Solid-state battery and method for manufacturing solid-state battery

Abstract

The invention relates to a solid-state battery and a method for manufacturing the solid-state battery. The main purpose of the present invention is to provide a solid-state battery in which deterioration due to moisture is suppressed. The present disclosure solves the problem by providing a solid-state battery having a positive electrode active material layer, a negative electrode active material layer, and a solid electrolyte layer disposed between the positive electrode active material layer and the negative electrode active material layer, the positive electrode active material layer, the negative electrode active material layer, and the solid electrolyte layer contain a sulfide-coated solid electrolyte as an electrolyte, the sulfide-coated solid electrolyte has a sulfide solid electrolyte and a coating layer that coats the surface of the sulfide solid electrolyte, and the sulfide solid electrolyte contains at least Li element, S element, and P element. The coating layer contains a modifier, and the modifier is at least one of a compound represented by general formula (1), a compound represented by general formula (2), a polymer of the compound represented by general formula (1), and a polymer of the compound represented by general formula (2).

Description

Technical Field

[0001] The present disclosure relates to a solid battery and a method for manufacturing the solid battery. Background Art

[0002] Solid batteries are batteries having a solid electrolyte layer between a positive electrode and a negative electrode, and have the advantage of being easy to simplify safety devices compared to liquid batteries having an electrolyte solution containing a flammable organic solvent. In addition, sulfide solid electrolytes are known as solid electrolytes for solid batteries.

[0003] For example, Patent Document 1 discloses a method for producing a composite solid electrolyte in which the surface of a sulfide-based solid electrolyte is coated with a coating material. In addition, Patent Document 2 discloses a modified sulfide solid electrolyte comprising a sulfide-based solid electrolyte having a BET specific surface area of ​​10 m 2 / g or more and containing lithium atoms, sulfur atoms, phosphorus atoms and halogen atoms, and an epoxy compound, wherein the modified sulfide solid electrolyte has an infrared absorption spectrum of 2800 to 3000 cm -1 Has a peak.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2020-087633

[0007] Patent Document 2: International Publication No. 2022 / 158458 Summary of the invention

[0008] Problems to be solved by the invention

[0009] The Li ion conductivity of a sulfide solid electrolyte is easily reduced by moisture (for example, moisture in the atmosphere). Therefore, a solid battery containing a sulfide solid electrolyte is easily degraded by moisture.

[0010] The present disclosure has been made in view of the above-mentioned actual situation, and a main object of the present disclosure is to provide a solid battery in which degradation due to moisture is suppressed.

[0011] Means for solving problems

[0012] [1] A solid battery comprising a positive electrode active material layer, a negative electrode active material layer, and a solid electrolyte layer disposed between the positive electrode active material layer and the negative electrode active material layer, wherein the positive electrode active material layer, the negative electrode active material layer, and the solid electrolyte layer contain a coated sulfide solid electrolyte as an electrolyte, the coated sulfide solid electrolyte having a sulfide solid electrolyte and a coating layer covering a surface of the sulfide solid electrolyte, the sulfide solid electrolyte containing at least Li element, S element, and P element, the coating layer containing a modifier, the modifier being at least one of a compound represented by the following general formula (1), a compound represented by the following general formula (2), a polymer of a compound represented by the following general formula (1), and a polymer of a compound represented by the following general formula (2),

[0013]

Chemistry 1

[0014]

[0015] In formula (1), R 1 ~R 3 are each independently a hydrogen atom, a halogen atom, a monovalent hydrocarbon group or a monovalent halogenated hydrocarbon group, R 1 ~R 3 At least one of R is a monovalent hydrocarbon group or a monovalent halogenated hydrocarbon group, 1 ~R 3 at least one of which has an ether structure,

[0016] In formula (2), R 11 ~R 14 are each independently a hydrogen atom, a halogen atom, a monovalent silyl ether group, a monovalent hydrocarbon group or a monovalent halogenated hydrocarbon group, R 11 ~R 14 At least one of the groups is a silyl ether group.

[0017] [2] The solid battery according to [1], wherein the ratio of the modifier to the sulfide solid electrolyte is 12.5 mass % or less.

[0018] [3] The solid battery according to [1] or [2], wherein the ratio of the modifier to the sulfide solid electrolyte is 10.0 mass % or less.

[0019] [4] The solid battery according to any one of [1] to [3], wherein the modifier is at least one of a compound represented by the general formula (1) and a polymer of a compound represented by the general formula (1), and R 1 ~R 3 Any two of them are hydrogen atoms, and one is a monovalent hydrocarbon group having an ether structure.

[0020] [5] The solid battery according to any one of [1] to [4], wherein the modifier is at least one of a compound represented by the general formula (2) and a polymer of a compound represented by the general formula (2), and R 11 ~R 14 Three of them are monovalent silyl ether groups, and one is a monovalent hydrocarbon group.

[0021] [6] The solid battery according to any one of [1] to [5], wherein the modifier is at least one of the following compound A, the following compound B, the following compound C, the following compound D, a polymer containing at least one of the following compound A and the following compound B, and a polymer containing at least one of the following compound C and the following compound D,

[0022]

Chemistry 2

[0023]

[0024] [7] The solid battery according to [6], wherein the modifier is the compound A, the compound B or the compound C.

[0025] [8] The solid battery according to any one of [1] to [7], wherein the molecular weight or weight average molecular weight of the modifier is 60 or more.

[0026] [9] A solid battery according to any one of [1] to [8], wherein the proportion of the coated sulfide solid electrolyte relative to the total of the electrolytes in the positive electrode active material layer, the negative electrode active material layer and the solid electrolyte layer is 50% by mass or more and 100% by mass or less.

[0027]

[10] A method for manufacturing a solid battery, which is a method for manufacturing a solid battery according to any one of [1] to [9], comprising: a preparation step for preparing the coated sulfide solid electrolyte; and a layer formation step for forming the positive electrode active material layer, the negative electrode active material layer and the solid electrolyte layer using the coated sulfide solid electrolyte, wherein the layer formation step is performed in an environment with a dew point temperature of -50°C or above.

[0028]

[11] The method for manufacturing a solid battery according to

[10] , wherein the layer forming step is performed in an environment with a dew point temperature of -30°C or less.

[0029] Effects of the Invention

[0030] The present disclosure achieves the effect of being able to provide a solid battery in which degradation due to moisture is suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a schematic cross-sectional view illustrating a solid state battery in the present disclosure.

[0032] Description of Reference Numerals

[0033] 1…Positive electrode active material layer

[0034] 2…Negative electrode active material layer

[0035] 3…Solid electrolyte layer

[0036] 4…Positive electrode collector

[0037] 5…Negative electrode collector

[0038] 10…Solid-state batteries DETAILED DESCRIPTION

[0039] The solid battery and the method for manufacturing the solid battery in the present disclosure are described in detail below. The following figures are schematic representations, and the size and shape of each part are exaggerated as appropriate for easier understanding.

[0040] A. Solid state battery

[0041] Figure 1 This is a schematic cross-sectional view illustrating a solid state battery in the present disclosure. Figure 1 The solid battery 10 shown has a positive electrode active material layer 1, a negative electrode active material layer 2, and a solid electrolyte layer 3 disposed between the positive electrode active material layer 1 and the negative electrode active material layer 2. In addition, the solid battery 10 generally has a positive electrode collector 4 that collects electrons from the positive electrode active material layer 1 and a negative electrode collector 5 that collects electrons from the negative electrode active material layer 2. In particular, in the solid battery 10, the positive electrode active material layer 1, the negative electrode active material layer 2, and the solid electrolyte layer 3 contain a predetermined coated sulfide solid electrolyte as an electrolyte.

[0042] According to the present disclosure, since the positive electrode active material layer, the negative electrode active material layer, and the solid electrolyte layer contain a predetermined coated sulfide solid electrolyte as an electrolyte, a solid battery is provided in which degradation due to moisture is suppressed.

[0043] 1. Coated sulfide solid electrolyte

[0044] The positive electrode active material layer, the negative electrode active material layer, and the solid electrolyte layer of the solid battery in the present disclosure contain a coated sulfide solid electrolyte as an electrolyte.

[0045] The coated sulfide solid electrolyte comprises a sulfide solid electrolyte and a coating layer that covers the surface of the sulfide solid electrolyte and contains a modifier.

[0046] (1) Sulfide solid electrolyte

[0047] The sulfide solid electrolyte contains at least Li element, S element, and P element. In addition, the sulfide solid electrolyte may further contain at least one of O element and a halogen element (for example, at least one of F element, Cl element, Br element, and I element).

[0048] The sulfide solid electrolyte preferably contains sulfur (S) as a main component of the anion element.

[0049] Examples of sulfide solid electrolytes include Li 2 SP 2 S 5 , Li 2 SP 2 S 5 -LiI, Li 2 SP 2 S 5 -GeS 2 , Li 2 SP 2 S 5 -Li 2 O. Li 2 SP 2 S 5 -Li 2 O-LiI、Li 2 SP 2 S 5 -LiI-LiBr, Li 2 S-SiS 2 , Li 2 S-SiS 2 -LiI, Li 2 S-SiS 2 -LiBr, Li 2 S-SiS 2 -LiCl, Li 2 S-SiS 2 -B 2 S 3 -LiI, Li 2 S-SiS 2 -P 2 S 5 -LiI, Li 2 SB 2 S 3 , Li 2 SP 2 S 5 -Z m S n (where m and n are positive numbers. Z is any one of Ge, Zn, and Ga.) Li 2 S-GeS2 , Li 2 S-SiS 2 -Li 3 PO 4 , Li 2 S-SiS 2 -Li x MO y (Wherein, x and y are positive numbers. M is any one of P, Si, Ge, B, Al, Ga, and In.)

[0050] The sulfide solid electrolyte may have, for example, xLi 2 S·(100-x)P 2 S 5 (70≤x≤80),yLiI·zLiBr·(100-yz)(xLi 2 S·(1-x)P 2 S 5 The composition represented by )(0.7≤x≤0.8, 0≤y≤30, 0≤z≤30).

[0051] In addition, the sulfide solid electrolyte may have a composition represented by the following general formula (1).

[0052] Li 4-x Ge 1-x P x S 4 (0<x<1) ···Formula (1)

[0053] In formula (1), at least a portion of Ge may be replaced by at least one selected from Sb, Si, Sn, B, Al, Ga, In, Ti, Zr, V and Nb. In addition, at least a portion of P may be replaced by at least one selected from Sb, Si, Sn, B, Al, Ga, In, Ti, Zr, V and Nb. A portion of Li may be replaced by at least one selected from Na, K, Mg, Ca and Zn. A portion of S may be replaced by a halogen. The halogen is at least one of F, Cl, Br and I.

[0054] The types of atoms constituting the sulfide solid electrolyte can be confirmed using, for example, an ICP emission spectrometer.

[0055] The sulfide solid electrolyte may be an amorphous sulfide solid electrolyte such as a glass-based sulfide solid electrolyte (sulfide glass). In addition, the sulfide solid electrolyte may be a crystalline sulfide solid electrolyte such as a glass-ceramic sulfide solid electrolyte. The crystalline sulfide solid electrolyte can be obtained by heating an amorphous sulfide solid electrolyte to a temperature higher than the crystallization temperature.

[0056] Examples of the crystal structure of the crystalline sulfide solid electrolyte include Li 3 PS 4 Crystal structure, Li 4 P 2 S 6 Crystal structure, Li 7 PS 6 Crystal structure, Li 7 P 3 S 11 Crystal structure, crystal structure having peaks near 2θ=20.2° and 23.6° (for example, Japanese Patent Application Publication No. 2013-16423), etc. In addition, as other crystal structures, for example, Li 4-x Ge 1-x P x S 4 The thio-LISICON Region II crystal structure (see Kanno et al., Journal of The Electrochemical Society, 148 (7) A742-746 (2001)) is similar to Li 4-x Ge 1-x P x S 4 It is a crystal structure similar to thio-LISICONRegion II type (see Solid State Ionics, 177 (2006), 2721-2725)).

[0057] The shape of the sulfide solid electrolyte is not particularly limited, and may be, for example, a particle shape. The average particle size (D 50 ) is, for example, 0.01 μm or more and 500 μm or less, and may be 0.1 μm or more and 200 μm or less. 50 ) refers to the cumulative 50% particle size in a volume-based particle size distribution obtained using a laser diffraction particle size distribution measuring apparatus.

[0058] (2) Coating layer

[0059] The coating layer covers the surface of the sulfide solid electrolyte and contains a predetermined modifier.

[0060] The modifier is at least one of a compound represented by the following general formula (1), a compound represented by the following general formula (2), a polymer of a compound represented by the following general formula (1), and a polymer of a compound represented by the following general formula (2). That is, the coating layer may contain one modifier or two or more modifiers.

[0061]

Chemistry 3

[0062]

[0063] In formula (1), R 1 ~R 3 are each independently a hydrogen atom, a halogen atom, a monovalent hydrocarbon group or a monovalent halogenated hydrocarbon group, R 1 ~R 3 At least one of R is a monovalent hydrocarbon group or a monovalent halogenated hydrocarbon group, 1 ~R 3 At least one of the compounds has an ether structure.

[0064] In formula (2), R 11 ~R 14 are each independently a hydrogen atom, a halogen atom, a monovalent silyl ether group, a monovalent hydrocarbon group or a monovalent halogenated hydrocarbon group, R 11 ~R 14 At least one of the groups is a silyl ether group.

[0065] First, the general formula (1) will be described. In the formula (1), examples of the halogen atom include fluorine, chlorine, bromine, and iodine. Among these, fluorine, chlorine, and bromine are preferred, and fluorine is more preferred.

[0066] In formula (1), the number of carbon atoms in the monovalent hydrocarbon group is, for example, 1 to 20, 3 to 15, or 5 to 10. The above range is preferred from the viewpoint of suppressing battery resistance.

[0067] Examples of the monovalent hydrocarbon group include aliphatic hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups. Of these, aliphatic hydrocarbon groups or alicyclic hydrocarbon groups are preferred, and aliphatic hydrocarbon groups are more preferred. The aliphatic hydrocarbon group may be straight-chain or branched, and is preferably branched.

[0068] As the aliphatic hydrocarbon group, for example, alkyl and alkenyl groups can be listed. Among these, alkyl groups are preferred. As the alicyclic hydrocarbon group, for example, cycloalkyl and cycloalkenyl groups can be listed. As the aromatic hydrocarbon group, for example, phenyl, naphthyl, biphenyl, diphenylmethyl, trityl, anthracenyl, peryl and pyrenyl can be listed. A part of the aromatic hydrocarbon group may be substituted by hydroxyl group, the above-mentioned monovalent aliphatic hydrocarbon group (such as alkyl, alkenyl) and the like. In the present disclosure, for example, benzyl and the like are also included in the aromatic hydrocarbon group. Among them, the hydrocarbon group is a group containing at least carbon atoms and hydrogen atoms, and may be a group further containing heteroatoms such as oxygen atoms. For example, the monovalent hydrocarbon group may contain at least one of an ether structure (ether group) and an epoxide structure (epoxy group).

[0069] Examples of the monovalent halogenated hydrocarbon group include groups in which a part of the above-mentioned monovalent hydrocarbon group is substituted with a halogen atom. The halogen atom is preferably fluorine, chlorine, or bromine, and more preferably fluorine.

[0070] In the general formula (1), preferably R 1 ~R 3 Any two of them are hydrogen atoms, and one is a monovalent hydrocarbon group or a monovalent halogenated hydrocarbon group having an ether structure. 1 ~R 3 Any two of them are hydrogen atoms, and one is a monovalent hydrocarbon group having an ether structure. This is from the viewpoint of suppressing battery resistance.

[0071] Examples of the compound satisfying the general formula (1) include the following compounds A and B. The compounds satisfying the general formula (1) are not limited to these.

[0072]

Chemistry 4

[0073]

[0074] The modifier may be a polymer of a compound represented by the general formula (1). The polymer may consist only of the compound represented by the general formula (1). For example, it may be a polymer composed of the above-mentioned compound A, a polymer composed of the above-mentioned compound B, or a polymer composed of the above-mentioned compound A and compound B. In addition, within the scope of not significantly damaging the effect of the present disclosure, the polymer may also be a polymer copolymerized with other units. Furthermore, in the present disclosure, the so-called polymer of a compound represented by the general formula (1) refers to a compound formed by the polymerization of two or more compounds represented by the general formula (1). In addition, in the coating layer, the presence of the compound represented by the general formula (1) and its polymer can be confirmed by GC-MS.

[0075] Next, the general formula (2) will be described. It should be noted that the halogen atom, the monovalent hydrocarbon group and the monovalent halogenated hydrocarbon group are the same as those in the general formula (1), and thus their description is omitted here.

[0076] The monovalent silyl ether group is preferably represented by *-O-Si-(R 20 ) 3 In the above groups, R 20 are each independently a hydrogen atom or a monovalent hydrocarbon group, R 20 At least one of R is a monovalent hydrocarbon group. 20 Preferably, it is a monovalent hydrocarbon group, preferably an aliphatic hydrocarbon group or an alicyclic hydrocarbon group, and more preferably an aliphatic hydrocarbon group. The aliphatic hydrocarbon group may be linear or branched, and preferably branched. The monovalent hydrocarbon group is the same as that in the general formula (1), and therefore is omitted here. In the above groups, * represents a bonding portion to Si in the general formula (2).

[0077] In the general formula (2), preferably R 11 ~R 14At least two of the groups are monovalent silyl ether groups, more preferably at least three are monovalent silyl ether groups, and further preferably three are monovalent silyl ether groups and one is a monovalent hydrocarbon group. This is from the viewpoint of suppressing battery resistance.

[0078] Examples of the compound satisfying the general formula (2) include the following compound C and compound D. The compound satisfying the general formula (2) is not limited thereto.

[0079]

Chemistry 5

[0080]

[0081] The modifier may be a polymer of a compound represented by the general formula (2). The polymer may consist only of the compound represented by the general formula (2). For example, it may be a polymer composed of the above-mentioned compound C, or it may be a polymer composed of the above-mentioned compound D. In addition, within the scope of not significantly damaging the effect of the present disclosure, the polymer may be a polymer copolymerized with other units. Furthermore, in the present disclosure, the so-called polymer of a compound represented by the general formula (2) refers to a compound formed by the polymerization of two or more compounds represented by the general formula (2). In addition, in the coating layer, the presence of the compound represented by the general formula (2) and its polymer can be confirmed by GC-MS.

[0082] The molecular weight of the modifier is not particularly limited, and may be, for example, 60 or more, 60 or more and 10000 or less, or 300 or more and 5000 or less. This is from the viewpoint of suppressing battery resistance.

[0083] The weight average molecular weight of the modifier is not particularly limited, and is, for example, 60 or more, 60 or more and 10000 or less, or 300 or more and 5000 or less. The weight average molecular weight can be determined by gel permeation chromatography (GPC) in terms of polystyrene.

[0084] The thickness (average thickness) of the coating layer is not particularly limited, and may be, for example, 3 nm or more, 5 nm or more, or 10 nm or more. On the other hand, the thickness of the coating layer may be, for example, 100 nm or less, 50 nm or less, or 30 nm or less. The average thickness of the coating layer may be measured, for example, using a transmission electron microscope (TEM). Specifically, the thickness of any portion may be measured by obtaining a cross-sectional SEM image of the coated sulfide solid electrolyte, and the average value may be calculated to obtain the average thickness.

[0085] The coating layer has no particular limitation on its coverage as long as it covers at least a portion of the surface of the sulfide solid electrolyte, but preferably has a higher coverage. The coverage is, for example, 50% or more, 70% or more, or 80% or more. On the other hand, the coverage is, for example, 100% or less, 95% or less, or 90% or less. The coverage can be determined by X-ray photoelectron spectroscopy (XPS).

[0086] (3) Coated sulfide solid electrolyte

[0087] From the viewpoint of suppressing battery resistance, in the coated sulfide solid electrolyte, the ratio of the above-mentioned modifier is preferably 12.5% ​​by mass or less relative to the above-mentioned sulfide solid electrolyte. The ratio of the modifier may be 10.0% by mass or less, and may be 8.0% by mass or less. On the other hand, the ratio of the modifier is, for example, 1.0% by mass or more, 2.5% by mass or more, 3.0% by mass or more, and 5.0% by mass or more.

[0088] As shown in the examples described later, when a coating layer is provided, the water resistance (resistance increase rate) of the solid battery becomes significantly better than that without a coating layer (Comparative Examples 1 to 3). Specifically, the rate of increase of the battery resistance caused by the exposure time is significantly reduced. On the other hand, although the reason is uncertain, it is confirmed that the greater the proportion of the modifier, the greater the battery resistance. Therefore, from the viewpoint of suppressing the battery resistance, it is preferred that the proportion of the modifier is low.

[0089] 2. Positive electrode active material layer

[0090] The positive electrode active material layer in the present disclosure contains at least a positive electrode active material. In addition, the positive electrode active material layer contains the above-mentioned coated sulfide solid electrolyte as an electrolyte. The coated sulfide solid electrolyte is the same as that described in "1. Coated sulfide solid electrolyte", so the description here is omitted.

[0091] Examples of the positive electrode active material include oxide active materials. Examples of the oxide active material include LiCoO 2 、LiMnO 2 、LiNiO 2 、LiVO 2 and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2 Rock salt layered active materials such as LiMn 2 O 4 , Li 4 Ti 5 O 12 and Li(Ni 0.5 Mn1.5 ) 4 Spinel active materials such as LiFePO 4 、LiMnPO 4 、LiNiPO 4 and LiCoPO 4 As the positive electrode active material, sulfur (S) can be used.

[0092] In addition, the surface of the positive electrode active material may be LiNbO 3 The thickness of the Li ion conductive oxide is, for example, not less than 1 nm and not more than 30 nm.

[0093] The shape of the positive electrode active material is, for example, a particle shape. The average particle size (D 50 ) is not particularly limited, and is, for example, 10 nm or more and 50 μm or less. 50 ), as described above.

[0094] In addition, as required, the positive electrode active material layer may contain at least one of a conductive aid and a binder. As a conductive aid, for example, a carbon material can be listed. As a carbon material, for example, artificial graphite, graphite carbon fiber, resin calcined carbon, thermal decomposition vapor-grown carbon, coke, mesophase carbon microbeads, furfuryl alcohol resin calcined carbon, polyphenylene, asphalt-based carbon fiber, vapor-grown carbon fiber, natural graphite, and difficult graphitization carbon can be listed. As a binder, for example, fluorine-based polymers such as polytetrafluoroethylene and polyvinylidene fluoride; thermoplastic elastomers such as butene rubber and styrene butadiene rubber; and various resins such as acrylic resins, acrylic polyol resins, polyvinyl acetal resins, polyvinyl butyral resins, and silicone resins.

[0095] In addition, the positive electrode active material layer may contain only the above-mentioned coated sulfide solid electrolyte as an electrolyte. On the other hand, the positive electrode active material layer may contain an electrolyte (other electrolyte) other than the above-mentioned coated sulfide solid electrolyte as an electrolyte. As other electrolytes, inorganic solid electrolytes such as oxide solid electrolytes and halide solid electrolytes can be listed. The oxide solid electrolyte preferably contains oxygen (O) as the main component of the anion element. The halide solid electrolyte preferably contains a halogen as the main component of the anion. In addition, the positive electrode active material layer may contain the above-mentioned sulfide solid electrolyte (sulfide solid electrolyte without a coating layer) as another electrolyte.

[0096] When the positive electrode active material layer contains an electrolyte other than the above-mentioned coated sulfide solid electrolyte, the ratio of the coated sulfide solid electrolyte to the total electrolyte is, for example, 50% by mass or more, 70% by mass or more, or 90% by mass or more. On the other hand, the ratio of the coated sulfide solid electrolyte to the total electrolyte is, for example, 99% by mass or less, or 95% by mass or less.

[0097] The thickness of the positive electrode active material layer is not particularly limited, and is, for example, 0.1 μm or more and 1000 μm or less.

[0098] 3. Negative electrode active material layer

[0099] The negative electrode active material layer in the present disclosure contains at least a negative electrode active material. In addition, the negative electrode active material layer contains the above-mentioned coated sulfide solid electrolyte as an electrolyte. The coated sulfide solid electrolyte is the same as that described in "1. Coated sulfide solid electrolyte", so the description here is omitted.

[0100] As the negative electrode active material, for example, Si-based active materials, carbon-based active materials, and Li-based active materials can be listed. Si-based active materials are active materials containing Si elements. For example, Si-based active materials can include Si single substance, Si alloy, and Si oxide. Si alloy preferably contains Si element as the main component. The proportion of Si element in Si alloy is, for example, 50 mol% or more and 99 mol% or less. As Si alloys, for example, Si-Al alloys, Si-Sn alloys, Si-In alloys, Si-Ag alloys, Si-Pb alloys, Si-Sb alloys, Si-Bi alloys, Si-Mg alloys, Si-Ca alloys, Si-Ge alloys, Si-Pb alloys, etc. can be listed. Si alloys can be two-component alloys or three-component or more multi-component alloys. As Si oxides, for example, SiO can be listed.

[0101] The carbon-based active material is an inorganic active material containing the element C, and examples thereof include graphite, hard carbon, and soft carbon. In addition, the Li-based active material is an active material containing the element Li, and examples thereof include simple Li and Li alloys.

[0102] The shape of the negative electrode active material may be, for example, a particle shape or a layer shape. The average particle size (D 50 ) is, for example, 10 nm or more and 50 μm or less. 50 ), as described above.

[0103] In addition, the negative electrode active material layer may contain at least one of a conductive aid and a binder as required. In addition, the negative electrode active material layer may contain an electrolyte other than the above-mentioned coated sulfide solid electrolyte as an electrolyte. The conductive aid, binder and electrolyte are the same as those described in "2. Positive electrode active material layer".

[0104] The thickness of the negative electrode active material layer is not particularly limited, and is, for example, 0.1 μm or more and 1000 μm or less.

[0105] 4. Solid electrolyte layer

[0106] The solid electrolyte layer in the present disclosure is a layer disposed between the positive electrode active material layer and the negative electrode active material layer. In addition, the solid electrolyte layer contains the above-mentioned coated sulfide solid electrolyte as an electrolyte. The coated sulfide solid electrolyte is the same as that described in "1. Coated sulfide solid electrolyte", so the description here is omitted.

[0107] In addition, the solid electrolyte layer may contain a binder as required. The binder is the same as described in "2. Positive electrode active material layer". In addition, the solid electrolyte layer may contain an electrolyte other than the above-mentioned coated sulfide solid electrolyte as an electrolyte. The electrolyte is the same as described in "2. Positive electrode active material layer".

[0108] The thickness of the solid electrolyte layer is not particularly limited, and is, for example, 0.1 μm or more and 1000 μm or less.

[0109] 5. Solid-state batteries

[0110] The solid battery in the present disclosure generally comprises: a positive electrode current collector for collecting electrons of the positive electrode active material layer and a negative electrode current collector for collecting electrons of the negative electrode active material layer. Examples of materials for the positive electrode current collector include SUS, aluminum, nickel, iron, titanium, and carbon. On the other hand, examples of materials for the negative electrode current collector include SUS, copper, nickel, and carbon.

[0111] In addition, the solid battery in the present disclosure may include an outer packaging body for housing the above-mentioned components. As the outer packaging body, for example, a laminated outer packaging body and a shell-type outer packaging body can be listed. In addition, the solid battery in the present disclosure may include a constraint fixture that gives a constraint pressure in the thickness direction to the above-mentioned components. As a constraint fixture, a known fixture can be used. The constraint pressure is, for example, greater than 0.1MPa and less than 50MPa, and can be greater than 1MPa and less than 20MPa.

[0112] The type of solid battery in the present disclosure is not particularly limited, typically a lithium ion secondary battery. The use of the solid battery is not particularly limited, for example, the power supply of vehicles such as hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), electric vehicles (BEV), gasoline vehicles, and diesel vehicles can be listed. It is particularly preferred to be used as a driving power supply for hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV) or electric vehicles (BEV). In addition, the solid battery in the present disclosure can be used as a power supply for mobile bodies other than vehicles (such as railways, ships, aircraft), and can also be used as a power supply for electrical products such as information processing devices.

[0113] B. Method for manufacturing solid state battery

[0114] In addition, the present disclosure can also provide a method for manufacturing a solid battery, which is a method for manufacturing the above-mentioned solid battery, comprising: a preparation step of preparing the coated sulfide solid electrolyte; and a layer formation step of forming the positive electrode active material layer, the negative electrode active material layer and the solid electrolyte layer using the coated sulfide solid electrolyte, wherein the layer formation step is performed in an environment with a dew point temperature of -50°C or above.

[0115] 1. Preparation process

[0116] The preparation step is a step of preparing the above-mentioned coated sulfide solid electrolyte. In the preparation step, the above-mentioned coated sulfide solid electrolyte may be purchased for preparation or may be prepared by itself. The coated sulfide solid electrolyte may be prepared, for example, as follows.

[0117] First, a compound containing a Li element, a compound containing a S element, and a compound containing a P element are mixed in an arbitrary ratio to obtain a raw material composition. In addition, the raw material composition may contain a compound containing a halogen element.

[0118] Examples of compounds containing the Li element include Li 2 Li sulfides such as S and Li 2 Examples of compounds containing the element P include simple substance P, P 2 O 5 Oxides of P, and P 2 S 5 The compound containing the S element may be a simple substance (S) and a sulfide. Examples of the compound containing a halogen element include lithium halides such as LiF and LiCl.

[0119] Next, the raw material composition is mixed with a complexing agent such as tetramethylethylenediamine and dried. Thus, an amorphous sulfide solid electrolyte can be prepared. By mixing with the complexing agent, the modifier described later becomes more easily attached to the surface of the sulfide solid electrolyte. In addition, by calcining the amorphous sulfide solid electrolyte at a temperature above the crystallization temperature, a crystalline sulfide solid electrolyte can be prepared.

[0120] Then, the coating layer is formed on the surface of the sulfide solid electrolyte using the above-mentioned modifier. Thus, a coated sulfide solid electrolyte can be prepared. The coating layer can be formed by mixing the sulfide solid electrolyte, the above-mentioned modifier, and a solvent such as toluene and drying.

[0121] 2. Layer formation process

[0122] The layer forming step is a step of forming the positive electrode active material layer, the negative electrode active material layer and the solid electrolyte layer using the coated sulfide solid electrolyte. In particular, in the method for manufacturing a solid battery in the present disclosure, the layer forming step is performed in an environment with a dew point temperature of -50°C or higher.

[0123] In order to avoid reaction with moisture in the air, sulfide solid electrolytes are preferably used in an environment with a sufficiently low moisture content. In this regard, it takes cost to maintain such an environment. The coated sulfide solid electrolyte in the present disclosure improves water resistance by using a coating layer, so it can also be used in an environment with a relatively high moisture content. As a result, the manufacturing cost of the solid battery can be reduced.

[0124] The dew point temperature is not particularly limited as long as it is -50°C or higher. The dew point temperature may be -45°C or higher, -40°C or higher, or -35°C or higher. On the other hand, the dew point temperature is, for example, -30°C or lower.

[0125] The above-mentioned layers can be formed, for example, by a coating method using a slurry containing the above-mentioned coated sulfide solid electrolyte.

[0126] 3. Solid-state batteries

[0127] The solid battery manufactured by the above-mentioned process is the same as that described in "A. Solid battery", and therefore the description here is omitted.

[0128] The present disclosure is not limited to the above-mentioned embodiments. The above-mentioned embodiments are illustrative only, and any embodiment having substantially the same configuration and achieving the same function and effect as the technical concept described in the patent claims of the present disclosure is included in the technical scope of the present disclosure.

[0129] Example

[0130] [Example 1]

[0131] <Production of modified sulfide solid electrolyte (coated sulfide solid electrolyte)>

[0132] Under a nitrogen atmosphere, 0.59 g of lithium sulfide, 0.95 g of phosphorus pentasulfide, 0.19 g of lithium bromide and 0.28 g of lithium iodide were introduced into a Schlenk bottle (capacity: 100 mL) with a stirrer. After rotating the stirrer, 20 mL of the complexing agent tetramethylethylenediamine (TMEDA) was added and stirring was continued for 12 hours. Thus, a complex-containing substance was obtained. The complex-containing substance was dried under vacuum at room temperature (23°C) to obtain a powder of the complex. The powder of the complex was heated at 120°C under vacuum for 2 hours to obtain an amorphous sulfide solid electrolyte.

[0133] The amorphous sulfide solid electrolyte was heated at 140° C. for 2 hours under vacuum to obtain a crystalline sulfide solid electrolyte.

[0134] Under a nitrogen atmosphere, 3 g of a crystalline sulfide solid electrolyte and 22 g of toluene were added to a Schlenk bottle (capacity: 100 mL) with a stirrer and stirred. Thus, a slurry was obtained. 0.075 g of a modifier (epoxide compound) was added to the slurry and stirred for 10 minutes. Then, the slurry was vacuum dried to remove the toluene. Thus, a modified sulfide solid electrolyte was obtained. For the epoxy compound, 1,1,1,3,5,5,5-heptamethyl-3-(3-glycidyloxypropyl)trisiloxane was used. In addition, the epoxy compound is referred to as modifier α. In addition, modifier α is equivalent to the above-mentioned compound C. In addition, the amount of epoxy compound added is an amount of 2.5 parts by mass relative to 100 parts by mass of the crystalline sulfide solid electrolyte. In addition, the modified sulfide solid electrolyte is produced and stored in an environment with sufficiently low humidity such as a dew point of -70°C.

[0135] <Production of positive electrode>

[0136] The positive electrode active material (LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O 2) 80.0g, 9.51g of the above-mentioned modified sulfide solid electrolyte, and 2.5g of a conductive aid (VGCF; manufactured by Showa Denko K.K.) were collected in a Filmix container. Then, a binder solution (a solution containing styrene butadiene rubber) and 32.21g of a solvent (tetralin) were added to the Filmix container. Thus, a positive electrode raw material composition having a solid content concentration of 69% by mass was obtained. Furthermore, the concentration of styrene butadiene rubber in the binder solution was 5% by mass relative to the entire solution. The positive electrode raw material composition was kneaded using a mixing device (Filmix) to obtain a positive electrode composition. The positive electrode composition was applied to the surface of the positive electrode collector (Al foil) in a film-like state using a blade coating method using a coater and heated at 100°C for 30 minutes. Thus, a positive electrode having a positive electrode collector and a positive electrode active material layer was obtained.

[0137] <Production of negative electrode layer>

[0138] 18.6 g of negative electrode active material (Si single substance), 8.69 g of the above-mentioned modified sulfide solid electrolyte, a binder solution (a solution containing styrene butadiene rubber) and a solvent (diisobutyl ketone) were added to a Filmix container. Thus, a raw material composition for a negative electrode having a solid content concentration of 43% by mass was obtained. Furthermore, the concentration of styrene butadiene rubber in the binder solution was 5% by mass relative to the entire solution. The raw material composition for the negative electrode was kneaded using a mixing device (Filmix) to obtain a negative electrode composition. Furthermore, the kneading was carried out using a high shear PC wheel at a peripheral speed of 5 m / s to 30 m / s. On both sides of the negative electrode collector (Ni foil), the negative electrode composition was applied in a film-like state using a doctor blade coating method using a coater and heated at 100°C for 30 minutes. Thus, a negative electrode having a negative electrode active material layer arranged on both sides of the negative electrode collector was obtained.

[0139] <Production of transfer member>

[0140] The above-mentioned modified sulfide solid electrolyte 40g, binder solution (a solution containing acrylate butadiene rubber and hexane) 8.00g, heptane 25.62g and dibutyl ether 8.00g were mixed and kneaded using an ultrasonic homogenizer. Thus, a solid electrolyte layer composition was obtained. In addition, the concentration of acrylate butadiene rubber in the binder solution was 5% by mass relative to the entire solution. On the surface of the substrate (Al foil), the solid electrolyte layer composition was applied in a film-like shape using a doctor blade coating method using an applicator and heated at 100°C for 30 minutes. Thus, a transfer member having a substrate and a solid electrolyte layer was prepared.

[0141] <Production of solid-state batteries>

[0142] The negative electrode structure was obtained by arranging the transfer member on both sides of the negative electrode in such a manner that the negative electrode active material layer was opposite to the solid electrolyte layer, and pressing was performed. Then, the positive electrode was arranged on both sides of the negative electrode structure in such a manner that the solid electrolyte layer was opposite to the positive electrode active material layer, and an electrode stack was obtained. The electrode stack was pressed using a roller press at a line pressure of 4 tons / cm. Thus, a solid battery (evaluation battery) having a solid electrolyte layer and a positive electrode arranged on both sides of the negative electrode was obtained. In addition, the design capacity of the battery is 0.3Ah.

[0143] [Example 2 and Example 3]

[0144] The prepared coated sulfide solid electrolyte was exposed to an environment with a dew point of -30°C for 3 hours or 5 hours, and then vacuum dried at 80°C for 4 hours. An evaluation cell was prepared in the same manner as in Example 1 except that the treated coated sulfide solid electrolyte was used.

[0145] [Example 4 to Example 6]

[0146] Evaluation batteries were prepared in the same manner as in Examples 1 to 3 except that 2-ethylhexyl glycidyl ether (modifier β) was used as the modifier. Note that modifier β corresponds to compound B described above.

[0147] [Example 7 to Example 9]

[0148] Evaluation batteries were prepared in the same manner as in Examples 1 to 3 except that 4-tert-butylphenyl glycidyl ether (modifier γ) was used as the modifier. Note that modifier γ corresponds to compound A described above.

[0149] [Example 10 to Example 18]

[0150] Evaluation cells were prepared in the same manner as in Examples 1 to 9, except that the amount of the modifier was changed to 5 parts by mass based on 100 parts by mass of the crystalline sulfide solid electrolyte to prepare a coated sulfide solid electrolyte.

[0151] [Example 19 to Example 27]

[0152] Evaluation cells were prepared in the same manner as in Examples 1 to 9, except that the amount of the modifier was changed to 10 parts by mass based on 100 parts by mass of the crystalline sulfide solid electrolyte to prepare a coated sulfide solid electrolyte.

[0153] [Example 28 to Example 36]

[0154] Evaluation cells were prepared in the same manner as in Examples 1 to 9 except that the amount of the modifier was changed to 15 parts by mass based on 100 parts by mass of the crystalline sulfide solid electrolyte to prepare a coated sulfide solid electrolyte.

[0155] [Example 37 to Example 45]

[0156] Evaluation cells were prepared in the same manner as in Examples 1 to 9 except that the amount of the modifier was changed to 20 parts by mass based on 100 parts by mass of the crystalline sulfide solid electrolyte to prepare a coated sulfide solid electrolyte.

[0157] [Comparative Example 1]

[0158] An evaluation cell was produced in the same manner as in Example 1, except that the crystalline sulfide solid electrolyte produced in Example 1 before the addition of the modifier was used to produce the positive electrode, the negative electrode, and the solid electrolyte layer.

[0159] [Comparative Examples 2 and 3]

[0160] The sulfide solid electrolyte in Comparative Example 1 was exposed to an environment with a dew point of -30°C for 3 hours or 5 hours, and then vacuum dried at 80°C for 4 hours. An evaluation cell was prepared in the same manner as in Comparative Example 1 except that the sulfide solid electrolyte subjected to this treatment was used.

[0161] [Evaluation 1]

[0162] <Battery resistance evaluation>

[0163] For each of the prepared evaluation batteries, charge and discharge were performed under the following conditions for 4 cycles, and the battery resistance after 4 cycles was calculated and evaluated.

[0164] Charge and discharge conditions: CCCV charge and discharge, upper limit voltage 4.25V, lower limit voltage 2.87V, 1C

[0165] In addition, the resistance increase rate due to the exposure time was calculated using the battery resistance in the case of not being exposed to the environment with a dew point temperature of -30°C as a reference. The results are shown in Tables 1 and 2.

[0166]

Table 1

[0167]

[0168] Modifier α: 1,1,1,3,5,5,5-heptamethyl-3-(3-glycidyloxypropyl)trisiloxane Modifier β: 2-ethylhexyl glycidyl ether

[0169] Modifier γ: 4-tert-butylphenyl glycidyl ether

[0170]

Table 2

[0171]

[0172] Modifier α: 1,1,1,3,5,5,5-heptamethyl-3-(3-glycidyloxypropyl)trisiloxane Modifier β: 2-ethylhexyl glycidyl ether

[0173] Modifier γ: 4-tert-butylphenyl glycidyl ether

[0174] As shown in Tables 1 and 2, all the examples suppressed the resistance increase rate compared to the comparative examples, confirming that the degradation caused by moisture in the solid battery disclosed in the present invention is suppressed. In addition, although the resistance increase rate is suppressed as the proportion of the modifier in the coated sulfide solid electrolyte increases, the battery resistance itself increases. Therefore, it is suggested that from the viewpoint of suppressing the battery resistance, it is preferable that the proportion of the modifier is smaller.

Claims

1. A solid battery comprising a positive electrode active material layer, a negative electrode active material layer, and a solid electrolyte layer disposed between the positive electrode active material layer and the negative electrode active material layer, The positive electrode active material layer, the negative electrode active material layer and the solid electrolyte layer contain a coated sulfide solid electrolyte as an electrolyte, The coated sulfide solid electrolyte comprises a sulfide solid electrolyte and a coating layer covering the surface of the sulfide solid electrolyte, the sulfide solid electrolyte contains at least Li element, S element and P element, and the coating layer contains a modifier. The modifier is at least one of a compound represented by the following general formula (1), a compound represented by the following general formula (2), a polymer of a compound represented by the following general formula (1), and a polymer of a compound represented by the following general formula (2), In formula (1), R 1 ~R 3 are each independently a hydrogen atom, a halogen atom, a monovalent hydrocarbon group or a monovalent halogenated hydrocarbon group, R 1 ~R 3 At least one of R is a monovalent hydrocarbon group or a monovalent halogenated hydrocarbon group, 1 ~R 3 at least one of which has an ether structure, In formula (2), R 11 ~R 14 are each independently a hydrogen atom, a halogen atom, a monovalent silyl ether group, a monovalent hydrocarbon group or a monovalent halogenated hydrocarbon group, R 11 ~R 14 At least one of the groups is a silyl ether group.

2. The solid battery according to claim 1, wherein: The ratio of the modifier to the sulfide solid electrolyte is 12.5 mass % or less.

3. The solid battery according to claim 1, wherein: The ratio of the modifier to the sulfide solid electrolyte is 10.0 mass % or less.

4. The solid battery according to claim 1, wherein: The modifier is at least one of a compound represented by the general formula (1) and a polymer of a compound represented by the general formula (1), R 1 ~R 3 Any two of them are hydrogen atoms, and one is a monovalent hydrocarbon group having an ether structure.

5. The solid battery according to claim 1, wherein The modifier is at least one of a compound represented by the general formula (2) and a polymer of a compound represented by the general formula (2), R 11 ~R 14 Three of them are monovalent silyl ether groups, and one is a monovalent hydrocarbon group.

6. The solid battery according to claim 1, wherein: The modifier is at least one of the following compound A, the following compound B, the following compound C, the following compound D, a polymer containing at least one of the following compound A and the following compound B, and a polymer containing at least one of the following compound C and the following compound D, 7. The solid battery according to claim 6, wherein: The modifier is the compound A, the compound B or the compound C.

8. The solid battery according to claim 1, wherein The molecular weight or weight average molecular weight of the modifier is 60 or more.

9. The solid battery according to claim 1, wherein: In the positive electrode active material layer, the negative electrode active material layer, and the solid electrolyte layer, a ratio of the coated sulfide solid electrolyte to the total of the electrolytes is 50 mass % or more and 100 mass % or less, respectively.

10. A method for manufacturing a solid battery, the method for manufacturing the solid battery according to any one of claims 1 to 9, comprising: a preparation step of preparing the coated sulfide solid electrolyte; and a layer forming step of forming the positive electrode active material layer, the negative electrode active material layer and the solid electrolyte layer using the coated sulfide solid electrolyte, in, The layer forming step is performed in an environment with a dew point temperature of -50°C or higher.

11. The method for manufacturing a solid battery according to claim 10, wherein: The layer forming step is performed in an environment with a dew point temperature of -30°C or less.

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