Electrode laminate, manufacturing method therefor, and electrochemical element

Abstract

Provided are: an electrochemical element having excellent reliability and productivity; an electrode laminate for constituting said electrochemical element; and a manufacturing method therefor.　This electrode laminate comprises a first electrode, a second electrode, and a solid electrolyte layer interposed therebetween, wherein: at least one electrode among the first electrode and the second electrode has an electrode mixture layer that is obtained by pressure-molding a powdery electrode mixture and has a circular outer peripheral edge having a diameter D in a plan view, and a sheet-like porous metal substrate; the porous metal substrate is integrated with the electrode mixture layer by embedding, in a surface layer part of the electrode mixture layer, at least one portion including an end part on the side of the electrode mixture layer; the porous metal substrate has an approximately polygonal shape in a plan view, and all corner parts of the approximately polygonal shape are positioned between the outer peripheral edge of the electrode mixture layer and a concentric circle of the outer peripheral edge of the electrode mixture layer, which has a diameter of 0.7 D. This electrochemical element is obtained by sealing said electrode laminate within an exterior body.

Description

Electrode stack, method for manufacturing the same, and electrochemical element

[0001] The present invention relates to an electrochemical element with excellent reliability and productivity, an electrode laminate for constituting the electrochemical element, and a method for manufacturing the same.

[0002] While non-aqueous electrolyte batteries, such as lithium-ion batteries using organic electrolytes, are widely used, in recent years, with the expansion of their application fields, there has been a demand for higher capacity and use in high-temperature environments, and consequently, there has been a growing need for improved safety, for example.

[0003] For these reasons, solid electrolyte batteries, such as all-solid-state batteries, which can ensure excellent heat resistance by using molded solid electrolytes instead of organic electrolytes that use flammable organic solvents, are attracting increasing attention.

[0004] Currently, various studies are being conducted on solid electrolyte batteries. For example, Patent Document 1 proposes a technique to reduce internal resistance by constructing an electrochemical element by housing an electrode stack, which comprises a first electrode, a second electrode, and an isolation layer such as a solid electrolyte layer interposed between them, in an outer casing having a conductive path from the inside to the outside, wherein at least one of the first and second electrodes in the electrode stack has an electrode mixture layer and a sheet-like porous metal substrate, and the porous metal substrate of the electrode is embedded in the surface layer of the electrode mixture layer in at least a part of it, including the end on the electrode mixture layer side, thereby integrating it with the electrode mixture layer, the other end of the porous metal substrate is exposed on the surface of the electrode, and the porous metal substrate on the surface of the electrode stack is brought into contact with the conductive path of the outer casing, thereby making the electrode and the conductive path electrically connected.

[0005] International Publication No. 2023 / 238926

[0006] Incidentally, in an electrode laminate using a porous metal substrate as a current collector, which is embedded in the surface layer of the electrode mixture layer and integrated with the electrode mixture layer, as described in Patent Document 1, cracks are likely to occur in the isolation layer and electrode mixture layer during manufacturing, which can lead to a decrease in the reliability and productivity of the electrode laminate and the electrochemical element using it. Furthermore, during the manufacturing of the electrode laminate, metal powder may be generated from the porous metal substrate and adhere to the sides of the electrode laminate, which may cause a short circuit in the electrochemical element. Therefore, there is still room for improvement in the technology described in Patent Document 1 in these respects.

[0007] The present invention has been made in view of the above circumstances, and its object is to provide an electrochemical element with excellent reliability and productivity, an electrode laminate for constituting the electrochemical element, and a method for manufacturing the same.

[0008] The electrode laminate of the present invention comprises a first electrode, a second electrode, and a solid electrolyte layer interposed between them, wherein at least one of the first electrode and the second electrode has an electrode mixture layer formed by pressure molding of a powdery electrode mixture, the outer edge of which is circular in diameter D in plan view, and a sheet-like porous metal substrate, wherein at least a portion of the porous metal substrate, including the end on the electrode mixture layer side, is embedded in the surface layer of the electrode mixture layer and integrated with the electrode mixture layer, the other end of the porous metal substrate is exposed on the surface of the electrode, the porous metal substrate is substantially polygonal in plan view, and all corners of the substantially polygon are located between the outer edge of the electrode mixture layer and the concentric circles of the outer edge of the electrode mixture layer, which have a diameter of 0.7D.

[0009] The electrode laminate of the present invention comprises the following steps: a first step of forming a provisional molded body of the electrode having an electrode mixture layer and a sheet-like porous metal substrate by pouring the electrode mixture into a mold and applying pressure; a second step of placing a sheet-like porous metal substrate, which has a substantially polygonal shape in plan view, on the provisional molded body of the electrode mixture formed in the first step, such that in plan view, the outer edge of the porous metal substrate is inward from the outer edge of the provisional molded body of the electrode mixture; and a third step of pressing and compressing the porous metal substrate toward the provisional molded body of the electrode mixture so that at least a portion of the porous metal substrate, including the end on the electrode mixture side, is embedded in the electrode mixture, thereby forming an electrode mixture layer integrated with the porous metal substrate, wherein the third step is performed for the electrode mixture for the first electrode. The present invention can be manufactured by a manufacturing method characterized by the following: carrying out the manufacturing by stacking a provisional molded body, a provisional molded body of the electrode mixture for the first electrode on which the porous metal substrate is placed, or the first electrode, the solid electrolyte layer or a provisional molded body of a solid electrolyte obtained by pressure molding a solid electrolyte, and a provisional molded body of the electrode mixture for the second electrode on which the porous metal substrate is placed; or carrying out the manufacturing by stacking a provisional molded body of the electrode mixture for the first electrode on which the porous metal substrate is placed, the solid electrolyte layer or a provisional molded body of a solid electrolyte obtained by pressure molding a solid electrolyte, a provisional molded body of the electrode mixture for the second electrode on which the porous metal substrate is placed, or the second electrode.

[0010] Furthermore, the electrochemical element of the present invention comprises an outer casing and an electrode laminate of the present invention sealed inside the outer casing, wherein the outer casing has a conductive path that leads from the inside to the outside, and the porous metal substrate on the surface of the electrodes of the electrode laminate is brought into contact with the conductive path, thereby creating electrical conductivity between the electrodes and the conductive path.

[0011] According to the present invention, it is possible to provide an electrochemical element with excellent reliability and productivity, an electrode laminate for constituting the electrochemical element, and a method for manufacturing the same.

[0012] This is a scanning electron microscope image illustrating an example of the surface state of an electrode having an electrode mixture layer formed by pressure molding of a powdered electrode mixture and a sheet-like porous metal substrate. This is a drawing illustrating the arrangement of the electrode mixture layer and the sheet-like porous metal substrate in the electrode laminate of the present invention. This is a drawing showing an example of the plan view shape of the sheet-like porous metal substrate. This is a schematic cross-sectional view showing an example of an electrochemical element of the present invention.

[0013] The electrode laminate of the present invention comprises a first electrode, a second electrode, and a solid electrolyte layer interposed between them, wherein at least one of the first electrode and the second electrode comprises an electrode mixture layer and a sheet-like porous metal substrate (hereinafter sometimes simply referred to as "porous metal substrate"), wherein at least a portion of the porous metal substrate, including the end on the electrode mixture layer side, is embedded in the surface layer of the electrode mixture layer and integrated with the electrode mixture layer, and the other end of the porous metal substrate is exposed on the surface of the electrode.

[0014] In other words, in the electrode laminate of the present invention, at least one of the two electrodes has an electrode mixture layer and a sheet-like porous metal substrate, and a certain range in the thickness direction from the end (end face) on the electrode mixture layer side of the porous metal substrate, which functions as a current collector, is embedded in the surface layer of the electrode mixture layer. Therefore, the electrode mixture constituting the electrode mixture layer is held in at least a part of the pores of the porous metal substrate, so that the porous metal substrate and the electrode mixture layer are integrated, and as a result the conductivity between the electrode mixture layer and the current collector is very good.

[0015] Incidentally, when manufacturing electrodes using a powdered electrode mixture, for example, the electrode mixture can be placed in a mold and pressurized at a relatively low pressure to form a preliminary molded body (preliminary molding), and then the pressure can be increased further (final molding) to manufacture the electrodes.

[0016] Furthermore, in the case of an electrode having an electrode mixture layer formed by pressure molding of a powdered electrode mixture and a sheet-like porous metal substrate, wherein at least a portion of the porous metal substrate, including the end on the electrode mixture layer side, is embedded in the surface layer of the electrode mixture layer and integrated with the electrode mixture layer, the electrode can be manufactured by first pouring the electrode mixture into a mold and pressurizing it to form a temporary molded body, then placing the sheet-like porous metal substrate on this temporary molded body, and pressing and compressing the porous metal substrate toward the temporary molded body of the electrode mixture.

[0017] Furthermore, when manufacturing an electrode laminate having an electrode with such a structure in at least one of the first electrode and the second electrode, the formation of the electrode mixture layer integrated with the porous metal substrate in the electrode can be carried out by (1) stacking a provisional molded body of the electrode mixture for the first electrode or the first electrode, a solid electrolyte layer or a provisional molded body of a solid electrolyte formed by pressure molding of a solid electrolyte, and a provisional molded body of the electrode mixture for the second electrode on which the porous metal substrate is placed, or (2) stacking a provisional molded body of the electrode mixture for the first electrode on which the porous metal substrate is placed, a solid electrolyte layer or a provisional molded body of a solid electrolyte formed by pressure molding of a solid electrolyte, and a provisional molded body of the electrode mixture for the second electrode or the second electrode. By adopting such a manufacturing method, an electrode laminate can be formed at the same time as forming an electrode mixture layer integrated with the porous metal substrate.

[0018] However, our investigations have revealed that when an electrode composite layer is formed by integrating it with a porous metal substrate using the method described above, and an electrode laminate is formed at the same time, cracks tend to occur in the electrode composite layer and the solid electrolyte layer at or near the outer edges, in a direction parallel to the plane of the electrode and solid electrolyte layers.

[0019] The reason is not entirely clear, but it is speculated that it is due to the following mechanism. When a porous metal substrate is pressed in a mold with an electrode mixture on top, the porous metal substrate is compressed and its thickness decreases, and it also tries to expand in a direction perpendicular to the direction of pressure (parallel to the plane direction of the porous metal substrate). However, as it is pressed while creating thickness variations in the pre-formed electrode mixture layer and solid electrolyte layer, stress concentrates in the areas with greater thickness. Furthermore, when the outer edge of the porous metal substrate comes into contact with the inner wall of the mold, it cannot expand any further, so the pressure on the electrode mixture layer and solid electrolyte layer becomes even greater at that point. Therefore, when multiple layers are pressed together to form the electrode mixture layer and the electrode laminate simultaneously, the stress at the outer edges of the electrode mixture layer and solid electrolyte layer and in their vicinity tends to become very large. If the aforementioned stress remains at the end of the pressing process, when the electrode laminate is removed from the mold, it acts in a direction that causes the electrode mixture layer and solid electrolyte layer to expand, which is thought to cause cracks in the weaker layers (electrode mixture layer and solid electrolyte layer). Furthermore, when an electrode laminate is formed by simultaneously pressurizing multiple layers, the expansion rate after removal from the mold differs for each layer, which further exacerbates the occurrence of the aforementioned cracks. The inventors have confirmed that the aforementioned cracks in the electrode laminate hardly occur when a porous metal substrate for the electrodes is not used.

[0020] Furthermore, when an electrode composite layer is formed by integrating it with a porous metal substrate using the method described above, and an electrode laminate is formed at the same time, the outer edge of the porous metal substrate, which expands in a direction perpendicular to the direction of pressure due to the pressure, may come into contact with the inner wall of the mold, causing metal powder to be generated from the outer edge or its vicinity. If this metal powder adheres to the electrode laminate when it is removed from the mold after pressure is applied, it may cause an internal short circuit in the electrochemical element using this electrode laminate.

[0021] Therefore, the inventors conducted further studies and found that when the outer edge of the electrode mixture layer is circular in diameter D in plan view, a sheet-like porous metal substrate that is substantially polygonal in plan view is used, and after molding, all corners of the substantially polygonal porous metal substrate after pressurization are located between the outer edge of the electrode mixture layer and the concentric circles of the outer edge of the electrode mixture layer with a diameter of 0.7D, thereby suppressing the occurrence of cracks in the electrode laminate and the generation of metal powder from the porous metal substrate. Thus, in the present invention, by using this electrode laminate, it is possible to improve the reliability and productivity of electrochemical elements. The details of the present invention will be described below.

[0022] <Electrode Stack> The electrode stack comprises a first electrode, a second electrode, and a solid electrolyte layer interposed between them.

[0023] When an electrochemical element using an electrode stack is a battery or a lithium-ion capacitor, one of the first electrode and the second electrode is the positive electrode and the other is the negative electrode. Furthermore, when an electrochemical element using an electrode stack is an electric double-layer capacitor, electrodes with the same configuration can be used for both the first and second electrodes.

[0024] Furthermore, as described above, at least one of the first electrode and the second electrode has an electrode mixture layer and a sheet-like porous metal substrate, and at least a portion of the porous metal substrate, including the end on the electrode mixture layer side, is embedded in the surface layer of the electrode mixture layer and integrated with the electrode mixture layer, while the other end of the porous metal substrate is exposed on the surface of the electrode.

[0025] In an electrode stack used in a battery, if the electrode having the above configuration is the positive electrode, the electrode mixture layer is composed of a positive electrode mixture containing a positive electrode active material and the like.

[0026] When the electrode having the above structure is the positive electrode of a primary battery, the same positive electrode active materials as those used in known non-aqueous electrolyte primary batteries, alkaline batteries, manganese batteries, etc. can be used. Specifically, for example, manganese dioxide, lithium-containing manganese oxides [e.g., LiMn ３ O ６ and composite oxides having the same crystal structure as manganese dioxide (such as β-type, γ-type, or a structure in which β-type and γ-type are mixed), with a Li content of 3.5% by mass or less, preferably 2% by mass or less, more preferably 1.5% by mass or less, and particularly preferably 1% by mass or less, etc.], Li ａ Ti ５／３ O ４ (4 / 3 ≦ a < 7 / 3) and other lithium-containing composite oxides; vanadium oxides; niobium oxides; titanium oxides; sulfides such as iron disulfide; graphite fluoride; Ag ２ S and other silver sulfides; nickel oxides such as NiO ２ etc.: and the like can be mentioned.

[0027] Further, when the electrode having the above structure is the positive electrode of a secondary battery, the same positive electrode active materials as those used in known non-aqueous electrolyte secondary batteries, alkaline secondary batteries, etc. can be used. Specifically, Li １－ｘ M ｒ Mn ２－ｒ O ４ (where M is at least one element selected from the group consisting of Li, Na, K, B, Mg, Ca, Sr, Ba, Ti, V, Cr, Zr, Fe, Co, Ni, Cu, Zn, Al, Sn, Sb, In, Nb, Ta, Mo, W, Y, Ru, and Rh, 0 ≦ x ≦ 1, 0 ≦ r ≦ 1) spinel-type lithium manganese composite oxides represented by, Li ｒ Mn （１－ｓ－ｔ） Ni ｓ M ｔ O （２－ｕ） F ｖ (where M is at least one element selected from the group consisting of Co, Mg, Al, B, Ti, V, Cr, Fe, Cu, Zn, Zr, Mo, Sn, Ca, Sr, and W, 0 ≦ r ≦ 1.2, 0 < s < 0.5, 0 ≦ t ≦ 0.5, u + v < 1, -0.1 ≦ u ≦ 0.2, 0 ≦ v ≦ 0.1) layered compounds represented by, Li１－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, 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, Mn, Fe, Co, Cu, Zn, Ga, Ge, Nb, Mo, Sn, Sb, and Ba, and 0 ≤ x ≤ 1, 0 ≤ r ≤ 0.5) Lithium nickel composite oxide, Li １＋ｓ－ｘ M １－ｒ N ｒ PO 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) Olivine-type composite oxide, Li ２－ｘ M １－ｒ N ｒ P ２ O ７ Examples of pyrophosphate compounds, nickel hydroxide, silver oxide, etc., represented by (where M is at least one element selected from the group consisting of Fe, Mn, and Co, and N is at least one element selected from the group consisting of Al, Mg, Ti, Zr, Ni, Cu, Zn, Ga, Ge, Nb, Mo, Sn, Sb, V, and Ba, with 0 ≤ x ≤ 2 and 0 ≤ r ≤ 0.5), may be used individually or in combination of two or more.

[0028] When the electrochemical element is an all-solid-state secondary battery, the average particle size of the positive electrode active material is preferably 1 μm or more, more preferably 2 μm or more, preferably 10 μm or less, and more preferably 8 μm or less. The positive electrode active material may be primary particles or secondary particles formed by aggregation of primary particles. Using a positive electrode active material with an average particle size within the above range allows for a larger interface with the solid electrolyte contained in the positive electrode, thereby improving the output characteristics of the battery.

[0029] The average particle diameter of the various particles referred to herein (such as positive electrode active material and solid electrolyte) is the 50% diameter value in the volume-based integrated fraction when determining the integrated volume from the smallest particles using a particle size distribution analyzer (such as the Microtrac particle size distribution analyzer "HRA9320" manufactured by Nikkiso Co., Ltd.). ５０ This means...

[0030] In the case of an all-solid-state secondary battery, it is preferable that the positive electrode active material has a reaction-inhibiting layer on its surface to suppress the reaction with the solid electrolyte contained in the positive electrode.

[0031] If the positive electrode active material and the solid electrolyte come into direct contact within the electrode mixture layer (positive electrode mixture layer), the solid electrolyte may oxidize and form a resistive layer, potentially reducing the ionic conductivity within the electrode mixture layer. By providing a reaction-inhibiting layer on the surface of the positive electrode active material to suppress the reaction with the solid electrolyte, direct contact between the positive electrode active material and the solid electrolyte can be prevented, thereby suppressing the reduction in ionic conductivity within the electrode mixture layer due to oxidation of the solid electrolyte.

[0032] The reaction suppression layer should be composed of a material that has ionic conductivity and can suppress the reaction between the positive electrode active material and the solid electrolyte. Examples of materials that can constitute 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 PO ４ Li ３ BO ３ Li ４ SiO ４ Li ４ GeO４ LiTio ３ LiZrO ３ Li ２ WO ４ These are some examples. The reaction suppression layer may contain only one of these oxides, or it may contain two or more, and furthermore, multiple of these oxides may form a composite compound. Among these oxides, it is preferable to use an Nb-containing oxide, such as LiNbO ３ It is more preferable to use [this].

[0033] The reaction-inhibiting layer is preferably present on the surface in an amount of 0.1 to 2.0 parts by mass per 100 parts by mass of the positive electrode active material. Within this range, the reaction between the positive electrode active material and the solid electrolyte can be effectively suppressed.

[0034] Methods for forming a reaction-inhibiting layer on the surface of the positive electrode active material include the sol-gel method, mechanofusion method, CVD method, PVD method, and ALD method.

[0035] From the viewpoint of increasing the energy density of the electrochemical element, the content of the positive electrode active material in the positive electrode mixture is preferably 60 to 85% by mass.

[0036] The positive electrode mixture can contain conductive additives. Specific examples include carbon materials such as graphite (natural graphite, artificial graphite), graphene, carbon black, carbon nanofibers, and carbon nanotubes. For example, Ag can be used as the active material. ２ When sulfur (S) is used, conductive Ag is generated during the discharge reaction, so a conductive additive does not need to be included. When a conductive additive is included in the positive electrode mixture, its content 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, based on the content of 100 parts by mass of the positive electrode active material.

[0037] Furthermore, a binder can be included in the positive electrode mixture. Specific examples include fluororesins such as polyvinylidene fluoride (PVDF). However, if good moldability can be ensured in forming the electrode mixture layer (positive electrode mixture layer) without using a binder, for example, when the positive electrode mixture contains a sulfide-based solid electrolyte (details will be discussed later), then the positive electrode mixture does not need to contain a binder.

[0038] In the positive electrode mixture, if a binder is required, its content is preferably 15% by mass or less, and more preferably 0.5% by mass or more. On the other hand, in the positive electrode mixture, if moldability can be obtained without the need for a binder, its content is preferably 0.5% by mass or less, more preferably 0.3% by mass or less, and even more preferably 0% by mass (i.e., no binder is included).

[0039] When the electrochemical element is an all-solid-state battery (all-solid-state primary battery, all-solid-state secondary battery), it is preferable to include a solid electrolyte in the positive electrode mixture.

[0040] The solid electrolyte to be included in the positive electrode mixture is not particularly limited as long as it has lithium ion conductivity, and for example, sulfide-based solid electrolytes, hydride-based solid electrolytes, halide-based solid electrolytes, oxide-based solid electrolytes, etc., can be used.

[0041] As a sulfide-based solid electrolyte, 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 Examples include glass particles, as well as thio-LiSICON type [Li １０ GeP ２ S １２ Li ９．５４ Si １．７４ P １．４４ S１１．７ Cl ０．３ such as Li12−12a−b + c + 6d−eM １ ３＋ａ－ｂ－ｃ－ｄ M ２ ｂ M ３ ｃ M ４ ｄ M ５ １２－ｅ X ｅ (where 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, X is F, Cl, Br or I, 0 ≤ a < 3, 0 ≤ b + c + d ≤ 3, 0 ≤ e ≤ 3), or those of the aljilotite type [Li ６ PS ５ Cl etc., Li ７－ｋ PS ６－ｋ X ｋ (where X represents one or more halogen elements, 0.2 < k < 2.0), those represented by Li ７－ｆ＋ｇ PS ６－ｆ Cl ｆ＋ｇ (where 0.05 ≤ g ≤ 0.9, −3.0f + 1.8 ≤ g ≤ −3.0f + 5.7), those represented by Li ７－ｈ PS ６－ｈ Cl ｉ Br ｊ (where h = i + j, 0 < h ≤ 1.8, 0.1 ≤ i / j ≤ 10.0), etc.] can also be used.

[0042] As the hydride-based solid electrolyte, for example, LiBH ４ , LiBH ４ and a solid solution with the following alkali metal compound (for example, LiBH ４Examples include those with a molar ratio of 1:1 to 20:1 between the solid solution and the alkali metal compound. Examples of alkali metal compounds in the solid solution include 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.

[0043] Examples of halide-based solid electrolytes include monoclinic LiAlCl ４ , defective spinel type or layered structure LiInBr ４ Monoclinic Li ６－３ｍ Y ｍ X ６ (However, this includes cases where 0 < m < 2 and X = Cl or Br), and other publicly known examples can also be used, such as those described in International Publication No. 2020 / 070958 and International Publication No. 2020 / 070955.

[0044] Examples of oxide-based solid electrolytes include Li ２ O-Al ２ O ３ -SiO ２ -P ２ O ５ -TiO ２ Glass ceramics, Li ２ O-Al ２ O ３ -SiO ２ -P ２ O ５ -GeO ２ Glass ceramics, garnet-type Li ７ La ３ Zr ２ O １２ , NASICON type Li １＋Ｏ Al １＋Ｏ Ti ２－Ｏ (PO ４ ) ３ Li １＋ｐ Al １＋ｐ Ge ２－ｐ (PO ４ ) ３ Perovskite-type Li ３ｑ La２／３－ｑ TiO ３ These are some examples.

[0045] 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 sulfide-based solid electrolytes, which have high lithium ion conductivity and high chemical stability, are even more preferred.

[0046] The average particle size of the solid electrolyte is preferably 0.1 μm or larger, and more preferably 0.2 μm or larger, from the viewpoint of reducing grain boundary resistance. On the other hand, from the viewpoint of forming a sufficient contact interface between the active material and the solid electrolyte, it is preferably 10 μm or smaller, and more preferably 5 μm or smaller.

[0047] From the viewpoint of further enhancing ionic conductivity within the positive electrode and improving the output characteristics of the electrochemical element, the solid electrolyte content in the positive electrode mixture is preferably 10 parts by mass or more, and more preferably 15 parts by mass or more, when the positive electrode active material content is 100 parts by mass. However, if the amount of solid electrolyte in the positive electrode mixture is too high, the amount of other components will decrease, and the effects of those components may be reduced. Therefore, the solid electrolyte content in the positive electrode mixture is preferably 65 parts by mass or less, and more preferably 60 parts by mass or less, when the positive electrode active material content is 100 parts by mass.

[0048] In an electrode stack used in a battery, if the electrode having the above configuration is the negative electrode, the electrode mixture layer is composed of a negative electrode mixture containing a negative electrode active material and the like.

[0049] Examples of negative electrode active materials include carbon materials such as graphite, lithium titanium oxide (such as lithium titanate), elements such as Si and Sn, elements in elemental form or compound (such as oxides), and their alloys. Lithium metal and lithium alloys (such as lithium-aluminum alloy and lithium-indium alloy) can also be used as negative electrode active materials.

[0050] From the viewpoint of increasing the energy density of the battery, the content of the negative electrode active material in the negative electrode mixture is preferably 40 to 80% by mass.

[0051] The negative electrode mixture may contain a conductive additive. Specific examples include the same conductive additives exemplified earlier as those that can be included in the positive electrode mixture. The content of the conductive additive in the negative electrode mixture is preferably 10 to 30 parts by mass, based on 100 parts by mass of the negative electrode active material.

[0052] Furthermore, a binder can be included in the negative electrode mixture. Specific examples include the same binders mentioned earlier that can be included in the positive electrode mixture. However, if good moldability can be ensured in forming the electrode mixture layer (negative electrode mixture layer) without using a binder, such as when the negative electrode mixture contains a sulfide-based solid electrolyte (as described later), then the negative electrode mixture does not need to contain a binder.

[0053] In the negative electrode mixture, if a binder is required, its content is preferably 15% by mass or less, and more preferably 0.5% by mass or more. On the other hand, in the negative electrode mixture, if moldability can be obtained without the need for a binder, its content is preferably 0.5% by mass or less, more preferably 0.3% by mass or less, and even more preferably 0% by mass (i.e., no binder is included).

[0054] When the electrochemical element is an all-solid-state battery, it is preferable to include a solid electrolyte in the negative electrode mixture. Specific examples include the same solid electrolytes exemplified earlier that can be included in the positive electrode mixture. Among the exemplified solid electrolytes, sulfide-based solid electrolytes are preferred because they have high lithium-ion conductivity and also enhance the moldability of the negative electrode mixture; more preferably, sulfide-based solid electrolytes having an argyrodite crystal structure are used.

[0055] For the same reasons as in the case of the positive electrode mixture, the average particle size of the solid electrolyte is preferably 0.1 μm or more, more preferably 0.2 μm or more, more preferably 10 μm or less, and more preferably 5 μm or less.

[0056] From the viewpoint of further enhancing ionic conductivity within the negative electrode and improving the output characteristics of the electrochemical element, the solid electrolyte content in the negative electrode mixture is preferably 30 parts by mass or more, and more preferably 35 parts by mass or more, when the negative electrode active material content is 100 parts by mass. However, if the amount of solid electrolyte in the negative electrode mixture is too high, the amount of other components will decrease, and the effects of those components may be reduced. Therefore, the solid electrolyte content in the negative electrode mixture is preferably 130 parts by mass or less, and more preferably 110 parts by mass or less, when the negative electrode active material content is 100 parts by mass.

[0057] When the electrochemical element using the electrode stack is an electric double-layer capacitor, the electrode mixture layer of the electrode having the above configuration can be formed by an electrode mixture having the same configuration as the positive electrode mixture, except that activated carbon is used as the active material.

[0058] Furthermore, when the electrochemical element using the electrode stack is a lithium-ion capacitor, the electrode composite layer of the electrode having the above configuration can be formed by an electrode composite having the same configuration as the electrode composite for the electrode of an electric double-layer capacitor if the electrode is a positive electrode, and by an electrode composite having the same configuration as the negative electrode composite if the electrode is a negative electrode.

[0059] In the electrode having the above configuration, it is preferable to use a foamed metal porous material as the porous metal substrate. Examples of porous metal substrates include Ni, Al, Ti, W, Mo, Cr, Cu, and alloys containing these elements (such as Ni-Cr alloy, Ni-Sn alloy, Ti-Al alloy), and stainless steel (such as SUS304 and SUS316). A specific example of a foamed metal porous material is "Cellmet®" from Sumitomo Electric Industries, Ltd. Such porous metal substrates are usually compressed and their thickness decreases when electrodes are manufactured together with the electrode mixture, so the thickness before use in the electrode (electrode stack) is greater than the aforementioned thickness (thickness within the electrode). For example, the thickness of the porous metal substrate before compression is preferably 3 mm or less, more preferably 2 mm or less, and particularly preferably 1.5 mm or less. There is no particular lower limit to the thickness of the porous metal substrate before compression, but it is usually 0.1 mm or more. During the manufacturing of the electrode laminate described later, the porous metal substrate is compressed in the thickness direction, resulting in a thickness as shown below.

[0060] The porosity of the porous metal substrate before compression is preferably 80% or more, more preferably 90% or more, and particularly preferably 95% or more, in order to facilitate the filling of the pores in the porous metal substrate with the electrode mixture during the process of pressurizing the porous metal substrate and the electrode mixture, and to allow the porous metal substrate and the electrode mixture layer to easily integrate. On the other hand, in order to increase conductivity by keeping the amount of substrate above a certain level, the porosity is preferably 99.5% or less, more preferably 99% or less, and particularly preferably 98.5% or less.

[0061] If only one of the first electrode and the second electrode in the electrode stack has the above configuration, the other electrode can be, for example, a molded electrode mixture (such as an electrode consisting only of pellets, or an electrode in which the molded electrode mixture (electrode mixture layer) is formed on a current collector (such as a metal foil or other current collector other than a porous metal substrate)), a sheet of lithium, a sheet of lithium alloy, or a sheet of metal that functions as a negative electrode active material (when the electrochemical element is a battery and the electrode is its negative electrode).

[0062] In the electrode with the above configuration, the thickness of the portion of the porous metal substrate embedded in the electrode mixture layer is preferably 10% or more, and more preferably 20% or more, of the total thickness of the porous metal substrate (the total thickness of the porous metal substrate, including the thickness of the portion where the electrode mixture layer coexists; unless otherwise specified, the same applies hereinafter with respect to the thickness of the porous metal substrate), from the viewpoint of more reliably integrating the porous metal substrate and the electrode mixture layer.

[0063] In the electrode configuration described above, in order to reduce the resistance when in contact with the conductive path in the outer casing of the electrochemical element, it is desirable that the end of the porous metal substrate opposite to the electrode mixture layer (hereinafter sometimes referred to as the surface end) is not embedded in the electrode mixture layer, and that the end of the electrode (the electrode surface) is composed solely of the porous metal substrate. That is, when the porous metal substrate is compressed in the thickness direction during the manufacturing of the electrode laminate described later, it is desirable that the voids at the surface end of the porous metal substrate are crushed and eliminated, leaving only the porous metal substrate exposed on the electrode surface. However, some of the voids at the surface end of the porous metal substrate may not be crushed and may remain as voids, or the electrode mixture may be filled into them, and as long as it does not significantly affect the contact resistance with the conductive path, some of the electrode mixture may be exposed on the electrode surface along with the surface end of the porous metal substrate. In other words, as long as the surface end of the porous metal substrate can be exposed on the electrode surface, the entire porous metal substrate (100% of the thickness of the porous metal substrate) may be embedded in the surface layer of the electrode mixture layer. By ensuring that the electrode mixture fills the pores of the porous metal substrate all the way to the electrode surface, the integration of the electrode mixture and the porous metal substrate can be made more reliable.

[0064] Figure 1 shows a scanning electron microscope (SEM) image illustrating the surface condition of an electrode having a porous metal substrate as a current collector. Note that the SEM image in Figure 1 is not a photograph of the surface of an electrode relating to the electrode stack of the present invention, but rather a photograph of an electrode having a surface condition similar to that of the electrode stack of the present invention, and is shown solely for the purpose of illustrating the surface condition of the electrode relating to the electrode stack of the present invention. On the electrode surface shown in Figure 1, the edges of the porous metal substrate 10 are exposed, but a portion of the electrode mixture 11 is also exposed on the electrode surface by entering into voids present at the edges of the porous metal substrate.

[0065] However, as the proportion (area ratio) of the electrode mixture exposed on the electrode surface increases, the contact resistance between the porous metal substrate and the conductive path of the electrochemical element increases. Therefore, it is desirable that the proportion of the exposed electrode mixture area on the electrode surface be 50% or less, more preferably 25% or less, even more preferably 15% or less, and particularly preferably 10% or less, of the area enclosed by the outer edge of the porous metal substrate in a plan view.

[0066] In the electrode with the above configuration, when embedding at least a portion of the porous metal substrate in the surface layer of the electrode mixture layer, from the viewpoint of more reliably integrating the porous metal substrate and the electrode mixture layer, the thickness of the porous metal substrate is preferably 1% or more, more preferably 2% or more, and particularly preferably 3% or more, of the total thickness of the electrode mixture layer (including the thickness of the portion coexisting with the porous metal substrate; hereinafter, "thickness of the electrode mixture layer" means "total thickness of the electrode mixture layer" unless otherwise specified). Furthermore, from the viewpoint of improving the filling properties of the electrode mixture layer in the electrode, the thickness of the porous metal substrate is preferably 30% or less, more preferably 20% or less, and particularly preferably 10% or less, of the thickness of the electrode mixture layer.

[0067] In the electrode configuration described above, the thickness of the porous metal substrate is preferably 10 μm or more, more preferably 20 μm or more, and particularly preferably 30 μm or more, while it is preferably 300 μm or less, more preferably 200 μm or less, and particularly preferably 100 μm or less. Furthermore, the thickness of the electrode mixture layer is preferably 0.2 mm or more, more preferably 0.5 mm or more, and particularly preferably 0.7 mm or more, while it is preferably 2 mm or less, more preferably 1.7 mm or less, and particularly preferably 1.5 mm or less.

[0068] In the electrode with the above configuration, the electrode mixture layer has a circular outer edge in plan view, and when its diameter is D, the porous metal substrate is substantially polygonal in plan view, and all corners of the substantially polygon are located between the outer edge of the electrode mixture layer and a concentric circle of the outer edge of the electrode mixture layer with a diameter of 0.7D (preferably between a concentric circle of the outer edge of the electrode mixture layer with a diameter of 0.8D, and more preferably between a concentric circle of the outer edge of the electrode mixture layer with a diameter of 0.9D).

[0069] Figure 2 shows a diagram illustrating the positional relationship between the electrode mixture layer and the porous metal substrate in a plan view in the electrode laminate of the present invention. As shown in Figure 2, the outer edge 111a of the electrode mixture layer 111 is circular in shape in a plan view. The circles shown by the dashed lines in Figure 2 are concentric circles of the outer edge 111a of the electrode mixture layer 111, and when the diameter of the outer edge 111a is D, the diameter of these concentric circles is 0.7D.

[0070] The porous metal substrate 112 shown in Figure 2 is square in plan view. As shown in Figure 2, all corners (i.e., the four vertices) of the approximately polygonal porous metal substrate 112 are located between the outer edge 111a of the electrode mixture layer 111 and the concentric circles (concentric circles with a diameter of 0.7D).

[0071] As shown in Figure 2, in the electrode laminate of the present invention, the porous metal substrate is arranged such that, in a plan view, all corners of the substantially polygonal porous metal substrate are located between the outer edge of the electrode mixture layer and the concentric circles of the outer edge of the electrode mixture layer, which have a diameter of 0.7D. In this specification, "between the outer edge of the electrode mixture layer and the concentric circles of the outer edge of the electrode mixture layer, which have a diameter of 0.7D", "between the outer edge of the electrode mixture layer and the concentric circles of the outer edge of the electrode mixture layer, which have a diameter of 0.8D", and "between the outer edge of the electrode mixture layer and the concentric circles of the outer edge of the electrode mixture layer, which have a diameter of 0.9D" also include the outer edge and the concentric circles (boundaries formed by concentric circles).

[0072] By reducing the size of the porous metal substrate in plan view used in the manufacture of the electrode laminate, and by ensuring that all corners of the substantially polygonal porous metal substrate are on or inside the outer edge of the electrode mixture layer in the electrode laminate obtained by pressure molding, the occurrence of cracks in the electrode laminate and the generation of metal powder from the porous metal substrate can be suppressed.

[0073] In other words, the aforementioned cracks in the electrode stack are caused by the placement of a porous metal substrate near the outer edge of the electrode mixture layer during the pressure molding process of the electrode stack. Furthermore, metal powder from the porous metal substrate during the pressure molding of the electrode stack is generated when the porous metal substrate deforms and spreads due to the pressure molding, and its outer edge becomes trapped in the side surface of the electrode stack. Therefore, to manufacture the electrode stack, a porous metal substrate with a small planar size should be used so that the porous metal substrate is not placed near the outer edge of the electrode mixture layer during the pressure molding process, and even if the porous metal substrate spreads due to the pressure molding, its outer edge does not become trapped in the side surface of the electrode stack.

[0074] On the other hand, if the area of ​​the porous metal substrate in plan view is made too small, the current collection effect from the electrodes by the porous metal substrate will decrease, which may reduce the effect of reducing the internal resistance of the electrochemical element.

[0075] However, by making the plan view shape of the porous metal substrate approximately polygonal, when manufacturing the electrode laminate by pressure molding, the portion of the porous metal substrate located near the outer edge of the electrode mixture layer can be made as small as possible, thereby suppressing the occurrence of cracks in the electrode laminate. At the same time, the plan view area of ​​the porous metal substrate can be made as large as possible, thereby suppressing a decrease in its current collection function. Furthermore, by ensuring that all corners of the approximately polygonal shape of the porous metal substrate are located in the aforementioned positions in the final electrode laminate, the generation of metal powder from the porous metal substrate during the pressure molding of the electrode laminate can also be suppressed.

[0076] When manufacturing electrochemical elements using multiple electrode stacks, if a large proportion of the electrode stacks have cracks or metal powder from the porous metal substrate adheres to their sides, electrochemical elements with poor characteristics and low reliability may be manufactured, or electrochemical elements with characteristics unsuitable for shipment may be manufactured. However, in the present invention, even when the electrode stack is formed by pressurizing a stacked state in which the first electrode (or its provisional molded form), the solid electrolyte layer (or a provisional molded form of the solid electrolyte), and the second electrode (or its provisional molded form) are stacked, the current collection effect of the porous metal substrate is maintained at a high level, while the occurrence of cracks and the generation of metal powder from the porous metal substrate can be effectively suppressed. Therefore, when a large number of electrochemical elements are manufactured using this method, electrochemical elements with excellent characteristics can be obtained with a high yield. Thus, according to the present invention, it is possible to provide electrochemical elements with excellent reliability and productivity.

[0077] Figure 3 shows an example of the plan view shape of a porous metal substrate. Figure 3(a) shows an example of a pentagonal plan view shape of the porous metal substrate 112, (b) shows an example of a shape in which all five vertices of (a) are curved, the left side of (c) shows an example of a shape in which one of the five sides of (a) (the lower side extending horizontally in the figure) is curved (outward curved), the right side shows a shape in which all five sides of (a) are curved (inward curved), and (d) shows a shape in which the three upper vertices of the five vertices of (a) are curved, and one of the five sides (the lower side extending horizontally in the figure) is curved (outward curved). Also, the porous metal substrate 112 in Figure 3(e) (shown by a solid line) is a Reuleaux pentagon [the dotted line in the figure is the pentagon of (a)]. Thus, the roughly polygonal shape of a porous metal substrate in plan view includes, for example, (a) a polygon, (b) a shape in which at least one vertex of a polygon is curved, (c) a shape in which at least one side of a polygon is curved, and (d) a shape in which at least one vertex of a polygon is curved and at least one side is curved. Furthermore, (c) a shape in which at least one side of a polygon is curved also includes the so-called "Reuleaux polygon," that is, a shape in which each vertex of a polygon is connected to the other vertex by an arc drawn with the diagonal from the center to one end of the opposite side as the radius.

[0078] In this specification, the term "corner" of a substantially polygonal porous metal substrate means, if the substantially polygon has vertices, the portion of the vertex, and if the vertex has a curved shape, the portion of the vertex that has a curved shape. Furthermore, "all corners of the substantially polygonal porous metal substrate are located between the outer edge of the electrode mixture layer and the concentric circles of the outer edge of the electrode mixture layer, which have a diameter of 0.7D" means that all vertices and portions of curved vertices in a porous metal substrate that is substantially polygonal in plan view are located between the outer edge of the electrode mixture layer and the concentric circles of the outer edge of the electrode mixture layer, which have a diameter of 0.7D. In the case where the corners of the porous metal substrate have a curved vertex, it is sufficient that at least a portion of the curved portion is located between the outer edge of the electrode mixture layer and the concentric circles of the outer edge of the electrode mixture layer, which have a diameter of 0.7D. The cases where "all corners of the substantially polygonal shape of the porous metal substrate are located between the outer edge of the electrode mixture layer and the concentric circles of the outer edge of the electrode mixture layer having a diameter of 0.8D" and "all corners of the substantially polygonal shape of the porous metal substrate are located between the outer edge of the electrode mixture layer and the concentric circles of the outer edge of the electrode mixture layer having a diameter of 0.9D" are the same as the case where "all corners of the substantially polygonal shape of the porous metal substrate are located between the outer edge of the electrode mixture layer and the concentric circles of the outer edge of the electrode mixture layer having a diameter of 0.7D," except that "diameter of 0.7D" is read as "diameter of 0.8D" or "diameter of 0.9D."

[0079] Specifically, for example, in the case of a porous metal substrate that is square in plan view, as shown in Figure 2, all four corners, that is, the four vertices, are located between the outer edge of the electrode mixture layer and the concentric circles of the outer edge of the electrode mixture layer, which have a diameter of 0.7D. Also, in the case of a porous metal substrate with the shape shown in Figure 3(d) in plan view, all five corners, that is, the three upper vertices which are curved and the two lower vertices, are located between the outer edge of the electrode mixture layer and the concentric circles of the outer edge of the electrode mixture layer, which have a diameter of 0.7D.

[0080] The plan view shape of the porous metal substrate is approximately polygonal, and it is preferable that the number of vertices of the polygon is between 4 and 8. That is, the plan view shape of the porous metal substrate is preferably approximately quadrilateral, approximately pentagonal, approximately hexagonal, approximately heptagonal, and approximately octagonal. The polygons related to these approximately polygonal shapes may be regular polygons or not (for example, if it is approximately quadrilateral, it may be approximately rectangles, etc.), but it is preferable that they be regular polygons.

[0081] In the electrode configuration described above, the apparent area of ​​the porous metal substrate in a plan view is smaller than the apparent area of ​​the electrode mixture layer in a plan view. However, from the viewpoint of ensuring a better crack suppression effect in the electrode laminate, it is preferable that the apparent area of ​​the porous metal substrate in a plan view is 90% or less, and more preferably 80% or less, of the apparent area of ​​the electrode mixture layer in a plan view. However, if the apparent area of ​​the porous metal substrate in a plan view is made too small compared to the apparent area of ​​the electrode mixture layer in a plan view, the effect of the porous metal substrate in reducing the internal resistance of the electrochemical element may be reduced. Therefore, from the viewpoint of further reducing the internal resistance of the electrochemical element using the electrode laminate, it is preferable that the apparent area of ​​the porous metal substrate in a plan view is 50% or more, and more preferably 60% or more, of the apparent area of ​​the electrode mixture layer in a plan view.

[0082] In this specification, "apparent area of ​​the porous metal substrate in plan view" refers to the area of ​​the approximately polygonal shape formed by the outer edges of the porous metal substrate in plan view (a square in the case of the porous metal substrate shown in Figure 2, and approximately a pentagon in the case of the porous metal substrate shown in Figure 3). Similarly, "apparent area of ​​the electrode mixture layer in plan view" refers to the area of ​​the circle formed by the outer edges of the electrode mixture layer in plan view. Furthermore, in this specification, "apparent area of ​​the provisional molded body of the electrode mixture in plan view" refers to the area of ​​the shape formed by the outer edges of the provisional molded body of the electrode mixture in plan view.

[0083] The aforementioned "apparent area of ​​the porous metal substrate in plan view," the "apparent area of ​​the electrode mixture layer in plan view," and the "apparent area of ​​the provisional molded electrode mixture in plan view" described later can be measured using a dimensional measurement camera (such as the "XT-024" manufactured by Keyence Corporation). For example, since the outer edge of the electrode mixture layer is circular, three points can be selected from the outer edge of the electrode mixture layer, and the apparent area of ​​the electrode mixture layer in plan view can be measured as the area of ​​the circle passing through those points. The apparent area of ​​the provisional molded electrode mixture in plan view can also be measured in the same manner as the electrode mixture layer. In the case of a polygonal porous metal substrate, the outer edge can be recognized by edge detection, and the apparent area of ​​the porous metal substrate in plan view can be measured as the area of ​​the region enclosed by the lines forming the outer edge. The values ​​described in the examples below were obtained by the methods described herein.

[0084] In the electrode laminate, the thickness of the porous metal substrate and the thickness of the electrode mixture layer are determined by the maximum width in the thickness direction of the region where the porous metal substrate is visible and the region where the electrode mixture is visible, respectively, in an image obtained by observing the cross-section of the electrode in the thickness direction using SEM at a magnification of 50 to 1000 times. Furthermore, the thickness of the portion of the porous metal substrate embedded in the electrode mixture layer is determined by the maximum width in the thickness direction of the overlapping region of the porous metal substrate and the electrode mixture (the values ​​in the examples described later were obtained by these methods).

[0085] Furthermore, the proportion (area ratio) of the electrode mixture exposed on the electrode surface is determined by the ratio (A / B) of the total area of ​​the portion surrounded by the outer edge of the porous metal substrate in an image of the electrode surface observed by SEM at a magnification of 50 to 200 times, where the electrode mixture is exposed: A, and the apparent area of ​​the porous metal substrate in a plan view: B (the values ​​in the examples described later were obtained by this method).

[0086] In the electrode stack, a solid electrolyte layer is interposed between the first electrode and the second electrode.

[0087] Specific examples of the solid electrolyte constituting the solid electrolyte layer include the same solid electrolytes as those previously exemplified as those that can be included in the positive electrode mixture. Among the solid electrolytes exemplified above, sulfide-based solid electrolytes are preferred because they have high lithium ion conductivity and also have the function of improving the moldability of the solid electrolyte layer, and sulfide-based solid electrolytes having an argyrodite-type crystal structure are more preferred.

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

[0089] The thickness of the solid electrolyte layer is preferably 10 to 200 μm.

[0090] The electrode stack can be manufactured by a manufacturing method comprising the following steps 1 to 3.

[0091] In the first step, the electrode mixture is poured into a mold and pressurized to form a temporary molded body of the electrode mixture. The surface pressure during pressurization in the first step is preferably, for example, 30 to 500 MPa.

[0092] In the next second step, a porous metal substrate is placed on the temporary molded body of the electrode mixture formed in the first step, and in the following third step, the porous metal substrate is pressed and compressed toward the temporary molded body of the electrode mixture. This pressurization in the third step causes at least a portion of the porous metal substrate, including the end on the temporary molded body side of the electrode mixture, to be embedded within the temporary molded body of the electrode mixture, thereby forming an electrode mixture layer integrated with the porous metal substrate.

[0093] The third step of forming an electrode mixture layer integrated with a porous metal substrate is carried out in the following manner: (1) by stacking a provisional molded body of the electrode mixture for the first electrode, a provisional molded body of the electrode mixture for the first electrode with a porous metal substrate on it, or the first electrode, a solid electrolyte layer, or a provisional molded body of a solid electrolyte formed by pressure molding a solid electrolyte, and a provisional molded body of the electrode mixture for the second electrode with a porous metal substrate on it; or (2) by stacking a provisional molded body of the electrode mixture for the first electrode with a porous metal substrate on it, a solid electrolyte layer, or a provisional molded body of a solid electrolyte formed by pressure molding a solid electrolyte, a provisional molded body of the electrode mixture for the second electrode, or a provisional molded body of the electrode mixture for the second electrode with a porous metal substrate on it, or the second electrode.

[0094] In other words, in the above manufacturing method, when the second electrode is manufactured in the third step by forming an electrode mixture layer integrated with a porous metal substrate, this third step is carried out by applying pressure to the entire structure while the following are stacked: a temporary molded body for the first electrode, a temporary molded body for the first electrode with a porous metal substrate on it, or the first electrode as a finished product; a solid electrolyte layer as a finished product (independent membrane), or a temporary molded body of a solid electrolyte formed by pressure molding a solid electrolyte; and a temporary molded body for the second electrode with a porous metal substrate on it. This process simultaneously manufactures the second electrode and the electrode stack. In this case, if a temporary molded body for the first electrode (including the case with a porous metal substrate on it) is used, the first electrode can also be manufactured simultaneously in the third step, and if a temporary molded body of a solid electrolyte is used, the solid electrolyte layer can also be manufactured simultaneously in the third step.

[0095] Furthermore, in the above manufacturing method, if the first electrode is manufactured in the third step by forming an electrode mixture layer integrated with a porous metal substrate, this third step is carried out by applying pressure to the entire structure while the following are stacked: a temporary molded body for the first electrode on which the porous metal substrate is placed, a solid electrolyte layer which is a finished product (independent membrane), or a temporary molded body of a solid electrolyte formed by pressure molding a solid electrolyte, a temporary molded body for the second electrode, a temporary molded body for the second electrode on which the porous metal substrate is placed, or the finished second electrode. This process simultaneously manufactures the first electrode and the electrode stack. In this case, if a temporary molded body for the second electrode (including the case on which the porous metal substrate is placed) is used, the second electrode can also be manufactured simultaneously in the third step, and if a temporary molded body of a solid electrolyte is used, the solid electrolyte layer can also be manufactured simultaneously in the third step.

[0096] When forming an electrode mixture layer integrated with a porous metal substrate, the porous metal substrate is used in a substantially polygonal shape. After pressure molding, the size of the porous metal substrate in plan view is adjusted so that all corners of the substantially polygonal shape of the porous metal substrate are located between the outer edge of the electrode mixture layer and the concentric circles of the outer edge of the electrode mixture layer, which have a diameter of 0.7D, in a plan view.

[0097] Furthermore, when adjusting the size of the porous metal substrate in plan view, in order to adjust the ratio of the apparent area of ​​the porous metal substrate in plan view to the apparent area of ​​the electrode mixture layer in plan view to the above-mentioned preferred value, it is preferable to make the apparent area of ​​the porous metal substrate in plan view 88% or less, more preferably 78% or less, more preferably 48% or more, and more preferably 58% or more, of the apparent area of ​​the provisional molded body of the electrode mixture in plan view.

[0098] As described above, in the third step, the porous metal substrate is compressed in the thickness direction. From the viewpoint of more reliably forming the porous metal substrate and the electrode mixture layer, it is preferable that the thickness of the porous metal substrate after compression be 30% or less of the thickness before compression, more preferably 20% or less, and particularly preferable 10% or less. Furthermore, from the viewpoint of retaining a certain amount of electrode mixture in the voids of the porous metal substrate and increasing the bonding strength between the porous metal substrate and the electrode mixture layer, it is preferable that the thickness of the porous metal substrate after compression in the third step be 1% or more of the thickness before compression, and more preferably 2% or more.

[0099] In the third step, the surface pressure during pressurization is preferably 800 MPa or higher, more preferably 1000 MPa or higher, and particularly preferably 1200 MPa or higher, in order to sufficiently increase the density of the electrode mixture layer by compression molding the electrode mixture. There is no particular upper limit specified for the surface pressure during pressurization in the third step, but in a typical pressurization device, the upper limit is usually around 2000 MPa.

[0100] By going through the first to third steps described above, an electrode laminate can be obtained in which at least a portion of the porous metal substrate, including the end on the electrode mixture layer side (a certain range in the thickness direction from the end of the porous metal substrate), is embedded in the surface layer of the electrode mixture layer and integrated with the electrode mixture layer, and the other end of the porous metal substrate is exposed on the surface of the electrode.

[0101] Furthermore, if the surface pressure during pressurization in the third step becomes high, cracks may occur when the porous metal substrate is compressed. However, even if it is cut and fragments are generated, if the ends of these fragments are exposed on the electrode surface, it can contribute to reducing contact resistance.

[0102] When manufacturing an electrode laminate having a solid electrolyte layer, a step can be provided before the first step in which the solid electrolyte is placed in a mold and pressurized to form a provisional solid electrolyte body. The electrode mixture can then be placed on the provisional solid electrolyte body formed in this step, and the first step can be carried out thereafter.

[0103] The surface pressure applied during pressurization to form a provisional molded body of the solid electrolyte is preferably, for example, 30 to 120 MPa.

[0104] <Electrochemical Element> The electrochemical element of the present invention comprises an outer casing and an electrode stack of the present invention sealed inside the outer casing, wherein the outer casing has a conductive path that leads from the inside to the outside of the outer casing, and the porous metal substrate on the surface of the electrodes of the electrode stack is brought into contact with the conductive path, thereby creating electrical conductivity between the electrodes and the conductive path.

[0105] Figure 4 shows a schematic cross-sectional view of an example of the electrochemical element of the present invention. The electrochemical element 100 shown in Figure 4 is constructed by enclosing an electrode stack 140, which has a first electrode 110, a second electrode 120, and a solid electrolyte layer 130 interposed between them, within an outer casing formed by an outer container 160 and a lid 170.

[0106] External terminals 180 and 190 are provided on the lower surface of the outer container 160 in the figure for electrically connecting the electrochemical element 100 to the application equipment. External terminal 180 is electrically connected to the first electrode 110 in the electrode stack 140 via a conductive path 181. Furthermore, external terminal 190 is electrically connected to the second electrode 120 in the electrode stack 140 via a lead 200 and a conductive path 191.

[0107] The first electrode 110 has an electrode mixture layer 111 and a porous metal substrate 112, and the entire porous metal substrate 112, including the end on the electrode mixture layer 111 side, is embedded in the surface layer of the electrode mixture layer 111. That is, the entire area where the porous metal substrate 112 is located corresponds to the region where the electrode mixture layer and the porous metal substrate coexist, i.e., the surface layer of the electrode mixture layer. Furthermore, in the first electrode 110, the end of the porous metal substrate 112 opposite to the electrode mixture layer 111 side (the lower end in Figure 4) is exposed on the surface. The dotted line in the first electrode 110 indicates the boundary between the region in the electrode mixture layer 111 where the porous metal substrate does not coexist and the region where the electrode mixture layer and the porous metal substrate coexist, and corresponds to the end of the porous metal substrate 112 on the electrode mixture layer 111 side.

[0108] The second electrode 120 has an electrode mixture layer 121 and a porous metal substrate 122, and the entire porous metal substrate 122, including the end on the electrode mixture layer 121 side, is embedded in the surface layer of the electrode mixture layer 121. That is, the entire area where the porous metal substrate 122 is located corresponds to the region where the electrode mixture layer and the porous metal substrate coexist, i.e., the surface layer of the electrode mixture layer. Furthermore, in the second electrode 120, the end of the porous metal substrate 122 opposite to the electrode mixture layer 121 side (the upper end in Figure 4) is exposed on the surface. The dotted line in the second electrode 120 indicates the boundary between the region in the electrode mixture layer 121 where the porous metal substrate does not coexist and the region where the electrode mixture layer and the porous metal substrate coexist, and corresponds to the end of the porous metal substrate 122 on the electrode mixture layer 121 side.

[0109] A conductive sheet (such as a metal foil or a foamed porous metal body) 150 is placed on the surface of the porous metal substrate 112 of the first electrode 110 (the surface opposite to the electrode mixture layer 121 side). The first electrode 110 is electrically connected to the conductive sheet 150 by contact with the porous metal substrate 112, and this conductive sheet 150 is electrically connected to the conductive path 181. In other words, this conductive sheet 150 also constitutes a conductive path for the first electrode 110.

[0110] Furthermore, in the electrochemical element 100 shown in Figure 4, a spacer 210 is placed between the lead 200 and the cover 170, which has the effect of pressing the electrode stack 140 toward the conductive sheet 150. Due to the action of this spacer 210, the electrical connection between the lead 200 and the second electrode 120 and conductive path 191, the electrical connection between the first electrode 110 and the conductive sheet 150, and the electrical connection between the conductive sheet 150 and the conductive path 181 are improved. A rubber plate or a metal spring (such as a leaf spring) can be used for the spacer 210.

[0111] The casing of the electrochemical element may consist of a case having an outer container and a sealing body, as shown in Figure 4. The outer container can be made of ceramics or resin. The lid can be made of ceramics, resin, or metal (such as iron-nickel alloys or iron-nickel-cobalt alloys). Furthermore, in the outer container, the external terminals and the conductive paths connecting the electrodes of the electrode stack to the external terminals can be made of metals such as manganese, cobalt, nickel, copper, molybdenum, silver, palladium, tungsten, platinum, gold, or alloys containing these metals.

[0112] The outer container and the lid can be sealed by bonding them together with adhesive. Alternatively, when using a metal lid, the side wall of the recess in the outer container that faces the lid can be constructed of metal (such as an iron-nickel alloy or an iron-nickel-cobalt alloy) and then welded to the lid, or sealed by brazing with an alloy such as gold-tin (Au-Sn).

[0113] Furthermore, if both the outer container and the lid are made of ceramics, they can also be sealed by welding them with low-melting-point glass.

[0114] Furthermore, the casing of the electrochemical element is not limited to the case shown in Figure 4, as long as it has a conductive path that leads from the inside to the outside of the casing, and the porous metal substrate on the surface of the electrode of the electrode stack is in contact with the conductive path to establish electrical conductivity between the electrode and the conductive path. For example, a case consisting of an outer can and a sealed can may be used. Electrochemical elements with such a case as their casing are coin-shaped (button-shaped).

[0115] In cases where the casing of an electrochemical element consists of an outer can and a sealing can, examples include cases where the outer can and the sealing can are crimped together via a gasket, as well as cases where the outer can and the sealing can are bonded together with resin.

[0116] Stainless steel can be used for the outer casing and sealing can. Polypropylene and nylon can be used as gasket materials, and if heat resistance is required due to the application of the electrochemical element, heat-resistant resins with a melting point exceeding 240°C can also be used. Examples of such heat-resistant resins include fluororesins (such as tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA)), polyphenylene ether (PPE), polysulfone (PSF), polyarylate (PAR), polyethersulfone (PES), polyphenylene sulfide (PPS), and polyetheretherketone (PEEK). Furthermore, when the electrochemical element is used in applications requiring heat resistance, glass hermetic seals can be used for sealing.

[0117] The shape of the outer casing of the electrochemical element in plan view may be circular, or it may be a polygon such as a square or rectangle.

[0118] The present invention will be described in detail below based on examples. However, the following examples are not intended to limit the present invention.

[0119] (Example 1) Lithium titanate (Li) with an average particle size of 2 μm ４ Ti ５ O １２ (negative electrode active material) and a sulfide-based solid electrolyte (Li) with an average particle size of 0.7 μm ６ PS ５ A negative electrode mixture was prepared by mixing Cl) and graphene (a conductive additive) in a mass ratio of 50:41:9.

[0120] Also, LiNbO ３ LiCoO with an average particle size of 5 μm, on which a coating layer is formed. ２ (Positive electrode active material) and a sulfide-based solid electrolyte (Li) with an average particle size of 0.7 μm ６ PS ５ A positive electrode mixture was prepared by mixing Cl) and graphene in a mass ratio of 65:30.7:4.3.

[0121] Next, a sulfide-based solid electrolyte (Li) with an average particle size of 0.7 μm ６ PS ５The Cl powder was placed in a powder molding die, and preliminary molding was performed using a press machine at a surface pressure of 70 MPa to form a preliminary molded body of the solid electrolyte layer. Furthermore, the negative electrode mixture was placed on the upper surface of the preliminary molded body of the solid electrolyte layer and preliminary molding was performed at a surface pressure of 50 MPa to form a preliminary molded body of the negative electrode on top of the preliminary molded body of the solid electrolyte layer.

[0122] Next, a nickel-based foamed metal porous material [Nickel-based "Cellmet" (registered trademark)] from Sumitomo Electric Industries, Ltd., cut into a regular pentagon inscribed in a circle with a diameter of 7.1 mm (thickness: 1.2 mm, porosity: 98%), was placed on the provisional molded body of the negative electrode formed on the provisional molded body of the solid electrolyte layer, and a porous metal substrate for the negative electrode was formed as an integrated product of the provisional molded body of the solid electrolyte layer, the provisional molded body of the negative electrode mixture, and the porous metal substrate for the negative electrode.

[0123] Through the aforementioned pressure molding, the foamed porous metal body was compressed and embedded within the negative electrode mixture in the provisional molded body of the negative electrode mixture, and a provisional molded body of the negative electrode mixture was obtained in which a porous metal substrate was embedded in the surface layer.

[0124] Furthermore, after inverting the mold, the positive electrode mixture was placed on the upper surface of the solid electrolyte temporary molded body inside the mold (the side opposite to the side with the negative electrode temporary molded body) and molded with a surface pressure of 50 MPa to form a positive electrode temporary molded body on top of the solid electrolyte temporary molded body.

[0125] Next, a piece of the same nickel foamed porous metal material used for the negative electrode was cut and placed on a provisional positive electrode formed on a solid electrolyte layer. Pressurized molding was then performed at a surface pressure of 1400 MPa to obtain an electrode laminate having a positive electrode in which a regular pentagonal porous metal substrate is embedded in the surface layer of the positive electrode mixture layer, and a negative electrode having a solid electrolyte layer and a regular pentagonal porous metal substrate embedded in the surface layer of the negative electrode mixture layer.

[0126] In the obtained electrode laminate, the thickness of the negative electrode mixture layer, the thickness of the porous metal substrate, and the thickness of the portion of the porous metal substrate embedded in the negative electrode mixture layer were 1400 μm, 60 μm (5% of the thickness of the porous metal substrate before use in the negative electrode), and 60 μm (100% of the total thickness of the porous metal substrate), respectively. Furthermore, the area ratio of the exposed negative electrode mixture portion within the area surrounded by the outer edge of the porous metal substrate on the surface of the negative electrode was 7%. In addition, in a plan view, the vertices of the porous metal substrate of the negative electrode were located in the concentric circles of the outer edge of the electrode mixture layer with a diameter of 0.93D to 0.97D. That is, all vertices were located between the outer edge of the electrode mixture layer and the concentric circles of the outer edge of the electrode mixture layer with a diameter of 0.7D, and the apparent area of ​​the porous metal substrate of the negative electrode in a plan view was 72% of the apparent area of ​​the negative electrode mixture layer in a plan view.

[0127] Furthermore, in the obtained electrode laminate, the thickness of the positive electrode mixture layer, the thickness of the porous metal substrate, and the thickness of the portion of the porous metal substrate embedded in the positive electrode mixture layer were 800 μm, 60 μm (5% of the thickness of the porous metal substrate before use in the positive electrode), and 60 μm (100% of the total thickness of the porous metal substrate), respectively. In addition, the area ratio of the exposed positive electrode mixture portion within the portion of the positive electrode surface surrounded by the outer edge of the porous metal substrate was 7%. Moreover, in a plan view, the vertices of the porous metal substrate of the positive electrode were located in the concentric circles of the outer edge of the electrode mixture layer with a diameter of 0.93D to 0.97D. That is, all vertices were located between the outer edge of the electrode mixture layer and the concentric circles of the outer edge of the electrode mixture layer with a diameter of 0.7D, and the apparent area of ​​the porous metal substrate of the positive electrode in a plan view was 72% of the apparent area of ​​the positive electrode mixture layer in a plan view.

[0128] A concave container (2.5 mm deep in ceramics) had a cross-sectional structure similar to that shown in Figure 4, was made of ceramics, and had a seal ring made of iron-nickel-cobalt alloy placed on the upper part of the side wall. A piece of nickel-based foamed porous metal material, the same as that used for the positive and negative electrodes, cut to a diameter of 7.25 mm, was placed on the inner bottom surface of the container. The electrode stack was then placed on top of the lead (Ni foil) on the negative electrode of the electrode stack, and a rubber sheet (spacer) with a thickness of 400 μm was placed on top of that. Subsequently, a lid made of iron-nickel-cobalt alloy was placed on the side wall of the recess of the outer container, and the outer container was sealed by welding the lid to the outer container while compressing the rubber sheet in the thickness direction, thereby obtaining an all-solid-state secondary battery. In the obtained all-solid-state secondary battery, the rubber sheet spacer was compressed in the thickness direction, and as a result, the electrode stack pressed against the conductive sheet made of foamed porous metal material. Furthermore, the thickness of the conductive sheet in the all-solid-state secondary battery was 200 μm.

[0129] Example 2 An electrode stack was formed in the same manner as in Example 1, except that the shape of the foamed metal porous material used for the positive and negative electrodes was changed to a regular pentagon inscribed in a circle with a diameter of 6.2 mm. An all-solid-state secondary battery was then manufactured in the same manner as in Example 1, except that this electrode stack was used.

[0130] In the electrode stack used in the battery of Example 2, in both the positive and negative electrodes, the porous metal substrates, in a plan view, had their vertices located in the concentric circles of the outer edge of the electrode mixture layer with a diameter of 0.80D to 0.85D. That is, all vertices were located between the outer edge of the electrode mixture layer and the concentric circles of the outer edge of the electrode mixture layer with a diameter of 0.7D. The apparent area of ​​the porous metal substrate of the negative electrode in a plan view was 55% of the apparent area of ​​the negative electrode mixture layer in a plan view, and the apparent area of ​​the porous metal substrate of the positive electrode in a plan view was 55% of the apparent area of ​​the positive electrode mixture layer in a plan view.

[0131] Comparative Example 1: An electrode stack was formed in the same manner as in Example 1, except that the shape of the foamed metal porous material used for the positive and negative electrodes was changed to a circle with a diameter of 7.15 mm. An all-solid-state secondary battery was then manufactured in the same manner as in Example 1, except that this electrode stack was used.

[0132] In the electrode laminate used in the battery of Comparative Example 1, the apparent area of ​​the porous metal substrate of the negative electrode in a plan view was 95% of the apparent area of ​​the negative electrode mixture layer in a plan view, and the apparent area of ​​the porous metal substrate of the positive electrode in a plan view was 95% of the apparent area of ​​the positive electrode mixture layer in a plan view.

[0133] Comparative Example 2: An electrode stack was formed in the same manner as in Example 1, except that the shape of the foamed metal porous material used for the positive and negative electrodes was changed to a circle with a diameter of 6.2 mm. An all-solid-state secondary battery was then manufactured in the same manner as in Example 1, except that this electrode stack was used.

[0134] In the electrode laminate used in the battery of Comparative Example 2, the apparent area of ​​the porous metal substrate of the negative electrode in a plan view was 72% of the apparent area of ​​the negative electrode mixture layer in a plan view, and the apparent area of ​​the porous metal substrate of the positive electrode in a plan view was 72% of the apparent area of ​​the positive electrode mixture layer in a plan view.

[0135] For 100 all-solid-state secondary batteries each of the examples and comparative examples, the electrode stacks (the positive electrode composite layer, negative electrode composite layer, and solid electrolyte layer) were observed with an electron microscope, and the number of cracks was counted. The results are shown in Table 1. Note that the "percentage of apparent area in plan view" in Table 1 refers to "the ratio of the apparent area of ​​the porous metal substrate in the electrodes (positive electrode and negative electrode) in a plan view to the apparent area of ​​the electrode composite layer in a plan view."

[0136]

[0137] As can be seen from Table 1, in the all-solid-state secondary batteries of Examples 1 and 2, which used electrode stacks in which the porous metal substrate had a substantially polygonal (regular pentagonal) shape in plan view, crack occurrence was suppressed compared to the all-solid-state secondary batteries of Comparative Examples 1 and 2, which used electrode stacks in which the porous metal substrate had a circular shape.

[0138] Next, for 100 all-solid-state secondary batteries each from the examples and comparative examples, the side portions of the electrode stacks were observed using a Keyence VHX-X1 digital microscope equipped with an EA-300 elemental analysis head, and elemental analysis of the side portions was performed. The number of Ni elements detected was counted, and these were determined to be Ni metal powder (Ni contamination). The results are shown in Table 2.

[0139]

[0140] As can be seen from Table 2, in the all-solid-state secondary batteries of Examples 1 and 2, which used electrode stacks in which the porous metal substrate had a roughly polygonal (regular pentagonal) shape in plan view, the number of Ni elements detected was lower compared to the all-solid-state secondary batteries of Comparative Examples 1 and 2, which used electrode stacks in which the porous metal substrate had a circular shape. This is thought to be because the generation of Ni metal powder was suppressed.

[0141] The present invention can also be implemented in forms other than those described herein, without departing from its spirit. The embodiments disclosed herein are examples, and the present invention is not limited to these embodiments. The scope of the present invention shall be interpreted in accordance with the claims attached, which take precedence over the description herein, and all modifications within the scope equivalent to the claims are included in the claims.

[0142] The electrochemical element of the present invention can be applied to the same applications as known electrochemical elements. Furthermore, the electrode laminate of the present invention can constitute the electrochemical element of the present invention.

[0143] 10 Porous metal substrate 11 Electrode mixture 100 Electrochemical element 110 First electrode 111 Electrode mixture layer 112 Porous metal substrate 120 Second electrode 121 Electrode mixture layer 122 Porous metal substrate 130 Solid electrolyte layer 140 Electrode stack 150 Conductive sheet 160 Outer container 170 Lid 180, 190 External terminals 181, 191 Conductive path 200 Lead 210 Spacer

Claims

1. An electrode laminate having a first electrode, a second electrode, and a solid electrolyte layer interposed between them, wherein at least one of the first electrode and the second electrode has an electrode mixture layer formed by pressure molding of a powdery electrode mixture, the outer edge of which is circular in diameter D in a plan view, and a sheet-like porous metal substrate, wherein at least a portion of the porous metal substrate, including the end on the electrode mixture layer side, is embedded in the surface layer of the electrode mixture layer and integrated with the electrode mixture layer, the other end of the porous metal substrate is exposed on the surface of the electrode, and the porous metal substrate is substantially polygonal in a plan view, and all corners of the substantially polygon are located between the outer edge of the electrode mixture layer and a concentric circle of the outer edge of the electrode mixture layer with a diameter of 0.7D.

2. The electrode laminate according to claim 1, wherein the plan view shape of the porous metal substrate is (a) a polygon, (b) a shape in which at least one vertex of the polygon is curved, (c) a shape in which at least one side of the polygon is curved, or (d) a shape in which at least one vertex of the polygon is curved and at least one side is curved.

3. The electrode laminate according to claim 1, wherein the planar shape of the porous metal substrate is a polygon with 4 to 8 vertices.

4. The electrode stack according to claim 1, wherein the substantially polygonal shape is a regular polygon.

5. The electrode laminate according to claim 1, wherein the apparent area of ​​the porous metal substrate in a plan view is 90% or less of the apparent area of ​​the electrode mixture layer in a plan view.

6. The electrode laminate according to claim 1, wherein the porous metal substrate is a compressed foamed porous metal body.

7. The electrode laminate according to claim 1, wherein the thickness of the porous metal substrate is 30% or less of the thickness of the electrode mixture layer.

8. A method for manufacturing an electrode laminate according to claim 1, comprising: a first step of forming a provisional body of the electrode having an electrode mixture layer and a sheet-like porous metal substrate by pouring the electrode mixture into a mold and applying pressure; a second step of placing a sheet-like porous metal substrate, which has a substantially polygonal shape in plan view, on the provisional body of the electrode mixture formed in the first step, such that in plan view, the outer edge of the porous metal substrate is inward from the outer edge of the provisional body of the electrode mixture; and a third step of pressing and compressing the porous metal substrate toward the provisional body of the electrode mixture so that at least a portion of the porous metal substrate, including the end on the electrode mixture side, is embedded in the electrode mixture, thereby forming an electrode mixture layer integrated with the porous metal substrate. A method for manufacturing an electrode laminate, characterized in that the third step is carried out in a state in which the following are laminated: a provisional molded body of the electrode mixture for the first electrode, a provisional molded body of the electrode mixture for the first electrode on which the porous metal substrate is placed, or the first electrode, the solid electrolyte layer or a provisional molded body of a solid electrolyte obtained by pressure molding a solid electrolyte, and a provisional molded body of the electrode mixture for the second electrode on which the porous metal substrate is placed; or the third step is carried out in a state in which the following are laminated: a provisional molded body of the electrode mixture for the first electrode on which the porous metal substrate is placed, the solid electrolyte layer or a provisional molded body of a solid electrolyte obtained by pressure molding a solid electrolyte, a provisional molded body of the electrode mixture for the second electrode on which the porous metal substrate is placed, or the second electrode.

9. The method for manufacturing an electrode laminate according to claim 8, wherein the apparent area of ​​the porous metal substrate in a plan view is 88% or less of the apparent area of ​​the provisional molded body of the electrode mixture in a plan view.

10. The method for manufacturing an electrode laminate according to claim 8, wherein a foamed metal porous body is used as the porous metal substrate.

11. The method for manufacturing an electrode laminate according to claim 8, comprising the step of putting a solid electrolyte into a mold and pressurizing it to form a temporary molded body of the solid electrolyte before the first step, placing the electrode mixture on the temporary molded body of the solid electrolyte and performing the first step, and performing the third step in a state in which the temporary molded body of the electrode mixture for the first electrode, the temporary molded body of the electrode mixture for the first electrode on which the porous metal substrate is placed or the first electrode, the temporary molded body of the solid electrolyte, and the temporary molded body of the electrode mixture for the second electrode on which the porous metal substrate is placed are stacked, or the method for manufacturing an electrode laminate according to claim 8, comprising the step of putting a solid electrolyte into a mold and pressurizing it before the first step, and performing the third step in a state in which the temporary molded body of the electrode mixture for the first electrode on which the porous metal substrate is placed or the second electrode are stacked.

12. The method for manufacturing an electrode laminate according to claim 8, wherein in the third step, the thickness of the porous metal substrate is 30% or less of the thickness before compression.

13. An electrochemical element comprising an outer casing and an electrode laminate according to any one of claims 1 to 7 sealed inside the outer casing, wherein the outer casing has a conductive path leading from the inside to the outside, and the porous metal substrate on the surface of the electrodes of the electrode laminate is brought into contact with the conductive path, thereby creating electrical conductivity between the electrodes and the conductive path.

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