloys, lithium-silicon alloys, etc. Any other alloy that can be alloyed with lithium using a known alloying method can also be used.

[0051] The amount of the negative electrode active material in 100 parts by mass of all constituent materials of the composition for the negative electrode composite layer is preferably 30 parts by mass or more, more preferably 35 parts by mass or more, and even more preferably 40 parts by mass or more, as a lower limit, and preferably 90 parts by mass or less, preferably 80 parts by mass or less, and even more preferably 70 parts by mass or less, as an upper limit.

[0052] Inorganic solid electrolyte The inorganic solid electrolyte can be the inorganic solid electrolyte described below, and may be the same as or different from that which forms the inorganic solid electrolyte layer, but it is preferable to use the same inorganic solid electrolyte as that which forms the inorganic solid electrolyte layer.

[0053] The amount of inorganic solid electrolyte in 100 parts by mass of all constituent materials of the negative electrode mixture layer composition is preferably 15 parts by mass or more, more preferably 20 parts by mass or more, and even more preferably 25 parts by mass or more, as a lower limit, and preferably 50 parts by mass or less, preferably 45 parts by mass or less, and even more preferably 40 parts by mass or less, as an upper limit.

[0054] Furthermore, in the composition for the negative electrode mixture layer, it is preferable to use the polymer electrolyte composite material of the present invention as a filler for gaps that occur in the negative electrode mixture layer due to electrochemical and physical phenomena.

[0055] The amount of the polymer electrolyte composite material in the negative electrode mixture layer composition, relative to 100 parts by mass of all constituent materials, is preferably at least 0.1 parts by mass, more preferably at least 0.5 parts by mass, and even more preferably at least 1 part by mass. The upper limit is preferably at most 15 parts by mass, more preferably at most 10 parts by mass, and even more preferably at most 8 parts by mass. By being within these ranges, the polymer electrolyte composite material can sufficiently penetrate into gaps formed in the negative electrode mixture layer.

[0056] In addition to the above, a conductive additive or a binder may be used as long as it does not impair the effects of the present invention.

[0057] When a conductive additive is used, a known conductive additive can be used, and examples thereof include conductive carbon black such as graphite, furnace black, acetylene black, and ketjen black, carbon fibers such as carbon nanotubes (CNT), and metal powders. These conductive additives may be used alone or in combination of two or more.

[0058] When a conductive additive is used, the content of the conductive additive is not particularly limited, but is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, relative to 100 parts by mass of the negative electrode active material. The lower limit of the content of the conductive additive is typically 0.05 parts by mass or more, 0.1 parts by mass or more, 0.2 parts by mass or more, or 0.5 parts by mass or more, for example.

[0059] Known binders can be used, including fluorine-based resins such as polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, perfluoromethyl vinyl ether-tetrafluoroethylene copolymer, polytetrafluoroethylene, and fluororubber, hydrocarbon elastomers such as styrene-butadiene copolymer and ethylene-propylene copolymer, polysaccharides such as carboxymethyl cellulose, alginic acid, and sodium alginate, and polyimides.

[0060] The amount of binder mixed in 100% by mass of all constituent materials of the negative electrode mixture layer composition is preferably 0 to 20% by mass, more preferably 0 to 10% by mass, even more preferably 0 to 5% by mass, and particularly preferably 0 to 2% by mass.

[0061] The method for dispersing all the constituent materials is not particularly limited, and a general method can be used. Dispersion can be carried out using a stirrer, disperser, kneader, planetary ball mill, homogenizer, etc. To increase the efficiency of dispersion, heating may be performed within a range that does not affect the materials.

[0062] <Composition for Lithium-ion Secondary Battery Positive Electrode Mixture Layer> The composition for a positive electrode mixture layer of a lithium ion secondary battery (also simply referred to as a composition for a positive electrode mixture layer) contains at least a positive electrode active material and an inorganic solid electrolyte.

[0063] positive electrode active material The positive electrode active material used in the solid-state battery of the present invention is an alkali metal-containing composite oxide having one of the following compositions: AMO2, AM2O4, A2MO3, or AMBO4. A is an alkali metal, and M is a single or two or more transition metals, some of which may contain non-transition metals. B is P, Si, or a mixture thereof. The positive electrode active material is preferably a powder, with a particle size of preferably 50 microns or less, more preferably 20 microns or less. These positive electrode active materials have an electromotive force of 3 V (vs. Li / Li+) or more.

[0064] Preferred examples of the positive electrode active material used in the solid-state battery include LixCoO2, LixNiO2, LixMnO2, LixCrO2, LixFeO2, and LixCoaMn 1-a O2, LixCoaNi 1-a O2, LixCoaCr 1-a O2, LixCoaFE -a O2, LixCoaTi 1-a O2, LixMnaNi 1-a O2, LixMnaCr 1-a O2, LixMnaFE -a O2, LixMnaTi<h2 style=";text-align:left;direction:ltr"> 1-a <h2 style=";text-align:left;direction:ltr"> O2, LixNiaCr<h2 style=";text-align:left;direction:ltr"> 1-a <h2 style=";text-align:left;direction:ltr"> O2, LixNiaFE<h2 style=";text-align:left;direction:ltr"> -a <h2 style=";text-align:left;direction:ltr"> O2, LixNiaTi<h2 style=";text-align:left;direction:ltr"> 1-a <h2 style=";text-align:left;direction:ltr"> O2, LixCraFE<h2 style=";text-align:left;direction:ltr"> -a <h2 style=";text-align:left;direction:ltr"> O2, LixCraTi<h2 style=";text-align:left;direction:ltr"> 1-a <h2 style=";text-align:left;direction:ltr"> O2, LixFeaTi<h2 style=";text-align:left;direction:ltr"> 1-a <h2 style=";text-align:left;direction:ltr"> O2, LixCobMncNi<h2 style=";text-align:left;direction:ltr"> 1-b-C <h2 style=";text-align:left;direction:ltr"> O2, LixNiaCobAlcO2, LixCrbMncNi<h2 style=";text-align:left;direction:ltr"> 1-b-C <h2 style=";text-align:left;direction:ltr"> O2, LixFebMncNi<h2 style=";text-align:left;direction:ltr"> 1-b-C <h2 style=";text-align:left;direction:ltr"> O2, LixTibMncNi<h2 style=";text-align:left;direction:ltr"> 1-b-C <h2 style=";text-align:left;direction:ltr"> O2, LixMn2O4, LixMndCo<h2 style=";text-align:left;direction:ltr"> 2-d <h2 style=";text-align:left;direction:ltr"> O4, LixMndNi<h2 style=";text-align:left;direction:ltr"> 2-d <h2 style=";text-align:left;direction:ltr"> O4, LixMndCr<h2 style=";text-align:left;direction:ltr"> 2-d <h2 style=";text-align:left;direction:ltr"> O4, LixMndFe<h2 style=";text-align:left;direction:ltr"> 2-d <h2 style=";text-align:left;direction:ltr"> O4, LixMndTi<h2 style=";text-align:left;direction:ltr"> 2-d <h2 style=";text-align:left;direction:ltr"> O4, LiyMnO3, LiyMneCo<h2 style=";text-align:left;direction:ltr"> 1-e <h2 style=";text-align:left;direction:ltr"> O3, LiyMneNi<h2 style=";text-align:left;direction:ltr"> 1-e <h2 style=";text-align:left;direction:ltr"> O3, LiyMneFE<h2 style=";text-align:left;direction:ltr"> -e <h2 style=";text-align:left;direction:ltr"> O3, LiyMneTi<h2 style=";text-align:left;direction:ltr"> 1-e <h2 style=";text-align:left;direction:ltr"> O3, LixCoPO4, LixMnPO4, LixNiPO4, LixFePO4, LixCofMn<h2 style=";text-align:left;direction:ltr"> 1-f <h2 style=";text-align:left;direction:ltr"> PO4, LixCofNi<h2 style=";text-align:left;direction:ltr"> 1-f <h2 style=";text-align:left;direction:ltr"> PO4, LixCofFE<h2 style=";text-align:left;direction:ltr"> -f <h2 style=";text-align:left;direction:ltr"> PO4, LixMnfNi<h2 style=";text-align:left;direction:ltr"> 1-f <h2 style=";text-align:left;direction:ltr"> PO4, LixMnfFE<h2 style=";text-align:left;direction:ltr"> -f <h2 style=";text-align:left;direction:ltr"> PO4, LixNifFE<h2 style=";text-align:left;direction:ltr"> -f <h2 style=";text-align:left;direction:ltr"> PO4,LiyCoSiO4, LiyMnSiO4, LiyNiSiO4, LiyFeSiO4, LiyCogMn<h2 style=";text-align:left;direction:ltr"> 1-g <h2 style=";text-align:left;direction:ltr"> SiO4, LiyCogNi<h2 style=";text-align:left;direction:ltr"> 1-g <h2 style=";text-align:left;direction:ltr"> SiO4, LiyCogFE<h2 style=";text-align:left;direction:ltr"> -g <h2 style=";text-align:left;direction:ltr"> SiO4, LiyMngNi<h2 style=";text-align:left;direction:ltr"> 1-g <h2 style=";text-align:left;direction:ltr"> SiO4, LiyMngFE<h2 style=";text-align:left;direction:ltr"> -g <h2 style=";text-align:left;direction:ltr"> SiO4, LiyNigFE<h2 style=";text-align:left;direction:ltr"> -g <h2 style=";text-align:left;direction:ltr"> SiO4, LiyCoPhSi<h2 style=";text-align:left;direction:ltr"> 1-h <h2 style=";text-align:left;direction:ltr"> O4, LiyMnPhSi<h2 style=";text-align:left;direction:ltr"> 1-h <h2 style=";text-align:left;direction:ltr"> O4, LiyNiPhSi1-h O4, LiyFePhSi 1-h O4, LiyCogMn 1-g PhSi 1-h O4, LiyCogNi 1-g PhSi 1-h O4, LiyCogFE -g PhSi 1-h O4, LiyMngNi 1-g PhSi 1-h O4, LiyMngFE -g PhSi 1-h O4, LiyNigFE -g PhSi 1-h Examples of the lithium-containing composite oxides include O4 (where x = 0.01 to 1.2, y = 0.01 to 2.2, a = 0.01 to 0.99, b = 0.01 to 0.98, c = 0.01 to 0.98, and b + c = 0.02 to 0.99, d = 1.49 to 1.99, e = 0.01 to 0.99, f = 0.01 to 0.99, g = 0.01 to 0.99, and h = 0.01 to 0.99).

[0065] Among the above-mentioned preferred positive electrode active materials for use in solid-state batteries, more preferred positive electrode active materials are specifically LixCoO2, LixNiO2, LixMnO2, LixCrO2, and LixCoaNi 1-a O2, LixMnaNi 1-a O2, LixCobMncNi 1-b-C O2, LixNiaCobAlcO2, LixMn2O4, LiyMnO3, LiyMneFE -e O3, LiyMneTi 1-e O3, LixCoPO4, LixMnPO4, LixNiPO4, LixFePO4, LixMnfFE -f PO4 is an example. (Here, x = 0.01 to 1.2, y = 0.01 to 2.2, a = 0.01 to 0.99, b = 0.01 to 0.98, c = 0.01 to 0.98, and b + c = 0.02 to 0.99, d = 1.49 to 1.99, e = 0.01 to 0.99, and f = 0.01 to 0.99. Note that the values ​​of x and y increase or decrease with charge and discharge.)

[0066] The amount of the positive electrode active material in 100 parts by mass of all constituent materials of the positive electrode composite layer composition is preferably 30 parts by mass or more, more preferably 35 parts by mass or more, and even more preferably 40 parts by mass or more, as a lower limit, and preferably 90 parts by mass or less, preferably 80 parts by mass or less, and even more preferably 70 parts by mass or less, as an upper limit.

[0067] Inorganic solid electrolyte The inorganic solid electrolyte can be the inorganic solid electrolyte described below, and may be the same as or different from that which forms the inorganic solid electrolyte layer, but it is preferable to use the same inorganic solid electrolyte as that which forms the inorganic solid electrolyte layer.

[0068] The amount of inorganic solid electrolyte in 100 parts by mass of all constituent materials of the positive electrode composite layer composition is preferably 15 parts by mass or more, more preferably 20 parts by mass or more, and even more preferably 25 parts by mass or more, as a lower limit, and preferably 50 parts by mass or less, preferably 40 parts by mass or less, and even more preferably 40 parts by mass or less, as an upper limit.

[0069] Furthermore, it is preferable to use the polymer electrolyte composite material of the present invention in the positive electrode mixture layer as a filler for gaps that occur due to electrochemical and physical phenomena.

[0070] The amount of the polymer electrolyte composite material in 100 parts by mass of all constituent materials of the positive electrode mixture layer composition is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, and even more preferably 1 part by mass or more, as a lower limit. The upper limit is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 8 parts by mass or less. These ranges allow the polymer electrolyte composite material to sufficiently penetrate into gaps formed in the positive electrode mixture layer.

[0071] In addition to the above, a conductive additive or a binder may be used as long as it does not impair the effects of the present invention.

[0072] When a conductive additive is used, a known conductive additive can be used, and examples thereof include conductive carbon black such as graphite, furnace black, acetylene black, and ketjen black, carbon fibers such as carbon nanotubes (CNT), and metal powders. These conductive additives may be used alone or in combination of two or more.

[0073] When a conductive additive is used, the content of the conductive additive is not particularly limited, but is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, relative to 100 parts by mass of the positive electrode active material. The lower limit of the content of the conductive additive is typically 0.05 parts by mass or more, 0.1 parts by mass or more, 0.2 parts by mass or more, or 0.5 parts by mass or more, for example.

[0074] Known binders can be used, including fluorine-based resins such as polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, perfluoromethyl vinyl ether-tetrafluoroethylene copolymer, polytetrafluoroethylene, and fluororubber, hydrocarbon elastomers such as styrene-butadiene copolymer and ethylene-propylene copolymer, polysaccharides such as carboxymethyl cellulose, alginic acid, and sodium alginate, and polyimides.

[0075] The amount of binder mixed in 100% by mass of all constituent materials of the positive electrode mixture layer composition is preferably 0 to 20% by mass, more preferably 0 to 10% by mass, even more preferably 0 to 5% by mass, and particularly preferably 0 to 2% by mass.

[0076] The method for dispersing all the constituent materials is not particularly limited, and a general method can be used. Dispersion can be carried out using a stirrer, disperser, kneader, planetary ball mill, homogenizer, etc. To improve the efficiency of dispersion, heating may be performed within a range that does not affect the materials.

[0077] <Electrodes for lithium-ion secondary batteries> The lithium ion secondary battery electrode of the present invention is composed of at least a current collector and an electrode mixture layer composition. More specifically, in the case of a negative electrode for a lithium ion secondary battery, the electrode is composed of at least a negative electrode current collector and an electrode mixture layer composition, and in the case of a positive electrode for a lithium ion secondary battery, the electrode is composed of at least a positive electrode current collector and an electrode mixture layer composition.

[0078] <Anode for lithium-ion secondary batteries> As described above, the negative electrode for a lithium ion secondary battery of the present invention is composed of at least a negative electrode current collector and a composition for a negative electrode mixture layer.

[0079] Negative electrode current collector The negative electrode current collector used in the present invention may have a lithium metal layer formed on it by charging, and any current collector that does not react with lithium when the lithium metal layer is formed may be used, for example, metal, carbon, conductive polymer, etc., with metal being preferred. Metals typically used for the current collector include aluminum, platinum, nickel, tantalum, titanium, stainless steel, copper, and other alloys. Among these, metal foils such as copper foil are preferred in terms of conductivity and voltage resistance.

[0080] The thickness of the negative electrode current collector is not particularly limited, but may be, for example, about 5 to 50 μm, and preferably about 10 to 20 μm.

[0081] Method for manufacturing negative electrode for lithium ion secondary battery The method for producing the negative electrode for a lithium ion secondary battery of the present invention is not particularly limited, and a general method can be used. For example, a method in which a composition for a negative electrode composite layer is applied to a negative electrode current collector, the composition is molded to produce a negative electrode composite layer, and the layers are integrated by press molding or the like, or a method in which a negative electrode composite layer is previously produced, the layer is bonded to a negative electrode current collector, and the layers are then integrated by press molding or the like can be used.

[0082] The negative electrode composite layer can be produced, for example, by a wet method in which a slurry solution prepared by dispersing a composition for a negative electrode composite layer in a solvent or the like is uniformly applied to an appropriate thickness on a negative electrode current collector, a release film, or the like by a doctor blade method, an applicator method, a silk screen method, or the like, and then dried; or by a dry method in which the composition for a negative electrode composite layer is placed in a mold or the like and then subjected to press molding or the like.

[0083] The negative electrode mixture layer and the negative electrode current collector prepared by any of the above methods are molded and integrated by a press or the like to produce a negative electrode for a lithium ion secondary battery.

[0084] <Positive electrodes for lithium-ion secondary batteries> The positive electrode for a lithium ion secondary battery of the present invention is configured to include at least a positive electrode current collector and a positive electrode mixture layer.

[0085] positive electrode current collector The positive electrode current collector used in the present invention may be a known positive electrode current collector, specifically, a metal such as aluminum, nickel, stainless steel, gold, platinum, or titanium.

[0086] Method for manufacturing positive electrodes for lithium-ion secondary batteries The method for producing the positive electrode for a lithium ion secondary battery of the present invention is not particularly limited, and a general method can be used. For example, a method in which a composition for a positive electrode composite layer is applied to a positive electrode current collector, the composition is molded, a positive electrode composite layer is produced, and the layers are integrated by press molding or the like, or a method in which a positive electrode composite layer is produced in advance, the layer is bonded to a positive electrode current collector, and the layers are then integrated by press molding or the like, can be used.

[0087] The positive electrode composite layer can be produced, for example, by a wet method in which a slurry solution prepared by dispersing a composition for a positive electrode composite layer in a solvent or the like is uniformly applied to an appropriate thickness on a positive electrode current collector, a release film, or the like by a doctor blade method, an applicator method, a silk screen method, or the like, and then dried; or by a dry method in which the composition for a positive electrode composite layer is placed in a mold or the like, and a green compact is obtained by press molding or the like.

[0088] The positive electrode mixture layer and the positive electrode current collector prepared by any of the above methods are molded and integrated by a press or the like to produce a positive electrode for a lithium ion secondary battery.

[0089] <Lithium-ion secondary battery> The lithium ion secondary battery of the present invention is composed of an inorganic solid electrolyte layer and the above-mentioned lithium ion secondary battery electrode. Specifically, the inorganic solid electrolyte layer is sandwiched between the lithium ion secondary battery negative electrode and the lithium ion secondary battery positive electrode.

[0090] <Inorganic solid electrolyte layer> Examples of the inorganic solid electrolyte layer include an oxide solid electrolyte and a sulfide solid electrolyte. An inorganic solid electrolyte is generally an aggregate of inorganic solid particles that constitute the electrolyte.

[0091] oxide solid electrolyte The oxide solid electrolyte is not particularly limited as long as it contains oxygen, has the ionic conductivity of a metal belonging to Group 1 or 2 of the periodic table, and has electronic insulation properties.

[0092] Specific compounds that make up the oxide solid electrolyte include La 2 / 3-x Li 3x Perovskite oxide solid electrolyte such as TiO3, Li 1+x Al x Ti 2-x NASICON-type crystalline oxide solid electrolytes such as (PO4)3, Li7La3Zr2O 12 Garnet-type oxide solid electrolytes such as Li 14 ZnGeO 16 LISICON-type oxide solid electrolytes such as Li3PO4-Li4SiO4, 50Li4SiO4·50Li3BO3 and other oxide glasses, Li 1.07 Al 0.69 Ti 1.46 (PO4)3, Li 1.5 Al 0.5 Ge 1.5 Oxide crystallized glass such as (PO4)3, Li7La3Zr2O12 Examples of halide-based solid electrolytes include LiAlCl4, Li3InBr6, LiF, LiCl, LiBr, and LiI. These may be used alone or in combination of two or more.

[0093] Sulfide solid electrolyte The sulfide solid electrolyte is not particularly limited as long as it contains sulfur, has the ionic conductivity of a metal belonging to Group 1 or 2 of the periodic table, and has electronic insulation properties.

[0094] The sulfide-based solid electrolyte may be a glass-based sulfide solid electrolyte or a glass-ceramic-based sulfide solid electrolyte. These may be used alone or in combination of two or more. The glass-based sulfide solid electrolyte can be obtained by vitrifying raw materials. The glass-ceramic-based sulfide solid electrolyte can be obtained, for example, by heat-treating a glass-based sulfide solid electrolyte. In addition, the sulfide-based solid electrolyte preferably has a crystalline structure. Examples of the crystalline structure include a Thio-LISICON-type crystalline structure, an LGPS-type crystalline structure, and an Argyrodite-type crystalline structure.

[0095] Examples of sulfide solid electrolytes having a crystalline structure include Li7P3S 11 , Li 10 GeP2S 12 , Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 , Li 9.42 Si 1.02 P 2.1 S 9.96 O 2.24 LGPS-type sulfide solid electrolytes such as Li6PS5Cl, Li 6.6 Ge 0.6 P 0.4 S5I, Li7Ge3PS 12 Argyrodite-type sulfide solid electrolytes such as Li 4.275 Ge 0.61 Ga 0.25Examples of suitable sulfide solid electrolytes include Thio-LISICON-type sulfide solid electrolytes such as LiSnS4, Li4SnS4, and β-Li3PS4. Among these, argyrodite-type sulfide solid electrolytes and Thio-LISICON-type sulfide solid electrolytes are preferred, with argyrodite-type sulfide solid electrolytes being more preferred. These may be used alone or in combination of two or more.

[0096] The sulfide-based solid electrolyte is preferably a sulfide solid electrolyte having high ionic conductivity from the viewpoint of improving the electrical characteristics of the lithium ion secondary battery. Specific examples of the ionic conductivity include sulfide solid electrolytes having a conductivity of 1×10 -4 S / cm or more is preferable, and 1×10 -3 It is more preferable that the viscosity is S / cm or more.

[0097] When the inorganic solid electrolyte is in the form of particles, the particle size is, for example, 0.01 to 100 μm, and preferably 0.1 to 20 μm.

[0098] For the purpose of improving the binding strength between the inorganic solid particles, a binder may be contained, and a known binder can be used. Specifically, fluororesin binders such as polyvinylidene fluoride, vinylidene fluoride-hexafluoropropylene copolymer, perfluoromethyl vinyl ether-tetrafluoroethylene copolymer, and polytetrafluoroethylene, rubber binders such as fluororubber, styrene-butadiene rubber, and ethylene-propylene rubber, polysaccharides such as carboxymethyl cellulose, alginic acid, and sodium alginate, and polyimides can be used.

[0099] Method for manufacturing inorganic solid electrolyte layer The inorganic solid electrolyte layer can be produced by any conventional method without any particular limitation. It can be obtained by preparing pellets of inorganic solid particles and then molding them into a desired shape using a press molding machine or the like. Alternatively, it can be produced by dispersing inorganic solid particles in an organic solvent or the like, and uniformly applying a slurry solution to an appropriate thickness using a doctor blade method, an applicator method, a silk screen method, or the like.

[0100] The organic solvent used to prepare the slurry solution is preferably one that does not react with the inorganic solid electrolyte. Specific examples thereof include butyl butyrate, toluene, ortho-xylene, tetralin, Examples include acetonitrile, isobutyronitrile, anisole, methyl isobutyl ketone, and diisobutyl ketone.

[0101] The solid content concentration in the slurry is preferably 10 to 90 mass %, more preferably 20 to 85 mass %, and particularly preferably 20 to 80 mass %.

[0102] The preparation method is not particularly limited, and the binder, conductive additive, water, etc. may be dispersed using a conventional stirrer, disperser, kneader, planetary ball mill, homogenizer, etc. To increase the efficiency of dispersion, the material may be heated within a range that does not affect the material.

[0103] Lithium-ion secondary battery manufacturing method The method for producing the lithium ion secondary battery of the present invention is not particularly limited, and the battery is produced by a known method using a positive electrode for a lithium ion secondary battery, a negative electrode for a lithium ion secondary battery, and an inorganic solid electrolyte layer. For example, in the case of a coin-type battery, the positive electrode for a lithium ion secondary battery, the inorganic solid electrolyte layer, and the negative electrode for a lithium ion secondary battery are formed in this order on an outer can, stacked, and then pressed together under high confining pressure to obtain a lithium ion secondary battery. The shape of the lithium ion secondary battery is not limited, and examples include a coin type, a cylindrical type, and a sheet type. [Example]

[0104] The present invention will be described in more detail in the following examples, but the present invention is not limited to these examples.

[0105] [Synthesis Example] (Production of Polymerization Catalyst) A three-neck flask equipped with a stirrer, a thermometer, and a distillation apparatus was charged with 10 parts by mass of tributyltin chloride and 35 parts by mass of tributylphosphate, and the mixture was heated at 250°C for 20 minutes with stirring under a nitrogen stream to remove the distillate, thereby obtaining a solid condensation product as a residue. This was used as a polymerization catalyst in the following polymerization examples.

[0106] [Polymerization Example 1] (Production of Polyether Copolymer 1) The interior of a 3 L four-neck glass flask was purged with nitrogen, and 3.3 parts by weight of the polymerization catalyst used in the synthesis examples, 56 parts by weight of ethylene oxide (adjusted to a moisture content of 10 ppm or less), 179 parts by weight of propylene oxide, 18 parts by weight of allyl glycidyl ether, 0.4 parts by weight of tert-butanol, and 1,000 parts by weight of n-hexane as a solvent were charged. While monitoring the conversion rate by gas chromatography, 80 parts by weight of ethylene oxide was gradually added. The polymerization temperature was 20°C, and the reaction was carried out for 10 hours. The polymerization reaction was terminated by the addition of methanol. Polyether copolymer 1 was removed by decantation and then dried at 25°C under normal pressure for 24 hours, and then at 40°C under reduced pressure for 10 hours, yielding 317 parts by weight of polyether copolymer 1. The resulting polyether copolymer 1 was subjected to the following tests, and the results are shown in Table 1.

[0107] [Weight average molecular weight of polyether copolymer] Gel permeation chromatography (GPC) was performed to calculate the weight-average molecular weight in terms of standard polystyrene. GPC measurements were performed at 60°C using Shimadzu RID-6A, Showa Denko Showdex KD-807, KD-806, KD-806M, and KD-803 columns, and DMF as the solvent.

[0108] [Copolymer composition of polyether copolymer] The polyether copolymer was dissolved in deuterated chloroform, and the integral value of each unit was determined by 1H-NMR, and the composition ratio was calculated from the calculated results. The apparatus used was a JNM ECZS-400 model manufactured by JEOL Ltd.

[0109] [Evaluation of degradation of sulfide solid electrolytes] Polyether copolymer 1 was dissolved in toluene to a solids concentration of 10% by mass to prepare polyether solution 1. 10 parts by mass of polyether solution 1 and 4 parts by mass of argyrodite-type sulfide solid electrolyte (Li6PS5Cl manufactured by NEI) were mixed so that the mass ratio of polyether copolymer 1 to argyrodite-type sulfide solid electrolyte (Polyether copolymer 1:Argyrodite-type sulfide solid electrolyte) was 1:4. The toluene was then removed by vacuum heating and drying to prepare a composite of the polyether copolymer and sulfide solid electrolyte. This composite was then heat-treated at 60°C for one week. The results were then analyzed using a nuclear magnetic resonance (NMR) spectrometer. 31 P-NMR tests were carried out.

[0110] 31 P-NMR testing In a glove box under an argon atmosphere, the composite after the heat treatment was ground in a mortar and mixed thoroughly, then sealed in a solid-state NMR sample tube (probe diameter: 4.0 mm) and measured using the single pulse method in an NMR device (device name: Agilent NMR System 400WB). NMR measurements were also performed on the composite before the heat treatment using the same procedure. The evaluation method consisted of measuring the PS4 contained in the sulfide solid electrolyte before and after the heat treatment. 3- The spectra of the units and P2S7 produced by reaction with polyether copolymers 4- The spectral changes due to the unit were evaluated. The test temperature was 25°C. An 85% aqueous solution of phosphoric acid was used as the reference substance showing a chemical shift of 0 ppm. Sample rotation speed: 20kHz Measurement accumulation count: 16 times Relaxation time: 2000 seconds

[0111] [Polymerization Example 2] (Production of Polyether Copolymer 2) The inside of a 3 L glass four-neck flask was purged with nitrogen, and 1 part by mass of the condensation product shown in the catalyst synthesis example as a polymerization catalyst and a glycidyl ether compound (a) adjusted to a water content of 10 ppm or less were added: [ka] 150 parts by mass of ethanol and 1,000 parts by mass of n-hexane as a solvent were charged, and 150 parts by mass of ethylene oxide and 30 parts by mass of allyl glycidyl ether were added sequentially while monitoring the polymerization rate of compound (a) by gas chromatography. The polymerization temperature was 20°C, and the reaction was carried out for 10 hours. The polymerization reaction was terminated by adding 1 mL of methanol. The polyether copolymer was removed by decantation and then dried at 40°C under normal pressure for 24 hours and then at 45°C under reduced pressure for 10 hours to obtain 280 parts by mass of polyether copolymer 2. The resulting polyether copolymer 2 was evaluated as described above, and the results are shown in Table 1.

[0112] [Table 1]

[0113] [Example 1] 100 parts by weight of the polyether copolymer 1 obtained in Polymerization Example 1, 78 parts by weight of LiN(FSO2)2 as a lithium salt compound, and 100 parts by weight of propylene carbonate as a cyclic carbonate compound were stirred and mixed in a mortar to produce a polymer electrolyte composite material 1. Next, 278 parts by weight of the polymer electrolyte composite material 1, 2440 parts by weight of a Si active material (negative electrode active material, manufactured by Elkem, average particle size 3 μm), 1240 parts by weight of an argyrodite-type sulfide solid electrolyte (inorganic solid electrolyte, manufactured by NEI, Li6PS5Cl), and 320 parts by weight of acetylene black as a conductive additive were stirred and mixed in a mortar, and then applied to a PET film and air-dried at room temperature for 24 hours to produce a negative electrode composite layer composition 1. The resulting polymer electrolyte composite material 1 and negative electrode composite layer composition 1 were evaluated as follows, and the results are shown in Table 2.

[0114] [Evaluation of ionic conductivity in polymer electrolyte composites] Polymer electrolyte composite material 1 was applied to a SUS spacer to a predetermined thickness and dried to prepare a polyether electrolyte membrane (thickness of electrolyte membrane: 100 μm). Next, a SUS spacer was attached to the counter electrode to prepare a SUS blocking cell, and an AC impedance test was performed using a potentio / galvanostat device.

[0115] [AC impedance test] A SUS blocking cell for polyether electrolyte was fabricated, and an AC impedance test was performed using a potentio / galvanostat device (device name: SP-300 manufactured by BioLogic). The resistance (Ω) of the composite material was calculated from the diameter of the semicircular arc in the real axis direction obtained from the Cole-Cole plot. The ionic conductivity of the cell was calculated using the following formula from the thickness and surface area of ​​the cell. The test temperature was set to 25°C. Measurements were performed at a voltage amplitude of 20 mV and a measurement frequency range of 7 MHz to 1 Hz. The ionic conductivity (9.34 x 10) of the argyrodite-type sulfide solid electrolyte (Li6PS5Cl) was also used as an evaluation index. -4 S / cm), and a rating of ○ or × was also given. If the ionic conductivity was equal to or greater than that of the argyrodite-type sulfide solid electrolyte, it was given a rating of ○, and if the ionic conductivity was less than that of the argyrodite-type sulfide solid electrolyte, it was given a rating of ×. When the ionic conductivity is equal to or greater than that of the argyrodite-type sulfide solid electrolyte, the conductive path of the lithium ions is connected smoothly, resulting in little loss of electrical properties. On the other hand, when the ionic conductivity is low, the conductive path of the lithium ions avoids the polymer electrolyte composite material, preventing a smooth conductive path, resulting in greater loss of electrical properties. σ=1 / R×(d / A) σ: Ionic conductivity of the composite material (S / cm) R: Resistance of the composite material (Ω) d: Thickness of composite material (cm) A: Surface area of ​​the composite material (cm 2 )

[0116] [Fabrication of lithium-ion secondary batteries and battery assembly evaluation] A SUS electrode was placed inside a ceramic cylinder (opening diameter 10 mm), and 80 mg of sulfide solid electrolyte was placed on top of it. The electrodes were then sandwiched between other SUS electrodes and uniaxially pressed at 31 MPa to produce a solid electrolyte layer. The electrodes were then removed, and 6.3 mg of the above-mentioned negative electrode composite layer composition 1 was placed on the solid electrolyte layer. The electrodes were then sandwiched again between the SUS electrodes and uniaxially pressed at 248 MPa to form a negative electrode for a lithium-ion secondary battery, which was then pressed onto the solid electrolyte layer. The SUS electrode on the electrolyte layer side was then removed, and an indium-lithium alloy foil was inserted. The cells were then uniaxially pressed at 91 MPa to press the indium-lithium alloy foil and the solid electrolyte layer together. The lower electrode was then reattached, and the upper and lower electrodes were crimped together at a torque of 5 N m to constrain the cell, producing a capacity of 7.6 mAh / cm. 2 Lithium ion secondary batteries 1 equivalent to the above were fabricated. The fabrication of the lithium ion secondary batteries was carried out in a glove box purged with argon at an average dew point of -80°C. The presence or absence of leakage during uniaxial press molding was evaluated as an assembly evaluation, with batteries that did not leak being rated as ○ and batteries that leaked being rated ×.

[0117] [Initial charge / discharge test and cycle test (measurement of cycle capacity retention)] The fabricated lithium-ion secondary battery 1 was subjected to a charge / discharge test using a charge / discharge evaluation device: TOSCAT-3100 (Toyo Systems Co., Ltd.). First, in the initial charge / discharge test, constant current charging at 0.1 C and constant voltage charging (end current: 0.02 C) were applied, and the battery was held at -0.62 V. After resting the battery for 10 minutes, it was discharged to 1.38 V by constant current discharging at 0.1 C. After the initial charge / discharge test, a cycle test was performed, in which constant current charging at 0.5 C and constant voltage charging (end current: 0.02 C) were applied, and the battery was held at -0.62 V. After resting the battery for 10 minutes, it was discharged to 1.38 V by constant current discharging at 0.5 C. This cycle constituted one cycle, and 25 charge / discharge cycles were performed. The discharge capacity at the 25th cycle was divided by the discharge capacity at the first cycle to obtain a percentage, which was used as the cycle capacity retention rate (%).

[0118] [Comparative Examples 1 to 3] A polymer electrolyte composite material and a composition for a negative electrode mixture layer were obtained in the same manner as in Example 1, except that the compositions were changed as shown in Table 1. The above-mentioned evaluations were carried out using the obtained polymer electrolyte composite material and composition for a negative electrode mixture layer. The results are shown in Table 2.

[0119] [Table 2]

[0120] It is presumed that Example 1, which used the polymer electrolyte composite material of the present invention, had high stability with respect to the sulfide solid electrolyte and also had equivalent ionic conductivity, and therefore achieved a higher charge / discharge capacity retention rate in the cycle test than Comparative Examples 1 to 3. Although the propylene carbonate used in Comparative Example 3 had high stability with respect to the sulfide solid electrolyte and high ionic conductivity, it was in a liquid state, and therefore leakage occurred during battery assembly. On the other hand, the reason why no leakage occurred in Example 1 despite the use of propylene carbonate is thought to be that the polyether copolymer has a liquid-retaining ability, and the polyether copolymer embraces the propylene carbonate, preventing leakage. [Industrial Applicability]

[0121] The solid electrolyte secondary battery of the present invention, which contains the polyether electrolyte, an inorganic solid electrolyte, and metallic lithium, has excellent energy density and can be suitably used for in-vehicle applications such as electric vehicles and hybrid electric vehicles, and for large-scale battery applications such as storage batteries for home power storage.

Claims

1. A polymer electrolyte composite material comprising at least a polyether copolymer containing at least a structural unit (A) derived from ethylene oxide represented by the following formula (1) and a structural unit (B) derived from an epoxy compound represented by the following formula (2), a cyclic carbonate compound represented by the following formula (4), and a lithium salt: The polymer electrolyte composite material has a polymerization composition in which the structural unit (A) accounts for 1 to 79 mol % and the structural unit (B) accounts for 20 to 98 mol % of 100 mol % of the polyether copolymer. 【Chemical 1】 （１） 【Chemistry 2】 （２） [In the formula, R １ is an alkyl group, a cycloalkyl group, or an aryl group having 1 to 12 carbon atoms. 【Chemistry 3】 （４） [In the formula, R 3 is a linear or branched alkyl group having 1 to 8 carbon atoms.

2. The polyether copolymer according to claim 1, further comprising, as a polymerization composition thereof, a structural unit (C) derived from a compound having an ethylenically unsaturated group represented by the following formula (3), wherein the structural unit (C) accounts for 0.1 to 20 mol % of 100 mol % of the polyether copolymer: 【Chemistry 4】 （３） [In the formula, R ２ is a group having an ethylenically unsaturated group.

3. 2. The polymer electrolyte composite material according to claim 1, comprising at least 4 parts by mass to 70 parts by mass of a polyether copolymer, 4 parts by mass to 90 parts by mass of a cyclic carbonate compound represented by formula (4), and 2 parts by mass to 90 parts by mass of a lithium salt compound, relative to 100 parts by mass of the polymer electrolyte composite material.

4. A composition for an electrode mixture layer of a lithium ion secondary battery, comprising at least the polymer electrolyte composite material according to claim 1, an active material, and an inorganic solid electrolyte.

5. An electrode mixture layer for a lithium ion secondary battery, produced using the composition for a lithium ion secondary battery electrode mixture layer according to claim 4.

6. An electrode for a lithium ion secondary battery, produced using the electrode mixture layer for a lithium ion secondary battery according to claim 5.

7. A lithium ion secondary battery produced using the electrode for a lithium ion secondary battery according to claim 6.

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