WO2023080216A1

WO2023080216A1 - Insulating film, all-solid-state battery, and method for manufacturing all-solid-state battery

Info

Publication number: WO2023080216A1
Application number: PCT/JP2022/041247
Authority: WO
Inventors: 秀紀浅井
Original assignee: 大日本印刷株式会社
Priority date: 2021-11-04
Filing date: 2022-11-04
Publication date: 2023-05-11

Abstract

Provided is an insulating film used for an all-solid-state battery, wherein: the all-solid-state battery includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer; the insulating film is disposed along the outer contour of at least one among the positive electrode layer and the negative electrode layer so as to be joined to at least one among the positive electrode layer and the negative electrode layer, and includes a first layer and a second layer laminated on the first layer; and the material constituting the first layer and the material constituting the second layer are different in terms of either melting point or melt mass-flow rate.

Description

Insulating film, all-solid-state battery, method for manufacturing all-solid-state battery

The present invention relates to an insulating film, an all-solid-state battery including the same, and a method for manufacturing the same.

Patent Document 1 discloses an example of an all-solid-state battery. This all-solid-state battery includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer. The solid electrolyte layer includes a central portion containing a solid electrolyte and an outer peripheral portion formed along the outer circumference of the central portion. The outer peripheral portion is made of an insulating material. In manufacturing this all-solid-state battery, a laminate is manufactured in which a positive electrode layer, a negative electrode layer, and a solid electrolyte layer are laminated such that the solid electrolyte layer is disposed between the positive electrode layer and the negative electrode layer. By press-molding this laminate, the positive electrode layer, the solid electrolyte layer, and the negative electrode layer are densified, in other words, the porosity is reduced, and an all-solid battery is manufactured.

JP 2020-173953 A

In the all-solid-state battery, for example, if the relative positions of the positive electrode layer and the negative electrode layer are misaligned, the outer peripheral edge of the positive electrode layer and the outer peripheral edge of the negative electrode layer are damaged during press molding, causing a short circuit. There is a risk. Such short-circuit problems also arise, for example, when the sizes of the positive electrode layer and the negative electrode layer are different in plan view. Further, even if the positive electrode layer and the negative electrode layer have the same size in plan view, for example, at least one of the positive electrode layer and the negative electrode layer may have burrs or the like during manufacturing, and the positive electrode layer may extend beyond the solid electrolyte layer. The same occurs when the edge and the edge of the negative electrode layer are in contact.

An object of the present invention is to provide an insulating film that contributes to preventing the occurrence of a short circuit during the manufacture of an all-solid-state battery, an all-solid-state battery including the same, and a method for manufacturing the same.

An insulating film according to a first aspect of the present invention is an insulating film used in an all-solid-state battery, and the all-solid-state battery includes a positive electrode layer, a negative electrode layer, and between the positive electrode layer and the negative electrode layer and the insulating film is arranged along the outline of at least one of the positive electrode layer and the negative electrode layer so as to be bonded to at least one of the positive electrode layer and the negative electrode layer. , a first layer, and a second layer laminated on the first layer, wherein the material constituting the first layer and the material constituting the second layer have at least one of a melting point and a melt mass flow rate is different.

An insulating film according to a second aspect of the present invention is the insulating film according to the first aspect, wherein the material forming the first layer has a higher melting point than the material forming the second layer, and the The melting point of the material forming the second layer is 170° C. or lower.

An insulating film according to a third aspect of the present invention is the insulating film according to the first aspect or the second aspect, wherein the material forming the first layer has a melting point lower than that of the material forming the second layer. is high, and the melting point of the material forming the first layer is 250° C. or higher.

The insulating film according to the fourth aspect of the present invention is the insulating film according to any one of the first to third aspects, wherein the material constituting the first layer constitutes the second layer The difference between the melting point of the material forming the first layer and the melting point of the material forming the second layer is 50° C. or more.

An insulating film according to a fifth aspect of the present invention is the insulating film according to any one of the first to fourth aspects, wherein the material constituting the first layer constitutes the second layer. The melt mass flow rate at 190°C of the material constituting the second layer is 0.8 g/10 min or more at 190°C.

The insulating film according to the sixth aspect of the present invention is the insulating film according to any one of the first to fifth aspects, wherein the material constituting the first layer constitutes the second layer The melt mass flow rate at 190°C of the material constituting the first layer is 0.1 g/10 min or less at 190°C.

An insulating film according to a seventh aspect of the present invention is the insulating film according to any one of the first to sixth aspects, wherein the material constituting the first layer constitutes the second layer. The difference between the melt mass flow rate of the material forming the second layer and the melt mass flow rate of the material forming the first layer is, at 190° C., 0.5°C. 8 g/10 min or more.

An insulating film according to an eighth aspect of the present invention is an insulating film used in an all-solid-state battery, wherein the all-solid-state battery includes a positive electrode layer, a negative electrode layer, and between the positive electrode layer and the negative electrode layer and the insulating film is arranged along the outline of at least one of the positive electrode layer and the negative electrode layer so as to be bonded to at least one of the positive electrode layer and the negative electrode layer. , a first layer, and a second layer laminated on the first layer, the material constituting the first layer includes polyester or engineering plastic, and the material constituting the second layer is polyolefin include.

The all-solid-state battery according to the ninth aspect of the present invention comprises the insulating film according to any one of the first to eighth aspects.

A method for manufacturing an all-solid-state battery according to a tenth aspect of the present invention is a method for manufacturing an all-solid-state battery comprising an insulating film according to any one of the first to eighth aspects, wherein the all-solid-state battery comprises , a positive electrode layer, a negative electrode layer, a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, and the positive electrode layer and the negative electrode layer so as to be bonded to at least one of the positive electrode layer and the negative electrode layer. and the insulating film arranged along the outline of at least one of the layers, wherein the positive electrode layer and the negative electrode layer are arranged such that the solid electrolyte layer is arranged between the positive electrode layer and the negative electrode layer. , and a lamination step of manufacturing a laminate by laminating the solid electrolyte layers, and a bonding step of hot-pressing the laminate to join the laminate, which is performed after the lamination step. and a sealing step of sealing the laminate with a packaging material, which is performed before or after the bonding step, and in the laminating step, the insulating film is formed around at least one of the positive electrode layer and the negative electrode layer. A film is placed.

A method for manufacturing an all-solid-state battery according to an eleventh aspect of the present invention includes a positive electrode layer, a negative electrode layer, a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, and the positive electrode layer and the negative electrode layer. and an insulating film disposed along an outer shell of at least one of the positive electrode layer and the negative electrode layer so as to be bonded to at least one of the positive electrode layer and the negative electrode layer. a stacking step of manufacturing a stack by stacking the positive electrode layer, the negative electrode layer, and the solid electrolyte layer such that the solid electrolyte layer is disposed between the stacking step and the stacking step; and a bonding step of bonding the laminate by hot-pressing the laminate, and a sealing step of sealing the laminate with a packaging material performed before or after the bonding step. , in the laminating step, the insulating film is arranged around at least one of the positive electrode layer and the negative electrode layer, and the insulating film comprises a first layer and a second layer laminated on the first layer; wherein at least one of a melting point and a melt mass flow rate is different between the material forming the first layer and the material forming the second layer.

An all-solid-state battery according to a twelfth aspect of the present invention includes a positive electrode layer, a negative electrode layer, a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer, and at least one of the positive electrode layer and the negative electrode layer an insulating film disposed along at least one of the positive electrode layer and the negative electrode layer so as to be in contact with the positive electrode layer and the negative electrode layer.

An all-solid-state battery according to a thirteenth aspect of the present invention is the all-solid-state battery according to the twelfth aspect, wherein the insulating film includes a first layer and a second layer laminated on the first layer. , the second layer is arranged along the outline of at least one of the positive electrode layer and the negative electrode layer, and the first layer is arranged at least one between the solid electrolyte layer and the negative electrode layer or the positive electrode layer. placed in the department.

An all-solid-state battery according to a fourteenth aspect of the present invention is the all-solid-state battery according to the twelfth aspect or the thirteenth aspect, wherein the insulating film partially overlaps the solid electrolyte layer in plan view. placed in

The insulating film, all-solid-state battery, and method for manufacturing an all-solid-state battery according to the present invention can contribute to making short circuits less likely to occur during manufacture of all-solid-state batteries.

1 is a plan view of an all-solid-state battery according to an embodiment; FIG. FIG. 2 is a cross-sectional view taken along line D2-D2 of FIG. 1; FIG. 3 is a plan view of the insulating film of FIG. 2; FIG. 3 is a cross-sectional view showing an example of the layer structure of the laminated film of FIG. 2; 2 is a flowchart showing an example of a method for manufacturing the all-solid-state battery of FIG. 1; FIG. 5 is a diagram of a state in which an insulating film is arranged on a negative electrode layer in the lamination step of the manufacturing method of the all-solid-state battery of FIG. 4 ; The figure of the state which laminated|stacked the positive electrode layer on the state of FIG. FIG. 7 is a diagram of a state in which an insulating film is arranged in the state of FIG. 6; FIG. 8 is a view showing a state in which a negative electrode layer is laminated on the state shown in FIG. 7; Sectional drawing which shows the layer structure of the insulating film of a modification. Sectional drawing of the lamination|stacking unit with which the all-solid-state battery of a modification is provided. Sectional drawing of the lamination|stacking unit with which the all-solid-state battery of another modification is provided. Sectional drawing which shows the layer structure of the insulating film of another modification. 4 is a table showing specifications and test results of all-solid-state batteries of Examples and Comparative Examples; FIG. 2 is a cross-sectional view of an all-solid-state battery of Comparative Example 2; FIG. 3 is a cross-sectional view of an all-solid-state battery of Comparative Example 3;

An all-solid-state battery according to one embodiment of the present invention will be described below with reference to the drawings. In this specification, the numerical range indicated by "-" means "more than" and "less than". For example, the notation of 2 to 15 mm means 2 mm or more and 15 mm or less.

<1. Overall configuration of all-solid-state battery>
FIG. 1 is a plan view of an all-solid-state battery 10 of this embodiment. FIG. 2 is a cross-sectional view along line D2-D2. Hereinafter, for convenience of explanation, unless otherwise specified, the vertical direction in FIG. 1 will be referred to as "front and rear", the horizontal direction will be referred to as "left and right", and the vertical direction in FIG. 2 will be referred to as "up and down". However, the orientation during use of the all-solid-state battery 10 is not limited to this. Also, in the drawings used in the following description, characteristic parts may be enlarged for convenience of description, and the dimensional ratios and the like of each component are not limited to those shown in the drawings.

The all-solid battery 10 is, for example, an all-solid lithium-ion secondary battery, an all-solid sodium-ion secondary battery, or an all-solid magnesium-ion secondary battery. In this embodiment, the all-solid battery 10 is an all-solid lithium ion secondary battery. The all-solid-state battery 10 is used, for example, in electric vehicles such as electric vehicles and hybrid vehicles that are connected in series and used at high voltage. All-solid-state battery 10 includes container 20 , laminate unit 30 , tab 80 , and tab film 90 .

The container 20 has an internal space S1 and a peripheral seal portion 23 . The laminate unit 30 is housed in the internal space S<b>1 of the housing 20 . One end of the tab 80 is joined to the laminate unit 30 , and the other end protrudes outward from the peripheral seal portion 23 of the container 20 . A portion between one end and the other end of the tab 80 is fused to the peripheral seal portion 23 via the tab film 90 .

The container 20 includes a container 20A. 20 A of containers are comprised including the

packaging materials

21 and 22. As shown in FIG. At the outer peripheral portion of the container 20A in plan view, the

packaging materials

21 and 22 are heat-sealed and fused together, thereby forming a peripheral edge seal portion 23 . The inner space S1 of the container 20A, which is isolated from the outer space, is formed by the peripheral seal portion 23. As shown in FIG. The peripheral edge seal portion 23 defines the peripheral edge of the internal space S1 of the container 20A. It should be noted that the mode of heat sealing referred to herein includes modes such as thermal fusion from a heat source and ultrasonic fusion. In any case, the peripheral seal portion 23 means a portion where the

packaging materials

21 and 22 are fused and integrated. Note that the packaging material 22 , the tab 80 , the pair of tab films 90 , and the packaging material 21 are integrated at the portion of the peripheral seal portion 23 sandwiching the tab 80 and the tab film 90 . The packaging material 22 , the pair of tab films 90 , and the packaging material 21 are integrated in the portion of the peripheral seal portion 23 that sandwiches only the pair of tab films 90 .

The

packaging materials

21 and 22 are composed of resin molded products or films, for example. The resin molded product referred to here can be manufactured by methods such as injection molding, pressure molding, vacuum molding, and blow molding, and in-mold molding may be performed to impart design and functionality. The type of resin can be polyolefin, polyester, nylon, ABS, and the like. The film referred to here is, for example, a resin film that can be produced by a method such as an inflation method or a T-die method, or a laminate of such a resin film on a metal foil. The film referred to here may or may not be stretched, and may be a single-layer film or a multilayer film. The multilayer film referred to here may be produced by a coating method, may be produced by adhering a plurality of films with an adhesive or the like, or may be produced by a multilayer extrusion method.

As described above, the

packaging materials

21 and 22 can be configured in various ways, but in this embodiment, they are composed of laminated films. A laminate film can be a laminate obtained by laminating a substrate layer, a barrier layer, and a heat-fusible resin layer. The base layer functions as a base material for the

packaging materials

21 and 22, typically forms the outer layer side of the container 20A, and is made of polyester such as polyethylene terephthalate or polybutylene terephthalate, polyamide such as nylon, or the like. The resin layer may be formed of a single layer or multiple layers of two or more layers. In addition to improving the strength of the

packaging materials

21 and 22, the barrier layer has a function of preventing at least moisture from entering the laminate unit 30, and is typically aluminum alloy foil, stainless steel foil, or titanium foil. It is a metal layer made of steel foil, steel plate foil, or the like. The heat-sealable resin layer is typically made of heat-sealable resin such as polyolefin such as polypropylene, polyester such as polyethylene terephthalate and polybutylene terephthalate, and forms the innermost layer of the container 20A. The shape of the container 20A is not particularly limited, and can be, for example, a bag shape (pouch shape). The bag-like shape referred to herein includes a three-side seal type, a four-side seal type, a pillow type, a gusset type, and the like. Note that the container 20A may be composed of the

packaging materials

21 and 22, but may also be, for example, a metal can.

The tab 80 is a metal terminal used for power input/output of the all-solid-state battery 10 . The tabs 80 are arranged separately at the left and right ends of the peripheral seal portion 23 of the container 20A, one constituting a positive terminal and the other constituting a negative terminal. One end in the left-right direction of each tab 80 is electrically connected to the positive electrode layer 40 or the negative electrode layer 50 (both see FIG. 2) of the laminate unit 30 in the internal space S1 of the container 20A, and the other end The portion protrudes outward from the peripheral edge seal portion 23 . The attachment positions of the two tabs 80 constituting the terminals of the positive electrode layer 40 and the negative electrode layer 50 are not particularly limited.

The metal material forming the tab 80 is, for example, aluminum, nickel, copper, or the like. When the all-solid-state battery 10 is a lithium-ion secondary battery, the tab 80 connected to the positive electrode layer 40 is typically made of aluminum or the like, and the tab 80 connected to the negative electrode layer 50 is typically is composed of copper, nickel, or the like.

The left tab 80 is sandwiched between the

packaging materials

21 and 22 via the tab film 90 at the left end of the peripheral seal portion 23 . The right tab 80 is also sandwiched between the

packaging materials

21 and 22 via the tab film 90 at the right end of the peripheral seal portion 23 .

The tab film 90 is a so-called adhesive film, and is configured to adhere to both the

packaging materials

21, 22 and the tab 80 (metal). By interposing the tab film 90, even if the tab 80 and the innermost layers (heat-fusible resin layers) of the

packaging materials

21 and 22 are made of different materials, they can be fixed. The tab film 90 is previously fused and fixed to the tab 80 to be integrated, and the tab 80 to which the tab film 90 is fixed is sandwiched between the

packaging materials

21 and 22 and fused, so that these are integrated.

<2. Laminate Unit>
<2-1. Overall configuration>
As shown in FIG. 2, the laminate unit 30 includes a positive electrode layer 40, a negative electrode layer 50, a solid electrolyte layer 60 laminated between the positive electrode layer 40 and the negative electrode layer 50, an insulating film 70, including. The positive electrode layer 40 and the negative electrode layer 50 are alternately stacked vertically with the solid electrolyte layer 60 interposed therebetween. Charging and discharging of the all-solid-state battery 10 are performed by transfer of lithium ions between the positive electrode layer 40 and the negative electrode layer 50 via the solid electrolyte layer 60 . The number of positive electrode layers 40 and negative electrode layers 50 included in the laminate unit 30 can be arbitrarily selected. In this embodiment, the laminate unit 30 includes one positive electrode layer 40 and two negative electrode layers 50 . The laminate unit 30 may have two or more positive electrode layers 40 and may have three or more negative electrode layers 50 .

<2-2. Positive electrode layer>
The cathode layer 40 includes a cathode current collector 41 and cathode active material layers 42 and 43 formed on part of both surfaces of the cathode current collector 41 . The positive electrode current collector 41 is preferably composed of at least a material with high electrical conductivity. A highly conductive substance is, for example, a metal or an alloy containing at least one metal element of silver, palladium, gold, platinum, aluminum, copper, chromium, and nickel. The material forming the positive electrode current collector 41 may be a non-metal such as carbon. The shape of the positive electrode current collector 41 is, for example, foil-like, plate-like, mesh-like, nonwoven fabric-like, or foam-like. In this embodiment, the shape of the positive electrode current collector 41 is a rectangular foil shape.

The positive electrode active material layers 42 and 43 contain a positive electrode active material capable of transferring lithium ions and electrons. The positive electrode active material is not particularly limited as long as it is a material that can reversibly release and absorb lithium ions and transport electrons, and a known positive electrode active material that can be applied to the positive electrode layer of an all-solid lithium ion secondary battery can be used. can be done. The positive electrode active material layers 42 and 43 include a solid electrolyte that exchanges lithium ions with the positive electrode active material. The solid electrolyte is not particularly limited as long as it has lithium ion conductivity, and materials generally used for all-solid lithium ion secondary batteries can be used.

In the present embodiment, the positive electrode active material layers 42 and 43 are formed on both sides of the positive electrode current collector 41, but this is not restrictive, and either one of the positive electrode active material layers 42 and 43 is formed on the positive electrode current collector 41. may be formed on one side of the

On part of both surfaces of the positive electrode current collector 41, tab connecting portions 41A are formed on which the positive electrode active material layers 42 and 43 are not formed. The tip of the tab connection portion 41A is located on the right side of the right end of the negative electrode layer 50 and exposed from the end of the insulating film 70 . A portion of the tab connection portion 41A exposed from the insulating film 70 is electrically connected to, for example, the right tab 80 (see FIG. 1).

<2-3. Negative electrode layer>
The negative electrode layer 50 includes a negative current collector 51 and negative active material layers 52 and 53 formed on both sides of the negative current collector 51 . Materials exemplified as materials for forming the positive electrode current collector 41 can be used as the material for forming the negative electrode current collector 51 . As for the shape of the negative electrode current collector 51 , the shape exemplified as the shape of the positive electrode current collector 41 can be adopted. In this embodiment, the shape of the negative electrode current collector 51 is a rectangular foil shape.

The negative electrode active material layers 52 and 53 contain a negative electrode active material capable of transferring lithium ions and electrons. The negative electrode active material is not particularly limited as long as it is a material that can reversibly release and absorb lithium ions and transport electrons, and a known negative electrode active material that can be applied to the negative electrode layer of an all-solid lithium ion secondary battery can be used. can be done.

In the present embodiment, the negative electrode active material layers 52 and 53 are formed on both sides of the negative electrode current collector 51 , but this is not restrictive, and either one of the negative electrode active material layers 52 and 53 is formed on the negative electrode current collector 51 . may be formed on one side of the For example, when the negative electrode layer 50 is formed as the lowest layer in the stacking direction (vertical direction) of the laminate unit 30 , the positive electrode layer 40 facing the lowermost negative electrode layer 50 does not exist below the negative electrode layer 50 . Therefore, in the negative electrode layer 50 positioned at the bottom layer, the negative electrode active material layer 52 may be formed only on one surface on the upper side in the stacking direction.

A tab connection portion 51A where the negative electrode active material layers 52 and 53 are not formed is formed on part of both surfaces of the negative electrode current collector 51 . The tip of the tab connection portion 51A is located on the left side of the left end portion of the positive electrode layer 40 . The tab connection portion 51A is electrically connected to, for example, the left tab 80 (see FIG. 1).

<2-4. Solid electrolyte layer>
Solid electrolyte layer 60 is made of a material containing a solid electrolyte. The solid electrolyte is not particularly limited as long as it has lithium ion conductivity, and materials generally used for all-solid lithium ion secondary batteries can be used. When the all-solid-state battery 10 is an all-solid-state sodium-ion secondary battery, a known material having sodium-ion conductivity can be used as the solid electrolyte. When the all-solid battery 10 is an all-solid magnesium ion secondary battery, the solid electrolyte can be a known material having magnesium ion conductivity.

<2-5. Insulating film>
The laminated body unit 30 is manufactured by hot-pressing the laminated body 100 (see FIG. 8), for example, with a warm isostatic press in a bonding step described later. The laminate unit 30 may be manufactured by hot-pressing the laminate 100 using a flat plate press, a roll press, or the like. When the shape and area of the positive electrode layer 40 and the negative electrode layer 50 are substantially the same, there is a possibility that the outer peripheral edge portion of the positive electrode layer 40 and the outer peripheral edge portion of the negative electrode layer 50 contact each other in the bonding step, causing a short circuit. be. Therefore, it is preferable that one of the positive electrode layer 40 and the negative electrode layer 50 has a smaller area than the other. The area of the positive electrode layer 40 is the area of the positive electrode active material layers 42 and 43 in plan view. The area of the negative electrode layer 50 is the area of the negative electrode active material layers 52 and 53 in plan view. In the present embodiment, the area of the positive electrode current collector 41 in plan view is smaller than the area of the negative electrode current collector 51 , and the areas of the positive electrode active material layers 42 and 43 in plan view are the same as those of the negative electrode active material layers 52 and 53 . smaller than area. Generally, in the all-solid-state battery 10, when the all-solid-state battery 10 is viewed from above, the areas of the positive electrode active material layers 42 and 43 are the same as the areas of the negative electrode active material layers 52 and 53, or It is preferably smaller than the area of the

layers

52,53. Moreover, it is generally preferable to press a range corresponding to the portions where the positive electrode active material layers 42 and 43 are present as the portion of the all-solid-state battery 10 to be press-pressed at high pressure.

In order to suppress a short circuit between the positive electrode layer 40 and the negative electrode layer 50 during manufacturing, when one of the positive electrode layer 40 and the negative electrode layer 50 is configured to have a smaller area than the other, the outer peripheral end portion of the positive electrode layer 40 and the negative electrode layer 50 are formed. A step 200 (see FIG. 8) is formed between the layer 50 and the outer peripheral edge. For this reason, when the laminate 100 (FIG. 8) is hot-pressed, there is a risk that, for example, the outer peripheral edge of the negative electrode layer 50 may be damaged at the step 200 . In the laminate unit 30 of the present embodiment, the insulating film 70 is arranged so as to fill the step 200 in order to prevent such a situation from occurring.

In this embodiment, the laminate unit 30 has two insulating films 70 . The laminate unit 30 may have one, or three or more insulating films 70 . Insulating film 70 is arranged along the outline of at least one of positive electrode layer 40 and negative electrode layer 50 so as to be bonded to at least one of positive electrode layer 40 and negative electrode layer 50 . In this embodiment, the insulating film 70 is arranged along the contour of the positive electrode layer 40 so as to join with the positive electrode layer 40 . The insulating film 70 may be arranged along at least part of the outer shell of the positive electrode layer 40 . In this embodiment, the insulating film 70 is arranged along the entire circumference of the outer shell of the positive electrode layer 40 . Therefore, since the insulating film 70 is arranged at a position corresponding to a wider area of the outer peripheral edge of the negative electrode layer 50 , the negative electrode layer 50 is less likely to be damaged during manufacturing of the laminate unit 30 .

3A is a plan view of the insulating film 70 before being joined to the positive electrode layer 40. FIG. The shape of the insulating film 70 can be arbitrarily selected. In this embodiment, the contour shape of the insulating film 70 is rectangular. The shape of the insulating film 70 may be a square or a polygon with pentagons or more. The insulating film 70 has a hole 70A penetrating through the insulating film 70 substantially in the center. The inner contour shape of the hole 70A is substantially the same shape as the outer contour shape of the positive electrode active material layers 42 and 43 . The area of hole 70A is slightly larger than the areas of positive electrode active material layers 42 and 43 . Therefore, when the positive electrode active material layers 42 and 43 are inserted into the hole 70A, a slight gap is formed between the inner shell of the hole 70A and the outer shell of the positive electrode active material layers 42 and 43 . By hot-pressing the laminate 100 shown in FIG. 8, a part of the layers constituting the insulating film 70 melts, and the gap between the inner shell of the hole 70A and the outer shell of the positive electrode active material layers 42 and 43 becomes be buried.

3B is a cross-sectional view showing an example of the layer structure of the insulating film 70. FIG. In this embodiment, the insulating film 70 is a laminated film including a first layer 71 and a second layer 72 laminated on the first layer 71 . The first layer 71 is a layer that does not substantially melt when the laminate 100 (see FIG. 8) is hot-pressed by a warm isostatic pressing machine in the bonding step described later. The second layer 72 is a layer that has the property of melting when hot pressed in the bonding process. In this embodiment, the insulating film 70 is laminated in order of the first layer 71 and the second layer 72 from the side closer to the solid electrolyte layer 60 . In the present embodiment, the first layer 71 and the second layer 72 partially overlap the solid electrolyte layer 60 in plan view. Therefore, for example, damage to the outer peripheral edge of the negative electrode layer 50 at the step 200 (see FIG. 8) can be preferably suppressed.

In the example shown in FIG. 2, the portion of the second layer 72 of the two insulating films 70 that partially covers the tab connection portion 41A is the outer peripheral edge of the positive electrode active material layer 42 and the positive electrode. It is joined to part of the surface of the current collector 41 . The portions of the second layers 72 of the two insulating films 70 other than the portion covering the tab connection portion 41A are the outer peripheral end portion of the positive electrode active material layer 43 and the outer peripheral end portion of the positive electrode current collector 41. is joined with

The material forming the first layer 71 and the material forming the second layer 72 are preferably different in at least one of melting point and melt mass flow rate. In this embodiment, the melting point is measured based on the provisions of JIS K7121:2012 (Method for measuring transition temperature of plastics (JIS K7121:1987 Supplement 1)). The melting point in this embodiment is synonymous with the melting temperature in JIS K7121. When there are multiple melting temperature peaks, the melting temperature with the maximum peak is taken as the melting temperature. The temperature rise is 10°C/min. The melting point is measured three times, and the average value of two melting points that are close to each other is used as the melting point. In this embodiment, the melting point is the endothermic peak measured by Differential Scanning Calorimetry. In this embodiment, the melt mass flow rate is a value at 190°C measured according to JIS K7210-1:2014 (ISO 1133-1:2011). In this embodiment, the material forming the first layer 71 has a higher melting point than the material forming the second layer 72 . Further, in the present embodiment, the material forming the first layer 71 has a lower melt mass flow rate at 190° C. than the material forming the second layer 72 . For this reason, when the laminate 100 shown in FIG. 8 is hot-pressed by a warm isostatic press, the second layer 72 preferably melts while the second layer 72 flows out. 71. Therefore, the insulating film 70 can be preferably arranged along the contour of the positive electrode layer 40 . Note that the melting point of the material forming the first layer 71 and the melting point of the material forming the second layer may be determined based on the temperature TA when the laminate 100 (see FIG. 8) is hot-pressed. preferable. The melting point of the material forming the first layer 71 is preferably higher than the temperature TA. The melting point of the material forming the second layer 72 is preferably lower than the temperature TA. The temperature TA is preferably determined based on the resistance and heat resistance of the solid electrolyte layer 60 . The higher the temperature TA, the lower the resistance of the solid electrolyte layer 60 can be. Therefore, the lower limit of the temperature TA is, for example, 20°C, preferably 80°C, more preferably 150°C, most preferably 185°C. On the other hand, if the temperature TA is too high, the performance of the solid electrolyte layer 60 will deteriorate. Therefore, the upper limit of the temperature TA is, for example, 250°C, preferably 195°C. Preferred ranges of temperature TA are, for example, 20°C to 250°C, 20°C to 195°C, 80°C to 250°C, 80°C to 195°C, 150°C to 250°C, 150°C to 195°C, 185°C to 250°C. , or between 185°C and 195°C.

The difference between the melting point of the material forming the first layer 71 and the melting point of the material forming the second layer 72 is preferably 50°C or more. The melting point of the material forming the second layer 72 is preferably 170° C. or lower. The melting point of the material forming the first layer 71 is preferably 250° C. or higher. The difference between the melt mass flow rate of the material forming the second layer 72 and the melt mass flow rate of the material forming the first layer 71 is preferably 0.8 g/10 min or more at 190°C. The melt mass flow rate of the material forming the second layer 72 is preferably 0.8 g/10 min or more at 190°C. The melt mass flow rate of the material forming the first layer 71 is preferably 0.1 g/10 min or less at 190°C.

The material forming the first layer 71 is preferably polyester, engineering plastic, or the like, for example. Examples of polyester include polyethylene naphthalate, polybutylene terephthalate, polyethylene terephthalate and the like.

The engineering plastic is, for example, a resin having a heat resistance temperature of 100° C. or higher, a tensile strength of 500 kgf/cm ² or higher, and a flexural modulus of 24000 kgf/cm ² or higher. Tensile strength is measured according to JIS K7161. The flexural modulus is measured according to JIS K7171. Engineering plastics are, for example, polyacetals, polyamides, polycarbonates, modified polyphenylene ethers, polybutylene terephthalate, GF-reinforced polyethylene terephthalate, ultra-high molecular weight polyethylene or syndiotactic polystyrene. Engineering plastics include super engineering plastics. Super engineering plastics have a high resistance to solvents, a heat resistance temperature of 150° C. or higher, and properties that allow them to be used for a long period of time. Super engineering plastics are amorphous polyarylates, polysulfones, polyethersulfones, polyphenylene sulfides, polyetheretherketones, polyimides, polyetherimides, fluororesins, or liquid crystal polymers.

The material forming the second layer 72 is preferably polyolefin or the like. Polyolefins are, for example, low-density polyolefins, medium-density polyolefins, high-density polyolefins, linear low-density polyolefins, or polypropylene. Moreover, in order to improve adhesion, these olefin materials may be acid-modified or silane-modified to have functional groups attached to their ends. Further, the material constituting the second layer 72 may be ethylene-vinyl-acetate, ionomer, polyvinyl butyral, silicone resin, polyurethane, or the like, in addition to polyolefin.

The all-solid-state battery 10 of this embodiment can be suitably used in an environment where it is constrained from the outside under high pressure. As the lower limit of the pressure that constrains the all-solid-state battery 10 from the outside, the pressure between the solid electrolyte layer 60 and the negative electrode active material layers 52 and 53 and between the solid electrolyte layer 60 and the positive electrode active material layers 42 and 43 are From the viewpoint of suitably suppressing peeling, the pressure is preferably about 0.1 MPa, more preferably about 0.5 MPa, even more preferably about 1 MPa, and even more preferably about 5 MPa. From a similar point of view, the upper limit of the pressure that constrains the all-solid-state battery 10 from the outside is preferably about 100 MPa, more preferably about 30 MPa, and even more preferably about 10 MPa. Preferable ranges of the pressure for restraining the all-solid-state battery 10 from the outside are about 0.1 to 100 MPa, about 0.1 to 30 MPa, about 0.1 to 10 MPa, about 0.5 to 100 MPa, and about 0.5 to 30 MPa. , about 0.5 to 10 MPa, about 1 to 100 MPa, about 1 to 30 MPa, about 1 to 10 MPa, about 5 to 100 MPa, about 5 to 30 MPa, and about 5 to 10 MPa.

As a method of restraining the all-solid-state battery 10 from the outside under high pressure, the all-solid-state battery 10 may be sandwiched between metal plates or the like and fixed in a state of being pressed under high pressure (for example, tightened with a vise), or gas pressurization may be used. method.

From the same point of view, the lower limit of the temperature when restraining the all-solid-state battery 10 from the outside is preferably 20° C., more preferably 40° C., and the upper limit is preferably 200° C., more preferably 200° C. 150° C. is preferred. A preferred temperature range for restraining the all-solid-state battery 10 from the outside is 20°C to 200°C, 20°C to 150°C, 40°C to 200°C, or 40°C to 150°C.

<3. Method for manufacturing all-solid-state battery>
An example of a method for manufacturing the all-solid-state battery 10 will be described with reference to FIGS. 4 to 8. FIG.
As shown in FIG. 4, the manufacturing method of the all-solid-state battery 10 includes a layer manufacturing process, a stacking process, a sealing process, and a bonding process.

In the layer manufacturing process of step S11, the positive electrode layer 40, the negative electrode layer 50, and the solid electrolyte layer 60 are manufactured. For the positive electrode layer 40 , for example, positive electrode slurry containing a positive electrode active material is applied to part of both surfaces of the positive electrode current collector 41 . Next, the positive electrode current collector 41 is cut into a desired size so as to include a portion coated with the positive electrode slurry and a portion not coated with the positive electrode slurry, that is, to include the tab connecting portion 41A. Thus, the positive electrode layer 40 is manufactured.

For the negative electrode layer 50, for example, negative electrode slurry containing a negative electrode active material is applied to part of both surfaces of the negative electrode current collector 51. Next, the negative electrode current collector 51 is cut into a desired size so as to include a portion coated with the negative electrode slurry and a portion not coated with the negative electrode slurry, that is, to include the tab connecting portion 51A. Thus, the negative electrode layer 50 is manufactured. Note that the negative electrode layer 50 may be manufactured prior to the positive electrode layer 40 in each layer manufacturing process.

For the solid electrolyte layer 60, for example, a solid electrolyte slurry containing a solid electrolyte is applied to one side of a base material made of any material. Next, the solid electrolyte layer 60 is manufactured by cutting the portion of the substrate coated with the solid electrolyte into a desired size.

Next, the solid electrolyte layer 60 is laminated on the negative electrode active material layers 52 and 53 of the negative electrode layer 50, and the base material is peeled off to manufacture the negative electrode layer 50 with the solid electrolyte layer 60 laminated thereon.

The lamination process of step S12 is performed after each layer manufacturing process. As shown in FIG. 5, in the lamination step, the insulating film 70 is placed on the negative electrode active material layer 52 of the negative electrode layer 50 on which the solid electrolyte layer 60 is laminated.

Next, as shown in FIG. 6, the positive electrode layer 40 is laminated on the negative electrode layer 50 by inserting the positive electrode active material layer 43 of the positive electrode layer 40 into the hole 70A of the insulating film 70 . Since the area of hole 70A is slightly larger than the area of positive electrode active material layers 42 and 43, in the state of FIG. A gap is formed.

Next, as shown in FIG. 7, the insulating film 70 is arranged such that the positive electrode active material layer 42 of the positive electrode layer 40 is inserted into the hole 70A of the insulating film 70, in other words, the positive electrode layer An insulating film 70 is placed around 40 . Next, as shown in FIG. 8, the anode layer 50 in which the solid electrolyte layer 60 is laminated on the cathode active material layer 42 of the cathode layer 40 is laminated to complete the laminate 100 . Tab 80 and tab film 90 are attached to laminate 100 after the lamination process.

The sealing process in step S13 is performed after the lamination process. In the sealing process, the laminate 100 with the tab 80 and tab film 90 attached is sealed, for example, by packaging materials 21, 22 (see FIG. 1). Portions of the tab 80 and tab film 90 are exposed from the wrapping

material

21,22.

The bonding process of step S14 is performed after the sealing process. In the joining step, the laminate 100 sealed with the

packaging materials

21 and 22 is hot-pressed by a warm isostatic press. By completing the bonding step, the positive electrode layer 40, the negative electrode layer 50, the solid electrolyte layer 60, and the insulating film 70 are bonded to each other, and the all-solid-state battery 10 is completed.

<4. Action and effect of all-solid-state battery>
According to the all-solid-state battery 10, since the insulating film 70 is arranged along the outer shell of the positive electrode layer 40 so as to join with the positive electrode layer 40 at the step 200, the laminate 100 is hot-pressed, and the negative electrode layer 50 The insulating film 70 functions like a cushion when pressure is applied to the outer peripheral edge of the . Since the outer peripheral edge of the negative electrode layer 50 is less likely to be damaged during manufacturing of the all-solid-state battery 10, short circuits are less likely to occur. Such an effect can be similarly obtained regardless of the form of the container 20A, for example, even if the container 20A is a metal can.

<5. Variation>
The above-described embodiments are examples of possible forms of the insulating film, all-solid battery, and method of manufacturing an all-solid battery according to the present invention, and are not intended to limit the forms. The insulating film, all-solid-state battery, and method for manufacturing an all-solid-state battery according to the present invention may take forms different from those illustrated in the embodiments. One example is a form in which part of the configuration of the embodiment is replaced, changed, or omitted, or a form in which a new configuration is added to the embodiment. Some examples of modifications of the embodiment are shown below.

<5-1>
In the above embodiment, the insulating film 70 has a two-layer structure of the first layer 71 and the second layer 72, but the specific layer structure of the insulating film 70 can be changed arbitrarily. For example, as shown in FIG. 9, the insulating film 70 may have the first layer 71 laminated on both sides of the second layer 72 . Moreover, as shown in FIG. 10, the first layer 71A and the second layer 72B of the insulating film 70 may be laminated in a direction orthogonal to the lamination direction (vertical direction) of the laminate unit 30 . Also, as shown in FIG. 11, the insulating film 70 may be laminated in order of a first layer 71 and a second layer 72 from the side closer to the positive electrode current collector 41 . Furthermore, as shown in FIG. 12, the insulating film 70 may have the second layers 72 laminated on both sides of the first layer 71 .

<5-2>
In the above embodiment, the area of the positive electrode current collector 41 in plan view is smaller than the area of the negative electrode current collector 51, and the areas of the positive electrode active material layers 42 and 43 in plan view are the same as those of the negative electrode active material layers 52 and 53. Although it was smaller than the area, these magnitude relationships may be reversed. That is, the area of the positive electrode current collector 41 in plan view is larger than the area of the negative electrode current collector 51, and the areas of the positive electrode active material layers 42 and 43 in plan view are larger than the areas of the negative electrode active material layers 52 and 53. It can be big. In this modification, the insulating film 70 is preferably arranged along at least a portion of the outer contour of the negative electrode layer 50 so as to join with the negative electrode layer 50 .

<5-3>
In the above embodiment, the method for manufacturing the all-solid-state battery 10 can be arbitrarily changed. For example, after the lamination step, without attaching the tab 80 and the tab film 90 to the laminate 100, the laminate 100 may be once sealed with an arbitrary packaging material, and the joining step may be performed. After the bonding process, an arbitrary packaging material is opened, a tab 80 and a tab film 90 are attached to the laminate 100, and the laminate 100 is sealed with the packaging materials 21 and 22 (see FIG. 1) to form an all-solid-state battery. 10 may be manufactured. Further, in each layer manufacturing process, the positive electrode layer 40 and the negative electrode layer 50 on which the solid electrolyte layer 60 is laminated may be densified in advance. , the negative electrode layer 50 laminated with the solid electrolyte layer 60 may be densified.

As another example, in the above embodiment, the bonding process may be performed after the lamination process and before the sealing process. In this variation, the bonding process preferably densifies the laminate 100 by hot roll pressing or hot plate pressing in a low dew point environment.

<6. Example>
The inventors of the present application manufactured all-solid-state batteries of Examples and Comparative Examples, and conducted tests to confirm whether or not they could be charged and discharged. In the following, for convenience of explanation, the same elements as in the embodiment among the elements constituting the all-solid-state batteries of the examples and the comparative examples may be given the same reference numerals as in the embodiment.

FIG. 13 is a table showing the specifications and test results of the all-solid-state batteries 10 of Examples 1-6 and Comparative Examples 1-3. The MFR (melt mass-flow rate) of the first layer and the MFR of the second layer in FIG. 13 are the values at 190°C. The all-solid-state battery 10 of Comparative Example 1 does not include the insulating film 70 . The insulating film 70 of the all-solid-state battery 10 of Comparative Example 2 has only the first layer 71 . The first layer 71 does not melt under the hot press conditions of the bonding process. Therefore, as shown in FIG. 14, in the laminate unit 30 of the all-solid-state battery 10 of Comparative Example 2, the insulating film 70 and the positive electrode layer 40 are not bonded. The insulating film 70 of the all-solid-state battery 10 of Comparative Example 3 has only the second layer 72 . The second layer 72 melts almost entirely under the hot press conditions of the bonding process. Therefore, as shown in FIG. 15 , in the laminate unit 30 of the all-solid-state battery 10 of Comparative Example 3, the second layer 72 of the insulating film 70 flows out substantially entirely, so that the outer shell of the positive electrode layer 40 not placed along Therefore, in the laminate unit 30 of the all-solid-state battery 10 of Comparative Example 3, the end of the positive electrode layer 40 and the end of the negative electrode layer 50 come into contact with each other, or a large pressure acts on the step 200, and the positive electrode layer A short circuit occurs when at least one of the end of the electrode 40 and the end of the negative electrode layer 50 is damaged. Note that FIG. 15 shows an example of a state in which the end portion of the negative electrode layer 50 is damaged.

In this test, the all-solid-state batteries 10 of Examples 1 to 6 and Comparative Examples 1 to 3 were restrained with a pressure of 0.2 tons/cm ² . This all-solid-state battery 10 was charged at a voltage of 4.35 V and discharged at a voltage of 3.0 V at an ambient temperature of 25° C. and a 0.1 C rate. In this test, three each of the all-solid-state batteries 10 of Examples 1 to 6 and Comparative Examples 1-3, that is, a total of 27 all-solid-state batteries 10 were created, and for the 27 all-solid-state batteries 10, Each charge and discharge was performed three times. For each of the all-solid-state batteries 10 of Examples 1 to 6 and Comparative Examples 1 to 3, a case where all three batteries could be charged three times and discharged three times was evaluated as "◯". . For each of the all-solid-state batteries 10 of Examples 1 to 6 and Comparative Examples 1 to 3, a case where charging and discharging could not be performed at least once was evaluated as "x".

As shown in FIG. 13, it was confirmed that all three of Examples 1 to 6, which include the insulating films 70 of the embodiment and modification, can be charged and discharged three times each. On the other hand, all three solid-state batteries 10 of Comparative Example 1 could not be charged and discharged even once. This is presumably because the all-solid-state battery 10 of Comparative Example 1 did not include the insulating film 70, and thus the outer peripheral edge of the negative electrode layer 50 was damaged during hot pressing in the bonding step. In addition, as with the all-solid-state battery 10 of Comparative Example 1, all three of the all-solid-state batteries 10 of Comparative Examples 2 and 3 could not be charged or discharged even once. This is because, in the all-solid-state battery 10 of Comparative Example 2, the positive electrode active material layers 42 and 43, the negative electrode active material layers 52 and 53, the positive electrode active material layers 52 and 53, and the positive electrode active material layers 52 and 53 are placed between the inner shell of the hole 70A and the outer shell of the positive electrode active material layers 42 and 43. It is believed that the current collector 41 and the negative electrode current collector 51 entered into the positive electrode active material layers 42 and 43, the negative electrode active material layers 52 and 53, and the solid electrolyte layer 60, thereby causing a short circuit. be done. This is probably because, in the all-solid-state battery 10 of Comparative Example 3, almost the entire second layer 72 flowed out and the insulating film 70 disappeared when hot-pressed in the bonding step.

10: All-solid battery 21: Packaging material 22: Packaging material 40: Positive electrode layer 50: Negative electrode layer 60: Solid electrolyte layer 70: Insulating film 71: First layer 72: Second layer 100: Laminate

Claims

An insulating film used in an all-solid-state battery,
The all-solid-state battery includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer,
the insulating film is arranged along an outline of at least one of the positive electrode layer and the negative electrode layer so as to be bonded to at least one of the positive electrode layer and the negative electrode layer;
comprising a first layer and a second layer laminated to the first layer;
At least one of a melting point and a melt mass flow rate is different between a material forming the first layer and a material forming the second layer. An insulating film.
The material forming the first layer has a higher melting point than the material forming the second layer,
The insulating film according to claim 1, wherein the melting point of the material forming the second layer is 170°C or lower.
The material forming the first layer has a higher melting point than the material forming the second layer,
The insulating film according to claim 1 or 2, wherein the material forming the first layer has a melting point of 250°C or higher.
The material forming the first layer has a higher melting point than the material forming the second layer,
The insulating film according to claim 1 or 2, wherein the difference between the melting point of the material forming the first layer and the melting point of the material forming the second layer is 50°C or more.
The material forming the first layer has a lower melt mass flow rate at 190° C. than the material forming the second layer,
The insulating film according to claim 1 or 2, wherein the material constituting the second layer has a melt mass flow rate of 0.8 g/10 min or more at 190°C.
The material forming the first layer has a lower melt mass flow rate at 190° C. than the material forming the second layer,
The insulating film according to claim 1 or 2, wherein the material constituting the first layer has a melt mass flow rate of 0.1 g/10 min or less at 190°C.
The material forming the first layer has a lower melt mass flow rate at 190° C. than the material forming the second layer,
The difference between the melt mass flow rate of the material forming the second layer and the melt mass flow rate of the material forming the first layer is 0.8 g/10 min or more at 190°C. insulating film.
An insulating film used in an all-solid-state battery,
The all-solid-state battery includes a positive electrode layer, a negative electrode layer, and a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer,
the insulating film is arranged along an outline of at least one of the positive electrode layer and the negative electrode layer so as to be bonded to at least one of the positive electrode layer and the negative electrode layer;
comprising a first layer and a second layer laminated to the first layer;
The material constituting the first layer includes polyester or engineering plastic,
A material constituting the second layer contains polyolefin. An insulating film.
An all-solid battery comprising the insulating film according to claim 1 or 2.
A method for manufacturing an all-solid-state battery comprising the insulating film according to claim 1 or 2,
The all-solid-state battery is
a positive electrode layer;
a negative electrode layer;
a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer;
the insulating film arranged along the contour of at least one of the positive electrode layer and the negative electrode layer so as to be bonded to at least one of the positive electrode layer and the negative electrode layer;
a stacking step of manufacturing a laminate by stacking the positive electrode layer, the negative electrode layer, and the solid electrolyte layer such that the solid electrolyte layer is arranged between the positive electrode layer and the negative electrode layer;
A joining step of joining the laminate by hot-pressing the laminate, which is performed after the lamination step;
A sealing step that is performed before or after the bonding step and seals the laminate with a packaging material,
In the lamination step, the insulating film is arranged around at least one of the positive electrode layer and the negative electrode layer.
a positive electrode layer;
a negative electrode layer;
a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer;
and an insulating film arranged along an outer shell of at least one of the positive electrode layer and the negative electrode layer so as to be bonded to at least one of the positive electrode layer and the negative electrode layer, wherein ,
a stacking step of manufacturing a laminate by stacking the positive electrode layer, the negative electrode layer, and the solid electrolyte layer such that the solid electrolyte layer is arranged between the positive electrode layer and the negative electrode layer;
A joining step of joining the laminate by hot-pressing the laminate, which is performed after the lamination step;
A sealing step that is performed before or after the bonding step and seals the laminate with a packaging material,
In the lamination step, the insulating film is arranged around at least one of the positive electrode layer and the negative electrode layer,
The insulating film includes a first layer and a second layer laminated on the first layer,
A method for manufacturing an all-solid-state battery, wherein at least one of a melting point and a melt mass flow rate is different between a material forming the first layer and a material forming the second layer.
a positive electrode layer;
a negative electrode layer;
a solid electrolyte layer disposed between the positive electrode layer and the negative electrode layer;
an insulating film arranged along an outer shell of at least one of the positive electrode layer and the negative electrode layer so as to be bonded to at least one of the positive electrode layer and the negative electrode layer.
The insulating film includes a first layer and a second layer laminated on the first layer,
the second layer is arranged along the outline of at least one of the positive electrode layer and the negative electrode layer;
The all-solid battery according to claim 12, wherein the first layer is arranged at least partly between the solid electrolyte layer and the negative electrode layer or the positive electrode layer.
The all-solid-state battery according to claim 12 or 13, wherein the insulating film is arranged so as to partially overlap the solid electrolyte layer in plan view.