Manufacturing method for electrodes for all-solid-state batteries

Abstract

To provide a simple manufacturing method for electrode bodies for all-solid-state batteries that reduces short circuits when a load such as pressure is applied to a part of the positive electrode current collector that may come into contact with the edge or burr of the solid electrolyte layer or the negative electrode active material layer. [Solution] A method for manufacturing an electrode body for an all-solid-state battery, comprising an insulating layer forming step in which an insulating coating agent with a predetermined viscosity or less is poured into a stepped portion formed between the surface of the positive electrode current collector on the side where the positive electrode active material layer is provided and the surface along the thickness direction of the positive electrode active material layer, and then subjected to a reduced pressure treatment to form the insulating layer consisting of an insulating coating.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing an electrode body for an all-solid-state battery.

Background Art

[0002] All-solid-state batteries using solid electrolytes have been developed. Currently developed all-solid-state batteries have a laminated structure. Specifically, they have a laminated structure including a positive electrode current collector, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a plurality of negative electrode current collectors. Also, the positive electrode current collectors are each grouped together and joined to a positive electrode current collecting tab, and the negative electrode current collectors are also each grouped together and joined to a negative electrode current collecting tab. Further, from the perspective of electrode efficiency (eliminating wasted space) within the battery, a part of the current collecting foil is bent so as to be close to the end of the solid electrolyte layer, the positive electrode active material layer, or the negative electrode active material layer.

[0003] For example, Patent Document 1 discloses "an all-solid-state secondary battery comprising a positive electrode layer, a negative electrode layer, a solid electrolyte layer disposed between them, and an insulating layer for suppressing short-circuiting due to contact between the positive electrode layer and the negative electrode layer, wherein the solid electrolyte layer is laminated on both surfaces of the positive electrode layer, the negative electrode layer is laminated on the surfaces of the respective solid electrolyte layers opposite to the positive electrode layer, the insulating layer is disposed so as to cover the side end face of the positive electrode layer, and the position of the outer edge of the positive electrode layer covered by the insulating layer is optically distinguishable through the insulating layer." For example, Patent Document 2 discloses "an all-solid-state laminated battery comprising a positive electrode current collector, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector, wherein one end of the positive electrode active material layer is located inside one end of the negative electrode active material layer and the solid electrolyte layer, and an insulating film is formed on a portion of the surface of the positive electrode current collector on the solid electrolyte layer side, which portion includes a portion facing one end of the negative electrode active material layer and the solid electrolyte layer in the lamination direction." <00000​​​​

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-151405 [Patent Document 2] Japanese Patent Publication No. 2020-123536 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The positive electrode current collector is generally bent and bundled so as to be close to the edge of the solid electrolyte layer or the negative electrode active material layer. Therefore, for example, when sealing under reduced pressure in a laminate cell, the positive electrode current collector may come into contact with or be pressed against the edge of the solid electrolyte layer or the negative electrode active material layer, causing a short circuit. Also, when manufacturing the laminate, the solid electrolyte layer or the active material layer may be cut, resulting in burrs forming on the edge of the solid electrolyte layer or the negative electrode active material layer. Therefore, during sealing under reduced pressure, the positive electrode current collector may come into contact with or be pressed against these burrs, causing a short circuit. For this reason, an insulating layer made of an insulating coating is provided on the positive electrode current collector in areas that may come into contact with the edge or burrs of the solid electrolyte layer or the negative electrode active material layer (for example, as shown in Figure 1 later, the stepped portion formed by the surface of the positive electrode current collector on the side where the positive electrode active material layer is provided and the surface along the thickness direction of the positive electrode active material layer). However, the aforementioned portion resembles a narrow groove when viewed from the surface on the side of the positive electrode current collector where the positive electrode active material layer is provided, making it difficult to stably form an insulating layer. Therefore, the object of this disclosure is to provide a simple manufacturing method for an electrode body for an all-solid-state battery that reduces short circuits when a load such as pressure is applied to a portion of the positive electrode current collector that may come into contact with the edge or burr of the solid electrolyte layer or the negative electrode active material layer. [Means for solving the problem]

[0006] The means to solve the above problems include the following: <1> A method for manufacturing an electrode body for an all-solid-state battery, comprising a positive electrode current collector, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector in this order, further comprising an insulating layer provided so as to be in direct contact with a part of the surface of the positive electrode current collector on the side where the positive electrode active material layer is provided and a part of the surface of the positive electrode active material layer along the thickness direction, wherein one end of the positive electrode active material layer is located inside the one end of the solid electrolyte layer, the method for manufacturing an electrode body for an all-solid-state battery includes an insulating layer formation step in which an insulating coating agent with a predetermined viscosity or less is poured into a stepped portion formed between the surface of the positive electrode current collector on the side where the positive electrode active material layer is provided and the surface of the positive electrode active material layer along the thickness direction, and then subjected to a reduced pressure treatment to form the insulating layer consisting of an insulating coating. [Effects of the Invention]

[0007] The problem that one embodiment of this disclosure aims to solve is to provide a simple manufacturing method for an electrode body for an all-solid-state battery that reduces short circuits when a load such as pressure is applied to a part of the positive electrode current collector that may come into contact with the edge or burr of the solid electrolyte layer or the negative electrode active material layer. [Brief explanation of the drawing]

[0008] [Figure 1] This is a cross-sectional view focusing on the end of the positive electrode current collector tab in an all-solid-state battery manufactured by a conventional manufacturing method. [Figure 2] This is a cross-sectional view focusing on the end of the positive electrode current collector tab in an all-solid-state battery manufactured by the manufacturing method of the present disclosure. [Modes for carrying out the invention]

[0009] The following describes an example of an embodiment of this disclosure. These descriptions are illustrative and do not limit the scope of the invention.

[0010] <Method for manufacturing electrodes for solid-state batteries> A method for manufacturing an electrode body for a solid-state battery according to the present disclosure comprises a positive electrode current collector, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector in that order, further comprising an insulating layer provided so as to be in direct contact with a part of the surface of the positive electrode current collector on the side where the positive electrode active material layer is provided and a part of the surface of the positive electrode active material layer along the thickness direction, and one end of the positive electrode active material layer being located inside the one end of the solid electrolyte layer, the manufacturing method for an electrode body for a solid-state battery includes an insulating layer forming step in which an insulating coating agent with a predetermined viscosity or less is poured into a stepped portion formed between the surface of the positive electrode current collector on the side where the positive electrode active material layer is provided and the surface of the positive electrode active material layer along the thickness direction, and then subjected to a reduced pressure treatment to form the insulating layer consisting of an insulating coating.

[0011] Figure 1 is a cross-sectional view focusing on the positive electrode current collector tab end of an all-solid-state battery 100 manufactured by a conventional manufacturing method. Figure 2 is a cross-sectional view focusing on the positive electrode current collector tab end of an all-solid-state battery 100 including an electrode body manufactured by the manufacturing method of the present disclosure. As shown in Figures 1 and 2, the all-solid-state battery 100 is a laminate in which a positive electrode current collector 1, a positive electrode active material layer 2, a solid electrolyte layer 3, a negative electrode active material layer 4, and a negative electrode current collector 5 are stacked in this order. The all-solid-state battery 100 shown in Figures 1 and 2 is a laminated battery comprising a positive electrode 10 having a positive electrode active material layer 2 on both sides of the positive electrode current collector 1, a negative electrode 20 having a negative electrode active material layer 4 on both sides of the negative electrode current collector 5, and a solid electrolyte layer 3 disposed between the positive electrode 10 and the negative electrode 20. However, the all-solid-state battery obtained by the manufacturing method of this disclosure does not have to be a laminated battery. In other words, it is sufficient to have at least one positive electrode 10, a negative electrode 20, and a solid electrolyte layer 3. In Figures 1 and 2, a positive electrode current collector 1 is positioned at the positive electrode active material side of the all-solid-state battery 100, and a negative electrode current collector 5 is positioned at the negative electrode active material layer 4 side. As shown in Figure 1, the all-solid-state battery 100 obtained by a conventional manufacturing method is equipped with an insulating layer that does not directly contact the end of the positive electrode active material layer in the thickness direction. In other words, a part of the surface of the positive electrode current collector 1 on the side where the positive electrode active material layer 2 is provided and a part of the surface of the positive electrode active material layer along the thickness direction are not in direct contact. Therefore, for example, when a load such as pressure is applied to a part of the positive electrode current collector that may come into contact with the end or burr of the solid electrolyte layer or negative electrode active material layer, such as when sealing under reduced pressure in a laminate cell, the insulating layer 1a may not function and a short circuit may occur. In contrast, as shown in Figure 2, the all-solid-state battery 100 manufactured by the manufacturing method of the present disclosure further comprises an insulating layer 1a that is in direct contact with a part of the surface of the positive electrode current collector 1 on the side where the positive electrode active material layer 2 is provided, and a part of the surface of the positive electrode active material layer 2 along the thickness direction, and one end of the positive electrode active material layer is located inward from one end of the solid electrolyte layer. The insulating layer 1a is formed by pouring an insulating coating agent with a predetermined viscosity or lower into a stepped portion formed between the surface of the positive electrode current collector on the side where the positive electrode active material layer is provided and the surface of the positive electrode active material layer along the thickness direction, and then subjecting it to a reduced pressure treatment to form the insulating layer consisting of an insulating coating. Therefore, in the all-solid-state battery 100 obtained by the manufacturing method of this disclosure, short circuits are reduced when a load such as pressure is applied to a part of the positive electrode current collector that may come into contact with the edge or burr of the solid electrolyte layer or the negative electrode active material layer.

[0012] Although not shown in the illustrations, in the all-solid-state battery 100 obtained by the manufacturing method of this disclosure, the positive electrode current collector 1 is bundled together on one side of the end of the all-solid-state battery 100 (the left side of the page in Figure 1) and joined to the positive electrode current collector tab. Furthermore, of the end of the positive electrode current collector 1 that is bundled to the positive electrode current collector tab, some or all of it extends outward beyond the ends of the solid electrolyte layer 3 and the negative electrode active material layer 4. The negative electrode current collector 5 is similarly bundled and joined to the negative electrode current collector tab. The position of the negative electrode current collector tab is not particularly limited and may be on one side of the end of the all-solid-state battery 100 or on the other side.

[0013] In this disclosure, the term "electrode body" means a structure including a laminate comprising a positive electrode, a negative electrode, and a solid electrolyte layer disposed between the positive and negative electrodes. Known configurations and materials used in solid-state batteries can be applied as the positive electrode current collector, positive electrode active material layer, solid electrolyte layer, negative electrode active material layer, and negative electrode current collector.

[0014] The material of the positive electrode current collector can be, for example, metal or carbon. Examples of positive electrode current collector materials include stainless steel, aluminum, nickel, iron, titanium, and carbon, with aluminum alloy foil or aluminum foil being preferred. Aluminum alloy foil and aluminum foil may be manufactured using powder. Examples of positive electrode current collector shapes include foil-like and mesh-like, with foil-like being preferred. The positive electrode current collector and negative electrode current collector may each consist of a single sheet, or two or more sheets stacked on top of each other.

[0015] The positive electrode active material layer contains at least positive electrode active material. The positive electrode active material layer may optionally contain conductive additives, solid electrolytes, binders, and other components. The positive electrode active material preferably contains a lithium composite oxide. The lithium composite oxide may contain at least one element selected from the group consisting of F, Cl, N, S, Br, and I. The lithium composite oxide may also have a crystal structure belonging to at least one space group selected from the space groups R-3m, Immmm, and P63-mmc (also called P63mc or P6 / mmc). Furthermore, the lithium composite oxide may have an O2-type structure in which the main arrangement of the transition metal, oxygen, and lithium is located. Examples of the conductive aid include carbon materials, metal materials, and conductive polymer materials. Examples of the carbon materials include carbon black (e.g., acetylene black, furnace black, ketjen black, etc.), fibrous carbon (e.g., vapor-grown carbon fiber, carbon nanotube, carbon nanofiber, etc.), graphite, carbon fluoride, etc. Examples of the metal materials include metal powder (e.g., aluminum powder, etc.), conductive whiskers (e.g., zinc oxide, potassium titanate, etc.), conductive metal oxides (e.g., titanium oxide, etc.), etc. Examples of the conductive polymer materials include polyaniline, polypyrrole, polythiophene, etc. The conductive aid may be used alone as only one type, or may be used by mixing two or more types. As the solid electrolyte, it is preferable to contain at least one solid electrolyte species selected from the group of solid electrolytes consisting of sulfide solid electrolytes, oxide solid electrolytes, and halide solid electrolytes. Specific examples of the sulfide solid electrolyte, oxide solid electrolyte, and halide solid electrolyte are the same as those described later and are applicable. Examples of the binder include vinyl halide resins, rubbers, polyolefin resins, etc. Examples of the other components include oxide solid electrolytes, halide solid electrolytes, thickeners, surfactants, dispersants, wetting agents, defoamers, solvents, etc.

[0016] The solid electrolyte layer contains at least a solid electrolyte. The solid electrolyte layer preferably contains one selected from the group consisting of sulfide solid electrolytes, oxide solid electrolytes, and halide solid electrolytes. As the sulfide solid electrolyte, it preferably contains sulfur (S) as the main component of the anion element, and further preferably contains, for example, Li element and A element. The A element is at least one selected from the group consisting of P, As, Sb, Si, Ge, Sn, B, Al, Ga, and In. As the oxide solid electrolyte, as the main component of the anion element, it contains oxygen (O), and for example, it may contain Li and a Q element (Q represents at least one of Nb, B, Al, Si, P, Ti, Zr, Mo, W, and S). As the halide solid electrolyte, a solid electrolyte containing Li, M, and X (M represents at least one of Ti, Al, and Y, and X represents F, Cl, or Br) is preferable. The solid electrolyte layer may or may not contain a binder. As the binder that can be contained in the solid electrolyte layer, the same ones as those of the aforementioned binder are applicable.

[0017] The negative electrode active material layer contains at least a negative electrode active material. The negative electrode active material layer may contain at least one of a solid electrolyte for the negative electrode, a conductive assistant, and a binder as required. Examples of the negative electrode active material include Li-based active materials such as metallic lithium, carbon-based active materials such as graphite, oxide-based active materials such as lithium titanate, and Si-based active materials such as elemental Si. The conductive assistant, the solid electrolyte for the negative electrode, and the binder used in the negative electrode active material layer are the same as those exemplified as the conductive assistant contained in the positive electrode active material layer, the solid electrolyte contained in the solid electrolyte layer, and the binder.

[0018] Examples of the negative electrode current collector include the same ones as those exemplified for the positive electrode current collector described above.

[0019] In the insulating layer forming step, after pouring an insulating film agent having a viscosity below a predetermined viscosity onto the step portion formed by the surface of the positive electrode current collector on the side where the positive electrode active material layer is provided and the surface along the thickness direction of the positive electrode active material layer, a reduced pressure treatment is performed to form the insulating layer made of an insulating film. In the electrode body for an all-solid-state battery manufactured through the insulating layer forming step, a short circuit when a load such as pressure is applied to a part of the positive electrode current collector that may come into contact with the end portion or burr of the solid electrolyte layer or the negative electrode active material layer is reduced. The viscosity below the predetermined viscosity is preferably, for example, a viscosity that can be poured into the gap between the electrode laminates from the viewpoint of easier manufacturing. The pressure during the depressurization process is not particularly limited and may be designed as appropriate, as long as it is within the range in which the insulating coating agent poured into the gaps between the electrode stacks dries and an insulating coating is formed.

[0020] The manufacturing method relating to this disclosure may further include other steps besides the insulating layer formation step. Examples of other steps include the following: (1) Preparation step of preparing an electrode body comprising a positive electrode current collector, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector in that order; (2) A machining process in which the electrode body is cut or otherwise processed. [Explanation of Symbols]

[0021] 1a Insulating layer, 1 Positive electrode current collector, 2 Positive electrode active material layer, 3 Solid electrolyte layer, 4 Negative electrode active material layer, 5 Negative electrode current collector, 10 Positive electrode, 20 Negative electrode, 100 All-solid-state battery

Claims

[Claim 1] In the manufacture of an electrode body for an all-solid-state battery, comprising a positive electrode current collector, a positive electrode active material layer, a solid electrolyte layer, a negative electrode active material layer, and a negative electrode current collector in this order, further comprising an insulating layer provided so as to be in direct contact with a part of the surface of the positive electrode current collector on the side where the positive electrode active material layer is provided and a part of the surface of the positive electrode active material layer along the thickness direction, and wherein one end of the positive electrode active material layer is located inward from one end of the solid electrolyte layer, A method for manufacturing an electrode body for an all-solid-state battery, comprising an insulating layer forming step, in which an insulating coating agent with a predetermined viscosity or lower is poured into a stepped portion formed between the surface of the positive electrode current collector on the side where the positive electrode active material layer is provided and the surface of the positive electrode active material layer along the thickness direction, and then subjected to a reduced pressure treatment to form the insulating layer consisting of an insulating coating.

Images