Solid-state battery cell, method for manufacturing a solid-state battery cell

Abstract

Provided is a solid-state battery cell capable of discharging heat generated in a positive electrode to the outside and a method for manufacturing the same. The solid-state battery cell (1) includes: an electrode assembly (10) including a positive electrode, a separator, and a negative electrode; and an insulating layer (20) disposed so as to surround the outer periphery of the electrode assembly (10), wherein the insulating layer (20) includes acicular alumina (30).

Description

Technical Field

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

[0002] In a solid-state battery cell, an insulating layer is provided around the outer periphery of the electrode assembly to ensure the insulation of the electrode assembly, which includes the positive electrode, the separator, and the negative electrode (see, for example, Patent Document 1).

[0003] Prior technology literature

[0004] [Patent Documents]

[0005] Patent Document 1: Japanese Patent Application Publication No. 2023-47083 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] When the positive electrode of the electrode assembly heats up during charging and discharging, the electrode assembly, which is surrounded by an insulating layer, easily accumulates heat. When the electrode assembly accumulates heat, it may deteriorate under the influence of this heat.

[0008] This application aims to solve the above-mentioned problems and its purpose is to provide a solid-state battery cell and a method for manufacturing a solid-state battery cell that can release the heat generated at the positive electrode to the outside, which helps to stabilize battery performance and even improve energy efficiency.

[0009] Solution for solving the problem

[0010] To achieve the above objectives, the present invention provides the following solutions.

[0011] [1] A solid-state battery cell comprising: an electrode assembly including a positive electrode, a separator, and a negative electrode; and an insulating layer disposed around the outer periphery of the electrode assembly, wherein,

[0012] The insulating layer comprises needle-shaped aluminum oxide.

[0013] According to the above scheme, the needle-shaped alumina are arranged closely together within the insulating layer, easily forming a thermal path based on the needle-shaped alumina. Therefore, the heat generated in the electrode assembly during charging and discharging can be released to the outside of the solid-state battery cell via the needle-shaped alumina. Since the needle-shaped alumina can conduct heat along its length, its effect of releasing heat generated in the electrode assembly during charging and discharging to the outside of the solid-state battery cell is superior to that of spherical alumina.

[0014] [2] According to the solid-state battery cell described in [1], wherein,

[0015] The needle-shaped alumina is oriented from the interface between the electrode assembly and the insulating layer toward the outer surface of the insulating layer.

[0016] According to the above scheme, by orienting the needle-shaped alumina from the interface between the electrode assembly and the insulating layer toward the outer surface of the insulating layer, the heat generated by the electrode assembly can be efficiently released to the outside of the solid-state battery cell through the needle-shaped alumina contained in the insulating layer.

[0017] [3] According to the solid-state battery cell described in [1] or [2], wherein,

[0018] The content of needle-shaped alumina relative to the total mass of the insulating layer is 20% by mass or more.

[0019] According to the above scheme, the needle-shaped alumina are arranged close to each other within the insulating layer, which makes it easy to form a thermal path based on the needle-shaped alumina.

[0020] [4] A solid-state battery cell according to any one of [1] to [3], wherein,

[0021] The needle-shaped alumina has a length of 50 μm or more and an aspect ratio of 100 or more.

[0022] According to the above scheme, the needle-shaped alumina are arranged close to each other within the insulating layer, which makes it easy to form a thermal path based on the needle-shaped alumina.

[0023] [5] A solid-state battery cell according to any one of [1] to [4], wherein,

[0024] The insulating layer comprises spherical aluminum oxide.

[0025] According to the above scheme, spherical alumina fills the spaces between needle-shaped alumina and connects the needle-shaped alumina to each other through the spherical alumina, thus easily forming a thermal pathway based on needle-shaped alumina.

[0026] [6] A method for manufacturing a solid-state battery cell, the solid-state battery cell comprising: an electrode assembly including a positive electrode, a separator, and a negative electrode; and an insulating layer disposed around the outer periphery of the electrode assembly, wherein,

[0027] The method for manufacturing the solid-state battery cell includes an insulating layer forming step, in which an insulating layer is formed by using a die-coating method to cover the outer periphery of the electrode assembly with an insulating composition containing needle-shaped alumina.

[0028] According to the above scheme, the needle-shaped alumina are arranged close to each other in the insulating composition, which makes it easy to form a thermal path based on the needle-shaped alumina. Therefore, an insulating layer can be formed to release the heat generated in the electrode assembly during charging and discharging to the outside of the solid-state battery cell via the needle-shaped alumina.

[0029] [7] According to the manufacturing method of the solid-state battery cell described in [6], wherein,

[0030] In the flow path of the slit die used in the molding process, the flow rate of the insulating component is controlled to slow down from the center of the flow path along its length toward the inner wall surface of the flow path.

[0031] According to the above scheme, within the flow path of the slit die, the flow rate of the insulating component is controlled by the shear stress difference to slow down from the center of the flow path along the inner wall surface, thereby orienting the needle-shaped alumina. As a result, within the flow path of the slit die, the needle-shaped alumina flows along the length of the flow path, thus enabling the needle-shaped alumina contained in the insulating component ejected from the nozzle of the slit die to be supplied to the outer periphery of the electrode assembly in an oriented state along one direction.

[0032] [8] According to the manufacturing method of the solid-state battery cell described in [7], wherein,

[0033] The width of the nozzle of the slit head is greater than 100μm and less than 1000μm.

[0034] According to the above scheme, an insulating layer in which needle-shaped alumina is oriented in one direction can be formed.

[0035] [9] A method for manufacturing a solid-state battery cell according to any one of [6] to [8], wherein,

[0036] The manufacturing method of the solid-state battery cell includes a modulation step for modulating the insulating components.

[0037] The modulation process includes: a first step of mixing insulating material with spherical alumina to obtain a first compound; and a second step of mixing the first compound with needle-shaped alumina to obtain a second compound.

[0038] According to the above scheme, within the insulating composition, the needle-shaped alumina are arranged close to each other, which facilitates the formation of thermal pathways based on the needle-shaped alumina.

[0039]

[10] According to the manufacturing method of the solid-state battery cell described in [9], wherein,

[0040] The needle-shaped alumina has a length of 50 μm or more and an aspect ratio of 100 or more.

[0041] According to the above scheme, within the insulating composition, the needle-shaped alumina are arranged close to each other, which facilitates the formation of thermal pathways based on the needle-shaped alumina.

[0042]

[11] The method for manufacturing a solid-state battery cell according to [9] or

[10] , wherein,

[0043] The spherical alumina has a particle size of 10 nm or more and 5000 nm or less.

[0044] According to the above scheme, within the insulating composition, spherical alumina fills the spaces between needle-shaped alumina and connects the needle-shaped alumina to each other via the spherical alumina, thus easily forming a thermal path based on the needle-shaped alumina.

[0045] Invention Effects

[0046] According to the present invention, a solid-state battery cell capable of releasing heat generated at the positive electrode to the outside and a method for manufacturing the solid-state battery cell are provided. Attached Figure Description

[0047] Figure 1 This is a cross-sectional view of a solid-state battery cell according to an embodiment of the present invention.

[0048] Figure 2 This is a cross-sectional view showing the slit die used in the manufacturing method of a solid-state battery cell according to an embodiment of the present invention.

[0049] Explanation of reference numerals in the attached figures:

[0050] 1 Solid-state battery cell

[0051] 10 Electrode Assembly

[0052] 20 Insulation layer

[0053] 30 Needle-shaped alumina

[0054] 100 Slit Die Head

[0055] 101 flow path

[0056] 102 Spray outlet. Detailed Implementation

[0057] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0058] [Solid-state battery cell]

[0059] Figure 1This is a cross-sectional view showing a solid-state battery cell according to an embodiment of the present invention. It should be noted that the drawings used in the following description sometimes show enlarged portions of features for ease of understanding, and the size ratios of the constituent elements are not limited to the content shown in the drawings.

[0060] like Figure 1 As shown, the solid-state battery cell 1 of this embodiment includes an electrode assembly 10 and an insulating layer 20. The insulating layer 20 is configured to surround the outer periphery of the electrode assembly 10. The insulating layer 20 includes needle-shaped aluminum oxide 30.

[0061] Within the insulating layer 20, needle-shaped alumina 30 is oriented from the interface 10a between the electrode assembly 10 and the insulating layer 20 toward the outer surface 20a of the insulating layer 20 (the side of the insulating layer 20 opposite to the interface 10a). This allows the heat generated by the electrode assembly 10 to be efficiently released to the outside of the solid-state battery cell 1 via the needle-shaped alumina 30 contained in the insulating layer 20.

[0062] The orientation degree of the needle-shaped alumina 30 within the insulating layer 20 is preferably 30% or more, more preferably 60% or more, and even more preferably 80% or more. When the orientation degree of the needle-shaped alumina 30 is at or above the aforementioned lower limit value, the heat generated by the electrode assembly 10 can be efficiently released to the outside of the solid-state battery cell 1 via the needle-shaped alumina 30 contained in the insulating layer 20. Here, the orientation degree of the needle-shaped alumina 30 within the insulating layer 20 refers to the proportion of needle-shaped alumina 30 oriented in the same direction within the insulating layer 20.

[0063] The orientation degree of the needle-shaped alumina 30 within the insulating layer 20 can be determined by X-ray CT measurement, CT scanner measurement, TMA measurement, or orientation tensor analysis.

[0064] The insulating layer 20 may also contain spherical aluminum oxide.

[0065] The electrode assembly 10 has a positive electrode, a negative electrode, and a solid electrolyte layer.

[0066] (positive electrode)

[0067] The positive electrode has a first current collector foil and a positive electrode active material layer containing at least the positive electrode active material.

[0068] The first current collector foil is preferably made of at least one material with high conductivity.

[0069] Materials with high conductivity include, for example, metals or alloys including at least one of the following metallic elements: silver (Ag), palladium (Pd), gold (Au), platinum (Pt), aluminum (Al), chromium (Cr), and nickel (Ni), or nonmetals such as carbon (C). When manufacturing cost is considered in addition to conductivity, aluminum, nickel, or stainless steel are preferred. Moreover, aluminum is less likely to react with the positive electrode active material and the electrolyte. Therefore, when aluminum is used for the first current collector foil, the internal resistance of the battery can be reduced.

[0070] Examples of the shapes of the first current collector foil include foil, plate, mesh, non-woven fabric, and foam. Furthermore, to improve adhesion to the positive electrode active material layer, carbon or similar materials can be deposited on the surface of the first current collector foil, or the surface can be roughened.

[0071] The positive electrode active material layer contains a positive electrode active material that accepts and donates electrons with lithium ions. As a positive electrode active material, any material capable of reversibly releasing and storing lithium ions and transporting electrons is acceptable; there are no particular limitations, and known positive electrode active materials suitable for lithium-ion batteries can be used. Examples include: lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium manganese oxide (LiMn2O4), solid solution oxides (Li2MnO3-LiMO2 (M=Co, Ni, etc.)), lithium-manganese-nickel-cobalt oxides (LiNixMnyCozO2, x+y+z=1), olivine-type lithium phosphorus oxide (LiFePO4), and other composite oxides; conductive polymers such as polyaniline and polypyrrole; sulfides such as Li2S, CuS, Li-Cu-S compounds, TiS2, FeS, MoS2, and Li-Mo-S compounds; mixtures of sulfur and carbon; etc. The positive electrode active material can be composed of one of the above materials alone, or it can be composed of two or more of the above materials.

[0072] The positive electrode active material layer includes an electrolyte that facilitates lithium-ion transfer between the positive electrode active material and the electrolyte. As for the electrolyte, any material with lithium-ion conductivity is acceptable; there are no particular limitations, and materials commonly used in lithium-ion batteries can be used. Examples of electrolytes include sulfide solid electrolyte materials, oxide solid electrolyte materials, halide solid electrolytes, inorganic solid electrolytes such as those containing lithium salts, polymer-based solid electrolytes such as polyethylene oxide, and gel-based solid electrolytes including lithium-containing ionic liquids with lithium-ion conductivity. Among these, sulfide solid electrolyte materials are preferred from the viewpoints of high lithium-ion conductivity, good formability based on stamping, and good interfacial bonding.

[0073] The electrolyte can be composed of one or more of the aforementioned materials. The electrolyte contained in the positive electrode active material layer can be the same material as the electrolyte contained in the negative electrode active material layer and the solid electrolyte layer, or it can be a different material.

[0074] From the viewpoint of improving the conductivity of the positive electrode, the positive electrode active material layer may also include conductive additives. Conductive additives commonly used in lithium-ion batteries can be used as conductive additives. Examples include: carbon blacks such as acetylene black and Ketjen black; carbon fibers; fumed carbon fibers; graphite powder; carbon nanotubes, and other carbon materials. The conductive additive can be composed of one or more of the above materials.

[0075] In addition, the positive electrode active material layer may also include an adhesive that has the function of bonding the positive electrode active materials to each other and to the first current collector foil.

[0076] The first collector foil is gathered at one end of the solid-state battery cell 1 in the width direction.

[0077] The positive electrode active material layer sometimes contains sulfides contained in the solid electrolyte layer in order to connect with the solid electrolyte layer.

[0078] (negative electrode)

[0079] The negative electrode is stacked with a second current collector foil and a negative electrode active material layer containing at least the negative electrode active material.

[0080] The second current collector foil contains at least copper (Cu). The second current collector foil may also contain a material other than copper with high conductivity, similar to the first current collector foil. Examples of materials other than copper with high conductivity include metals or alloys containing at least one of the following metallic elements: silver (Ag), palladium (Pd), gold (Au), platinum (Pt), chromium (Cr), and nickel (Ni), or nonmetals such as carbon (C). When manufacturing cost is considered in addition to conductivity, nickel or stainless steel is preferred as a material other than copper. Furthermore, stainless steel is less likely to react with the positive electrode active material, the negative electrode active material, and the electrolyte. Therefore, using stainless steel for the second current collector foil can reduce the manufacturing cost of the battery.

[0081] Examples of the shapes of the second current collector foil include foil, plate, mesh, non-woven fabric, and foam. Furthermore, to improve adhesion to the negative electrode active material layer, carbon or similar materials can be deposited on the surface of the second current collector foil, or the surface can be roughened.

[0082] The negative electrode active material layer contains a negative electrode active material that accepts and accepts electrons with lithium ions. As a negative electrode active material, any material capable of reversibly releasing and storing lithium ions and capable of electron transport is acceptable; there are no particular limitations, and known negative electrode active materials suitable for lithium-ion batteries can be used. Examples include: carbonaceous materials such as natural graphite, artificial graphite, resin carbon, carbon fiber, activated carbon, hard carbon, and soft carbon; alloy materials mainly composed of tin, tin alloys, silicon, silicon alloys, gallium, gallium alloys, indium, indium alloys, aluminum, and aluminum alloys; conductive polymers such as polyphenylene, polyacetylene, and polypyrrole; metallic lithium; and lithium-titanium composite oxides (e.g., Li4Ti5O). 12 Lithium alloys, etc. These negative electrode active materials can be composed of one or more of the above materials.

[0083] The negative electrode active material layer includes an electrolyte that facilitates the transfer of lithium ions between the negative electrode active material and the electrolyte. As for the electrolyte, it is not particularly limited as long as it has lithium-ion conductivity, and materials commonly used in lithium-ion batteries can be used. Examples of electrolytes include sulfide solid electrolyte materials, oxide solid electrolyte materials, halide solid electrolytes, inorganic solid electrolytes such as those containing lithium salts, polymer-based solid electrolytes such as polyethylene oxide, and gel-based solid electrolytes including lithium salts and lithium-ion conductive ionic liquids. The electrolyte can be composed of one or more of the above materials.

[0084] The electrolyte contained in the negative electrode active material layer can be the same as or different from the electrolyte contained in the positive electrode active material layer and the solid electrolyte layer.

[0085] The negative electrode active material layer may also include conductive additives and binders. There are no particular limitations on these materials; for example, the same materials used for the positive electrode active material layer described above can be used.

[0086] (Solid electrolyte layer)

[0087] The solid electrolyte layer is disposed between the positive electrode active material layer and the negative electrode active material layer.

[0088] As an electrolyte, there are no particular restrictions as long as it possesses lithium-ion conductivity and insulation properties; materials commonly used in lithium-ion batteries can be used. Examples include sulfide solid electrolyte materials, oxide solid electrolyte materials, halide solid electrolytes, inorganic solid electrolytes containing lithium salts, polymer-based solid electrolytes such as polyethylene oxide, and gel-based electrolytes including lithium-ion-conducting ionic liquids. Among these, sulfide solid electrolyte materials are preferred from the viewpoints of high lithium-ion conductivity, good formability based on stamping, and good interfacial bonding.

[0089] There are no particular limitations on the form in which electrolyte materials can be used; for example, particulate form can be used.

[0090] The solid electrolyte layer may also contain adhesives to impart mechanical strength and flexibility.

[0091] The solid electrolyte layer can also be a sheet containing a porous substrate and a solid electrolyte held in that porous substrate. There are no particular limitations on the form of the porous substrate; examples include woven fabrics, nonwoven fabrics, mesh fabrics, porous membranes, extended sheets, and perforated sheets. Among these forms, nonwoven fabrics are preferred from the viewpoint of improving the controllability of the solid electrolyte filling amount.

[0092] The aforementioned porous substrate is preferably made of an insulating material. This improves the insulation of the solid electrolyte layer. Examples of insulating materials include: nylon, polyester, polyethylene, polypropylene, polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, polyvinylidene fluoride, polyvinylidene chloride, polyvinyl chloride, polyurethane, vinylon, polybenzimidazole, polyimide, polyphenylene sulfide, polyetheretherketone, cellulose, acrylic resin, and other resin materials; natural fibers such as hemp, wood pulp, and cotton linter; and glass.

[0093] (Insulation layer)

[0094] The insulating material forming the insulating layer 20 is not particularly limited, and examples include insulating oxides such as alumina, resins such as polyvinylidene fluoride (PVDF), and rubbers such as styrene-butadiene rubber (SBR).

[0095] Needle-shaped alumina 30 is a needle-like material composed of aluminum oxide. Aluminum has high electrical insulation and mechanical strength, and also has relatively high thermal conductivity.

[0096] The length of the needle-shaped alumina 30 is preferably 0.5 μm or more, more preferably 50 μm or more, and even more preferably 200 μm or more. When the length of the needle-shaped alumina 30 is at or above the aforementioned lower limit, the needle-shaped alumina 30 are arranged close to each other within the insulating layer 20, making it easy to form a thermal path based on the needle-shaped alumina 30. As a result, the heat generated by the electrode assembly 10 is effectively released to the outside of the solid-state battery cell 1 via the needle-shaped alumina 30 contained in the insulating layer 20.

[0097] The upper limit of the length of the needle-shaped alumina 30 can be less than 5000 μm, less than 1000 μm, or less than 500 μm. When the upper limit of the length of the needle-shaped alumina 30 is below the upper limit, the shape of the needle-shaped alumina 30 is ensured within the insulating layer 20, resulting in excellent heat dissipation from the electrode assembly 10 to the outside of the solid-state battery cell 1 via the needle-shaped alumina 30 contained in the insulating layer 20.

[0098] The diameter of the needle-shaped alumina 30 (the diameter in a cross-section perpendicular to the length direction) is preferably 0.1 μm or more and 10 μm or less, more preferably 0.5 μm or more and 5 μm or less, and even more preferably 0.5 μm or more and 1 μm or less. When the diameter of the needle-shaped alumina 30 is above the lower limit, it exhibits excellent dispersibility and easily forms a uniform thermal pathway within the layer. When the diameter of the needle-shaped alumina 30 is below the upper limit, it is easier to achieve a filling structure with fewer voids, which has a positive impact on heat exchange efficiency.

[0099] The aspect ratio of the needle-shaped alumina 30, i.e., the ratio of the length of the needle-shaped alumina 30 to its diameter (length of needle-shaped alumina 30 / diameter of needle-shaped alumina 30), is preferably 10 or more, more preferably 40 or more, and even more preferably 100 or more. When the aspect ratio of the needle-shaped alumina 30 is at or above the aforementioned lower limit, the needle-shaped alumina 30 are arranged close to each other within the insulating layer 20, making it easy to form a thermal path based on the needle-shaped alumina 30. As a result, the heat generated by the electrode assembly 10 is effectively released to the outside of the solid-state battery cell 1 via the needle-shaped alumina 30 contained in the insulating layer 20.

[0100] The aspect ratio of the needle-shaped alumina 30 can be below 1000, below 500, or below 200. When the aspect ratio of the needle-shaped alumina 30 is below the upper limit, the shape of the needle-shaped alumina 30 is ensured within the insulating layer 20, resulting in excellent heat dissipation from the electrode assembly 10 to the outside of the solid-state battery cell 1 via the needle-shaped alumina 30 contained in the insulating layer 20.

[0101] The content of needle-shaped alumina 30 relative to the total mass (100% by mass) of the insulating layer 20 is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 20% by mass or more. When the content of needle-shaped alumina 30 is at or above the aforementioned lower limit, the needle-shaped alumina 30 are arranged closely together within the insulating layer 20, making it easy to form a thermal pathway based on the needle-shaped alumina 30. As a result, the heat generated by the electrode assembly 10 is effectively released to the outside of the solid-state battery cell 1 via the needle-shaped alumina 30 contained in the insulating layer 20.

[0102] The upper limit of the content of needle-shaped alumina 30 relative to the total mass (100% by mass) of the insulating layer 20 can be 99% by mass or less, 40% by mass or less, or 20% by mass or less. When the content of needle-shaped alumina 30 is below the upper limit, the mechanical strength of the insulating layer 20 is sufficiently ensured, and the insulation layer 20 can be prevented from being damaged by external forces.

[0103] The particle size of the spherical alumina is preferably 10 nm or more and 5000 nm or less, more preferably 100 nm or more and 3000 nm or less, and even more preferably 300 nm or more and 1000 nm or less. When the particle size of the spherical alumina is above the lower limit, the dispersibility of the spherical alumina is excellent, and it can stably form thermal pathways. When the particle size of the spherical alumina is below the upper limit, the interface formation between it and adjacent layers becomes more uniform, and uniform heat conduction can be achieved.

[0104] The content of spherical alumina relative to the total mass (100% by mass) of the insulating layer 20 is preferably 10% by mass or more and 99% by mass or less, more preferably 50% by mass or more and 97% by mass or less, and even more preferably 85% by mass or more and 95% by mass or less. When the content of spherical alumina is at or above the lower limit, the distance between the spherical alumina and the needle-like alumina becomes closer, and the spherical alumina is more susceptible to the influence of the thermal pathways that form the needle-like alumina.

[0105] In the solid-state battery cell 1 according to this embodiment, the needle-shaped alumina 30 are arranged close to each other within the insulating layer 20, which easily forms a thermal path based on the needle-shaped alumina 30. Therefore, the heat generated in the electrode assembly 10 during charging and discharging can be released to the outside of the solid-state battery cell 1 via the needle-shaped alumina 30. The needle-shaped alumina 30 can conduct heat along its length direction, so the effect of releasing the heat generated in the electrode assembly 10 during charging and discharging to the outside of the solid-state battery cell 1 is superior to that of spherical alumina.

[0106] [Manufacturing method of solid-state battery cell]

[0107] Figure 2 This is a cross-sectional view of the slit die used in the manufacturing method of a solid-state battery cell according to an embodiment of the present invention.

[0108] In the manufacturing method of the solid-state battery cell of this embodiment, the solid-state battery cell includes: an electrode assembly comprising a positive electrode, a separator, and a negative electrode; and an insulating layer disposed around the outer periphery of the electrode assembly. The manufacturing method of the solid-state battery cell includes an insulating layer forming step, in which the insulating layer is formed by covering the outer periphery of the electrode assembly with an insulating composition comprising needle-shaped alumina using a die-coating method.

[0109] The method for manufacturing a solid-state battery cell in this embodiment is, for example, the method for manufacturing the solid-state battery cell 1 of the above embodiment.

[0110] The method for manufacturing a solid-state battery cell according to this embodiment may also include a modulation step for modulating the above-mentioned insulating composition. The modulation step includes: a first step of mixing the insulating material with spherical alumina to obtain a first compound; and a second step of mixing the first compound with needle-shaped alumina to obtain a second compound.

[0111] As an insulating material, it is not particularly limited, and for example, insulating oxides such as alumina, resins such as polyvinylidene fluoride (PVDF), and rubbers such as styrene-butadiene rubber (SBR) can be used.

[0112] The particle size of the spherical alumina is preferably 10 nm or more and 5000 nm or less, more preferably 100 nm or more and 3000 nm or less, and even more preferably 300 nm or more and 1000 nm or less. When the particle size of the spherical alumina is above or below the lower limit, the dispersibility of the spherical alumina is excellent, and thermal pathways can be stably formed. When the particle size of the spherical alumina is below the upper limit, the interface formation between it and adjacent layers becomes more uniform, and uniform heat conduction can be achieved.

[0113] The content of spherical alumina relative to the total mass (100% by mass) of the first compound is preferably 10% by mass or more and 99% by mass or less, more preferably 50% by mass or more and 97% by mass or less, and even more preferably 85% by mass or more and 95% by mass or less. When the content of spherical alumina is at or above the lower limit, the distance between the spherical alumina and the needle-like alumina becomes closer, and the spherical alumina is more susceptible to the influence of the thermal pathway that forms the needle-like alumina.

[0114] The method of mixing insulating materials with spherical alumina is not particularly limited, and examples include self-rotating stirring, continuous biaxial mixing, planetary motion mixing, and single-axis stirring.

[0115] The length of the needle-shaped alumina is preferably 0.5 μm or more, more preferably 50 μm or more, and even more preferably 200 μm or more. When the length of the needle-shaped alumina is at or above the lower limit value, the needle-shaped alumina are arranged close to each other in the insulating composition, which facilitates the formation of thermal pathways based on the needle-shaped alumina.

[0116] The upper limit of the length of the needle-shaped alumina can be less than 5000 μm, less than 1000 μm, or less than 500 μm. When the upper limit of the length of the needle-shaped alumina is less than or equal to the stated upper limit, the shape of the needle-shaped alumina can be maintained while modulating the insulating composition.

[0117] The diameter of the needle-shaped alumina (the diameter in a cross-section perpendicular to the length direction) is preferably 0.1 μm or more and 10 μm or less, more preferably 0.5 μm or more and 5 μm or less, and even more preferably 0.5 μm or more and 1 μm or less. When the diameter of the needle-shaped alumina is above or below the lower limit, it exhibits excellent dispersibility and easily forms uniform thermal pathways within the layer. When the diameter of the needle-shaped alumina is below the upper limit, it is easier to achieve a filling structure with fewer voids, which has a positive impact on heat exchange efficiency.

[0118] The aspect ratio of the needle-shaped alumina, i.e., the ratio of the length of the needle-shaped alumina to its diameter (length of needle-shaped alumina / diameter of needle-shaped alumina), is preferably 10 or more, more preferably 40 or more, and even more preferably 100 or more. When the aspect ratio of the needle-shaped alumina is at or above the aforementioned lower limit value, the needle-shaped alumina are arranged close to each other within the insulating composition, making it easy to form a thermal path based on the needle-shaped alumina.

[0119] The upper limit of the aspect ratio of needle-shaped alumina can be 1000 or less, 500 or less, or 200 or less. When the upper limit of the aspect ratio of needle-shaped alumina is below the upper limit, it is possible to modulate an insulating composition while maintaining the shape of the needle-shaped alumina.

[0120] The content of needle-shaped alumina relative to the total mass (100% by mass) of the second compound is preferably 1% by mass or more, more preferably 5% by mass or more, and even more preferably 20% by mass or more. When the content of needle-shaped alumina is at or above the aforementioned lower limit, the needle-shaped alumina are arranged close to each other in the insulating composition, which facilitates the formation of thermal pathways based on the needle-shaped alumina.

[0121] In the insulating layer formation process, an insulating layer is formed by covering the outer periphery of the electrode assembly with an insulating composition containing needle-shaped alumina using a die coating method.

[0122] In the insulation layer formation process, Figure 2 Within the flow path 101 of the slit die 100 shown, the flow velocity of the insulating component is controlled to be from the length direction of the flow path 101 (the flow direction of the insulating component) Figure 2 The flow rate of the insulating component gradually decreases from the center of the flow path 101 towards the inner wall surface 101a, as indicated by arrow A. To control the flow rate of the insulating component to gradually decrease from the center of the flow path 101 along its length towards the inner wall surface 101a, a shear stress difference is utilized within the flow path 101 of the slit die 100. Consequently, within the flow path 101, the needle-shaped alumina 30 flows along its length direction... Figure 2As shown by arrow A, the insulating component containing needle-shaped alumina ejected from the nozzle 102 of the slit die 100 is supplied to the periphery of the electrode assembly in a state oriented in one direction.

[0123] According to the solid-state battery cell manufacturing method of this embodiment, the needle-shaped alumina are arranged close to each other, which makes it easy to form a thermal path based on the needle-shaped alumina. Therefore, an insulating layer can be formed to release the heat generated in the electrode assembly during charging and discharging to the outside of the solid-state battery cell via the needle-shaped alumina.

[0124] The embodiments of the present invention have been described in detail above, but the present invention is not limited to the above embodiments. Various modifications and alterations can be made within the scope of the spirit of the present invention as described in the technical solution.

Claims

1. A solid-state battery cell comprising: an electrode assembly including a positive electrode, a separator, and a negative electrode; and an insulating layer disposed around the outer periphery of the electrode assembly, wherein, The insulating layer comprises needle-shaped aluminum oxide.

2. The solid-state battery cell according to claim 1, wherein, The needle-shaped alumina is oriented from the interface between the electrode assembly and the insulating layer toward the outer surface of the insulating layer.

3. The solid-state battery cell according to claim 1, wherein, The content of needle-shaped alumina relative to the total mass of the insulating layer is 20% by mass or more.

4. The solid-state battery cell according to claim 1, wherein, The needle-shaped alumina has a length of 50 μm or more and an aspect ratio of 100 or more.

5. The solid-state battery cell according to claim 1, wherein, The insulating layer comprises spherical aluminum oxide.

6. A method for manufacturing a solid-state battery cell, the solid-state battery cell comprising: an electrode assembly including a positive electrode, a separator, and a negative electrode; and an insulating layer disposed around the outer periphery of the electrode assembly, wherein, The method for manufacturing the solid-state battery cell includes an insulating layer forming step, in which an insulating layer is formed by using a die-coating method to cover the outer periphery of the electrode assembly with an insulating composition containing needle-shaped alumina.

7. The method for manufacturing a solid-state battery cell according to claim 6, wherein, In the flow path of the slit die used in the molding process, the flow rate of the insulating component is controlled to slow down from the center of the flow path along its length toward the inner wall surface of the flow path.

8. The method for manufacturing a solid-state battery cell according to claim 7, wherein, The width of the nozzle of the slit head is greater than 100μm and less than 1000μm.

9. The method for manufacturing a solid-state battery cell according to claim 6, wherein, The manufacturing method of the solid-state battery cell includes a modulation step for modulating the insulating components. The modulation process includes: a first step of mixing insulating material with spherical alumina to obtain a first compound; and a second step of mixing the first compound with needle-shaped alumina to obtain a second compound.

10. The method for manufacturing a solid-state battery cell according to claim 9, wherein, The needle-shaped alumina has a length of 50 μm or more and an aspect ratio of 100 or more.

11. The method for manufacturing a solid-state battery cell according to claim 9, wherein, The spherical alumina has a particle size of 10 nm or more and 5000 nm or less.

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