Solid-state battery

Abstract

In one embodiment of the present invention, provided is a solid-state battery provided with a negative electrode layer containing a negative electrode active material containing a Li composite oxide and an oxide glass-based solid electrolyte, the amount of the negative electrode active material in the negative electrode layer being less than or equal to the total amount of the negative electrode active material and the solid electrolyte, and the amount of the solid electrolyte in the negative electrode layer being less than or equal to the total amount of the negative electrode active material and the solid electrolyte. The content of the solid electrolyte is from 20% by mass to 60% by mass (inclusive), and the ratio B / A of the actual density B of the negative electrode active material to the true density A of the negative electrode active material is from 0.3 to 0.6 (inclusive).

Description

Technical Field

[0001] This invention relates to a solid-state battery. Background Technology

[0002] Rechargeable batteries have historically been used for various purposes. For example, they are used as power sources for electronic devices such as smartphones and laptops.

[0003] In secondary batteries, liquid electrolytes are generally used as the medium for ion movement that facilitates charging and discharging. That is, the so-called electrolyte is used in secondary batteries. However, in such secondary batteries, safety is generally required in terms of preventing electrolyte leakage. Furthermore, organic solvents used in the electrolyte are flammable substances, so safety is also required in this regard. Therefore, solid-state batteries that use solid electrolytes instead of liquid electrolytes have been studied.

[0004] A solid-state battery is composed of battery elements, which include a positive electrode layer, a negative electrode layer, and a solid electrolyte layer between the positive and negative electrode layers. The positive electrode layer contains a positive electrode active material and a solid electrolyte, and the negative electrode layer contains a negative electrode active material and a solid electrolyte.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2015-144061

[0008] Patent Document 2: Japanese Patent Application Publication No. 2019-77573

[0009] Patent Document 3: Japanese Patent Application Publication No. 2020-068188 Summary of the Invention

[0010] The technical problem that the invention aims to solve

[0011] The inventors of this application have made a new discovery regarding aspects of conventional solid-state batteries that can be improved, and therefore, countermeasures are necessary to address these aspects.

[0012] Specifically, in solid-state batteries, the electrode layer, particularly the negative electrode layer, which is a key component, is sometimes composed of a negative electrode active material containing Li composite oxides and a garnet-type oxide-based solid electrolyte. However, garnet-type oxide-based solid electrolytes are difficult to form a dense interface with the particles of the negative electrode active material, making it difficult to reduce the porosity within the electrode. This results in a higher interfacial resistance between the active material and the solid electrolyte within the negative electrode, making it difficult for lithium ions to move across this interface. Consequently, the volumetric energy density of the solid-state battery may not be able to be improved.

[0013] The present invention was made in view of the above-mentioned technical problems. That is, the object of the present invention is to provide a solid-state battery having a negative electrode layer capable of reducing the interfacial resistance between the active material and the solid electrolyte.

[0014] Technical solutions for solving technical problems

[0015] To achieve the above objectives, in one embodiment of the present invention, a solid-state battery is provided.

[0016] The solid-state battery has a negative electrode layer, which comprises a negative electrode active material containing a Li composite oxide and an oxide glass-based solid electrolyte.

[0017] In the negative electrode layer, the content of the solid electrolyte is 20% by mass or more and 60% by mass or less, relative to the total amount of the negative electrode active material and the solid electrolyte.

[0018] The ratio of the actual density B of the negative electrode active material to the true density A of the negative electrode active material, B / A, is greater than 0.3 and less than 0.6.

[0019] Invention Effects

[0020] According to one embodiment of the present invention, a solid-state battery can provide a negative electrode layer that can reduce the interfacial resistance between the active material and the solid electrolyte. Attached Figure Description

[0021] Figure 1 This is a schematic perspective view of a solid-state battery according to one embodiment of the present invention.

[0022] Figure 2 Observe in the direction of the arrow Figure 1 A schematic cross-sectional view of the solid-state battery at section AA. Detailed Implementation

[0023] The solid-state battery of the present invention will now be described in detail. Although the description is based on the accompanying drawings as needed, the illustrations are merely schematic and illustrative for the purpose of understanding the invention, and the appearance, size ratio, etc., may differ from the actual product.

[0024] The term "cross-sectional view" as used in this specification refers to a shape captured from a direction approximately perpendicular to the stacking direction in the solid-state battery's stacked structure (simply put, a shape taken from a plane parallel to the thickness direction of the layers). Furthermore, the terms "top view" or "top view shape" used in this specification are schematic diagrams based on viewing the object from above or below along the thickness direction of the aforementioned layers (i.e., the aforementioned stacking direction).

[0025] The terms "up and down" and "left and right" used directly or indirectly in this specification correspond to the up and down and left and right directions in the figures, respectively. Unless otherwise specified, the same reference numerals or symbols denote the same components / parts or have the same meaning. In a preferred embodiment, the vertical direction downward (i.e., the direction of gravity) can be considered equivalent to the "downward direction," and its opposite direction to the "upward direction."

[0026] In this invention, "solid-state battery" broadly refers to a battery whose constituent elements are made of solids, and narrowly refers to an all-solid-state battery whose constituent elements (particularly preferably all constituent elements) are made of solids. In a preferred embodiment, the solid-state battery of this invention is a stacked solid-state battery in which the layers constituting the battery constituent units are stacked on top of each other, preferably such layers are made of sintered bodies. A "solid-state battery" is a so-called "secondary battery" capable of repeated charging and discharging. The term "secondary battery" is not overly limited to this name; for example, it may also include energy storage devices.

[0027] The present invention relates to a positive electrode layer included in a solid-state battery. Hereinafter, in order to understand the overall structure of the solid-state battery, the basic structure of the solid-state battery of the present invention will be described. However, the structure of the solid-state battery described herein is merely an example for understanding the invention and is not intended to limit the invention.

[0028] [Basic Structure of Solid-State Batteries]

[0029] Figure 1 This is a schematic perspective view of a solid-state battery according to one embodiment of the present invention. Figure 2 Observe in the direction of the arrow Figure 1 A schematic cross-sectional view of a solid-state battery at section AA. A solid-state battery has at least positive / negative electrode layers and a solid electrolyte. Specifically, as... Figure 1 as well as Figure 2 As shown, the solid-state battery 200 includes a solid-state battery stack 100, which is a battery unit consisting of a positive electrode layer 10A, a negative electrode layer 10B, and at least a solid electrolyte layer 20 between them.

[0030] The solid-state battery 200 of the present invention comprises: a solid-state battery stack 100, having at least one battery unit along the stacking direction L consisting of a positive electrode layer 10A, a negative electrode layer 10B, and a solid electrolyte layer 20 therebetween; and

[0031] The positive terminal 40A and the negative terminal 40B are respectively disposed on opposite sides of the solid-state battery stack 100.

[0032] In the solid battery stack 100, the positive electrode layer 10A and the negative electrode layer 10B are alternately stacked with a solid electrolyte layer 20 in between.

[0033] In a solid-state battery, the various layers can be formed by firing, and the positive electrode layer, negative electrode layer, and solid electrolyte layer can also be formed as fired layers. Preferably, the positive electrode layer, negative electrode layer, and solid electrolyte layer are fired integrally with each other, and the solid-state battery stack is preferably formed as a single fired body.

[0034] The positive electrode layer is an electrode layer that contains at least a positive electrode active material. The positive electrode layer may also contain a solid electrolyte. In a preferred embodiment, the positive electrode layer is composed of a sintered body containing at least positive electrode active material particles and solid electrolyte particles. Conversely, the negative electrode layer is an electrode layer that contains at least a negative electrode active material. The negative electrode layer may also contain a solid electrolyte. In a preferred embodiment, the negative electrode layer is composed of a sintered body containing at least negative electrode active material particles and solid electrolyte particles. A positive electrode layer having such a configuration can be referred to as a "composite positive electrode," and similarly, a negative electrode layer can be referred to as a "composite negative electrode."

[0035] Positive and negative electrode active materials are substances that participate in electron exchange in a solid-state battery. Ions move (conduct) between the positive and negative electrode layers via the solid electrolyte, exchanging electrons and thus charging and discharging. Each electrode layer of the positive and negative electrode layers is particularly preferably a layer capable of intercalating or deintercalating lithium ions or sodium ions. That is, the solid-state battery is preferably an all-solid-state secondary battery in which lithium ions or sodium ions move between the positive and negative electrode layers via the solid electrolyte for charging and discharging.

[0036] Examples of positive electrode active materials included in the positive electrode layer include lithium-containing layered oxides and lithium-containing oxides with spinel-type structures. Examples of lithium-containing layered oxides include LiCoO2 and LiCo. 1 / 3Ni 1 / 3 Mn 1 / 3 O2, etc. Examples of lithium-containing oxides with a spinel-type structure include LiMn2O4 and LiNi. 0.5 Mn 1.5 O4, etc.

[0037] Furthermore, as a positive electrode active material capable of inserting and deinserting sodium ions, it can be selected from sodium-containing layered oxides, sodium-containing oxides with spinel-type structures, etc.

[0038] The positive and / or negative electrode layers may also contain conductive materials. Examples of conductive materials contained in the positive and negative electrode layers include metallic materials such as silver, palladium, gold, platinum, aluminum, copper, and nickel, as well as at least one material composed of carbon.

[0039] Furthermore, the positive electrode layer and / or negative electrode layer may also contain sintering aids. As sintering aids, at least one may be selected from the group consisting of lithium oxide, sodium oxide, potassium oxide, boron oxide, silicon oxide, bismuth oxide, and phosphorus oxide.

[0040] There is no particular limitation on the thickness of the positive electrode layer and the negative electrode layer. For example, they can each be 2μm or more and 50μm or less, especially 5μm or more and 30μm or less.

[0041] (Positive electrode current collector layer / Negative electrode current collector layer)

[0042] Although not a necessary element of the electrode layer, the positive and negative electrode layers can also have a positive current collector layer 11A and a negative current collector layer 11B, respectively. The positive and negative current collector layers can also be distributed in a foil form. However, if more emphasis is placed on the improved electronic conductivity, reduced manufacturing cost of solid-state batteries, and / or reduced internal resistance of solid-state batteries based on integral firing, the positive and negative current collector layers can also have a fired body form.

[0043] The positive current collector constituting the positive current collector layer and the negative current collector constituting the negative current collector layer are preferably made of materials with high conductivity, such as silver, palladium, gold, platinum, aluminum, copper, and / or nickel. The positive and negative current collectors may each have an electrical connection portion for external electrical connection, or they may be configured to be electrically connected to a terminal.

[0044] Alternatively, when the positive and negative current collector layers have a sintered body shape, they can also be composed of a sintered body containing a conductive material and a sintering aid. The conductive material contained in the positive and negative current collector layers can, for example, be selected from the same materials that can be contained in the positive and negative electrode layers. The sintering aid contained in the positive and negative current collector layers can, for example, be selected from the same materials that can be contained in the positive / negative electrode layers.

[0045] (Solid electrolyte)

[0046] Solid electrolytes are materials capable of conducting lithium ions or sodium ions. This solid electrolyte can form a lithium-ion-conducting layer between the positive and negative electrode layers. Alternatively, the solid electrolyte can be contained within both the positive and negative electrode layers.

[0047] The solid electrolyte layer may also contain sintering aids. The sintering aids contained in the solid electrolyte layer may be selected from the same materials as those that may be contained in the positive / negative electrode layer.

[0048] There is no particular limitation on the thickness of the solid electrolyte layer. The thickness of the solid electrolyte layer located between the positive electrode layer and the negative electrode layer can be, for example, more than 1 μm and less than 15 μm, and particularly more than 1 μm and less than 5 μm.

[0049] (Electrode separation section)

[0050] The solid-state battery 200 of the present invention may also have an electrode separation section (also referred to as a "blank layer" or "blank section") 30 (30A, 30B).

[0051] Electrode separation section 30A (positive electrode separation section) is disposed around the positive electrode layer 10A, thereby separating the positive electrode layer 10A from the negative electrode terminal 40B. Electrode separation section 30B (negative electrode separation section) is disposed around the negative electrode layer 10B, thereby separating the negative electrode layer 10B from the positive electrode terminal 40A. Although not particularly limited, the electrode separation section 30 may, for example, be made of one or more materials selected from the group consisting of solid electrolytes, insulating materials, and mixtures thereof.

[0052] The solid electrolyte that can form the electrode separation section 30 can be made of the same material as the solid electrolyte that can form the solid electrolyte layer.

[0053] The insulating material constituting the electrode separation section 30 can also be a non-conductive material, meaning it is not electrically conductive. While not particularly limited, the insulating material can be, for example, glass or ceramic. Glass can be selected as the insulating material. While not particularly limited, the glass material can be at least one selected from the group consisting of soda-lime glass, potassium glass, borate glass, borosilicate glass, barium borosilicate glass, halite borate glass, barium borate glass, bismuth borosilicate glass, zinc bismuth borosilicate glass, bismuth silicate glass, phosphate glass, aluminophosphate glass, and halite phosphate glass. Furthermore, while not particularly limited, the ceramic material can be at least one selected from the group consisting of alumina (Al₂O₃), boron nitride (BN), silicon dioxide (SiO₂), silicon nitride (Si₃N₄), zirconium oxide (ZrO₂), aluminum nitride (AlN), silicon carbide (SiC), and barium titanate (BaTiO₃).

[0054] (terminal)

[0055] In the solid-state battery 200 of the present invention, terminals (external terminals) 40 (40A, 40B) are generally provided. In particular, positive and negative terminals 40A and 40B are provided in pairs on the side of the solid-state battery. More specifically, a positive terminal 40A connected to the positive electrode layer 10A and a negative terminal 40B connected to the negative electrode layer 10B are provided in pairs. The terminals 40A and 40B can be provided in such a way that they cover at least one side of the solid-state battery, and therefore can also be referred to as "end-face electrodes". Such terminals 40 (40A, 40B) can be made of materials with high conductivity. There are no particular limitations on the material of the terminals 40, and examples include at least one conductive material selected from the group consisting of silver, gold, platinum, aluminum, copper, tin, and nickel.

[0056] Terminals 40 (40A, 40B) may also contain sintering aids. Examples of sintering aids include materials similar to those found in the positive electrode layer 10A. In a preferred embodiment, terminals 40 (40A, 40B) are composed of a sintered body comprising at least a conductive material and a sintering aid.

[0057] (Outer layer material)

[0058] The solid-state battery 200 of the present invention typically also includes an outer layer material 60. The outer layer material 60 is generally formed on the outermost side of the solid-state battery for electrical, physical, and / or chemical protection. Preferably, the material constituting the outer layer material 60 has excellent insulation, durability, and / or moisture resistance, and is environmentally safe. For example, glass, ceramics, thermosetting resins, photocurable resins, and mixtures thereof can be used.

[0059] As the glass that can form the outer layer material, the same material as the glass material that can form the electrode separation section can be used. Furthermore, as the ceramic material that can form the outer layer material, the same material as the ceramic material that can form the electrode separation section can be used.

[0060] [Features of the solid-state battery of the present invention]

[0061] The inventors of this application have conducted in-depth research on solutions for reducing the interfacial resistance between the active material and the solid electrolyte in the negative electrode layer of a solid-state battery. As a result, the inventors of this application have proposed a new invention with technical features related to a specific combination of the negative electrode active material and the solid electrolyte in the negative electrode layer, as well as a specific range of the density of the negative electrode active material and the content of the solid electrolyte.

[0062] Specifically, the present invention has the following technical features: the negative electrode layer comprises a negative electrode active material containing a Li composite oxide and an oxide glass-based solid electrolyte, wherein, relative to the total amount of the negative electrode active material and the solid electrolyte in the negative electrode layer, the content of the solid electrolyte is 20% by mass or more and 60% by mass or less, and the ratio of the actual density B of the negative electrode active material to the true density A of the negative electrode active material, B / A, is 0.3 or more and 0.6 or less.

[0063] In addition, in this specification, "negative electrode active material and solid electrolyte in negative electrode layer" refers to the negative electrode active material and solid electrolyte located outside the voids of the negative electrode layer that can be formed in the final solid battery (equivalent to the finished product).

[0064] Based on the aforementioned technical characteristics, when the content of the solid electrolyte in the negative electrode layer is 20% by mass or more and 60% by mass or less, the actual density B of the negative electrode active material in the manufactured battery can be ensured to be a predetermined ratio (0.3 or more and 0.6 or less) relative to the true density A of the negative electrode active material. For example, the true density A of the aforementioned negative electrode active material is 3.0 g / cm³. 3 Above and 4.0 g / cm 3 The following is an example of a concentration of 3.5 g / cm³. 3 Furthermore, when the content of solid electrolyte in the negative electrode layer is 20% by mass or more, a predetermined amount of solid electrolyte is ensured compared to cases where it is less than 20% by mass.

[0065] Based on the above, the interface between the negative electrode active material and the solid electrolyte in the negative electrode layer can be made dense, thus appropriately forming a lithium-ion conduction pathway. That is, the interfacial resistance between the negative electrode active material and the solid electrolyte in the negative electrode layer can be reduced, allowing lithium ions to easily cross this interface. As a result, the internal resistance of the battery can be reduced, and the volumetric energy density can be increased.

[0066] Furthermore, if the content of the solid electrolyte in the negative electrode layer is 60% by mass or less, then compared to the case where it exceeds 60% by mass, the ratio of the actual density B of the negative electrode active material to the true density A of the negative electrode active material, B / A, can be ensured to be 0.3 or more. Therefore, in the manufactured battery, since the negative electrode active material occupies a predetermined amount in the negative electrode layer, the interparticle distance of the negative electrode active material in the negative electrode layer can be suppressed to a distance that allows for the formation of appropriate electron paths.

[0067] Based on the above, it is possible to ensure that the discharge capacity can achieve a charge-discharge efficiency of more than the predetermined benchmark value (above 85%), and to appropriately improve the battery characteristics of the solid-state battery.

[0068] The "true density of the negative electrode active material" mentioned in this specification refers to the inherent density of the predetermined type of negative electrode active material, and the "true density of the solid electrolyte" refers to the inherent density of the predetermined type of solid electrolyte. The true densities of the negative electrode active material and the solid electrolyte can be calculated using a helium gas phase displacement method, by determining the volume of the sample through pressure and volume changes, and then measuring the weight to calculate the true density. Furthermore, the "actual density of the negative electrode active material" mentioned in this specification refers to the volumetric density of the negative electrode active material in the negative electrode layer of the manufactured solid-state battery.

[0069] Furthermore, the actual density B of the negative electrode active material after battery fabrication can be calculated using the true density A of the negative electrode active material, the true density C of the solid electrolyte, the porosity E within the negative electrode, the content F of the negative electrode active material in the negative electrode layer, and the content G of the solid electrolyte. The calculation formula is shown below.

[0070] The volumetric proportion of the negative electrode active material (V1) = (100-E)×F / A / (F / A+G / C)

[0071] The actual density (B) of the prepared negative electrode active material = (A×V1) / 100

[0072] Furthermore, the porosity within the electrodes can be calculated by ion milling the obtained solid-state battery to form a smooth cross-section, and then observing it at 5000x magnification using SEM software such as ImageJ. Additionally, the content of the negative electrode active material (F) and the content of the solid electrolyte (G) can also be calculated using the same method.

[0073] Furthermore, in this invention, the content of the solid electrolyte is preferably 30% by mass or more and 50% by mass or less, relative to the total amount of the negative electrode active material and the solid electrolyte. In this case, compared with the same content of 20% by mass, by increasing the content of the solid electrolyte in the negative electrode layer by 10% by mass, the contact interface between the negative electrode active material and the solid electrolyte in the negative electrode layer can be made denser, and a more suitable lithium ion conduction path can be formed.

[0074] If the solid electrolyte content in the negative electrode layer is less than 50% by mass, compared to the same content of 60% by mass, increasing the mass of the negative electrode active material by 10% by mass can more appropriately suppress the interparticle distance of the negative electrode active material in the negative electrode layer to a distance that can form an electron path. Based on the above, it is possible to ensure a discharge capacity with a charge-discharge efficiency of more than 95% (above the predetermined baseline value), and to more appropriately improve the battery characteristics of the solid-state battery.

[0075] Furthermore, when the content of the solid electrolyte is always a predetermined amount (e.g., 40% by mass) relative to the total amount of the negative electrode active material and the solid electrolyte in the negative electrode layer, the ratio of the true density C of the solid electrolyte to the true density A of the negative electrode active material, C / A, can be 0.55 or more and 0.9 or less. For example, the true density C of the solid electrolyte can be 2.0 g / cm³. 3 Above and 3.0 g / cm 3 The preferred value is 2.0 g / cm³. 3 Above and 2.5g / cm 3 the following.

[0076] If the ratio C / A is within this range, then the actual density B of the negative electrode active material in the manufactured battery can be ensured to be a predetermined ratio (0.3 or more and 0.6 or less) relative to the true density A of the negative electrode active material. On the other hand, if the ratio C / A is outside this range (specifically 0.51), then the actual density B of the negative electrode active material in the manufactured battery cannot be ensured to be a predetermined ratio (0.3 or more and 0.6 or less) relative to the true density A of the negative electrode active material.

[0077] Based on the above, in the manufactured battery, ensuring a predetermined amount of negative electrode active material (and solid electrolyte) in the negative electrode layer can make the contact interface between the negative electrode active material and the solid electrolyte in the negative electrode layer dense, and can properly form a lithium ion conduction path.

[0078] Furthermore, when the aforementioned ratio C / A is 0.6 or higher and 0.75 or lower, the aforementioned ratio B / A can be 0.35 or higher and 0.5 or lower. In this case, compared to the case where the ratio C / A is less than 0.6, the aforementioned ratio B / A can be increased. As a result, in the manufactured battery, by more appropriately ensuring a predetermined amount of negative electrode active material (and solid electrolyte) in the negative electrode layer, the contact interface between the negative electrode active material and the solid electrolyte in the negative electrode layer can be made denser, and a more appropriate lithium-ion conduction path can be formed.

[0079] The Li composite oxide included in the aforementioned negative electrode active material can be an oxide containing Li and a transition metal element. For example, it can be an oxide containing at least one metal element selected from the group consisting of Li, titanium (Ti), silicon (Si), tin (Sn), chromium (Cr), iron (Fe), niobium (Nb), and molybdenum (Mo). For instance, the Li composite oxide included in the aforementioned negative electrode active material can be an oxide containing both Li and Ti. When using an oxide containing both Li and Ti, high energy density can be obtained while suppressing the expansion and contraction of the negative electrode layer during charging and discharging.

[0080] The aforementioned oxide glass-based solid electrolyte for the negative electrode layer has the advantage of contributing to a reduction in porosity within the negative electrode; for example, it can be lithium borosilicate glass. Lithium borosilicate glass is an oxide-based glass material containing at least lithium (Li), silicon (Si), and boron (B) as constituent elements; for example, it can be 50Li4SiO4·50Li3BO3. The low glass transition temperature of lithium borosilicate glass is advantageous in that it enables the formation of a dense negative electrode layer.

[0081] In addition to lithium borosilicate glass, which is a glass-based solid electrolyte, the aforementioned solid electrolyte may also include other known solid electrolytes used in solid-state batteries. Such solid electrolytes may be, for example, any one or more of crystalline solid electrolytes, glass-based solid electrolytes different from lithium borosilicate glass, and glass-ceramic solid electrolytes. Crystalline solid electrolytes are, for example, oxide-based crystalline materials. Examples of oxide-based crystalline materials include lithium phosphate compounds with a NASICON structure, oxides with a perovskite structure, oxides with a garnet-type or garnet-like structure, and oxide glass-ceramic lithium-ion conductors.

[0082] Examples of lithium phosphate compounds with a NASICON structure include Li x M y (PO4)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). As an example of a lithium phosphate compound having a NASICON structure, Li can be cited as an example. 1.2 Al 0.2 Ti 1.8 (PO4)3, etc. As an example of an oxide with a perovskite structure, La can be cited. 0.55 Li 0.35 TiO3, etc. As an example of oxides with garnet-type or garnet-like structures, Li7La3Zr2O can be cited. 12 Crystalline solid electrolytes can also contain polymeric materials (such as polyethylene oxide (PEO)).

[0083] As glass-based solid electrolytes that can be used besides lithium borosilicate glass, they include 30Li2S·26B2S3·44LiI, 63Li2S·36SiS2·1Li3PO4, 57Li2S·38SiS2·5Li4SiO4, 70Li2S·30P2S5, and 50Li2S·50GeS2, etc.

[0084] Glass-ceramic solid electrolytes include, for example, oxide-based glass-ceramic materials. As oxide-based glass-ceramic materials, examples include lithium-aluminum-titanium phosphate compounds (LATP) and lithium-aluminum-germanium phosphate compounds (LAGP). For example, Li... 1.07 Al 0.69 Ti 1.46 (PO4)3, etc. Furthermore, LAGP is, for example, Li. 1.5 Al 0.5 Ge 1.5 (PO4), etc.

[0085] For example, in addition to lithium borosilicate glass, solid electrolytes can also contain oxides with garnet-type or garnet-like structures from the perspective of improving ionic conductivity.

[0086] [Solid-state battery manufacturing method]

[0087] The solid-state battery of the present invention can be manufactured by printing methods such as screen printing, green sheet methods using green sheets, or a combination thereof. Hereinafter, for the purpose of understanding the present invention, the use of printing methods and green sheet methods will be described in detail, but the present invention is not limited to these methods. That is, the solid-state battery can be manufactured according to conventional solid-state battery manufacturing methods. Furthermore, the following order of description and other temporal details are merely for ease of explanation and are not necessarily limiting.

[0088] (Formation process of solid-state battery stacked precursor)

[0089] In this process, various pastes are used as inks, such as pastes for the positive electrode layer, pastes for the negative electrode layer, pastes for the solid electrolyte layer, pastes for the positive current collector layer, pastes for the negative current collector layer, pastes for the electrode separation section, and pastes for the outer layer material. That is, by applying and drying the pastes using a printing method, a solid battery laminate precursor with a predetermined structure is formed on a support substrate.

[0090] During printing, by sequentially stacking printing layers with predetermined thickness and pattern shape, a solid-state battery stacking precursor corresponding to the predetermined solid-state battery structure can be formed on a substrate. The type of pattern forming method is not particularly limited as long as it is capable of forming the predetermined pattern; for example, it can be any one or more of screen printing and gravure printing.

[0091] The paste can be prepared by wet mixing a predetermined constituent material selected appropriately from the group consisting of positive electrode active material particles, negative electrode active material particles, conductive material, solid electrolyte material, current collector layer material, insulating material and sintering aid, and other materials mentioned above, with an organic carrier in which the organic material is dissolved in a solvent.

[0092] The paste for the positive electrode layer may contain, for example, positive electrode active material particles, solid electrolyte material, organic material and solvent, and sintering aids as needed.

[0093] The paste used for the negative electrode layer may contain, for example, negative electrode active material particles, solid electrolyte material, organic material and solvent, and sintering aids as needed.

[0094] The paste for the solid electrolyte layer may contain, for example, solid electrolyte materials, organic materials and solvents, and sintering aids as needed.

[0095] The paste for the positive electrode current collector layer contains conductive materials, organic materials and solvents, as well as sintering aids as needed.

[0096] The paste for the negative electrode current collector layer contains conductive materials, organic materials and solvents, as well as sintering aids as needed.

[0097] The paste used for the electrode separation section may contain, for example, solid electrolyte materials, insulating materials, organic materials and solvents, as well as sintering aids as needed.

[0098] The outer layer material uses a paste that includes, for example, insulating materials, organic materials and solvents, as well as sintering aids as needed.

[0099] There are no particular limitations on the organic materials contained in the paste, and at least one polymeric material from the group consisting of polyvinyl acetal resin, cellulose resin, polyacrylic acid resin, polyurethane resin, polyvinyl acetate resin, and polyvinyl alcohol resin may be used.

[0100] There are no particular restrictions on the type of solvent, such as any one or more organic solvents including butyl acetate, N-methylpyrrolidone, toluene, terpineol, and N-methylpyrrolidone.

[0101] In wet mixing, a medium can be used; specifically, ball milling or high-viscosity bead milling can be used. On the other hand, wet mixing methods without a medium can be used, such as sand milling, high-pressure homogenization, or kneading dispersion.

[0102] The supporting substrate is not particularly limited as long as it can support the various paste layers; for example, it can be a release film that has undergone a release treatment on one side. Specifically, a substrate made of polymer materials such as polyethylene terephthalate can be used. When the paste layers are supplied to the firing process while held on the substrate, a substrate that is heat-resistant to the firing temperature can be used.

[0103] As another method, each paste can be used to form a green sheet, and the resulting green sheet can be used to make a solid-state battery stack precursor.

[0104] In detail, by drying the support substrate coated with various pastes on a hot plate heated to above 30°C and below 90°C, green sheets of positive electrode layer, green sheets of negative electrode layer, green sheets of solid electrolyte layer, green sheets of positive electrode current collector layer, green sheets of negative electrode current collector layer, green sheets of electrode separation part, and / or green sheets of outer layer material with predetermined shapes and thicknesses are formed on each support substrate (e.g., PET film).

[0105] Next, each green sheet is peeled off from the substrate. After peeling, the green sheets of each constituent element are sequentially stacked along the stacking direction, thereby forming a solid-state battery laminate precursor. After stacking, a solid electrolyte layer, an insulating layer, and / or a protective layer can also be provided to the side regions of the electrode green sheets by screen printing.

[0106] (Firing process)

[0107] In the sintering process, the solid-state battery stack precursor is sintered. Although this is merely an example, sintering is carried out in a nitrogen atmosphere containing oxygen or in the atmosphere, for example, after removing organic materials by heating at above 200°C, by heating in a nitrogen atmosphere or in the atmosphere at, for example, above 300°C and below 500°C. Firing can be performed simultaneously with pressurizing the solid-state battery stack precursor at 20–100 MPa in the stacking direction (depending on the case, the stacking direction and the direction perpendicular to that stacking direction).

[0108] Through this firing process, a solid-state battery stack is formed, ultimately yielding the desired solid-state battery.

[0109] (The formation process of positive and negative extrema)

[0110] For example, a conductive adhesive is used to bond the positive terminal to the solid-state battery stack, and a conductive adhesive is used to bond the negative terminal to the solid-state battery stack. Thus, the positive and negative terminals are respectively mounted on the solid-state battery stack. As a result, the desired solid-state battery can be obtained.

[0111] The embodiments of the present invention have been described above, but these are merely typical examples. Therefore, the present invention is not limited thereto, and those skilled in the art will readily understand that various methods can be considered without changing the spirit of the present invention.

[0112] Example

[0113] The following describes the embodiments.

[0114] <Example 1>

[0115] (The manufacturing process of raw sheets for solid electrolyte layers)

[0116] First, halogenated lithium borosilicate glass (a lithium borosilicate glass in 60Li₂O-10SiO₂-30B₂O₃ in which 10% of the O is replaced with Cl) and an acrylic binder, used as the solid electrolyte, were mixed at a mass ratio of lithium borosilicate glass:acrylic binder = 70:30. The true density of the solid electrolyte used in Example 1 was 2.5 g / cm³. 3 .

[0117] Next, the resulting mixture was added to butyl acetate as a solvent at a solid content of 30% by mass, and then stirred with zirconia balls with a diameter of 5 mm for 4 hours to obtain a paste for a solid electrolyte layer. This paste was then coated onto a release film and dried at 80°C for 20 minutes to produce a green sheet for a solid electrolyte layer as a precursor.

[0118] (The manufacturing process of the green sheet for the positive electrode material layer)

[0119] First, lithium cobalt oxide (LiCoO2) is prepared. Next, LiCoO2 (as the positive electrode active material), solid electrolyte (for the green sheet used in the solid electrolyte layer), and acrylic binder are mixed at a mass ratio of LiCoO2:solid electrolyte:binder = 70:20:10. Then, the resulting mixture is added to terpineol with a solid content of 60% by mass. The resulting mixture is then stirred with zirconia balls with a diameter of 5 mm for 1 hour to obtain a paste for the positive electrode material layer. Next, this paste is coated onto a release film and dried at 80°C for 20 minutes to produce a green sheet for the positive electrode material layer as a precursor.

[0120] (The manufacturing process of the green sheet for the negative electrode material layer)

[0121] First, Li4Ti5O is used as the negative electrode active material. 12 (Merck, Product No. 915939), solid electrolyte and acrylic binder used as solid electrolyte in the above-mentioned solid electrolyte layer green sheet, with Li4Ti5O 12 Solid electrolyte: binder = 72:18:10 by mass ratio.

[0122] The true density of the negative electrode active material used is 3.5 g / cm³. 3 .

[0123] Next, the resulting mixture was added to terpineol with a solid content of 60% by mass. Then, the resulting mixture was stirred with zirconia balls with a diameter of 5 mm for 1 hour to obtain a paste for the negative electrode material layer. The paste was then coated onto a release film and dried at 80°C for 20 minutes to produce a green sheet for the negative electrode material layer as a precursor.

[0124] (The manufacturing process of the green sheet for the positive current collector layer)

[0125] First, carbon powder (manufactured by Resonac, product number VGCF (registered trademark)-F), a solid electrolyte used as a solid electrolyte for the green sheet of the aforementioned solid electrolyte layer, and an acrylic binder are mixed at a mass ratio of carbon powder: solid electrolyte: binder = 70:20:10. Next, the resulting mixture is added to terpineol with a solid content of 60% by mass. Then, the resulting mixture is stirred with zirconia balls with a diameter of 5 mm for 1 hour to obtain a paste for the positive current collector layer. Next, this paste is coated onto a release film and dried at 80°C for 20 minutes, thereby producing a green sheet for the positive current collector layer as a precursor.

[0126] (The manufacturing process of the green sheet for the negative electrode current collector layer)

[0127] The negative electrode current collector layer green sheet is manufactured in the same manner as the above-mentioned positive electrode current collector layer green sheet manufacturing process.

[0128] (The process of making the outer layer material from raw sheets)

[0129] First, alumina powder (manufactured by High Purity Chemical Research Co., Ltd., product number γ-Al2O3 alumina), solid electrolyte for the aforementioned solid electrolyte layer green sheet, and acrylic binder are mixed at a mass ratio of carbon powder:solid electrolyte:binder = 70:20:10. Next, the resulting mixture is added to terpineol with a solid content of 60% by mass. Then, the resulting mixture is stirred with zirconia balls with a diameter of 5 mm for 1 hour to obtain a paste for the main surface coating material. This paste is then applied to a release film and dried to produce a green sheet for the outer layer material as a precursor.

[0130] (The manufacturing process of the green sheet for the electrode separation section)

[0131] The same process as that used for manufacturing the outer layer material green sheet is used to manufacture the electrode separation section green sheet as the electrode separation section precursor.

[0132] (The manufacturing process of laminated bodies)

[0133] Using the raw films obtained in the above manner, prepare films with the following characteristics: Figure 1 as well as Figure 2 The structure shown is a laminated body. Specifically, firstly, the raw sheets are processed into... Figure 1 as well as Figure 2 After shaping as shown, demold from the release film. Next, place each green sheet with... Figure 1 as well as Figure 2 After the battery elements shown are stacked sequentially in the manner corresponding to their configuration, they are thermally bonded by applying pressure in the thickness direction while heating to 100°C. This yields a laminated body that serves as a precursor for the battery elements.

[0134] (Degreasing and sintering processes of laminated bodies)

[0135] The acrylic binder contained in each green sheet was removed by heating the obtained laminate at 300°C for 10 hours. Then, the laminate with the acrylic binder removed was heated at 350°C for 10 minutes while applying pressure in the thickness direction at 20-100 MPa. After that, it was cooled in the atmosphere for 1 hour to obtain the sintered laminate.

[0136] (Terminal manufacturing process)

[0137] Next, a conductive adhesive (thermosetting silver paste) is used to bond the silver plate to the first and second end faces (or sides) of the stack exposed on the positive and negative current collector layers, thereby forming the positive and negative terminals and fabricating a solid battery.

[0138] In addition to, or alternatively to, the fabrication, degreasing, and sintering processes of the aforementioned laminate, multiple green sheets of the aforementioned solid electrolyte layer, punched with a diameter of φ16 mm, and green sheets of the aforementioned negative electrode material layer, punched with a diameter of φ8 mm, are sequentially laminated onto SUS304 (φ16 mm, thickness 0.3 mm). Subsequently, the binder contained in the green sheets is degreased at 300°C using a muffle furnace KDF P-90 (manufactured by Dengen). The sample, after degreasing, is heated at 350°C for 10 minutes under pressure in the thickness direction at 20–100 MPa in a pressure sintering machine P-5058-00 (manufactured by NPa System), and then sintered to obtain a battery element. Subsequently, a 100 μm thick Li foil, punched with a diameter of φ10 mm, is bonded to the battery element, thereby fabricating the half-cell used in this evaluation. In addition, in the manufactured battery, with the removal of acrylic binder, the mass ratio of negative electrode active material to solid electrolyte is 80:20.

[0139] <Example 2>

[0140] In Example 2, in the fabrication process of the green sheet for the negative electrode material layer in Example 1, Li4Ti5O was used. 12The solid electrolyte and binder were mixed at a mass ratio of 63:27:10. Except for this, the solid battery was manufactured using the same method as in Example 1. Furthermore, in the manufactured battery, with the removal of the acrylic binder, the mass ratio of the negative electrode active material to the solid electrolyte was 70:30 (based on mass).

[0141] <Example 3>

[0142] In Example 3, during the fabrication process of the negative electrode material layer green sheet in Example 1, Li4Ti5O was used. 12 The solid electrolyte and binder were mixed in a mass ratio of 54:36:10. Except for this, the solid battery was manufactured using the same method as in Example 1. Furthermore, in the manufactured battery, with the removal of the acrylic binder, the mass ratio of the negative electrode active material to the solid electrolyte was 60:40.

[0143] <Example 4>

[0144] In Example 4, during the fabrication process of the negative electrode material layer green sheet in Example 1, Li4Ti5O was used. 12 The solid electrolyte and binder were mixed in a mass ratio of 45:45:10. Except for this, the solid battery was manufactured using the same method as in Example 1. Furthermore, in the manufactured battery, with the removal of the acrylic binder, the mass ratio of the negative electrode active material to the solid electrolyte was 50:50.

[0145] <Example 5>

[0146] In Example 5, in the fabrication process of the green sheet for the negative electrode material layer in Example 1, Li4Ti5O was used. 12 The solid electrolyte and binder were mixed in a mass ratio of 36:54:10. Except for this, the solid battery was manufactured using the same method as in Example 1. Furthermore, in the manufactured battery, with the removal of the acrylic binder, the mass ratio of the negative electrode active material to the solid electrolyte was 40:60.

[0147] <Example 6>

[0148] In Example 6, similar to Example 3, in the fabrication process of the green sheet for the negative electrode material layer, Li4Ti5O was used. 12The solid electrolyte and binder were mixed in a mass ratio of 54:36:10. That is, in the manufactured battery, with the removal of the acrylic binder, the mass ratio of the negative electrode active material to the solid electrolyte was 60:40. On the other hand, in Example 6, unlike Example 3, the composition ratios of Li, B, and Si, the main components of the solid electrolyte, were adjusted. For example, by reducing the Si content ratio, a true density of 2.2 g / cm³ was achieved when using the solid electrolyte. 3 Solid electrolytes.

[0149] <Example 7>

[0150] In Example 7, similar to Example 3, in the fabrication process of the green sheet for the negative electrode material layer, Li4Ti5O was used. 12 The solid electrolyte and binder were mixed at a mass ratio of 54:36:10. That is, in the manufactured battery, with the removal of the acrylic binder, the mass ratio of the negative electrode active material to the solid electrolyte was 60:40. On the other hand, in Example 7, unlike Example 3, by adjusting the composition ratio of Li, B, and Si components, which are the main components of the solid electrolyte, for example by further reducing the Si content ratio, a true density of 2.0 g / cm³ was achieved when using it as a solid electrolyte. 3 Solid electrolytes.

[0151] <Comparative Example 1>

[0152] In Comparative Example 1, during the fabrication process of the green sheet for the negative electrode material layer in Example 1, Li4Ti5O was used. 12 The solid electrolyte and binder were mixed in a mass ratio of 81:9:10. Except for this, the solid battery was manufactured using the same method as in Example 1. Furthermore, in the manufactured battery, with the removal of the acrylic binder, the mass ratio of the negative electrode active material to the solid electrolyte was 90:10.

[0153] <Comparative Example 2>

[0154] In Comparative Example 2, during the fabrication process of the green sheet for the negative electrode material layer in Example 1, Li4Ti5O was used. 12 The solid electrolyte and binder were mixed in a mass ratio of 27:63:10. Except for this, the solid battery was manufactured using the same method as in Example 1. Furthermore, in the manufactured battery, with the removal of the acrylic binder, the mass ratio of the negative electrode active material to the solid electrolyte was 30:70.

[0155] <Comparative Example 3>

[0156] In Comparative Example 3, similar to Example 3, in the fabrication process of the green sheet for the negative electrode material layer, Li4Ti5O was used.12 The solid electrolyte and binder were mixed in a mass ratio of 54:36:10. That is, in the manufactured battery, with the removal of the acrylic binder, the mass ratio of the negative electrode active material to the solid electrolyte was 60:40. On the other hand, in Comparative Example 3, unlike Example 3, by adjusting the composition ratio of Li, B, and Si components, which are the main components of the solid electrolyte, for example by further reducing the Si content ratio, a true density of 1.8 g / cm³ was achieved when using it as a solid electrolyte. 3 Solid electrolytes.

[0157] [Measurement Content]

[0158] (Determination of battery characteristics)

[0159] The aforementioned half-cell was placed in a cryostat (Yamato Scientific, model IQ822), and then charge-discharge tests were conducted using a charge-discharge evaluation device (Toyo Systems, model TOSCAT-3100). The charge-discharge conditions are as follows: The battery's rated capacity was set to 1C, and it was charged to a predetermined potential (cutoff voltage 4V) at a constant current of 0.05C. Then, it was discharged to the predetermined potential at a constant current of 0.05C, and after reaching the predetermined potential, it was discharged in a constant voltage mode until the current decreased to 0.005C (cutoff voltage 1.0V). Through these charge-discharge tests, the charge-discharge capacity of the half-cell was confirmed.

[0160] [Measurement Result 1]

[0161] Table 1 shows the measurement results related to Examples 1 to 5 and Comparative Examples 1 to 2. In these examples and comparative examples, the charging capacity was approximately 170 mAh / g. Based on this value, the charge-discharge efficiency was calculated according to the ratio of discharge capacity to charging capacity. A charge-discharge efficiency of 85% or higher was defined as 0, a charge-discharge efficiency of 95% or higher was defined as ◎, and a charge-discharge efficiency of less than 85% or a case where the discharge capacity could not be measured was defined as ×.

[0162] Table 1

[0163]

[0164] As shown in Examples 1 to 5 of Table 1, it can be seen that in the obtained battery, the content ratio (mass basis) of negative electrode active material to solid electrolyte is 80:20 to 40:60. That is, when the content of solid electrolyte is 20% or more and 60% or less relative to the total amount of negative electrode active material and solid electrolyte, and the ratio of the actual density B of negative electrode active material to the true density A of negative electrode active material B / A is 0.3 or more and 0.6 or less, the charge-discharge efficiency is 85% or more.

[0165] It is evident that, especially when the ratio of negative electrode active material to solid electrolyte is 70:30 to 50:50, that is, when the content of solid electrolyte is 30% to 50% by mass relative to the total amount of negative electrode active material and solid electrolyte, the charge-discharge efficiency is above 95%. At this point, the density of the prepared negative electrode active material B is 0.3 g / cm³. 3 Above and 0.5g / cm 3 the following.

[0166] On the other hand, as shown in Comparative Example 1, when the mass ratio of negative electrode active material to solid electrolyte is 90:10, that is, when the content of solid electrolyte is 10% by mass relative to the total amount of negative electrode active material and solid electrolyte, and the porosity in the negative electrode layer is less than 20.0% by volume, although a battery can be manufactured, the discharge capacity cannot be measured. From the above, it can be seen that because the content of negative electrode active material is high and the content of solid electrolyte is low, the contact interface between the negative electrode active material and the solid electrolyte cannot be made dense, and a lithium-ion conduction pathway cannot be formed.

[0167] Furthermore, as shown in Comparative Example 2, it can be seen that the mass ratio of the negative electrode active material to the solid electrolyte is 30:70. That is, when the content of the solid electrolyte is 70% by mass relative to the total mass of the negative electrode active material and the solid electrolyte, and the ratio of the actual density B of the negative electrode active material to the true density A of the negative electrode active material (B / A) is less than 0.3, the charge-discharge efficiency is less than 85%. From the above, it can be seen that if the content of the solid electrolyte in the negative electrode layer exceeds 60% by mass and the ratio B / A is less than 0.3, the interparticle distance of the negative electrode active material cannot be made to a distance that can form an electron path.

[0168] As can be seen from the above, within the scope of Examples 1 to 5, the contact interface between the negative electrode active material and the solid electrolyte can be made dense, a lithium ion conduction path can be appropriately formed, and the interparticle distance of the negative electrode active material in the negative electrode layer can be a distance that can form an appropriate electronic path.

[0169] [Measurement Result 2]

[0170] Table 2 shows the measurement results related to Examples 3, 6, 7, and Comparative Example 3. In these examples and comparative examples, as in Example 1, the charging capacity was approximately 170 mAh / g. Based on this value, the charge / discharge efficiency was calculated according to the ratio of discharge capacity to charging capacity. A charge / discharge efficiency of 85% or higher was defined as '0', a charge / discharge efficiency of 95% or higher was defined as '◎', and a charge / discharge efficiency less than 85% or where the discharge capacity could not be measured was defined as '×'.

[0171] Table 2

[0172]

[0173] As shown in Examples 3, 6, and 7 of Table 2, it can be seen that in the obtained batteries, the content ratio of negative electrode active material to solid electrolyte is consistently 60:40. That is, when the content of solid electrolyte is consistently 40% by mass relative to the total amount of negative electrode active material and solid electrolyte, if the ratio C / A of the true density C of the solid electrolyte to the true density A of the negative electrode active material is 0.55 or more and 0.9 or less, then the ratio B / A is 0.3 or more and 0.5 or less, ensuring a charge-discharge efficiency of 85% or more. In particular, as shown in Examples 3 and 6, it can be seen that when the ratio C / A is 0.6 or more and 0.75 or less, the ratio B / A is 0.35 or more and 0.5 or less, ensuring a charge-discharge efficiency of 95% or more. On the other hand, it can be seen that if the ratio C / A is less than 0.55, then the ratio B / A is less than 0.3, and the charge-discharge efficiency is less than 85%.

[0174] As can be seen from the above, in the negative electrode layer, when a predetermined amount of solid electrolyte is included relative to the total amount of negative electrode active material and solid electrolyte, the ratio C / A of the true density C of the solid electrolyte to the true density A of the negative electrode active material is also related to the charge and discharge efficiency, i.e., battery characteristics.

[0175] Alternatively, the present invention can be implemented in the following manner.

[0176] <1> A solid-state battery,

[0177] The solid-state battery has a negative electrode layer, which comprises a negative electrode active material containing a Li composite oxide and an oxide glass-based solid electrolyte.

[0178] In the negative electrode layer, the content of the solid electrolyte is 20% by mass or more and 60% by mass or less, relative to the total amount of the negative electrode active material and the solid electrolyte.

[0179] The ratio of the actual density B of the negative electrode active material to the true density A of the negative electrode active material, B / A, is greater than 0.3 and less than 0.6.

[0180] <2> According to the solid-state battery described in <1>, wherein,

[0181] The content of the solid electrolyte is 30% by mass or more and 50% by mass or less relative to the total amount of the negative electrode active material and the solid electrolyte.

[0182] <3> According to <1> or <2>, in the solid-state battery,

[0183] The ratio of the true density C of the solid electrolyte to the true density A of the negative electrode active material, C / A, is 0.55 or higher and 0.9 or lower.

[0184] <4> According to the solid-state battery described in <3>, wherein,

[0185] When the C / A ratio is 0.6 or higher and 0.75 or lower, the B / A ratio is 0.35 or higher and 0.5 or lower.

[0186] <5> A solid-state battery according to any one of <1> to <4>, wherein,

[0187] The true density A of the negative electrode active material is 3.0 g / cm³. 3 Above and 4.0 g / cm 3 the following.

[0188] <6> According to <3> or <4>, in the solid-state battery,

[0189] The true density C of the solid electrolyte is 2.0 g / cm³. 3 Above and 3.0 g / cm 3 the following.

[0190] <7> A solid-state battery according to any one of <1> to <6>, wherein,

[0191] The Li composite oxide is an oxide containing Li and transition metal elements.

[0192] <8> According to the solid-state battery described in <7>, wherein,

[0193] The Li composite oxide is an oxide containing both Li and Ti.

[0194] <9> A solid-state battery according to any one of <1> to <8>, wherein,

[0195] The solid electrolyte is lithium borosilicate glass.

[0196] <10> A solid-state battery according to any one of <1> to <9>, wherein,

[0197] The solid-state battery also includes a positive electrode layer, which comprises a positive electrode active material containing a Li composite oxide and a solid electrolyte based on the oxide glass system.

[0198] <11> According to the solid-state battery described in <10>, wherein,

[0199] The Li composite oxide of the positive electrode active material is an oxide containing Li and Co.

[0200] Industrial applicability

[0201] The solid-state battery of the present invention can be used in various fields of envisioned energy storage. Although only illustrative, the solid-state battery of the present invention can be used in electrical / information / communication fields using mobile devices, etc. (e.g., electrical / electronic equipment fields or mobile device fields including mobile phones, smartphones, laptops and small electronic devices such as digital cameras, activity meters, wrist computers, electronic paper, RFID tags, card electronic money, smartwatches, etc.), home / small industrial applications (e.g., power tools, golf carts, home / care / industrial robots), large industrial applications (e.g., forklifts, elevators, port cranes), transportation systems (e.g., hybrid vehicles, electric vehicles, buses, trams, electric-assisted bicycles, electric motorcycles, etc.), power system applications (e.g., various power generation, load regulators, smart grids, general household energy storage systems, etc.), medical applications (medical devices such as headphones and hearing aids), pharmaceutical applications (medical management systems, etc.), IoT fields, space / deep-sea applications (e.g., space probes, underwater research vessels, etc.), etc.

[0202] Explanation of reference numerals in the attached figures

[0203] 10: Electrode layer; 10A: Positive electrode layer; 10B: Negative electrode layer; 11: Electrode current collector layer; 11A: Positive current collector layer; 11B: Negative current collector layer; 20: Solid electrolyte layer; 30: Electrode separation section; 30A: Positive electrode separation section; 30B: Negative electrode separation section; 40: Terminal; 40A: Positive terminal; 40B: Negative terminal; 60: Outer layer material; 100: Solid battery stack; 200: Solid battery.

Claims

1. A solid-state battery, The solid-state battery has a negative electrode layer, which comprises a negative electrode active material containing a Li composite oxide and an oxide glass-based solid electrolyte. In the negative electrode layer, the content of the solid electrolyte is 20% by mass or more and 60% by mass or less, relative to the total amount of the negative electrode active material and the solid electrolyte. The ratio of the actual density B of the negative electrode active material to the true density A of the negative electrode active material, B / A, is greater than 0.3 and less than 0.

6.

2. The solid-state battery according to claim 1, wherein, The content of the solid electrolyte is 30% by mass or more and 50% by mass or less relative to the total amount of the negative electrode active material and the solid electrolyte.

3. The solid-state battery according to claim 1 or 2, wherein, The ratio of the true density C of the solid electrolyte to the true density A of the negative electrode active material, C / A, is 0.55 or higher and 0.9 or lower.

4. The solid-state battery according to claim 3, wherein, When the C / A ratio is 0.6 or higher and 0.75 or lower, the B / A ratio is 0.35 or higher and 0.5 or lower.

5. The solid-state battery according to any one of claims 1 to 4, wherein, The true density A of the negative electrode active material is 3.0 g / cm³. 3 Above and 4.0 g / cm 3 the following.

6. The solid-state battery according to claim 3 or 4, wherein, The true density C of the solid electrolyte is 2.0 g / cm³. 3 Above and 3.0 g / cm 3 the following.

7. The solid-state battery according to any one of claims 1 to 6, wherein, The Li composite oxide is an oxide containing Li and transition metal elements.

8. The solid-state battery according to claim 7, wherein, The Li composite oxide is an oxide containing both Li and Ti.

9. The solid-state battery according to any one of claims 1 to 8, wherein, The solid electrolyte is lithium borosilicate glass.

10. The solid-state battery according to any one of claims 1 to 9, wherein, The solid-state battery also includes a positive electrode layer, which comprises a positive electrode active material containing a Li composite oxide and a solid electrolyte based on the oxide glass system.

11. The solid-state battery according to claim 10, wherein, The Li composite oxide of the positive electrode active material is an oxide containing Li and Co.

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