Solid-state battery and method for manufacturing solid-state battery

Abstract

A solid-state battery is provided in an embodiment of the present invention. The solid-state battery is characterized by including: a battery element having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer interposed between the positive electrode layer and the negative electrode layer; an end surface electrode provided to oppose an end surface of the battery element; a cover layer provided to cover the battery element with the end surface electrode; and an insulating buffer layer provided between the cover layer and the battery element so as to surround the battery element, the insulating buffer layer being interposed between the battery element and the end surface electrode on a side of an end surface electrode opposing region of the end surface of the battery element and being provided discontinuously.

Description

Technical Field

[0001] This invention relates to solid-state batteries and methods for manufacturing solid-state batteries. Background Technology

[0002] In the past, rechargeable batteries have been used for a wide variety of purposes. For example, they are used as power sources for electronic devices such as smartphones and laptops.

[0003] In conventional secondary batteries, liquid electrolytes such as organic solvents are used as the medium for ion movement. However, secondary batteries using liquid electrolytes suffer from problems such as electrolyte leakage. Therefore, the development of solid-state batteries, which use solid electrolytes instead of liquid electrolytes, is underway.

[0004] Prior art literature

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2018-49839 Summary of the Invention

[0007] The technical problem that the invention aims to solve

[0008] As a solid-state battery, there exists a solid-state battery comprising a battery element, an outer packaging surrounding the surface of the battery element, and a lubricant between the battery element and the outer packaging. The battery element has a positive electrode layer and a negative electrode layer facing each other, and a solid electrolyte layer between the positive and negative electrode layers (see Patent Document 1). Such a lubricant is sometimes disposed between the entire circumferential surface of the battery element and the inner surface of the outer packaging facing the entire circumferential surface.

[0009] Here, the inventors of this application note that there are aspects of the aforementioned solid-state battery that require further improvement. Specifically, when an end-face electrode is provided on the end face side of the battery element, if a lubricant is present on the entire circumference of the battery element, a lubricant will also be present between the battery element and the end-face electrode. As a result, due to the presence of the lubricant, the electrode layer of the battery element and the end-face electrode may become difficult to contact. In addition, the electrode layer (positive electrode layer / negative electrode layer) of the solid-state battery may expand and contract during charging and discharging, and thus, the outer packaging may peel off from the battery element with the end-face electrode due to such expansion and contraction, resulting in damage to the end face of the battery element.

[0010] The present invention was made in view of the following circumstances. That is, the main objective of the present invention is to provide a solid-state battery and a method thereof capable of simultaneously ensuring contact between the electrode layer and the end-face electrode and suppressing damage to the end face of the battery element.

[0011] Technical solutions for solving technical problems

[0012] To achieve the above objectives, in one embodiment of the present invention, a solid-state battery is provided, comprising: a battery element having a positive electrode layer, a negative electrode layer, and a solid electrolyte layer between the positive electrode layer and the negative electrode layer; an end electrode disposed opposite to an end face of the battery element; a cover layer disposed to cover the battery element having the end electrode; and an insulating buffer layer disposed between the cover layer and the battery element and surrounding the battery element, wherein the insulating buffer layer is sandwiched between the battery element and the end electrode on the side of the end face of the battery element and is disposed intermittently.

[0013] To achieve the above objectives, in one embodiment of the present invention, a method for manufacturing a solid-state battery is provided, comprising: step (i), stacking a positive electrode layer sheet, a solid electrolyte layer sheet, and a negative electrode layer sheet along a stacking direction to form an unburned laminate; step (ii), supplying an insulating material to the surface of the unburned laminate; step (iii), firing the unburned laminate with the insulating material to form a fired laminate; step (iv), providing an end-face electrode on the surface of the fired laminate; and step (v), forming a coating layer to cover the fired laminate with the end-face electrode, wherein in step (ii), the insulating material is intermittently supplied to the surface of the unburned laminate that will face the end-face electrode.

[0014] Invention Effects

[0015] According to one embodiment of the present invention, it is possible to simultaneously ensure contact between the electrode layer and the end face electrode and suppress damage to the end face of the battery element. Attached Figure Description

[0016] Figure 1 It is a schematic representation of from Figure 2 A cross-sectional view of a solid-state battery according to an embodiment of the present invention when viewed in the X-X' direction.

[0017] Figure 2 This is a schematic partial perspective view of a solid-state battery according to an embodiment of the present invention.

[0018] Figure 3 It is a schematic representation of from Figure 4 A cross-sectional view of a solid-state battery according to an embodiment of the present invention when viewed in the Y-Y' direction.

[0019] Figure 4 This is a schematic partial perspective view of a solid-state battery according to an embodiment of the present invention.

[0020] Figure 5This is a graph showing the voltage-capacity curve from Experiment Example 3. Detailed Implementation

[0021] Before describing a solid-state battery according to one embodiment of the present invention, the basic structure of a solid-state battery will be described first. In this specification, "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 (especially all constituent elements) are made of solids. In a suitable embodiment, the solid-state battery of the present invention is a stacked solid-state battery configured as layers forming battery constituent units stacked on top of each other; preferably, such layers are made of sintered bodies. The term "solid-state battery" in this specification can include not only rechargeable and dischargeable secondary batteries, but also primary batteries that can only be discharged. In a suitable embodiment of the present invention, the solid-state battery is a secondary battery. The term "secondary battery" is not overly limited in its name; for example, it may also include energy storage devices, etc.

[0022] The term "sectional view" as used in this specification refers to the state of a solid-state battery when viewed from a direction approximately perpendicular to the thickness direction, where the thickness direction is based on the stacking direction of the material layers constituting the solid-state battery. The terms "up / down" and "left / right" as used directly or indirectly in this specification correspond to the up / down and left / right directions in the figures, respectively. Unless otherwise specified, the same symbols or notations are considered to represent the same parts / areas or have the same meaning. In a suitable manner, it can be understood that the vertical direction downwards (i.e., the direction of gravity) corresponds to the "downward direction," and its opposite direction corresponds to the "upward direction."

[0023] Unless otherwise specified, the various numerical ranges mentioned in this specification are intended to include both the lower and upper limits of the value itself. That is, for example, a numerical range of 1 to 10 can be interpreted as including both the lower limit "1" and the upper limit "10" unless otherwise specified.

[0024] [The structure of a solid-state battery]

[0025] A solid-state battery is comprised of at least two electrode layers, a positive electrode and a negative electrode, and a solid electrolyte. Specifically, a solid-state battery comprises a battery element, end electrodes, and a capping layer. The battery element includes a battery unit consisting of a positive electrode layer, a negative electrode layer, and a solid electrolyte layer between them. The end electrodes are electrodes positioned facing the end faces of the battery element. The capping layer is configured to cover the battery element with the end electrodes.

[0026] In a solid-state battery, during the sintering process to form the various layers constituting the battery, the positive electrode layer, negative electrode layer, and solid electrolyte form sintered layers. Preferably, the positive electrode layer, negative electrode layer, and solid electrolyte are sintered integrally with each other, thus forming a single sintered body for the battery element.

[0027] The positive electrode layer is an electrode layer comprising at least a positive electrode active material. The positive electrode layer may also include a solid electrolyte. For example, the positive electrode layer is composed of a sintered body comprising at least positive electrode active material particles and solid electrolyte particles. In a preferred embodiment, the positive electrode layer is composed of a sintered body substantially comprising only positive electrode active material particles and solid electrolyte particles. On the other hand, the negative electrode layer is an electrode layer comprising at least a negative electrode active material. The negative electrode layer may also include a solid electrolyte. For example, the negative electrode layer is composed of a sintered body comprising at least negative electrode active material particles and solid electrolyte particles. In a preferred embodiment, the negative electrode layer is composed of a sintered body substantially comprising only negative electrode active material particles and solid electrolyte particles.

[0028] Positive and negative electrode active materials are substances that participate in electron transfer in a solid-state battery. Charge and discharge occur through the movement (conduction) of ions between the positive and negative electrode layers via the solid electrolyte. The positive and negative electrode layers are particularly preferably layers capable of intercalating and deintercalating lithium ions or sodium ions. In other words, a solid-state battery is preferably an all-solid-state secondary battery in which lithium ions move between the positive and negative electrode layers via the solid electrolyte for charging and discharging.

[0029] (Positive electrode active material)

[0030] Examples of positive electrode active materials included in the positive electrode layer include at least one selected from the group consisting of lithium phosphate compounds having a NASICON-type structure, lithium phosphate compounds having an olivine-type structure, lithium-containing layered oxides, and lithium-containing oxides having a spinel-type structure. Examples of lithium phosphate compounds having a NASICON-type structure include Li3V2(PO4)3. Examples of lithium phosphate compounds having an olivine-type structure include LiFePO4 and LiMnPO4. Examples of lithium-containing layered oxides include LiCoO2 and LiCo... 1 / 3 Ni 1 / 3 Mn 1 / 3O2, etc. Examples of lithium-containing oxides with a spinel-type structure include LiMn2O4 and LiNi. 0.5 Mn 1.5O4, etc. The types of lithium compounds are not particularly limited; for example, they can be lithium transition metal complex oxides and lithium transition metal phosphates. Lithium transition metal complex oxides are a general term for oxides containing lithium and one or more transition metal elements as constituent elements, and lithium transition metal phosphates are a general term for phosphate compounds containing lithium and one or more transition metal elements as constituent elements. The types of transition metal elements are not particularly limited; for example, they can be cobalt (Co), nickel (Ni), manganese (Mn), and iron (Fe).

[0031] Furthermore, as a positive electrode active material capable of intercalating and deintercalating sodium ions, examples include at least one selected from the group consisting of sodium phosphate compounds having a NASICON-type structure, sodium phosphate compounds having an olivine-type structure, sodium-containing layered oxides, and sodium-containing oxides having a spinel-type structure. For example, in the case of sodium phosphate compounds, examples include at least one selected from the group consisting of Na3V2(PO4)3, NaCoFe2(PO4)3, Na2Ni2Fe(PO4)3, Na3Fe2(PO4)3, Na2FeP2O7, Na4Fe3(PO4)2(P2O7), and NaFeO2 as a sodium-containing layered oxide.

[0032] In addition, the positive electrode active material can also be an oxide, disulfide, chalcogenide, or conductive polymer. Oxides can be, for example, titanium oxide, vanadium oxide, or manganese dioxide. Disulfides can be, for example, titanium disulfide or molybdenum sulfide. Chalcogenides can be, for example, niobium selenide. Conductive polymers can be, for example, disulfides, polypyrrole, polyaniline, polythiophene, poly(p-styrene), polyacetylene, or poly(phenylene oxide).

[0033] (Negative electrode active material)

[0034] Examples of negative electrode active materials included in the negative electrode layer include at least one selected from the group consisting of oxides, graphite-lithium compounds, lithium alloys, lithium phosphate compounds with a NASICON-type structure, lithium phosphate compounds with an olivine-type structure, and lithium oxides with a spinel-type structure, wherein the oxide includes at least one element selected from the group consisting of Ti, Si, Sn, Cr, Fe, Nb, and Mo. Examples of lithium alloys include Li-Al. Examples of lithium phosphate compounds with a NASICON-type structure include Li3V2(PO4)3 and LiTi2(PO4)3. Examples of lithium phosphate compounds with an olivine-type structure include LiCuPO4. Examples of lithium oxides with a spinel-type structure include Li4Ti5O. 12 wait.

[0035] In addition, as a negative electrode active material capable of intercalating and deintercalating sodium ions, at least one can be selected from the group consisting of sodium phosphate compounds having a NASICON-type structure, sodium phosphate compounds having an olivine-type structure, and sodium oxides having a spinel-type structure.

[0036] It should be noted that in a suitable embodiment of the solid-state battery of the present invention, the positive electrode layer and the negative electrode layer are made of the same material.

[0037] The positive and / or negative electrode layers may also include conductive additives. Examples of conductive additives included in the positive and negative electrode layers include at least one material composed of metals such as silver, palladium, gold, platinum, aluminum, copper, and nickel, as well as carbon. While not particularly limited, carbon is preferred because it does not readily react with the positive electrode active material, the negative electrode active material, and the solid electrolyte material, thus effectively reducing the internal resistance of the solid-state battery.

[0038] Furthermore, the positive electrode layer and / or negative electrode layer may also include sintering aids. Examples of sintering aids include at least one selected from the group consisting of lithium oxide, sodium oxide, potassium oxide, boron oxide, silicon oxide, bismuth oxide, and phosphorus oxide.

[0039] (Solid electrolyte)

[0040] Solid electrolytes are materials capable of conducting lithium ions. Specifically, in solid-state batteries, the solid electrolyte, forming a cell unit, creates a layer between the positive and negative electrode layers capable of conducting lithium or sodium ions. It should be noted that the solid electrolyte only needs to be disposed at least between the positive and negative electrode layers. That is, the solid electrolyte can also exist around the positive and / or negative electrode layers, extending outwards from between them. Specific examples of solid electrolytes include lithium phosphate compounds with a NASICON structure, oxides with a perovskite structure, oxides with garnet-type or garnet-like structures, and oxide glass-ceramic lithium-ion conductors. 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 Ti, Ge, Al, Ga and 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 0.35TiO3, etc. As an example of oxides with garnet-type or garnet-like structures, Li7La3Zr2O can be cited. 12 For example, as oxide glass-ceramic lithium-ion conductors, phosphate compounds (LATP) whose constituent elements include lithium, aluminum, and titanium, and phosphate compounds (LAGP) whose constituent elements include lithium, aluminum, and germanium can be used.

[0041] It should be noted that examples of solid electrolytes capable of conducting sodium ions include sodium-containing phosphate compounds with a NASICON structure, oxides with a perovskite structure, and oxides with garnet-type or garnet-like structures. For example, Na... x M y (PO4)3 (1≤x≤2, 1≤y≤2, M is at least one selected from the group consisting of Ti, Ge, Al, Ga and Zr).

[0042] Solid electrolytes may also include sintering aids. The sintering aids included in the solid electrolyte may, for example, be selected from the same materials that may be included in the positive / negative electrode layers.

[0043] (End face electrode)

[0044] Solid-state batteries typically include end-face electrodes. Specifically, these end-face electrodes are positioned opposite the end faces of the battery element. More specifically, on the end-face regions of the opposing battery elements, there are end-face electrodes on the positive electrode side connected to the positive electrode layer and end-face electrodes on the negative electrode side connected to the negative electrode layer. More specifically, the end-face electrode on the positive electrode layer side is configured to engage with the end of the positive electrode layer, specifically a lead-out formed at the end of the positive electrode layer. Similarly, the end-face electrode on the negative electrode layer side is configured to engage with the end of the negative electrode layer, specifically a lead-out formed at the end of the negative electrode layer.

[0045] In a preferred embodiment, the end-face electrode is preferably made of glass or glass-ceramic, from the angle of joining the lead-out portion of the electrode layer. Furthermore, the end-face electrode is preferably made of a material with high conductivity. While not particularly limited in its specific material, examples include at least one selected from the group consisting of silver, gold, platinum, aluminum, copper, tin, and nickel. By using a metallic material for the end-face electrode, moisture ingress from the end-face electrode can be suppressed. The thickness of the end-face electrode is not particularly limited; for example, it can be 0.01 μm or more and 1 mm or less, particularly 1 μm or more and 100 μm or less.

[0046] (Lower surface electrode)

[0047] Solid-state batteries may also have a lower surface electrode on the lower surface side of the battery element, which is connected to the aforementioned end-face electrode. The lower surface electrode may be configured such that one side is connected to the end-face electrode, and the other side protrudes from the surface of the solid-state battery. In this case, the solid-state battery can be mounted on an electronic substrate via the lower surface electrode. The lower surface electrode is preferably made of a material with high conductivity. While the specific material of the lower surface electrode is not particularly limited, from the perspective of conductivity, materials similar to the conductive metals exemplified as the specific material of the end-face electrode can be used. By using a metallic material for the lower surface electrode, moisture ingress from the lower surface electrode can be suppressed.

[0048] (Overlay)

[0049] The cover layer includes at least one barrier layer. Preferably, the cover layer also includes one or more layers selected from the group consisting of a buffer layer and an impact-resistant layer. The cover layer is configured as described above to cover the battery element with end-face electrodes. Specifically, the cover layer is configured to cover the portion of the battery element with end-face electrodes except for the connection portion with the lower surface electrode. Furthermore, the cover layer is configured to cover the surface of the battery element with end-face electrodes in such a way that the lead-out portion of the electrode layer can engage with the end-face electrode. That is, the cover layer is disposed on the outer surface of the end-face electrode at the location where the end-face electrode is located, rather than on the inner surface of the end-face electrode opposite to the battery element. In this configuration, the barrier layer included in the cover layer, as described later, has the function of preventing the permeation of gases such as water vapor, thus preventing the entry of gases such as water vapor.

[0050] When the covering layer includes an impact-resistant layer, it is preferable to place the impact-resistant layer as the outermost layer from the perspective of external impact resistance and reducing deformation of the device. Furthermore, alternating the buffer layer and the barrier layer provides further flexibility and pinhole prevention, improving water vapor permeability. In other words, by arranging the buffer layer and the barrier layer adjacent to each other, further flexibility and pinhole prevention can be achieved.

[0051] A barrier layer is a layer used to prevent the permeation of gases such as water vapor. The thickness of the barrier layer can be, for example, 10 nm or more and 100 μm or less, preferably 100 nm or more and 10 μm or less. The barrier layer has a thickness of 1.0 × 10⁻⁶. -2 g / (m 2 · days or less, preferably 1×10 - 4 g / (m 2 (days) or more and 8×10 -3 g / (m 2 • less than 1 day, more preferably 1×10 -4 g / (m 2 (days) or more and 8×10-4 g / (m 2 Water vapor transmission rate below 1000 m (days). For example, the water vapor transmission rate of the barrier layer is 4 × 10⁻⁶. -4 g / (m 2 ·sky).

[0052] When the covering layer includes two or more barrier layers, the water vapor transmission rate of each of the two or more barrier layers can also be within the above-mentioned range independently. In this specification, "water vapor transmission rate" refers to the transmission rate obtained using a gas transmission rate measuring device manufactured by ADVANCE RIKO (Stock) Co., Ltd., model GTms-1, under measurement conditions of 40°C, 90% RH, and a pressure difference of 1 atm.

[0053] The barrier layer can be non-conductive. Specifically, the barrier layer has a 1.0 × 10⁻⁶ characteristic layer. 6 Ω / sq. or higher, preferably 1.0×10 8 Surface resistivity of Ω / sq. or higher. In cases where the capping layer comprises two or more barrier layers, the surface resistivity of each or more barrier layer may also be within the above range independently. In this specification, "surface resistivity" refers to the value obtained by measuring a 0.1 mm thick sample using an MCP-HT450 manufactured by Mitsubishi Chemical Analytech at 25°C.

[0054] Considering the impact on external semiconductor components, the barrier layer is preferably a layer that prevents alkali metal ions such as Li ions from permeating. Examples of materials constituting such a barrier layer include nitride films and oxynitride films. Nitride films and oxynitride films are preferably films made of silicon or aluminum, and silicon nitride (SiN) films are more preferably used for both. t ) and silicon oxynitride (SiN) t O u (t and u are values ​​greater than 0). From the perspective of preventing peeling and cracking caused by deformation due to external forces, silicon oxynitride films are preferred.

[0055] As a barrier layer, a silicon oxynitride film with a refractive index of 1.7 or higher (particularly 1.7 or higher and 2.0 or lower) is more preferred, as it suppresses the oxygen ratio to a low level (setting the value of u to a low level). Other materials constituting the barrier layer can be ceramic materials such as low-melting-point glass, or clay films (Claist) as viscosity materials. Low-melting-point glass refers to bismuth, lead, boron, and vanadium-based glasses, indicating materials with a glass transition temperature of 500°C or lower. Clay films are clay-like layered compounds, each having a refractive index of 1.0 × 10⁻⁶. -2 g / (m 2 · days or less, preferably 1×10 -4 g / (m2 (days) or more and 8×10 -3 g / (m 2 • less than 1 day, more preferably 1×10 -4 g / (m 2 (days) or more and 8×10 -4 g / (m 2 Water vapor transmission rate below 1 day.

[0056] The buffer layer is used to allow the cover layer to follow the expansion and contraction of the solid-state battery during charging / discharging, and it is also used to prevent damage to the barrier layer. By placing the buffer layer in direct contact with the barrier layer, it is possible to prevent damage to the barrier layer while allowing the cover layer to follow the expansion and contraction during charging / discharging, resulting in more complete and long-term gas barrier properties.

[0057] The buffer layer can be non-conductive. Specifically, the buffer layer can have a surface resistivity within the same range as the barrier layer. When the cover layer includes two or more buffer layers, the surface resistivity of each or more buffer layers can also be independently within the aforementioned range.

[0058] The materials used to construct the buffer layer are not particularly limited, as long as the buffer layer itself can expand and contract with the solid-state battery during charging / discharging. Examples of materials that can be used to construct the buffer layer include polyimide resin, polyimide silicone resin, silicone resin, polyamide resin, epoxy resin, and rubber. The thickness of the buffer layer is typically, for example, 1 μm or more and 1 mm or less, and particularly 10 μm or more and 500 μm or less.

[0059] The shock-resistant layer is used to prevent damage caused by thermal shock during the reflow soldering of solid-state batteries and physical impact during the handling of solid-state batteries. By configuring the shock-resistant layer as the outermost layer, it is possible to prevent damage to the barrier layer while allowing the cover layer to follow the expansion and contraction during charging / discharging, resulting in more complete and long-term gas barrier properties.

[0060] The impact-resistant layer can be non-conductive. Specifically, the impact-resistant layer can have a surface resistivity within the same range as the barrier layer. There are no particular limitations on the constituent materials of the impact-resistant layer; for example, molding resin composed of resin and filler can be used. As the resin, for example, the same resin exemplified as a constituent material of the buffer layer can be used. As the filler, for example, silica, alumina, SiC (silicon carbide), BN (boron nitride), etc., can be used. A preferred constituent material of the impact-resistant layer is a material obtained by mixing silica with epoxy resin. The thickness of the impact-resistant layer is set such that the expansion relative to the expansion displacement during solid-state battery charging can be controlled to be less than 10%. The thickness of the impact-resistant layer can be, for example, more than 1 μm and less than 1 mm, and particularly more than 10 μm and less than 500 μm.

[0061] [Characteristics of the solid-state battery of the present invention]

[0062] Based on the basic structure of a solid-state battery, the following describes the characteristic features of a solid-state battery according to an embodiment of the present invention.

[0063] The inventors of this application have conducted in-depth research on solutions that can simultaneously ensure contact between the electrode layer and the end-face electrode and suppress damage to the end face of the battery element. As a result of this research, the inventors of this application have conceived of a novel method of providing an insulating buffer layer between the aforementioned cover layer (the layer configured to cover the battery element with the end-face electrode) and the battery element, and of configuring this insulating buffer layer in a distinctive manner.

[0064] Specifically, the inventors of this application came up with the invention based on the technical concept that "the insulating buffer layer positioned between the battery element and the end electrode does not necessarily need to cover the entire area where the battery element and the end electrode are facing each other."

[0065] The term "end-face electrode configured to face the end face of the battery element" as used in this specification refers to an end-face electrode that faces the end face of the battery element and is separated from it by a clamping component (equivalent to an insulating buffer layer). The term "covering layer configured to cover the battery element with end-face electrode" as used in this specification refers to a covering layer configured to cover both (1) the surface of the end-face electrode disposed on the battery element and (2) the surface of the battery element without end-face electrode.

[0066] The term "insulating buffer layer" as used in this specification refers to a layer that is both insulating and has a buffering function. In a broad sense, "an insulating buffer layer positioned between the cover layer and the battery element and surrounding the battery element" refers to an insulating buffer layer sandwiched between the cover layer and the battery element and surrounding the battery element in contact with it. In a narrow sense, it refers to an insulating buffer layer sandwiched between the cover layer and the battery element, where one side of the main surface is always in contact with the battery element, while the other side's main surface is sometimes in contact with the cover layer and sometimes not.

[0067] The term "end-face electrode opposing region of the battery element" as used in this specification refers to the region on the end face of the battery element that is positioned opposite the end-face electrode. The term "insulating buffer layer sandwiched between the battery element and the end-face electrode and discontinuously disposed" as used in this specification broadly refers to the insulating buffer layer being discontinuously disposed between the battery element and the end-face electrode; narrowly refers to a portion between the battery element and the end-face electrode where an insulating buffer layer is disposed and a portion where no insulating buffer layer is disposed.

[0068] Hereinafter, the feature portions of a solid-state battery according to an embodiment of the present invention will be specifically described with reference to the accompanying drawings. Figure 1 It is a schematic representation of from Figure 2 A cross-sectional view of a solid-state battery according to an embodiment of the present invention when viewed in the X-X' direction. Figure 2 This is a schematic perspective view of a solid-state battery according to an embodiment of the present invention.

[0069] like Figure 1 and Figure 2 As shown, an embodiment of the present invention relates to a solid-state battery 1000 comprising a battery element 100, a terminal electrode 300, a cover layer 400, and a lower surface electrode 500. As described above, the battery element 100 comprises a positive electrode layer 10A, a negative electrode layer 10B, and a solid electrolyte layer 20 between the positive electrode layer 10A and the negative electrode layer 10B. The terminal electrode 300 is configured to face the terminal surface 101 of the battery element 100. The cover layer 400 is configured to cover the battery element 100 having the terminal electrode 300. The lower surface electrode 500 is connected to the terminal electrode 300 on the lower surface side of the battery element 100. The lower surface electrode 500 is configured such that one side is connected to the terminal electrode 300, and the other side is exposed to the outside from the surface of the solid-state battery 1000.

[0070] Furthermore, in one embodiment of the present invention, the solid-state battery 1000 also includes an insulating buffer layer 200. This insulating buffer layer 200 is a layer positioned between the cover layer 400 and the battery element 100 and surrounding the battery element 100.

[0071] As an example, such as Figure 1 and Figure 2As shown, the battery element 100 can have a generally cuboid shape. In this case, the "insulating buffer layer 200 surrounding the battery element 100" is equivalent to a layer configured to directly face the upper surface, lower surface and side surface of the end face 101 of the battery element 100 which has a generally cuboid shape.

[0072] As described above, the insulating buffer layer 200, being both insulating and buffering, can alleviate the stress caused by the expansion and contraction of the battery element 100 while simultaneously accommodating the expanding and contracting battery element 100 as a whole, as will be described in detail below. This prevents direct contact between the expanding and contracting battery element 100 and the cover layer 400 and the end electrode 300. Consequently, damage to the end face of the battery element can be prevented. Furthermore, damage to the end face 101 of the battery element 100, formed by the upper surface, lower surface, and side surfaces, can be suppressed as a whole.

[0073] In this configuration, in one embodiment of the present invention, based on the above-described technical concept, an insulating buffer layer 200 positioned on the side of the end electrode opposing region 102 of the battery element 100 is sandwiched between the battery element 100 and the end electrode 300 and is provided intermittently. This is a technical feature of the present invention.

[0074] Based on this technical feature, on the electrode-opposing region 102 side of the end face 101 of the battery element 100, an insulating buffer layer 200 is intermittently sandwiched between the battery element 100 and the end face electrode 300. Therefore, as... Figure 1 As shown, on the side of the end face electrode opposing region 102, (1) an area where the insulating buffer layer 200 is positioned between the battery element 100 and the end face electrode 300 and (2) an area where the insulating buffer layer 200 is not positioned between the battery element 100 and the end face electrode 300 are formed.

[0075] That is, in the case of (1) above, by positioning the insulating buffer layer 200, an opposing region A in which the battery element 100 and the insulating buffer layer 200 directly face each other can be formed between the battery element 100 and the end face electrode 300.

[0076] On the other hand, in the case of (2) above, by means of the unpositioned insulating buffer layer 200, a non-opposite region B in which the battery element 100 and the insulating buffer layer 200 are not opposite each other can be formed between the battery element 100 and the end face electrode 300.

[0077] Here, during the charging and discharging of the battery, the electrode layer 10 (positive electrode layer 10A / negative electrode layer 10B) expands and contracts, and the battery element 100, which contains the electrode layer 10, may also expand and contract accordingly. Due to the stress caused by such expansion and contraction, the cover layer 400 may peel off from the battery element 100 with the end face electrode 300, damaging the end face of the battery element 100. Considering the surface area of ​​the battery element, particularly the end face electrode opposing region 102 of the battery element 100, the stress caused by the expansion and contraction of the battery element 100 may cause the end face electrode 300 to peel off from the battery element 100.

[0078] Regarding this, in region A, the battery element 100 and the end electrode 300 are directly opposite each other. This means that the battery element 100 and the end electrode 300 are not directly opposite each other. Therefore, in region A, direct contact between the battery element 100 and the end electrode 300 is avoided due to expansion and contraction. Furthermore, the insulating buffer layer 200 can utilize its buffering properties to both alleviate the stress caused by the expansion and contraction of the battery element 100 during charging and discharging, and to receive the expanding and contracting battery element 100. That is, the insulating buffer layer 200 can function as a "stress-relieving layer" to alleviate the stress caused by the expansion and contraction of the battery element 100 during charging and discharging.

[0079] As can be seen from the above, it is possible to appropriately prevent the end face electrode 300 from peeling off from the end face electrode opposing region 102. As a result, it is possible to appropriately prevent damage to the end face electrode opposing region 102 in the end face of the battery element 100.

[0080] In region B, the battery element 100 and the insulating buffer layer 200 are not aligned between the battery element 100 and the end face electrode 300. This means that the battery element 100 and the end face electrode 300 are directly aligned. In region B, since the end face of the battery element 100 and the end face electrode 300 are directly aligned, by configuring the electrode layer 10 to be positioned at this directly aligned location, the electrode layer 10 and the end face electrode 300 can be directly aligned.

[0081] Therefore, the electrode layer 10, specifically the lead-out end of the electrode layer 10, can contact the end face electrode 300. As a result, poor contact between the lead-out end of the electrode layer 10 and the end face electrode 300 is avoided, thereby ensuring the electrical connection for properly carrying out the charging and discharging of the solid-state battery 1000.

[0082] On the other hand, in the area other than the end-face electrode opposing region 102 on the end face of the battery element 100, that is, in the region 103 of the battery element 100 that is not opposed to the end-face electrode, since there is no end-face electrode 300, this region 103 can be opposed to the cover layer 400 through the insulating buffer layer 200. In other words, the insulating buffer layer 200 is sandwiched between the region 103 that is not opposed to the end-face electrode and the cover layer 400.

[0083] The presence of this insulating buffer layer 200 prevents the expanding and contracting battery element 100 located in the region 103 not opposite the end face electrode from directly contacting the cover layer 400. Furthermore, the insulating buffer layer 200, by utilizing its buffering properties, can both alleviate the stress caused by the expansion and contraction of the battery element 100 located in region 103 and accommodate the expanding and contracting battery element 100. Thus, the cover layer 400 can be appropriately prevented from peeling off from the region 103 not opposite the end face electrode. Consequently, damage to the region 103 of the end face of the battery element 100 not opposite the end face electrode can also be appropriately prevented.

[0084] As can be seen from the above, according to an embodiment of the present invention, damage to the end face 101 of the battery element 100 can be suppressed as a whole, while also ensuring appropriate contact between the electrode layer 10 and the end face electrode 300.

[0085] It should be noted that the present invention preferably adopts the following method.

[0086] Firstly, in one embodiment, the insulating buffer layer 200 is preferably composed of at least one material (equivalent to a solid lubricant) selected from the group consisting of boron nitride, molybdenum sulfide, and tungsten sulfide.

[0087] Such a material is an insulating material with a heat resistance temperature of 300 degrees Celsius or higher and 900 degrees Celsius or lower, and it does not oxidize even under these high-temperature conditions, maintaining a low coefficient of friction (μ) of less than 0.2 in the atmosphere. Therefore, even if the solid battery 1000 is manufactured by a sintering process at a high temperature (200 degrees Celsius) as described below, it is possible to adequately ensure (1) the mitigation of stress caused by the expansion and contraction of the battery element 100 and (2) the insulation between the battery element 100 and the cover layer 400.

[0088] In one embodiment, the insulating buffer layer 200 is preferably configured to at least contact the battery element 100 (see reference). Figure 1 ).

[0089] As described above, the insulating buffer layer 200 is a layer positioned between the cover layer 400 and the battery element 100 and surrounding the battery element 100. In this regard, from the perspective that the insulating buffer layer 200 can appropriately and directly receive the expanding and contracting battery element 100 while flexing, it is preferable that the end face 101 of the battery element 1200, i.e., the contour region forming the end face 101, is in direct contact with the insulating buffer layer 200.

[0090] More specifically, as described above, the end face 101 of the battery element 100 is composed of an end face electrode opposing region 102 and a region 103 not opposing the end face electrodes. Preferably, either region 102 or region 103 is in direct contact with the insulating buffer layer 200. Thus, the end face 101 of the battery element 100, which expands and contracts, can be appropriately and directly received by the insulating buffer layer 200 as a whole.

[0091] Furthermore, in the region 103 not opposite the end face electrode, it is more preferable that the insulating buffer layer 200 is configured to contact not only the battery element 100 but also the cover layer 400. Specifically, it is more preferable that, in addition to one main surface of the insulating buffer layer 200 being in direct contact with the region 103 of the battery element 100 not opposite the end face electrode, the other main surface of the insulating buffer layer 200 is also in direct contact with the cover layer 400.

[0092] By adopting this configuration, the insulating buffer layer 200 can directly receive not only the expanding and contracting battery element 100, but also the cover layer 400. As a result, not only can the peeling of the cover layer 400 from the area 103 opposite to the end face electrode be properly prevented due to the expansion and contraction of the electrode layer 10, but also the transmission of external pressure, impact, etc., to the cover layer 400 and subsequently to the battery element 100 can be properly prevented.

[0093] In one embodiment, preferably, opposing regions A, where the battery element 100 and the insulating buffer layer 200 directly face each other, and non-opposing regions B, where the battery element 100 and the insulating buffer layer 200 are not facing each other, are alternately formed between the battery element 100 and the end electrode 300 (see reference). Figure 1 ).

[0094] As described above, the presence of opposing region A can appropriately prevent the end electrode 300 from peeling off from the end electrode opposing region 102. The presence of opposing region B allows the end electrode opposing region 102 of the battery element 100 to contact the end electrode 300.

[0095] Here, considering the end-face electrode opposing region 102, which is a component of the end face 101 of the battery element 100, if the opposing region A where the battery element 100 and the insulating buffer layer 200 directly face each other is concentrated in a specified region, it is difficult to ensure that the end-face electrode 300 is peeled off in the specified region, and thus it is difficult to ensure that the battery element 100 and the end-face electrode 300 are in full contact.

[0096] On the other hand, when considering the end electrode opposing region 102 of the battery element 100, if the non-opposing region B of the battery element 100 and the insulating buffer layer 200 are concentrated in a specified region, it is possible to properly ensure that the battery element 100 and the end electrode 300 are in contact in the specified region, and it is difficult to avoid the end electrode 300 peeling off.

[0097] In view of the above points, it is preferable to alternately form the opposing region A and the non-opposing region B as described above. Therefore, when considering the opposing region 102 of the end-face electrode, it is possible to appropriately avoid the concentration of areas where "it is easy to prevent the end-face electrode 300 from peeling off" in a designated location, while areas where "it is easy to ensure contact between the battery element 100 and the end-face electrode 300" are concentrated in other locations besides the designated location. Thus, a balanced approach can be taken to "prevent the end-face electrode 300 from peeling off" and "ensure contact between the battery element 100 and the end-face electrode 300".

[0098] In one embodiment, preferably in region B (the non-opposed region between battery element 100α and end electrode 300α where battery element 100α and insulating buffer layer 200α are not directly opposite each other), only electrode layer 10α and end electrode 300α are directly opposite each other (see reference). Figure 3 and Figure 4 ).

[0099] Figure 3 It is a schematic representation of from Figure 4 A cross-sectional view of a solid-state battery according to an embodiment of the present invention when viewed in the Y-Y' direction. Figure 4 This is a partial perspective view schematically illustrating a solid-state battery according to an embodiment of the present invention. As described above, the presence of the opposing region A appropriately prevents the end electrode 300α from peeling off from the end electrode opposing region 102α. The presence of the opposing region B allows the end electrode opposing region 102α of the battery element 100α to contact the end electrode 300α.

[0100] In region B, where both the electrode layer 10α and the end-face electrode 300α are opposed, the portion where the solid electrolyte layer 20α and the end-face electrode 300α are opposed may not function as an electrical connection for charging and discharging the solid-state battery 1000α. Therefore, by adopting a configuration in region B where only the electrode layer 10α and the end-face electrode 300α are directly opposed, this inactive portion can be substantially eliminated, making region B the minimum required size. This allows for more efficient formation of the electrical connection for charging and discharging the solid-state battery 1000α.

[0101] Furthermore, in this case, on the side of the end-face electrode opposing region 102α of the battery element 100α, since region B can be made to the required minimum extent, the extent of region A (the opposing region between the battery element 100α and the end-face electrode 300α where the battery element 100α and the insulating buffer layer 200α directly face each other) can be relatively larger. As a result, since the area that can "prevent peeling of the end-face electrode 300α" can be larger, the area that can prevent damage to the end face 101α of the battery element 100 at the end-face electrode opposing region 102α can be made larger.

[0102] [Method for manufacturing a solid-state battery according to the present invention]

[0103] The following describes a method for manufacturing a solid-state battery according to an embodiment of the present invention.

[0104] One embodiment of the present invention relates to a solid-state battery that can be manufactured primarily using a green sheet method. In one embodiment, the solid-state battery according to one embodiment of the present invention can be finally manufactured after forming a predetermined laminate using the green sheet method. It should be noted that the following description is based on this method, but is not limited thereto; the predetermined laminate can also be formed by screen printing or a combination thereof.

[0105] (The process of forming unfired laminates)

[0106] First, a paste for a solid electrolyte layer, a paste for a positive electrode material layer, a paste for a positive electrode current collector layer, a paste for a negative electrode material layer, a paste for a negative electrode current collector layer, a paste for an insulating part, and a paste for a protective layer are applied to each substrate (e.g., PET film).

[0107] Each paste can be prepared by wet mixing a specified constituent material of each layer with an organic carrier obtained by dissolving an organic material in a solvent. The specified constituent material of each layer is appropriately selected from the group consisting of a positive electrode active material, a negative electrode active material, a conductive material, a solid electrolyte material, an insulating material, and a sintering aid. For example, the paste for the positive electrode material layer includes a positive electrode active material, a conductive material, a solid electrolyte material, an organic material, and a solvent. For example, the paste for the negative electrode material layer includes a negative electrode active material, a conductive material, a solid electrolyte material, an organic material, and a solvent. For example, at least one of the following can be selected from the group consisting of silver, palladium, gold, platinum, aluminum, copper, and nickel: For example, the paste for the solid electrolyte layer includes a solid electrolyte material, a sintering aid, an organic material, and a solvent. For example, the paste for the protective layer includes an insulating material, an organic material, and a solvent. For example, the paste for the insulating portion includes an insulating material, an organic material, and a solvent.

[0108] Wet mixing can utilize media, specifically ball milling or viscomilling. Alternatively, wet mixing methods without media can be used, such as sand milling, high-pressure homogenizers, or kneading dispersion.

[0109] A paste for a specified solid electrolyte layer can be prepared by wet mixing a specified solid electrolyte material, a sintering aid, and an organic carrier obtained by dissolving an organic material in a solvent. It should be noted that, as mentioned above, examples of solid electrolyte materials include lithium phosphate compounds with a NASICON structure, oxides with a perovskite structure, and oxides with garnet-type or garnet-like structures. 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 Ti, Ge, Al, Ga and 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 wait.

[0110] The positive electrode active material included in the paste for the positive electrode material layer is, for example, selected from at least one of the following groups: lithium phosphate compound having a NASICON-type structure, lithium phosphate compound having an olivine-type structure, lithium-containing layered oxide, and lithium-containing oxide having a spinel-type structure.

[0111] The insulating material included in the paste for insulating parts may be, for example, composed of glass materials, ceramic materials, etc. The insulating material included in the paste for protective layers is preferably, for example, at least one selected from the group consisting of glass materials, ceramic materials, thermosetting resin materials, and photocurable resin materials.

[0112] The organic material included in the paste is not particularly limited, and at least one polymeric material selected from the group consisting of polyvinyl alcohol acetal resin, cellulose resin, polyacrylic acid resin, polyurethane resin, polyvinyl acetate resin, and polyvinyl alcohol resin can be used. The solvent is not particularly limited as long as it can dissolve the aforementioned organic material; for example, toluene and / or ethanol can be used.

[0113] The negative electrode active material included in the paste for the negative electrode material layer is, for example, selected from at least one of the following groups: oxides, graphite-lithium compounds, lithium alloys, lithium phosphate compounds having a NASICON-type structure, lithium phosphate compounds having an olivine-type structure, and lithium oxides having a spinel-type structure, wherein the oxide includes at least one element selected from the group consisting of Ti, Si, Sn, Cr, Fe, Nb, and Mo.

[0114] As a sintering aid, it can be at least one selected from the group consisting of lithium oxide, sodium oxide, potassium oxide, boron oxide, and silicon oxide.

[0115] By drying the applied paste on a hot plate heated to 30–50°C, a solid electrolyte layer, a positive electrode layer including a positive electrode material layer, a negative electrode layer including a negative electrode material layer, and a protective layer are formed on a substrate (e.g., a PET film) with a specified thickness.

[0116] Next, each sheet is peeled off from the substrate. After peeling, the sheets of each component of the battery cell unit are stacked sequentially along the lamination direction.

[0117] During this lamination stage, a solid electrolyte sheet or an insulating sheet is screen-printed onto the side region of the electrode sheet. Specifically, the solid electrolyte sheet or insulating sheet is formed in such a way that it surrounds the non-connected portion of the end electrode in the side region of the electrode sheet, except for the portion subsequently connected to the end electrode.

[0118] Next, hot pressing at a specified pressure (e.g., about 50 to about 100 MPa) and subsequent isostatic pressing at a specified pressure (e.g., about 150 to about 300 MPa) are preferably performed. Through the above treatment, the specified unfired laminate can be formed.

[0119] (Coating process for insulating materials)

[0120] After the specified unfired laminate is formed, an insulating material is supplied to the surface of the unfired laminate. Specifically, the insulating material is continuously coated on the surface of the unfired laminate that does not face the subsequently disposed end face electrode. On the other hand, the insulating material is intermittently supplied to the surface of the unfired laminate that faces the subsequently disposed end face electrode.

[0121] The insulating material supplied to the surface of the unfired laminate is preferably a material that has insulating properties, a heat resistance temperature of 300°C or higher and 900°C or lower, and can maintain a low coefficient of friction (μ) of 0.2 or lower in the atmosphere without oxidation even under these high-temperature conditions. For this reason, at least one material selected from the group consisting of boron nitride, molybdenum sulfide, and tungsten sulfide is preferred as the insulating material supplied to the surface of the unfired laminate. Methods for intermittently supplying the insulating material include spraying and intermittent coating. Through the above processing, an unfired laminate with insulating material is obtained, on the surface opposite the end face electrode, on which the insulating material is intermittently coated.

[0122] (Firing process)

[0123] Next, the unfired laminate containing the insulating material is fired. This firing is performed by pressing the unfired laminate containing the insulating material using a heated mold. For example, a mold heated to 100 degrees Celsius or higher and 250 degrees Celsius or lower, such as 200 degrees Celsius, is used as the mold for pressing. Through this process, a fired laminate can be obtained. A single-piece process for the fired laminate can also be performed as needed.

[0124] (End face electrode formation process)

[0125] Next, an end-face electrode is formed on the surface of the sintered laminate in a manner that directly faces the portion to which the insulating material is intermittently supplied. That is, the end-face electrode is formed on the portion to which the insulating material is intermittently supplied. Although not particularly limited, the end-face electrode is preferably made of at least one selected from silver, gold, platinum, aluminum, copper, tin, and nickel.

[0126] Regarding the end-face electrode on the positive electrode side, the positive electrode layer in the sintered laminate can be formed on the exposed side using dry deposition methods such as physical vapor deposition (PVD) and chemical vapor deposition (CVD). Examples of physical vapor deposition (PVD) methods include vacuum evaporation and sputtering (especially ion beam sputtering). Examples of chemical vapor deposition (CVD) methods include thermal CVD and plasma CVD. Similarly, regarding the end-face electrode on the negative electrode side, the negative electrode layer in the sintered laminate can be formed on the exposed side using the aforementioned dry deposition methods.

[0127] Not limited to this, end-face electrodes can be formed by coating the exposed sides of the electrode layer in the sintered laminate with a conductive paste and then sintering. It should be noted that the formation of end-face electrodes on the positive and negative electrode sides can be performed not only after sintering the laminate, but also before or simultaneously with sintering. Furthermore, end-face electrodes can typically be formed using a mask in the above-described method. For example, an ion beam sputtering apparatus can be used to form end-face electrodes on the portion not covered by the mask.

[0128] (The process of forming the lower surface electrode)

[0129] Following the formation of the end face electrode, the lower surface electrode is formed. Specifically, the lower surface electrode on the positive electrode side can be formed, for example, by the aforementioned dry plating method to be electrically connected to the end face electrode on the positive electrode side. Similarly, the lower surface electrode on the negative electrode side can be formed, for example, by the aforementioned dry plating method to be electrically connected to the end face electrode on the negative electrode side.

[0130] Not limited to this, the lower surface electrode on the positive electrode side can be formed by coating a conductive paste and sintering. Similarly, the lower surface electrode on the negative electrode side can be formed by coating a conductive paste and sintering. The lower surface electrode can be formed using a mask in the above methods. For example, the lower surface electrode can be formed in the portion other than the portion covered by the mask using an ion beam sputtering apparatus.

[0131] (The process of forming the capping layer)

[0132] After the lower surface electrode is formed, a coating layer is formed by firing a laminate over the end face electrode. The formation of the coating layer is not limited to after the formation of the lower surface electrode; it can also occur before. Such a coating layer can consist of multiple layers. By forming the coating layer, an encapsulated solid-state battery can be obtained. "Encapsulation" broadly refers to the process of protecting the battery from external environmental influences; narrowly, it refers to the act of forming a coating layer to prevent water vapor from the external environment from entering the solid-state battery.

[0133] There are no particular limitations on the formation method of each layer. For example, the interface layer can be formed by applying an interface layer coating solution and then drying it. The barrier layer can be formed by applying a barrier layer coating solution and then drying it, or it can be formed by the dry plating method described above. The buffer layer can be formed by applying a buffer layer coating solution and then drying it. The impact-resistant layer can be formed by applying an impact-resistant layer coating solution and then drying it. The coating method described above can be implemented by various methods. For example, dip coating, brush coating, blade coating, wire rod coating, spray coating, bead coating, air knife coating, curtain coating, etc. can be mentioned.

[0134] Through the above processing, a solid-state battery according to an embodiment of the present invention can be obtained (see reference). Figure 1 and Figure 2 As described in the section on the characteristics of the solid-state battery of the present invention, the resulting solid-state battery 1000 has an insulating buffer layer 200. This insulating buffer layer 200 is positioned between the cover layer 400 and the battery element 100 and surrounds the end face of the battery element 100. In this configuration, in the resulting solid-state battery 1000, the insulating buffer layer 200, particularly positioned on the side of the end face electrode opposing region 102 of the battery element 100, is sandwiched between the battery element 100 and the end face electrode 300 and is provided intermittently.

[0135] With such an intermittent configuration of the insulating buffer layer 200, on the side of the end face electrode opposing region 102, (1) an area where the insulating buffer layer 200 is positioned between the battery element 100 and the end face electrode 300 and (2) an area where the insulating buffer layer 200 is not positioned between the battery element 100 and the end face electrode 300 are formed.

[0136] In the region where the insulating buffer layer 200 is positioned in (1), the buffering properties of the insulating buffer layer 200 can be used to alleviate the stress caused by the expansion and contraction of the battery element 100 while accommodating the expanding and contracting battery element 100. As a result, peeling of the end face electrode 300 is appropriately avoided, thereby appropriately preventing damage to the end face electrode opposing region 102 in the end face of the battery element 100. On the other hand, in the region where the insulating buffer layer 200 is not positioned in (2), the battery element 100 and the end face electrode 300 can be directly opposed. As a result, the electrode layer 10 can be appropriately ensured to contact the end face electrode 300, and the electrical connection for properly carrying out the charging and discharging of the solid battery 1000 can be ensured.

[0137] Furthermore, in the region 103 that is not opposed to the end face electrode, excluding the end face electrode opposing region 102 which is a component of the end face 101 of the battery element 100, an insulating buffer layer 200 is positioned between this region 103 and the cover layer 400. By functioning as a stress-relieving layer, the insulating buffer layer 200 prevents the cover layer 400 from peeling off from the region 103 that is not opposed to the end face electrode during battery charging and discharging.

[0138] As can be seen from the above, in the obtained solid battery 1000, damage to the end face 101 of the battery element 100 can be suppressed as a whole, while also ensuring that the electrode layer 10 is in contact with the end face electrode 300.

[0139] Example

[0140] The embodiments of the present invention will be described below.

[0141] [Comparative Example]

[0142] (No insulating buffer layer)

[0143] As a solid-state battery, a battery was manufactured having battery elements, end-face electrodes positioned in direct contact with the end faces of the battery elements without an insulating buffer layer (i.e., an insulating component), and a cover layer covering the battery elements with the end-face electrodes. After manufacturing, the solid-state battery was charged and discharged, and then the solid-state battery was ground to check the state of the battery elements and the cover layer. Specifically, it was checked whether the cover layer had peeled off from the battery elements. As a result, it was observed that the cover layer had peeled off from the end faces of the battery elements.

[0144] [Example]

[0145] Example (with insulating buffer layer)

[0146] As a solid-state battery, a battery having a battery element, end-face electrodes positioned opposite the end faces of the battery element, a cover layer covering the battery element with the end-face electrodes, and an insulating buffer layer positioned between the cover layer and the battery element and surrounding the battery element is manufactured. Specifically, in this embodiment, the insulating buffer layer is configured to be intermittently sandwiched between the battery element and the end-face electrodes on the side facing the end faces of the battery element. After manufacturing, the solid-state battery is charged and discharged, and then the solid-state battery is polished to check the state of the battery element and the cover layer. Specifically, it is checked whether the cover layer has peeled off from the battery element.

[0147] As a result, it is known that the peeling of the cover layer from the end face of the battery element is suppressed. Therefore, it is known that in addition to ensuring contact between the electrode layer and the end face electrode through the intermittent configuration of the insulating buffer layer, damage to the end face of the battery element can also be suppressed. That is, it is known that both ensuring contact between the electrode layer and the end face electrode and suppressing damage to the end face of the battery element can be achieved.

[0148] Experimental Example 1

[0149] Specifically, regarding the insulating material between the battery element and the end-face electrode, an insulating material is prepared in which the ratio ([%]) of the formed area of ​​the insulating material to the total area of ​​the electrode layer located on the end face of the battery element (corresponding to the end-face electrode opposing region) is 0.2% (greater than 0.1%). As a result, it is known that the peeling of the cover layer from the end face of the battery element, specifically the end-face electrode opposing region of the battery element, is suppressed.

[0150] Experiment Example 2

[0151] Regarding the insulating material between the battery element and the end electrode, an insulating material was prepared in which the ratio ([%) of the formed area of ​​the insulating material to the total area of ​​the electrode layer located on the end face of the battery element (corresponding to the end electrode opposing region) is 90% (less than 95%). As a result, it is known that the peeling of the cover layer from the end face of the battery element, specifically the end electrode opposing region of the battery element, is suppressed.

[0152] Experimental Example 3

[0153] Regarding the insulating material between the battery element and the end electrode, an insulating material was prepared in which the ratio ([%) of the formed area of ​​the insulating material to the total area of ​​the electrode layer located on the end face of the battery element (corresponding to the end electrode opposing region) is 0.5%. As a result, when the ratio ([%) of the formed area of ​​the insulating material is 0.5%, no peeling of the cover layer from the end face of the battery element, specifically the end electrode opposing region of the battery element, was observed. Furthermore, it can be seen that through appropriate contact between the end face of the battery element, specifically the end electrode opposing region of the battery element and the end electrode, such as... Figure 5 As shown, the voltage-capacity curve of the battery becomes stable after charging and discharging.

[0154] Experiment Example 4

[0155] Regarding the insulating material between the battery element and the end electrode, an insulating material was prepared in which the ratio ([%) of the formed area of ​​the insulating material to the total area ([%)) of the electrode layer located on the end face of the battery element (corresponding to the end electrode opposing region) is 50%. As a result, even with the ratio ([%)) of the formed area of ​​the insulating material being 50%, no peeling of the cover layer from the end face of the battery element, specifically the end electrode opposing region of the battery element, was observed. Furthermore, it can be seen that through appropriate contact between the end face of the battery element, specifically the end electrode opposing region of the battery element, and the end electrode, the cover layer effectively adheres to the electrode structure. Figure 5 Similarly, the voltage-capacity curves of the battery after charging and discharging become stable.

[0156] Experimental Example 5

[0157] Regarding the insulating material between the battery element and the end electrode, an insulating material was prepared in which the ratio ([%) of the formed area of ​​the insulating material to the total area of ​​the electrode layer located on the end face of the battery element (corresponding to the end electrode opposing region) is 75%. As a result, even when the ratio ([%) of the formed area of ​​the insulating material is 0.5%, no peeling of the cover layer from the end face of the battery element, specifically the end electrode opposing region of the battery element, was observed. Furthermore, it can be seen that through appropriate contact between the end face of the battery element, specifically the end electrode opposing region of the battery element, and the end electrode, the cover layer effectively adheres to the electrode structure. Figure 5 Similarly, the voltage-capacity curves of the battery after charging and discharging become stable.

[0158] As can be seen from the above, regarding the insulating material between the battery element and the end electrode, if the ratio of the area formed by the insulating material to the total area of ​​the electrode layer located in the area opposite the end electrode is greater than 0.1% and less than 95%, specifically 0.2% or more and 90% or less, then both "preventing end electrode peeling" and "ensuring contact between the battery element and the end electrode" can be achieved. Furthermore, if the ratio of the area formed by the insulating material is preferably 0.5% or more and 75% or less, then in addition to achieving both "preventing end electrode peeling" and "ensuring contact between the battery element and the end electrode," the voltage-capacity curve after battery charge and discharge is also more stable.

[0159] It should be noted that, in this embodiment, molybdenum sulfide or tungsten sulfide can also be used as the insulating material instead of boron nitride. This is because these materials are insulating, have a heat resistance temperature of 300 degrees Celsius or higher and 900 degrees Celsius or lower, and do not oxidize even under these high-temperature conditions, thus maintaining a low coefficient of friction (μ) of less than 0.2 in the atmosphere.

[0160] The above description illustrates one embodiment of the present invention, but is merely a typical example within the scope of application of the invention. Therefore, the present invention is not limited thereto, and those skilled in the art should readily understand that various modifications can be made.

[0161] Industrial applicability

[0162] The solid-state battery according to one embodiment of the present invention can be used in a wide variety of fields where energy storage is envisioned. The solid-state battery according to one embodiment of the present invention can be used in electrical / information / communication fields using mobile devices such as mobile phones (e.g., mobile phones, smartphones, smartwatches, laptops, digital cameras, activity meters, ARM computers, electronic paper, 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 systems (e.g., various power generation systems, load conditioners, smart grids, home stationary energy storage systems, etc.); medical applications (medical devices such as headphones and hearing aids); pharmaceutical applications (medical management systems, etc.); IoT fields; and space / deep-sea applications (e.g., space probes, underwater research vessels, etc.), etc., but the above are merely illustrative examples.

[0163] Symbol Explanation

[0164] 10, 10α electrode layers

[0165] 10A, 10Aα cathode layer

[0166] 10B, 10Bα negative electrode layer

[0167] 20, 20α solid electrolyte layer

[0168] 100, 100α battery elements

[0169] End faces of 101 and 101α battery elements

[0170] Electrode-opposing regions on the end faces of 102 and 102α battery elements

[0171] The area on the end face of the 103 and 103α battery elements that is not opposite to the electrode.

[0172] 200, 200α insulating buffer layer

[0173] 300, 300α end face electrodes

[0174] 400, 400α capping layer

[0175] 500, 500α lower surface electrode

[0176] 1000, 1000α solid-state batteries

[0177] A. The battery element and the end electrode are directly opposite each other, with the battery element and the insulating buffer layer facing each other.

[0178] Set area

[0179] B. The battery element and the insulating buffer layer are not aligned.

[0180] Set area.

Claims

1. A solid-state battery, comprising: A battery element has a positive electrode layer, a negative electrode layer, and a solid electrolyte layer between the positive electrode layer and the negative electrode layer; The end electrode is configured to face the end face of the battery element; A cover layer is configured to cover the battery element having the end face electrodes; as well as An insulating buffer layer is configured to be located between the cover layer and the battery element and to surround the battery element. On the side of the end face electrode opposite region of the end face of the battery element, the insulating buffer layer is sandwiched between the battery element and the end face electrode and is provided intermittently.

2. The solid-state battery according to claim 1, wherein, The insulating buffer layer is configured to be in contact with at least the battery element.

3. The solid-state battery according to claim 1 or 2, wherein, An opposing region and a non-opposing region are formed between the battery element and the end face electrode. The opposing region is the area where the battery element and the insulating buffer layer are directly opposite each other, and the non-opposing region is the area where the battery element and the insulating buffer layer are not opposite each other.

4. The solid-state battery according to claim 3, wherein, Between the battery element and the end face electrode, the opposing region and the non-opposing region are alternately formed.

5. The solid-state battery according to any one of claims 1 to 4, wherein, The portion of the electrode layer formed by intermittently forming the insulating buffer layer, which is at least one of the positive electrode layer and the negative electrode layer, can directly face the end face electrode.

6. The solid-state battery according to claim 5, wherein, Only the electrode layer is directly opposite the end face electrode.

7. The solid-state battery according to any one of claims 1 to 6, wherein, The battery element has a generally rectangular parallelepiped shape. The insulating buffer layer is configured to directly face the upper surface, lower surface, and side surface of the end face of the battery element, which is generally rectangular in shape.

8. The solid-state battery according to any one of claims 1 to 7, wherein, Between the battery element and the end face electrode, the ratio of the area of ​​the insulating buffer layer formed to the total area of ​​the electrode layer located on the end face of the battery element is greater than 0.1% and less than 95%.

9. The solid-state battery according to claim 8, wherein, The ratio is above 0.5% and below 75%.

10. The solid-state battery according to any one of claims 1 to 9, wherein, The heat resistance temperature of the insulating buffer layer is above 300 degrees Celsius.

11. The solid-state battery according to any one of claims 1 to 10, wherein, The insulating buffer layer is made of at least one material selected from the group consisting of boron nitride, molybdenum sulfide and tungsten sulfide.

12. The solid-state battery according to any one of claims 1 to 11, wherein, The insulating buffer layer is a stress-relieving layer.

13. The solid-state battery according to any one of claims 1 to 12, wherein, The covering layer has a barrier layer that prevents water vapor from passing through.

14. The solid-state battery according to claim 13, wherein, The barrier layer has a size of 1.0 × 10⁻⁶. -2 g / (m 2 Water vapor transmission rate below 1 day.

15. The solid-state battery according to any one of claims 1 to 14, wherein, The positive electrode layer and the negative electrode layer are layers capable of inserting and de-intercalating lithium ions.

16. A method for manufacturing a solid-state battery, comprising: In step (i), a positive electrode layer sheet, a solid electrolyte layer sheet, and a negative electrode layer sheet are stacked along the stacking direction to form an unburned laminate. Step (ii) involves supplying insulating material to the surface of the unburned laminate; Step (iii) involves firing the unfired laminate containing the insulating material to form a fired laminate; Step (iv): an end face electrode is disposed on the surface of the sintered laminate; as well as Step (v) involves forming a coating layer by covering the fired laminate with the said end-face electrodes. In step (ii), the insulating material is intermittently supplied to the surface of the unfired laminate that will be opposite the end face electrode.

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