All-solid-state secondary battery, laminated all-solid-state secondary battery

Abstract

To provide an all-solid secondary battery and a laminated all-solid secondary battery in which a crack is suppressed in a current collector more than before or the current collector is cut less easily while the unevenness of a surface of the all-solid secondary battery is reduced, and further which are easy to manufacture.SOLUTION: There is provided an all-solid secondary battery which includes: a positive electrode layer; a negative electrode layer; a solid electrolyte layer stacked between the positive electrode layer and the negative electrode layer; an insulating layer disposed on a side end surface of the positive electrode layer to cover the positive electrode layer; a foil-shaped positive electrode current collector part projecting from the positive electrode layer toward a side; and a foil-shaped negative electrode current collector part projecting from the negative electrode layer toward a side. The insulating layer supports the positive electrode current collector part and the negative electrode current collector part from at least one side of these current collector parts. The insulating layer is provided with two conductive parts which electrically connect the positive electrode current collector part and the negative electrode current collector part to outside wiring, respectively, and the two conductive parts are formed to penetrate through the insulating layer in a stacking direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an all-solid-state secondary battery and a laminated all-solid-state secondary battery. [Background technology]

[0002] In order to improve the energy density of all-solid-state secondary batteries and to realize high-capacity battery packs, it is necessary to use a plurality of all-solid-state secondary batteries stacked together. When a plurality of all-solid-state secondary batteries are stacked and used in this way, in order to improve rate characteristics and cycle characteristics by suppressing short circuits, it is preferable that each all-solid-state secondary battery (also referred to as a single cell) has two solid electrolyte layers stacked on both sides of a positive electrode layer, and that the two solid electrolyte layers are sandwiched between two negative electrode layers from the outside, thereby reducing the surface irregularities of the negative electrode layer, which is the outermost layer, and reducing the physical influence on adjacent all-solid-state secondary batteries.

[0003] Therefore, in Patent Document 1, a stack for forming a single cell having the above-described configuration is placed on a support plate, laminated, and packed, and pressure is applied from the stacking direction by an isostatic press, thereby producing an all-solid-state secondary battery with further reduced surface irregularities. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-121558 Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, the inventors have noticed that in all-solid-state secondary batteries manufactured by applying pressure from the stacking direction using isostatic pressing, there may be a problem in which the charge / discharge capacity cannot be exhibited as designed. As a result of careful investigation by the inventors, it became clear that the cause of this defect was a crack in part of the current collecting portion, which is a foil-like protruding portion provided to electrically connect the positive electrode layer to external wiring, or that the current collecting portion was cut.

[0006] Therefore, in order to further reduce the probability of cracks or breakage occurring in the current collecting portion, the inventors came up with the idea of ​​covering the current collecting portion on both sides with an insulating protective member when performing isostatic pressing. However, according to this manufacturing method, it is necessary to remove the protective member after the isostatic pressing in order to electrically connect the current collector to an external wiring. This step is significantly simpler than, for example, reconnecting the cut current collector to the positive electrode layer. However, it is inevitable that a new process will be added to the manufacturing process of all-solid-state secondary batteries. Furthermore, when manufacturing a stacked all-solid-state secondary battery by stacking a plurality of all-solid-state secondary batteries (single cells) each having the above-described protective member, it is necessary to stack a plurality of these single cells after removing the protective member. Therefore, each single cell must be isostatically pressed one by one. Furthermore, the removal of the protective member causes gaps between the unit cells, which increases the possibility that cracks will occur in part of the current collecting portion or that the current collecting portion will be cut when the stacked all-solid-state secondary battery is laminate-packed. If multiple single cell laminates before isostatic pressing are stacked and then isostatically pressed at the same time, the protective member will be fixed in place by being sandwiched between the current collecting parts of the multiple single cells. As a result, there is a problem that it becomes difficult to remove the protective member.

[0007] The present invention has been made in view of the above problems, and has an object to provide an all-solid-state secondary battery and a laminated all-solid-state secondary battery that are easier to manufacture and that are less likely to cause cracks or break than conventional current collecting parts while reducing surface irregularities. [Means for solving the problem]

[0008] That is, the all-solid-state secondary battery according to the present invention includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer stacked between the positive electrode layer and the negative electrode layer. This all-solid-state secondary battery further includes an insulating layer arranged on a side end surface of the positive electrode layer so as to cover the positive electrode layer, a foil-shaped positive electrode current collector protruding laterally from the positive electrode layer, and a foil-shaped negative electrode current collector protruding laterally from the negative electrode layer, and the insulating layer is configured to support the positive electrode current collector and the negative electrode current collector from at least one side thereof. The insulating layer is provided with two conductive portions that electrically connect the positive electrode current collector and the negative electrode current collector to external wiring, respectively, and the two conductive portions are formed to penetrate the insulating layer in the stacking direction.

[0009] With this all-solid-state secondary battery, isostatic pressure can be applied to the positive electrode current collector and the negative electrode current collector while they are supported by the insulating layer on at least one side. As a result, the insulating layer functions as a protective member to protect the current collectors, preventing cracks from occurring in the positive electrode current collector and / or the negative electrode current collector or cutting of the positive electrode current collector and / or the negative electrode current collector when pressure is applied. Furthermore, conductive portions that connect the positive electrode current collector and the negative electrode current collector to external wiring are provided so as to penetrate the insulating layer, so the insulating layer does not get in the way when using the all-solid-state secondary battery or when stacking all-solid-state secondary batteries to manufacture a stacked all-solid-state secondary battery. This eliminates the need to remove the portion of the insulating layer that supports the positive electrode current collector or the negative electrode current collector.

[0010] A specific embodiment of the present invention is one in which the two conductive portions are arranged in positions where they are not electrically connected to each other.

[0011] The solid electrolyte layers may be laminated on both sides of the positive electrode layer, the negative electrode layers may be laminated on the surfaces of the solid electrolyte layers opposite to the positive electrode layers, and the insulating layers may sandwich the positive electrode current collecting portion from the stacking direction of the layers.

[0012] The conductive portion has an electrical conductivity of 10 6 It is preferable that the material be S / m or higher.

[0013] More specific examples include those in which the conductive portion is a composite containing one or more substances selected from the group consisting of metals, alloys, metal powders, carbon materials, and electronically conductive polymers, or a composite containing any of these substances and a resin.

[0014] As a specific embodiment, it is preferable that the insulating layer is made of a resin or contains a resin.

[0015] If the insulating layer further contains an insulating filler, the insulating filler can improve the adhesion between the materials forming the insulating layer, thereby improving the strength of the insulating layer.

[0016] The insulating filler may be one or more substances selected from the group consisting of fibrous resin, resin nonwoven fabric, alumina, magnesium oxide, silica, boehmite, barium titanate, barium carbonate, yttria, manganese oxide, and the like.

[0017] It is preferable to position part or all of the outer edge of the insulating layer on the side where the current collecting portion protrudes outside the outer edge of the second electrode layer, as this can prevent short circuits due to physical contact between the positive electrode layer and the negative electrode layer.

[0018] In order to further prevent short circuits between the positive electrode layer and the negative electrode layer, it is preferable that a part or all of the outer edge of the negative electrode layer is disposed on the insulating layer.

[0019] It is preferable that the solid electrolyte layer of the all-solid-state secondary battery contains a sulfide-based solid electrolyte containing at least lithium, phosphorus, and sulfur, since this can further improve the battery performance.

[0020] It is preferable that the anode layer contains an anode active material that forms an alloy with lithium and / or an anode active material that forms a compound with lithium, that metallic lithium can be deposited inside the anode layer during charging, and that 80% or more of the charge capacity of the anode layer is exhibited by metallic lithium.

[0021] In a specific embodiment of the present invention, the negative electrode layer may include one or more selected from the group consisting of amorphous carbon, gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, and zinc. [Effects of the Invention]

[0022] According to the present invention, the method for producing an all-solid-state battery includes a uniform pressurizing step, so that unevenness on the surface of the all-solid-state secondary battery can be flattened. Furthermore, since the positive electrode current collecting portion and the negative electrode current collecting portion are protected from at least one side by an insulating layer while pressure is being applied, the probability of cracks occurring at the base of the positive electrode current collecting portion and the negative electrode current collecting portion or of the positive electrode current collecting portion and the negative electrode current collecting portion being cut can be further reduced compared to conventional methods.

[0023] Furthermore, two conductive parts that electrically connect the positive electrode current collecting part and the negative electrode current collecting part to external wiring, respectively, are formed so as to penetrate the insulating layer. Therefore, it is possible to use the all-solid-state secondary battery as it is without taking the trouble of removing the insulating layer after pressure molding, or to manufacture a laminated all-solid-state secondary battery by stacking the battery as it is. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a cross-sectional view showing a schematic configuration of an all-solid-state secondary battery according to one embodiment of the present invention. [Figure 2] FIG. 1 is an enlarged cross-sectional view showing a schematic configuration of an all-solid-state secondary battery according to an embodiment of the present invention. [Figure 3] FIG. 1 is an enlarged plan view showing a schematic configuration of an all-solid-state secondary battery according to an embodiment of the present invention. [Figure 4] 1A to 1C are schematic diagrams illustrating a method for manufacturing an all-solid-state secondary battery according to an embodiment of the present invention. [Figure 5] 5(a) and 5(b) are schematic diagrams showing the structure of an insulating layer material (gasket after embedding conductive member) used in the all-solid-state secondary battery according to the present embodiment, where Fig. 5(a) is a plan view and Fig. 5(b) is a cross-sectional view. [Figure 6] 6(a) and 6(b) are schematic diagrams showing the structure of a gasket before embedding a conductive member used in an all-solid-state secondary battery according to an embodiment of the present invention, where Fig. 6(a) is a plan view and Fig. 6(b) is a cross-sectional view. [Figure 7] 1A to 1C are schematic diagrams illustrating a method for manufacturing an all-solid-state secondary battery according to an embodiment of the present invention. [Figure 8] 1A to 1C are schematic diagrams illustrating a method for manufacturing an all-solid-state secondary battery according to an embodiment of the present invention. [Figure 9] FIG. 2 is a view of the positive electrode layer and the insulating layer of the all-solid-state secondary battery according to the embodiment, viewed from the stacking direction. [Figure 10] FIG. 2 is a cross-sectional view showing a schematic configuration of an all-solid-state secondary battery according to another embodiment of the present invention. [Figure 11] 1 is a graph showing evaluation results of all-solid-state secondary batteries according to examples of the present invention. [Figure 12] 1 is a graph showing evaluation results of all-solid-state secondary batteries according to examples of the present invention. [Figure 13] 1 is a graph showing evaluation results of all-solid-state secondary batteries according to examples of the present invention. [Figure 14] 1 is a graph showing evaluation results of all-solid-state secondary batteries according to examples of the present invention. [Figure 15] 10 is a graph showing evaluation results of all-solid-state secondary batteries according to comparative examples of the present invention. [Figure 16] 10 is a graph showing evaluation results of all-solid-state secondary batteries according to comparative examples of the present invention. [Figure 17] 10 is a graph showing evaluation results of all-solid-state secondary batteries according to comparative examples of the present invention. [Figure 18] 10 is a graph showing evaluation results of all-solid-state secondary batteries according to comparative examples of the present invention. [Figure 19] 10 is a graph showing evaluation results of all-solid-state secondary batteries according to comparative examples of the present invention. [Figure 20] 10 is a graph showing evaluation results of all-solid-state secondary batteries according to comparative examples of the present invention. [Figure 21] 10 is a graph showing evaluation results of all-solid-state secondary batteries according to comparative examples of the present invention. [Figure 22] 10 is a graph showing evaluation results of all-solid-state secondary batteries according to comparative examples of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0025] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In this specification and the drawings, components having substantially the same functional configurations are designated by the same reference numerals, and redundant description will be omitted. Furthermore, the components in the drawings have been enlarged or reduced as appropriate for ease of explanation, and the size and proportions of the components in the drawings may differ from those in reality.

[0026] <1. Structure of all-solid-state secondary battery> First, the configuration of an all-solid-state secondary battery 1 according to an embodiment of the present invention will be described. The all-solid-state secondary battery 1 according to this embodiment includes a positive electrode layer 10, a negative electrode layer 20, and a solid electrolyte layer 30. More specifically, this is an all-solid-state lithium secondary battery including one of the positive electrode layer 10 and the negative electrode layer 20 (hereinafter also referred to as a first electrode layer), solid electrolyte layers 30 stacked on both sides of the first electrode layer, the other of the positive electrode layer 10 and the negative electrode layer 20 (hereinafter also referred to as a second electrode layer) stacked on the surface of each solid electrolyte layer opposite the first electrode layer, and an insulating layer 13 disposed on a side end surface S of the first electrode layer. In this embodiment, as shown in FIGS. 1 and 2 , a battery in which the first electrode layer is the positive electrode layer 10 and the second electrode layer is the negative electrode layer 20 will be described. Note that the side end surface refers to the peripheral end not in the stacking direction of the layers, but rather the end of each layer in a direction perpendicular to the stacking direction of the layers.

[0027] (1-1. Positive electrode layer) As shown in FIG. 2, the positive electrode layer 10 includes a positive electrode current collector 11 and a positive electrode active material layer 12. Examples of the positive electrode current collector 11 include a plate or foil made of stainless steel, titanium (Ti), nickel (Ni), aluminum (Al), or an alloy thereof. The thickness of the positive electrode current collector 11 is, for example, 1 μm or more and 50 μm or less, more preferably 5 μm or more and 30 μm or less. 2, the positive electrode active material layers 12 are disposed on both sides of the positive electrode current collector 11. The positive electrode active material layers 12 contain at least a positive electrode active material and a solid electrolyte. The solid electrolyte contained in the positive electrode active material layer 12 may or may not be the same type as the solid electrolyte contained in the solid electrolyte layer 30. Details of the solid electrolyte will be described later in the section on the solid electrolyte layer 30.

[0028] The positive electrode active material may be any positive electrode active material that can reversibly store and release lithium ions.

[0029] For example, the positive electrode active material may be in the form of powder or granules, and can be formed using lithium salts such as lithium cobalt oxide (hereinafter referred to as LCO), lithium nickel oxide, lithium nickel cobalt oxide, lithium nickel cobalt aluminum oxide (hereinafter referred to as NCA), lithium nickel cobalt manganate (hereinafter referred to as NCM), lithium manganate, lithium iron phosphate, etc., nickel sulfide, copper sulfide, sulfur, iron oxide, or vanadium oxide. These positive electrode active materials may be used alone or in combination of two or more kinds.

[0030] In addition, the positive electrode active material preferably contains a lithium salt of a transition metal oxide having a layered rock salt structure among the above-mentioned lithium salts. Here, "layered" represents a thin sheet-like shape. Also, "rock salt structure" refers to a sodium chloride-type structure which is a kind of crystal structure, specifically, a structure in which the face-centered cubic lattices formed by each of the cations and anions are displaced from each other by 1 / 2 of the edge of the unit lattice.

[0031] Examples of the lithium salt of the transition metal oxide having such a layered rock salt structure include lithium salts of ternary transition metal oxides such as LiNi x Co y Al z O2 (NCA), or LiNi x Co y Mn z O2 (NCM) (where 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z = 1).

[0032] When the positive electrode active material contains a lithium salt of a ternary transition metal oxide having the above-mentioned layered rock salt structure, the energy density and thermal stability of the all-solid-state secondary battery 1 can be improved.

[0033] The surface of the positive electrode active material may be covered with a coating layer. Here, the coating layer of this embodiment may be any known coating layer for a positive electrode active material of an all-solid-state secondary battery 1. Examples of the coating layer include Li2O-ZrO2.

[0034] Furthermore, when the positive electrode active material is formed of a lithium salt of a ternary transition metal oxide such as NCA or NCM and contains nickel (Ni) as the positive electrode active material, it is possible to increase the capacity density of the all-solid-state secondary battery 1 and reduce metal elution from the positive electrode active material in a charged state. This allows the all-solid-state secondary battery 1 according to this embodiment to have improved long-term reliability and cycle characteristics in a charged state.

[0035] Here, examples of the shape of the positive electrode active material include particle shapes such as spherical and oval spheres. The particle size of the positive electrode active material is not particularly limited, and may be within a range applicable to positive electrode active materials in conventional all-solid-state secondary batteries. The content of the positive electrode active material in the positive electrode layer 10 is also not particularly limited, and may be within a range applicable to the positive electrode layer 10 of conventional all-solid-state secondary batteries 1.

[0036] In addition to the above-described positive electrode active material and solid electrolyte, the positive electrode active material layer 12 may contain additives such as a conductive aid, a binder, a filler, a dispersant, an ion conductive aid, or the like, as appropriate.

[0037] Examples of conductive additives that can be blended into the positive electrode active material layer 12 include graphite, carbon black, acetylene black, ketjen black, carbon fiber, carbon nanotubes, graphene, and metal powder. Examples of binders that can be blended into the positive electrode active material layer 12 include styrene butadiene rubber (SBR), polytetrafluoroethylene, polyvinylidene fluoride, and polyethylene. Furthermore, known materials generally used for electrodes of the all-solid-state secondary battery 1 can be used as fillers, dispersants, ion-conducting additives, and the like that can be blended into the positive electrode active material layer 12.

[0038] The thickness of the positive electrode active material layer 12 in the completed battery is not particularly limited, but is preferably, for example, 20 μm or more and 1000 μm or less, more preferably 50 μm or more and 500 μm or less, and particularly preferably 100 μm or more and 300 μm or less.

[0039] (1-2. Negative electrode layer) The negative electrode layer 20 includes, for example, a plate-shaped or foil-shaped negative electrode current collector 21 and a negative electrode active material layer 22 formed on the negative electrode current collector 21, as shown in FIG. In this embodiment, the negative electrode current collector 21 forms the outermost layer of the all-solid-state secondary battery 1. The negative electrode current collector 21 is preferably made of a material that does not react with lithium, that is, that does not form any alloy or compound with lithium. In addition to stainless steel, examples of materials that can be used to form the negative electrode current collector 21 include copper (Cu), titanium (Ti), iron (Fe), cobalt (Co), and nickel (Ni). The negative electrode current collector 21 may be made of any one of these metals, or may be made of an alloy or clad material of two or more metals. The thickness of the negative electrode current collector 21 is, for example, 1 μm or more and 50 μm or less, and more preferably 5 μm or more and 30 μm or less.

[0040] The negative electrode active material layer 22 contains, for example, at least one of a negative electrode active material that forms an alloy with lithium and a negative electrode active material that forms a compound with lithium. The negative electrode active material layer 22 may be configured so that metallic lithium can be deposited on one or both surfaces of the negative electrode active material layer 22 by containing such a negative electrode active material, as described below.

[0041] Examples of the negative electrode active material include amorphous carbon, gold, platinum, palladium (Pd), silicon (Si), silver, aluminum (Al), bismuth (Bi), tin, antimony, and zinc. Examples of the amorphous carbon include carbon black such as acetylene black, furnace black, and ketjen black, and graphene.

[0042] The shape of the negative electrode active material is not particularly limited, and may be granular or may be a uniform layer such as a plating layer. In the former case, lithium ions or lithium pass through the interior of the granular negative electrode active material or the gaps between the negative electrode active materials, and a metal layer mainly composed of lithium is formed between the negative electrode active material layer 22 and the negative electrode current collector 21, and some of the lithium exists in the negative electrode active material layer 22 by forming an alloy with a metal element in the negative electrode active material, for example. On the other hand, in the latter case, the metal layer is deposited between the negative electrode active material layer 22 and the solid electrolyte layer 30 .

[0043] Among the above, the negative electrode active material layer 22 is made of amorphous carbon having a specific surface area of ​​100 m2 measured by nitrogen gas adsorption method. 2 / g or less, and a low-specific surface area amorphous carbon with a specific surface area of ​​300m as measured by the nitrogen gas adsorption method. 2 It is preferable that the carbon nanotube contains a mixture of amorphous carbon with a high specific surface area of ​​1 / g or more.

[0044] The negative electrode active material layer 22 may contain only one of these negative electrode active materials, or may contain two or more negative electrode active materials. For example, the negative electrode active material layer 22 may contain only amorphous carbon as the negative electrode active material, or may contain one or more selected from the group consisting of gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, antimony, and zinc. Alternatively, the negative electrode active material layer 22 may contain a mixture of amorphous carbon and one or more selected from the group consisting of gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, antimony, and zinc.

[0045] The mixing ratio (mass ratio) of the mixture of amorphous carbon and the above-mentioned metal such as gold is preferably about 1:1 to 1:3. By using these materials as the negative electrode active material, the characteristics of the all-solid-state secondary battery 1 are further improved.

[0046] When amorphous carbon and at least one selected from the group consisting of gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, antimony, and zinc are used as the negative electrode active material, the particle size of the negative electrode active material is preferably 4 μm or less, which further improves the characteristics of the all-solid-state secondary battery 1.

[0047] When the negative electrode active material is a material capable of forming an alloy with lithium, such as at least one selected from the group consisting of gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, antimony, and zinc, the negative electrode active material layer 22 may be a layer made of such a metal. For example, the metal layer may be a plating layer.

[0048] The negative electrode active material layer 22 may further contain a binder, if necessary. Examples of the binder include styrene butadiene rubber (SBR), polytetrafluoroethylene (PTFE), polyvinylidene fluoride, and polyethylene oxide. The binder may be composed of one or more of these. By including a binder in the negative electrode active material layer 22 in this manner, it is possible to suppress the separation of the negative electrode active material, particularly when the negative electrode active material is granular. The content of the binder contained in the negative electrode active material layer 22 is, for example, 0.3% by mass to 20.0% by mass, preferably 1.0% by mass to 15.0% by mass, and more preferably 3.0% by mass to 15.0% by mass, relative to the total mass of the negative electrode active material layer 22.

[0049] Furthermore, the negative electrode active material layer 22 may contain additives used in conventional all-solid-state secondary batteries 1, such as fillers, dispersants, and ion-conductive materials, as appropriate.

[0050] Although there are no particular limitations on the thickness of the negative electrode active material layer 22, when the negative electrode active material is granular, the thickness in the completed battery state is, for example, 1 μm to 30 μm, preferably 5 μm to 20 μm. By setting the thickness in this range, the resistance value of the negative electrode active material layer 22 can be sufficiently reduced while fully obtaining the above-mentioned effects of the negative electrode active material layer 22, and the characteristics of the all-solid-state secondary battery 1 can be sufficiently improved. On the other hand, when the negative electrode active material forms a uniform layer, the thickness of the negative electrode active material layer 22 is, for example, 1 nm or more and 100 nm or less. In this case, the upper limit of the thickness of the negative electrode active material layer 22 is preferably 95 nm, more preferably 90 nm, and even more preferably 50 nm.

[0051] The present invention is not limited to the above-described embodiment, and the negative electrode active material layer 22 may have any configuration that can be used as the negative electrode active material layer 22 of the all-solid-state secondary battery 1. For example, the negative electrode active material layer 22 may be a layer containing the above-mentioned negative electrode active material, a solid electrolyte, and a negative electrode layer conductive additive.

[0052] In this case, for example, a metal active material or a carbon active material can be used as the negative electrode active material. Examples of the metal active material include metals such as lithium (Li), indium (In), aluminum (Al), tin (Sn), and silicon (Si), as well as alloys thereof. Examples of the carbon active material include artificial graphite, graphite carbon fiber, resin-baked carbon, pyrolytic vapor-grown carbon, coke, mesocarbon microbeads (MCMB), furfuryl alcohol resin-baked carbon, polyacene, pitch-based carbon fiber, vapor-grown carbon fiber, natural graphite, and non-graphitizable carbon. These negative electrode active materials may be used alone or in combination of two or more.

[0053] The conductive additive for the negative electrode layer and the solid electrolyte can be the same compounds as the conductive agent and the solid electrolyte contained in the positive electrode active material layer 12. Therefore, a description of their configurations will be omitted here.

[0054] (1-3.Solid electrolyte layer) The solid electrolyte layer 30 is a layer formed between the positive electrode layer 10 and the negative electrode layer 20, and contains a solid electrolyte. In this embodiment, the solid electrolyte layer 30 is laminated between the positive electrode layer 10 and the negative electrode layer 20 . The thickness of the solid electrolyte layer 30 in the completed battery state may be 5 μm or more and 100 μm or less, preferably 8 μm or more and 80 μm or less, and more preferably 10 μm or more and 50 μm or less.

[0055] The solid electrolyte is, for example, in powder form, and is made of, for example, a sulfide-based solid electrolyte material. Examples of the sulfide-based solid electrolyte material include Li2S-P2S5, Li2S-P2S5-LiX (X is a halogen element, for example, I, Br, or Cl), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, and Li2 S -SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (m and n are positive numbers, Z is Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (p and q are positive numbers, and M is any of P, Si, Ge, B, Al, Ga, and In). Here, the sulfide-based solid electrolyte material is produced by treating a starting material (e.g., Li2S, P2S5, etc.) by a melt quenching method, a mechanical milling method, or the like. Furthermore, these treatments may be followed by a heat treatment. The solid electrolyte may be amorphous, crystalline, or a mixture of both.

[0056] Furthermore, among the above sulfide-based solid electrolyte materials, it is preferable to use a material containing sulfur and one or more elements selected from the group consisting of silicon, phosphorus, and boron as the solid electrolyte. This improves the lithium conductivity of the solid electrolyte layer 30 and improves the battery characteristics of the all-solid-state secondary battery 1. In particular, it is preferable to use a solid electrolyte containing at least sulfur (S), phosphorus (P), and lithium (Li) as constituent elements, and it is particularly preferable to use a solid electrolyte containing Li2S-P2S5.

[0057] When a sulfide-based solid electrolyte material containing Li2S-P2S5 is used to form the solid electrolyte, the molar ratio of Li2S to P2S5 may be selected, for example, in the range of Li2S:P2S5 = 50:50 to 90:10. The solid electrolyte layer 30 may further contain a binder. Examples of binders contained in the solid electrolyte layer 30 include styrene butadiene rubber (SBR), polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyethylene (PE), and polyacrylic acid (PAA). The binder contained in the solid electrolyte layer 30 may be the same type as or different from the binders in the positive electrode active material layer 12 and the negative electrode active material layer 22.

[0058] (1-4. Current collecting part) The positive electrode current collector 11 and the negative electrode current collector 21 are connected to external wiring via current collectors. The current collectors include, for example, a positive electrode current collector 111 electrically connected to the positive electrode current collector 11, and a negative electrode current collector 211 electrically connected to the negative electrode current collector 21, as shown in Fig. 2 and Fig. 3. Fig. 3 shows the all-solid-state secondary battery according to this embodiment as viewed from the stacking direction, and Fig. 2 is a cross-sectional view of this all-solid-state secondary battery taken along line AA in Fig. 3. The positive electrode current collector 111 is, for example, a foil made of the same material as the positive electrode current collector 11. The positive electrode current collector 111 is formed integrally with the positive electrode current collector 11 so as to extend laterally from the positive electrode current collector 11. In each drawing, an imaginary line is drawn between the positive electrode current collector 11 and the positive electrode current collector 111. In this specification, "lateral" refers to, for example, a direction extending from the outer periphery of the positive electrode current collector along its surface toward the outside, and more specifically, refers to a direction perpendicular to the stacking direction of the layers constituting the all-solid-state secondary battery.

[0059] In this embodiment, a positive electrode current collector 111 electrically connected to the positive electrode current collector 11 is configured to protrude from the positive electrode current collector 11 toward the inside of the insulating layer 13. For ease of explanation, in each drawing, the direction in which this positive electrode current collector 111 protrudes is referred to as the protruding direction, and the direction perpendicular to the protruding direction in a plan view of each layer constituting the all-solid-state secondary battery 1 viewed from the stacking direction is referred to as the width direction. The negative electrode current collector 211, which is electrically connected to the negative electrode current collector 21, is, for example, a foil made of the same material as the negative electrode current collector 21. The negative electrode current collector 211 is formed integrally with the negative electrode current collector 21 so as to extend from the negative electrode current collector 21. In FIG. 3, an imaginary line is drawn between the negative electrode current collector 21 and the negative electrode current collector 211. In this embodiment, the positive electrode current collector 111 and the negative electrode current collector 211 protrude substantially parallel to each other in the protruding direction and by substantially the same length, but the protruding direction and protruding length may be the same or different from each other.

[0060] The thickness of the positive electrode current collector 111 and the negative electrode current collector 211 can be appropriately changed depending on the thickness of the positive electrode current collector 11 or the negative electrode current collector 21 integrally formed therewith, and is, for example, 1 μm or more and 50 μm or less, more preferably 5 μm or more and 30 μm or less.

[0061] (1-5. Insulating layer) The insulating layer 13 is disposed in close contact with the side end surface S of the positive electrode active material layer 12 so as to cover the entire side end surface S of the positive electrode layer 10, which is the first electrode layer in this embodiment. The insulating layer 13 is formed using an insulating layer material 13A that is an electrically non-conductive material, and has a volume resistivity of 10 12It is preferable that the electrical resistivity is Ω / cm or more. Examples of materials constituting the insulating layer material 13A include resin films containing resins such as polypropylene, polyethylene, or copolymers thereof. In addition to the polyolefin-based resin materials mentioned above, examples of resins include vinyl-based resins such as polyvinyl chloride (PVC), acrylic-based resins such as polyacetal resin and polymethyl methacrylate (PMMA), fluorine-based resins such as polycarbonate (PC), polyamide-based resins, polyurethane resins, and polytetrafluoroethylene (PTFE), as well as composite resins of these listed resins. Such a resin film can be adhered to the positive electrode layer 10 by pressure molding, such as isostatic pressing, to prevent peeling. Furthermore, it is even better if the insulating layer material 13A is a resin containing an insulating filler mixed therein. The inclusion of an insulating filler in the insulating layer material 13A improves adhesion between the insulating layer materials 13A, thereby improving the strength of the insulating layer 13 when forming the insulating layer 13 using the insulating layer material 13A and during use. Furthermore, the inclusion of an insulating filler in the insulating layer material 13A along with the resin allows for the formation of fine irregularities on the surface of the insulating layer 13 by mixing the insulating filler. The irregular shape of the surface of the insulating layer 13 also makes it more difficult for the solid electrolyte layer 30 to peel off from the insulating layer 13 when the solid electrolyte layer 30 is laminated. The insulating filler can be of various shapes, such as particulate, fibrous, needle-like, or plate-like. Among these, the use of a fibrous or nonwoven insulating filler is preferred, as it exhibits the above-mentioned effects particularly remarkably.

[0062] From the viewpoint of suppressing cost increases, it is preferable to use, as the insulating filler, one or more substances selected from the group consisting of, for example, fibrous resin, resin nonwoven fabric, alumina, magnesium oxide, silica, boehmite, barium titanate, barium carbonate, yttria, and manganese oxide.

[0063] The thickness of insulating layer 13 in the completed battery is not particularly limited, but is preferably 20 μm to 1000 μm, more preferably 50 μm to 500 μm, and particularly preferably 100 μm to 300 μm. This preferred thickness varies depending on the thickness of positive electrode layer 10, and it is suitable for insulating layer 13 to have a thickness close to that of positive electrode layer 10. When the positive electrode active material layers 12 are formed on both sides of the positive electrode current collector 11 as in the present embodiment, the insulating layers 13 are also provided in two layers so as to sandwich the positive electrode current collector 11 and the positive electrode current collector 111 from both sides, similar to the positive electrode active material layers 12. It is preferable that the total thickness of the two insulating layers 13 sandwiching the positive electrode current collector 11 and the positive electrode current collector 111 in this manner is approximately the same as the total thickness of the two positive electrode active material layers 12 formed on both sides of the positive electrode current collector 11.

[0064] (1-6. Conductive part) Therefore, the all-solid-state secondary battery 1 according to this embodiment is characterized in that the insulating layer 13 includes two conductive parts (positive electrode conductive part 141 and negative electrode conductive part 142) that electrically connect the above-mentioned positive electrode current collecting part 111 and negative electrode current collecting part 211 to external wiring, respectively, as shown in FIG. 2 or FIG. The positive electrode conductive part 141 (also referred to as the first conductive part since the positive electrode layer 10 is the first electrode layer) electrically connects the positive electrode current collector 111 and external wiring, and the negative electrode conductive part 142 (also referred to as the second conductive part since the negative electrode layer 20 is the second electrode layer) electrically connects the negative electrode current collector 211 and external wiring.

[0065] These conductive portions 141, 142 are provided so as to penetrate the insulating layer 13 in the thickness direction at positions where they are not in direct electrical contact with the positive electrode layer 10 and the negative electrode layer 20. In addition, the positive electrode conductive portion 141 and the negative electrode conductive portion 142 are formed at positions where they are not in electrical contact with each other. The conductive portions 141 and 142 are formed, for example, from a sheet-like conductive member made of a conductive material.

[0066] The thickness of the conductive parts 141, 142 is preferably 30% or more and 200% or less, more preferably 50% or more and 150% or less, and particularly preferably 80% or more and 120% or less of the thickness of the parts of the insulating layer 13 other than the conductive parts 141, 142, so that the positive electrode current collecting part 111 or the negative electrode current collecting part 211 can easily come into contact with them.

[0067] In order to fully demonstrate the performance of the all-solid-state secondary battery 1, the material forming the conductive parts 141 and 142 is selected from the conductive materials having an electrical conductivity of 10 6 S / m or more is preferable. The material forming these conductive portions 141, 142 is preferably a conductive substance having electrochemical reduction resistance or oxidation resistance, such as a composite containing one or more substances selected from the group consisting of metals, alloys, metal powders, carbon materials, and electronically conductive polymers, or a composite containing any of these substances and a resin. Examples of the metal include aluminum, nickel, copper, and stainless steel (SUS). The positive electrode conductive portion 141 and the negative electrode conductive portion 142 may be made of the same material or different materials. The positive electrode conductive portion 141 is preferably made of aluminum or SUS, and the negative electrode conductive portion 142 is preferably made of nickel, copper, or SUS. The positive electrode conductive portion 141 and the negative electrode conductive portion 142 may have the same thickness or different thicknesses.

[0068] More specifically, when the all-solid-state secondary battery 1 is in use, the positive electrode current collector 11 is connected to external wiring via a positive electrode current collecting portion 111 attached to or extended from one end of the positive electrode current collector 11, a positive electrode conductive portion 141, and a terminal (current collecting tab) (not shown) attached to the positive electrode conductive portion 141. Similarly, when the all-solid-state secondary battery 1 is in use, the negative electrode current collector 21 is connected to wiring via a negative electrode current collecting portion 211 attached to or extended from one end of the negative electrode current collector 21, a negative electrode conductive portion 142, and a terminal (current collecting tab) (not shown) attached to the negative electrode conductive portion 142.

[0069] 2. Manufacturing method for all-solid-state secondary batteries Next, an example of a method and procedure for manufacturing the all solid state secondary battery 1 according to this embodiment will be described with reference to Figures 4 to 8. Figures 4, 7, and 8 show cross-sectional views of an all solid state secondary battery in the process of being manufactured, taken along line AA in Figure 3.

[0070] The method for manufacturing the all-solid-state secondary battery 1 according to this embodiment includes the following steps. (2-1. Preparation of the positive electrode layer) Materials constituting the positive electrode active material layer 12 (such as the positive electrode active material and binder) are added to a non-polar solvent to prepare a positive electrode active material layer coating liquid (this positive electrode active material layer coating liquid may be in the form of a slurry or a paste. The same applies to coating liquids used to form other layers). Next, as shown in FIG. 4(a), the obtained positive electrode active material layer coating liquid is applied to both surfaces of the positive electrode current collector 11 and dried, and then the positive electrode current collector 11 and the applied positive electrode active material layer 12 are punched into a rectangular plate using a Thomson blade or the like. The laminate obtained in this manner is called a positive electrode layer structure. This positive electrode structure is placed on an aluminum plate on which a PET film is laid, and two sheets of insulating layer material 13A that form the insulating layer 13 around this positive electrode structure are arranged one by one so as to sandwich each positive electrode active material layer 12. A PET film is then placed on top of the entire structure, and the structure is laminated and packed and subjected to a pressure treatment using isostatic pressure (isostatic pressing) to apply pressure from the stacking direction, thereby producing the positive electrode layer-insulating layer composite 10A shown in Figure 4(b).

[0071] In this embodiment, the insulating layer material 13A described above is a conductive-member-embedded gasket 13A in which a conductive member is embedded, as shown in FIGS. 5(a) and 5(b). FIG. 5(a) is a schematic diagram of the conductive-member-embedded gasket 13A viewed from the stacking direction, and FIG. 5(b) is a cross-sectional view of the conductive-member-embedded gasket 13A taken along line BB in FIG. 5(a). The conductive-member-embedded gasket 13A can be fabricated, for example, by embedding a conductive member in a conductive-member-embedded gasket 13B formed by punching an insulating resin film. The conductive-member-embedded gasket 13B has, for example, two embedding holes 13C for embedding conductive members that form the conductive portions 141 and 142, and an accommodation hole 13D for accommodating the positive-electrode active material layer 12, as shown in FIGS. 6(a) and 6(b). FIG. 6(a) is a schematic diagram of the gasket 13A after embedding of conductive members, as viewed from the stacking direction, and FIG. 6(b) is a cross-sectional view of the gasket 13A after embedding of conductive members, taken along line CC in FIG. 6(a). The gasket 13B before embedding of conductive members has a ring-shaped portion 13E having a receiving hole 13D large enough to surround the positive electrode active material layer 12, and an extension portion 13F extending laterally from the ring-shaped portion 13E with the same thickness as the ring-shaped portion 13E. Two embedding holes 13C are formed in the extension portion 13F. After embedding conductive members of the same shape or smaller than the embedding holes 13C and the same thickness as the gasket 13B before embedding of conductive members into the two embedding holes 13C, the resin film surrounding the conductive members is heated and melted to integrate the gasket 13B before embedding of conductive members and the conductive members, thereby producing the gasket 13A after embedding conductive members. The integration process can also be carried out by applying adhesive between embedding hole 13C and conductive portions 141 and 142 to join them together.

[0072] (2-2. Preparation of negative electrode layer) A coating solution for the negative electrode active material layer is prepared by adding materials (negative electrode active material, binder, etc.) constituting the negative electrode active material layer 22 to a polar solvent or a non-polar solvent. Then, as shown in Fig. 7(a), the obtained coating solution for the negative electrode active material layer is applied to the negative electrode current collector 21 and dried. This is punched into a rectangular plate shape using a Thomson blade or the like to prepare the negative electrode layer 20.

[0073] (2-3. Preparation of solid electrolyte layer) The solid electrolyte layer 30 can be made of a solid electrolyte formed from a sulfide-based solid electrolyte material. The method for making the solid electrolyte is as follows.

[0074] First, the starting material is treated by melt quenching or mechanical milling. For example, when using the melt quenching method, a sulfide-based solid electrolyte material can be produced by mixing predetermined amounts of starting materials (e.g., Li2S, P2S5, etc.), forming them into pellets, reacting them in a vacuum at a predetermined reaction temperature, and then quenching them. The reaction temperature for the Li2S and P2S5 mixture is preferably 400°C to 1000°C, more preferably 800°C to 900°C. The reaction time is preferably 0.1 hours to 12 hours, more preferably 1 hour to 12 hours. The quenching temperature for the reaction product is usually 10°C or lower, preferably 0°C or lower, and the quenching rate is usually about 1°C / sec to 10,000°C / sec, preferably about 1°C / sec to 1000°C / sec.

[0075] Furthermore, when mechanical milling is used, a sulfide-based solid electrolyte material can be produced by stirring and reacting starting materials (e.g., Li2S, P2S5, etc.) using a ball mill or the like. The stirring speed and stirring time in mechanical milling are not particularly limited, but the faster the stirring speed, the faster the rate at which the sulfide-based solid electrolyte material is produced, and the longer the stirring time, the higher the conversion rate of the raw materials to the sulfide-based solid electrolyte material.

[0076] The mixed raw material obtained by melt quenching or mechanical milling is then heat-treated at a predetermined temperature and pulverized to produce a particulate solid electrolyte. If the solid electrolyte has a glass transition temperature, the heat treatment may change it from amorphous to crystalline.

[0077] Next, a solid electrolyte layer coating liquid is prepared containing the solid electrolyte obtained by the above method, other additives such as a binder, and a dispersion medium. A general-purpose nonpolar solvent such as xylene or diethylbenzene can be used as the dispersion medium. Alternatively, a polar solvent that is relatively unreactive with the solid electrolyte can be used. The concentrations of the solid electrolyte and other additives can be adjusted appropriately depending on the composition of the solid electrolyte layer 30 to be formed and the viscosity of the liquid composition.

[0078] The liquid composition of the solid electrolyte described above is applied with a blade onto a PET film whose surface has been subjected to a release treatment, and after drying, a solid electrolyte sheet is produced in which a solid electrolyte layer 30 is formed on the PET film.

[0079] (2-4.Lamination process) As shown in FIG. 7(a), a solid electrolyte sheet punched to have the same shape as or a larger shape than the anode layer 20 is laminated on one side of the anode layer 20 prepared as described above, and these are isostatically pressed to tightly adhere and integrate the anode layer 20 and the solid electrolyte layer 30, as shown in FIG. 7(b). If the solid electrolyte layer 30 has a larger shape than the anode layer 20, the portion of the solid electrolyte layer 30 that protrudes outward when laminated on the anode layer 20 can be removed. This laminate is referred to as an electrolyte anode structure 20A. Next, as shown in Fig. 8(a), the above-mentioned cathode layer-insulating layer composite 10A is laminated on both sides so as to be sandwiched between two electrolyte anode structures 20A. At this time, the electrolyte anode structures 20A are laminated so that the solid electrolyte layers 30 of the electrolyte anode structures 20A contact both sides of the cathode layer 10, and the whole is laminate-packed and isostatically pressed to produce an all-solid-state secondary battery 1 as shown in Fig. 8(b).

[0080] 3, in the lamination step described above, one side of the outer edge 1E of the insulating layer 13 extends outward beyond the positive electrode current collector 111 and the negative electrode current collector 211 in the protruding direction of the positive electrode current collector 111 and the negative electrode current collector 211. In the description of the present embodiment, the entire side of the outer edge 1E of the insulating layer 13 in the protruding direction is aligned at the same position, but the outer edge 1E of the insulating layer 13 may be shaped so that it extends in the protruding direction only in the portion where the positive electrode current collector 111 and the negative electrode current collector 211 protrude.

[0081] As described above, even if the outer edge 1E of the insulating layer 13 protrudes only in the portions where the positive electrode current collector 111 and the negative electrode current collector 211 protrude, it is preferable that the entire outer edge 1E in the protruding direction be located outside the outer edge of the outer edge 2E of the negative electrode layer 20. Furthermore, stacking the negative electrode layer 2 so that the outer edge 2E is located on the insulating layer 13 is preferable because this can prevent a short circuit due to physical contact between the positive electrode layer 10 and the negative electrode layer 20 even if the negative electrode layer 20 is pressed against the positive electrode layer 10 by external pressure and deformed.

[0082] 3, the outer edge 1E of the insulating layer 13 refers to the outermost edge (outer edge) in the direction perpendicular to the stacking direction of the side end face of the insulating layer 13. Furthermore, the outer edge 2E of the negative electrode layer 20 refers to the outermost edge (outer edge) in the direction perpendicular to the stacking direction of the side end face of the negative electrode layer 20, and in this embodiment, for example, refers to the outermost edge in the direction perpendicular to the stacking direction of the side end face of the negative electrode current collector 21 or the negative electrode active material layer 22.

[0083] In this way, it is preferable that the thickness of the insulating layer 13 in the extending portion 13F that extends to support the positive electrode current collecting portion 111 and the negative electrode current collecting portion 211 is the same as the thickness of the insulating layer 13 in the ring-shaped portion 13E described above. By configuring it in this manner, during isostatic pressing described below, this insulating layer 13 can support and protect the positive electrode current collecting portion 111 and the negative electrode current collecting portion 211 from at least one side thereof, and the entire surface of the positive electrode current collecting portion 111 and the negative electrode current collecting portion 211 as smoothly as possible without any steps.

[0084] (2-5. Isostatic pressing) The above-mentioned pressure treatment (pressing step) using isostatic pressing will be described below. The isostatic pressing is performed by placing a support plate such as a SUS plate on at least one side of the laminate. This isostatic pressing allows pressure to be applied from the stacking direction to each laminate that forms the cathode layer-insulating layer composite 10A, the electrolyte anode structure 20A, or the all-solid-state secondary battery 1. Examples of pressure media for isostatic pressing include liquids such as water and oil, powder, etc. It is more preferable to use a liquid as the pressure media. The pressure in the isostatic pressing is not particularly limited, but can be, for example, 10 to 1000 MPa, preferably 100 to 500 MPa. The pressing time is also not particularly limited, but can be, for example, 1 to 120 minutes, preferably 5 to 30 minutes. The temperature of the pressure medium during pressing is also not particularly limited, but can be, for example, 20 to 200°C, preferably 50 to 100°C. During isostatic pressing, the stack constituting the all-solid-state secondary battery 1 is preferably laminated with a resin film or the like together with the support plate to be isolated from the external atmosphere. Compared to other pressing methods such as roll pressing, isostatic pressing is advantageous in that it can suppress cracking of each layer constituting the all-solid-state secondary battery 1, prevent warping of the all-solid-state secondary battery 1, and enable high-pressure pressing without increasing the electrode area.

[0085] In this embodiment, two gaskets 13A after embedding of conductive members are prepared as shown in Fig. 5, and these two gaskets 13A after embedding of conductive members are arranged so as to cover the side peripheral surfaces of two positive electrode active material layers 12, respectively, and then subjected to isostatic pressure treatment, thereby covering and supporting the entire positive electrode current collector 111 from both sides so as to sandwich the entire positive electrode current collector 111 between the insulating layers 13 in the stacking direction of the layers, as shown in Fig. 9. At this time, the gaskets 13A after embedding of conductive members are arranged so that the positive electrode conductive portion 141 formed on the insulating layers 13 is in contact with the positive electrode current collector 111, and the negative electrode conductive portion 142 is in contact with the negative electrode current collector 211, respectively. 1, 2, and 8, it appears that there is a gap between the negative electrode current collector 211 and the insulating layer 13, but when they are stacked, there is actually almost no gap between them, and when pressure is applied, the entire negative electrode current collector 211 is pressed against the insulating layer 13, so that it is supported from one side by the insulating layer 13, and the positive electrode current collector 111 is pressed and fixed against the positive electrode conductive part 141, and the negative electrode current collector 211 is pressed and fixed against the negative electrode conductive part 142. Note that FIG. 9(a) is a schematic diagram of the gasket 13A and the positive electrode layer 10 after embedding the conductive member from the stacking direction, and FIG. 9(b) is a cross-sectional view of the gasket 13A and the positive electrode layer 10 after embedding the conductive member taken along line DD in FIG. 9(a).

[0086] As described above, the positive electrode current collecting portion 111 and the negative electrode current collecting portion 211 are supported on at least one side by an insulating layer, and isostatic pressure is applied to compress and bond all of the layers constituting the all-solid-state secondary battery 1, thereby forming the all-solid-state secondary battery 1.

[0087] 3. Effects of the All-Solid-State Secondary Battery According to the Present Embodiment Since the all-solid-state secondary battery 1 is composed of a large portion of powder material forming each layer, if it is manufactured without pressure treatment such as isostatic pressing, for example, voids in the solid electrolyte layer can create paths connecting the positive and negative electrodes, easily causing short circuits. Furthermore, small gaps between powder particles can create depressions or irregularities on the surface of each layer, preventing sufficient electrical conductivity and ionic conductivity. According to the manufacturing method of the all-solid-state secondary battery 1 of this embodiment, the entire battery is molded by isostatic pressing, minimizing voids within the electrodes and solid electrolyte of the all-solid-state secondary battery 1 and surface irregularities. As a result, in a stacked all-solid-state secondary battery in which multiple all-solid-state secondary batteries 1 are stacked, the formation of conductive paths within the all-solid-state secondary battery 1 and current concentration at only the protruding portions can be avoided.

[0088] In this way, if it is possible to avoid current concentration on only a part of the surface of the all-solid-state secondary battery 1 and sufficient electrical conductivity and ionic conductivity can be ensured, the entire positive electrode layer 10 and the negative electrode layer 20 will contribute to charge and discharge, and the charge and discharge capacity of the laminated all-solid-state secondary battery can be improved. Furthermore, since the positive electrode layer 10 and the negative electrode layer 20 contribute uniformly to charge and discharge over their entirety, it is possible to prevent, for example, metallic lithium and the like from being concentrated and deposited in only certain areas, and as a result, it is also possible to prevent short circuits caused by the deposition of metallic lithium. Furthermore, during isostatic pressing, the entire surfaces of the positive electrode current collecting portion 111 and the negative electrode current collecting portion 211 are supported on both sides or one side by the insulating layer 13, which prevents cracks from occurring in the positive electrode current collecting portion 111 and the negative electrode current collecting portion 211 and prevents the positive electrode current collecting portion 111 and the negative electrode current collecting portion 211 from being cut. As a result, a highly reliable all-solid-state secondary battery 1 and a laminated all-solid-state secondary battery can be manufactured without the need to reconnect the positive electrode current collector 111 or the negative electrode current collector 211 to the positive electrode current collector 11 or the negative electrode current collector 21. Furthermore, the insulating layer 13 is provided with two conductive parts that penetrate the insulating layer 13 and electrically connect the positive electrode current collecting part 111 and the negative electrode current collecting part 211 to external wiring or the like, respectively. Therefore, even if the positive electrode current collecting part 111 is covered on both sides with the insulating layer 13, the all-solid-state secondary battery can be used as is without taking the time to cut out part of the insulating layer 13.

[0089] <4. Manufacturing method of laminated all-solid-state secondary battery> By stacking a plurality of all-solid-state secondary batteries 1 manufactured as described above, it is possible to manufacture a stacked all-solid-state secondary battery that sufficiently maintains cycle characteristics and is less likely to cause a short circuit, even when, for example, three or four or more all-solid-state secondary batteries 1 are stacked. When stacking the all solid state secondary batteries 1, if the positions of the conductive parts 141, 142 provided on the insulating layer 13 of the multiple all solid state secondary batteries 1 are aligned in the stacking direction for the positive electrode conductive parts 141 and the negative electrode conductive parts 142, then the positive electrode conductive parts 141 and the negative electrode conductive parts 142 provided on the respective all solid state secondary batteries 1 can be electrically connected to each other simply by stacking them and applying pressure or welding, thereby saving the effort of cutting out part of the insulating layer covered by the current collecting part in order to electrically connect these individual all solid state secondary batteries 1 by wiring.

[0090] 5. Charging and discharging of the all-solid-state secondary battery according to this embodiment Charging and discharging of the all-solid-state secondary battery 1 according to this embodiment will be described below. In the all-solid-state secondary battery 1 according to this embodiment, in the early stage of charging, the negative electrode active material in the negative electrode active material layer 22, which forms an alloy or compound with lithium, forms an alloy or compound with lithium ions, thereby occluding lithium in the negative electrode active material layer 22. After the charge capacity of the negative electrode active material layer 22 is exceeded, metallic lithium is deposited on one or both surfaces of the negative electrode active material layer 22, forming a metallic lithium layer. Because the metallic lithium is formed by diffusing through the negative electrode active material capable of forming an alloy or compound, it is not dendritic (dendrite-like) but is uniformly formed mainly between the negative electrode active material layer 22 and the negative electrode current collector 21. During discharge, metallic lithium ionizes from the negative electrode active material layer 22 and the metallic lithium layer and migrates toward the positive electrode active material layer 12. Consequently, metallic lithium itself can be used as the negative electrode active material, thereby improving energy density.

[0091] Furthermore, when the metallic lithium layer is formed between the negative electrode active material layer 22 and the negative electrode current collector 21, i.e., inside the negative electrode layer 20, the negative electrode active material layer 22 covers the metallic lithium layer. As a result, the negative electrode active material layer 22 functions as a protective layer for the metallic lithium layer. This suppresses short circuits and capacity reduction in the all-solid-state secondary battery 1, and ultimately improves the characteristics of the all-solid-state secondary battery 1.

[0092] An example of a method for enabling the deposition of metallic lithium in the negative electrode active material layer 22 is to make the charge capacity of the positive electrode active material layer 12 larger than the charge capacity of the negative electrode active material layer 22. Specifically, the ratio (capacity ratio) of the charge capacity of the positive electrode active material layer 12 to the charge capacity of the negative electrode active material layer 22 satisfies the requirement of the following mathematical formula (1). 0.002 a: Charging capacity (mAh) of the positive electrode active material layer 12 b: Charging capacity (mAh) of the negative electrode active material layer 22

[0093] ​When the capacity ratio expressed by the above formula (1) is greater than 0.002, the anode active material layer 22 can sufficiently mediate the deposition of metallic lithium from lithium ions, regardless of the configuration of the anode active material layer 22, and therefore the metallic lithium layer is more likely to be formed appropriately. Furthermore, when the metallic lithium layer is formed between the anode active material layer 22 and the anode current collector 21, the anode active material layer 22 can sufficiently function as a protective layer, which is preferable. Therefore, the capacity ratio is more preferably 0.01 or greater, and even more preferably 0.03 or greater.

[0094] Furthermore, when the capacity ratio is less than 0.5, the negative electrode active material layer 22 does not store most of the lithium during charging, and therefore a metallic lithium layer can be easily formed uniformly regardless of the configuration of the negative electrode active material layer 22. The capacity ratio is more preferably 0.2 or less, and even more preferably 0.1 or less.

[0095] The capacity ratio is preferably greater than 0.01. If the capacity ratio is 0.01 or less, the characteristics of the all-solid-state secondary battery 1 may be degraded. One reason for this is that the anode active material layer 22 may not function adequately as a protective layer. For example, if the thickness of the anode active material layer 22 is very thin, the capacity ratio may be 0.01 or less. In this case, repeated charge / discharge cycles may cause the anode active material layer 22 to collapse, leading to the precipitation and growth of dendrites. This may result in a deterioration in the characteristics of the all-solid-state secondary battery 1. Furthermore, the capacity ratio is preferably less than 0.5. If the capacity ratio is 0.5 or more, the amount of lithium precipitation in the anode layer 20 may decrease, potentially reducing the battery capacity. For the same reason, it is considered more preferable that the capacity ratio be less than 0.25. A capacity ratio of less than 0.25 can further improve the battery output characteristics.

[0096] Here, the charge capacity of the positive electrode active material layer 12 is obtained by multiplying the specific charge capacity (mAh / g) of the positive electrode active material by the mass of the positive electrode active material in the positive electrode active material layer 12. When multiple types of positive electrode active materials are used, the value of specific charge capacity x mass is calculated for each positive electrode active material, and the sum of these values ​​is taken as the charge capacity of the positive electrode active material layer 12. The charge capacity of the negative electrode active material layer 22 is also calculated in a similar manner. That is, the charge capacity of the negative electrode active material layer 22 is obtained by multiplying the specific charge capacity (mAh / g) of the negative electrode active material by the mass of the negative electrode active material in the negative electrode active material layer 22. When multiple types of negative electrode active materials are used, the value of specific charge capacity x mass is calculated for each negative electrode active material, and the sum of these values ​​is taken as the capacity of the negative electrode active material layer 22. Here, the specific charge capacities of the positive electrode active material and the negative electrode active material are capacities estimated using an all-solid-state half cell using lithium metal as the counter electrode. In practice, the charge capacities of the positive electrode active material layer 12 and the negative electrode active material layer 22 are directly measured by measurement using an all-solid-state half cell.

[0097] Specific methods for directly measuring the charge capacity include the following. First, the charge capacity of the positive electrode active material layer 12 is measured by fabricating an all-solid-state half-cell using the positive electrode active material layer 12 as the working electrode and Li as the counter electrode, and performing CC-CV charging from the open circuit voltage (OCV) to an upper charge voltage. The upper charge voltage is defined in JIS C 8712:2015, and refers to 4.25 V for a positive electrode active material layer 12 using a lithium cobalt oxide-based positive electrode active material, and the voltage determined by applying the provisions of A.3.2.3 (Safety Requirements When Applying a Different Upper Charge Voltage) of JIS C 8712:2015 for a positive electrode active material layer 12 using a different positive electrode active material. The charge capacity of the negative electrode active material layer 22 is measured by fabricating an all-solid-state half-cell using the negative electrode active material layer 22 as the working electrode and Li as the counter electrode, and performing CC-CV charging from the open circuit voltage (OCV) to 0.01 V.

[0098] The specific charge capacity is calculated by dividing the charge capacity measured in this manner by the mass of each active material. The charge capacity of the positive electrode active material layer 12 may be an initial charge capacity measured during charging in the first cycle.

[0099] In an embodiment of the present invention, the charge capacity of the positive electrode active material layer 12 is set to be excessive relative to the charge capacity of the negative electrode active material layer 22. As will be described later, in this embodiment, the all-solid-state secondary battery 1 is charged beyond the charge capacity of the negative electrode active material layer 22. That is, the negative electrode active material layer 22 is overcharged. At the initial stage of charging, lithium is absorbed into the negative electrode active material layer 22. That is, the negative electrode active material forms an alloy or compound with lithium ions that have migrated from the positive electrode layer 10. When charging is performed beyond the capacity of the negative electrode active material layer 22, lithium is precipitated on the back side of the negative electrode active material layer 22, i.e., between the negative electrode current collector 21 and the negative electrode active material layer 22, and this lithium forms a metallic lithium layer.

[0100] This phenomenon occurs when the negative electrode active material is made of a specific substance, i.e., a substance that forms an alloy or compound with lithium. During discharge, lithium in the negative electrode active material layer 22 and the metallic lithium layer ionizes and moves toward the positive electrode layer 10. Therefore, metallic lithium can be used as the negative electrode active material in the all-solid-state secondary battery 1. More specifically, when the charge capacity of the negative electrode layer 20 (the total charge capacity of the charge capacities exerted by the negative electrode active material layer 22 and the metallic lithium layer) is taken as 100%, it is preferable that 80% or more of the charge capacity be exerted by the metallic lithium layer.

[0101] Furthermore, the negative electrode active material layer 22 covers the metallic lithium layer from the side of the solid electrolyte layer 30, and therefore functions as a protective layer for the metallic lithium layer and can suppress the precipitation and growth of dendrites, thereby more efficiently suppressing short circuits and capacity reduction in the all-solid-state secondary battery 1, and ultimately improving the characteristics of the all-solid-state secondary battery 1.

[0102] 6. Other embodiments of the present invention The all-solid-state secondary battery according to the present invention is not limited to the one described above. For example, the first electrode layer may be a negative electrode layer, and the second electrode layer may be a positive electrode layer.

[0103] In the above embodiment, an insulating layer is disposed on the side end surface of the first polar layer, but an insulating layer may also be provided on the side end surface of the second polar layer. The solid electrolyte layer 30 provided between the positive electrode layer and the negative electrode layer may be formed by laminating at least one layer, or may be formed by laminating two, three, four or more layers. As shown in FIG. 10, an all-solid-state secondary battery may be configured in which a solid electrolyte layer is laminated on only one surface of a first electrode layer, and a second electrode layer is formed on this solid electrolyte layer. The present invention is not limited to all-solid-state lithium ion secondary batteries, but can be widely applied to all-solid-state secondary batteries that have a foil-shaped current collecting portion and are manufactured by molding using a pressure treatment such as isostatic pressing. [Example]

[0104] Example 1 [Fabrication of positive electrode layer structure] LiNi as a positive electrode active material 0.8 Co 0.15 Al 0.05 O2(NCA) ternary powder, Li2S-P2S5 (80:20 mol%) amorphous powder as a sulfide-based solid electrolyte, and vapor-grown carbon fiber powder as a positive electrode layer conductive material (conductive additive) were weighed in a mass ratio of 60:35:5 and mixed using a planetary mixer. Next, a dehydrated xylene solution in which SBR was dissolved as a binder was added to this mixed powder so that the SBR content was 5.0% by mass relative to the total mass of the mixed powder, thereby preparing a primary mixed liquid. A second mixed liquid was prepared by adding an appropriate amount of dehydrated xylene to this first mixed liquid to adjust the viscosity. Furthermore, to improve the dispersibility of the mixed powder, zirconia balls with a diameter of 5 mm were added to the secondary mixed liquid so that the space, mixed powder, and zirconia balls each occupied one-third of the total volume of the kneading vessel. The tertiary mixed liquid thus produced was placed in a planetary centrifugal mixer and stirred at 3000 rpm for 3 minutes to produce a coating liquid for a positive electrode active material layer.

[0105] Next, a 20 μm thick aluminum foil current collector was prepared as the positive electrode current collector 11. The positive electrode current collector 11 was placed in a desktop screen printer, and the positive electrode active material layer coating liquid was applied to the sheet using a 150 μm thick metal mask. The sheet coated with the positive electrode active material layer coating liquid was then dried on a hot plate at 60°C for 30 minutes, after which the coating was applied to the back side, and the sheet was further dried on a hot plate at 60°C for 30 minutes, followed by vacuum drying at 80°C for 12 hours. This was punched into a rectangular plate using a Thomson blade, forming positive electrode active material layers 12 on both sides of the positive electrode current collector 11. The total thickness of the positive electrode current collector 11 and the positive electrode active material layer 12 after drying was approximately 330 μm.

[0106] The positive electrode current collector 11 and the positive electrode active material layer 12 were placed on a 3 mm thick aluminum plate (support material) with a release-treated PET film (hereinafter referred to as release film) attached to the surface. Two gaskets 13A after embedding the conductive material were arranged so that their ring-shaped portions 13E surrounded the positive electrode active material layer 12 and their extending portions 13F sandwiched the positive electrode current collector portion 111 protruding from the positive electrode current collector 11 from both sides. The resulting product was then covered with a release film, and further covered with a 0.3 mm thick SUS metal plate (support material) having the same shape as the combined shape of the positive electrode active material layer and the ring-shaped portions of the gaskets 13A after embedding the conductive material, i.e., a shape that did not cover the extending portions of the gaskets after embedding the conductive material. The product, including the support material, was then vacuum laminated and packed. The gasket 13A was submerged in a pressurizing medium and subjected to a hydrostatic pressure treatment (a compaction process using an isostatic press) at 490 MPa, thereby integrating the ring-shaped portion 13E of the gasket 13A with the positive electrode current collector 11 and the positive electrode active material layer 12 after embedding the conductive member. At this time, the positive electrode conductive portion 13E1 was in contact with the positive electrode current collector 111 formed so as to protrude from the positive electrode current collector 11. A composite including a positive electrode layer 10 in which positive electrode active material layers 12 are stacked on both sides of this positive electrode current collector 11 and an insulating layer 13 covering the side surfaces of these positive electrode active material layers 12 in a direction different from the stacking direction will be referred to as a positive electrode layer-insulating layer composite 10A.

[0107] The gasket 13A after embedding of the conductive member described above was fabricated as follows. An insulating resin film was punched using, for example, a Pinnacle Die (registered trademark) to produce a gasket 13B before embedding of the conductive member, which had an embedding hole 13C for embedding the conductive member forming the conductive portions 141 and 142 and an accommodation hole 13D for accommodating the positive electrode active material layer 12 therein. The insulating resin film used in this example was manufactured by Dai Nippon Printing Co., Ltd. and contains a resin nonwoven fabric as an insulating filler. As shown in FIG. 6, the gasket 13B before embedding of the conductive member had a ring-shaped portion 13E having an accommodation hole 13D large enough to surround the positive electrode active material layer 12 from which a rectangular extension portion 13F protecting the current collecting portion (111, 211) extended in one direction. Two of the aforementioned embedding holes 13C were formed independently in the center of this extension portion 13F at positions that contact the positive electrode current collector 111 and the negative electrode current collector 211, respectively. Subsequently, a conductive member having the same shape as the embedding hole 13C and the same thickness as the gasket 13B before embedding the conductive member was embedded. The resin film surrounding the conductive member was then heated to melt the resin film, thereby integrating the gasket 13B before embedding the conductive member and the conductive member, thereby obtaining a gasket 13A after embedding the conductive member, which includes conductive portions 141 and 142. In this example, aluminum foil was used as the conductive member forming the positive electrode conductive portion 141 that contacts the positive electrode current collector 111, and nickel foil was used as the conductive member forming the negative electrode conductive portion 142 that contacts the other negative electrode current collector 211.

[0108] [Creating the negative electrode layer] A nickel foil current collector having a thickness of 10 μm was prepared as the negative electrode current collector 21. CB1 (nitrogen adsorption specific surface area: approximately 339 m) manufactured by Asahi Carbon Co., Ltd. was used as the negative electrode active material. 2 / g, DBP oil supply amount is about 193 ml / 100 g), Asahi Carbon CB2 (nitrogen adsorption specific surface area is about 52 m 2 The silver particles were prepared using a DBP oil supply of approximately 193 ml / 100 g and a particle size of 60 nm. The particle size of the silver particles was measured using, for example, a laser particle size distribution system, and the median diameter (so-called D50) was used. Next, 1.5 g of CB1, 1.5 g of CB2, and 1 g of silver particles were placed in a container, and 4 g of an N-methylpyrrolidone (NMP) solution containing 5% by weight of a binder (#9300 manufactured by Kureha Corporation) was added. Next, a total of 30 g of NMP was gradually added to this mixed solution while stirring, to prepare a negative electrode active material layer coating solution. This negative electrode active material layer coating solution was applied to a Ni foil using a blade coater and dried in air at 80°C for approximately 20 minutes to form a negative electrode active material layer 22. The resulting laminate was vacuum dried at 100°C for approximately 12 hours and punched using a Pinnacle Die (registered trademark). Through the above process, a negative electrode layer 20 was prepared.

[0109] [Fabrication of solid electrolyte sheets] First, a solid electrolyte layer coating liquid was prepared. A primary mixed slurry was prepared by adding SBR binder dissolved in dehydrated xylene to amorphous powder of Li2S-P2S5 (80:20 mol%) as a sulfide-based solid electrolyte at a ratio of 1 mass% relative to the solid electrolyte. Furthermore, to this primary mixed slurry, appropriate amounts of dehydrated xylene and dehydrated diethylbenzene were added to adjust the viscosity to prepare a secondary mixed slurry. Furthermore, to improve the dispersibility of the mixed powder, 5 mm diameter zirconia balls were added to the tertiary mixed slurry so that the air space, mixed powder, and zirconia balls each occupied 1 / 3 of the total volume of the kneading vessel. The resulting tertiary mixed liquid was then placed in a planetary mixer and stirred at 3000 rpm for 3 minutes to produce the solid electrolyte layer coating liquid. The prepared solid electrolyte layer coating solution was applied with a blade onto a PET film whose surface had been treated with a release agent, and then dried on a hot plate at 40°C for 10 minutes. It was then dried in a vacuum at 40°C for 12 hours to obtain a solid electrolyte sheet. The thickness of the solid electrolyte layer after drying was approximately 65 μm. The dried solid electrolyte sheet was punched out with a Thomson blade to the specified size.

[0110] [Fabrication of electrolyte negative electrode structure] A solid electrolyte sheet was placed on the surface of the anode layer 20 so that the solid electrolyte layer 30 and the anode active material layer 22 were in contact with each other, and then they were placed on a 3 mm thick aluminum plate (support material) with a release film attached, and vacuum laminate packing was performed, including the support material. The solid electrolyte layer on the solid electrolyte sheet was integrated with the anode layer 20 by submerging it in a pressurized medium and performing a hydrostatic pressure treatment (a consolidation process using an isostatic press) at 30 MPa. This is referred to as an electrolyte anode structure 20A.

[0111] [Fabrication of all-solid-state secondary batteries] The positive electrode layer-insulating layer composite 10A was sandwiched between two electrolyte negative electrode structures 20A to obtain a laminate that was the all-solid-state secondary battery 1A before pressing. At this time, the negative electrode conductive part 142 and the negative electrode current collector 211 were arranged so as to be in contact with each other. This laminate was placed on a 3 mm thick aluminum plate (support material) with a release film attached, covered with another release film, and then covered with a 0.3 mm thick SUS metal plate (support material) of the same shape as that used in the above [Preparation of the Positive Electrode Layer]. After that, the laminate including the support material was vacuum laminated and packed. The laminate was then submerged in a pressurized medium and subjected to isostatic pressure treatment (consolidation process using an isostatic press) at 490 MPa to obtain a single cell (single battery) of the all-solid-state secondary battery 1. In this embodiment, an aluminum plate and a metal plate made of SUS are used as the support material, but the material of these support materials is not particularly limited as long as it has the strength to withstand pressure treatment by isostatic pressure.

[0112] [OCV evaluation of all-solid-state secondary batteries] Next, metal tabs for connection to external terminals were welded to the positive electrode conductive part 141 and the negative electrode conductive part 142 using an ultrasonic welding machine, and then the single cell (single cell) of the all-solid-state secondary battery 1 was subjected to a vacuum laminate pack process to obtain an all-solid-state secondary battery for evaluation. In this welding, an aluminum metal tab was welded to the positive electrode conductive part 141, and a nickel metal tab was welded to the negative electrode conductive part 142. The fabricated all-solid-state battery for evaluation was connected to a low resistance meter (Tsuruga Electric Co., Ltd. Model 3566) to measure the open circuit voltage (OCV). The results are shown in Table 1. The open circuit voltage (OCV) of the all-solid-state secondary battery produced in Example 1 was within a sufficient usable range, and it was confirmed that electrical conduction between the external terminal and the all-solid-state battery could be achieved without any problems via the conductive material portion.

[0113] [Table 1]

[0114] [Charge / discharge evaluation of all-solid-state secondary batteries] The fabricated single cell of all-solid-state secondary battery 1 was sandwiched between two metal plates from the outside in the stacking direction. Screws with disc springs were inserted into holes drilled in the metal plates and tightened to apply a pressure of 1.0 MPa to the battery. The battery's characteristics were evaluated using a charge / discharge evaluation device TOSCAT-3100 under the following charge / discharge conditions: 1) welded metal tabs for connection to external terminals to the positive electrode conductive portion 141 and the negative electrode conductive portion 142, as described above, and then charged at a constant current of 0.1 C to a maximum voltage of 4.25 V at 45°C, followed by constant voltage charging down to a current of 0.05 C, and finally discharged at 0.1 C to a cutoff voltage of 2.5 V. The results of a second charge / discharge evaluation performed under the same charge / discharge conditions are shown in Figure 11.

[0115] 11, it was confirmed that the all-solid-state secondary battery produced in Example 1 was able to be charged and discharged without short-circuiting. In addition, since the designed battery capacity was realized, it was confirmed that electrical continuity with external terminals was achieved via the conductive parts 141 and 142 without any problems.

[0116] [Cycle evaluation of all-solid-state secondary batteries] In addition, to evaluate the charge-discharge cycle, as described in the charge-discharge evaluation section, the all-solid-state secondary battery in a pressurized state was charged at 45°C with a constant current of 0.33 C up to an upper limit voltage of 4.25 V, then charged at a constant voltage down to a current of 0.1 C, and discharged at 0.33 C down to a cut-off voltage of 2.5 V. The results are shown in Figure 12. From this result, it was confirmed that the all-solid-state secondary battery produced in Example 1 was cycled with stable charge and discharge without short circuiting.

[0117] Example 2 [Fabrication of laminated all-solid-state secondary batteries] Two single cells of the all-solid-state secondary battery produced in Example 1 were stacked to produce a stacked all-solid-state secondary battery. [OCV evaluation of laminated all-solid-state secondary batteries] Using this laminated all-solid-state secondary battery, an OCV evaluation was carried out in the same manner as in Example 1, and the results are shown in Table 1. An OCV of the same level as in Example 1 was observed. [Charge / discharge evaluation of laminated all-solid-state secondary batteries] The results of charge / discharge evaluation performed in the same manner as in Example 1 are shown in Figure 13. From the results in Figure 13, it was confirmed that the stacked all-solid-state secondary battery in which a plurality of all-solid-state secondary batteries produced in Example 1 were stacked could be charged and discharged without short-circuiting. It was also confirmed that electrical conduction between an external terminal and the plurality of all-solid-state secondary batteries was achieved without any problems via each conductive part. [Cycle evaluation of laminated all-solid-state secondary batteries] Using the laminated all-solid-state secondary battery produced in Example 2, a charge-discharge cycle evaluation was carried out in the same manner as in Example 1. The results are shown in Figure 14. From the results in Figure 14, it was confirmed that the laminated all-solid-state secondary battery produced in Example 2 had a relatively stable charge-discharge cycle without short-circuiting.

[0118] Example 3 [Fabrication of all-solid-state secondary batteries] An all-solid-state secondary battery including one positive electrode layer, one negative electrode layer, and one solid electrolyte layer was fabricated using the same procedure as in Example 1, except that the positive electrode active material layer 12 was formed on only one surface of the positive electrode current collector 11, only one insulating layer was used, and the isostatic pressing step for integrating the positive electrode layer and the insulating layer was not performed, and the positive electrode layer, the insulating layer, and the negative electrode layer to which the solid electrolyte layer had been transferred were all stacked and then isostatic pressing was performed. [OCV evaluation of all-solid-state secondary batteries] Using this all-solid-state secondary battery, an OCV evaluation was carried out in the same manner as in Example 1, and the results are shown in Table 1. An OCV of the same level as in Example 1 was observed. [Charge / discharge evaluation of all-solid-state secondary batteries] 15 shows the results of charge / discharge evaluation carried out in the same manner as in Example 1. From these results, it was confirmed that charge / discharge was also possible without short-circuiting in Example 3. [Cycle evaluation of all-solid-state secondary batteries] Using the laminated all-solid-state secondary battery produced in Example 3, a charge-discharge cycle evaluation was carried out in the same manner as in Example 1. The results are shown in Figure 16. From the results in Figure 16, it was confirmed that the laminated all-solid-state secondary battery produced in Example 3 performed stable charge-discharge cycles without short-circuiting.

[0119] Example 4 [Fabrication of laminated all-solid-state secondary batteries] A stacked all-solid-state secondary battery was produced in the same procedure as in Example 2 using the all-solid-state secondary battery produced in Example 3. [OCV evaluation of laminated all-solid-state secondary batteries] Using this laminated all-solid-state secondary battery, an OCV evaluation was carried out in the same manner as in Example 1, and the results are shown in Table 1. An OCV of the same level as in Example 1 was observed. [Charge / discharge evaluation of laminated all-solid-state secondary batteries] 17 shows the results of charge / discharge evaluation carried out in the same manner as in Example 1. From these results, it was confirmed that charge / discharge was also possible without short-circuiting in Example 4. [Cycle evaluation of laminated all-solid-state secondary batteries] The charge-discharge cycle evaluation was carried out using the laminated all-solid-state secondary battery produced in Example 4 in the same manner as in Example 1. The results are shown in Figure 18. From the results in Figure 18, it was confirmed that the laminated all-solid-state secondary battery produced in Example 4 performed stable charge-discharge cycles without short-circuiting.

[0120] (Comparative Example 1) [Fabrication of all-solid-state secondary batteries] An insulating layer material in which no conductive portion or hole for forming a conductive portion is formed was used in the extending portion of the insulating layer (corresponding to the portion 13F), and the extending portion of the insulating layer was cut off from the produced all-solid-state secondary battery 1, and metal tabs for connecting to external terminals were directly welded to the positive electrode current collecting portion 111 and the negative electrode current collecting portion 211 to obtain a produced all-solid-state secondary battery. [OCV evaluation of all-solid-state secondary batteries] This all-solid-state secondary battery was connected to a low resistance meter (Model 3566 manufactured by Tsuruga Electric Co., Ltd.) and the open circuit voltage (OCV) was measured. The results are shown in Table 1. The all-solid-state secondary battery 1 of Comparative Example 1 has already been confirmed to have excellent battery performance in another application filed by the present inventor, Patent Application No. 2020-150093. Since the OCV of Comparative Example 1 is equivalent to the OCV of Example 1, it was confirmed that Example 1, in which the positive electrode current collector 111 and the negative electrode current collector 211 are connected to external terminals via the conductive portions 141 and 142, has performance equivalent to that of Comparative Example 1, which has already been confirmed to have excellent battery performance. [Charge / Discharge Evaluation of All-Solid State Secondary Battery] A charge / discharge test was carried out using the all-solid state secondary battery produced in Comparative Example 1 by the method described in Example 1. The results are shown in Fig. 19. Since the results are in good agreement with those in Example 1, it was confirmed that the all-solid state battery can be used without any problems even when connected to an external terminal using a method of cutting out the insulating layer 13 that protects the current collecting portion. [Cycle evaluation of all-solid-state secondary batteries] A charge-discharge cycle evaluation was performed using the all-solid-state secondary battery produced in Comparative Example 1 in the same manner as in Example 1. The results are shown in FIG. 20. From the results in FIG. 20, it was confirmed that the all-solid-state secondary battery produced in Comparative Example 1 underwent stable charge-discharge cycles without short-circuiting. This result is in good agreement with the charge-discharge cycles of the all-solid-state secondary battery produced in Example 1, and it was confirmed from this result that the all-solid-state secondary battery 1 produced in Example 1 also had no problems in charge-discharge cycles. From this result, it can be said that the all-solid-state secondary battery according to the example of the present invention has battery performance equivalent to that of Comparative Example 1 described above, and is extremely excellent in that it can eliminate the need to remove a portion of the insulating layer 13.

[0121] (Comparative Example 2) [Fabrication of all-solid-state secondary batteries] An all-solid-state battery was fabricated in the same manner as in Example 1, except that an insulating layer 13 not including the extending portion 13F supporting the current collector was used instead of the insulating layer 13 used in Example 1. In this case, the positive electrode current collector 111 was broken, and the OCV could not be measured.

[0122] (Comparative Example 3) [Fabrication of All-Solid-State Secondary Battery] The broken positive electrode current collecting part 111 in Comparative Example 2 was inserted between the insulating layers 13 and fastened with Kapton tape, thereby fixing the positive electrode current collecting part 111 so as to be in contact with the positive electrode current collector 11, thereby repairing the all-solid-state secondary battery. Thereafter, a metal tab was welded to this positive electrode current collecting part 111, and laminate packaging was performed to obtain an all-solid-state secondary battery for evaluation. [OCV evaluation of all-solid-state secondary batteries] The fabricated all-solid-state secondary battery 1 was connected to a low resistance meter (Model 3566 manufactured by Tsuruga Electric Co., Ltd.) to measure the open circuit voltage (OCV). By repairing the cut portion, an OCV similar to that of Example 1 and Comparative Example 1 was observed.

[0123] [Charge / discharge evaluation of all-solid-state secondary batteries] Using the all-solid-state secondary battery produced in Comparative Example 3, a charge-discharge test was carried out in the same manner as in Example 1. The results are shown in FIG. From the results of FIG. 21, it is considered that in Comparative Example 3, the charge capacity was excessive even in the second charge, and a small short circuit occurred.

[0124] [Cycle evaluation of all-solid-state secondary batteries] The all-solid-state secondary battery produced in Comparative Example 3 was subjected to a charge-discharge cycle evaluation in the same manner as in Example 1. The results are shown in Figure 22. The all-solid-state secondary battery produced in Comparative Example 3 experienced a decrease in Coulomb efficiency after several cycles, resulting in a short circuit. This is thought to be due to the fact that a broken current collector was repaired during the production process of the all-solid-state secondary battery, and although there was no problem with the OCV, the contact was insufficient, causing a physical problem in the all-solid-state secondary battery through this part during the charge-discharge process.

[0125] From the results of these examples and comparative examples, it was confirmed that, according to the present invention, even when pressure treatment is performed during the manufacturing process of an all-solid-state secondary battery, the positive electrode current collecting portion 111 and the negative electrode current collecting portion 211 can be made even less likely to break than conventionally by supporting them with the insulating layer 13. Furthermore, by providing the insulating layer 13 with the conductive portion 14, it was possible to electrically connect the positive electrode current collecting portion 111 and the negative electrode current collecting portion 211 to external terminals while maintaining the portion of the insulating layer 13 supporting the positive electrode current collecting portion 111 and the negative electrode current collecting portion 211 without removing it, and it was confirmed that even with this configuration, battery performance equivalent to that of a conventional all-solid-state secondary battery 1 can be exhibited. From these results, it can be said that it is now possible to manufacture an all-solid-state secondary battery 1 and a laminated all-solid-state secondary battery with fewer defects than conventionally by a simple process. [Explanation of symbols]

[0126] 1 All-solid-state secondary battery 10 Positive electrode layer 11 Positive electrode current collector 111 Positive electrode current collector 12 Cathode active material layer 13 Insulating layer 141 Positive electrode conductive part 142 Conductive part for negative electrode 20 negative electrode layer 21 Negative electrode current collector 211 Negative electrode current collector 22 Negative electrode active material layer 30 Solid electrolyte layer

Claims

1. a positive electrode layer; a negative electrode layer; a solid electrolyte layer laminated between the positive electrode layer and the negative electrode layer; an insulating layer disposed on a side end surface of the positive electrode layer so as to cover the positive electrode layer; a foil-shaped positive electrode current collecting portion protruding laterally from the positive electrode layer; a foil-shaped negative electrode current collecting portion protruding laterally from the negative electrode layer, the insulating layer supports the positive electrode current collecting portion and the negative electrode current collecting portion from at least one surface thereof, the insulating layer is provided with two conductive portions that electrically connect the positive electrode current collecting portion and the negative electrode current collecting portion to external wiring, respectively; the two conductive portions are formed so as to penetrate the insulating layer in the stacking direction, the solid electrolyte layer is laminated on each of both sides of the positive electrode layer, the negative electrode layer is laminated on a surface of each of the solid electrolyte layers opposite to the positive electrode layer, the insulating layers sandwich and support the positive electrode current collecting portion in the stacking direction.

2. The all-solid-state secondary battery according to claim 1 , wherein the two conductive portions are arranged at positions where they are not in direct electrical contact with each other.

3. The conductive portion has an electrical conductivity of 10 ６ 3. The all-solid-state secondary battery according to claim 1, wherein the battery is formed from a material having a conductivity of S / m or more.

4. 4. The all-solid-state secondary battery according to claim 1, wherein the conductive portion is made of one or more substances selected from the group consisting of metals, alloys, metal powders, carbon materials, and electronically conductive polymers, or a composite containing any one of these substances and a resin.

5. 5. The all-solid-state secondary battery in accordance with claim 4, wherein the metal is at least one selected from the group consisting of aluminum, nickel, copper, and stainless steel.

6. The insulating layer contains a resin and has a volume resistivity of 10 １２ 6. The all-solid-state secondary battery according to claim 1, wherein the resistance is Ω / cm or more.

7. 7. The all-solid-state secondary battery according to claim 6, wherein the insulating layer further contains an insulating filler.

8. 8. The all-solid-state secondary battery according to claim 7, wherein the insulating filler is made of one or more substances selected from the group consisting of fibrous resin, resin nonwoven fabric, alumina, magnesium oxide, silica, boehmite, barium titanate, barium carbonate, yttria, and manganese oxide.

9. 9. The all-solid-state secondary battery according to claim 1, wherein a part or all of an outer edge of the insulating layer in a direction in which the current collecting portion protrudes is located outside an outer edge of the negative electrode layer.

10. 10. The all-solid-state secondary battery according to claim 9, wherein a part or all of the outer edge of the negative electrode layer is disposed on the insulating layer.

11. 11. The all-solid-state secondary battery according to claim 1, wherein the solid electrolyte layer contains a sulfide-based solid electrolyte containing at least lithium, phosphorus, and sulfur.

12. 12. The all-solid-state secondary battery according to claim 1, wherein the anode layer contains an anode active material that forms an alloy with lithium and / or an anode active material that forms a compound with lithium, metallic lithium is capable of being precipitated inside the anode layer during charging, and 80% or more of the charge capacity of the anode layer is exhibited by metallic lithium.

13. 13. The all-solid-state secondary battery according to claim 1, wherein the negative electrode layer contains at least one selected from the group consisting of amorphous carbon, gold, platinum, palladium, silicon, silver, aluminum, bismuth, tin, and zinc.

14. A stacked all-solid-state secondary battery, comprising two or more stacked all-solid-state secondary batteries according to any one of claims 1 to 13.

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