Solid state battery

Abstract

Provided is a solid state battery comprising a positive electrode layer, a negative electrode layer, a solid electrolyte layer, a positive terminal electrode electrically connected to the positive electrode layer, and a negative terminal electrode electrically connected to the negative electrode layer. At least each of the positive electrode layer and the positive terminal electrode contains a carbon-based conductive material. The content of the carbon-based conductive material in the positive terminal electrode is greater than 30 vol% and less than 95 vol%.

Description

solid state battery

[0001] The present disclosure relates to solid-state batteries.

[0002] Secondary batteries that can be repeatedly charged and discharged have been used for a variety of purposes, including as power sources for electronic devices such as smartphones and laptop computers.

[0003] In secondary batteries, a liquid electrolyte is generally used as a medium for ion migration that contributes to charging and discharging. In other words, a so-called electrolytic solution is used in secondary batteries. However, such secondary batteries generally require safety in terms of preventing leakage of the electrolytic solution. In addition, organic solvents and the like used in the electrolytic solution are flammable, so safety is also required in this respect.

[0004] Therefore, research is being conducted on solid-state batteries that use solid electrolytes instead of liquid electrolytes.

[0005] Japanese Patent Application Laid-Open No. 2015-220107

[0006] The inventors of the present invention have realized that conventional solid-state batteries have problems to be overcome and have newly discovered the need to take measures to address these problems. Specifically, they have found the following problems:

[0007] A solid-state battery includes electrode layers including a positive electrode layer and a negative electrode layer, and terminal electrodes electrically connected to each of the electrode layers. Conventionally, highly conductive metal materials such as silver have been used for the electrode layers and terminal electrodes (see Patent Document 1). However, in such solid-state batteries, repeated charge and discharge can cause so-called migration, in which the metal material contained in the electrode layer or terminal electrode ionizes, migrates toward the counter electrode, and is reduced and precipitates as a metal. In some cases, this migration can cause a short circuit between the positive and negative electrodes, potentially preventing the solid-state battery from functioning properly.

[0008] The present disclosure has been made in view of the above-mentioned problems. That is, a main object of the present disclosure is to provide a solid-state battery that can suppress the occurrence of migration and function favorably as a solid-state battery.

[0009] In order to achieve the above object, a solid state battery according to one embodiment of the present disclosure includes a positive electrode layer, a negative electrode layer, a solid electrolyte layer, a positive electrode terminal electrode electrically connected to the positive electrode layer, and a negative electrode terminal electrode electrically connected to the negative electrode layer, wherein at least the positive electrode layer and the positive electrode terminal electrode each contain a carbon-based conductive material, and the content of the carbon-based conductive material in the positive electrode terminal electrode is greater than 30% by volume and less than 95% by volume.

[0010] In a solid-state battery according to an embodiment of the present disclosure, the occurrence of migration is suppressed and the battery can function favorably as a solid-state battery.

[0011] Fig. 1 is a perspective view showing a schematic appearance of a solid-state battery according to one embodiment of the present disclosure. Fig. 2 is a schematic cross-sectional view of the AA cross section of the solid-state battery shown in Fig. 1, as viewed in the direction of the arrows. Fig. 3 is a schematic cross-sectional view of the AA cross section of a solid-state battery according to another embodiment of the present disclosure.

[0012] The solid-state battery of the present disclosure will be described in detail below. While the description will be made with reference to drawings as necessary, the contents shown in the drawings are merely schematic and illustrative for understanding the present disclosure, and the appearance, dimensional ratios, etc. may differ from the actual product. The applicant provides the following description and examples to enable those skilled in the art to fully understand the present disclosure, and it should be noted that they are not intended to limit the subject matter described in the claims. In other words, the present disclosure is not particularly limited to the embodiments described below and can be implemented with appropriate modifications within the scope of its purpose. For convenience, the present disclosure may be divided into embodiments, etc., in consideration of the explanation of the main points or ease of understanding. However, partial substitution and / or combination of the configurations shown in different embodiments, etc. is possible. In describing such embodiments, duplicated descriptions of substantially identical features may be omitted, and only differences may be described. In particular, similar effects resulting from similar configurations may not be mentioned sequentially in each embodiment.

[0013] The term "cross-sectional view" as used herein refers to the shape of a solid-state battery viewed from a direction substantially perpendicular to the stacking direction (in other words, the shape of a solid-state battery cut along a plane parallel to the thickness direction of the layers). The terms "planar view" and "planar shape" as used herein refer to a sketch of an object viewed from above or below along the thickness direction of the layers (i.e., the stacking direction).

[0014] The terms "upper and lower directions" and "left and right directions" used directly or indirectly in this specification correspond to the upper and lower directions and left and right directions in the drawings, respectively. Unless otherwise specified, the same symbols or signs indicate the same members or parts or the same meanings. In a preferred embodiment, the vertical downward direction (i.e., the direction in which gravity acts) can be considered to correspond to the "downward direction," and the opposite direction to that can be considered to correspond to the "upward direction."

[0015] In the present disclosure, the term "solid-state battery" refers in a broad sense to a battery whose components are made of solids, and in a narrow sense to an all-solid-state battery whose components (particularly preferably all components) are made of solids. In a preferred embodiment, the solid-state battery in the present disclosure is a stacked solid-state battery in which each layer constituting a battery unit is stacked on top of each other, and preferably each such layer is made of a sintered body. A "solid-state battery" is a so-called "secondary battery" that can be repeatedly charged and discharged. The term "secondary battery" should not be overly limited to its name, and can also include, for example, an electricity storage device.

[0016] The features of the present disclosure relate to the electrode layers and terminal electrodes included in the solid-state battery. Below, we will first explain the basic configuration of the solid-state battery of the present disclosure in order to understand the overall structure of the solid-state battery. However, the configuration of the solid-state battery described here is merely an example for understanding the invention and does not limit the invention.

[0017] [Basic Structure of Solid-State Battery] Fig. 1 is a perspective view showing a schematic external appearance of a solid-state battery according to an embodiment of the present disclosure. Fig. 2 is a schematic cross-sectional view of the solid-state battery of Fig. 1 taken along the line A-A in the direction of the arrow. The solid-state battery has at least positive and negative electrode layers and a solid electrolyte. Specifically, as shown in Figs. 1 and 2, the solid-state battery 200 includes a solid-state battery stack 100 including battery structural units each consisting of a positive electrode layer 10A, a negative electrode layer 10B, and a solid electrolyte layer 20 interposed at least therebetween.

[0018] A solid state battery 200 according to the present disclosure typically comprises a solid state battery stack 100 including, along a stacking direction L, at least one battery structural unit made up of a positive electrode layer 10A, a negative electrode layer 10B, and a solid electrolyte layer 20 interposed therebetween; and a positive electrode terminal electrode 40A and a negative electrode terminal electrode 40B provided on opposing side surfaces of the solid state battery stack 100. In the solid state battery stack 100, the positive electrode layers 10A and the negative electrode layers 10B are alternately stacked with the solid electrolyte layer 20 interposed therebetween.

[0019] The layers constituting the solid-state battery 200 may be formed by firing, and the positive electrode layer, negative electrode layer, solid electrolyte layer, etc. may form fired layers. For example, the positive electrode layer, negative electrode layer, and solid electrolyte layer may be fired together, and therefore the solid-state battery stack may form a fired body.

[0020] The positive electrode layer 10A is an electrode layer containing at least a positive electrode active material. The positive electrode layer may further contain a solid electrolyte. In one embodiment, the positive electrode layer 10A is composed of a sintered body containing at least positive electrode active material particles and solid electrolyte particles. On the other hand, the negative electrode layer 10B is an electrode layer containing at least a negative electrode active material. The negative electrode layer 10B may further contain a solid electrolyte. In one embodiment, the negative electrode layer 10B is composed of a sintered body containing at least a negative electrode active material particles and solid electrolyte particles. The positive electrode layer 10A and the negative electrode layer 10B having such a configuration may also be referred to as a "composite positive electrode body" and a "composite negative electrode body," respectively.

[0021] The positive electrode active material and the negative electrode active material are materials involved in the transfer of electrons in a solid-state battery. Charge and discharge are performed by the transfer of electrons through the solid electrolyte, which transfers ions (conduction) between the positive electrode layer and the negative electrode layer. Each electrode layer, particularly the positive electrode layer and the negative electrode layer, is preferably a layer capable of absorbing and releasing lithium ions or sodium ions. In other words, the solid-state battery is preferably an all-solid-state secondary battery in which lithium ions or sodium ions transfer between the positive electrode layer 10A and the negative electrode layer 10B through the solid electrolyte to charge and discharge the battery.

[0022] The positive electrode active material contained in the positive electrode layer 10A may be at least one selected from the group consisting of, for example, a lithium-containing phosphate compound having a Nasicon structure, a lithium-containing phosphate compound having an olivine structure, a lithium-containing layered oxide, and a lithium-containing oxide having a spinel structure.

[0023] An example of a lithium-containing phosphate compound having a Nasicon structure is Li ３ V ２ (P.O. ４ ) ３ Examples of lithium-containing phosphate compounds having an olivine structure include Li ３ Fe ２ (P.O. ４ ) ３ , LiFePO ４ , and / or LiMnPO ４ An example of a lithium-containing layered oxide is LiCoO ２ , and / or LiCo １／３ Ni １／３ Mn １／３ O ２ An example of a lithium-containing oxide having a spinel structure is LiMn ２ O ４ , and / or LiNi ０．５ Mn １．５ O ４The type of lithium compound is not particularly limited, and examples thereof include lithium transition metal composite oxides and lithium transition metal phosphate compounds. Lithium transition metal composite oxides are a general term for oxides containing lithium and one or more transition metal elements as constituent elements. Lithium transition metal phosphate compounds are a general term for phosphate compounds containing lithium and one or more transition metal elements as constituent elements. The type of transition metal element is not particularly limited, and examples thereof include cobalt (Co), nickel (Ni), manganese (Mn), and iron (Fe).

[0024] In addition, the positive electrode active material capable of absorbing and releasing sodium ions may be, for example, at least one selected from the group consisting of a sodium-containing phosphate compound having a Nasicon structure, a sodium-containing phosphate compound having an olivine structure, a sodium-containing layered oxide, and a sodium-containing oxide having a spinel structure. For example, in the case of a sodium-containing phosphate compound, Na ３ V ２ (P.O. ４ ) ３ , NaCoFe ２ (P.O. ４ ) ３ , Na ２ Ni ２ Fe(PO ４ ) ３ , Na ３ Fe ２ (P.O. ４ ) ３ , Na ２ FeP ２ O ７ , Na ４ Fe ３ (P.O. ４ ) ２ (P ２ O ７ ), and NaFeO as a sodium-containing layered oxide ２ At least one selected from the group consisting of:

[0025] Alternatively, the positive electrode active material may be, for example, an oxide, a disulfide, a chalcogenide, or a conductive polymer. The oxide may be, for example, titanium oxide, vanadium oxide, or manganese dioxide. The disulfide may be, for example, titanium disulfide or molybdenum sulfide. The chalcogenide may be, for example, niobium selenide. The conductive polymer may be, for example, a disulfide, polypyrrole, polyaniline, polythiophene, polyparastyrene, polyacetylene, or polyacene.

[0026] (Negative Electrode Active Material) Examples of the negative electrode active material contained in the negative electrode layer 10B include at least one selected from the group consisting of oxides containing at least one element selected from the group consisting of titanium (Ti), silicon (Si), tin (Sn), chromium (Cr), iron (Fe), niobium (Nb), and molybdenum (Mo), carbon materials such as graphite, graphite-lithium compounds, lithium alloys, lithium-containing phosphate compounds having a Nasicon structure, lithium-containing phosphate compounds having an olivine structure, and lithium-containing oxides having a spinel structure. An example of a lithium alloy is Li-Al. An example of a lithium-containing phosphate compound having a Nasicon structure is Li. ３ V ２ (P.O. ４ ) ３ , and / or LiTi ２ (P.O. ４ ) ３ Examples of lithium-containing phosphate compounds having an olivine structure include Li ３ Fe ２ (P.O. ４ ) ３ , and / or LiCuPO ４ Examples of lithium-containing oxides having a spinel structure include Li ４ Ti ５ O １２ etc.

[0027] In addition, examples of negative electrode active materials capable of absorbing and releasing sodium ions include at least one selected from the group consisting of sodium-containing phosphate compounds having a Nasicon structure, sodium-containing phosphate compounds having an olivine structure, and sodium-containing oxides having a spinel structure.

[0028] In the solid-state battery 200, the positive electrode layer 10A and the negative electrode layer 10B may be made of the same material, or may be made of different materials.

[0029] Furthermore, the positive electrode layer 10A and / or the negative electrode layer 10B may contain a sintering aid such as at least one selected from the group consisting of lithium oxide, sodium oxide, potassium oxide, boron oxide, silicon oxide, bismuth oxide, and phosphorus oxide.

[0030] The thickness of the positive electrode layer 10A and the negative electrode layer 10B is not particularly limited, but may be, for example, independently 2 μm or more and 50 μm or less, particularly 5 μm or more and 30 μm or less.

[0031] (Positive Electrode Current Collector Layer / Negative Electrode Current Collector Layer) Although not essential elements of the electrode layers, the positive electrode layer 10A and the negative electrode layer 10B may include a positive electrode current collector layer 11A and a negative electrode current collector layer 11B, respectively. The positive electrode current collector layer 11A and the negative electrode current collector layer 11B may each have the form of a foil. On the other hand, if greater importance is placed on improving electronic conductivity through co-firing, reducing the manufacturing cost of the solid-state battery, and / or reducing the internal resistance of the solid-state battery, the positive electrode current collector layer 11A and the negative electrode current collector layer 11B may each have the form of a sintered body. The positive electrode current collector layer 11A and the negative electrode current collector layer 11B may each have an electrical connection portion for electrical connection to the outside and may be configured to be electrically connectable to a terminal electrode.

[0032] When the positive electrode current collector layer 11A and the negative electrode current collector layer 11B are in the form of a sintered body, they may be composed of a sintered body containing a conductive material and a sintering aid. The sintering aid contained in the positive electrode current collector layer 11A and the negative electrode current collector layer 11B may be selected from, for example, materials similar to the sintering aid that may be contained in the positive electrode layer and / or the negative electrode layer.

[0033] As described above, the positive electrode current collector layer 11A and the negative electrode current collector layer 11B are not essential for the solid-state battery, and a solid-state battery that does not include the positive electrode current collector layer 11A and the negative electrode current collector layer 11B is also conceivable. In other words, the solid-state battery of the present disclosure may be a solid-state battery without current collector layers.

[0034] (Solid Electrolyte Layer) The solid electrolyte layer 20 may be provided at least between the positive electrode layer 10A and the negative electrode layer 10B. That is, the solid electrolyte layer 20 may be present around the positive electrode layer 10A and / or the negative electrode layer 10B so as to protrude from between the positive electrode layer 10A and the negative electrode layer 10B. The solid electrolyte contained in the solid electrolyte layer is a material capable of conducting lithium ions or sodium ions. In particular, the solid electrolyte constituting a battery structural unit in a solid-state battery may form a layer 20 capable of conducting lithium ions between the positive electrode layer and the negative electrode layer. Specific solid electrolytes may be, for example, one or more of a crystalline solid electrolyte, a glass-based solid electrolyte, a glass-ceramic-based solid electrolyte, and the like.

[0035] The crystalline solid electrolyte is, for example, an oxide-based crystalline material, a sulfide-based crystalline material, etc. Examples of the oxide-based crystalline material include a lithium-containing phosphate compound having a Nasicon structure, an oxide having a perovskite structure, an oxide having a garnet-type or garnet-like structure, and an oxide glass ceramic-based lithium ion conductor.

[0036] The lithium-containing phosphate compound having a Nasicon structure includes Li ｘ M ｙ (P.O. ４ ) ３(1≦x≦2, 1≦y≦2, M is at least one selected from the group consisting of titanium (Ti), germanium (Ge), aluminum (Al), gallium (Ga) and zirconium (Zr). An example of a lithium-containing phosphate compound having a Nasicon structure is, for example, Li １．２ Al ０．２ Ti １．８ (P.O. ４ ) ３ Examples of oxides having a perovskite structure include La ０．５５ Li ０．３５ TiO ３ Examples of oxides having a garnet-type or garnet-like structure include Li ７ La ３ Zr ２ O １２ Examples of sulfide-based crystal materials include thio-LISICON, for example, Li ３．２５ Ge ０．２５ P ０．７５ S ４ and Li １０ GeP ２ S １２ The crystalline solid electrolyte may include a polymer material (for example, polyethylene oxide (PEO)).

[0037] Examples of glass-based solid electrolytes include oxide-based glass materials and sulfide-based glass materials. Examples of oxide-based glass materials include 50Li ４ SiO ４ ・50Li ３ BO ３ Examples of sulfide-based glass materials include 30Li ２ S・26B ２ S ３ ・44LiI, 63Li ２ S・36SiS ２ ・1Li ３ P.O. ４ , 57Li ２ S・38SiS ２ ・5Li ４ SiO ４ , 70Li ２ S・30P ２ S５ and 50Li ２ S・50GeS ２ etc.

[0038] The glass ceramic solid electrolyte may be, for example, an oxide-based glass ceramic material or a sulfide-based glass ceramic material. As the oxide-based glass ceramic material, for example, a phosphate compound containing lithium, aluminum, and titanium as constituent elements (LATP) or a phosphate compound containing lithium, aluminum, and germanium as constituent elements (LAGP) may be used. LATP may be, for example, Li １．０７ Al ０．６９ Ti １．４６ (P.O. ４ ) ３ LAGP is, for example, Li １．５ Al ０．５ Ge １．５ (P.O. ４ ) and the like. Examples of sulfide-based glass ceramic materials include Li ７ P ３ S １１ and Li ３．２５ P ０．９５ S ４ etc.

[0039] In addition, examples of solid electrolytes capable of conducting sodium ions include sodium-containing phosphate compounds having a Nasicon structure, oxides having a perovskite structure, and oxides having a garnet or garnet-like structure. Examples of sodium-containing phosphate compounds having a Nasicon structure include Na ｘ M ｙ (P.O. ４ ) ３ (1≦x≦2, 1≦y≦2, M is at least one selected from the group consisting of Ti, Ge, Al, Ga and Zr).

[0040] The solid electrolyte layer 20 may contain a sintering aid. The sintering aid contained in the solid electrolyte layer 20 may be selected from, for example, the same materials as the sintering aids that may be contained in the positive electrode layer 10A and / or the negative electrode layer 10B.

[0041] There are no particular limitations on the thickness of the solid electrolyte layer 20. The thickness of the solid electrolyte layer 20 located between the positive electrode layer 10A and the negative electrode layer 10B may be, for example, 1 μm or more and 15 μm or less, particularly 1 μm or more and 5 μm or less.

[0042] (Terminal Electrodes) The solid-state battery 200 is generally provided with terminal electrodes 40A, 40B. In particular, the terminal electrodes 40A, 40B are provided on the side surfaces of the solid-state battery. More specifically, a positive electrode side terminal electrode 40A connected to the positive electrode layer 10A and a negative electrode side terminal electrode 40B connected to the negative electrode layer 10B are provided (see FIG. 2). Such terminal electrodes 40A, 40B contain a conductive material.

[0043] [Features of the Solid-State Battery of the Present Disclosure] The present inventors have conducted extensive research into solutions for providing a solid-state battery capable of suppressing the occurrence of migration. As a result, they have found that using a carbon-based conductive material as the material for the electrode layer and terminal electrode is effective. In particular, they have focused on the fact that the occurrence of migration in solid-state batteries is largely caused by the ionization and migration of metal materials contained in the positive electrode side to the negative electrode side under high-voltage conditions, and have found that the occurrence of migration can be suppressed by using a carbon-based conductive material in at least the positive electrode layer and the positive electrode terminal electrode. Furthermore, they have newly found that when the content of the carbon-based conductive material contained in the terminal electrode is within a predetermined range, it is possible to provide a solid-state battery that suppresses the occurrence of migration and can function favorably as a solid-state battery.

[0044] In the solid-state battery 200 of the present disclosure, at least the positive electrode layer 10A and the positive electrode terminal electrode 40A electrically connected to the positive electrode layer 10A each contain a carbon-based conductive material. In particular, the content of the carbon-based conductive material in the positive electrode terminal electrode 40A is greater than 30 volume % and less than 95 volume % based on the volume of the positive electrode terminal electrode 40A. Of the positive electrode layer 10A and the negative electrode layer 10B, at least the positive electrode layer 10A contains a carbon-based conductive material, and of the positive electrode terminal electrode 40A and the negative electrode terminal electrode 40B, at least the positive electrode terminal electrode 40A contains a carbon-based conductive material. This suppresses ionization of the metal material in the positive electrode layer 10A and the positive electrode terminal electrode 40A due to application of voltage. This suppresses migration and short circuits caused by migration. Furthermore, by having the content of the carbon-based conductive material in the positive electrode terminal electrode 40A within the above-mentioned range, a solid-state battery that can function properly as a solid-state battery can be obtained while suppressing migration.

[0045] As used herein, "functioning appropriately as a solid-state battery" means that the solid-state battery has sufficient discharge capacity and sufficient mechanical strength to prevent damage during use. For example, if the content of the carbon-based conductive material in the positive terminal electrode 40A is 30% by volume or less, the positive terminal electrode 40A may not have sufficient electronic conductivity, resulting in an excessively low discharge capacity and the battery being unable to function appropriately as a solid-state battery. Furthermore, if the content of the carbon-based conductive material in the positive terminal electrode 40A is 95% by volume or more, the adhesive strength between the terminal electrode and the solid-state battery stack 100, including the electrode layer and the solid electrolyte layer, may be reduced. This may result in the terminal electrode peeling off from the solid-state battery stack 100 during use (e.g., during charging or discharging), raising concerns about structural stability. In the solid-state battery disclosed herein, the content of the carbon-based conductive material in the positive terminal electrode 40A is greater than 30% by volume but less than 95% by volume. By setting the content of the carbon-based conductive material within the above range, the solid battery stack 100 has a sufficient discharge capacity and can be suitably bonded to the terminal electrode 40A, thereby allowing the solid battery of the present disclosure to function suitably as a solid battery while suppressing migration due to the inclusion of the carbon-based conductive material.

[0046] Preferably, the content of the carbon-based conductive material in the positive terminal electrode 40A may be 35% by volume or more, and more preferably 40% by volume or more. When the content of the carbon-based conductive material in the positive terminal electrode 40A is within the above-mentioned range, a solid-state battery that is more suitable in terms of discharge capacity can be provided. Furthermore, the content of the carbon-based conductive material in the positive terminal electrode 40A is more preferably 90% by volume or less. When the content of the carbon-based conductive material in the positive terminal electrode 40A is within the above-mentioned range, a solid-state battery that is more suitable in terms of adhesive strength between the solid battery stack 100 and the terminal electrode 40A can be provided.

[0047] Similarly to the positive terminal electrode 40A, the negative terminal electrode 40B electrically connected to the negative electrode layer 10B may also contain a carbon-based conductive material. The negative terminal electrode 40B may contain the carbon-based conductive material within the same content range as that described above for the positive terminal electrode 40A. In other words, each of the positive terminal electrode 40A and the negative terminal electrode 40B may contain a carbon-based conductive material. This makes it possible to further suppress the occurrence of migration.

[0048] The carbon-based conductive material contained in the terminal electrode may be, for example, at least one of graphite, carbon fiber, carbon black, and carbon nanotubes. Examples of the carbon fiber include vapor-grown carbon fiber (VGCF). Examples of the carbon black include at least one of thermal black, furnace black, channel black, acetylene black, and ketjen black. Examples of the carbon nanotubes include multi-walled carbon nanotubes (MWCNT), such as single-walled carbon nanotubes (SWCNT) and double-walled carbon nanotubes (DWCNT). More preferably, the carbon-based conductive material contained in the terminal electrode may be at least one of graphite and VGCF. This allows for a solid-state battery that can function more effectively as a solid-state battery while suppressing migration.

[0049] When the positive electrode terminal electrode 40A and the negative electrode terminal electrode 40B each contain a carbon-based conductive material, the carbon-based conductive materials contained in the positive electrode terminal electrode 40A and the negative electrode terminal electrode 40B may be the same material or different materials. Furthermore, the content of the carbon-based conductive material in the positive electrode terminal electrode 40A and the negative electrode terminal electrode 40B may be the same content or different contents.

[0050] [First Embodiment] As shown in Figure 2, in a solid-state battery, at least one of the positive electrode layer 10A and the negative electrode layer 10B may include a current collector layer. That is, the electrode layer may include an electrode active material layer and a current collector layer. When the electrode layer includes a current collector layer, at least the current collector layer 11A of the positive electrode layer 10A may include a carbon-based conductive material. In other words, in a solid-state battery, of the positive electrode layer 10A and the negative electrode layer 10B, at least the positive electrode layer 10A may include a current collector layer 11A including a carbon-based conductive material.

[0051] Similarly to the positive electrode layer 10A, the negative electrode layer 10B may also include a current collector layer 11B containing a carbon-based conductive material. That is, each of the positive electrode layer 10A and the negative electrode layer 10B may include a current collector layer containing a carbon-based conductive material. This makes it possible to more effectively suppress the occurrence of migration.

[0052] When a larger discharge capacity and higher structural stability are important, the content of the carbon-based conductive material in the current collector layer may be more than 30% by volume and not more than 90% by volume, and more preferably 40% by volume or more and not more than 90% by volume, based on the volume of the current collector layer. By having the content of the carbon-based conductive material in the current collector layer within the above range, a solid-state battery that can function more suitably as a solid-state battery while suppressing migration can be provided.

[0053] Although not particularly limited, the carbon-based conductive material contained in the current collector layer can be, for example, at least one of graphite, carbon fiber, carbon black, and carbon nanotubes. Examples of carbon fibers that can be used include VGCF. Examples of carbon black include at least one of thermal black, furnace black, channel black, acetylene black, and ketjen black. Examples of carbon nanotubes that can be used include single-wall carbon nanotubes (SWCNTs) and multi-wall carbon nanotubes (MWCNTs) such as double-wall carbon nanotubes (DWCNTs). Considering high conductivity, structural stability as a current collector layer, heat resistance, and ease of handling during manufacturing, graphite is preferred as the carbon-based conductive material contained in the current collector layer. This allows for the production of a solid-state battery that can function more effectively as a solid-state battery while suppressing migration.

[0054] When each of the positive electrode layer 10A and the negative electrode layer 10B includes a current collector layer containing a carbon-based conductive material, the carbon-based conductive material contained in the current collector layer 11A of the positive electrode layer 10A and the current collector layer 11B of the negative electrode layer 10B may be the same material or different materials. Furthermore, the content of the carbon-based conductive material in the current collector layers 11A, 11B of the positive electrode layer 10A and the negative electrode layer 10B may be the same content or different contents.

[0055] The content of the carbon-based conductive material in the electrode layer and terminal electrode can be measured by image analysis combining electron microscope observation and energy dispersive X-ray analysis (EDX). Specifically, a cross section is cut out using an ion milling device or the like, and a cross-sectional image of the current collector layer or terminal electrode is obtained using a scanning electron microscope (SEM) (Model No. SU-8040, manufactured by Hitachi High-Technologies Corporation). EDX mapping is then performed on the obtained cross-sectional image. Next, the area ratio of the carbon-based conductive material in the current collector layer or terminal electrode is calculated by image analysis using image analysis software (e.g., ImageJ). The area ratio of the carbon-based conductive material in the current collector layer or terminal electrode can be considered to be the same as the volume ratio of the carbon-based conductive material in the current collector layer or terminal electrode. In this manner, the content of the carbon-based conductive material can be measured.

[0056] Second Embodiment FIG. 3 is a schematic cross-sectional view showing a solid-state battery 201 according to a second embodiment of the present disclosure. As shown in the figure, in the solid-state battery 201 according to the second embodiment, at least one of the positive electrode layer 10A and the negative electrode layer 10B is a "collector-less" battery that does not include a current collector or current collector layer (which may also be simply referred to as a "collector-less solid-state battery," a "collector-less battery," or a "collector-layer-less solid-state battery"). Because the solid-state battery 201 according to the second embodiment of the present disclosure is "collector-less," it does not include a current collector or current collector layer that is in direct contact with the electrode layer in the solid-state battery stack 100, nor does it include a current collector or current collector layer that extends inside the electrode layer. In this way, the battery according to the present disclosure, particularly the solid-state battery stack 100, may have a current-collector-less structure or a current-collector-layer-less structure.

[0057] The current collector / current collecting layer not provided in the structure intended by the expression "collector-less" refers to an "active material-free conductive layer (e.g., a sintered body layer formed from a conductive agent and a sintering aid)" that is provided separately from an "active material-containing layer" from the viewpoint of reducing internal resistance, etc. Therefore, the solid state battery of this embodiment does not include an "active material-free conductive layer" (particularly, an "active material-free conductive layer" that is provided in contact with an "active material-containing layer" or inside such an active material-containing layer) that is provided solely for the purpose of reducing internal resistance.

[0058] In the solid-state battery 201 of the second embodiment, of the positive electrode layer 10A and the negative electrode layer 10B, at least the positive electrode layer 10A is a current collector-less electrode layer (hereinafter also referred to as a "current collector-less electrode layer"). The current collector-less electrode layer may contain a carbon-based conductive material. This means that the current collector-less electrode layer contains at least an electrode active material and a carbon-based conductive material as a conductive additive. In other words, the electrode active material and the carbon-based conductive material as a conductive additive may be mixed within the electrode layer. The current collector-less electrode layer may further contain auxiliary components such as a solid electrolyte and / or a sintering additive.

[0059] Similarly to the positive electrode layer 10A, the negative electrode layer 10B may also be a collector-less electrode layer containing a carbon-based conductive material. That is, each of the positive electrode layer 10A and the negative electrode layer 10B may be a collector-less electrode layer containing a carbon-based conductive material as a conductive additive. This makes it possible to further suppress the occurrence of migration.

[0060] When a larger discharge capacity and higher structural stability are important, the content of the carbonaceous conductive material in the current collector-less electrode layer may be greater than 1 vol % and less than 20 vol %, and more preferably 3 vol % or more and 15 vol % or less, based on the volume of the current collector-less electrode layer. By having the content of the carbonaceous conductive material in the current collector layer within the above range, a solid-state battery that can function more suitably as a solid-state battery while suppressing migration can be provided.

[0061] The carbon-based conductive material contained in the collector-less electrode layer can be, for example, at least one of graphite, carbon fiber, carbon black, and carbon nanotubes. Examples of carbon fibers that can be used include VGCF. Examples of carbon blacks that can be used include, for example, at least one of thermal black, furnace black, channel black, acetylene black, and ketjen black. Examples of carbon nanotubes that can be used include, for example, single-wall carbon nanotubes (SWCNT), double-wall carbon nanotubes (DWCNT), and other multi-wall carbon nanotubes (MWCNT). Considering the discharge capacity of the solid-state battery, structural stability as a collector-less electrode layer, and ease of handling during manufacturing, it is preferable that the carbon-based conductive material contained in the collector-less electrode layer be VGCF. This allows for a solid-state battery that can function more effectively as a solid-state battery while suppressing migration.

[0062] When the positive electrode layer 10A and the negative electrode layer 10B are each a collector-less electrode layer containing a carbon-based conductive material, the carbon-based conductive materials contained in the positive electrode layer 10A and the negative electrode layer 10B may be the same or different from each other. Furthermore, the content of the carbon-based conductive material in the positive electrode layer 10A and the negative electrode layer 10B may be the same or different from each other.

[0063] The terminal electrode, current collector layer, and current collector-less electrode layer containing the above-described carbon-based conductive material may be substantially free of metal materials from the group consisting of Ag, Ni, Cu, Sn, Zn, and Al. These metal materials can ionize due to electrolytic corrosion or the like, causing migration. The solid-state battery of the present disclosure is substantially free of these metal materials and contains a carbon-based conductive material, thereby effectively suppressing the occurrence of migration. Note that, in this specification, "substantially free" means that the presence of trace amounts of components that may be unavoidably or accidentally mixed in during the formation of the electrode layer is acceptable. For example, it is acceptable for such unavoidable or accidental components to be present in a total amount of 5 wt % or less, preferably 2 wt % or less, and more preferably 1 wt % or less, based on the volume of each of the terminal electrode, current collector layer, and / or current collector-less electrode layer.

[0064] [Method for manufacturing solid-state battery] The solid-state battery of the present disclosure can be manufactured by a printing method such as a screen printing method, a green sheet method using a green sheet, or a combination of these methods. Hereinafter, for the purpose of understanding the present disclosure, cases where the printing method and the green sheet method are adopted will be described in detail, but the present disclosure is not limited to these methods.

[0065] (Solid state battery laminate precursor formation process) In this process, several types of pastes are used as inks, such as a positive electrode paste, a negative electrode paste, a paste for a solid electrolyte layer, a current collector paste, and a paste for an insulating layer, etc. That is, the pastes are applied by a printing method to form pastes of a predetermined structure on a support substrate.

[0066] In printing, a solid state battery laminate precursor corresponding to a predetermined solid state battery structure can be formed on a substrate by sequentially stacking printed layers with a predetermined thickness and pattern shape. The type of pattern formation method is not particularly limited as long as it is a method that can form a predetermined pattern, and may be selected from, for example, a screen printing method, a gravure printing method, etc.

[0067] The paste can be prepared by wet mixing predetermined constituent materials for each layer, selected from the group consisting of a positive electrode active material, a negative electrode active material, a conductive material, a solid electrolyte, an insulating material, a binder, and a sintering aid, with an organic vehicle in which an organic material is dissolved in a solvent. The positive electrode paste may contain, for example, a positive electrode active material, a conductive material, a solid electrolyte, a binder, a sintering aid, an organic material, and a solvent. The negative electrode paste may contain, for example, a negative electrode active material, a conductive material, a solid electrolyte, a binder, a sintering aid, an organic material, and a solvent. The solid electrolyte layer paste may contain, for example, a solid electrolyte, a binder, a sintering aid, an organic material, and a solvent. The positive electrode current collector paste and the negative electrode current collector paste may contain a conductive material, an active material, a solid electrolyte, a binder, a sintering aid, an organic material, and a solvent. Of these, at least the conductive material contained in the positive electrode current collector paste is a carbon-based conductive material. Alternatively, the conductive materials contained in the positive electrode current collector paste and the negative electrode current collector paste may each be a carbon-based conductive material. Furthermore, for example, when the positive electrode layer and / or the negative electrode layer are configured as collector-less electrode layers, the conductive materials contained in the positive electrode paste and / or the negative electrode paste that form the collector-less electrode layers can be a carbon-based conductive material.

[0068] The insulating layer paste may contain, for example, an insulating material containing a heat-resistant resin (imide-based resin and / or imidazole-based resin), a binder, a sintering aid, an organic material, and a solvent.

[0069] The organic material contained in the paste is not particularly limited, but can be at least one polymer material selected from the group consisting of polyvinyl acetal resin, cellulose resin, polyacrylic resin, polyurethane resin, polyvinyl acetate resin, polyvinyl alcohol resin, etc. The type of solvent is not particularly limited, but can be, for example, one or more organic solvents such as butyl acetate, N-methyl-pyrrolidone, toluene, terpineol, and N-methyl-pyrrolidone.

[0070] In the wet mixing, media can be used, specifically, a ball mill method, a viscomill method, etc. Alternatively, a wet mixing method without using media can be used, such as a sand mill method, a high-pressure homogenizer method, or a kneader dispersion method.

[0071] The support substrate is not particularly limited as long as it is a support capable of supporting each paste layer, and may be, for example, a release film with a release treatment applied to one surface. Specifically, a substrate made of a polymer material such as polyethylene terephthalate can be used. When each paste layer is subjected to the firing step while being held on the substrate, a substrate that is heat resistant to the firing temperature may be used.

[0072] The applied paste is dried on a heated hot plate to form a positive electrode layer green sheet, a negative electrode layer green sheet, a solid electrolyte layer green sheet, an electrode separation green sheet, and / or a protective layer green sheet, each having a predetermined shape and thickness, on a substrate (e.g., a PET film).

[0073] Next, each green sheet is peeled off from the substrate. After peeling, the green sheets of each component of one battery unit are stacked in order along the stacking direction to form a solid battery stack precursor. After stacking, a solid electrolyte layer, an electrode separator, and / or a protective layer may be provided on the side regions of the electrode green sheets by screen printing.

[0074] (Firing step) In the firing step, the solid battery laminate precursor is subjected to firing. By way of example only, firing is performed by heating in a nitrogen gas atmosphere containing oxygen gas or in the air. Firing may be performed while applying pressure to the solid battery laminate precursor in the stacking direction (and in some cases, in the stacking direction and a direction perpendicular to the stacking direction).

[0075] Through such firing, a solid state battery stack is formed, and ultimately a desired solid state battery is obtained.

[0076] (Process for Forming Terminal Electrodes) The terminal electrodes can be formed by applying a terminal electrode paste containing a conductive material to the exposed positive and negative electrode sides of the battery element. It is preferable to provide the positive and negative terminal electrodes so that they extend to the underside of the battery element, since this allows them to be connected to the mounting lands with a small area during surface mounting of the solid-state battery. After applying the terminal electrode paste made of the conductive material, the terminal electrodes are fired. This allows the solid-state battery of the present disclosure to be manufactured.

[0077] Alternatively, the terminal electrodes may be manufactured by resin curing without firing. Specifically, a resin-curing conductive paste is used as the terminal electrode paste, and the terminal electrode paste is applied to the exposed positive and negative electrode sides of the battery element. Then, the resin material is cured by heat curing, light curing (UV curing), or the like, to manufacture a solid-state battery equipped with terminal electrodes. In the terminal electrodes of the solid-state battery obtained in this manner, the composition of the materials contained in the terminal electrodes does not substantially change during the manufacturing process. In other words, the volume ratio of the conductive material used in the manufacturing process in the terminal electrodes can be considered to be the same as the volume ratio of the conductive material in the terminal electrodes of the resulting solid-state battery.

[0078] The embodiment of the present disclosure as described above includes the following preferred aspects. First Aspect: A solid state battery comprising a positive electrode layer, a negative electrode layer, a solid electrolyte layer, a positive electrode terminal electrode electrically connected to the positive electrode layer, and a negative electrode terminal electrode electrically connected to the negative electrode layer, wherein at least the positive electrode layer and the positive electrode terminal electrode each contain a carbon-based conductive material, and the content of the carbon-based conductive material in the positive electrode terminal electrode is greater than 30% by volume and less than 95% by volume. Second Aspect: The solid state battery of the first aspect, wherein the content of the carbon-based conductive material in the positive electrode terminal electrode is 40% by volume or more and 90% by volume or less. Third Aspect: The solid state battery of the first or second aspect, wherein the carbon-based conductive material contained in the positive electrode terminal electrode is at least one of graphite and carbon black. Fourth Aspect: The solid state battery of any of the first to third aspects, wherein the positive electrode layer, the negative electrode layer, the positive electrode terminal electrode, and the negative electrode terminal electrode each contain a carbon-based conductive material. Fifth Aspect: A solid state battery in any of the first to fourth aspects, wherein, of the positive electrode layer and the negative electrode layer, at least the positive electrode layer comprises a current collector layer, the current collector layer contains the carbon-based conductive material, and the content of the carbon-based conductive material in the current collector layer is more than 30 vol% and not more than 90 vol%. Sixth Aspect: A solid state battery in the fifth aspect, wherein the content of the carbon-based conductive material in the current collector layer is 40 vol% or more and 90 vol% or less. Seventh Aspect: A solid state battery in the fifth or sixth aspect, wherein the carbon-based conductive material contained in the current collector layer is graphite. Eighth Aspect: A solid state battery in any of the first to fourth aspects, wherein, of the positive electrode layer and the negative electrode layer, at least the positive electrode layer is a current collector-less electrode layer not comprising a current collector layer, and the content of the carbon-based conductive material in the current collector-less electrode layer is more than 1 vol% and not more than 15 vol%. Ninth aspect: The solid state battery of the eighth aspect, wherein the content of the carbon-based conductive material in the collector-less electrode layer is 3% by volume or more and 15% by volume or less. Tenth aspect: The solid state battery of the eighth or ninth aspect, wherein the carbon-based conductive material contained in the collector-less electrode layer is VGCF.Eleventh Aspect: In any one of the first to tenth aspects, the solid-state battery is characterized in that at least the positive electrode layer and the positive electrode terminal electrode do not contain Ag, Ni, Cu, Zn, Sn, or Al.

[0079] A demonstration test was carried out in accordance with the present disclosure. The solid-state battery structure shown in FIGS. 2 and 3 was adopted.

[0080] Example 1 A solid-state battery of Example 1 was manufactured according to the above-described method for manufacturing a solid-state battery. The terminal electrodes were fabricated by resin curing. Specifically, the solid-state battery was manufactured using a positive electrode paste containing lithium cobalt oxide, a negative electrode paste containing lithium titanate, a positive electrode current collector paste and a negative electrode current collector paste containing a predetermined amount of graphite (SFG15, manufactured by Imerys), and a positive electrode terminal electrode paste and a negative electrode terminal electrode paste containing a thermosetting resin (phenolic resin), graphite (JB-10, manufactured by Nippon Graphite Co., Ltd.), and carbon black (Ketjenblack EC300J, manufactured by Lion Specialty Chemicals).

[0081] Comparative Example 1 A solid-state battery was produced in the same manner as in Example 1, except that silver (SF-KS, manufactured by Mitsui Mining & Smelting Co., Ltd.) was used instead of graphite in the positive electrode current collector paste and the negative electrode current collector paste.

[0082] Comparative Example 2 A solid-state battery was produced in the same manner as in Example 1, except that silver (SF-KS, manufactured by Mitsui Mining & Smelting Co., Ltd.) was used instead of graphite and carbon black in the positive electrode terminal paste and negative electrode terminal paste.

[0083] Examples 2 to 4 Solid-state batteries were manufactured in the same manner as in Example 1, except that the graphite contents in the positive electrode current collector paste and the negative electrode current collector paste were changed.

[0084] Examples 5 and 6 and Comparative Examples 3 and 4 Solid state batteries were manufactured in the same manner as in Example 1, except that the total content of graphite and carbon black in the positive electrode terminal paste and the negative electrode terminal paste was changed.

[0085] Example 7 A solid-state battery was produced in the same manner as in Example 1, except that silver (SF-KS, manufactured by Mitsui Mining & Smelting Co., Ltd.) was used in place of graphite in the negative electrode current collector paste.

[0086] Example 8 A solid-state battery was manufactured using the current collector-less structure shown in Fig. 3. Specifically, the solid-state battery was manufactured using a positive electrode paste containing lithium cobalt oxide and VGCF (VGCF-H, manufactured by Resonac), a negative electrode paste containing lithium titanate and VGCF (VGCF-H, manufactured by Resonac), and a positive electrode terminal electrode paste and a negative electrode terminal electrode paste containing a thermosetting resin (phenolic resin), graphite (JB-10, manufactured by Nippon Graphite Co., Ltd.), and carbon black (Ketjenblack EC300J, manufactured by Lion Specialty Chemicals).

[0087] Examples 9 and 10 Solid-state batteries were produced in the same manner as in Example 8, except that the VGCF contents in the positive electrode paste and the negative electrode paste were changed.

[0088] Example 11 A solid-state battery was produced in the same manner as in Example 8, except that silver (SF-KS, manufactured by Mitsui Mining & Smelting Co., Ltd.) was used instead of VGCF in the negative electrode paste.

[0089] (Evaluation of Battery Characteristics) The battery cells manufactured as described above were charged and discharged under the conditions of a charge voltage of 2.5 V, a charge rate of 0.1 C, a discharge voltage of 0.5 V, and a discharge rate of 0.1 C. Battery cells that obtained a discharge capacity of 90% or more of the theoretical discharge capacity were evaluated as good (A), battery cells that obtained a discharge capacity of 50% or more but less than 90% of the theoretical discharge capacity were evaluated as fair (B), and battery cells that obtained a discharge capacity of less than 50% of the theoretical discharge capacity were evaluated as poor (C).

[0090] (Evaluation of reliability (migration resistance and structural stability)) A charge / discharge cycle test was carried out on the battery element manufactured in the above configuration in a thermostatic chamber at 105°C under the conditions of a charge voltage of 2.5 V, a charge rate of 0.3 C, a discharge voltage of 0.5 V, and a discharge rate of 1 C. If migration occurred during the three-month test and / or if normal charge / discharge was not possible due to peeling of the terminal electrodes, the battery was judged as defective (C). Regarding migration, if the charge voltage did not reach 2.5 V after 20 hours had elapsed, it was judged that migration had occurred.

[0091] As an overall evaluation, if both the above-mentioned evaluation results of the battery characteristics and reliability were good (A), it was designated as the best product (AA); if one was good (A) and the other was fair (B), it was designated as a good product (AB); if both were fair (B), it was designated as a passable product (BB); and if either or both were bad (C), it was designated as a defective product (CC). The best product (AA), fair product (AB), and fair product (BB) were deemed to have passed, and the defective product (CC) was deemed to have failed.

[0092] Table 1 shows the evaluation results of the solid state batteries of Examples 1 to 11 and Comparative Examples 1 to 4. The "conductive material ratio" shown in the table corresponds to the volume ratio of the carbon-based conductive material in the electrode layer or terminal electrode of the manufactured solid state battery.

[0093]

[0094] According to the above results, in Comparative Examples 1 and 2, in which silver was contained in either the positive electrode layer or the terminal electrode, migration was confirmed to occur from the positive electrode layer or terminal electrode containing silver. On the other hand, in Examples 1 to 11 and Comparative Example 4, in which a carbon-based conductive material was contained in at least the positive electrode layer and the positive terminal electrode, migration was not confirmed to occur. These results demonstrate that the use of a carbon-based conductive material improves migration resistance.

[0095] On the other hand, in Comparative Example 3, in which the content of the carbon-based conductive material in the terminal electrode was 95% by volume, peeling of the terminal electrode from the solid battery laminate occurred during testing. Furthermore, in Comparative Example 4, in which the content of the carbon-based conductive material in the terminal electrode was 30% by volume, an excessively small discharge capacity was obtained. On the other hand, it was confirmed that Examples 1 to 11, in which the content of the carbon-based conductive material in the terminal electrode was greater than 30% by volume and less than 95% by volume, also showed good results in terms of discharge capacity. From the above, it was found that the present disclosure provides a solid-state battery that can suppress the occurrence of migration and function favorably as a solid-state battery.

[0096] Furthermore, Examples 1 to 3 and 5 to 6, in which the content of the carbonaceous conductive material in the current collector layer was greater than 30% by volume, exhibited higher discharge capacities than Example 4, in which the content was 30% by volume or less. Furthermore, Examples 8 and 9, in which the content of the carbonaceous conductive material in the current collector-less electrode layer was greater than 1% by volume, exhibited higher discharge capacities than Example 10, in which the content was 1% by volume or less.

[0097] Although the embodiments of the present disclosure have been described above, they are merely typical examples. Therefore, the present disclosure is not limited to these, and it will be readily understood by those skilled in the art that various modifications are possible within the scope of the present disclosure.

[0098] The solid-state battery of the present disclosure can be used in various fields where power storage is expected. By way of example only, the solid-state battery of the present disclosure can be used in the electrical, information, and communications fields where mobile devices and the like are used (for example, the electrical and electronic device fields or the mobile device fields, including small electronic devices such as mobile phones, smartphones, laptops, digital cameras, activity monitors, arm computers, electronic paper, RFID tags, card-type electronic money, and smart watches), household and small industrial applications (for example, power tools, golf carts, and household, nursing care, and industrial robots), large industrial applications (for example, forklifts, elevators, and port cranes), transportation systems (for example, hybrid cars, electric cars, buses, trains, electrically assisted bicycles, and electric motorcycles), power system applications (for example, various power generation systems, road conditioners, smart grids, and general household power storage systems), medical applications (medical devices such as earphones and hearing aids), pharmaceutical applications (dose management systems), IoT, and space and deep-sea applications (for example, space probes and submersible research vessels).

[0099] 10A: Positive electrode layer 10B: Negative electrode layer 11A: Positive electrode current collector layer 11B: Negative electrode current collector layer 12A: Positive electrode active material layer 12B: Negative electrode active material layer 20: Solid electrolyte layer 40A: Positive electrode terminal electrode 40B: Negative electrode terminal electrode 60: Outer layer material 100: Solid battery laminate 200: Solid battery

Claims

1. A solid-state battery comprising a positive electrode layer, a negative electrode layer, a solid electrolyte layer, a positive electrode terminal electrode electrically connected to the positive electrode layer, and a negative electrode terminal electrode electrically connected to the negative electrode layer, wherein at least the positive electrode layer and the positive electrode terminal electrode each contain a carbon-based conductive material, and the content of the carbon-based conductive material in the positive electrode terminal electrode is greater than 30% by volume and less than 95% by volume.

2. The solid state battery according to claim 1, wherein the content of the carbonaceous conductive material in the positive terminal electrode is 40% by volume or more and 90% by volume or less.

3. The solid-state battery according to claim 1 or 2, wherein the carbon-based conductive material contained in the positive terminal electrode is at least one of graphite and carbon black.

4. The solid-state battery according to any one of claims 1 to 3, wherein each of the positive electrode layer, the negative electrode layer, the positive electrode terminal electrode, and the negative electrode terminal electrode contains a carbon-based conductive material.

5. The solid state battery according to any one of claims 1 to 4, wherein of the positive electrode layer and the negative electrode layer, at least the positive electrode layer has a current collector layer, the current collector layer contains the carbon-based conductive material, and the content of the carbon-based conductive material in the current collector layer is greater than 30% by volume and not more than 90% by volume.

6. The solid state battery according to claim 5, wherein the content of said carbonaceous conductive material in said current collector layer is 40% by volume or more and 90% by volume or less.

7. The solid state battery according to claim 5 or 6, wherein the carbon-based conductive material contained in the current collector layer is graphite.

8. The solid-state battery according to any one of claims 1 to 4, wherein of the positive electrode layer and the negative electrode layer, at least the positive electrode layer is a collector-less electrode layer that does not include a collector layer, and the content of the carbon-based conductive material in the collector-less electrode layer is greater than 1 vol % and not more than 15 vol %.

9. The solid state battery according to claim 8, wherein the content of said carbonaceous conductive material in said collector-less electrode layer is 3% by volume or more and 15% by volume or less.

10. The solid-state battery according to claim 8 or 9, wherein the carbon-based conductive material contained in the current collector-less electrode layer is VGCF.

11. The solid-state battery according to any one of claims 1 to 10, wherein at least the positive electrode layer and the positive terminal electrode do not contain Ag, Ni, Cu, Zn, Sn, or Al.

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