Solid state battery and manufacturing method of the solid state battery

Abstract

To realize a solid state battery with high quality.SOLUTION: A solid state battery 1A includes: a lamination body 14 in which a positive electrode layer 11 and a negative electrode layer 12 are laminated via an electrolyte layer 13 to a first direction D1; and an insulation layer 15 that covers them, and contains a battery main body 10 containing a first end surface 10a which is faced to a first side D2a of a second direction D2, and of which one part of the positive electrode layer 11 is exposed from the insulation layer 15, and a second end surface 10b which is faced to a second side D2b of the second direction D2, and in which the one part of the negative electrode layer 12 is exposed from the insulation layer 15, In addition, the solid state battery 1A contains: a first external electrode layer 21 that covers the first end surface 10a, and is connected to the positive electrode layer 11; a first metal layer 22 that covers them; a second external electrode layer 31 that covers the second end surface 10b, and is connected to the negative electrode layer 12; and a second metal layer 32 that covers them. The first external electrode layer 21 contains Cu in the first front surface part 21a on the first metal layer 22 side, and the second external electrode layer 31 contains Ag in the second front layer part 31a on the second metal layer 32 side.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a solid-state battery and a method for manufacturing a solid-state battery. [Background technology]

[0002] Regarding solid-state batteries, there is known a technology in which external electrodes electrically connected to the positive electrode layer and the negative electrode layer of a solid-state battery laminate including a positive electrode layer, a negative electrode layer, and a solid electrolyte interposed between them contain at least one element selected from the group consisting of Cu (copper), Ag (silver), Ni (nickel), Ti (titanium), Cr (chromium), Pt (platinum), and Pd (palladium) (Patent Document 1).

[0003] Furthermore, with regard to electronic components such as multilayer ceramic capacitors, a technology is known in which an external nickel layer is provided on an end face where the internal nickel electrode layer of a laminate body having an internal layer portion in which dielectric layers and internal nickel electrode layers are alternately laminated, and on the outside of the external nickel layer, a thermosetting resin layer containing a metal filler such as copper or an external copper electrode layer is provided (Patent Documents 2 and 3). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2021 / 070601 Brochure [Patent Document 2] JP 2022-14534 A [Patent Document 3] Patent Publication No. 2022-14536 Summary of the Invention [Problem to be solved by the invention]

[0005] A known solid-state battery is one in which an external electrode layer connected to the exposed portion of the electrode layer and a metal layer covering the external electrode layer are provided on end faces of a laminate in which positive and negative electrode layers (positive and negative electrode layers) are stacked with an electrolyte layer interposed therebetween. For example, the external electrode layer is formed using a paste containing a conductive material, and a metal layer is formed to cover the external electrode layer using a plating method or the like.

[0006] In such a solid-state battery, for example, when the external electrode layer is formed using a paste containing Ag as a conductive material, if the coverage with the metal layer is insufficient, migration of Ag from the external electrode layer on the positive electrode side may occur due to the influence of moisture in the air when electricity is applied. Also, for example, when the external electrode layer is formed using a paste containing Cu as a conductive material, discoloration may occur in the metal layer covering the external electrode layer on the negative electrode side or in the external electrode layer itself when electricity is applied. The occurrence of such migration or discoloration may lead to a deterioration in the quality of the solid-state battery.

[0007] In one aspect, the present invention aims to realize a high-quality solid-state battery. [Means for solving the problem]

[0008] In one aspect, there is provided a solid-state battery including: a battery main body having a laminate in which a positive electrode layer and a negative electrode layer are laminated in a first direction with an electrolyte layer interposed therebetween; and an insulating layer covering the laminate, the battery main body having a first end face facing a first side in a second direction perpendicular to the first direction and a part of the positive electrode layer is exposed from the insulating layer, and a second end face facing a second side opposite the first side in the second direction and a part of the negative electrode layer is exposed from the insulating layer; a first external electrode layer covering the first end face and connected to the positive electrode layer; a second external electrode layer covering the second end face and connected to the negative electrode layer; a first metal layer covering the first external electrode layer; and a second metal layer covering the second external electrode layer, wherein the first external electrode layer contains Cu in a first surface layer portion on the first metal layer side, and the second external electrode layer contains Ag in a second surface layer portion on the second metal layer side.

[0009] In another aspect, a method for producing such a solid-state battery is provided. Effect of the Invention

[0010] On the one hand, it will be possible to realize high-quality solid-state batteries. [Brief description of the drawings]

[0011] [Figure 1] 1A and 1B are diagrams illustrating a first example of a solid-state battery. [Diagram 2] 11A and 11B are diagrams illustrating a second example of a solid-state battery. [Diagram 3] 1A to 1C are diagrams illustrating a first example of a solid-state battery according to an embodiment. [Figure 4] 6A to 6C are diagrams illustrating a second example of a solid-state battery according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] FIG. 1 is a diagram for explaining a first example of a solid-state battery. FIG. 1(A) is a schematic external perspective view of a main part of the first example of the solid-state battery. FIG. 1(B) is a schematic cross-sectional view of a main part of the first example of the solid-state battery. FIG. 1(B) is an example of a schematic cross-sectional view taken along line L1 in FIG. 1(A).

[0013] 1A and 1B is an example of a lithium ion battery. The solid-state battery 100A includes a battery body 110, and a positive terminal 120A and a negative terminal 130A provided at both ends of the battery body 110, respectively.

[0014] 1(B), the battery body 110 has a laminate 114 in which a positive electrode layer 111 and a negative electrode layer 112 are laminated in a first direction D1 with an electrolyte layer 113 interposed therebetween, and an insulating layer 115 that covers the laminate 114. The battery body 110 has a first end surface 110a that faces a first side D2a in a second direction D2 perpendicular to the first direction D1 and where a part (side surface) of the positive electrode layer 111 is exposed from the insulating layer 115, and a second end surface 110b that faces a second side D2b opposite to the first side D2a in the second direction D2 and where a part (side surface) of the negative electrode layer 112 is exposed from the insulating layer 115.

[0015] The positive electrode terminal 120A includes a first external electrode layer 121A covering the first end face 110a of the battery body 110 and connected to a part of the positive electrode layer 111 exposed from the first end face 110a, and a first metal layer 122A covering the surface. The negative electrode terminal 130A includes a second external electrode layer 131A covering the second end face 110b of the battery body 110 and connected to a part of the negative electrode layer 112 exposed from the second end face 110b, and a second metal layer 132A covering the surface.

[0016] When the solid-state battery 100A is charged, lithium ions are conducted from the positive electrode layer 111 to the negative electrode layer 112 via the electrolyte layer 113 and are taken in, and when the solid-state battery 100A is discharged, lithium ions are conducted from the negative electrode layer 112 to the positive electrode layer 111 via the electrolyte layer 113 and are taken in. In the solid-state battery 100A, charging and discharging operations are realized by such lithium ion conduction caused by predetermined current application to the positive electrode terminal 120A and the negative electrode terminal 130A connected to the positive electrode layer 111 and the negative electrode layer 112, respectively.

[0017] Here, the first external electrode layer 121A of the positive electrode terminal 120A and the second external electrode layer 131A of the negative electrode terminal 130A are formed by, for example, applying a paste containing Ag as the entire conductive material or as the main component to the end portions of the first end face 110a side and the second end face 110b side of the battery body 110, respectively, and curing or baking them by a predetermined heat treatment. The first metal layer 122A of the positive electrode terminal 120A and the second metal layer 132A of the negative electrode terminal 130A are formed by, for example, forming a Ni layer on the surface of the first external electrode layer 121A and the second external electrode layer 131A, respectively, by a plating method, and further forming a Sn (tin) layer on the surface of the Ni layer by a plating method. The first metal layer 122A and the second metal layer 132A make it easy to mount the solid-state battery 100A on other components such as a circuit board. The first metal layer 122A and the second metal layer 132A have a relatively high moisture barrier property. Therefore, the first metal layer 122A and the second metal layer 132A can function as protective layers for protecting the first external electrode layer 121A and the second external electrode layer 131A from external moisture, respectively.

[0018] However, during the charge / discharge operation of the solid-state battery 100A, the following may occur with a predetermined current flow to the positive terminal 120A and the negative terminal 130A. For example, if the first external electrode layer 121A is not sufficiently covered by the first metal layer 122A on the positive terminal 120A side, Ag contained as a conductive material in the first external electrode layer 121A may repeatedly dissolve and precipitate due to the influence of moisture in the air, and may grow as migration 200 on the surface of the battery body 110 as shown in FIG. 1(A) and FIG. 1(B). Ag is one of the materials in which such migration 200 is relatively likely to occur. If the migration 200 occurring on the positive terminal 120A side extends to the negative terminal 130A side, it may cause a short circuit of the solid-state battery 100A. The occurrence of migration 200 may be one of the causes of deterioration in the quality of the solid-state battery 100A.

[0019] FIG. 2 is a diagram for explaining a second example of a solid-state battery. FIG. 2(A) is a schematic perspective view of the exterior of a main part of the second example of the solid-state battery. FIG. 2(B) is a schematic cross-sectional view of a main part of the second example of the solid-state battery. FIG. 2(B) is an example of a schematic cross-sectional view taken along line L2 in FIG. 2(A).

[0020] The solid-state battery 100B shown in Figures 2(A) and 2(B) is an example of a lithium-ion battery. The solid-state battery 100B includes a battery body 110 similar to the solid-state battery 100A, and a positive terminal 120B and a negative terminal 130B provided at both ends of the battery body 110, respectively.

[0021] The positive electrode terminal 120B includes a first external electrode layer 121B covering the first end face 110a of the battery body 110 and connected to a part of the positive electrode layer 111 exposed from the first end face 110a, and a first metal layer 122B covering the surface. The negative electrode terminal 130B includes a second external electrode layer 131B covering the second end face 110b of the battery body 110 and connected to a part of the negative electrode layer 112 exposed from the second end face 110b, and a second metal layer 132B covering the surface.

[0022] In the solid-state battery 100B, the first external electrode layer 121B of the positive electrode terminal 120B and the second external electrode layer 131B of the negative electrode terminal 130B are formed by, for example, applying a paste containing Cu as the entire conductive material or mainly Cu to the ends of the first end face 110a side and the second end face 110b side of the battery body 110, respectively, and curing or baking them by a predetermined heat treatment. In this respect, the solid-state battery 100B differs from the solid-state battery 100A. The first metal layer 122B of the positive electrode terminal 120B and the second metal layer 132B of the negative electrode terminal 130B are formed, for example, by forming a Ni layer on the surface of the first external electrode layer 121B and the second external electrode layer 131B by plating, respectively, as in the solid-state battery 100A, and further forming a Sn layer on the surface of the Ni layer by plating.

[0023] In the solid-state battery 100B, Cu, which is a type of material that is less likely to cause migration than Ag, is used as a conductive material for both the first external electrode layer 121B of the positive electrode terminal 120B and the second external electrode layer 131B of the negative electrode terminal 130B. Therefore, in the solid-state battery 100B, during charging and discharging operations realized by passing a predetermined current through the positive electrode terminal 120B and the negative electrode terminal 130B, the occurrence of Ag migration 200 as shown in Figs. 1(A) and 1(B) is suppressed on the positive electrode terminal 120B side.

[0024] However, in a solid-state battery 100B in which Cu is used as a conductive material in the second external electrode layer 131B on the negative electrode terminal 130B side, discoloration (or deterioration) 210 may occur in the second metal layer 132B covering the second external electrode layer 131B or in the second external electrode layer 131B as shown in Figures 2(A) and 2(B) due to charging and discharging operations. The discoloration 210 occurring on the negative electrode terminal 130B side may cause a poor appearance of the solid-state battery 100B and a decrease in the current carrying performance of the negative electrode terminal 130B. The occurrence of discoloration 210 may be one of the causes of a decrease in the quality of the solid-state battery 100B.

[0025] As described above, when Ag is used as a conductive material for both the first external electrode layer 121A on the positive terminal 120A side and the second external electrode layer 131A on the negative terminal 130A side as in the solid-state battery 100A shown in Figs. 1(A) and 1(B), migration 200 of Ag may occur on the positive terminal 120A side. In addition, when Cu is used as a conductive material for both the first external electrode layer 121B on the positive terminal 120B side and the second external electrode layer 131B on the negative terminal 130B side as in the solid-state battery 100B shown in Figs. 2(A) and 2(B), discoloration 210 may occur on the negative terminal 130B side. The occurrence of such migration 200 and discoloration 210 may lead to a deterioration in the quality of the solid-state battery 100A and the solid-state battery 100B.

[0026] In view of the above, a configuration as shown in the following embodiment is adopted to realize a high-quality solid-state battery in which the occurrence of migration on the positive electrode terminal side and discoloration (or deterioration) on the negative electrode terminal side during charging and discharging (energization) is suppressed.

[0027] Fig. 3 is a diagram for explaining a first example of a solid-state battery according to an embodiment. Fig. 3(A) is a schematic perspective view of the exterior of a main part of the first example of a solid-state battery according to an embodiment. Fig. 3(B) is a schematic cross-sectional view of a main part of the first example of a solid-state battery according to an embodiment. Fig. 3(B) is an example of a schematic cross-sectional view taken along line L3 in Fig. 3(A).

[0028] The solid-state battery 1 shown in Figures 3(A) and 3(B) is an example of a lithium-ion battery. The solid-state battery 1 includes a battery body 10, a positive electrode terminal 20, and a negative electrode terminal 30. The battery body 10 is also referred to as a "battery element," "battery body," or "body" of the solid-state battery 1. The positive electrode terminal 20 and the negative electrode terminal 30 are provided at both ends of the battery body 10, respectively.

[0029] As shown in Fig. 3(B), the battery body 10 has a laminate 14 in which the positive electrode layer 11 and the negative electrode layer 12 are laminated in the first direction D1 with the electrolyte layer 13 interposed therebetween, and an insulating layer 15 that covers the laminate 14. The number of layers of the positive electrode layer 11, the negative electrode layer 12, and the electrolyte layer 13 included in the laminate 14 of the battery body 10 is not limited to those shown in Fig. 3(B) (and Fig. 4 described later). The positive electrode layer 11 and the negative electrode layer 12 are provided so as to partially overlap each other with the electrolyte layer 13 interposed therebetween, and are provided so that a part (side surface) of each of them is exposed from the insulating layer 15. The battery body 10 has a first end face 10a facing a first side D2a in a second direction D2 perpendicular to the first direction D1, where a portion of the positive electrode layer 11 is exposed from the insulating layer 15, and a second end face 10b facing a second side D2b opposite the first side D2a in the second direction D2, where a portion of the negative electrode layer 12 is exposed from the insulating layer 15.

[0030] The positive electrode terminal 20 includes a first external electrode layer 21 that covers the first end face 10a of the battery body 10 and is connected to a part of the positive electrode layer 11 exposed from the first end face 10a, and a first metal layer 22 that covers the surface thereof. The first external electrode layer 21 is electrically connected to the positive electrode layer 11, and the first metal layer 22 is electrically connected to the first external electrode layer 21. Further, the negative electrode terminal 30 includes a second external electrode layer 31 that covers the second end face 10b of the battery body 10 and is connected to a part of the negative electrode layer 12 exposed from the second end face 10b, and a second metal layer 32 that covers the surface thereof. The second external electrode layer 31 is electrically connected to the negative electrode layer 12, and the second metal layer 32 is electrically connected to the second external electrode layer 31.

[0031] The first metal layer 22 and the second metal layer 32 facilitate mounting the solid-state battery 1 on other components such as a circuit board. Further, the first metal layer 22 and the second metal layer 32 have relatively high moisture barrier properties. Therefore, the first metal layer 22 and the second metal layer 32 can each function as a protective layer for protecting the first external electrode layer 21 and the second external electrode layer 31 from external moisture.

[0032] Here, the configuration of the battery body 10 will be further described. The electrolyte layer 13 of the battery body 10 contains a solid electrolyte. For example, an oxide solid electrolyte is used for the solid electrolyte of the electrolyte layer 13. As the oxide solid electrolyte of the electrolyte layer 13, for example, LAGP, which is a type of NASICON (Na super ionic conductor) type (also referred to as "NASICON type") oxide solid electrolyte, is used. LAGP is an oxide solid electrolyte represented by the general formula Li 1+x Al x Ge 2-x (PO 4 ) 3 (0 < x ≤ 1). In addition, for the solid electrolyte of the electrolyte layer 13, a sulfide solid electrolyte such as Li 2 S (lithium sulfide)-P 2 S 5 (phosphorus pentasulfide) may be used.

[0033] The positive electrode layer 11 of the battery body 10 includes a positive electrode active material and a solid electrolyte. The solid electrolyte of the positive electrode layer 11 is an oxide solid electrolyte or a sulfide solid electrolyte, for example, the same type of material as the solid electrolyte used in the electrolyte layer 13. The positive electrode active material of the positive electrode layer 11 is, for example, Li 2 CoP 2 O 7 Lithium cobalt pyrophosphate (also referred to as "LCPO") or the like is used. The positive electrode layer 11 may further contain a conductive assistant in addition to the positive electrode active material and the solid electrolyte. The conductive assistant of the positive electrode layer 11 may be, for example, a carbon material such as carbon fiber, carbon black, graphite, graphene, or carbon nanotube, or a conductive material such as iron silicide.

[0034] The negative electrode layer 12 of the battery body 10 includes a negative electrode active material and a solid electrolyte. The solid electrolyte of the negative electrode layer 12 is an oxide solid electrolyte or a sulfide solid electrolyte, for example, the same type of material as the solid electrolyte used in the electrolyte layer 13. The negative electrode active material of the negative electrode layer 12 is, for example, TiO 2 (Titanium oxide), Nb 2 O 5 In addition, the negative electrode active material of the negative electrode layer 12 may be Li 3 V 2 (PO 4 ) 3 (Lithium vanadium phosphate), Li 4 Ti 5 O 12 (lithium titanate) or the like may be used. The negative electrode layer 12 may further contain a conductive assistant in addition to the negative electrode active material and the solid electrolyte. The conductive assistant of the negative electrode layer 12 may be, for example, a carbon material such as carbon fiber, carbon black, graphite, graphene, or carbon nanotube, or a conductive material such as iron silicide.

[0035] Although not shown here, the positive electrode layer 11 and the negative electrode layer 12 may each be provided with a current collector layer so as to be in contact with each other. In addition, such a current collector layer may contain a conductive assistant. When the current collector layer contains a conductive assistant, the positive electrode layer 11 and the negative electrode layer 12 may be configured to contain or not contain a conductive assistant.

[0036] When the solid-state battery 1 is charged, lithium ions are conducted from the positive electrode layer 11 through the electrolyte layer 13 to the negative electrode layer 12 and are incorporated therein, and when the solid-state battery 1 is discharged, lithium ions are conducted from the negative electrode layer 12 to the positive electrode layer 11 through the electrolyte layer 13 and are incorporated therein. In the solid-state battery 1, charging and discharging operations are realized by such lithium ion conduction caused by predetermined current application to the positive electrode terminal 20 and the negative electrode terminal 30 connected to the positive electrode layer 11 and the negative electrode layer 12, respectively.

[0037] For the insulating layer 15 of the battery body 10, various insulating materials having insulating properties are used. The insulating properties of the insulating material used for the insulating layer 15 refer to a property that has no or sufficiently low influence on the lithium ion conduction and electronic conduction in the laminate 14 including the positive electrode layer 11, the negative electrode layer 12, and the electrolyte layer 13. For example, for the insulating layer 15, an insulating material having a lower electronic conductivity than the positive electrode layer 11 and the negative electrode layer 12 is used. For the insulating layer 15, a material having low moisture and gas permeability and good sealing properties is preferably used. Among them, it is preferable to use for the insulating layer 15 a material having a linear expansion coefficient similar to that of each layer constituting the laminate 14 of the battery body 10, or a material having good adhesion to each layer. For the insulating material of the insulating layer 15, glass, ceramics, solid electrolytes, etc. are used.

[0038] The positive electrode layer 11 and the negative electrode layer 12 of the battery body 10 are also referred to as "electrode layers" or "internal electrode layers." The insulating layer 15 of the battery body 10 is also referred to as a "cover layer." Of the insulating layer 15, a portion adjacent to the side of the electrolyte layer 13, a portion adjacent to the side of the positive electrode layer 11, and a portion adjacent to the side of the negative electrode layer 12 are also referred to as "embedded layers."

[0039] The positive electrode terminal 20 and the negative electrode terminal 30 included in the solid-state battery 1 having the above-mentioned configuration will be further described. The first external electrode layer 21 of the positive electrode terminal 20 is provided so as to extend from the first end face 10a of the battery body 10 to a part of the outer surface 10c (the surface of the insulating layer 15) continuous with the first end face 10a of the battery body 10. The first external electrode layer 21 is electrically connected to the positive electrode layer 11 exposed at the first end face 10a. The first metal layer 22 is provided so as to cover the first external electrode layer 21 and is electrically connected to the first external electrode layer 21.

[0040] The first external electrode layer 21 has a first surface portion 21a on the first metal layer 22 side. The first surface portion 21a contains Cu as the entire conductive material or as the main body. The first external electrode layer 21 further has a first internal portion 21b between the first surface portion 21a and the battery body 10. For example, the first internal portion 21b contains Ag as the entire conductive material or as the main body. Alternatively, the first internal portion 21b may contain Cu as the entire conductive material or as the main body, or may be configured using the same type of conductive material as the first surface portion 21a. The first internal portion 21b is a portion provided so as to cover a part of the first end face 10a and the outer surface 10c of the battery body 10, and is a portion electrically connected to the positive electrode layer 11 exposed to the first end face 10a. The first surface portion 21a is a portion provided so as to cover the surface of the first internal portion 21b, and is a portion electrically connected to the first internal portion 21b. It is desirable that the first surface layer portion 21a covers the surface of the first inner layer portion 21b so that the first inner layer portion 21b is not exposed from the first surface layer portion 21a.

[0041] The first external electrode layer 21 is formed, for example, as follows. First, a paste containing Ag or Cu as the entire conductive material or mainly Ag or Cu is applied to the first end face 10a and part of the outer face 10c of the battery body 10, and the paste is cured or baked by a predetermined heat treatment to form the first internal layer portion 21b. Next, a paste containing Cu as the entire conductive material or mainly Cu is applied to the surface of the first internal layer portion 21b, and the paste is cured or baked by a predetermined heat treatment to form the first surface layer portion 21a. This forms the first external electrode layer 21 having the first internal layer portion 21b and the first surface layer portion 21a provided thereon. When the first surface layer portion 21a and the first inner layer portion 21b are both of the same type containing Cu as the entire or main conductive material, the first external electrode layer 21 may be formed by applying a paste containing Cu as the entire or main conductive material to the first end face 10a and a part of the outer face 10c of the battery body 10 once and subjecting it to a heat treatment (curing or baking). In this case, of the formed layer, the part on the battery body 10 side can be referred to as the first inner layer portion 21b, and the part on the surface side can be referred to as the first surface layer portion 21a.

[0042] The second external electrode layer 31 of the negative electrode terminal 30 is provided so as to extend from the second end face 10b of the battery body 10 to a part of the outer surface 10c continuous with the second end face 10b of the battery body 10. The second external electrode layer 31 is electrically connected to the negative electrode layer 12 exposed from the second end face 10b. The second metal layer 32 is provided so as to cover the second external electrode layer 31 and is electrically connected to the second external electrode layer 31.

[0043] The second external electrode layer 31 contains Ag as the entire conductive material or as the main component. The second external electrode layer 31 is formed by applying a paste containing Ag as the entire conductive material or as the main component to the second end face 10b and a part of the outer face 10c of the battery body 10, and curing or baking the paste by a predetermined heat treatment. The surface layer part on the second metal layer 32 side of the second external electrode layer 31 is also referred to as the "second surface layer part", and the part between the surface layer part (second surface layer part) and the battery body 10 is also referred to as the "second inner layer part". In this case, the second inner layer part is a part provided so as to cover a part of the second end face 10b and the outer face 10c of the battery body 10, and is electrically connected to the negative electrode layer 12 exposed at the second end face 10b. The second surface layer part is a part provided so as to cover the second inner layer part, and is electrically connected to the second inner layer part.

[0044] Regarding the solid-state battery 1, as an example, a case will be described in which the first inner layer portion 21b of the first external electrode layer 21 contains Ag as the entire or main conductive material. In this case, the paste used to form the first inner layer portion 21b of the first external electrode layer 21 and the second external electrode layer 31 (second surface layer portion and second inner layer portion) may be, for example, a paste containing Ag, which is the entire or main conductive material, and further organic components such as glass and resin. Such a paste is applied to a predetermined end of the battery body 10 and subjected to a predetermined heat treatment, whereby the organic components such as resin are removed and a composite of Ag and glass is baked onto the predetermined end of the battery body 10, thereby forming the first inner layer portion 21b of the first external electrode layer 21 or the second external electrode layer 31.

[0045] Alternatively, the paste used to form the first inner layer portion 21b of the first external electrode layer 21 and the second external electrode layer 31 (second surface layer portion and second inner layer portion) may be a paste containing, for example, Ag, which is the entire or main conductive material, and further an organic component such as a thermosetting resin. Such a paste is applied to a predetermined end of the battery body 10 and subjected to a predetermined heat treatment, whereby the thermosetting resin is hardened and a composite of Ag and the thermosetting resin is formed as the first inner layer portion 21b of the first external electrode layer 21 or the second external electrode layer 31.

[0046] The above-mentioned paste containing Ag is also referred to as "Ag-containing paste", and the layer formed by hardening or baking the Ag-containing paste, in this example, the first inner layer portion 21b of the first external electrode layer 21 and the second external electrode layer 31 (second surface layer portion and second inner layer portion), are also referred to as the "Ag-containing layer".

[0047] The paste used to form the first surface portion 21a of the first external electrode layer 21 may be, for example, a paste containing Cu, which is the entire or main conductive material, and further an organic component such as a thermosetting resin. Such a paste is applied to a predetermined end of the battery body 10 and subjected to a predetermined heat treatment, whereby the thermosetting resin is hardened and a composite of Cu and the thermosetting resin is formed as the first surface portion 21a of the first external electrode layer 21.

[0048] Alternatively, the paste used to form the first surface portion 21a of the first external electrode layer 21 may be a paste containing, for example, Cu, which is the entire or main conductive material, and further organic components such as glass and resin. Such a paste is applied to a predetermined end of the battery body 10 and subjected to a predetermined heat treatment, whereby the organic components such as resin are removed and a composite of Cu and glass is baked onto the predetermined end of the battery body 10, forming the first surface portion 21a of the first external electrode layer 21.

[0049] The above-mentioned paste containing Cu is also referred to as a "Cu-containing paste", and the layer formed by hardening or baking the Cu-containing paste, in this example, the first surface layer portion 21a of the first external electrode layer 21, is also referred to as a "Cu-containing layer".

[0050] As described above, in one example of the solid-state battery 1, in the first external electrode layer 21 of the positive electrode terminal 20, Ag is used as the conductive material of the first inner layer portion 21b, and Cu is used as the conductive material of the first surface layer portion 21a. In the solid-state battery 1, the first inner layer portion 21b using Ag is covered by the first surface layer portion 21a using Cu, which is less susceptible to migration than Ag. As a result, in the solid-state battery 1, the occurrence of Ag migration on the positive electrode terminal 20 side is suppressed during charging and discharging operations realized by passing a predetermined current through the positive electrode terminal 20 and the negative electrode terminal 30. That is, in the solid-state battery 1, the occurrence of migration 200 as shown in FIG. 1(A) and FIG. 1(B) is suppressed.

[0051] In addition, in the solid-state battery 1, Ag is used as the conductive material of the second external electrode layer 31 of the negative electrode terminal 30, in other words, the conductive material of the surface layer portion (second surface layer portion) and the inner layer portion (second inner layer portion) of the second external electrode layer 31, and the use of Cu in the second external electrode layer 31 is suppressed. As a result, in the solid-state battery 1, discoloration (or deterioration) of the second metal layer 32 or further the second external electrode layer 31 on the negative electrode terminal 30 side is suppressed during charging and discharging operations realized by passing a predetermined current through the positive electrode terminal 20 and the negative electrode terminal 30. That is, in the solid-state battery 1, discoloration 210 as shown in Figs. 2(A) and 2(B) is suppressed.

[0052] In this manner, in the solid-state battery 1, the occurrence of migration on the positive electrode terminal 20 side and the occurrence of discoloration on the negative electrode terminal 30 side during charging and discharging (energization) are both suppressed. By employing the above-described configuration for the first external electrode layer 21 of the positive electrode terminal 20 and the second external electrode layer 31 of the negative electrode terminal 30, a high-quality solid-state battery 1 is realized.

[0053] Here, the case where the first inner layer portion 21b of the first external electrode layer 21 contains Ag as all or mainly as its conductive material is taken as an example, but even if the first inner layer portion 21b contains Cu as all or mainly as its conductive material, a high-quality solid-state battery 1 is realized. In this case, a Cu-containing paste is used to form the first inner layer portion 21b (and the first surface layer portion 21a) of the first external electrode layer 21, and the first inner layer portion 21b (and the first surface layer portion 21a) is formed as a Cu-containing layer. By using Cu, which is less likely to cause migration than Ag, for the first inner layer portion 21b (and the first surface layer portion 21a) of the first external electrode layer 21, the occurrence of migration on the positive electrode terminal 20 side is suppressed. As for the negative electrode terminal 30 side, as described above, Ag is used for the second external electrode layer 31, and the use of Cu is suppressed, so that discoloration is suppressed. This realizes a high-quality solid-state battery 1.

[0054] The first external electrode layer 21 on the positive terminal 20 side may have a single-layer structure mainly made of Cu, instead of a two-layer structure with a first inner layer portion and a first surface layer portion. The second external electrode layer 31 on the negative terminal 30 side may have a single-layer structure mainly made of Ag, instead of a two-layer structure with a second inner layer portion and a second surface layer portion. As long as Cu is formed on the exterior surface on the positive terminal 20 side and Ag is formed on the exterior surface on the negative terminal 30 side, the above-mentioned effects can be obtained even with a single-layer structure.

[0055] It should be noted that the layer structures of the first external electrode layer 21 and the second external electrode layer 31 are not limited to those shown in FIG. 3(B) above. Fig. 4 is a diagram for explaining a second example of the solid-state battery according to the embodiment. Fig. 4 is a schematic cross-sectional view of a main part of the second example of the solid-state battery according to the embodiment. Fig. 4 is another example of a schematic cross-sectional view taken along line L3 in Fig. 3(A).

[0056] The solid-state battery 1A shown in FIG. 4 is an example of a solid-state battery in which the first external electrode layer 21 of the positive electrode terminal 20 and the second external electrode layer 31 of the negative electrode terminal 30 have a layer structure different from that described for the solid-state battery 1 (FIG. 3(B)).

[0057] The first external electrode layer 21 of the positive electrode terminal 20 of the solid-state battery 1A has a first surface layer portion 21a located on the first metal layer 22 side, and a first inner layer portion 21b located between the first surface layer portion 21a and the battery body 10 and having a two-layer structure. The first inner layer portion 21b has a two-layer structure including a first layer 21ba on the battery body 10 side and a second layer 21bb covering the first layer 21ba. By having the first inner layer portion 21b have such a two-layer structure of the first layer 21ba and the second layer 21bb, the moisture resistance of the battery body 10 is improved.

[0058] Moreover, the second external electrode layer 31 of the negative electrode terminal 30 of the solid-state battery 1A has a second surface layer portion 31a located on the second metal layer 32 side, and a second inner layer portion 31b located between the second surface layer portion 31a and the battery body 10, and has a two-layer structure of the second surface layer portion 31a and the second inner layer portion 31b. By having the second external electrode layer 31 have such a two-layer structure of the second inner layer portion 31b and the second surface layer portion 31a, the moisture resistance of the battery body 10 is improved.

[0059] On the positive electrode terminal 20 side of the solid-state battery 1A, the first surface layer portion 21a of the first external electrode layer 21 uses Cu as the entire or main conductive material. In the first internal layer portion 21b of the first external electrode layer 21, for example, Ag is used as the entire or main conductive material in both the first layer 21ba and the second layer 21bb. Alternatively, in the first internal layer portion 21b, Cu may be used as the entire or main conductive material in both the first layer 21ba and the second layer 21bb. Alternatively, in the first internal layer portion 21b, Ag may be used as the entire or main conductive material in one of the first layer 21ba and the second layer 21bb, and Cu may be used as the entire or main conductive material in the other.

[0060] The first external electrode layer 21 of the solid-state battery 1A is formed, for example, as follows. First, a paste containing Ag or Cu as the entire conductive material or mainly therein is applied to the first end face 10a and a part of the outer face 10c of the battery body 10, and the paste is cured or baked by a predetermined heat treatment to form the first layer 21ba of the first inner layer portion 21b. Next, a paste containing Ag or Cu as the entire conductive material or mainly therein is applied to the surface of the first layer 21ba, and the paste is cured or baked by a predetermined heat treatment to form the second layer 21bb of the first inner layer portion 21b. This forms the first inner layer portion 21b of a two-layer structure having the first layer 21ba and the second layer 21bb. Then, a paste containing Cu as the entire conductive material or mainly therein is applied to the surface of the first inner layer portion 21b (the second layer 21bb), and the paste is cured or baked by a predetermined heat treatment to form the first surface layer portion 21a. As a result, the first external electrode layer 21 having a three-layer structure is formed, which has the first layer 21ba and second layer 21bb of the first inner layer portion 21b and the first surface layer portion 21a provided thereon.

[0061] On the surface of the first external electrode layer 21 thus formed, a first metal layer 22 is formed by plating so as to cover it. Moreover, on the negative electrode terminal 30 side of the solid-state battery 1A, the second surface layer portion 31a and the second inner layer portion 31b of the second external electrode layer 31 both contain Ag entirely or mainly as the conductive material.

[0062] The second external electrode layer 31 of the solid-state battery 1A is formed, for example, as follows. First, a paste containing Ag as the entire conductive material or as the main component is applied to the second end face 10b and a part of the outer face 10c of the battery body 10, and the paste is cured or baked by a predetermined heat treatment to form the second internal layer portion 31b. Next, a paste containing Ag as the entire conductive material or as the main component is applied to the surface of the second internal layer portion 31b, and the paste is cured or baked by a predetermined heat treatment to form the second external layer portion 31a. This forms the second external electrode layer 31 having a two-layer structure, which includes the second internal layer portion 31b and the second external layer portion 31a provided thereon.

[0063] A second metal layer 32 is formed by plating on the surface of the second external electrode layer 31 thus formed so as to cover it. The same effects as those of the solid-state battery 1 can be obtained by using a solid-state battery 1A having the configuration shown in FIG.

[0064] Regarding the solid state battery 1A, as an example, a case will be described in which the first layer 21ba and the second layer 21bb of the first inner layer portion 21b of the first external electrode layer 21 each contain Ag entirely or mainly as the conductive material.

[0065] 4, in the first external electrode layer 21 of the positive terminal 20, Ag is used as the conductive material for the first layer 21ba and the second layer 21bb of the first inner layer portion 21b, and Cu, which is less susceptible to migration than Ag, is used as the conductive material for the first surface layer portion 21a. This prevents Ag migration from occurring on the positive terminal 20 side during charging and discharging of the solid-state battery 1A.

[0066] In addition, in the solid-state battery 1A, Ag is used as the conductive material of the second surface layer portion 31a and the second inner layer portion 31b of the second external electrode layer 31 of the negative electrode terminal 30, and the use of Cu in the second surface layer portion 31a and the second inner layer portion 31b is suppressed. This suppresses discoloration (or deterioration) of the second metal layer 32 or further the second external electrode layer 31 on the negative electrode terminal 30 side during charging and discharging operations of the solid-state battery 1A.

[0067] By employing the configuration as shown in FIG. 4 for the first external electrode layer 21 of the positive electrode terminal 20 and the second external electrode layer 31 of the negative electrode terminal 30, a high-quality solid-state battery 1A is realized. Here, the first layer 21ba and the second layer 21bb of the first inner layer portion 21b of the first external electrode layer 21 contain Ag as the entire or main conductive material, but a high-quality solid-state battery 1A can be realized even when both or either of the first layer 21ba and the second layer 21bb contain Cu as the entire or main conductive material. That is, by using Cu, which is less likely to cause migration than Ag, for the first inner layer portion 21b of the first external electrode layer 21, the occurrence of migration on the positive electrode terminal 20 side is suppressed. As for the negative electrode terminal 30 side, by using Ag for the second external electrode layer 31 as described above, the occurrence of discoloration is suppressed. This realizes a high-quality solid-state battery 1A.

[0068] In the above description, the first surface layer portion 21a in the first external electrode layer 21 of the positive electrode terminal 20 contains Cu as the entire or main conductive material, but the first surface layer portion 21a may contain a relatively small amount of Ag. The first surface layer portion 21a may contain Ni, Au (gold), Pd, Pt, etc., which are less likely to cause migration than Ag, instead of or together with Cu, as the entire or main conductive material. Various materials having higher migration resistance than Ag can be used as the entire or main conductive material of the first surface layer portion 21a. The first inner layer portion 21b or the first layer 21ba and second layer 21bb may use various materials having higher migration resistance than Ag, in addition to Ag, as the entire or main conductive material of the first inner layer portion 21b or the first layer 21ba and second layer 21bb.

[0069] Examples and comparative examples will be described below. Example 1 On one end surface of a given battery body where a part of the internal positive electrode layer is exposed, an Ag-containing paste containing Ag, which is all or mainly the conductive material, and further glass and resin, was applied as the internal layer portion (first internal layer portion) of the external electrode layer (first external electrode layer) on the positive electrode side, and baked by heat treatment to form a first Ag-containing layer, and then a second Ag-containing layer was formed in the same manner using the Ag-containing paste. Then, on the surface of the two Ag-containing layers formed, a Cu-containing paste containing Cu, which is all or mainly the conductive material, and further thermosetting resin, was applied as the surface layer portion (first surface layer portion) of the external electrode layer on the positive electrode side, and hardened by heat treatment to form one Cu-containing layer. As a result, a three-layer structure positive electrode side external electrode layer was formed on one end surface of the battery body, which is connected to the internal positive electrode layer, contains two Ag-containing layers as the internal layer portion, and contains one Cu-containing layer as the surface layer portion.

[0070] On the other end surface of this battery body where a part of the internal negative electrode layer was exposed, an Ag-containing paste was applied as the internal layer portion (second internal layer portion) of the external electrode layer (second external electrode layer) on the negative electrode side, and baked by heat treatment to form a single Ag-containing layer. Then, on the surface of this Ag-containing layer, an Ag-containing paste was similarly applied as the external layer portion (second external layer portion) of the external electrode layer on the negative electrode side, and baked by heat treatment to form a single Ag-containing layer. As a result, a two-layer structure external electrode layer on the negative electrode side was formed on the other end surface of the battery body, which is connected to the internal negative electrode layer, includes one Ag-containing layer as the internal layer portion, and includes one Ag-containing layer as the external layer portion.

[0071] On the surfaces of the formed positive and negative external electrode layers, a Ni layer and a Sn layer were successively deposited by plating to form metal layers (a first metal layer and a second metal layer). In this way, a positive electrode terminal including a positive external electrode layer and a metal layer on its surface was formed on one end surface of the battery body, and a negative electrode terminal including a negative external electrode layer and a metal layer on its surface was formed on the other end surface of the battery body, to obtain a solid-state battery of Example 1. The solid-state battery of Example 1 corresponds to one having a configuration like that of the solid-state battery 1A shown in FIG.

[0072] Comparative Example 1 On one end surface of a given battery body where a part of the internal positive electrode layer is exposed, an Ag-containing paste is applied as an inner layer portion (first inner layer portion) of the external electrode layer (first external electrode layer) on the positive electrode side, and baked by heat treatment to form a first Ag-containing layer, and a second Ag-containing layer is formed in the same manner using the Ag-containing paste. Then, on the surface of the two Ag-containing layers formed, a Cu-containing paste is applied as a surface layer portion (first surface layer portion) of the external electrode layer on the positive electrode side, and hardened by heat treatment to form one Cu-containing layer. As a result, a three-layer structure positive electrode side external electrode layer is formed on one end surface of the battery body, which is connected to the internal positive electrode layer, includes two Ag-containing layers as the inner layer portion, and includes one Cu-containing layer as the surface layer portion.

[0073] Similarly, on the other end face of this battery body, where a portion of the internal negative electrode layer was exposed, a negative electrode-side external electrode layer (second external electrode layer) having a three-layer structure was formed, which was connected to the internal negative electrode layer and included two Ag-containing layers as an inner layer portion (second inner layer portion) and one Cu-containing layer as a surface layer portion (second surface layer portion).

[0074] On the surfaces of the formed positive and negative external electrode layers, a Ni layer and a Sn layer were successively deposited by plating to form metal layers (a first metal layer and a second metal layer). In this way, a positive electrode terminal including a positive external electrode layer and a metal layer on its surface was formed on one end surface of the battery body, and a negative electrode terminal including a negative external electrode layer and a metal layer on its surface was formed on the other end surface of the battery body, thereby obtaining a solid-state battery of Comparative Example 1.

[0075] Comparative Example 2 On one end surface of a given battery body where a part of the internal positive electrode layer is exposed, an Ag-containing paste is applied as an inner layer portion (first inner layer portion) of the external electrode layer on the positive electrode side (first external electrode layer) and baked by heat treatment to form a single Ag-containing layer. Then, on the surface of this Ag-containing layer, an Ag-containing paste is similarly applied as a surface layer portion (first surface layer portion) of the external electrode layer on the positive electrode side and baked by heat treatment to form a single Ag-containing layer. As a result, a two-layer structure positive electrode side external electrode layer was formed on one end surface of the battery body, which is connected to the internal positive electrode layer, includes one Ag-containing layer as an inner layer portion, and includes one Ag-containing layer as a surface layer portion.

[0076] On the other end surface of this battery body where a part of the internal negative electrode layer is exposed, an Ag-containing paste was applied and baked by heat treatment as the internal layer portion (second internal layer portion) of the external electrode layer (second external electrode layer) on the negative electrode side to form a first Ag-containing layer, and a second Ag-containing layer was formed in the same manner using the Ag-containing paste. Then, on the surface of the two Ag-containing layers formed, a Cu-containing paste was applied and hardened by heat treatment as the surface layer portion (second surface layer portion) of the external electrode layer on the negative electrode side to form one Cu-containing layer. As a result, a three-layer structure external electrode layer on the negative electrode side was formed on the other end surface of the battery body, which is connected to the internal negative electrode layer, includes two Ag-containing layers as the internal layer portion, and includes one Cu-containing layer as the surface layer portion.

[0077] On the surfaces of the formed positive and negative external electrode layers, a Ni layer and a Sn layer were successively deposited by plating to form metal layers (a first metal layer and a second metal layer). In this way, a positive electrode terminal including a positive external electrode layer and a metal layer on its surface was formed on one end surface of the battery body, and a negative electrode terminal including a negative external electrode layer and a metal layer on its surface was formed on the other end surface of the battery body, thereby obtaining a solid-state battery of Comparative Example 2.

[0078] Table 1 shows the configurations of the external electrode layers (the inner layer portions and surface layer portions) on the positive and negative electrode sides of the solid-state batteries of Example 1 and Comparative Example 1-2.

[0079] [Table 1]

[0080] 〔evaluation〕 A plurality of samples of the solid-state batteries of Example 1 and Comparative Example 1-2 were prepared, and 10 cycles of charge and discharge were performed in an environment of a temperature of 85°C and a relative humidity (RH) of 85% for each of the cases where the batteries were mounted with a conductive paste containing Ag and where the batteries were mounted by reflow. After 10 cycles of charge and discharge, the samples of the solid-state batteries of Example 1 and Comparative Example 1-2 were evaluated for the number of migration suppressions on the positive electrode terminal side and the presence or absence of discoloration on the negative electrode terminal side. The evaluation results are shown in Table 2.

[0081] [Table 2]

[0082] In the solid-state battery of Example 1, the surface layer of the external electrode layer on the positive electrode side contains Cu as the entire conductive material or as the main conductive material, and the surface layer of the external electrode layer on the negative electrode side contains Ag as the entire conductive material or as the main conductive material (Table 1). In the solid-state battery of Example 1 in which the surface layer of the external electrode layer on the positive electrode side contains Cu, as shown in Table 2, when mounted with a conductive paste, the occurrence of migration on the positive electrode terminal side was suppressed in two out of three samples, and when mounted by reflow, the occurrence of migration on the positive electrode terminal side was suppressed in three out of three samples. Furthermore, in the solid-state battery of Example 1 in which the surface layer of the external electrode layer on the negative electrode side contains Ag and the content of Cu was suppressed, discoloration on the negative electrode terminal side was not observed in either the case of mounting with a conductive paste or the case of mounting by reflow, as shown in Table 2.

[0083] In addition, in the solid-state battery of Comparative Example 1, Cu is contained as the entire conductive material or as the main component in the surface layer of both the positive and negative external electrode layers (Table 1). In the solid-state battery of Comparative Example 1 in which Cu is contained in the surface layer of the positive external electrode layer, as shown in Table 2, when mounted with conductive paste, the occurrence of migration on the positive terminal side was suppressed in three out of three samples, and when mounted by reflow, the occurrence of migration on the positive terminal side was suppressed in two out of three samples. However, unlike Example 1, in the solid-state battery of Comparative Example 1 in which Cu is contained in the surface layer of the negative external electrode layer, discoloration on the negative terminal side was observed in both cases of mounting with conductive paste and mounting by reflow, as shown in Table 2.

[0084] In addition, in the solid-state battery of Comparative Example 2, Ag is contained as the entire or main conductive material in the surface layer of the external electrode layer on the positive electrode side, and Cu is contained as the entire or main conductive material in the surface layer of the external electrode layer on the negative electrode side (Table 1). Unlike Example 1, in the solid-state battery of Comparative Example 2 in which Ag is contained in the surface layer of the external electrode layer on the positive electrode side, the occurrence of migration was not suppressed in all three samples in both cases of mounting with a conductive paste and mounting by reflow, as shown in Table 2. Furthermore, unlike Example 1, in the solid-state battery of Comparative Example 2 in which Cu is contained in the surface layer of the external electrode layer on the negative electrode side, discoloration was observed on the negative electrode terminal side in both cases of mounting with a conductive paste and mounting by reflow.

[0085] According to the solid-state battery employing the configuration of Example 1, that is, the configuration in which the surface layer of the external electrode layer on the positive electrode side contains Cu and the surface layer of the external electrode layer on the negative electrode side contains Ag, the occurrence of migration on the positive electrode side and the occurrence of discoloration on the negative electrode side during charging and discharging (current application) were both effectively suppressed. It was confirmed that the adoption of the configuration of Example 1 allows the realization of a high-quality solid-state battery. [Explanation of symbols]

[0086] 1, 1A, 100A, 100B solid state battery 10, 110 Battery body 10a, 110a 1st end surface 10b, 110b 2nd end surface 10c external surface 11, 111 Positive electrode layer 12, 112 negative electrode layer 13, 113 electrolyte layer 14, 114 Laminate 15, 115 Insulation layer 20, 120A, 120B positive terminal 21, 121A, 121B 1st external electrode layer 21a 1st surface layer 21b First Inner Layer 21ba 1st layer 21bb 2nd layer 22, 122A, 122B 1st metal layer 30, 130A, 130B negative terminal 31, 131A, 131B 2nd external electrode layer 31a 2nd surface layer 31b Second Inner Layer 32, 132A, 132B 2nd metal layer 200 Migration 210 Discoloration D1 1st direction D2 2nd direction D2a 1st side D2b Second side

Claims

1. a battery main body including a laminate in which a positive electrode layer and a negative electrode layer are laminated with an electrolyte layer interposed therebetween in a first direction, and an insulating layer covering the laminate, the battery main body having a first end surface facing a first side in a second direction perpendicular to the first direction and where a part of the positive electrode layer is exposed from the insulating layer, and a second end surface facing a second side opposite to the first side in the second direction, and where a part of the negative electrode layer is exposed from the insulating layer; a first external electrode layer covering the first end surface and connected to the positive electrode layer; a second external electrode layer covering the second end surface and connected to the negative electrode layer; a first metal layer covering the first external electrode layer; a second metal layer covering the second external electrode layer; Including, the first external electrode layer contains Cu in a first surface layer portion on the first metal layer side, the second external electrode layer contains Ag in a second surface layer portion on the second metal layer side.

2. the first external electrode layer has a first inner layer portion containing Ag or Cu between the first surface layer portion and the battery body, The solid-state battery according to claim 1 , wherein the second external electrode layer has a second internal layer portion containing Ag between the second surface layer portion and the battery body.

3. The solid-state battery according to claim 2 , wherein the first inner layer portion has a laminated structure of at least two layers.

4. The solid-state battery according to claim 1 , wherein the first surface layer further contains a resin.

5. forming a battery body having a laminate in which a positive electrode layer and a negative electrode layer are laminated in a first direction with an electrolyte layer interposed therebetween, and an insulating layer covering the laminate, the battery body having a first end surface facing a first side in a second direction perpendicular to the first direction and where a part of the positive electrode layer is exposed from the insulating layer, and a second end surface facing a second side opposite to the first side in the second direction and where a part of the negative electrode layer is exposed from the insulating layer; forming a first external electrode layer covering the first end surface and connected to the positive electrode layer; forming a second external electrode layer covering the second end surface and connected to the negative electrode layer; forming a first metal layer covering the first external electrode layer; forming a second metal layer covering the second external electrode layer; Including, the step of forming the first external electrode layer includes a step of forming the first external electrode layer containing Cu on a first surface layer portion on the first metal layer side, The method for manufacturing a solid-state battery, wherein the step of forming the second external electrode layer includes a step of forming the second external electrode layer containing Ag in a second surface layer portion on the second metal layer side.

6. the step of forming the first external electrode layer includes a step of forming a first internal layer portion containing Ag or Cu between the first surface layer portion and the battery body, 6. The method for producing a solid-state battery according to claim 5, wherein the step of forming the second external electrode layer includes a step of forming a second internal layer portion containing Ag between the second surface layer portion and the battery body.

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