Composite solid electrolyte

Abstract

To provide a composite solid electrolyte that prevents the occurrence of cracks.SOLUTION: The inventors have found out that a composite solid electrolyte including a polyether copolymer having a constitutional unit derived from ethylene oxide and an inorganic solid electrolyte, and in which in Young' modulus measurement by a nanoindentation method, the ratio between the minimum value of the Young's modulus (EMIN) and the Young's modulus at an indentation depth of 10000 nm (E10000) (E10000 / EMIN) is 1.10-2.50, is a composite solid electrolyte having sufficient durability and flexibility against external pressure and excellent in cycle characteristics.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a composite solid electrolyte for all-solid-state batteries.

Background Art

[0002] Secondary batteries are used in various forms, large and small, in all industries. In the currently most popular liquid lithium-ion secondary batteries, in mobile phones and the like, high performance has been achieved through miniaturization and weight reduction, but there are problems such as a decrease in energy density and a decrease in capacity due to repeated charge and discharge. In addition, in large liquid lithium-ion secondary batteries mounted on hybrid vehicles and the like, there remains a risk of fire due to electrolyte leakage. In recent years, in order to solve these problems, the development of materials for all-solid-state lithium-ion secondary batteries has been actively carried out.

[0003] Since all-solid-state lithium-ion secondary batteries do not use an electrolyte solution, there is no concern about liquid leakage. On the other hand, there has been a problem that cracks are generated in the solid electrolyte due to external pressure during press molding or the like in battery manufacturing.

[0004] In response to this problem, Patent Document 1 proposes a powdery sulfide-based inorganic solid electrolyte material having lithium-ion conductivity and containing Li, P, and S as constituent elements, and having an angle of repose measured at 25°C in an argon atmosphere of 57° or more and 70° or less. It is said that this sulfide-based inorganic solid electrolyte material can suppress crack generation.

[0005] Further, in Patent Document 2, by setting stabilized zirconia having ion conductivity to 9.8% by volume or more and 24.0% by volume or less in 100% by volume of the solid electrolyte layer, it is possible to provide a solid electrolyte layer capable of suppressing the occurrence of cracks when an external force is applied and an all-solid-state battery using the same.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] According to the studies by the present inventors, since the binding property between inorganic particles is low, it was clear that even if an inorganic solid electrolyte layer could be formed, cracks were an important problem to be solved.

[0008] The present invention has been made in view of the above circumstances, and provides a composite solid electrolyte in which the generation of cracks is suppressed. Specifically, it is a composite solid electrolyte containing at least an inorganic solid electrolyte and a polyether copolymer, and an object thereof is to provide a composite solid electrolyte having sufficient durability and flexibility against external pressure and excellent cycle characteristics and the like.

Means for Solving the Problems

[0009] As a result of repeated studies to achieve the above object, the present inventors have found that a composite solid electrolyte containing a polyether copolymer having a structural unit derived from ethylene oxide and an inorganic solid electrolyte, and in the measurement of Young's modulus by the nanoindentation method, the ratio (E MIN ) of the minimum value of Young's modulus (E 10000 ) and the Young's modulus (E 10000 ) at a penetration depth of 10000 nm (E MIN ) within a specific range solves the above problems, and has completed the present invention. That is, the present invention relates to the following.

[0010] Item 1. Containing at least a polyether copolymer and an inorganic solid electrolyte, In the measurement of Young's modulus by the nanoindentation method (penetration depth 0 nm to 10000 nm), the minimum value of Young's modulus (E MIN) and the ratio (E 10000 ) to the Young's modulus (E 10000 / E MIN ) at a penetration depth of 10,000 nm is 1.10 to 2.50. A composite solid electrolyte. Item 2. The composite solid electrolyte according to Item 1, wherein 2 to 20 parts by mass of the polyether copolymer is contained per 100 parts by mass of the composite solid electrolyte. Item 3. The polyether copolymer is Formula (1):

Chemical formula

Chemical formula

Chemical formula

Advantages of the Invention

[0011] The composite solid electrolyte of the present invention has excellent physical properties against problems such as crack generation due to external pressure, which was a conventional problem, and is useful for realizing all-solid-state batteries with high energy density.

[0012] <Composite solid electrolyte> The composite solid electrolyte of the present invention contains at least a polyether copolymer and an inorganic solid electrolyte, and in the measurement of Young's modulus by the nanoindentation method (indentation depth: 0 nm to 10,000 nm), the minimum value of Young's modulus (E MIN ) and the Young's modulus (E 10000 ) at an indentation depth of 10,000 nm, the ratio (E 10000 / E MIN ) is 1.10 to 2.50.

[0013] Polyether copolymer The polyether copolymer used in the composite solid electrolyte of the present invention contains a polyether copolymer having a structural unit derived from ethylene oxide.

[0014] As the polyether copolymer having a structural unit derived from ethylene oxide, it is preferably a polyether copolymer containing 2 to 50 mol% of a structural unit derived from the following general formula (1), 40 to 97 mol% of a structural unit derived from the following formula (2), and 0.1 to 20 mol% of a structural unit derived from the following formula (3). The structural unit can also be described as a repeating unit. Formula (1):

Chemical formula

Chemical formula

Chemical formula

[0015] Here, the structural unit derived from the general formula (1) and the structural unit derived from the general formula (3) may each be derived from two or more different monomers.

[0016] The compound of the formula (1) can be easily synthesized by obtaining it from commercially available products or by a general ether synthesis method from epihalohydrin and alcohol. Examples of the aryl group include a phenyl group.

[0017] Examples of the compounds available from commercially available products include methyl glycidyl ether, ethyl glycidyl ether, butyl glycidyl ether, tert-butyl glycidyl ether, benzyl glycidyl ether, 2-ethylhexyl glycidyl ether, glycidyl phenyl ether, glycidyl isopropyl ether, etc. Among these commercially available products, methyl glycidyl ether, ethyl glycidyl ether, butyl glycidyl ether, and glycidyl isopropyl ether are preferred, and methyl glycidyl ether and ethyl glycidyl ether are particularly preferred.

[0018] In the monomer represented by the formula (1) obtained by synthesis, R 1 , R 2 , R 3 is hydrogen or -CH2O(CH2CH2O) n R 4 and R1 , R 2 , R 3 At least one of them is -CH2O(CH2CH2O) n R 4 is preferred. R 4 is preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 4 carbon atoms. n is preferably 0 to 6, more preferably 0 to 4, and even more preferably 0 to 2.

[0019] In 100 mol% of the polyether copolymer, as the structural unit derived from the general formula (1), the lower limit is preferably 2 mol% or more, more preferably 3 mol% or more, even more preferably 4 mol% or more, and particularly preferably 5 mol% or more. On the other hand, the upper limit is preferably 50 mol% or less, more preferably 45 mol% or less, even more preferably 40 mol% or less, and particularly preferably 35 mol% or less.

[0020] The compound of formula (2) is ethylene oxide, and commercially available products are easily available.

[0021] In 100 mol% of the polyether copolymer, as the structural unit derived from the general formula (2), the lower limit is preferably 40 mol% or more, more preferably 45 mol% or more, even more preferably 50 mol% or more. On the other hand, the upper limit is preferably 97 mol% or less, more preferably 95 mol% or less, even more preferably 90 mol% or less, and particularly preferably 85 mol% or less.

[0022] In the compound of formula (3), R 5is a substituent containing an ethylenically unsaturated group, and preferably has 2 to 6 carbon atoms. As the monomer component containing an ethylenically unsaturated group, 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, glycidyl-4-hexenoate are used. Preferably, they are allyl glycidyl ether, glycidyl acrylate, and glycidyl methacrylate.

[0023] In 100 mol% of the polyether copolymer, as the structural unit derived from the general formula (3), the lower limit is preferably 0.1 mol% or more, more preferably 0.5 mol% or more, and even more preferably 1.0 mol% or more. On the other hand, 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.

[0024] The molar ratio of the polymerization composition of the polyether copolymer is 1 The integral value of each unit can be obtained by 1H-NMR, and the composition can be determined from the calculation result.

[0025] The polyether copolymer may be either a block polymer or a random polymer. A random polymer is preferred because it has a greater effect of reducing the crystallinity of polyethylene oxide.

[0026] 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, still 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. Gel permeation chromatography (GPC) measurement was performed for the molecular weight measurement of the polyether copolymer, and the weight-average molecular weight was calculated by conversion to standard polystyrene. In addition, DMF (N,N-dimethylformamide) was used as the solvent.

[0027] The polyether copolymer can be synthesized as follows. Coordination anion initiators such as a catalyst system mainly composed of organoaluminum, a catalyst system mainly composed of organozinc, an organotin-phosphate ester condensate catalyst system, etc. as a ring-opening polymerization catalyst, or K as a counter ion + A polyether copolymer can be obtained by using an anion initiator such as potassium alkoxide containing, diphenylmethyl potassium, potassium hydroxide, etc., and reacting each monomer in the presence or absence of a solvent at a reaction temperature of 10 to 120 °C with stirring.

[0028] In 100 parts by mass of the composite solid electrolyte of the present invention, the content of the polyether copolymer is preferably 1 part by mass or more, more preferably 2 parts by mass or more, still more preferably 3 parts by mass or more, and particularly preferably 4 parts by mass or more as the lower limit. On the other hand, the upper limit is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, still more preferably 10 parts by mass or less, and particularly preferably 8 parts by mass or less. By being in these ranges, the composite solid electrolyte can be imparted with durability and elasticity against external pressure.

[0029] Inorganic solid electrolyte Examples of the inorganic solid electrolyte include oxide-based solid electrolytes and sulfide-based solid electrolytes. The inorganic solid electrolyte is generally an aggregate of inorganic solid particles constituting the electrolyte.

[0030] The oxide-based solid electrolyte is not particularly limited as long as it contains oxygen, has ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and has electron insulation properties.

[0031] Specific compounds constituting the oxide-based solid electrolyte include Li x La y TiO3 [x = 0.3 to 0.7, y = 0.3 to 0.7] (LLT), Li x La y Zr z M m O n (M is at least one element of Al, Mg, Ca, Sr, V, Nb, Ta, Ti, Ge, In, Sn, x satisfies 5 ≤ x ≤ 10, y satisfies 1 ≤ y ≤ 4, z satisfies 1 ≤ z ≤ 4, m satisfies 0 ≤ m ≤ 2, and n satisfies 5 ≤ n ≤ 20.) Li x B y M z O n (In the formula, M is at least one element of C, S, Al, Si, Ga, Ge, In, Sn, x satisfies 0 ≤ x ≤ 5, y satisfies 0 ≤ y ≤ 1, z satisfies 0 ≤ z ≤ 1, and n satisfies 0 ≤ n ≤ 6.) Li x (Al, Ga) y (Ti, Ge) z Si a P m O n (However, 1 ≤ x ≤ 3, 0 ≤ y ≤ 1, 0 ≤ z ≤ 2, 0 ≤ a ≤ 1, 1 ≤ m ≤ 7, 3 ≤ n ≤ 13), Li(3 - 2x)M x DO (x represents a number from 0 or more to 0.1 or less, M represents a divalent metal atom. D represents a halogen atom or a combination of two or more halogen atoms.) Li x Si y O z (1 ≤ x ≤ 5, 0 < y ≤ 3, 1 ≤ z ≤ 10), Li x S y O z (1 ≤ x ≤ 3, 0 < y ≤ 2, 1 ≤ z ≤ 10), Li3BO3 - Li2SO4, Li2O - B2O3 - P2O5, Li2O - SiO2, Li6BaLa2Ta2O 12 、Li3PO (4-3 / 2w) N w(where w < w<1), Li having a LISICON (Lithium super ionic conductor) type crystal structure 3.5 Zn 0.25 GeO4, La having a perovskite type crystal structure 0.55 Li 0.35 TiO3, LiTi2P3O having a NASICON (Natrium super ionic conductor) type crystal structure 12 Li (1+x+y) (Al, Ga) x (Ti, Ge) (2-x) Si y P (3-y) O 12 (where 0 ≤ x ≤ 1, 0 ≤ y ≤ 1), Li7La3Zr2O having a garnet type crystal structure 12 and the like. Also, phosphorus compounds containing Li, P, and O are desirable. For example, lithium phosphate (Li3PO4), LiPON in which part of the oxygen in lithium phosphate is substituted with nitrogen, LiPOD (D is at least one selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Nb, Mo, Ru, Ag, Ta, W, Pt, Au, etc.), and the like. Also, LiAON (A is at least one selected from Si, B, Ge, Al, C, Ga, etc.) can also be preferably used.

[0032] Among them, Li x La y TiO3 [x = 0.3 to 0.7, y = 0.3 to 0.7] (LLT), Li x La y Zr z M m O n (M is at least one element of Al, Mg, Ca, Sr, V, Nb, Ta, Ti, Ge, In, Sn, x satisfies 5 ≤ x ≤ 10, y satisfies 1 ≤ y ≤ 4, z satisfies 1 ≤ z ≤ 4, m satisfies 0 ≤ m ≤ 2, and n satisfies 5 ≤ n ≤ 20.), Li7La3Zr2O 12 (LLZ), Li3BO3, Li3BO3 - Li2SO4, Li3BO3 - Li2CO3, Li x (Al, Ga) y (Ti, Ge) z Sia P m O n (However, 1 ≦ x ≦ 3, 0 ≦ y ≦ 1, 0 ≦ z ≦ 2, 0 ≦ a ≦ 1, 1 ≦ m ≦ 7, 3 ≦ n ≦ 13) is preferable. These may be used alone or in combination of two or more kinds.

[0033] The sulfide-based solid electrolyte is not particularly limited as long as it contains sulfur, has ionic conductivity of a metal belonging to Group 1 or Group 2 of the periodic table, and has electron insulation. For example, a lithium ion conductive inorganic solid electrolyte satisfying the composition represented by the following formula can be mentioned.

[0034] Li a M b P c S d A e

[0035] In the formula, M represents an element selected from B, Zn, Sn, Si, Cu, Ga, Sb, Al, and Ge. Among them, B, Sn, Si, Al, and Ge are preferable, and Sn, Al, and Ge are more preferable. A represents I, Br, Cl, F, I, Br, and Cl are preferable, and I and Cl are particularly preferable. a to e represent the composition ratios of the respective elements, and a:b:c:d:e satisfies 1 to 12:0 to 1:1:2 to 12:0 to 5. a is further preferably 1 to 9, and more preferably 1.5 to 4. b is preferably 0 to 0.5. d is further preferably 3 to 7, and more preferably 3.25 to 4.5. e is further preferably 0 to 3, and more preferably 0 to 2. M and A may each use a single element or a plurality of elements.

[0036] In the formula, the composition ratios of Li, M, P, S, and A preferably have b = 0 and e = 1, more preferably b = 0, e = 1, and the ratio of a, c, and d (a:c:d) is a:c:d = 1 to 9:1:3 to 7, and even more preferably b = 0, e = 1, and a:c:d = 3 to 8:1:4 to 6. As the sulfide solid electrolyte satisfying these, an argyrodite-type sulfide solid electrolyte (Li6PS5Cl) can be mentioned.

[0037] When the inorganic solid electrolyte is in a particulate form, its particle diameter is, for example, 0.01 to 100 μm, preferably 0.1 to 20 μm.

[0038] In 100 parts by mass of the composite solid electrolyte of the present invention, the content of the inorganic solid electrolyte is preferably 70 parts by mass or more, more preferably 80 parts by mass or more, still more preferably 85 parts by mass or more, and particularly preferably 90 parts by mass or more as the lower limit. On the other hand, it is preferably 99 parts by mass or less, more preferably 98 parts by mass or less, still more preferably 97 parts by mass or less, and particularly preferably 96 parts by mass or less as the upper limit. When within these ranges, the electrical properties of the composite solid electrolyte are not impaired.

[0039] Also, for the purpose of improving the binding property between inorganic solid particles, a binder may be included, and known ones can be used. Specifically, fluororesin-based binders such as polyvinylidene fluoride, vinylidene fluoride - hexafluoropropylene copolymer, perfluoromethyl vinyl ether - tetrafluoroethylene copolymer, polytetrafluoroethylene, etc., rubber-based binders such as fluororubber, styrene - butadiene rubber, ethylene - propylene rubber, etc., polysaccharides such as carboxymethyl cellulose, alginic acid, sodium alginate, etc., and polyimide, etc. can be used.

[0040] In the present invention, when a binder is used, its usage amount is preferably 0.1 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, still more preferably 0.1 to 5 parts by mass with respect to 100 parts by mass of the inorganic solid electrolyte. When within this range, it has an excellent point in that it does not have an adverse effect on the ionic conductivity and can impart durability to the composite solid electrolyte.

[0041] Further, the composite solid electrolyte of the present invention may contain an electrolyte salt compound, which is composed of a cation selected from metal cations, ammonium ions, amidinium ions, and guanidinium ions, and an anion selected from chloride ions, bromide ions, iodide ions, perchlorate ions, thiocyanate ions, tetrafluoroborate ions, nitrate ions, AsF6 - , PF6 - , stearylsulfonate ions, octylsulfonate ions, dodecylbenzenesulfonate ions, naphthalenesulfonate ions, dodecylnaphthalenesulfonate ions, 7,7,8,8-tetracyano-p-quinodimethane ions, X1SO3 - , [(X1SO2)(X2SO2)N] - , [(X1SO2)(X2SO2)(X3SO2)C] - , and [(X1SO2)(X2SO2)YC] - . However, X1, X2, X3, and Y are electron-withdrawing groups. Preferably, X1, X2, and X3 are each independently a perfluoroalkyl group having 1 to 6 carbon atoms or a perfluoroaryl group having 6 to 18 carbon atoms, and Y is a nitro group, a nitroso group, a carbonyl group, a carboxyl group, or a cyano group. X1, X2, and X3 may be the same or different from each other.

[0042] As the metal cation, a transition metal cation can be used. Preferably, a metal cation selected from Mn, Fe, Co, Ni, Cu, Zn, and Ag metals is used. Also, favorable results can be obtained by using a metal cation selected from Li, Na, K, Rb, Cs, Mg, Ca, and Ba metals. It is possible to use two or more of the aforementioned compounds as the electrolyte salt compound. Among these, Li salt compounds are preferred, and Li salt compounds having a wide potential window are used. For example, LiBF4, LiPF6, LiClO4, LiCF3SO3, LiN(CF3SO2)2, LiN(C2F5SO2)2, LiN[CF3SC(C2F5SO2)3]2, etc. can be mentioned, but it is not limited to these. These may be used alone or in combination of two or more.

[0043] In addition, a room temperature molten salt can be used as the electrolyte salt compound. When using a room temperature molten salt as the electrolyte, due to the physical property of the salt that it is liquid at room temperature, it can exhibit the same solvent effect as when a non-aqueous organic solvent is further added only with this addition.

[0044] The room temperature molten salt refers to a salt that is at least partially liquid at room temperature, and room temperature refers to the temperature range in which the power supply is assumed to normally operate. The temperature range in which the power supply is assumed to normally operate has an upper limit of about 120°C, and in some cases about 60°C, and a lower limit of about -40°C, and in some cases about -20°C.

[0045] The room temperature molten salt is also called an ionic liquid, and quaternary ammonium organic cations of the pyridine type, aliphatic amine type, and alicyclic amine type are known. Examples of the quaternary ammonium organic cation include imidazolium ions such as dialkylimidazolium and trialkylimidazolium, tetraalkylammonium ions, alkylpyridinium ions, pyrazolium ions, pyrrolidinium ions, piperidinium ions, etc. In particular, imidazolium cations are preferred.

[0046] Examples of the imidazolium cation include dialkylimidazolium ions and trialkylimidazolium ions. Examples of the dialkylimidazolium ion include 1,3-dimethylimidazolium ion, 1-ethyl-3-methylimidazolium ion, 1-methyl-3-ethylimidazolium ion, 1-methyl-3-butylimidazolium ion, 1-butyl-3-methylimidazolium ion, etc., and examples of the trialkylimidazolium ion include 1,2,3-trimethylimidazolium ion, 1,2-dimethyl-3-ethylimidazolium ion, 1,2-dimethyl-3-propylimidazolium ion, 1-butyl-2,3-dimethylimidazolium ion, etc., but are not limited thereto.

[0047] Examples of the tetraalkylammonium ion include, but are not limited to, trimethylethylammonium ion, dimethyldiethylammonium ion, trimethylpropylammonium ion, trimethylhexylammonium ion, tetraamylammonium ion, and the like.

[0048] Examples of the alkylpyridinium ion include, but are not limited to, N-methylpyridinium ion, N-ethylpyridinium ion, N-propylpyridinium ion, N-butylpyridinium ion, 1-ethyl-2-methylpyridinium ion, 1-butyl-4-methylpyridinium ion, 1-butyl-2,4-dimethylpyridinium ion, and the like.

[0049] Note that the room temperature molten salts having these cations may be used alone or in combination of two or more.

[0050] Examples of the anion include halide ions such as chloride ion, bromide ion, and iodide ion; inorganic acid ions such as perchlorate ion, thiocyanate ion, tetrafluoroborate ion, nitrate ion, hexafluorohuminate ion, and hexafluorophosphate ion; and organic acid ions such as stearylsulfonate ion, octylsulfonate ion, dodecylbenzenesulfonate ion, naphthalenesulfonate ion, dodecylnaphthalenesulfonate ion, and 7,7,8,8-tetracyano-p-quinodimethane ion.

[0051] In the present invention, when using the electrolyte salt compound, the amount used is preferably such that the value of the number of moles of the electrolyte salt compound / the total number of moles of ether oxygen atoms of the polyether copolymer is 0.0001 to 5, more preferably in the range of 0.001 to 0.5.

[0052] Since the polyether copolymer used in the composite solid electrolyte of the present invention contains a crosslinking group, the polyether copolymer can be crosslinked by adding a thermal polymerization initiator or a photo-reaction initiator to cause a crosslinking reaction. Crosslinking the polyether copolymer is excellent in that it can ensure higher resistance to external pressure compared to the uncrosslinked case.

[0053] Examples of the thermal polymerization initiator include radical initiators selected from organic peroxide-based, azo compound-based, etc.

[0054] Examples of the organic peroxide-based include those commonly used for crosslinking purposes such as ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, diacyl peroxide, peroxyester, etc., and 1,1-bis(tert-butylperoxy)-3,3,5-trimethylcyclohexane, di-tert-butyl peroxide, tert-butyl cumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-bis(tert-butylperoxy)hexane, benzoyl peroxide, tert-butyl peroxy-2-ethylhexanoate, etc.

[0055] Examples of the azo compound-based include those commonly used for crosslinking purposes such as azonitrile compounds, azoamide compounds, azoamidine compounds, etc., and 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile), 2,2-azobis(2-methyl-N-phenylpropionamidine)·dihydrochloride, 2,2'-azobis[2-(2-imidazolin-2-yl)propane], 2,2'-azobis[2-methyl-N-(2-hydroxyethyl)propionamide], 2,2'-azobis(2-methylpropane), 2,2'-azobis[2-(hydroxymethyl)propionitrile], etc.

[0056] Examples of the photoinitiator that can be used in the present invention include alkylphenone-based, benzophenone-based, acylphosphine oxide-based, titanocenes, triazines, bisimidazoles, oxime esters, and the like. Alkylphenone-based, benzophenone-based, and acylphosphine oxide-based photoinitiators are preferred. It is also possible to use two or more types of photoinitiators in combination.

[0057] Specific examples of the alkylphenone-based photoinitiator include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-[4-[4-(2-hydroxy-2-methylpropionyl)benzyl]phenyl]-2-methylpropan-1-one, and the like. 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexyl phenyl ketone, and 2-hydroxy-2-methyl-1-phenylpropan-1-one are preferred.

[0058] Specific examples of the benzophenone-based photoinitiator include benzophenone, 2-chlorobenzophenone, 4,4'-bis(diethylamino)benzophenone, 4,4'-bis(dimethylamino)benzophenone, methyl-2-benzoylbenzoate, and the like. Benzophenone, 4,4'-bis(diethylamino)benzophenone, and 4,4'-bis(dimethylamino)benzophenone are preferred.

[0059] Specific examples of the acylphosphine oxide-based photopolymerization initiator include 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, and the like. Bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide is preferred.

[0060] The amount of the thermal polymerization initiator is preferably in the range of 0.01 to 10 parts by mass, more preferably 0.1 to 4.0 parts by mass, based on 100 parts by mass of the polyether copolymer of the present invention. The amount of the photoinitiator is preferably in the range of 0.01 to 6.0 parts by mass, more preferably 0.1 to 4.0 parts by mass, based on 100 parts by mass of the polyether copolymer of the present invention.

[0061] When using a photoinitiator, a crosslinking aid may be used in combination. The crosslinking aid is usually a polyfunctional compound (for example, a compound containing at least 2 of CH2=CH-, CH2=CH-CH2-, CF2=CF-). Specific examples of the crosslinking aid are triallyl cyanurate, triallyl isocyanurate, triacryl formal, triallyl trimellitate, N,N'-m-phenylene bismaleimide, dipropargyl terephthalate, diallyl phthalate, tetraallyl terephthalamide, triallyl phosphate, hexafluorotriallyl isocyanurate, N-methyltetrafluorodiallyl isocyanurate, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate, etc.

[0062] When performing crosslinking by heat, it can be carried out by heating at a temperature setting of about room temperature to 200°C for about 10 minutes to 24 hours.

[0063] When performing crosslinking by light, active energy rays such as ultraviolet rays, visible light rays, and electron beams can be used. Ultraviolet rays are particularly preferred in terms of the price of the apparatus and ease of control. Specifically, a xenon lamp, a mercury lamp, a high-pressure mercury lamp, and a metal halide lamp can be used. For example, the polymer electrolyte composition can be irradiated at a wavelength of 365 nm and a light intensity of 1 to 50 mW / cm 2 for 0.1 to 30 minutes to carry out the crosslinking.

[0064] Young's modulus measurement by nanoindentation method The nanoindentation method can measure the hardness-indentation depth curve and the Young's modulus-indentation depth curve by the continuous stiffness measurement method (CSM), and obtain the Young's modulus of the target material. In the continuous stiffness measurement method, during the indentation test of the sample, the indenter is slightly vibrated, and the properties of the material are measured as a function of depth, load, time, or frequency. From the vibration component of the displacement generated with respect to the force applied to the sample and the phase difference between the displacement and the load, the Young's modulus with respect to the depth is calculated.

[0065] In the measurement of the Young's modulus by the nanoindentation method for the composite solid electrolyte of the present invention, the indentation depth range from 0 nm to 10,000 nm is set as the measurement interval, and the Young's modulus (E MIN ) at the minimum value within the interval and the Young's modulus (E 10000 ) at 10,000 nm, the ratio (E 10000 / E MIN ) is preferably in the range of 1.10 to 2.50. Specifically, as the lower limit, it is preferably 1.10 or more, more preferably 1.15 or more, further preferably 1.20 or more, and particularly preferably 1.25 or more. On the other hand, as the upper limit, it is preferably 2.50 or less, more preferably 2.25 or less, further preferably 2.00 or less, and particularly preferably 1.75 or less. By being within these ranges, resistance to external pressure can be obtained without impairing the electrical properties.

[0066] Manufacturing method of composite solid electrolyte For the composite solid electrolyte used in the present invention, methods generally used in the art can be adopted according to its use and shape. For example, it can be prepared by mixing a polyether copolymer and an inorganic solid electrolyte in a mortar and pelletizing by stirring, and then press-molding into the required shape. As another method, it can be prepared by applying and drying a slurry solution containing (mixed with) a polyether copolymer, an inorganic solid electrolyte, and an organic solvent. The aforementioned compounds can be used for the ionic liquid.

[0067] There are no restrictions on the organic solvent as long as it can disperse the polyether copolymer and the inorganic solid electrolyte. Specifically, for example, hydrocarbon solvents such as n-pentane, n-hexane, n-heptane, n-octane, cyclopentane, cyclohexane, cyclobutane, etc.; aromatic solvents such as toluene, xylene, etc.; ketone solvents such as methyl isobutyl ketone, etc.; ether solvents such as n-butyl ether, dioxane, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol, etc.; ester solvents such as ethyl acetate, n-butyl acetate, isobutyl acetate, ethylene glycol monomethyl ether acetate, butyl carbitol acetate, etc.; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, etc.; alcohol solvents such as ethanol, isopropanol, n-butanol, sec-butanol, isobutanol, etc.; amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, N-methylformamide, N-methylacetamide, N-methylpropionamide, N-methyl-2-pyrrolidone, etc. can be mentioned. Among them, it is preferable to use hydrocarbon solvents, aromatic solvents, ketone solvents, and ether solvents, more preferably hydrocarbon solvents and aromatic solvents, and even more preferably n-hexane, n-heptane, and toluene.

[0068] <All-solid-state battery> The all-solid-state battery using the composite solid electrolyte of the present invention is composed of at least a positive electrode, a composite solid electrolyte, and a negative electrode, and can be manufactured by laminating these. Specifically, it is manufactured by sandwiching the composite solid electrolyte between the positive electrode and the negative electrode.

[0069] Positive electrode For the positive electrode used in the all-solid-state battery of the present invention, a positive electrode composite material containing at least a positive electrode active material is used and is configured as the positive electrode.

[0070] Positive electrode composite material The positive electrode mixture used for the positive electrode of the present invention contains at least a positive electrode active material, and optionally contains an inorganic solid electrolyte (including the composite solid electrolyte of the present invention), a conductive assistant, and a binder.

[0071] Positive electrode active material The positive electrode active material used in the present invention is an alkali metal-containing composite oxide having a composition of any one of AMO2, AM2O4, A2MO3, and AMBO4. A is an alkali metal, M consists of a single or two or more transition metals, and a part thereof may contain a non-transition metal. B consists of P, Si, or a mixture thereof. The positive electrode active material is preferably in powder form, and those having a particle diameter of preferably 50 μm or less, more preferably 20 μm or less are used. These positive electrode active materials have an electromotive force of 3 V (vs. Li / Li+) or more.

[0072] Preferred specific examples of the positive electrode active material include Li x CoO2, Li x NiO2, Li x MnO2, Li x CrO2, Li x FeO2, Li x Co a Mn 1-a O2, LixCo a Ni 1-a O2, Li x Co a Cr 1-a O2, Li x Co a FE -a O2, Li x Co a Ti 1-a O2, Li x Mn a Ni 1-a O2, Li x Mn a Cr 1-a O2, Li x Mn a Fe -a O2, Li x Mn a Ti 1-a O2, Li x Ni a Cr 1-a O2, Lix Ni a Fe -a O2, Li x Ni a Ti 1-a O2, Li x Cr a Fe -a O2, Li x Cr a Ti 1-a O2, Li x Fe a Ti 1-a O2, Li x Co b Mn c Ni 1-b-C O2, Li x Ni a Co b Al c O2, Li x Cr b Mn c Ni 1-b-C O2, Li x Fe b Mn c Ni 1-b-C O2, Li x Ti b Mn c Ni 1-b-C O2, Li x Mn2O4, Li x Mn d Co 2-d O4, Li x Mn d Ni 2-d O4, Li x Mn d Cr 2-d O4, Li x Mn d Fe 2-d O4, Li x Mn d Ti 2-d O4, Li y MnO3, Li y Mn e Co 1-e O3, Li y Mn e Ni 1-e O3, Li y Mn e Fe -e O3, Li y Mne Ti 1-e O3, Li x CoPO4, Li x MnPO4, Li x NiPO4, Li x FePO4, Li x CofMn 1-f PO4, Li x Co f Ni 1-f PO4, Li x Co f Fe -f PO4, Li x Mn f Ni 1-f PO4, Li x Mn f Fe -f PO4, LixNi f Fe -f PO4, Li y CoSiO4, Li y MnSiO4, Li y NiSiO4, Li y FeSiO4, Li y Co g Mn 1-g SiO4, Li y CogNi 1-g SiO4, Li y Co g Fe -g SiO4, Li y Mn g Ni 1-g SiO4, Li y Mn g FE -g SiO4, Li y Ni g Fe -g SiO4, Li y CoP h Si 1-h O4, Li y MnP h Si 1-h O4, Li y NiP h Si 1-h O4, Li y FeP h Si 1-h O4, Li y Co g Mn 1-g Ph Si 1-h O4, Li y Co g Ni 1-g P h Si 1-h O4, Li y Co g Fe -g P h Si 1-h O4, Li y Mn g Ni 1-g P h Si 1-h O4, Li y Mn g Fe[[ID=3⑧]] -g P h Si 1-h O4, Li y Ni g Fe -g P h Si 1-h Lithium-containing composite oxides such as O4 can be mentioned. (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, provided that 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, h = 0.01 to 0.99.)

[0073] Among the preferred cathode active materials used in all-solid-state batteries, more preferred cathode active materials specifically include LixCoO2, LixNiO2, LixMnO2, LixCrO2, 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 -fPO4 can be cited. (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, provided that 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. Note that the values of x and y above increase or decrease by charge and discharge.)

[0074] The content of the positive electrode active material in 100 parts by mass of the positive electrode composite material is preferably 30 to 100 parts by mass, more preferably 40 to 100 parts by mass, and even more preferably 50 to 100 parts by mass.

[0075] In terms of ensuring ion conductivity, the composite solid electrolyte and inorganic solid electrolyte of the present invention can be included. When using an inorganic solid electrolyte, the above-mentioned inorganic solid electrolyte can be used, and it may be the same inorganic solid electrolyte or different inorganic solid electrolytes.

[0076] The content of the solid electrolyte in 100 parts by mass of the positive electrode composite material is preferably 0 to 70 parts by mass, more preferably 0 to 65 parts by mass, and even more preferably 0 to 50 parts by mass.

[0077] When using a conductive assistant, a known conductive assistant can be used, such as conductive carbon black such as graphite, furnace black, acetylene black, ketjen black, carbon fibers such as carbon nanotubes (CNT), or metal powder, etc. These conductive assistants may be used alone or in combination of two or more.

[0078] The content of the conductive assistant in 100 parts by mass of the positive electrode composite material is preferably 0 to 70 parts by mass, more preferably 0 to 65 parts by mass, and even more preferably 0 to 50 parts by mass.

[0079] For the purpose of improving the binding property of the positive electrode active material, it may contain a binder, and any known binder for the positive electrode can be used. Specifically, fluorine-based resins such as polyvinylidene fluoride, vinylidene fluoride - hexafluoropropylene copolymer, perfluoromethyl vinyl ether - tetrafluoroethylene copolymer, polytetrafluoroethylene, and fluororubber, hydrocarbon-based elastomers such as styrene - butadiene copolymer and ethylene - propylene copolymer, polysaccharides such as carboxymethyl cellulose, alginic acid, and sodium alginate, and polyimide can be used.

[0080] The content of the binder in 100 parts by mass of the positive electrode composite material is preferably 0 to 70 parts by mass, more preferably 0 to 65 parts by mass, and even more preferably 0 to 50 parts by mass.

[0081] In addition, when it is difficult to maintain the shape of the positive electrode composite material due to external pressure such as pressing, or when the positive electrode composite material alone cannot ensure electron conductivity and ion conductivity, etc., a current collector for the positive electrode can be used as a support for the positive electrode composite material as needed. Specifically, metals such as aluminum, nickel, stainless steel, gold, platinum, and titanium are used as the current collector for the positive electrode.

[0082] The thickness of the current collector for the positive electrode is not particularly limited, but for example, it is about 5 to 50 μm, preferably about 10 to 20 μm.

[0083] Manufacturing method of positive electrode The manufacturing method of the positive electrode is not particularly limited, and a general method is used. It is carried out by uniformly coating the positive electrode material to an appropriate thickness by a wet method such as the doctor blade method, the applicator method, or the silk screen method.

[0084] When carried out by the above wet method, it may contain an organic solvent and water to form a slurry. Water is not particularly limited, and generally used water can be used. Specific examples thereof include tap water, distilled water, ion-exchanged water, and ultrapure water. Among them, distilled water, ion-exchanged water, and ultrapure water are preferred. As the organic solvent, it can be selected from alcohol, acetone, acetonitrile, methyl ethyl ketone, toluene, hexane, heptane, tetrahydrofuran, and N-methyl-2-pyrrolidone. Among these, it is more preferable to use an organic solvent, and it is even more preferable to use toluene, hexane, heptane, or N-methyl-2-pyrrolidone.

[0085] The solid content concentration in the slurry is preferably 10 to 90% by mass, more preferably 20 to 85% by mass, and particularly preferably 20 to 80% by mass.

[0086] The preparation method is not particularly limited, and a binder, a conductive aid, water, etc. may be dispersed using an ordinary stirrer, disperser, kneader, planetary ball mill, homogenizer, etc. In order to improve the dispersion efficiency, it may be heated within a range that does not affect the material.

[0087] For example, in the doctor blade method, after applying the slurry of the positive electrode composite material on a release film or a positive electrode current collector, it is made uniform to an appropriate thickness by a blade having a predetermined slit width. Then, in order to remove excess organic solvent or water, it is dried, for example, with hot air at 100 °C or in a vacuum state at 80 °C. After drying, a positive electrode is manufactured by press molding with a press device. Heat treatment may be performed again after pressing to remove water, solvent, emulsifier, etc.

[0088] Negative electrode The negative electrode used in the all-solid-state battery of the present invention is composed of a negative electrode composite material containing at least a negative electrode active material.

[0089] Negative electrode composite material The negative electrode composite material used for the negative electrode of the present invention contains at least a negative electrode active material, and optionally contains an inorganic solid electrolyte (including the composite solid electrolyte of the present invention), a conductive auxiliary agent, and a binder.

[0090] Negative electrode active material As the negative electrode active material used in the present invention, a carbon material (natural graphite, artificial graphite, amorphous carbon, etc.) having a structure (porous structure) capable of occluding and releasing lithium ions, or a silicon-based compound can be used. The particle size is preferably 10 nm or more and 100 μm or less, and more preferably 20 nm or more and 20 μm or less.

[0091] Examples of the carbon material 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, phenol resin fired body, polyacrylonitrile-based carbon fiber, etc., and graphite is preferred.

[0092] Examples of the silicon-based compound include Si element, alloy with Si, oxide containing Si, carbide 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 SiO x (0 < x ≤ 2) is preferred, and it is silicon monoxide (SiO), etc.

[0093] When using a carbon material or a silicon-based compound as the negative electrode active material, they may be composed of each alone or used in combination. When using the carbon material and the silicon-based compound in combination, it is preferable to contain them as follows.

[0094] The content of the carbon material with respect to the total amount of the negative electrode active material (100% by mass) is preferably 10% by mass or more, more preferably 20% by mass or more, further preferably 40% by mass or more, and particularly preferably 60% by mass or more as the lower limit. The upper limit is preferably 99% by mass or less, more preferably 98% by mass or less, and particularly preferably 96% by mass or less.

[0095] The content of the silicon-based compound with respect to the total amount of the negative electrode active material (100% by mass) is preferably 1% by mass or more, more preferably 2% by mass or more, particularly preferably 4% by mass or more as the lower limit, and preferably 90% by mass or less, more preferably 80% by mass or less, further preferably 60% by mass or less, and particularly preferably 40% by mass or less as the upper limit.

[0096] In addition, when a lithium-ion battery using the dissolution and precipitation of lithium is used, metallic lithium, a lithium alloy capable of occluding and releasing lithium, or the like can be used as the negative electrode active material.

[0097] Examples of the lithium alloy include a lithium-aluminum alloy, a lithium-tin alloy, a lithium-indium alloy, a lithium-silver alloy, a lithium-gold alloy, a lithium-zinc alloy, a lithium-germanium alloy, a lithium-silicon alloy, and the like. In addition, any material that can be alloyed with lithium using a known alloying method can be used.

[0098] The content of the negative electrode active material in 100 parts by mass of the negative electrode composite material is preferably 30 to 100 parts by mass, more preferably 40 to 100 parts by mass, and further preferably 50 to 100 parts by mass.

[0099] Also, if necessary, the composite solid electrolyte or the inorganic solid electrolyte of the present invention can be included in terms of ensuring ionic conductivity. When using an inorganic solid electrolyte, the above-described inorganic solid electrolyte can be used, and it may be the same inorganic solid electrolyte or different inorganic solid electrolytes.

[0100] The content of the solid electrolyte in 100 parts by mass of the negative electrode composite material is preferably 0 to 70 parts by mass, more preferably 0 to 60 parts by mass, and even more preferably 0 to 50 parts by mass.

[0101] When using a conductive assistant, a known conductive assistant can be used, and examples include conductive carbon blacks such as graphite, furnace black, acetylene black, and ketjen black, carbon fibers such as carbon nanotubes (CNT), or metal powders. These conductive assistants may be used alone or in combination of two or more.

[0102] The content of the conductive assistant in 100 parts by mass of the negative electrode composite material is preferably 0 to 70 parts by mass, more preferably 0 to 60 parts by mass, and even more preferably 0 to 50 parts by mass.

[0103] For the purpose of improving the binding property of the negative electrode active material, a binder may be included, and a known binder used for the negative electrode can be used. Specifically, fluorine-based resins such as polyvinylidene fluoride, vinylidene fluoride - hexafluoropropylene copolymer, perfluoromethyl vinyl ether - tetrafluoroethylene copolymer, polytetrafluoroethylene, and fluororubber, hydrocarbon-based elastomers such as styrene - butadiene copolymer and ethylene - propylene copolymer, polysaccharides such as carboxymethyl cellulose, alginic acid, and sodium alginate, and polyimide can be used.

[0104] The content of the binder in 100 parts by mass of the negative electrode composite material is preferably 0 to 70 parts by mass, more preferably 0 to 60 parts by mass, and even more preferably 0 to 50 parts by mass.

[0105] Similar to the positive electrode, when it is difficult for the negative electrode composite material to maintain its shape under external pressure such as pressing, or when the negative electrode composite material alone cannot ensure electron conductivity and ion conductivity, a current collector for the negative electrode can be used as a support as needed. The current collector for the negative electrode may form a lithium metal layer on the current collector by charging. When the lithium metal layer is formed, any current collector foil that does not react with lithium may be used. For example, metals, carbon, conductive polymers, etc. can be used, and preferably a metal is used. As the metal used for the current collector foil, usually, aluminum, platinum, nickel, tantalum, titanium, stainless steel, copper, other alloys, etc. are used.

[0106] The thickness of the current collector for the negative electrode is not particularly limited, but for example, it is about 5 to 50 μm, preferably about 10 to 20 μm.

[0107] Manufacturing method of negative electrode The manufacturing method of the negative electrode is not particularly limited, and general methods can be used. For example, it is carried out by uniformly coating to an appropriate thickness by a wet method such as a doctor blade method, an applicator method, or a silk screen method. As the drying method after coating, drying equipment such as a heater type, a hot air drying type, an infrared irradiation type, or a vacuum type can be used. To remove excess solvent, for example, it is dried at 50 to 150 °C (especially at 80 °C) under normal pressure or in a vacuum state.

[0108] When using the above wet method, it may contain an organic solvent and water to be in a slurry state. Water is not particularly limited, and generally used water can be used. Specific examples thereof include tap water, distilled water, ion-exchanged water, and ultrapure water. Among them, preferably distilled water, ion-exchanged water, and ultrapure water. As the organic solvent, it can be selected from alcohol, acetone, acetonitrile, methyl ethyl ketone, toluene, hexane, heptane, tetrahydrofuran, and N-methyl-2-pyrrolidone. Among these, it is more preferable to use an organic solvent, and it is even more preferable to use toluene, hexane, heptane, and N-methyl-2-pyrrolidone.

[0109] The solid content concentration in the slurry is preferably 10 to 90% by mass, more preferably 20 to 85% by mass, and particularly preferably 20 to 80% by mass.

[0110] The preparation method is not particularly limited, and a binder, a conductive auxiliary agent, water, etc. may be dispersed using a normal stirrer, disperser, kneader, planetary ball mill, homogenizer, etc. Heating may be performed within a range that does not affect the material in order to increase the dispersion efficiency.

[0111] For example, in the doctor blade method, after applying the slurry of the negative electrode constituent material to a metal electrode substrate, it is made uniform to an appropriate thickness by a blade having a predetermined slit width. After applying the active material to the electrode, in order to remove excess organic solvent or water, it is dried, for example, with hot air at 100 ° C or in a vacuum state at 80 ° C. The dried electrode is press-molded by a pressing device to produce an electrode material. Heat treatment may be performed again after pressing to remove water, organic solvent, emulsifier, etc.

[0112] Manufacturing method of all-solid-state battery Specifically exemplifying the manufacturing method of the all-solid-state battery of the present invention, It includes at least a step of compounding a polyether copolymer and an inorganic solid electrolyte, a positive electrode manufacturing step, a negative electrode manufacturing step, and a lamination step of laminating these.

Example

[0113] Examples are given below to explain the present invention in more detail, but the present invention is not limited to the examples described below as long as it does not exceed the gist of the invention.

[0114] [Synthesis example (manufacture of catalyst for polyether copolymerization)] 10 parts by mass of tributyltin chloride and 35 parts by mass of tributyl phosphate were placed in a three-necked flask equipped with a stirrer, a thermometer, and a distillation apparatus, and heated at 250 ° C for 20 minutes while stirring under a nitrogen stream to distill off the distillate to obtain a solid condensate as a residue. It was used as a polymerization catalyst in the following polymerization examples.

[0115] [Polymerization example 1] The inside of a 3 L four-necked glass flask was purged with nitrogen, and 1 g of the condensate shown in the synthesis example of the catalyst as a polymerization catalyst and 150 parts by mass of the glycidyl ether compound (a) corresponding to the following formula (1) adjusted to 10 ppm or less of water were charged: [Chemical formula] 30 parts by mass of allyl glycidyl ether corresponding to the following formula (3) and 1000 parts by mass of n-hexane as a solvent were charged, and while tracking the polymerization rate of the compound (a) by gas chromatography, 150 parts by mass of ethylene oxide corresponding to the following formula (2) was sequentially added. The polymerization temperature at this time was 20°C, and the reaction was carried out for 10 hours. The polymerization reaction was stopped by adding 1 mL of methanol. After taking out the polymer by decantation, it was dried at 40°C for 24 hours under normal pressure and further at 45°C for 10 hours under reduced pressure to obtain 280 parts by mass of the polymer. The weight average molecular weight and polymerization composition of the obtained polyether copolymer were determined by the following tests. The weight average molecular weight was 2.4 million, and the polymerization composition was, in terms of molar ratio, compound (a):ethylene oxide:allyl glycidyl ether = 20 mol%:78 mol%:2 mol%.

[0116] [Weight average molecular weight of polyether copolymer] Gel permeation chromatography (GPC) measurement was carried out, and the weight average molecular weight was calculated by conversion to standard polystyrene. The GPC measurement was carried out at 60°C using RID-6A (manufactured by Shimadzu Corporation), Shodex KD-807, KD-806, KD-806M, and KD-803 columns (all manufactured by Showa Denko K.K.) and DMF as a solvent.

[0117] [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 determined from the calculation result. As the apparatus, JNM ECZS-400 type manufactured by JEOL Ltd. was used.

[0118] [Example 1] 5 parts by mass of the polyether copolymer obtained in Overlap Example 1 and 95 parts by mass of an argyrodite-type sulfide solid electrolyte (manufactured by NEI, Li6PS5Cl) were dissolved in toluene as a dispersion medium to prepare a slurry solution of the composite solid electrolyte. Using this slurry solution, it was applied to a PET film, and the dispersion medium was removed by vacuum heating and drying to obtain Composite Solid Electrolyte 1. The obtained Composite Inorganic Electrolyte 1 was subjected to a load of 100 MPa or more using a flat press machine so as to have a diameter of 10 mm and a thickness of 0.5 to 2 mm to prepare Composite Solid Electrolyte Sheet 1. Using this Sheet 1, the following tests were conducted to evaluate Composite Solid Electrolyte 1. The results are shown in Table 1.

[0119] Young's modulus measurement by nanoindentation method Using a nanoindenter (Nano Indenter XP / DCM manufactured by MTS System), Young's modulus (abbreviation: E) of Composite Solid Electrolyte Sheet 1 prepared in Example 1 was measured at a penetration depth of 0 nm to 10,000 nm. As an evaluation method, the minimum value of Young's modulus (E MIN ) at a penetration depth of 0 nm to 10,000 nm and the Young's modulus (E 10000 ) at a penetration depth of 10,000 nm were used to calculate the ratio for evaluation. The calculation formula is as follows. Ratio = (E 10000 ) / (E MIN )

[0120] Fracture toughness Using the indentation method of generating cracks in the material by pressing a Vickers indenter on Composite Solid Electrolyte Sheet 1 prepared in Example 1, the fracture toughness value was calculated. The calculation formula is as follows. TIFF2025110603000008.tif1420 Here, α is a constant, E is Young's modulus, H is Vickers hardness, P is the pressing load, and C is half of the average crack length. The higher this value, the stronger the resistance to crack generation against external pressure in the vertical direction.

[0121] Shearing force (horizontal force) The composite solid electrolyte sheet 1 produced in Example 1 was evaluated for the horizontal force when the cutting blade was horizontally moved after cutting into the depth region (20 μm) to be evaluated with a cutting blade from the sample surface using a SAICAS tester (manufactured by Daipla Wintersteiger, DN-20S). The higher this value, the stronger the resistance to crack generation against the external pressure in the horizontal direction.

[0122] [Comparative example 1] A composite solid electrolyte sheet 2 was produced and the above evaluation was carried out in the same manner as in Example 1 except that the polyether copolymer was changed to polypropylene oxide (weight average molecular weight: 700,000). The results are shown in Table 1.

[0123] [Comparative example 2] A composite solid electrolyte sheet 3 was produced and the above evaluation was carried out in the same manner as in Example 1 except that a sheet was produced using only the all-dry type sulfide solid electrolyte without using the polyether copolymer. The results are shown in Table 1.

[0124]

Table 1

[0125] [Example 2] Using the composite solid electrolyte sheet 1 produced in Example 1, a stainless steel current collector for the negative electrode, a negative electrode using a Li-In alloy as the negative electrode composite material, a stainless steel current collector for the positive electrode, and a positive electrode using a mixture of NCM (lithium nickel cobalt manganate = 1 / 1 / 1) / all-dry type sulfide solid electrolyte / acetylene black as the positive electrode composite material, a pressed powder type all-solid-state battery was assembled in a glove box replaced with argon gas, and a cycle performance test was carried out to evaluate it as an electrolyte. The results are shown in Table 2.

[0126] Cycle characteristics test The cycle performance test was carried out using a charge-discharge device under test conditions (0.1C) where predetermined charging and discharging could be performed in 10 hours, with an upper limit of 3.48 V and a lower limit of 2.48 V. A constant current conduction test was carried out for 3 cycles to calculate the relative capacity and the charge-discharge retention rate. The test temperature was set to an environment of 25°C.

[0127] [Comparative example 3] A pellet-type all-solid-state battery was assembled and a cycle performance test was carried out in the same manner as in Example 2, except that a sheet made only of the argyrodite-type sulfide solid electrolyte of Comparative Example 2 was used. The results are shown in Table 2.

[0128]

Table 2

[0129] From Example 1, it was found that the composite solid electrolyte of the present invention has a ratio of Young's modulus of 1.10 or more, increasing the fracture toughness and horizontal force, and is excellent in resistance to external pressure in both the vertical and horizontal directions compared to Comparative Examples 1 and 2. Also, in the cycle test of the battery (Example 2) fabricated using the composite solid electrolyte of the present invention, it was found that the initial discharge capacity and the charge-discharge retention rate have equivalent performance compared to the battery fabricated using only the inorganic solid electrolyte.

Industrial Applicability

[0130] The solid electrolyte secondary battery using the composite solid electrolyte of the present invention is excellent in resistance to external pressure and does not lack electrical characteristics such as cycle performance, and thus can be suitably used for large battery applications such as in-vehicle applications for electric vehicles and hybrid electric vehicles, and storage batteries for household power storage.

Claims

1. comprising at least a polyether copolymer and an inorganic solid electrolyte, In the measurement of Young's modulus by nanoindentation method (indentation depth: 0 nm to 10000 nm), the ratio (E ＭＩＮ / E １００００ ), where E １００００ is the minimum value of Young's modulus and E ＭＩＮ is the Young's modulus at an indentation depth of 10000 nm, is 1.10 to 2.50 for the composite solid electrolyte.

2. The composite solid electrolyte according to Claim 1, wherein 2 to 20 parts by mass of the polyether copolymer is contained with respect to 100 parts by mass of the composite solid electrolyte.

3. The polyether copolymer is Formula (1): 【Chemical 1】 [Wherein, R is -CH ２ O(CR １ R ２ R ３ ). R １ , R ２ , R ３ is a hydrogen atom or -CH ２ O(CH ２ CH ２ O)nR ４ , and n and R ４ may be different among R １ , R ２ , R ３ . R ４ is an alkyl group having 1 to 12 carbon atoms or an aryl group, and n is an integer of 0 to 12.] 2 to 50 mol% of repeating units derived from the monomer represented by, and Formula (2): [Chemical 2] 40 to 97 mol% of repeating units derived from the monomer represented by, and Formula (3): 【Chemical Formula 3】 [In the formula, R ５ is a group having an ethylenically unsaturated group.] The composite solid electrolyte according to Claim 1, which is a polyether copolymer having 0.1 to 20 mol% of repeating units derived from the monomer represented by.

4. An all-solid-state battery comprising at least the composite solid electrolyte according to Claim 1, a negative electrode, and a positive electrode.

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