Electrode for solid-state batteries, and solid-state battery

Abstract

An electrode for solid-state batteries according to the present application comprises: an electrode mixture layer that contains an electrode active material and a solid electrolyte; and a current collector. The current collector includes a porous metal base material and a metal foil. The porous metal base material is integrated with the electrode mixture layer. One side of the porous metal base material is exposed from the electrode mixture layer, and the one side of the porous metal base material exposed from the electrode mixture layer is in contact with the metal foil.

Description

[Technical Field]

[0001] The present invention relates to a solid-state battery that can maintain good internal conduction and has excellent reliability, and to an electrode that can constitute the solid-state battery. [Background technology]

[0002] In recent years, with the development of portable electronic devices such as mobile phones and laptop personal computers, and the practical application of electric vehicles, there has been a growing demand for small, lightweight batteries with high capacity and high energy density.

[0003] Currently, lithium batteries, particularly lithium-ion batteries, that can meet this demand use lithium-containing composite oxides such as lithium cobalt oxide (LiCoO) and lithium nickel oxide (LiNiO) as the positive electrode active material, graphite or the like as the negative electrode active material, and an organic electrolyte solution containing an organic solvent and a lithium salt as the non-aqueous electrolyte.

[0004] As devices that use lithium-ion batteries continue to develop, there is a demand for longer life, higher capacity, and higher energy density for lithium-ion batteries, and there is also a strong demand for the safety of these longer life, higher capacity, and higher energy density lithium-ion batteries.

[0005] However, the organic electrolyte used in lithium-ion batteries contains flammable organic solvents, which can cause the organic electrolyte to generate excessive heat in the event of an abnormality such as a short circuit. Furthermore, with the recent trend toward higher energy densities in lithium-ion batteries and increasing amounts of organic solvents in organic electrolytes, greater safety is required for lithium-ion batteries.

[0006] In light of the above, solid-state batteries that use a molded body of a solid electrolyte that does not use an organic solvent instead of an organic solvent-based electrolyte are being considered. Unlike organic solvent-based electrolytes, solid-state batteries have a high level of safety because their solid electrolytes do not generate abnormal heat. Therefore, there are high expectations for them, especially in product fields that require high-capacity secondary batteries.

[0007] Furthermore, solid-state batteries are not only highly safe, but also highly reliable, environmentally resistant, and have a long lifespan, making them promising maintenance-free batteries that can contribute to social development while also continuing to contribute to safety and security.By providing solid-state batteries to society, we can contribute to achieving Goal 3 (Ensure healthy lives and promote well-being for all at all ages), Goal 7 (Ensure access to affordable, reliable, sustainable, and modern energy for all), Goal 11 (Make cities inclusive, safe, resilient, and sustainable cities and human settlements), and Goal 12 (Ensure sustainable consumption and production patterns) out of the 17 Sustainable Development Goals (SDGs) established by the United Nations.

[0008] Furthermore, further improvements in the reliability of solid-state batteries are also being considered. For example, Patent Document 1 proposes disposing a conductive porous material as a current collector for a solid-state battery between an electrode stack and the inner bottom surface of a sealed can or the inner bottom surface of an outer can. In such a solid-state battery, when a compressive force is applied in the thickness direction, for example, the conductive porous material compresses to absorb the compressive force, thereby preventing cracking of the electrodes due to the compressive force and improving reliability. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] International Publication No. 2020 / 066323 Summary of the Invention [Problem to be solved by the invention]

[0010] However, further study is needed to determine the structure of a battery that can maintain good electrical continuity when subjected to a strong impact, such as when dropped.

[0011] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a solid-state battery that can maintain good internal conductivity and has excellent reliability, and an electrode that can be used to constitute the solid-state battery. [Means for solving the problem]

[0012] The electrode for a solid battery of the present invention comprises an electrode mixture layer containing an electrode active material and a solid electrolyte, and a current collector, the current collector comprising a porous metal substrate and a metal foil, the porous metal substrate being integrated with the electrode mixture layer, one side of the porous metal substrate being exposed from the electrode mixture layer, and the one side of the porous metal substrate exposed from the electrode mixture layer being in contact with the metal foil.

[0013] The solid-state battery of the present invention includes a battery container and an electrode laminate in which a positive electrode having a current collector and a negative electrode having a current collector face each other via a solid electrolyte layer, and is characterized in that at least one of the positive electrode and the negative electrode has the solid-state battery electrode of the present invention. [Effects of the Invention]

[0014] According to the present invention, it is possible to provide a solid-state battery that can maintain good internal conduction and has excellent reliability, and an electrode that can be used to form the solid-state battery. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a cross-sectional view schematically illustrating an example of an electrode for a solid state battery according to the present invention. [Figure 2] FIG. 2 is a cross-sectional view schematically illustrating another example of an electrode for a solid state battery according to the present invention. [Figure 3] FIG. 1 is a cross-sectional view schematically illustrating an example of a solid-state battery of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] <Solid battery electrode>

[0017] The solid state battery electrode of the present invention is used as the positive electrode or negative electrode of a solid state battery (primary battery or secondary battery).

[0018] 1 and 2 are cross-sectional views schematically illustrating an example of an electrode for a solid battery. The electrode for a solid battery 10 shown in FIG. 1 has an electrode mixture layer 20 on one side of a current collector 30. The current collector 30 has a two-layer structure having a porous metal substrate 31 and a metal foil 32. The electrode mixture layer 20 is integrated with the porous metal substrate 31 of the current collector 30.

[0019] That is, the side of the electrode mixture layer 20 opposite to the side facing the solid electrolyte layer (the lower end in Figure 1) penetrates into the pores of the porous metal substrate 31 with a certain thickness and is held by the porous metal substrate 31.

[0020] 2 has electrode mixture layers 20, 20 on both sides of a current collector 30. The current collector 30 has a three-layer structure having porous metal substrates 31, 31 on both sides of a metal foil 32. Each of the two electrode mixture layers 20, 20 is integrated with the porous metal substrates 31, 31 of the current collector 30.

[0021] As shown in FIGS. 1 and 2, the electrode for a solid state battery of the present invention has a porous metal substrate and a metal foil, and the porous metal substrate and the metal foil are in contact with each other to form a current collector. The porous metal substrate is present on one or both sides of the metal foil and is integrated with an electrode mixture layer containing an electrode active material and a solid electrolyte.

[0022] Examples of materials constituting the porous metal substrate include aluminum, copper, nickel, magnesium, tin, lead, gold, and alloys thereof.

[0023] It is preferable to use a foamed metal porous body as the porous metal substrate. Specific examples of foamed metal porous bodies include "Celmet (registered trademark)" from Sumitomo Electric Industries, Ltd. It is to be noted that the thickness of such a porous metal substrate before use in the preparation of an electrode (integration with an electrode mixture layer) is usually thicker than the thickness in the electrode (thickness after integration with an electrode mixture layer). For example, the original thickness is preferably 0.1 mm or more, more preferably 0.3 mm or more, and particularly preferably 0.5 mm or more, while it is preferably 3 mm or less, more preferably 2 mm or less, and particularly preferably 1.5 mm or less.

[0024] The porosity of the porous metal substrate before being integrated with the electrode mixture layer is preferably 80% or more, more preferably 90% or more, and particularly preferably 95% or more, so that the electrode mixture can be easily filled into the pores of the porous metal substrate in the step of pressurizing the porous metal substrate and the electrode mixture, and the porous metal substrate and the electrode mixture layer can be easily integrated. On the other hand, in order to increase the amount of the substrate by a certain amount or more and to increase the conductivity, the porosity is preferably 99.5% or less, more preferably 99% or less, and particularly preferably 98.5% or less.

[0025] In order to reduce the contact resistance with the metal foil when the electrode mixture layer and the porous metal substrate are integrated, one side of the porous metal substrate (the side opposite to the electrode mixture layer side) may be exposed to the surface, rather than the entire porous metal substrate being embedded inside the electrode mixture layer. For example, by stacking the electrode mixture and the porous metal substrate and compressing them, the side of the porous metal substrate opposite to the electrode mixture layer may be exposed to the surface.

[0026] Furthermore, even if one side of the porous metal substrate is exposed on the surface, if there is no metal foil, for example, if the exposed porous metal substrate is brought into direct contact with the conductive path on the outer container side, there is a risk that conductivity will be insufficient if the battery is subjected to a strong impact, and therefore, in order to ensure a reliable conductive connection, it is necessary to form a current collector from the porous metal substrate and metal foil.

[0027] The porous metal substrate and the metal foil may simply be in contact with each other, but in order to reduce contact resistance, they are preferably integrated by pressure bonding or resistance welding.

[0028] Examples of materials constituting the metal foil include aluminum, copper, nickel, titanium, and alloys thereof (various stainless steels (SUS304, SUS316, SUS329J4L, SUS430, SUS444), various nickel alloys (HASTELLOY (registered trademark of Haynes Corporation, USA), Inconel (registered trademark of Special Metals Corporation)), titanium alloys, etc.).

[0029] In order to increase the mechanical strength of the entire current collector, the metal foil is preferably made of a material having a Vickers hardness (HV) of 200 or more, and more preferably 300 or more.

[0030] In the electrode for a solid state battery of the present invention, the above-mentioned actions of the porous metal substrate and metal foil in the current collector can maintain good internal conductivity within a battery using the electrode (solid state battery of the present invention), thereby improving reliability.

[0031] The thickness of the porous metal substrate integrated with the electrode mixture layer (when there are two porous metal substrates in contact with the electrode mixture layer as shown in Figure 2, the thickness of each porous metal substrate) is preferably 15 μm or more, more preferably 20 μm or more, from the viewpoint of better ensuring the effect of the porous metal substrate in suppressing peeling between the current collector and the electrode mixture layer. Moreover, the thickness of the porous metal substrate of the current collector is preferably 300 μm or less, more preferably 150 μm or less.

[0032] The thickness of the metal foil (when the current collector has multiple layers of metal foil, the total thickness of those layers; the same applies below) is preferably 5 μm or more, and more preferably 8 μm or more, from the viewpoint of ensuring a better current collection effect of the metal foil. However, if the metal foil is too thick, not only will the effect saturate, but the volume occupied by components not involved in power generation in the solid-state battery will increase. Therefore, the thickness of the metal foil is preferably 300 μm or less, and more preferably 150 μm or less.

[0033] The thickness of the entire current collector is preferably 20 μm or more, more preferably 25 μm or more, and is preferably 600 μm or less, and more preferably 300 μm or less.

[0034] When the solid state battery electrode is used as the positive electrode of a solid state primary battery, the electrode active material contained in the electrode mixture layer can be the same as the positive electrode active material used in conventionally known non-aqueous electrolyte primary batteries. Specifically, for example, manganese dioxide; lithium-containing manganese oxides (e.g., LiMn3O6 or composite oxides having the same crystal structure as manganese dioxide (e.g., β-type, γ-type, or a mixed structure of β-type and γ-type) and containing 3.5 mass % or less, preferably 2 mass % or less, more preferably 1.5 mass % or less, and particularly preferably 1 mass % or less); Li a Ti 5 / 3 Examples include lithium-containing composite oxides such as O4 (4 / 3≦a<7 / 3); vanadium oxide; niobium oxide; titanium oxide; sulfides such as iron disulfide; graphite fluoride; silver sulfides such as Ag2S; and nickel oxides such as NiO2.

[0035] When the solid-state battery electrode is used as the positive electrode of a solid-state secondary battery, the electrode active material to be contained in the electrode mixture layer is not particularly limited as long as it is a positive electrode active material used in conventionally known non-aqueous electrolyte secondary batteries, that is, an active material capable of absorbing and releasing Li ions. Specific examples of the positive electrode active material include LiM r Mn 2-rSpinel-type lithium manganese composite oxide represented by O4 (where M is at least one element selected from the group consisting of Li, Na, K, B, Mg, Ca, Sr, Ba, Ti, V, Cr, Zr, Fe, Co, Ni, Cu, Zn, Al, Sn, Sb, In, Nb, Ta, Mo, W, Y, Ru and Rh, and 0 ≦ r ≦ 1), Li r Mn (1-s-r) Ni s M t O (2-u) F v (where M is at least one element selected from the group consisting of Co, Mg, Al, B, Ti, V, Cr, Fe, Cu, Zn, Zr, Mo, Sn, Ca, Sr and W, 0.8 ≦ r ≦ 1.2, 0 < s < 0.5, 0 ≦ t ≦ 0.5, u + v < 1, -0.1 ≦ u ≦ 0.2, 0 ≦ v ≦ 0.1) Layered compound represented by LiCo 1-r M r O2 (where M is at least one element selected from the group consisting of Al, Mg, Ti, V, Cr, Zr, Fe, Ni, Cu, Zn, Ga, Ge, Nb, Mo, Sn, Sb and Ba, and 0 ≦ r ≦ 0.5) Lithium cobalt composite oxide represented by LiNi 1-r M r O2 (where M is at least one element selected from the group consisting of Al, Mg, Ti, Zr, Fe, Co, Cu, Zn, Ga, Ge, Nb, Mo, Sn, Sb and Ba, and 0 ≦ r ≦ 0.5) Lithium nickel composite oxide represented by Li 1+s M 1-r N r PO4F s (where M is at least one element selected from the group consisting of Fe, Mn and Co, and N is at least one element selected from the group consisting of Al, Mg, Ti, Zr, Ni, Cu, Zn, Ga, Ge, Nb, Mo, Sn, Sb, V and Ba, and 0 ≦ r ≦ 0.5, 0 ≦ s ≦ 1) Olivine-type composite oxide represented by Li2M 1-r N rExamples include pyrophosphate compounds represented by P2O7 (wherein M is at least one element selected from the group consisting of Fe, Mn, and Co, and N is at least one element selected from the group consisting of Al, Mg, Ti, Zr, Ni, Cu, Zn, Ga, Ge, Nb, Mo, Sn, Sb, V, and Ba, and 0≦r≦0.5), and any one of these may be used alone or two or more may be used in combination.

[0036] When a solid-state battery electrode is used in the positive electrode of a solid-state secondary battery, the average particle diameter of the electrode active material (positive electrode active material) is preferably 0.1 μm or more, more preferably 0.5 μm or more, and preferably 25 μm or less, more preferably 10 μm or less, from the viewpoint of reducing side reactions that cause battery capacity degradation and increasing the density of the electrode. The positive electrode active material may be primary particles or secondary particles formed by aggregation of primary particles. When the electrode mixture layer contains a solid electrolyte, using an electrode active material with an average particle diameter within the above range allows for a large interface with the solid electrolyte, thereby further improving the load characteristics of the battery.

[0037] The average particle diameter of the electrode active material and other particles (such as solid electrolytes) referred to in this specification is the 50% diameter value (D ) in the volume-based integrated fraction when determining the integrated volume from small particles using a particle size distribution analyzer (such as the Microtrac particle size distribution analyzer "HRA9320" manufactured by Nikkiso Co., Ltd.). 50 ) means

[0038] When the solid state battery electrode is used as the negative electrode of a solid state primary battery, examples of the electrode active material contained in the electrode mixture layer include metallic lithium and lithium alloys (lithium-aluminum alloys, lithium-indium alloys, etc.).

[0039] Furthermore, when the solid-state battery electrode is used as the negative electrode of a solid-state secondary battery, the electrode active material contained in the electrode mixture layer is not particularly limited as long as it is an active material capable of absorbing and releasing lithium ions that is used in conventionally known non-aqueous electrolyte secondary batteries. For example, the negative electrode active material may be one or a mixture of two or more carbonaceous materials capable of absorbing and releasing lithium, such as graphite, pyrolytic carbons, cokes, glassy carbons, fired organic polymer compounds, mesocarbon microbeads (MCMB), and carbon fiber. An oxide may also be used as the negative electrode active material, for example, Li x Nb y TiM 6 a O [5y+4 / 2]+δ (However, M 6 is at least one element selected from the group consisting of V, Cr, Mo, Ta, Zr, Mn, Fe, Mg, B, Al, Cu, and Si, and is a composite oxide having a monoclinic crystal structure represented by 0≦x≦49, 0.5≦y<24, −5≦δ≦5, 0≦a≦0.3), titanium dioxide having an anatase structure, lithium titanate having a ramsdellite structure represented by Li2Ti3O7, Li4Ti5O 12 and spinel-type lithium-titanium composite oxides represented by the formula (1), among which one or more can be used. Simple substances, compounds, and alloys thereof containing elements such as Si, Sn, Ge, Bi, Sb, and In; compounds that can be charged and discharged at low voltages close to those of metallic lithium, such as nitrides or lithium-containing oxides containing lithium and transition metals such as Co, Ni, Mn, Fe, Cr, Ti, and W; or metallic lithium or lithium alloys (such as lithium-aluminum alloys and lithium-indium alloys) can also be used as the negative electrode active material.

[0040] The electrode active material may have a reaction suppression layer on its surface to suppress a reaction between the electrode active material and the solid electrolyte. In particular, when the electrode for a solid battery is a positive electrode, it is preferable that a reaction suppression layer is provided on the surface of the electrode active material (positive electrode active material).

[0041] The reaction suppression layer may be made of any material that has ion conductivity and can suppress the reaction between the electrode active material and the solid electrolyte. Examples of materials that can form the reaction suppression layer include oxides containing Li and at least one element selected from the group consisting of Nb, P, B, Si, Ge, Ti, Zr, Ta, and W. More specifically, Nb-containing oxides such as LiNbO3, Li3PO4, Li3BO3, Li4SiO4, Li4GeO4, LiTiO3, LiZrO3, and Li2WO4 are examples. The reaction suppression layer may contain only one of these oxides, or two or more of them, or may even form a composite compound of two or more of these oxides. Among these oxides, Nb-containing oxides are preferred, and LiNbO3 is more preferred.

[0042] The reaction suppression layer is preferably present on the surface in an amount of 0.1 to 2.0 parts by mass per 100 parts by mass of the electrode active material, which allows for good suppression of the reaction between the electrode active material and the solid electrolyte.

[0043] Examples of methods for forming a reaction suppression layer on the surface of an electrode active material include the sol-gel method, mechanofusion method, CVD method, PVD method, and ALD method.

[0044] When the solid state battery electrode is a positive electrode, the content of the electrode active material (positive electrode active material) in the electrode mixture layer is preferably 20 to 95 mass %.

[0045] When the solid state battery electrode is a negative electrode, the content of the electrode active material (negative electrode active material) in the electrode mixture layer is preferably 30 to 70 mass %.

[0046] The electrode mixture layer of the solid state battery electrode may contain a conductive additive such as carbon black, graphene, etc. When the electrode mixture layer contains a conductive additive, the content of the conductive additive in the electrode mixture layer is preferably 2 to 10 mass %.

[0047] The electrode mixture layer of the solid-state battery electrode can contain a binder. Specific examples include fluororesins such as polyvinylidene fluoride (PVDF) and lithium ion conductive resins in which functional groups have been introduced into the polyethylene oxide skeleton to provide binder functionality. Note that, for example, when a sulfide-based solid electrolyte is contained in the electrode mixture layer (described below), the electrode mixture layer does not need to contain a binder if good moldability can be ensured in forming the electrode mixture layer without using a binder.

[0048] When a binder is required in the electrode mixture layer, the content is preferably 6% by mass or less, and more preferably 0.5% by mass or more. On the other hand, when good formability can be obtained without a binder, the content is preferably 0.5% by mass or less, more preferably 0.3% by mass or less, and even more preferably 0% by mass (i.e., no binder is contained).

[0049] The electrode mixture layer can contain a solid electrolyte. The solid electrolyte used in the electrode mixture layer is not particularly limited as long as it has Li-ion conductivity, and examples of the solid electrolyte that can be used include sulfide-based solid electrolytes, hydride-based solid electrolytes, halide-based solid electrolytes, and oxide-based solid electrolytes.

[0050] Examples of sulfide-based solid electrolytes include glass particles such as Li2S-P2S5, Li2S-SiS2, Li2S-P2S5-GeS2, and Li2S-B2S3. In addition, thio-LISICON type electrolytes (Li 10 GeP2S 12 , Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 Li 12-12a-b+c+6d-e M 1 3+a-b-c-d M 2 b M 3 c M 4 dM 5 12-e X e (However, M 1 is Si, Ge or Sn, M 2 is P or V, M 3 is Al, Ga, Y or Sb, M 4 is Zn, Ca, or Ba, M 5 is S, or S and O, and X is F, Cl, Br or I, 0 ≦ a < 3, 0 ≦ b + c + d ≦ 3, 0 ≦ e ≦ 3), or an argyrodite-type one [such as Li6PS5Cl, Li 7-f+g PS 6-x Cl x+y (However, 0.05 ≦ f ≦ 0.9, -3.0f + 1.8 ≦ g ≦ -3.0f + 5.7), Li 7-h PS 6-h Cl i Br j (However, h = i + j, 0 < h ≦ 1.8, 0.1 ≦ i / j ≦ 10.0), etc.] can also be used.)

[0051] Examples of the hydride-based solid electrolyte include LiBH4, a solid solution of LiBH4 and the following alkali metal compound (for example, those having a molar ratio of LiBH4 to the alkali metal compound of 1:1 to 20:1). Examples of the alkali metal compound in the solid solution include at least one selected from the group consisting of lithium halides (such as LiI, LiBr, LiF, LiCl), rubidium halides (such as RbI, RbBr, RbF, RbCl), cesium halides (such as CsI, CsBr, CsF, CsCl), lithium amide, rubidium amide, and cesium amide.)

[0052] Examples of the halide-based solid electrolyte include monoclinic LiAlCl4, defective spinel-type or layered-structured LiInBr4, monoclinic Li 6-3m Y m X6 (However, Y: yttrium, 0 < m < 2 and X = Cl or Br), etc., and in addition, for example, known ones described in International Publication No. WO2020 / 070958 and International Publication No. WO2020 / 070955 can also be used.)

[0053] Examples of oxide-based solid electrolytes include Li2O-Al2O3-SiO2-P2O5-TiO2-based glass ceramics, Li2O-Al2O3-SiO2-P2O5-GeO2-based glass ceramics, and garnet-type Li7La3Zr2O 12 , NASICON type Li 1+O Al 1+O Ti 2-O (PO4)3, Li 1+p Al 1+p Ge 2-p (PO4)3, perovskite-type Li 3q La 2 / 3-q Examples include TiO3.

[0054] Among these solid electrolytes, sulfide-based solid electrolytes are preferred due to their high Li-ion conductivity, sulfide-based solid electrolytes containing Li and P are more preferred, and argyrodite-type sulfide-based solid electrolytes are even more preferred due to their particularly high Li-ion conductivity and high chemical stability.

[0055] The average particle size of the solid electrolyte is preferably 0.1 μm or more, and more preferably 0.2 μm or more, from the viewpoint of reducing grain boundary resistance, while it is preferably 10 μm or less, and more preferably 5 μm or less, from the viewpoint of forming a sufficient contact interface between the electrode active material and the solid electrolyte.

[0056] When the solid battery electrode is a positive electrode, the content of the solid electrolyte in the electrode mixture layer is preferably 4 to 80 mass %, and when the solid battery electrode is a negative electrode, the content of the solid electrolyte in the electrode mixture layer is preferably 4 to 85 mass %.

[0057] The solid state battery electrode can be manufactured, for example, by compressing an electrode mixture prepared by mixing an electrode active material, a solid electrolyte, a conductive additive, etc., by pressure molding or the like to form a molded body of the electrode mixture, and then bonding this to a current collector by pressure bonding or the like, or by pressure molding the electrode mixture directly on the surface of the current collector to simultaneously form a molded body of the electrode mixture and bond it to the current collector. In these cases, the electrode mixture layer of the solid state battery electrode is composed of the molded body of the electrode mixture.

[0058] Alternatively, the electrode for a solid battery may be produced by mixing the electrode mixture and a solvent to prepare an electrode mixture-containing composition, applying the composition to a current collector, drying the composition, and then performing a press treatment to bond the current collector and the electrode mixture layer together, or by applying the electrode mixture-containing composition to a solid electrolyte layer that faces the electrode, drying the composition, and then placing a current collector on top of the composition and performing a press treatment to bond the current collector and the electrode mixture layer together, thereby producing an electrode for a solid battery.

[0059] It is preferable to select a solvent for the electrode mixture-containing composition that is less likely to deteriorate the solid electrolyte. In particular, sulfide-based and hydride-based solid electrolytes undergo chemical reactions with trace amounts of water, so nonpolar aprotic solvents, such as hydrocarbon solvents like hexane, heptane, octane, nonane, decane, decalin, toluene, and xylene, are preferred. Ultra-dehydrated solvents with a water content of 0.001% by mass (10 ppm) or less are particularly preferred. Fluorine-based solvents such as "Vertrel®" from DuPont-Mitsui Fluorochemicals, "Zeorolla®" from Nippon Zeon, and "Novec®" from Sumitomo 3M can also be used, as well as nonaqueous organic solvents such as dichloromethane and diethyl ether.

[0060] The thickness of the electrode mixture layer formed by pressure molding of the electrode mixture (when the electrode mixture layer is formed on both sides of the current collector, the thickness per side of the current collector; the same applies below) is usually 100 μm or more, but from the viewpoint of increasing the capacity of batteries using solid state battery electrodes, it is preferably 200 μm or more. In addition, the thickness of the electrode mixture layer formed by pressure molding of the electrode mixture is usually 3000 μm or less.

[0061] In the case of an electrode for a solid battery produced by forming an electrode mixture layer on a current collector using an electrode mixture-containing composition containing a solvent, the thickness of the electrode mixture layer is preferably 10 to 1000 μm.

[0062] <Solid battery> The solid-state battery of the present invention includes a battery container and an electrode stack in which a positive electrode having a current collector and a negative electrode having a current collector face each other via a solid electrolyte layer, and at least one of the positive electrode and the negative electrode is the electrode for the solid-state battery of the present invention. Regarding the components other than the electrode, various components employed in conventionally known solid-state batteries can be applied.

[0063] Fig. 3 shows a vertical cross-sectional view schematically illustrating an example of a solid-state battery of the present invention. The solid-state battery 100 shown in Fig. 3 has an electrode laminate 110 having a positive electrode 120, a negative electrode 130, and a solid electrolyte layer 140 interposed between them, and this electrode laminate 110 is sealed in a battery container formed by a recessed container 150 and a sealing body 160. At least one of the positive electrode 120 and the negative electrode 130 that constitute the electrode laminate 110 is an electrode for a solid-state battery of the present invention.

[0064] The positive electrode 120 has a positive electrode mixture layer 121 and a current collector 122. When the positive electrode 120 is an electrode for a solid battery of the present invention, the current collector 122 has a multilayer structure including a porous metal substrate and a metal foil, but is shown as a single layer in Fig. 3 to avoid complicating the drawing.

[0065] The negative electrode 130 has a negative electrode mixture layer 131 and a current collector 132. When the negative electrode 130 is the electrode for a solid battery of the present invention, the current collector 132 has a multilayer structure including a porous metal substrate and a metal foil, but is shown as a single layer in Fig. 3 to avoid complicating the drawing.

[0066] A recessed container 150 constituting the battery container is composed of a bottom surface portion 151 and a side wall portion 152, and has an opening portion 153 that opens to the upper side in the figure, and has a recessed cross section.

[0067] Connection terminals 180, 190 for electrically connecting the solid-state battery 100 to a device in which the solid-state battery 100 is used are provided on the lower side of the recessed container 150 in the figure. The connection terminal 180 is conductively connected to a conductive path 181 that runs from the inside of the recessed container 150 to the external connection terminal 180. The conductive path 181 is conductively connected to the positive electrode 120 of the electrode stack 110 housed in the recessed container 150, thereby establishing electrical continuity between the positive electrode 120 of the electrode stack 110 and the connection terminal 180. In the solid-state battery 100 in FIG. 3, a porous metal layer 200 for adjusting thickness is interposed between the positive electrode 120 of the electrode stack 110 and the conductive path 181.

[0068] 3 has an elastic conductive member 170, which presses the electrode laminate 110 downward in the figure. The action of this elastic conductive member 170 can improve the conductivity between the electrode laminate 110 and the porous metal layer 200 and the reliability of the electrical connection between the porous metal layer 200 and the conductive paths 181. Furthermore, when the battery does not have a porous metal layer and the electrode laminate and the conductive paths are in direct contact with each other, the elastic conductive member can improve the reliability of the electrical connection between the electrode laminate and the conductive paths.

[0069] The connection terminal portion 190 is conductively connected to a conductive path 191 that runs from the inside of the recessed container 150 to the external connection terminal portion 190, and this conductive path 191 is disposed at the top of the electrode stack 110 in the drawing and is conductively connected to the negative electrode 130 via an elastic conductive member 170 that contacts the negative electrode 130 of the electrode stack 110. This provides electrical continuity between the negative electrode 130 of the electrode stack 110 and the connection terminal portion 190.

[0070] The side wall portion 152 of the recessed container 150 has a support portion 154 that supports the elastic conductive member 170. In the solid-state battery 100 shown in Fig. 3, the support portion 154 is formed at the upper end of the inner circumferential surface of the side wall portion 152 and is a protruding portion that protrudes in the radial direction, but the support portion for holding the conductive connecting member of the solid-state battery may have any other shape as long as it can support the conductive connecting member.

[0071] Furthermore, the elastic conductive member 170 is made of, for example, a thin metal plate, and has an end provided with a locking portion 171 that corresponds to the support portion 154 of the recessed container 150. In the solid-state battery 100 shown in FIG. 3, the locking portion 171 of the elastic conductive member 170 is a hook-shaped locking piece that locks with the support portion 154. More specifically, the locking portion 171 extends from the edge of the elastic conductive member 170 toward the support portion 154 (downward in the figure), and has a tip that is folded back toward the underside of the support portion 154.

[0072] The end of the conductive path 191 is exposed on the side and bottom surfaces of the support portion 154, and the conductive path 191 and the locking portion 171 of the elastic conductive member 170 are in direct contact with each other, thereby electrically connecting the two. As a result, the elastic conductive member 170 functions as a current collector, and forms part of the conductive path that electrically connects the negative electrode 130 and the connection terminal portion 190.

[0073] When the electrode laminate is pressed by the elastic conductive member, the elastic conductive member is pressed against the current collector located on the surface of the electrode laminate facing the elastic conductive member, and the current collector located on the surface of the electrode laminate facing the conductive path (the porous metal layer) is pressed against the conductive path (the porous metal layer). If the battery vibrates in this state, the current collector and the elastic conductive member rub against each other, or the current collector and the conductive path rub against each other, the current collector is more likely to be damaged. However, when the solid battery electrode of the present invention is used, the metal foil constituting the current collector acts to prevent damage to the current collector, even in an embodiment having an elastic conductive member pressing against the electrode laminate. Therefore, the effects of the present invention are more pronounced in solid batteries having an elastic conductive member pressing against the electrode laminate.

[0074] In installing the elastic conductive member 170 in the solid-state battery 100 shown in FIG. 3 , first, the electrode stack 110 is housed inside the recessed container 150, and then the elastic conductive member 170 is placed on the upper surface of the electrode stack 110. Then, with the elastic conductive member 170 placed on the upper surface of the electrode stack 110, the tip of the locking portion 171 is positioned between the upper surface of the electrode stack 110 and the lower surface of the support portion 154 in the axial direction of the electrode stack 110 (the up-down direction in the figure). Then, while pressing the locking portion 171 of the elastic conductive member 170 toward the bottom portion 151 of the recessed container 150, the tip of the locking portion 171 is locked onto the lower surface of the support portion 154. At this time, because the locking portion 171 is pressed downward, the elastic conductive member 170 (its recess 172) bends in the opposite direction to the electrode stack 110 while in contact with the electrode stack 110. As a result, the elastic conductive member 170 presses the electrode stack 110 toward the bottom surface portion 151 of the recessed container 150 by its elastic force. In other words, the elastic conductive member 170 functions as a plate spring.

[0075] The elastic conductive member 170 has a recess 172 in contact with the upper surface of the electrode stack 110, and the bottom surface of the recess 172 is formed flat so that the electrode stack 110 can be pressed over a wider area. The elastic conductive member 170 has the function of pressing the electrode stack 110 against the inner bottom surface of the recessed container 150, and since the elastic conductive member 170 has a shape having the flat recess 172, it is possible to press the elastic conductive member 170 and the electrode stack 110 (its negative electrode 130), and the electrode stack 110 (its positive electrode 120) and the conductive path 181 (the electrode stack 110 and the porous metal layer 200, and the porous metal layer 200 and the conductive path 181) over a wider area, and electrical connection between them can be made over a wider area, which further improves the reliability of the electrical connection between the components in the solid-state battery 100.

[0076] 3, it is preferable that a gap be formed between the elastic conductive member 170 and the sealing member 160. In other words, it is preferable that the elastic conductive member 170 and the sealing member 160 are not in contact with each other. This makes it possible to avoid contact between the elastic conductive member 170 and the sealing member 160 even if the elastic conductive member 170 is pushed toward the sealing member 160 due to a change in volume of the electrode stack 110 made up of the power generating element.

[0077] In the solid-state battery 100 shown in FIG. 3, the electrode stack 110 is arranged so that the positive electrode 120 is located on the inner bottom surface side of the recessed container 150 and the negative electrode 130 is located on the sealing body 160 side (elastic conductive member 170 side), but a solid-state battery can also be configured by arranging the electrode stack so that the negative electrode is located on the inner bottom surface side of the recessed container and the positive electrode is located on the sealing body side (elastic conductive member side).

[0078] (positive electrode) The electrode for a solid state battery of the present invention can be used as the positive electrode of the solid state battery, but when the negative electrode is the electrode for a solid state battery of the present invention, a positive electrode other than the electrode for a solid state battery of the present invention can also be used. Examples of positive electrodes other than the electrode for a solid state battery of the present invention include those in which the current collector is only a metal foil or only a sheet-like conductive porous body (such as a foamed metal porous body or a porous carbon sheet).

[0079] (Negative electrode) The solid-state battery electrode of the present invention can be used as the negative electrode of the solid-state battery, but when the positive electrode is the solid-state battery electrode of the present invention, a negative electrode other than the solid-state battery electrode of the present invention can also be used. Examples of negative electrodes other than the solid-state battery electrode of the present invention include those in which the current collector is made of only a metal foil or only a sheet-like conductive porous material (such as a foamed metal porous material or a porous carbon sheet), and also include negative electrodes having a lithium sheet or a lithium alloy sheet.

[0080] In the case of a negative electrode having a lithium sheet or a lithium alloy sheet, one consisting of only this sheet or one consisting of this sheet stuck to a current collector is used.

[0081] Examples of alloying elements for lithium alloys include aluminum, lead, bismuth, indium, and gallium, with aluminum and indium being preferred. The proportion of alloying elements in the lithium alloy (the total proportion when multiple alloying elements are included) is preferably 50 atomic % or less (in this case, the remainder is lithium and inevitable impurities).

[0082] In addition, in the case of a negative electrode having a lithium alloy sheet, a laminate can be used in which a layer containing an alloying element for forming a lithium alloy is laminated on the surface of a lithium layer (a layer containing lithium) composed of a metal lithium foil or the like by pressure bonding, and this laminate is brought into contact with a solid electrolyte in a battery to form a lithium alloy on the surface of the lithium layer, thereby forming a negative electrode. In such a negative electrode, a laminate having a layer containing an alloying element on only one side of the lithium layer may be used, or a laminate having a layer containing an alloying element on both sides of the lithium layer may be used. The laminate can be formed, for example, by pressure bonding a metal lithium foil and a foil composed of an alloying element.

[0083] The current collector can also be used when a lithium alloy is formed in a battery to form a negative electrode. For example, a laminate having a lithium layer on one side of the negative electrode current collector and a layer containing an alloying element on the side of the lithium layer opposite the negative electrode current collector may be used, or a laminate having lithium layers on both sides of the negative electrode current collector and a layer containing an alloying element on the side of each lithium layer opposite the negative electrode current collector may be used. The negative electrode current collector and the lithium layer (metallic lithium foil) may be laminated by compression bonding or the like.

[0084] The layer containing the alloying elements in the laminate to be used as the negative electrode can be, for example, a foil composed of these alloying elements. The thickness of the layer containing the alloying elements is preferably 1 μm or more, more preferably 3 μm or more, and is preferably 20 μm or less, more preferably 12 μm or less.

[0085] The lithium layer of the laminate for use as a negative electrode may be, for example, a metallic lithium foil. The thickness of the lithium layer is preferably 0.1 to 1.5 mm. In addition, the thickness of the sheet for the negative electrode having a lithium or lithium alloy sheet is also preferably 0.1 to 1.5 mm.

[0086] Furthermore, when the negative electrode having a lithium sheet or a lithium alloy sheet has a current collector, the current collector can be any current collector that can be used in the solid state battery electrode of the present invention.

[0087] (solid electrolyte layer) The solid electrolyte in the solid electrolyte layer interposed between the positive electrode and the negative electrode can be one or more of the various sulfide-based solid electrolytes, hydride-based solid electrolytes, halide-based solid electrolytes, and oxide-based solid electrolytes listed above as examples of solid-state battery electrodes. However, to improve battery characteristics, it is preferable to include a sulfide-based solid electrolyte, and it is more preferable to include an argyrodite-type sulfide-based solid electrolyte. It is even more preferable to include a sulfide-based solid electrolyte in all of the positive electrode, negative electrode, and solid electrolyte layer, and it is even more preferable to include an argyrodite-type sulfide-based solid electrolyte.

[0088] The solid electrolyte layer may have a porous body such as a resin nonwoven fabric as a support.

[0089] The solid electrolyte layer can be formed by a method of compressing a solid electrolyte by pressure molding or the like; or a method of applying a solid electrolyte layer-forming composition prepared by dispersing a solid electrolyte in a solvent onto a substrate (including a porous body serving as a support), a positive electrode, or a negative electrode, drying the composition, and, if necessary, performing pressure molding such as pressing.

[0090] It is desirable to select a solvent that is unlikely to deteriorate the solid electrolyte as the solvent used in the solid electrolyte layer-forming composition, and it is preferable to use the same solvents as those exemplified above as the solvents for the electrode mixture-containing composition.

[0091] The thickness of the solid electrolyte layer is preferably 10 to 500 μm.

[0092] (electrode laminate) The positive electrode and the negative electrode can be used in a battery in the form of an electrode laminate in which a solid electrolyte layer is laminated between them, or in the form of a wound electrode body in which this electrode laminate is further wound. Furthermore, an electrode laminate formed by laminating a positive electrode, a solid electrolyte layer, and a negative electrode can be used as a unit electrode body, and multiple unit electrode bodies can be arranged in an outer casing or stacked in the thickness direction of the unit electrode bodies, and used in a solid-state battery. When multiple unit electrode bodies are used in a solid-state battery, the unit electrode bodies can be connected in series or in parallel.

[0093] When forming the electrode stack, it is preferable to pressure-mold the positive electrode, negative electrode, and solid electrolyte layer in a stacked state, from the viewpoint of increasing the mechanical strength of the electrode stack.

[0094] (Battery container) The battery container (exterior body) of the solid-state battery can have a structure as shown in Figure 3, which includes a recessed container and a sealing body, the recessed container having a conductive path connecting the inside to the outside of the recessed container, and the current collectors on the surfaces of the electrodes (positive and negative electrodes) of the electrode stack being in contact with the conductive path, thereby establishing electrical continuity between the electrodes and the conductive path. In such a battery container, the recessed container can be made of ceramics or resin. The sealing body can be made of ceramics, resin, or metal (such as an iron-based alloy, such as an iron-nickel alloy or an iron-nickel-cobalt alloy).

[0095] In the concave container, the connection terminal portion and the conductive path connecting the electrode of the electrode stack and the connection terminal portion can be made of a metal such as manganese, cobalt, nickel, copper, molybdenum, silver, palladium, tungsten, platinum, or gold, or an alloy containing these metals.

[0096] The dented container and the sealing body can be made of an insulating material (such as resin or ceramics), in which case they can be sealed by being attached to each other with an adhesive. When using an insulating dented container and a metal sealing body, as shown in Fig. 3, the sealing body side of the side wall can be made of metal by disposing a seal ring 210 made of metal (such as an iron-nickel alloy or an iron-nickel-cobalt alloy) on the sealing body 160 side of the side wall 152 of the dented container 150 (the upper side in the figure), and then the dented container and the sealing body can be welded together to seal the dented container.

[0097] In addition to the battery containers described above, various types of battery containers that have been used in various conventionally known batteries, such as cylindrical or rectangular metal containers, flat containers having an outer can and a sealed can that are used in batteries called coin-type batteries or button-type batteries, and sheet-like containers made of resin films such as metal laminate films, can be used as battery containers for solid-state batteries.

[0098] The shape of the battery container of the solid-state battery in plan view may be circular or polygonal, such as quadrilateral (square or rectangle).

[0099] <Elastic conductive material> The elastic conductive member 170 in the solid-state battery 100 shown in Fig. 3 is not particularly limited as long as it functions as a leaf spring that presses the electrode stack toward the inner bottom surface of the recessed container. Specifically, for example, as shown in Fig. 3, an elastic conductive member having a cross-sectional shape that has a locking portion 171 shaped according to the support portion 154 of the recessed container 150 and a recess 172 that presses the electrode stack 110 can be used.

[0100] The elastic conductive member can be made of a metal plate such as a stainless steel plate or a nickel-plated stainless steel plate. The thickness of the metal plate constituting the elastic conductive member is preferably 0.05 to 0.50 mm. Furthermore, when the elastic conductive member has a recess that presses the electrode laminate as shown in FIG. 3, the area of ​​the portion of the recess that contacts the electrode laminate is preferably 3 to 45 mm, from the viewpoint of enabling the elastic conductive member to press the electrode laminate more uniformly at the contact surface with the electrode laminate. 2 The depth of the recess is preferably 0.05 to 0.50 mm.

[0101] <Porous metal layer> In the case of a solid-state battery having a battery container shown in Fig. 3, a porous metal layer can be disposed between the electrode stack and the inner bottom surface of the recessed container of the battery container, thereby establishing electrical continuity between the porous metal layer and the conductive path of the recessed container. When a porous metal layer is disposed, the electrode on the inner bottom surface side of the recessed container in the electrode stack (positive electrode 120 in the case of the solid-state battery 100 shown in Fig. 3) and the conductive path of the recessed container (conductive path 181 in the case of the solid-state battery shown in Fig. 3) are electrically connected via the porous metal layer (porous metal layer 200 in the case of the solid-state battery shown in Fig. 3).

[0102] Because the porous metal layer has pores and is made of metal, it can easily undergo plastic deformation by applying force in the thickness direction. Therefore, when forming a solid-state battery, the electrode laminate can be inserted into an outer casing so as to press it against the porous metal layer (the porous metal layer that constitutes it), or the electrode laminate can be pressed against the porous metal layer (the porous metal layer that constitutes it) by the pressing force of an elastic conductive member, thereby compressively deforming the porous metal layer and improving contact between the electrode on the porous metal layer side of the electrode laminate and the current collector. When a porous metal layer is used in a solid-state battery, these effects make it possible to further reduce internal resistance.

[0103] The porous metal layer may be made of a porous body made of a metal that does not adversely affect the characteristics of the solid-state battery within the solid-state battery. However, it is preferable to use a foamed metal porous body (such as "Celmet (registered trademark)" manufactured by Sumitomo Electrochemical Industries, Ltd.) because it is relatively easy to plastically deform it.

[0104] The thickness of the porous metal layer in the solid-state battery is preferably 100 μm or more, more preferably 150 μm or more, from the viewpoint of ensuring its function better. There is no particular upper limit to the thickness of the porous metal layer in the solid-state battery, but from the viewpoint of suppressing the volume of components not involved in power generation inside the battery container, it is preferably 1500 μm or less, more preferably 1000 μm or less.

[0105] The thickness of the porous metal layer is determined from the maximum width in the thickness direction in an image of a cross section in the thickness direction observed with a scanning electron microscope (SEM) at a magnification of 50 to 1000 times.

[0106] As described above, the porous metal layer is preferably a metal porous body compressed in the thickness direction, and its thickness is preferably 90% or less, more preferably 80% or less, of the thickness of the metal porous body (such as the foamed metal porous body) used to form the porous metal layer. Therefore, the thickness of the metal porous body (such as the foamed metal porous body) used to form the porous metal layer is preferably 150 to 1000 μm.

[0107] Furthermore, the porosity of the metal porous body (such as the foamed metal porous body described above) used to form the porous metal layer is preferably 99.5% or less, more preferably 99% or less, and even more preferably 98.5% or less, from the viewpoint of facilitating plastic deformation when the electrode laminate is pressed against it and better ensuring the effect of reducing the internal resistance of the solid-state battery and the effect of suppressing its variation; and from the viewpoint of increasing the capacity of the positive electrode or negative electrode while ensuring sufficient strength for use, the porosity is preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more.

[0108] The solid-state battery of the present invention can be used in the same applications as conventionally known primary batteries and secondary batteries, but since it has a solid electrolyte instead of an organic electrolyte solution, it has excellent heat resistance and can be preferably used in applications where it is exposed to high temperatures. The electrode for a solid-state battery of the present invention can constitute the solid-state battery of the present invention. [Example]

[0109] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples.

[0110] Example 1 Lithium titanate (Li4Ti5O 12 , negative electrode active material), a sulfide-based solid electrolyte (Li6PS5Cl) having an average particle size of 0.7 μm, and graphene (conductive additive) were mixed in a mass ratio of 50:41:9 to prepare a negative electrode mixture.

[0111] In addition, a positive electrode mixture was prepared by mixing LiCoO (positive electrode active material) with an average particle size of 5 μm and a LiNbO coating layer formed on its surface, a sulfide-based solid electrolyte (LiPSCl) with an average particle size of 0.7 μm, and graphene in a mass ratio of 65:30.7:4.3.

[0112] Next, a sulfide-based solid electrolyte (Li6PS5Cl) powder having an average particle size of 0.7 μm was placed in a powder molding die and subjected to pressure molding at a surface pressure of 70 MPa using a press to form a provisionally molded layer of the solid electrolyte layer. Furthermore, the negative electrode mixture was placed on the upper surface of the provisionally molded layer of the solid electrolyte layer and pressure molding was performed at a surface pressure of 50 MPa to form a provisionally molded layer of the negative electrode on the provisionally molded layer of the solid electrolyte layer.

[0113] Next, a porous metal substrate made of an aluminum foamed metal porous body (thickness: 1000 μm) and a metal foil made of stainless steel (SUS430, thickness: 10 μm) were each cut out as current collectors, and this current collector was placed on top of the provisionally molded layer of the negative electrode formed on the provisionally molded layer of the solid electrolyte layer so that the porous metal substrate was in contact with the provisionally molded layer of the negative electrode, and so that the metal foil was in contact with the porous metal substrate. Pressure molding was then performed at a surface pressure of 300 MPa to form an integrated product of the solid electrolyte layer and the negative electrode (a negative electrode having a negative electrode mixture layer made of a molded body of the negative electrode mixture and a current collector).

[0114] Furthermore, after the mold was turned upside down, the positive electrode mixture was placed on the upper surface of the solid electrolyte layer in the mold (the surface opposite to the surface having the negative electrode), and pressure molding was performed at a surface pressure of 50 MPa, thereby forming a provisionally molded layer of the positive electrode on the solid electrolyte layer.

[0115] Next, the same porous metal substrate and metal foil used for the negative electrode were cut out as a current collector on the preformed layer of the positive electrode formed on the solid electrolyte layer, and the porous metal substrate was placed so that it was in contact with the preformed layer of the positive electrode, and the metal foil was placed so that it was in contact with the porous metal substrate, and pressure molding was performed at a surface pressure of 1400 MPa to obtain an electrode laminate including a positive electrode having a positive electrode mixture layer and a current collector. The thickness of the porous metal substrate integrated with the positive and negative electrode mixture layers was 120 μm, and the thickness of the metal foil was 10 μm.

[0116] A nickel-made porous metal foam cut to a diameter of 7.25 mm was placed on the inner bottom of a concave container (ceramic depth 2.5 mm) having a cross-sectional structure similar to that shown in FIG. 3 and made of ceramics, with a seal ring made of an iron-nickel-cobalt alloy arranged on the upper part of the side wall. The electrode laminate was then placed on top of the porous metal foam, with the positive electrode facing downwards. Furthermore, an elastic conductive member (thickness 0.3 mm) made of a stainless steel plate and having a cross-sectional shape similar to that shown in FIG. 3 (the area of ​​the contact surface with the electrode laminate in the concave portion was 10 mm) was placed on the negative electrode of the electrode laminate. 2 The elastic conductive member was placed so that the bottom of the recessed portion was in contact with the negative electrode, and the tip of its engaging portion was engaged with the underside of the support portion of the recessed container, so that the recessed portion of the elastic conductive member pressed the electrode stack toward the inner bottom surface of the recessed container. A sealing member made of an iron-nickel-cobalt alloy plate (0.1 mm thick) was then placed over the seal ring of the recessed container, and the sealing member and the recessed container (seal ring) were welded to seal the battery container, resulting in a solid secondary battery. In the resulting solid secondary battery, as described above, the elastic conductive member pressed the electrode stack toward the inner bottom surface of the recessed container, causing the electrode stack to press against the porous metal layer made of foamed porous metal. The foamed porous metal was compressed, adjusting the height from the inner bottom surface of the recessed container to the upper end of the electrode stack. The thickness of the porous metal layer in the solid secondary battery was 200 μm.

[0117] (Comparative Example 1) Except for changing the porous metal substrates of the positive and negative electrodes to nickel foamed porous metal bodies having a thickness of 1000 μm and disposing no metal foil on either the positive or negative electrode, a solid secondary battery was fabricated in the same manner as in Example 1. The thickness of the porous metal substrate integrated with the positive and negative electrode mixture layers was 124 μm.

[0118] (Comparative Example 2) A solid secondary battery was fabricated in the same manner as in Example 1, except that no porous metal substrate was used for either the positive electrode or the negative electrode, and the mixture layers of the positive electrode and the negative electrode were brought into direct contact with the stainless steel foil.

[0119] (Comparative Example 3) Except for changing the porous metal substrates of the positive and negative electrodes to 1000 μm thick aluminum porous metal foams and disposing no metal foil on either the positive or negative electrodes, a solid secondary battery was fabricated in the same manner as in Example 1. The thickness of the porous metal substrate integrated with the positive and negative electrode mixture layers was 120 μm.

[0120] The solid secondary batteries of the examples and comparative examples were subjected to the following tests.

[0121] (Charge / discharge test) The solid secondary batteries of the examples and comparative examples were subjected to constant current charging at a current value of 0.1 C until the voltage reached 2.6 V, and then constant voltage charging was performed while maintaining the voltage at 2.6 V until the current reached 0.01 C. After constant voltage charging, each battery was left without charging or discharging and the open circuit voltage was measured for 10 minutes, and then constant current discharging was performed at a current value of 0.1 C until the voltage reached 1.0 V. After that, the open circuit voltage was measured in the same manner for each battery for 1 hour, and then constant current charging was performed at a current value of 0.2 C until the voltage reached 2.6 V, and constant voltage charging was performed while maintaining the voltage at 2.6 V until the current reached 0.01 C, and the initial resistance (impedance at 1 kHz) of the battery was measured.

[0122] (Impact test) After the charge-discharge test, each battery was subjected to an acceleration of 19,600 m / s in the direction perpendicular to the stacking direction of the electrode stack (x-y direction). 2 The shock was applied 100 times, and the resistance value (impedance at 1 kHz) was measured after that.

[0123] The results of each of the above tests are shown in Table 1, along with the material of the current collector used for each electrode.

[0124] [Table 1]

[0125] As shown in Table 1, the solid secondary battery of Example 1 had excellent reliability, with the resistance value after the impact test remaining unchanged from the initial resistance value, whereas the battery of Comparative Example 2, which did not use a porous metal substrate and only had the electrode mixture layer in contact with the metal foil, had a large contact resistance between the electrode mixture layer and the current collector, and the internal resistance was high from the beginning, and the resistance value after the impact test also increased, resulting in poor reliability. Furthermore, the batteries of Comparative Examples 1 and 3, in which the electrode mixture layer and the porous metal substrate were integrated but no metal foil was used, had low initial resistance values ​​but increased resistance values ​​after the impact test, resulting in poor reliability.

[0126] The following additional embodiments are disclosed regarding the embodiments of the present application including the above-described Example 1. (Additional Embodiment 1) An electrode for a solid battery including an electrode mixture layer containing an electrode active material and a solid electrolyte, and a current collector, the current collector includes a porous metal substrate and a metal foil, the porous metal substrate is integrated with the electrode mixture layer, one side of the porous metal substrate is exposed from the electrode mixture layer, An electrode for a solid state battery, wherein one side of the porous metal substrate exposed from the electrode mixture layer is in contact with the metal foil. (Additional Form 2) The electrode for a solid state battery according to Additional Form 1, wherein the porous metal substrate and the metal foil are integrated together. (Additional Form 3) The electrode for a solid state battery according to Additional Form 1 or 2, wherein the porous metal substrate integrated with the electrode mixture layer has a thickness of 15 to 300 μm. (Additional Form 4) The electrode for a solid state battery according to Additional Form 1 or 2, wherein the porous metal substrate integrated with the electrode mixture layer has a thickness of 20 to 150 μm. (Additional Form 5) The electrode for a solid state battery according to any one of Additional Forms 1 to 4, wherein the metal foil has a thickness of 5 to 300 μm. (Additional Form 6) The electrode for a solid state battery according to any one of Additional Forms 1 to 4, wherein the metal foil has a thickness of 8 to 150 μm. (Supplementary Embodiment 7) A solid-state battery including a battery container and an electrode stack in which a positive electrode having a current collector and a negative electrode having a current collector face each other via a solid electrolyte layer, A solid state battery comprising the electrode for a solid state battery according to any one of Supplementary Forms 1 to 6 as at least one of the positive electrode and the negative electrode. (Additional Embodiment 8) The battery container has a recessed container and a sealing body, the hollow container has a bottom surface, a side wall, and an opening, and has a conductive path for a positive electrode and a conductive path for a negative electrode that lead from the inside to the outside, a current collector of the positive electrode is electrically connected to the conductive path for the positive electrode, and a current collector of the negative electrode is electrically connected to the conductive path for the negative electrode; 8. The solid-state battery according to claim 7, wherein the opening of the hollow container is covered with the sealing member. (Additional Embodiment 9) An elastic conductive member is disposed between the electrode stack and the inner bottom surface of the sealing body, 9. The solid-state battery according to claim 8, wherein the elastic conductive member is electrically connected to the conductive path for the positive electrode or the conductive path for the negative electrode, and presses the electrode stack toward the inner bottom surface of the hollow container.

[0127] The present application may be implemented in other forms than those described above. The embodiments disclosed in the present application are merely examples and are not intended to be limiting. The scope of the present application shall be interpreted in accordance with the appended claims rather than the above description, and all modifications within the scope of the claims are intended to be embraced within the scope of the claims. [Explanation of symbols]

[0128] 10, 11 Electrodes for solid-state batteries 20 Electrode mixture layer 30 Current collector 31 Porous metal substrate 32 Metal foil 100 solid state battery 110 Electrode laminate 120 positive electrode 121 Positive electrode mixture layer 122 Positive electrode current collector 130 negative electrode 131 Negative electrode mixture layer 132 Negative electrode current collector 140 Solid electrolyte layer 150 Concave container 151 Bottom part 152 Side wall 153 Opening 154 Support part 160 Sealing body 170 Elastic conductive member 171 Locking part 172 recess 180 Connection terminal 181 Conductive Path 190 Connection terminal 191 Conductive Path 200 Porous metal layer 210 Seal ring

Claims

1. An electrode for a solid state battery comprising an electrode mixture layer containing an electrode active material and a solid electrolyte, and a current collector, the current collector includes a porous metal substrate and a metal foil, the porous metal substrate is integrated with the electrode mixture layer, one side of the porous metal substrate is exposed from the electrode mixture layer, An electrode for a solid state battery, wherein one side of the porous metal substrate exposed from the electrode mixture layer is in contact with the metal foil.

2. The electrode for a solid state battery according to claim 1 , wherein the porous metal substrate and the metal foil are integrated together.

3. 2. The electrode for a solid state battery according to claim 1, wherein the thickness of the porous metal substrate integrated with the electrode mixture layer is 15 to 300 μm.

4. 2. The electrode for a solid state battery according to claim 1, wherein the metal foil has a thickness of 5 to 300 μm.

5. An electrode for a solid state battery as described in claim 1, wherein the Vickers hardness (HV) of the metal foil is 200 or more.

6. A solid-state battery including a battery container and an electrode stack in which a positive electrode having a current collector and a negative electrode having a current collector face each other via a solid electrolyte layer, A solid-state battery comprising the electrode for a solid-state battery according to any one of claims 1 to 5 as at least one of the positive electrode and the negative electrode.

7. the battery container has a recessed container and a sealing body, the hollow container has a bottom surface, a side wall, and an opening, and has a conductive path for a positive electrode and a conductive path for a negative electrode that lead from the inside to the outside, a current collector of the positive electrode is electrically connected to the conductive path for the positive electrode, and a current collector of the negative electrode is electrically connected to the conductive path for the negative electrode; The solid-state battery according to claim 6 , wherein the opening of the hollow container is covered with the sealing body.

8. an elastic conductive member is disposed between the electrode stack and the inner bottom surface of the sealing body; 8. The solid-state battery according to claim 7, wherein the elastic conductive member is electrically connected to the conductive path for the positive electrode or the conductive path for the negative electrode, and presses the electrode stack toward the inner bottom surface of the concave container.

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