All-solid-state battery

Abstract

The battery internal resistance is reduced and the timewise increase in same is prevented in an all-solid-state battery that uses a sulfide-based solid electrolyte and that uses a conductive porous sheet for connection between an electrode and a conductive path of the exterior body.　The all-solid-state battery according to the present invention comprises: an electrode laminate having a positive electrode, a negative electrode, and a solid electrolyte layer; and an exterior body in which the electrode laminate is enclosed therein. This all-solid-state battery is characterized in that: the exterior body has a conductive path leading from the inside to the outside and has a porous metal substrate between the positive electrode and / or the negative electrode and the conductive path of the exterior body; at least one of the positive electrode, the negative electrode, and the solid electrolyte layer contains a sulfide-based solid electrolyte; and the porous metal substrate is composed of an alloy containing Ni and Cr wherein the Ni content in this alloy is at least 60 mass% and the Cr content in this alloy is 0.1-40 mass%.

Description

All solid state battery

[0001] The present invention relates to an all-solid-state battery using a sulfide-based solid electrolyte.

[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, especially lithium ion batteries, that can meet this requirement use lithium cobalt oxide (LiCoO ２ ), lithium nickel oxide (LiNiO ２ ), graphite or the like is used as the negative electrode active material, and an organic electrolyte solution containing an organic solvent and a lithium salt is used as the non-aqueous electrolyte.

[0004] Furthermore, with the further development of devices to which lithium-ion batteries are applied, there is a demand for lithium-ion batteries with longer life, higher capacity, and higher energy density, as well as a high demand for the reliability of lithium-ion secondary batteries with longer life, higher capacity, and higher energy density.

[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 density in lithium-ion batteries and an increasing amount of organic solvent in the organic electrolyte, there is a growing demand for greater reliability in lithium-ion batteries.

[0006] In light of the above, all-solid-state lithium batteries (all-solid-state batteries) that do not use organic solvents are also being considered. All-solid-state lithium batteries use sheets or molded bodies of solid electrolytes that do not use organic solvents instead of conventional organic solvent-based electrolytes, and are highly reliable without the risk of abnormal heat generation by the solid electrolyte.

[0007] As the solid electrolyte, sulfide-based solid electrolytes, hydride-based solid electrolytes, halide-based solid electrolytes, oxide-based solid electrolytes, and the like have been investigated. Among these, the development of sulfide-based solid electrolytes has progressed rapidly due to their high lithium ion conductivity, and an all-solid-state battery using a sulfide-based solid electrolyte in each of the positive electrode, negative electrode, and solid electrolyte layer has also been proposed (Patent Document 1).

[0008] On the other hand, in an all-solid-state battery, it has also been proposed to place a conductive porous member between the exterior body and the electrode in order to relieve stress applied to the electrode during sealing (Patent Document 2). Patent Document 2 exemplifies a conductive porous member as a conductive porous sheet made of carbon fiber or a graphite molded body, and shows that it is possible to maintain stable function even when a solid electrolyte that is prone to react with other constituent materials in the battery, such as a sulfide-based solid electrolyte, is used.

[0009] JP 2023-022836 A International Publication No. 2020 / 66323 A

[0010] However, when a conductive porous sheet made of the carbon material is interposed between an electrode inside an exterior body and a conductive path leading from the inside to the outside of the exterior body and used to electrically connect them, it has been found that the electrical resistance becomes somewhat high, resulting in a problem that the internal resistance of the battery cannot be reduced beyond a certain level.Furthermore, when a conductive foam substrate made of copper or aluminum, as described in Patent Document 2, is used as the conductive porous sheet, it has been found that although the internal resistance of the battery can be reduced immediately after assembly, the resistance gradually increases.

[0011] The present invention aims to solve the problem of reducing the internal resistance of an all-solid-state battery that uses a sulfide-based solid electrolyte and utilizes a conductive porous sheet for electrical connection between the electrodes and the conductive paths of the exterior body, and to prevent the internal resistance from increasing over time.

[0012] The all-solid-state battery of the present invention includes an electrode laminate having a positive electrode, a negative electrode, and a solid electrolyte layer, and an exterior body that encapsulates the electrode laminate, wherein the exterior body has a conductive path that connects from the inside to the outside, and a porous metal substrate is provided between the positive electrode and / or the negative electrode and the conductive path of the exterior body, and at least one of the positive electrode, the negative electrode, and the solid electrolyte layer contains a sulfide-based solid electrolyte, and the porous metal substrate is made of an alloy containing Ni and Cr, and the Ni content in the alloy is 60 mass% or more, and the Cr content in the alloy is 0.1 mass% or more and 40 mass% or less.

[0013] According to the present invention, it is possible to provide an all-solid-state battery that contains a sulfide-based solid electrolyte, has low internal resistance, and can suppress an increase in internal resistance over time.

[0014] Fig. 2 is a cross-sectional view schematically showing an example of an all-solid-state battery of the present invention. Fig. 3 is a perspective view of a concave container of the all-solid-state battery of Fig. 1. Fig. 4 is a perspective view of an elastic conductive member of the all-solid-state battery of Fig. 1. Fig. 5 is a scanning electron microscope photograph for explaining the surface state of an electrode related to the all-solid-state battery of the present invention.

[0015] The all-solid-state battery of the present invention includes an electrode laminate having a positive electrode, a negative electrode, and a solid electrolyte layer, and an exterior housing that encapsulates the electrode laminate, the exterior housing having a conductive path that connects the inside to the outside, and at least one of the positive electrode, the negative electrode, and the solid electrolyte layer containing a sulfide-based solid electrolyte. The all-solid-state battery also includes a porous metal substrate between the exterior housing and at least one of the positive electrode and the negative electrode. That is, the all-solid-state battery includes the porous metal substrate as a conductive connecting member that electrically connects at least one of the positive electrode and the negative electrode to the conductive path of the exterior housing.

[0016] In the all-solid-state battery, the porous metal substrate is made of an alloy containing Ni (nickel) and Cr (chromium) (hereinafter, may be referred to as a "Ni-Cr alloy"), in which the Ni content in the alloy is 60% by mass or more and the Cr content in the alloy is 0.1% by mass or more and 40% by mass or less.

[0017] Since Ni has high conductivity, by using a porous metal substrate made of this to connect the electrodes and the conductive paths of the exterior body, the resistance between the electrodes and the conductive paths can be lowered, thereby reducing the internal resistance of the all-solid-state battery.

[0018] Furthermore, because the porous metal substrate has pores and is made of metal, applying force in the thickness direction makes it easy to ensure contact with the electrode. This also eliminates gaps caused by variations in the thickness (height) of individual components, ensuring a more reliable conductive connection between the electrode and the conductive path. In particular, when a foamed metal substrate is used, it can be easily plastically deformed. Therefore, when forming an all-solid-state battery, the porous metal substrate can be compressed and deformed according to the degree of variation in the thickness (height) of each component (deviation from the design value) by inserting the electrode laminate into an outer casing so as to press it against the porous metal substrate, or by pressing the electrode laminate against the porous metal substrate using the pressing force of an elastic conductive member (described later). This improves contact between the electrode laminate and the electrode pressed by the porous metal substrate, and also homogenizes the degree of conduction between the porous metal substrate and the electrode laminate in each all-solid-state battery when a large number of all-solid-state batteries are manufactured. When a porous metal substrate, particularly a foamed metal substrate, is used in an all-solid-state battery, these effects can lower the internal resistance and reduce the variation in individual internal resistances.

[0019] However, if the electrode mixture layer or solid electrolyte layer contains a sulfide-based solid electrolyte, sulfide gases such as hydrogen sulfide are generated inside the battery, and this gas may corrode the porous metal substrate, or the porous metal substrate may corrode due to direct contact with the sulfide-based solid electrolyte, which may result in an increase in the internal resistance of the battery over time.

[0020] Therefore, in the all-solid-state battery of the present invention, the electrodes and the conductive paths of the exterior body are electrically connected by a porous metal substrate made of an alloy containing Ni and Cr. The action of Cr in the porous metal substrate can suppress corrosion due to contact with the sulfide-based solid electrolyte or gas derived from the sulfide-based solid electrolyte.

[0021] On the other hand, in a porous metal substrate made of an alloy containing Ni and Cr, Cr also has the effect of decreasing the electrical conductivity and increasing the resistance.

[0022] Therefore, in the all-solid-state battery of the present invention, the Ni content and the Cr content in the Ni-Cr alloy constituting the porous metal substrate, which is the conductive connecting member, are each set within a specific range, thereby enabling good conductivity and suppression of corrosion by the sulfide-based solid electrolyte, thereby reducing the initial internal resistance and suppressing an increase in internal resistance over time.

[0023] The all-solid-state battery of the present invention includes a secondary battery (all-solid-state secondary battery) and a primary battery (all-solid-state primary battery).

[0024] A longitudinal cross-sectional view schematically illustrating an example of an all-solid-state battery of the present invention is shown in Fig. 1. The all-solid-state battery 100 shown in Fig. 1 has an electrode laminate 110 having a positive electrode 120, a negative electrode 130, and a solid electrolyte layer 140 interposed therebetween, and this electrode laminate 110 is sealed in a battery container (exterior body) formed by a recessed container 150 and a sealing body 160.

[0025] Fig. 2 is a perspective view schematically illustrating a recessed container 150 constituting the battery container of the all-solid-state battery 100 shown in Fig. 1. As shown in Fig. 2, the recessed container 150 is composed of a bottom surface portion 151 and a side wall portion 152, has an opening portion that opens to the upper side in the figure, and has a recessed cross section.

[0026] The battery 100 shown in FIG. 1 is an example having a positive electrode 120 having a sheet-like metal substrate 122 as a current collector and a negative electrode 130 having a sheet-like metal substrate 132 as a current collector. That is, the positive electrode 120 has a positive electrode mixture layer 121 and a foamed metal substrate 122 similar to that used as the conductive connecting member. The entire foamed metal substrate 122, including the end portion on the positive electrode mixture layer 121 side, is embedded in the surface layer of the positive electrode mixture layer 121. That is, the entire location of the metal substrate 122 corresponds to a region where the positive electrode mixture layer and the metal substrate coexist. Furthermore, in the positive electrode 120, the end portion of the foamed metal substrate 122 opposite the positive electrode mixture layer 121 side (the lower end portion in FIG. 1 ) is exposed. The dotted line in the positive electrode 120 indicates the boundary between the region in the positive electrode mixture layer 121 where the metal substrate does not coexist and the region where the positive electrode mixture layer and the metal substrate coexist, and corresponds to the end of the metal substrate 122 on the positive electrode mixture layer 121 side.

[0027] Similarly to the positive electrode 120, the negative electrode 130 also has a negative electrode mixture layer 131 and a foamed metal substrate 132. The entire foamed metal substrate 132, including the end on the negative electrode mixture layer 131 side, is embedded in the surface layer of the negative electrode mixture layer 131. That is, the entire location of the metal substrate 132 corresponds to the region where the negative electrode mixture layer and the metal substrate coexist. Furthermore, in the negative electrode 130, the end of the foamed metal substrate 132 on the side opposite to the negative electrode mixture layer 131 side (the upper end in FIG. 1 ) is exposed. Note that the dotted line in the negative electrode 130 indicates the boundary between the region in the negative electrode mixture layer 131 where the metal substrate does not coexist and the region where the negative electrode mixture layer and the metal substrate coexist, and corresponds to the end of the metal substrate 132 on the negative electrode mixture layer 131 side.

[0028] Connection terminals 170, 180 for electrically connecting the all-solid-state battery 100 to a device in which the all-solid-state battery 100 is used are provided on the lower side of the recessed container 150 in the figure. The connection terminal 170 is conductively connected to a conductive path 171 that runs from the inside of the recessed container 150 to the external connection terminal 170. The conductive path 171 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 170. In the all-solid-state battery 100 of FIG. 1 , a porous metal substrate 190, which serves as a conductive connecting member, is interposed between the positive electrode 120 of the electrode stack 110 and the conductive path 171. In the all-solid-state battery 100, as described above, the action of the porous metal substrate 190 increases the conductivity between the positive electrode 120 and the conductive path 171, and also makes it possible to suppress variations in the internal resistance of individual batteries when a large number of all-solid-state batteries are manufactured.

[0029] Furthermore, the connection terminal portion 180 is conductively connected to a conductive path 181 that runs from the inside of the recessed container 150 to the external connection terminal portion 180, and this conductive path 181 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 210 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 180.

[0030] The side wall portion 152 of the recessed container 150 has a support portion 153 that supports the elastic conductive member 210. In the all-solid-state battery 100, as shown in Fig. 2 , the support portion 153 is a protruding portion that is formed at the upper end of the inner circumferential surface of the side wall portion 152 and protrudes in the radial direction, but the support portion for holding the elastic conductive member of the all-solid-state battery may have another shape as long as it can support the elastic conductive member 210.

[0031] 3 is a perspective view schematically illustrating the elastic conductive member 210 included in the all-solid-state battery 100 shown in Fig. 1. The elastic conductive member 210 is made of, for example, a thin metal plate, and has a rectangular shape in plan view as shown in Fig. 3, but can have a shape corresponding to the planar shape of the electrode laminate or the concave container included in the all-solid-state battery.

[0032] The recessed container 150 of the all-solid-state battery 100 shown in FIG. 1 has a plurality of support portions 153 at the upper end of its side wall portion 152 for supporting the elastic conductive member 210. The support portions 153 are formed as protruding portions that protrude in the circumferential direction from the inner circumferential surface of the side wall portion 152. More specifically, the support portions 153 are ceiling walls of a plurality of recesses formed radially outward on the inner circumferential surface of the side wall portion 152. Portions of the conductive paths 181 are exposed on the lower surface and side surface of the ceiling walls. At least the number of support portions 153 formed corresponds to the number of supported portions 211 of the elastic conductive member 210 described below.

[0033] The elastic conductive member 210 has a supported portion 211 and a flat portion 212. A plurality of supported portions 211 are provided at radially outward locations in a plan view of the electrode stack 110 of the all-solid-state battery 101, corresponding to the positions of the supporting portions 153. The supported portions 211 are hook-shaped engaging pieces that engage with the underside of the top wall of the supporting portion 153, and extend from an edge of the elastic conductive member 210 toward the supporting portion 153 (downward in FIG. 1 ). The supported portions 211 also have a tip that is folded back toward the supporting portion 153, i.e., the underside of the top wall. The tip of the supported portion 211 contacts the conductive path 181 exposed on the underside and side surfaces of the top wall of the supporting portion 153. As a result, the elastic conductive member 210 functions as a current collector and forms part of the conductive path electrically connecting the negative electrode 130 and the connection terminal 180.

[0034] The elastic conductive member 210 is supported by a support portion 153 formed on the inner circumferential surface of the side wall portion 152 of the recessed container 150, and covers a portion of the opening of the recessed container 150. The area of ​​the elastic conductive member 210 in a plan view is smaller than the area of ​​the opening of the recessed container 150. Note that even if the hook-shaped locking piece of the elastic conductive member 210 is not locked to the underside of the top wall of the support portion 153, as long as the elastic conductive member 210 can be fixed in place with the hook-shaped locking piece pressed into a recess formed on the inner circumferential surface of the side wall portion 152, the elastic conductive member 210 is considered to be locked to the side wall portion 152 of the recessed container 150.

[0035] As shown in Figures 1 and 3, the elastic conductive member 210 has a spring portion 213 that rises from the flat portion 212 toward the negative electrode 130 of the electrode stack 110, and this spring portion 213 comes into contact with the upper surface of the negative electrode 130 of the electrode stack 110 (its current collector, the foamed metal substrate 132) in the figure, and presses the electrode stack 110 toward the inner bottom surface of the recessed container 150.

[0036] In an elastic conductive member having a spring portion, the shape of the spring portion is not particularly limited as long as it can press the electrode stack toward the inner bottom surface of the recessed container. The spring portion 213 of the elastic conductive member 210 shown in FIGS. 1 and 3 is a spring piece inclined from the planar portion 212 toward the negative electrode 130 of the electrode stack 110 (hereinafter, the spring portion 213 may be referred to as the spring piece 213). As shown in FIG. 3 , the spring piece 213 is formed by cutting out a portion of the planar portion 212 in a U-shape and is cantilevered on the planar portion 212. In other words, the spring piece 213 in the elastic conductive member 210 shown in FIGS. 1 and 3 is a leaf spring. With this type of elastic conductive member 210, it is only necessary to form the spring piece 213 on a portion of the planar portion 212, which makes it easier to manufacture the elastic conductive member and, ultimately, the all-solid-state battery. Furthermore, by forming the spring pieces 213 by cutting out the flat surface portion 212, the production of the elastic conductive member, and ultimately the production of the all-solid-state battery, can be further facilitated.

[0037] The spring piece 213 has a boundary 213a with the flat portion 212 and a tip portion 213b, and is bent at the boundary 213a and inclined from the boundary 213a to the tip portion 213b toward the electrode stack 110 in order to contact the negative electrode 130 of the electrode stack 110. However, if the tip portion 213b of the spring piece 213 is brought into contact with the negative electrode 130 of the electrode stack 110, there is a risk that the negative electrode 130 may be damaged by the tip portion 213b. Therefore, in the elastic conductive member 210 shown in Figures 1 and 3, the spring piece 213 is bent so that the tip portion 213b faces upward in Figure 2, and the spring piece 213 contacts the negative electrode 130 at a location other than the tip portion 213b.

[0038] In the elastic conductive member 210 before the all-solid-state battery 100 is assembled, the height from the bottom surface of the flat portion 212 to the point where the spring piece 213 comes into contact with the negative electrode 130 (the height of the spring piece 213) is greater than the height from the bottom surface of the flat portion 212 to the point where the spring piece 213 comes into contact with the negative electrode 130 in the elastic conductive member 210 after the all-solid-state battery 100 is assembled. This allows the spring piece 213 to press against the electrode laminate 110, and a good electrical connection between the elastic conductive member 210 and the negative electrode 130 of the electrode laminate 110 can be maintained.

[0039] Furthermore, by forming the spring portion 213 of the elastic conductive member 210 with a spring piece, it is possible to reduce the thickness of the elastic conductive member 210 excluding the supported portion 211. For example, before assembling the all-solid-state battery 100, the thickness (overall height) of the elastic conductive member 210 excluding the supported portion 211 can be the sum of the thickness of the plate material constituting the planar portion 212 and the height of the spring piece 213. Specifically, the thickness of the plate material: 0.2 mm and the height of the spring piece: 0.5 mm can be combined to make the thickness of the elastic conductive member 210 excluding the supported portion 211 0.7 mm.

[0040] Furthermore, the length (length from the boundary 213a to the tip 213b) of the spring piece 213 can be 3 mm or more, and the width (length in a direction perpendicular to the length direction) can be 1.5 mm or more. An elastic conductive member having spring pieces may have multiple spring pieces. In this case, the shapes of the spring pieces, including their width and length, may vary from one to another to prevent resonance or other reasons. The thickness of the elastic conductive member 210 excluding the supported portion 211 is preferably 1.2 mm or less, more preferably 1 mm or less, and particularly preferably 0.8 mm or less. On the other hand, in order to effectively generate a pressing force on the spring portion 213, the thickness of the elastic conductive member 210 excluding the supported portion 211 is preferably 0.3 mm or more, more preferably 0.4 mm or more, and particularly preferably 0.5 mm or more.

[0041] Furthermore, the position of the edge of the elastic conductive member 210, i.e., the supported portion 211, can be freely set in the height direction (thickness direction of the elastic conductive member 210). Therefore, even if a gap is formed between the sealing body 160 and the elastic conductive member 210, the distance between the sealing body 160 and the point where the spring piece 213 contacts the negative electrode 130 does not increase. As a result, it is possible to prevent the gap between the sealing body 160 and the electrode stack 110 from becoming large, thereby achieving a high capacity of the all-solid-state battery 100. The thickness direction of the elastic conductive member 210 is the vertical direction in FIG. 1 (height direction of the all-solid-state battery 100), and can also be said to be the direction perpendicular to the bottom surface of the flat portion 212.

[0042] The overall thickness of the elastic conductive member 210, including the supported portion 211, can be set appropriately depending on the height of the side wall portion 152 of the recessed container 150 from the bottom surface portion 151. Furthermore, the supported portion 211 only needs to have a height necessary for engagement with the supporting portion 153. The overall thickness of the elastic conductive member 210, including the supported portion 211, can be, for example, 3 mm or less, preferably 2.7 mm or less, and more preferably 2.5 mm or less.

[0043] In the elastic conductive member 210, the spring pieces 213 may be formed by cutting out the flat portion 212 as described above, or may be attached by welding the spring pieces 213 separately to the bottom surface of the flat portion 212. Alternatively, a base for attaching the spring pieces 213 may be provided in advance separately from the flat portion 212, and the spring pieces 213 may be attached to the base to form the entire spring portion. That is, the spring pieces 213 may rise directly from the flat portion 212, or may rise from the flat portion 213 via another element such as a base. Furthermore, the spring pieces 213 may be configured such that both ends of the spring pieces 213 are supported by the flat portion 212 so as to have a convex shape toward the electrode stack 110.

[0044] In installing the elastic conductive member 210 in the all-solid-state battery 100 shown in FIG. 1 , first, the electrode stack 110 is accommodated inside the recessed container 150, and then the elastic conductive member 210 is placed on the upper surface of the electrode stack 110. With the elastic conductive member 210 placed on the upper surface of the electrode stack 110, the tip of the supported portion 211 is positioned between the upper surface of the electrode stack 110 and the supporting portion 153, i.e., the lower surface of the top wall, in the axial direction of the electrode stack 110 (the up-and-down direction in FIG. 1 ). Then, while pressing the supported portion 211 of the elastic conductive member 210 toward the bottom portion 151 of the recessed container 150, the supported portion 211 is supported by the supporting portion 153. More specifically, the tip of the supported portion 211 is engaged with the supporting portion 153, i.e., the lower surface of the top wall. Because the supported portion 211 is pressed downward, the spring piece 213 of the elastic conductive member 210 is pressed in the opposite direction to the negative electrode 130 while in contact with the electrode stack 110. At this time, the spring piece 213 presses the electrode stack 110 toward the bottom portion 151 of the recessed container 150 by its elastic force. This allows the elastic conductive member 210 to make more stable contact with the electrode stack 110, preventing misalignment due to vibration or the like, and maintaining a good electrical connection.

[0045] 1 , the recessed container 150 has two support portions 153, 153, but the number of support portions 153 may be three or more. The supported portions 211 of the elastic conductive member 210 may be formed in accordance with the number of support portions 153.

[0046] In addition, an example of a method for fixing the edge (supported portion 211) of the elastic conductive member 210 to the inner surface of the side wall portion 152 of the recessed container 150 is to glue the edge of the elastic conductive member 210 to the inner surface of the side wall portion 152 of the recessed container 150.

[0047] 1 , it is preferable that a gap be formed between the elastic conductive member 210 and the sealing body 160. In other words, it is preferable that the elastic conductive member 210 and the sealing body 160 are not in contact with each other. This makes it possible to avoid contact between the elastic conductive member 210 and the sealing body 160 even if the elastic conductive member 210 is pushed toward the sealing body 160 due to a change in volume of the electrode stack 110.

[0048] In the all-solid-state battery 100 shown in FIG. 1 , the electrode laminate 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 210 side); however, an all-solid-state battery can also be configured by arranging the electrode laminate 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).

[0049] <Porous Metal Substrate> The porous metal substrate may be disposed either between the positive electrode conductive path of the outer casing and the positive electrode, or between the negative electrode conductive path of the outer casing and the negative electrode, or may be disposed in both of these positions.

[0050] As described above, the porous metal substrate is pressed against the electrode laminate and pressed against the conductive path on the inner surface of the exterior body, thereby ensuring a more reliable conductive connection between the electrode and the conductive path. Furthermore, foamed metal substrates are easily plastically deformed, which can more effectively reduce the internal resistance of the battery and suppress variations in internal resistance among multiple batteries. In this case, as in the all-solid-state battery shown in FIG. 1 , a means (an elastic conductive member in FIG. 1 ) for pressing the electrode laminate toward the inner surface of the exterior body (concave container) is preferably disposed on either the positive electrode or negative electrode side of the electrode laminate. Therefore, a typical embodiment involves a porous metal substrate being disposed between either one of the outermost electrodes (positive electrode and negative electrode) of the electrode laminate and the conductive path of the exterior body. However, depending on the internal structure of the all-solid-state battery, a porous metal substrate can also be disposed both between the conductive path for the positive electrode and the positive electrode in the exterior body, and between the conductive path for the negative electrode and the negative electrode in the exterior body.

[0051] The porous metal substrate is made of an alloy containing Ni and Cr. The Ni content in the alloy is 60% by mass or more, preferably 70% by mass or more, and more preferably 80% by mass or more, from the viewpoints of improving the conductivity of the porous metal substrate, reducing the resistance of the conductive connection between the conductive path of the exterior body and the electrode, and reducing the internal resistance of the all-solid-state battery.

[0052] Furthermore, the Cr content in the alloy is 0.1% by mass or more, preferably 3% by mass or more, and more preferably 10% by mass or more, from the viewpoint of suppressing corrosion of the porous metal substrate due to reactions with sulfide-based solid electrolytes and gases generated from the sulfide-based solid electrolytes, and suppressing an increase in the internal resistance of the all-solid-state battery over time. However, if the Cr content in the alloy is too high, the conductivity of the porous metal substrate decreases, increasing the internal resistance of the battery. Furthermore, the hardness of the porous metal substrate increases, making it difficult to plastically deform, making it difficult to adjust the variation in the thickness (height) of each component. Therefore, the Cr content in the alloy is 40% by mass or less, preferably 30% by mass or less, and more preferably 20% by mass or less.

[0053] As can be seen from the Ni content and Cr content in the alloy constituting the current collector, the composition of the alloy constituting the porous metal substrate typically contains Cr in the above-mentioned content, with the remainder being Ni, but may also contain, for example, elements other than Ni and Cr (e.g., Sn, Fe, Co, Ti, Al, Mo, etc.) in a total content of 39.9 mass% or less. That is, the composition of the alloy constituting the porous metal substrate may contain a total of 60.1 mass% or more of Ni and Cr and elements other than Ni and Cr in a range of 39.9 mass% or less.

[0054] Examples of porous metal substrates include punched metal, mesh, and expanded metal. However, it is preferable to use a foamed metal substrate made of an alloy having the above composition (such as "Celmet (registered trademark)" manufactured by Sumitomo Electric Industries, Ltd.) because it is relatively easy to plastically deform it.

[0055] The thickness of the porous metal substrate after assembly of the all-solid-state battery is preferably 20 μm or more, more preferably 100 μm or more, from the viewpoint of ensuring the function better. There is no particular upper limit to the thickness of the porous metal substrate after assembly of the all-solid-state battery, but from the viewpoint of suppressing the volume of components not involved in power generation inside the exterior body, it is preferably 500 μm or less, more preferably 300 μm or less.

[0056] The thickness of the porous metal substrate is determined by the maximum width in the thickness direction in an image of a cross section of the substrate in the thickness direction observed with a scanning electron microscope (SEM) at a magnification of 50 to 1000 times (the values ​​in the examples described later are determined by these methods).

[0057] As described above, the foam metal substrate is preferably accommodated in the battery (inside the exterior body) in a state compressed in the thickness direction, and the thickness in the battery is preferably 90% or less, and more preferably 80% or less, of the thickness before use (thickness before compression). Therefore, the thickness of the foam metal substrate before use in the battery (before compression) is preferably 100 to 3000 μm.

[0058] Furthermore, the porosity of the foamed metal substrate before use in a battery (before compression) 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 by pressing the electrode laminate against it and better ensuring the effect of reducing the internal resistance of the all-solid-state battery and the effect of suppressing variation therein; and from the viewpoint of ensuring sufficient strength for use, the porosity is preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more.

[0059] Furthermore, if the basis weight (weight per unit area) of a porous metal substrate (particularly a foamed metal substrate) is too large, the resistance or hardness increases, making it difficult to plastically deform, and there is a risk that the effect of reducing the internal resistance of the battery will be reduced. Therefore, from the viewpoint of better ensuring the effect of reducing the internal resistance of the battery, the basis weight is set to 600 g / m ２ Preferably, the weight is 400 g / m or less. ２ If the basis weight of the porous metal substrate (particularly the foamed metal substrate) is too small, the electrical resistance of the substrate increases, and the internal resistance of the battery also increases. ２ It is preferable that this is equal to or greater than this.

[0060] <Electrode Stack> The electrode stack of the all-solid-state battery has a positive electrode, a negative electrode, and a solid electrolyte layer, and the solid electrolyte layer is interposed between the positive electrode and the negative electrode.

[0061] (Positive Electrode) The positive electrode may be, for example, a molded body (pellet or the like) formed by molding a positive electrode mixture containing a positive electrode active material, or a structure having a layer formed of a positive electrode mixture (positive electrode mixture layer) on one or both sides of a current collector.

[0062] When the all-solid-state battery is a primary battery, the positive electrode active material 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 oxide (e.g., LiMn ３ O ６ or a composite oxide 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 a Li content of 3.5% by mass or less, preferably 2% by mass or less, more preferably 1.5% by mass or less, particularly preferably 1% by mass or less); ａ Ti ５／３ O ４ (4 / 3≦a<7 / 3) and other lithium-containing composite oxides; vanadium oxide; niobium oxide; titanium oxide; sulfides such as iron disulfide; graphite fluoride; Ag ２ Silver sulfides such as S; NiO ２ Nickel oxides such as:

[0063] When the all-solid-state battery is a secondary battery, the positive electrode active material can be the same as the positive electrode active material used in conventionally known non-aqueous electrolyte secondary batteries. １－ｘ M ｒ Mn ２－ｒ O ４ (wherein 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≦x≦1, 0≦r≦1), a spinel-type lithium manganese composite oxide represented by Li ｒ Mn （１－ｓ－ｔ） Ni ｓ M ｔO （２－ｕ） F ｖ (wherein 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, and 0≦r≦1.2, 0<s<0.5, 0≦t≦0.5, u+v<1, −0.1≦u≦0.2, 0≦v≦0.1), a layered compound represented by １－ｘ Co １－ｒ M ｒ O ２ (wherein 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≦x≦1, 0≦r≦0.5), lithium cobalt composite oxide represented by Li １－ｘ Ni １－ｒ M ｒ O ２ (wherein 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≦x≦1, 0≦r≦0.5), lithium nickel composite oxide represented by Li １＋ｓ－ｘ M １－ｒ N ｒ P.O. ４ F ｓ (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≦x≦1, 0≦r≦0.5, 0≦s≦1), Li ２－ｘ M １－ｒ N ｒ P ２ O ７ (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≦x≦2, 0≦r≦0.5), and the like can be exemplified by pyrophosphate compounds represented by the formula (I) (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≦x≦2, 0≦r≦0.5), and only one of these may be used, or two or more may be used in combination.

[0064] When the all-solid-state battery is a secondary battery, the average particle size of the positive electrode active material is preferably 1 μm or more, more preferably 2 μm or more, and preferably 10 μm or less, more preferably 8 μm or less. The positive electrode active material may be primary particles or secondary particles formed by aggregation of primary particles. When a positive electrode active material having an average particle size within the above range is used, a large interface with the solid electrolyte contained in the positive electrode can be secured, thereby further improving the output characteristics of the battery.

[0065] The average particle diameter of various particles (positive electrode active material, solid electrolyte, etc.) referred to in this specification is the 50% diameter value (D) in the volume-based integrated fraction when the integrated volume is calculated from particles with small particle sizes using a particle size distribution measuring device (e.g., a Microtrac particle size distribution measuring device "HRA9320" manufactured by Nikkiso Co., Ltd.). ５０ ) means

[0066] When the all-solid-state battery is a secondary battery, the positive electrode active material preferably has a reaction suppression layer on its surface to suppress reaction with the solid electrolyte contained in the electrode.

[0067] If the positive electrode active material comes into direct contact with the solid electrolyte in the molded positive electrode mixture or in the positive electrode mixture layer, the solid electrolyte may oxidize to form a resistance layer, which may reduce the ionic conductivity in the molded positive electrode mixture or in the positive electrode mixture layer. By providing a reaction suppression layer that suppresses reaction with the solid electrolyte on the surface of the positive electrode active material and preventing direct contact between the positive electrode active material and the solid electrolyte, it is possible to suppress the reduction in ionic conductivity due to oxidation of the solid electrolyte in the molded positive electrode mixture or in the positive electrode mixture layer.

[0068] The reaction suppression layer may be made of a material that has ion conductivity and can suppress the reaction between the positive 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, and Zr, more specifically, LiNbO ３ Nb-containing oxides such as Li ３ P.O. ４ , Li ３ BO ３ , Li ２SO ４ , Li ４ SiO ４ , Li ４ GeO ４ , LiTiO ３ , LiZrO ３ , Li ２ WO ４ The reaction suppression layer may contain only one of these oxides, or may contain two or more of them, or may contain a composite compound of two or more of these oxides. Among these oxides, it is preferable to use an Nb-containing oxide, such as LiNbO ３ It is more preferable to use

[0069] The reaction suppression layer is preferably present on the surface in an amount of 0.1 to 1.0 part by mass per 100 parts by mass of the positive electrode active material, which allows for effective suppression of the reaction between the positive electrode active material and the solid electrolyte.

[0070] Examples of methods for forming a reaction suppression layer on the surface of a positive electrode active material include the sol-gel method, mechanofusion method, CVD method, PVD method, and ALD method.

[0071] The content of the positive electrode active material in the positive electrode mixture is preferably 60 to 85 mass % from the viewpoint of increasing the energy density of an all-solid-state battery in which the electrode is used as a positive electrode.

[0072] The positive electrode mixture may contain a conductive additive. Specific examples thereof include carbon materials such as graphite (natural graphite, artificial graphite), graphene, carbon black, carbon nanofibers, and carbon nanotubes. ２ When S is used, conductive Ag is generated during the discharge reaction, so the conductive additive does not need to be contained. When the conductive additive is contained in the positive electrode mixture, the content thereof is preferably 1.0 part by mass or more, preferably 7.0 parts by mass or less, and more preferably 6.5 parts by mass or less, relative to 100 parts by mass of the positive electrode active material.

[0073] The positive electrode mixture may contain a binder. Specific examples include fluororesins such as polyvinylidene fluoride (PVDF). Note that, as in the case of including a sulfide-based solid electrolyte in the positive electrode mixture, if good moldability can be ensured in forming a molded body of the positive electrode mixture or a positive electrode mixture layer without using a binder, the positive electrode mixture need not contain a binder.

[0074] When a binder is required in the positive electrode mixture, the content thereof is preferably 15% by mass or less, and preferably 0.5% by mass or more. On the other hand, when moldability can be obtained without the binder in the positive electrode mixture, the content thereof 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).

[0075] The positive electrode mixture may contain a solid electrolyte. The solid electrolyte contained in the positive electrode mixture is not particularly limited as long as it has lithium ion conductivity, and examples thereof include sulfide-based solid electrolytes, hydride-based solid electrolytes, halide-based solid electrolytes, and oxide-based solid electrolytes. However, it is desirable to contain a sulfide-based solid electrolyte in the positive electrode mixture because of its high lithium ion conductivity.

[0076] The sulfide-based solid electrolyte is Li ２ S-P ２ S ５ , Li ２ S-SiS ２ , Li ２ S-P ２ S ５ -GeS ２ , Li ２ S-B ２ S ３ In addition to particles of glass, thio-LISICON type particles [Li １０ GeP ２ S １２ , Li ９．５４ Si １．７４ P １．４４ S １１．７ Cl ０．３The general formula Li12-12a-b+c+6d-eM is exemplified by １ ３＋ａ－ｂ－ｃ－ｄ M ２ ｂ M ３ ｃ M ４ ｄ M 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 either 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 one having an argyrodite-type crystal structure (argyrodite-type solid electrolyte) can also be used.

[0077] Examples of hydride-based solid electrolytes include LiBH ４ , LiBH ４ and a solid solution of the following alkali metal compound (e.g., LiBH ４ and the alkali metal compound in a molar ratio of 1:1 to 20:1. The alkali metal compound in the solid solution may be at least one selected from the group consisting of lithium halides (LiI, LiBr, LiF, LiCl, etc.), rubidium halides (RbI, RbBr, RbF, RbCl, etc.), cesium halides (CsI, CsBr, CsF, CsCl, etc.), lithium amide, rubidium amide, and cesium amide.

[0078] Examples of halide-based solid electrolytes include monoclinic LiAlCl ４ , defect spinel type or layer structure LiInBr ４ , monoclinic Li ６－３ｍ Y ｍ X ６ (wherein 0 < m < 2 and X = Cl or Br), and other known compounds described in, for example, WO 2020 / 070958 and WO 2020 / 070955 can also be used.

[0079] As the oxide-based solid electrolyte, for example, garnet-type Li ７ La ３ Zr ２ O １２ , NASICON type Li １＋Ｏ Al １＋Ｏ Ti ２－Ｏ (P.O. ４ ) ３ , Li １＋ｐ Al １＋ｐ Ge ２－ｐ (P.O. ４ ) ３ , perovskite-type Li ３ｑ La ２／３－ｑ TiO ３ Examples include:

[0080] Among these solid electrolytes, sulfide-based solid electrolytes containing Li and P are more preferred because of their high lithium ion conductivity, and argyrodite-type solid electrolytes are even more preferred because of their higher lithium ion conductivity and high chemical stability.

[0081] Examples of the argyrodite-type crystalline solid electrolyte include Li ６ P.S. ５ Particularly preferred are those represented by the following general composition formula (1), (2) or (3), such as Cl.

[0082] Li ７－ｋ P.S. ６－ｋ X ｋ (1)

[0083] In the general composition formula (1), X represents one or more halogen elements, and k satisfies 0.2<k<2.0.

[0084] Li ７－ｘ＋ｙ P.S. ６－ｘ Cl ｘ＋ｙ (2)

[0085] In the general composition formula (2), 0.05≦y≦0.9 and −3.0x+1.8≦y≦−3.0x+5.7.

[0086] Li ７－ａ P.S. ６－ａ Cl ｂ Br ｃ (3)

[0087] In the general composition formula (3), a=b+c, ​​0<a≦1.8, and 0.1≦b / c≦10.0.

[0088] 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, more preferably 5 μm or less, and particularly preferably 1 μm or less, from the viewpoint of forming a sufficient contact interface between the active material and the solid electrolyte.

[0089] From the viewpoint of further increasing ionic conductivity in the positive electrode and further improving the output characteristics of the all-solid-state battery, the content of the solid electrolyte in the positive electrode mixture is preferably 10 parts by mass or more, and more preferably 15 parts by mass or more, when the content of the positive electrode active material is 100 parts by mass. However, if the amount of solid electrolyte in the positive electrode mixture is too large, the amounts of other components may be reduced, and the effects of these components may be reduced. Therefore, the content of solid electrolyte in the positive electrode mixture is preferably 65 parts by mass or less, and more preferably 60 parts by mass or less, when the content of the positive electrode active material is 100 parts by mass.

[0090] The thickness of the positive electrode mixture molded body or the positive electrode mixture layer is preferably 0.2 mm or more, more preferably 0.5 mm or more, and even more preferably 0.7 mm or more, while it is preferably 2 mm or less, more preferably 1.7 mm or less, and even more preferably 1.5 mm or less.

[0091] A current collector can be used for the positive electrode. Examples of the positive electrode current collector include metal substrates such as metal foil, punched metal, mesh, expanded metal, and foamed metal substrates; and carbon sheets such as carbon nonwoven fabrics. The thickness of the positive electrode current collector is preferably 50 to 1500 μm. When the positive electrode current collector is made of metal, the metal is preferably one that does not react or corrode within the battery, and an alloy (Ni—Cr alloy) having the same composition as that described above for constituting the porous metal substrate is more preferred.

[0092] Among these current collectors, it is preferable to use a foamed metal substrate because it has a higher current collection efficiency. As mentioned above, examples of foamed metal substrates that can be used for the current collector include "Celmet (registered trademark)" manufactured by Sumitomo Electric Industries, Ltd. When the current collector is made of a foamed metal substrate, at least a portion of the positive electrode mixture (positive electrode mixture layer) penetrates into the pores, thereby increasing the contact area between the current collector and the positive electrode mixture layer and making it possible to further reduce the resistance of the positive electrode.

[0093] That is, the positive electrode preferably has a foam metal substrate as a current collector, and at least a portion of the positive electrode mixture is filled into the pores of the foam metal substrate. More specifically, at least a portion of the foam metal substrate serving as the positive electrode current collector, including the end portion on the positive electrode mixture layer side, is preferably embedded in the surface layer of the positive electrode mixture layer and integrated with the positive electrode mixture layer.

[0094] In addition, such a metal substrate is usually compressed and reduced in thickness when preparing a positive electrode together with a positive electrode mixture, so that the thickness before use in the positive electrode is greater than the thickness in the positive electrode. For example, the thickness of the foamed metal substrate before compression is preferably 0.1 mm or more, more preferably 0.3 mm or more, and particularly preferably 0.5 mm or more, while preferably 3 mm or less, more preferably 2 mm or less, and particularly preferably 1.5 mm or less. For example, in the method for producing an electrode laminate described below, the foamed metal substrate is compressed in the thickness direction when a positive electrode is produced through a step of pressing the positive electrode mixture and the metal substrate, and its thickness becomes the value described below.

[0095] The porosity and basis weight of the foamed metal substrate before compression may be in the same ranges as those of the conductive connecting member described above.

[0096] Furthermore, in the case of a positive electrode having a foamed metal substrate as a current collector, in which at least a portion of the metal substrate, including the end portion on the positive electrode mixture layer side, is embedded in a surface layer portion of the positive electrode mixture layer and is integrated with the positive electrode mixture layer, the thickness of the portion of the metal substrate embedded in the positive electrode mixture layer is preferably 10% or more, and more preferably 20% or more, of the thickness of the metal substrate (the thickness of the entire metal substrate, including the thickness of the portion where the positive electrode mixture layer coexists; unless otherwise specified, the same applies hereinafter to the thickness of the foamed metal substrate of the positive electrode).

[0097] In a positive electrode having a foamed metal substrate as a current collector, at least a portion of which, including the end portion on the positive electrode mixture layer side, is embedded in the surface layer portion of the positive electrode mixture layer and integrated with the positive electrode mixture layer, in order to reduce resistance when the metal substrate is in contact with a conductive path (or conductive connecting member) in the exterior body of an all-solid-state battery, it is desirable that the end portion of the metal substrate opposite the positive electrode mixture layer side (hereinafter sometimes referred to as the surface side end portion) is not embedded in the positive electrode mixture layer, and the end portion of the positive electrode (the surface of the positive electrode) is composed only of the metal substrate. That is, for example, in a manufacturing method of an electrode laminate described below, when the positive electrode is manufactured through a step of pressing the positive electrode mixture and the metal substrate, it is desirable that the metal substrate is compressed in the thickness direction, and the pores in the surface side end portion of the metal substrate are crushed and eliminated, so that only the metal substrate is exposed on the surface of the positive electrode. However, some of the pores at the surface end of the metal substrate may not be crushed and remain as pores, or may be filled with the positive electrode mixture. A portion of the mixture may be exposed to the surface of the positive electrode together with the surface end of the metal substrate, as long as it does not significantly affect the contact resistance with the conductive path. That is, as long as the surface end of the foamed metal substrate can be exposed to the electrode surface, the entire metal substrate (100% of the thickness of the metal substrate) may be embedded in the surface layer of the positive electrode mixture layer. By filling the pores of the metal substrate with the positive electrode mixture up to the surface of the positive electrode, the integration of the positive electrode mixture layer and the metal substrate can be more reliably achieved.

[0098] Fig. 4 shows an SEM photograph for explaining the surface state of an electrode having a metal substrate as a current collector (note that the SEM photograph shown in Fig. 4 is not a photograph of the surface of the positive electrode in the all-solid-state battery of the present invention, but a photograph of a positive electrode having a surface state similar to that of the positive electrode in the all-solid-state battery of the present invention, and is shown only for the purpose of explaining the surface state of the positive electrode in the all-solid-state battery of the present invention). On the surface of the positive electrode shown in Fig. 4, the end of the metal substrate 122 of the positive electrode is exposed, and part of the positive electrode mixture 121a is also exposed on the surface of the electrode by entering pores present at the end of the metal substrate.

[0099] However, since the contact resistance between the metal substrate and the conductive path (or conductive connecting member) of the exterior body increases as the proportion (area ratio) of the positive electrode mixture exposed on the surface of the positive electrode increases, the proportion of the area of ​​the exposed positive electrode mixture on the surface of the positive electrode is preferably 50% or less, more preferably 25% or less, even more preferably 15% or less, and particularly preferably 10% or less in plan view.

[0100] In a positive electrode having a metal substrate as a current collector, when at least a portion of the metal substrate is embedded in the surface layer portion of the positive electrode mixture layer, from the viewpoint of more reliably integrating the metal substrate and the positive electrode mixture layer, the thickness of the metal substrate is preferably 1% or more, more preferably 2% or more, and particularly preferably 3% or more of the total thickness of the positive electrode mixture layer (including the thickness of the portion coexisting with the metal substrate. Unless otherwise specified, the "thickness of the positive electrode mixture layer" referred to below means the "total thickness of the positive electrode mixture layer" herein.) Furthermore, from the viewpoint of improving the packing property of the positive electrode mixture layer in the positive electrode, the thickness of the metal substrate is preferably 30% or less, more preferably 20% or less, and particularly preferably 10% or less of the thickness of the positive electrode mixture layer.

[0101] In a positive electrode having a metal substrate as a current collector, the thickness of the metal substrate is preferably 10 μm or more, more preferably 20 μm or more, and particularly preferably 30 μm or more, and is preferably 300 μm or less, more preferably 200 μm or less, and particularly preferably 100 μm or less.

[0102] In the electrodes (positive and negative electrodes) referred to in this specification, the thickness of the metal substrate and the thickness of the mixture layer (positive electrode mixture layer and negative electrode mixture layer) are determined by the maximum thickness-wise width of the region where the metal substrate can be confirmed and the region where the mixture (positive electrode mixture and negative electrode mixture) can be confirmed in an image of a cross section of the electrode in the thickness direction observed with an SEM at a magnification of 50 to 1000 times. The thickness of the portion of the metal substrate embedded in the mixture layer (positive electrode mixture layer and negative electrode mixture layer) is determined by the maximum thickness-wise width of the portion where the region where the metal substrate can be confirmed and the region where the mixture can be confirmed overlap (the values ​​in the examples described below are determined by these methods).

[0103] The proportion (area ratio) of the positive electrode mixture exposed on the surface of the positive electrode can be determined by the ratio (A / B) of the total area of ​​the exposed parts of the positive electrode mixture: A to the area of ​​the entire positive electrode: B in an image of the surface of the positive electrode observed with an SEM at a magnification of 50 to 200 times (the values ​​in the examples described later are determined by this method).

[0104] The positive electrode can be manufactured by pressing a positive electrode mixture to form a molded body (such as a pellet) of the positive electrode mixture, and then bonding this to a current collector as needed; by pressing the positive electrode mixture and the current collector at the same time to mold the positive electrode mixture and integrate it with the current collector; or by a method in which a positive electrode mixture-containing composition, in which the positive electrode mixture is dispersed in a solvent, is applied to a current collector, dried, and then pressurized as needed.

[0105] The solvent for the positive electrode mixture-containing composition is preferably one that is less likely to deteriorate the solid electrolyte. In particular, sulfide-based solid electrolytes and hydride-based solid electrolytes undergo chemical reactions with trace amounts of water, so it is preferable to use nonpolar aprotic solvents, such as hydrocarbon solvents such as hexane, heptane, octane, nonane, decane, decalin, toluene, and xylene. It is particularly preferable to use an ultra-dehydrated solvent with a water content of 0.001% by mass (10 ppm) or less. Fluorine-based solvents such as "Vertrel (registered trademark)" manufactured by DuPont-Mitsui Fluorochemicals, "Zeorolla (registered trademark)" manufactured by Nippon Zeon Co., Ltd., and "Novec (registered trademark)" manufactured by Sumitomo 3M Co., Ltd., as well as nonaqueous organic solvents such as dichloromethane and diethyl ether can also be used.

[0106] The negative electrode constituting the electrode laminate may be, for example, a molded body (e.g., pellet) obtained by molding a negative electrode mixture containing a negative electrode active material, or a structure having a layer formed of the negative electrode mixture (negative electrode mixture layer) on one or both sides of a current collector. Alternatively, a negative electrode using metallic lithium or lithium-aluminum alloy foil as is, or a negative electrode having metallic lithium or lithium-aluminum alloy foil and a current collector may also be used.

[0107] Examples of the negative electrode active material in the negative electrode having the negative electrode mixture include carbon materials such as graphite, lithium titanium oxides (lithium titanate, etc.), simple substances containing elements such as Si and Sn, compounds (oxides, etc.), and alloys thereof. Lithium metal and lithium alloys (lithium-aluminum alloys, lithium-indium alloys, etc.) can also be used as the negative electrode active material.

[0108] The content of the negative electrode active material in the negative electrode mixture is preferably 40 to 80 mass % from the viewpoint of increasing the energy density of an all-solid-state battery in which the electrode is used as a negative electrode.

[0109] The negative electrode mixture may contain a conductive additive. Specific examples include the same conductive additives as those exemplified above as the conductive additives that may be contained in the positive electrode mixture. The content of the conductive additive in the negative electrode mixture is preferably 10 to 30 parts by mass, relative to 100 parts by mass of the negative electrode active material.

[0110] The negative electrode mixture may contain a binder. Specific examples thereof include the same binders as those exemplified above as binders that may be contained in the positive electrode mixture. Note that, as in the case of containing a sulfide-based solid electrolyte in the negative electrode mixture, if good moldability can be ensured in forming a molded body of the negative electrode mixture or a negative electrode mixture layer without using a binder, the negative electrode mixture need not contain a binder.

[0111] When a binder is required in the negative electrode mixture, the content thereof is preferably 15% by mass or less, and preferably 0.5% by mass or more. On the other hand, when moldability can be obtained without the binder in the negative electrode mixture, the content thereof 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).

[0112] The negative electrode mixture can contain a solid electrolyte. Examples of the solid electrolyte contained in the negative electrode mixture include the various sulfide-based solid electrolytes, hydride-based solid electrolytes, halide-based solid electrolytes, and oxide-based solid electrolytes exemplified above as those that can be contained in the positive electrode mixture. Among these solid electrolytes, sulfide-based solid electrolytes are preferred due to their high lithium ion conductivity, sulfide-based solid electrolytes containing Li and P are more preferred, and argyrodite-type solid electrolytes are even more preferred due to their higher lithium ion conductivity and chemical stability, and those represented by the general composition formula (1), the general composition formula (2), or the general composition formula (3) are particularly preferred.

[0113] For the same reasons as in the case of the positive electrode mixture, the average particle size of the solid electrolyte in the negative electrode mixture is preferably 0.1 μm or more, more preferably 0.2 μm or more, and is preferably 10 μm or less, more preferably 5 μm or less.

[0114] From the viewpoint of further increasing ionic conductivity in the negative electrode and further improving the output characteristics of the all-solid-state battery, the content of the solid electrolyte in the negative electrode mixture is preferably 30 parts by mass or more, and more preferably 35 parts by mass or more, when the content of the negative electrode active material is 100 parts by mass. However, if the amount of solid electrolyte in the negative electrode mixture is too large, the amounts of other components may be reduced, and the effects of these components may be reduced. Therefore, the content of solid electrolyte in the negative electrode mixture is preferably 130 parts by mass or less, and more preferably 110 parts by mass or less, when the content of the negative electrode active material is 100 parts by mass.

[0115] The thickness of the negative electrode mixture molded body or negative electrode mixture layer in the negative electrode is preferably 0.2 mm or more, more preferably 0.5 mm or more, and even more preferably 0.7 mm or more, while it is preferably 2 mm or less, more preferably 1.7 mm or less, and even more preferably 1.5 mm or less.

[0116] A current collector can be used for the negative electrode. Examples of the negative electrode current collector include metal substrates such as metal foil, punched metal, mesh, expanded metal, and foamed metal substrates; and carbon sheets such as carbon nonwoven fabrics. The thickness of the negative electrode current collector is preferably 50 to 1500 μm. When the negative electrode current collector is made of metal, the metal is preferably one that does not react or corrode within the battery, and an alloy (an alloy containing Ni and Cr) having the same composition as that described above for constituting the porous metal substrate is more preferred.

[0117] The current collector for the negative electrode and the negative electrode can be produced in the same manner as the current collector for the positive electrode and the positive electrode described above, and therefore detailed description thereof will be omitted.

[0118] (Solid electrolyte layer) Specific examples of the solid electrolyte constituting the solid electrolyte layer of the electrode laminate include the same solid electrolytes as those exemplified above as those that can be contained in the positive electrode mixture. Among the solid electrolytes exemplified above, it is preferable to use a sulfide-based solid electrolyte because it has high lithium ion conductivity and also has the function of improving formability, it is more preferable to use a sulfide-based solid electrolyte having an argyrodite-type crystal structure, and it is even more preferable to use one represented by the general composition formula (1), the general composition formula (2), or the general composition formula (3).

[0119] The solid electrolyte layer can be formed by a method of compressing a solid electrolyte by pressure molding or the like; a method of applying a solid electrolyte layer-forming composition prepared by dispersing a solid electrolyte in a solvent onto a substrate, a positive electrode, or a negative electrode, drying the composition, and, if necessary, performing pressure molding such as pressing.

[0120] The solid electrolyte layer may contain a binder such as an acrylic resin or a fluororesin to maintain its shape.

[0121] The solid electrolyte layer may also have a porous support such as a resin nonwoven fabric, in which case a solid electrolyte sheet having the support is obtained.

[0122] It is desirable to select a solvent for use in the solid electrolyte layer-forming composition that is less likely to deteriorate the solid electrolyte, similar to the solvent used in the positive electrode mixture-containing composition. It is preferable to use the various solvents exemplified above as the solvent for the positive electrode mixture-containing composition, and it is particularly preferable to use an ultra-dehydrated solvent with a water content of 0.001 mass % (10 ppm) or less.

[0123] The thickness of the solid electrolyte layer is preferably 10 to 200 μm.

[0124] (Method for manufacturing electrode laminate) The method for manufacturing the electrode laminate is not particularly limited, but it can be manufactured, for example, by a manufacturing method including the following steps 1 to 3. Note that the following describes the steps when a foamed metal substrate is used as the current collector.

[0125] In the first step, the mixture (positive electrode mixture or negative electrode mixture) is placed in a mold and pressure-molded. The pressure applied during pressure molding in the first step is preferably, for example, 30 to 500 MPa.

[0126] In the next step, a foamed metal substrate is placed on the mixture formed by pressure molding in step 1, and then, in step 3, the mixture and the metal substrate are pressed together. By applying pressure in step 3, the metal substrate is embedded in the mixture from the end on the mixture side, and the mixture is further compressed, and the metal substrate is compressed in the thickness direction, thereby integrating the mixture layer (positive electrode mixture layer or negative electrode mixture layer) and the metal substrate to form an electrode (positive electrode or negative electrode).

[0127] As described above, in this third step, the metal substrate is compressed in the thickness direction, and the degree of compression is, from the viewpoint of ensuring a more reliable bond between the metal substrate and the mixture layer, preferably to make the thickness of the metal substrate after compression 30% or less of the thickness before compression, more preferably 20% or less, and particularly preferably 10% or less. Furthermore, from the viewpoint of retaining a certain amount or more of the mixture in the voids of the metal substrate and increasing the bond strength between the metal substrate and the mixture layer, the thickness of the metal substrate after compression in the third step is preferably 1% or more of the thickness before compression, more preferably 2% or more.

[0128] The surface pressure during the pressurization in the third step is preferably 800 MPa or more, more preferably 1000 MPa or more, and particularly preferably 1200 MPa or more, for example, in order to compress and mold the mixture and sufficiently increase the density of the mixture layer. Although the upper limit of the surface pressure during the pressurization in the third step is not particularly specified, in a general pressurization device, the upper limit is usually about 2000 MPa.

[0129] By going through the first to third steps, an electrode (positive electrode or negative electrode) can be obtained in which at least a portion of the metal substrate, including the end portion on the mixture layer side (a certain range in the thickness direction from the end portion of the metal substrate), is embedded in the surface layer portion of the mixture layer and is integrated with the mixture layer, and the other end portion of the metal substrate is exposed on the surface of the electrode.

[0130] If the surface pressure during the application of pressure in the third step becomes too high, cracks may occur when the metal substrate is compressed. However, even if the metal substrate is broken into pieces, the ends of the pieces can contribute to reducing the contact resistance as long as they are exposed on the surface of the electrode.

[0131] The positive electrode and the negative electrode are prepared through the first, second and third steps, and are then arranged on both sides of the solid electrolyte layer, and if necessary, pressed to form an electrode stack.

[0132] Furthermore, before the first step, a preliminary step of putting the solid electrolyte into a mold and pressure-molding it may be provided, and a mixture (a positive electrode mixture or a negative electrode mixture) may be placed on the solid electrolyte pressure-molded in this preliminary step. Thereafter, the first step, the second step, and the third step may be carried out in sequence to produce an integrated product of the solid electrolyte layer and the electrode (a positive electrode or a negative electrode), which may be used in an electrode laminate.

[0133] The surface pressure during pressure molding in the preliminary step is preferably set to, for example, 30 to 120 MPa.

[0134] Alternatively, an electrode stack can be produced by forming one of a positive electrode and a negative electrode on one side of a solid electrolyte layer through the preliminary step, the first step, the second step, and the third step, and then sequentially performing the first step, the second step, and the third step on the other side of the solid electrolyte layer to form the other electrode (negative electrode or positive electrode).

[0135] <Exterior Body> As the exterior body of the all-solid-state battery, there can be used a battery container having a concave container (exterior container) and a sealing body (lid) as shown in FIG. 1; a flat (coin-shaped, button-shaped, etc.) or tubular (cylindrical, rectangular, etc.) battery container having a metal exterior can and a metal sealing body; a battery container made of a laminate film exterior body made of a metal laminate film such as an aluminum laminate film; and the like.

[0136] 1, the battery container has a recessed container and a sealing body, and 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-nickel alloy or an iron-based alloy such as an iron-nickel-cobalt alloy).

[0137] 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.

[0138] The recessed container and the sealing body can be sealed by bonding them together with an adhesive. In addition, when a metal sealing body is used, as shown in FIG. 1 , a seal ring 200 made of metal (such as an iron-nickel alloy or an iron-based alloy such as an iron-nickel-cobalt alloy) can be placed on the sealing body 160 side of the side wall 152 of the recessed container 150 (the upper side in the figure), so that the sealing body side of the side wall is made of metal, and the recessed container and the sealing body can be sealed by welding them together.

[0139] The shape of the exterior body in a plan view may be circular or polygonal such as quadrilateral (square or rectangle). In the case of a polygonal shape, the corners may be curved.

[0140] (Elastic conductive member) The elastic conductive member 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, examples include an elastic conductive member having a supported portion 211 shaped according to the support portion 153 of the recessed container 150 and a flat portion 212 with a spring portion (spring piece) 213, as shown in Figures 1 and 3; an elastic conductive member having a cross-sectional shape that has a locking portion shaped according to the support portion of the recessed container and a recess that presses the electrode stack; etc.

[0141] The elastic conductive member can be formed from a plate made of nickel, iron, copper, chromium, cobalt, titanium, aluminum, or an alloy thereof. Of the metals exemplified above, stainless steel plate and nickel-plated stainless steel plate are preferred as the metal constituting the elastic conductive member, and in order to facilitate the function of the leaf spring, stainless steel for springs such as SUS301-CSP, SUS304-CSP, SUS316-CSP, SUS420J2-CSP, SUS631-CSP, and SUS632J1-CSP are more preferred.

[0142] The thickness of the metal plate constituting the elastic conductive member is preferably 0.05 mm or more, more preferably 0.07 mm or more, and even more preferably 0.1 mm or more, in order to ensure a certain level of pressing force against the electrode laminate. On the other hand, in order to prevent the elastic conductive member from becoming too thick, which would increase the storage volume inside the battery container, and to make the elastic conductive member easily deformable so that it can be easily engaged with the side wall portion of the concave container, the thickness of the metal plate constituting the elastic conductive member is preferably 0.5 mm or less, more preferably 0.4 mm or less, and even more preferably 0.3 mm or less.

[0143] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples.

[0144] (Example 1) Lithium titanate (Li) having an average particle size of 2 μm ４ Ti ５ O １２ , negative electrode active material) and a sulfide-based solid electrolyte (Li ６ P.S. ５ Cl) and graphene (conductive additive) were mixed in a mass ratio of 50:41:9 to prepare a negative electrode mixture.

[0145] In addition, LiNbO ３ LiCoO having an average particle size of 5 μm on which a coating layer of ２ (positive electrode active material) and a sulfide-based solid electrolyte (Li ６ P.S. ５ Cl) and graphene were mixed in a mass ratio of 65:30.7:4.3 to prepare a positive electrode mixture.

[0146] Next, a sulfide-based solid electrolyte (Li ６ P.S. ５ A powder of HCl) 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 a 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 a negative electrode on the provisionally molded layer of the solid electrolyte layer.

[0147] Next, a foamed metal substrate (Celmet (registered trademark) made by Sumitomo Electric Industries, Ltd., made of a Ni-Cr alloy with Ni and Cr contents of 95% by mass and 5% by mass, respectively) cut to a diameter of 7.25 mm (thickness: 1.1 mm, porosity: 98%, basis weight: 347 g / m) was applied onto the provisionally formed layer of the negative electrode formed on the provisionally formed layer of the solid electrolyte layer. ２ ) was placed as a current collector, and pressure molding was performed at a surface pressure of 300 MPa to form an integrated product of the solid electrolyte layer and the negative electrode.

[0148] 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.

[0149] Next, a cut foamed metal substrate made of a Ni—Cr alloy having the same composition as that used for the negative electrode was placed as a current collector on the provisionally molded layer of the positive electrode formed on the solid electrolyte layer, and pressure molding was performed at a surface pressure of 1400 MPa to obtain an electrode laminate.

[0150] In the obtained electrode laminate, the thickness of the negative electrode mixture layer of the negative electrode, the thickness of the metal substrate, and the thickness of the portion of the metal substrate embedded in the negative electrode mixture layer were 1400 μm, 60 μm (5% of the thickness of the metal substrate before use in the negative electrode), and 60 μm (100% of the total thickness of the metal substrate), respectively. In addition, the area ratio of the portion of the negative electrode mixture exposed on the surface of the negative electrode was 7%.

[0151] In the obtained electrode laminate, the thickness of the positive electrode mixture layer of the positive electrode, the thickness of the metal substrate, and the thickness of the portion of the metal substrate embedded in the positive electrode mixture layer were 800 μm, 60 μm (5% of the thickness of the metal substrate before use in the positive electrode), and 60 μm (100% of the total thickness of the metal substrate), respectively. The area ratio of the portion of the positive electrode mixture exposed on the surface of the positive electrode was 7%.

[0152] A foamed metal substrate made of a Ni-Cr alloy (i.e., Ni and Cr contents of 95% and 5% by mass, respectively) with a diameter of 7.25 mm was cut and placed on the inner bottom surface of a concave container (2.5 mm deep) with a structure similar to that shown in Figures 1 and 2, with a seal ring made of an iron-nickel-cobalt alloy disposed on the upper sidewall. The metal substrate served as a conductive connecting member and contacted the conductive path of the positive electrode. The electrode stack was then placed on top of the foamed metal substrate with the positive electrode facing downward. Furthermore, an elastic conductive member made of a stainless steel plate (0.2 mm thick) with a shape similar to that shown in Figures 1 and 3 was placed on top of the negative electrode of the electrode stack, with its supported portion engaging with the support portion of the concave container. The spring piece of the elastic conductive member was then bent toward the negative electrode of the electrode laminate, with its tip facing the flat portion. The spring piece was brought into contact with the negative electrode of the electrode laminate at a point closer to the boundary with the flat portion than the tip, pressing the electrode laminate 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 an all-solid-state secondary battery. In the resulting all-solid-state secondary battery, as described above, the elastic conductive member pressed the electrode laminate toward the inner bottom surface of the recessed container, thereby pressing the electrode laminate against the conductive connecting member made of a foamed metal substrate. Furthermore, the thickness of the conductive connecting member (foamed metal substrate) in the assembled all-solid-state secondary battery was 200 μm.

[0153] (Comparative Example 1) The conductive connecting member to be placed on the inner bottom surface of the concave container was a foamed metal substrate (basis weight: 330 g / m) made of pure Ni containing no Cr. ２ An all-solid-state secondary battery was fabricated in the same manner as in Example 1, except that the above-mentioned material was changed to the above-mentioned material.

[0154] (Comparative Example 2) An all-solid-state secondary battery was fabricated in the same manner as in Comparative Example 1, except that the foam metal substrates used as the current collectors of the positive and negative electrodes were changed to substrates made of pure Ni, the same as those used as the conductive connecting members in Comparative Example 1.

[0155] The all-solid-state secondary batteries of the Examples and Comparative Examples were charged at a constant current of 4 mA until the voltage reached 2.6 V, then charged at a constant voltage of 2.6 V until the current reached 0.05 mA, and then discharged at a constant current of 0.4 mA until the voltage reached 1.0 V.

[0156] Next, each battery was stored in a thermostatic chamber at 115°C for 28 days, taken out and cooled to room temperature, and then subjected to constant current charging, constant voltage charging and constant current discharging under the same conditions as above to measure the discharge capacity after storage.

[0157] Furthermore, the battery whose resistance was measured after storage was disassembled, and the presence or absence of corrosion of the porous metal substrate disposed between the positive electrode of the electrode laminate and the exterior body, and the current collector was confirmed by SEM.

[0158] The results are shown in Table 1.

[0159]

[0160] In the battery of Example 1, the conductive connecting member and the current collector were each made of a Ni-Cr alloy, which suppressed the increase in resistance due to corrosion of the substrate, and enabled a larger discharge capacity after storage than the battery of Comparative Example 1, in which the conductive connecting member was made of Ni, and the battery of Comparative Example 2, in which both the conductive connecting member and the current collector were made of Ni.

[0161] In addition to the above, when the substrate serving as the conductive connecting member was changed to an alloy having a composition of Ni 85% by mass - Cr 15% by mass, Ni 75% by mass - Cr 25% by mass, or Ni 65% by mass - Cr 35% by mass, all-solid-state secondary batteries were produced in the same manner as above and stored at 115°C for 28 days, and it was confirmed that no corrosion of the conductive connecting member occurred.

[0162] Furthermore, the resistance values ​​of the substrates (resistance values ​​of the substrates alone before assembling the battery) for each of the alloy compositions are shown in Table 2. From the viewpoint of reducing the internal resistance of the battery, it is clear that the Cr content is preferably 30% by mass or less, more preferably 20% by mass or less, and particularly preferably 10% by mass or less.

[0163]

[0164] The present invention can be implemented in other forms without departing from the spirit of the present invention. The embodiments disclosed in this application are merely examples, and the present invention is not limited to these embodiments. The scope of the present invention shall be interpreted in accordance with the appended claims rather than the description in the above specification, and all modifications within the scope of the claims are included in the scope of the claims.

[0165] The all-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.

[0166] REFERENCE SIGNS LIST 100 All-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 surface 152 Side wall 153 Support portion 160 Sealing body 170 Connection terminal portion 171 Conductive path 180 Connection terminal portion 181 Conductive path 190 Porous metal substrate 200 Seal ring 210 Elastic conductive member 211 Supported portion 212 Planar portion 213 Spring portion (spring piece) 213a Boundary 213b Tip portion

Claims

1. An all-solid-state battery comprising an electrode laminate having a positive electrode, a negative electrode, and a solid electrolyte layer, and an exterior body enclosing the electrode laminate, wherein the exterior body has a conductive path leading from the inside to the outside, and a porous metal substrate is provided between the positive electrode and / or the negative electrode and the conductive path of the exterior body, at least one of the positive electrode, the negative electrode, and the solid electrolyte layer contains a sulfide-based solid electrolyte, the porous metal substrate is made of an alloy containing Ni and Cr, the Ni content of the alloy is 60 mass% or more, and the Cr content of the alloy is 0.1 mass% or more and 40 mass% or less.

2. The all-solid-state battery according to claim 1, wherein the Ni content in the alloy is 70 mass % or more.

3. The all-solid-state battery according to claim 1, wherein the Cr content in the alloy is 30 mass % or less.

4. The all-solid-state battery according to claim 1, wherein the sulfide-based solid electrolyte contains an argyrodite-type solid electrolyte.

5. The weight of the porous metal substrate is 600 g / m ２ The all-solid-state battery according to claim 1 , wherein:

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