Battery and method for manufacturing battery

Abstract

To improve reliability of a battery.SOLUTION: A battery 1 includes an exterior film 20 having a sealed space and a power generating element 10 disposed in the sealed space. The exterior film 20 has a bonding portion 21 which is a portion where portions of the exterior film 20 overlap and are bonded. The bonding portion 21 has a first main surface located in the sealed space. At least one of the power generating element 10 and the sealing space has a tapered shape in which a width in a first direction orthogonal to a stacking direction of the power generating element 10 is narrowed along a second direction orthogonal to the first direction and the stacking direction.SELECTED DRAWING: Figure 1A

Description

[Technical Field]

[0001] The present disclosure relates to batteries and methods for manufacturing batteries. [Background technology]

[0002] Patent Document 1 discloses an exterior body having a built-in seal portion in which the edges of upper and lower laminate films are folded inward.

[0003] Patent Document 2 discloses a battery in which the inner angle of the power generating element and the inner angle of the storage section of the battery case are both less than 90 degrees. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-175848 [Patent Document 2] Special Publication No. 2016-501422 Summary of the Invention [Problem to be solved by the invention]

[0005] There is room for improvement in terms of reliability compared to the above-mentioned conventional technology.

[0006] Therefore, the present disclosure provides a battery and a method for manufacturing the battery that can improve reliability. [Means for solving the problem]

[0007] A battery according to one embodiment of the present disclosure comprises an exterior film having a sealed space and a power generating element disposed within the sealed space, wherein the exterior film has a first joint where portions of the exterior film are overlapped and joined, the first joint having a first main surface located within the sealed space, and at least one of the power generating element and the sealed space having a tapered shape in which the width in a first direction perpendicular to the stacking direction of the power generating element narrows along a second direction perpendicular to the first direction and the stacking direction.

[0008] A method for manufacturing a battery according to one embodiment of the present disclosure includes the steps of preparing a cylindrical exterior film having a joint where portions of the exterior film overlap and are joined together, and inserting a power generating element into an internal space of the exterior film, wherein the joint has a main surface located within the internal space, and at least one of the power generating element and the internal space has a tapered shape in which the width in a first direction perpendicular to the stacking direction of the power generating element narrows along a second direction perpendicular to the first direction and the stacking direction. [Effects of the Invention]

[0009] According to the present disclosure, the reliability of the battery can be improved. [Brief explanation of the drawings]

[0010] [Figure 1A] FIG. 1A is a plan view of a battery according to Embodiment 1. FIG. [Figure 1B] FIG. 1B is a cross-sectional view of the battery taken along line IB-IB in FIG. 1A. [Figure 1C] FIG. 1C is a cross-sectional view of the battery taken along line IC-IC in FIG. 1A. [Figure 2A] FIG. 2A is a cross-sectional view of a battery according to Modification 1 of Embodiment 1. FIG. [Figure 2B] FIG. 2B is a cross-sectional view of a battery according to Modification 2 of Embodiment 1. As shown in FIG. [Figure 2C] FIG. 2C is a cross-sectional view of a battery according to Modification 3 of Embodiment 1. As shown in FIG. [Figure 2D]FIG. 2D is a cross-sectional view of a battery according to Variation 4 of Embodiment 1. As shown in FIG. [Figure 3A] FIG. 3A is a plan view of a battery according to embodiment 2. FIG. [Figure 3B] FIG. 3B is a cross-sectional view of the battery taken along line IIIB-IIIB in FIG. 3A. [Figure 3C] FIG. 3C is a cross-sectional view of the battery taken along line IIIC-IIIC in FIG. 3A. [Figure 4] FIG. 4 is a cross-sectional view of a battery according to a modification of the second embodiment. [Figure 5A] FIG. 5A is a plan view of a battery according to embodiment 3. FIG. [Figure 5B] FIG. 5B is a cross-sectional view of the battery taken along line VB-VB in FIG. 5A. [Figure 6] FIG. 6 is a cross-sectional view of a battery according to a modification of the third embodiment. [Figure 7A] FIG. 7A is a plan view of a battery according to embodiment 4. FIG. [Figure 7B] FIG. 7B is a cross-sectional view of the battery taken along line VIIB-VIIB in FIG. 7A. [Figure 7C] FIG. 7C is a side view of the battery according to embodiment 4. FIG. [Figure 8A] FIG. 8A is a cross-sectional view showing an example of a power generating element included in a battery according to Embodiment 4. FIG. [Figure 8B] FIG. 8B is a cross-sectional view showing another example of a power generating element included in the battery according to embodiment 4. As shown in FIG. [Figure 9A] FIG. 9A is a plan view of an extraction electrode included in the batteries according to each embodiment and each modification. [Figure 9B] FIG. 9B is a side view of an extraction electrode included in the batteries according to each of the embodiments and modifications. [Figure 10A] FIG. 10A is a diagram showing examples of combinations of the shapes of the power generating element and the internal space according to each embodiment and each modification. [Figure 10B] FIG. 10B is a diagram showing another example of a combination of the shapes of the power generating element and the internal space according to each embodiment and each modification. [Figure 10C] FIG. 10C is a diagram showing another example of a combination of the shapes of the power generating element and the internal space according to each embodiment and each modification. [Figure 10D] FIG. 10D is a diagram showing another example of a combination of the shapes of the power generating element and the internal space according to each embodiment and each modification. [Figure 10E] FIG. 10E is a diagram showing another example of a combination of the shapes of the power generating element and the internal space according to each embodiment and each modification. [Figure 10F] FIG. 10F is a diagram showing another example of a combination of the shapes of the power generating element and the internal space according to each embodiment and each modification. [Figure 11A] FIG. 11A is a cross-sectional view showing an example of a battery cell included in the batteries according to the embodiments and modifications. [Figure 11B] FIG. 11B is a cross-sectional view showing another example of a battery cell included in the batteries according to the embodiments and modifications. [Figure 11C] FIG. 11C is a cross-sectional view showing another example of a battery cell included in the batteries according to the embodiments and modifications. [Figure 12] FIG. 12 is a flowchart showing a method for manufacturing a battery according to each embodiment and each modification. [Figure 13A] FIG. 13A is a flowchart showing an example of a preparation step of an exterior film in the manufacturing method of the battery according to each embodiment and each modification. [Figure 13B] FIG. 13B is a flowchart showing another example of the exterior film preparation step in the battery manufacturing method according to each embodiment and each modification. DETAILED DESCRIPTION OF THE INVENTION

[0011] (Summary of the Disclosure) In batteries, the power generating element is enclosed in an exterior film to protect the power generating element. The encapsulation of the power generating element is achieved by forming a sealing portion around the power generating element. The sealing portion is formed by joining the overlapping portions of the exterior film by heat fusion or the like. The sealing portion can also be called a joining portion or a heat fusion portion.

[0012] Generally, the sealing portion is formed with the power generating element disposed within the exterior film. Therefore, as in the battery disclosed in Patent Document 2, the sealing portion is formed outside the sealed space in which the power generating element is disposed. However, because the sealing portion is formed with the power generating element disposed within the exterior film, there is a risk that the heat of heat fusion used to form the sealing portion will degrade the performance of the power generating element.

[0013] Alternatively, a built-in seal portion can be provided on the internal space side as a sealing portion, as in the battery disclosed in Patent Document 1. However, there is a risk that the built-in seal portion may come into contact with and be damaged when the power generating element is inserted.

[0014] As described above, conventional batteries are required to have improved reliability. Therefore, the present disclosure provides a battery and a method for manufacturing the battery that can achieve improved reliability.

[0015] A battery according to a first aspect of the present disclosure comprises an exterior film having a sealed space and a power generating element disposed within the sealed space, wherein the exterior film has a first joint where portions of the exterior film are overlapped and joined together, the first joint having a first main surface located within the sealed space, and at least one of the power generating element and the sealed space having a tapered shape in which the width in a first direction perpendicular to the stacking direction of the power generating element narrows along a second direction perpendicular to the first direction and the stacking direction.

[0016] This improves reliability. Specifically, because at least one of the power generating element and the sealed space has a tapered shape, the end of the power generating element is less likely to come into contact with the inner surface of the exterior film and the first bonding portion when the power generating element is inserted. This reduces damage to the end of the power generating element, thereby improving the reliability of the battery.

[0017] In the battery according to this embodiment, the first main surface of the first bonding portion is located within the sealed space, thereby improving the area efficiency of the battery compared to when the first main surface is located outside the sealed space. In this specification, area efficiency is expressed as the ratio of the power generating element to the projected area of the battery. The projection direction here is a direction perpendicular to the main surface of the battery. Furthermore, the sealed space refers to the space inside the exterior film that is sealed and separated from the outside.

[0018] Generally, in order to increase the area efficiency, it is expected that the projected area of the sealing portion located outside the sealed space will be reduced. For example, the area of the sealing portion can be reduced by shortening the width of the sealing portion or by folding the sealing portion. The width of the sealing portion corresponds to the shortest distance from the sealed space in the exterior film to the outside of the exterior film. Therefore, if the width of the sealing portion is shortened, the sealing performance will be reduced and the possibility of foreign matter such as moisture entering the sealed space will increase. Furthermore, if the sealing portion is folded, there is a higher possibility that an external force will be applied to the power generating element during the folding process, causing damage.

[0019] In contrast, in the battery according to this embodiment, as described above, the first main surface of the first joint portion is located within the sealed space, thereby improving the area efficiency of the battery compared to when the first main surface is located outside the sealed space. Furthermore, because the first joint portion can be formed before inserting the power-generating element into the internal space of the exterior film, folding and heat sealing after inserting the power-generating element are unnecessary. This reduces the likelihood of excessive external force and thermal load being applied to the power-generating element, thereby preventing deterioration in the quality of the power-generating element and improving the reliability of the battery.

[0020] A battery according to a second aspect of the present disclosure is the battery according to the first aspect, wherein the first joint has a second main surface opposite the first main surface, and the second main surface is located outside the exterior film.

[0021] This allows the first joint portion to be used as a wall separating the sealed space from the outside of the exterior film. This allows a larger sealed space to be secured, further reducing the possibility of damage to the edges when inserting the power generating element. This improves the mechanical reliability of the battery. Furthermore, since the first joint portion is where the exterior film overlaps, it is thicker than other portions. Therefore, by using the first joint portion as a wall separating the sealed space from the outside of the exterior film, the structural strength of the exterior film is increased. This improves the mechanical reliability of the battery.

[0022] A battery according to a third aspect of the present disclosure is the battery according to the first aspect, wherein the first joint has a second main surface opposite the first main surface, and the second main surface is located within the sealed space.

[0023] This allows the first bonding portion to be located inside the sealed space, thereby improving the area efficiency of the battery.

[0024] A battery according to a fourth aspect of the present disclosure is the battery according to the first aspect, wherein the first joint has a second main surface opposite the first main surface, and the second main surface is joined to a part of the exterior film other than the first joint.

[0025] By joining the first bonding portion to the inner surface of the exterior film, the structural strength of the exterior film can be increased, thereby improving the mechanical reliability of the battery.

[0026] A battery according to a fifth aspect of the present disclosure is the battery according to any one of the first to fourth aspects, wherein the power generating element has a quadrangular shape in plan view.

[0027] This allows the shape of the power generating element in plan view to be simple, further reducing the possibility of damage to the end portion when the power generating element is inserted.

[0028] A battery according to a sixth aspect of the present disclosure is the battery according to the fifth aspect, wherein the power generating element has a trapezoidal shape in plan view.

[0029] This allows the power generating element to have a tapered shape in plan view, such as an isosceles trapezoid, which reduces the possibility of damage to the end portion of the power generating element when inserted. It also reduces the occurrence of localized defects in the power generating element.

[0030] A battery according to a seventh aspect of the present disclosure is the battery according to any one of the first to sixth aspects, wherein the width of the first joint portion is 3 mm or more.

[0031] This ensures a long width for the first joint portion, which makes it possible to prevent foreign matter such as moisture from entering the sealed space, thereby improving the reliability of the battery.

[0032] A battery according to an eighth aspect of the present disclosure is the battery according to any one of the first to seventh aspects, wherein the gradient angle of the tapered shape is 0.25 degrees or more.

[0033] This reduces the possibility of damage to the end portion when the power generating element is inserted, thereby improving the reliability of the battery.

[0034] A battery according to a ninth aspect of the present disclosure is the battery according to any one of the first to eighth aspects, wherein the gradient angle of the tapered shape is 10 degrees or less.

[0035] This reduces the area in the sealed space where no power generating elements are disposed, thereby improving the area efficiency of the battery.

[0036] A battery according to a tenth aspect of the present disclosure is the battery according to any one of the first to ninth aspects, wherein the power generating element and the first joint overlap in a plan view of the power generating element.

[0037] This increases the structural strength of the exterior film in the area facing the main surface of the power generating element, thereby improving the mechanical reliability of the battery.

[0038] A battery according to an eleventh aspect of the present disclosure is a battery according to any one of the first to tenth aspects, wherein the exterior film has a second joint portion located at the end in the second direction and where parts of the exterior film are overlapped and joined, and the second joint portion has a third main surface located within the sealed space.

[0039] As a result, the third main surface of the second bonding portion is located within the sealed space, thereby improving the area efficiency of the battery compared to when the third main surface is located outside the sealed space. Furthermore, because the second bonding portion can be formed before inserting the power-generating element into the internal space of the exterior film, folding and heat sealing after inserting the power-generating element are unnecessary. This reduces the application of excessive external force and thermal load to the power-generating element, suppressing deterioration in the quality of the power-generating element and improving the reliability of the battery.

[0040] A battery according to a twelfth aspect of the present disclosure is the battery according to the eleventh aspect, wherein the second joint has a fourth main surface opposite the third main surface, and the fourth main surface is located outside the exterior film.

[0041] This allows the second joint to be used as a wall separating the sealed space from the outside of the exterior film. This allows a larger sealed space to be secured, further reducing the possibility of damage to the edges when inserting the power generating element. This improves the mechanical reliability of the battery. In addition, since the second joint is where the exterior film overlaps, it is thicker than other parts. Therefore, by using the second joint as a wall separating the sealed space from the outside of the exterior film, the structural strength of the exterior film is increased. This improves the mechanical reliability of the battery.

[0042] A battery according to a thirteenth aspect of the present disclosure is the battery according to the eleventh or twelfth aspect, wherein the power generating element and the second joint overlap in a plan view of the power generating element.

[0043] This increases the structural strength of the exterior film in the area facing the main surface of the power generating element, thereby improving the mechanical reliability of the battery.

[0044] A method for manufacturing a battery according to a fourteenth aspect of the present disclosure includes the steps of preparing a cylindrical exterior film having a joint where portions of the exterior film are overlapped and joined together, and inserting a power generating element into an internal space of the exterior film, wherein the joint has a main surface located within the internal space, and at least one of the power generating element and the internal space has a tapered shape in which the width in a first direction perpendicular to the stacking direction of the power generating element narrows along a second direction perpendicular to the first direction and the stacking direction.

[0045] This allows for the production of a highly reliable battery. Specifically, because at least one of the power-generating element and the internal space has a tapered shape, the end of the power-generating element is less likely to come into contact with the inner surface and joints of the exterior film when the power-generating element is inserted. This reduces damage to the end of the power-generating element, thereby improving the reliability of the battery.

[0046] Furthermore, by positioning the main surface of the joint within the internal space, the area efficiency of the battery can be improved compared to when the main surface is positioned outside the internal space. Furthermore, since the joint can be formed before inserting the power-generating element into the internal space of the exterior film, folding and heat sealing after inserting the power-generating element are not required. This reduces the application of excessive external force and thermal load to the power-generating element, thereby suppressing deterioration in the quality of the power-generating element and improving the reliability of the battery.

[0047] A battery manufacturing method according to a fifteenth aspect of the present disclosure is a battery manufacturing method according to the fourteenth aspect, wherein the preparing step includes a step of forming the joint by joining the first overlapping portion and the second overlapping portion of the first film and the second film, respectively, in a stacked state.

[0048] This allows two films to be stacked and joined together to easily form a cylindrical exterior film. This reduces equipment costs and improves productivity and mass production. It also reduces film loss when manufacturing large-sized batteries, for example. It also prevents the exterior film from forming bent portions other than at the joints, thereby increasing the structural strength of the exterior film and improving the reliability of the battery.

[0049] A battery manufacturing method according to a sixteenth aspect of the present disclosure is a battery manufacturing method according to the fourteenth aspect, in which the preparing step includes a step of forming the single film into a cylindrical shape so that portions of the film overlap each other, and joining the overlapping portions to form the joint.

[0050] This allows a cylindrical exterior film to be formed from a single sheet of film. Because the joint can be located in one place, the number of steps required for heat sealing and other processes to form the joint can be reduced. This simplifies the manufacturing process, improving productivity and mass production.

[0051] A battery manufacturing method according to a seventeenth aspect of the present disclosure is a battery manufacturing method according to any one of the fourteenth to sixteenth aspects, which includes, before the inserting step, a step of folding and joining portions of the exterior film together at the end portions in the second direction toward the internal space.

[0052] This allows the leading edge of the exterior film to be joined before inserting the power-generating element, eliminating the need for folding and heat sealing after inserting the power-generating element. This reduces the likelihood of excessive external force and thermal load being applied to the power-generating element, preventing deterioration in the quality of the power-generating element and improving the reliability of the battery. Furthermore, because the leading edge of the exterior film is folded inward, the area efficiency of the battery can be improved.

[0053] A battery manufacturing method according to an 18th aspect of the present disclosure is a battery manufacturing method according to any one of the 14th to 17th aspects, which includes, before the inserting step, a step of overlapping and joining portions of the exterior film at the end portions in the second direction so as to form a wall separating the internal space from the outside of the exterior film.

[0054] This allows the joint located at the tip of the exterior film to be used as a wall separating the internal space from the outside of the exterior film. This allows a large internal space to be secured, further reducing the possibility of damage to the end when inserting the power generating element. This improves the mechanical reliability of the battery. Furthermore, since the joint located at the tip of the exterior film is an overlapping portion of the exterior film, it is thicker than other portions, thereby increasing the structural strength of the exterior film. This improves the mechanical reliability of the battery.

[0055] A battery manufacturing method according to a 19th aspect of the present disclosure is a battery manufacturing method according to any one of the 14th to 18th aspects, which includes, after the inserting step, a step of sealing the rear end of the outer casing film in the second direction by sandwiching a lead connected to the power generating element.

[0056] This makes it possible to easily ensure electrical connection to the power generating element via the lead while maintaining the sealing of the power generating element.

[0057] A battery manufacturing method according to a twentieth aspect of the present disclosure is a battery manufacturing method according to any one of the fourteenth to nineteenth aspects, which includes, after the inserting step, a step of sealing the internal space in a reduced pressure atmosphere lower than atmospheric pressure.

[0058] This allows the exterior film and the power generating element to be tightly attached at atmospheric pressure, improving the volumetric efficiency of the battery. Furthermore, the amount of gases such as oxygen trapped in the internal space can be reduced, suppressing deterioration of the power generating element. This, in turn, improves the reliability of the battery.

[0059] Hereinafter, embodiments of the present disclosure will be specifically described with reference to the drawings.

[0060] The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection configurations, steps, and step sequences shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Furthermore, among the components in the following embodiments, components not described in independent claims are described as optional components.

[0061] Furthermore, each figure is a schematic diagram and is not necessarily an exact illustration. Therefore, for example, the scales of the figures do not necessarily match. Furthermore, in each figure, substantially the same components are given the same reference numerals, and redundant explanations are omitted or simplified.

[0062] Furthermore, in this specification, terms indicating the relationship between elements, such as parallel or perpendicular, terms indicating the shape of elements, such as quadrangle or trapezoid, and numerical ranges are not expressions that express only the strict meaning, but also expressions that include a substantially equivalent range, for example, a difference of about a few percent. For example, the corners of polygons such as quadrangles or trapezoids may be rounded or may have a chamfered shape.

[0063] In this specification and drawings, the x-axis, y-axis, and z-axis represent the three axes of a three-dimensional Cartesian coordinate system. In each embodiment, the z-axis direction is the stacking direction of the layers constituting the power generating element. When the power generating element or the exterior film has a rectangular shape in plan view, the y-axis direction is the direction parallel to one side of the rectangular shape. Furthermore, the negative x-axis direction is the insertion direction of the power generating element into the internal space of the exterior film. The y-axis direction is an example of the first direction, and the x-axis direction is an example of the second direction. The negative side of the x-axis is the leading end side of the second direction, and the positive side of the x-axis is the trailing end side of the second direction. In this specification, the positive side of the z-axis may be considered to be "upward" and the negative side of the z-axis may be considered to be "downward."

[0064] In this specification, unless otherwise specified, "planar view" refers to a view from a direction perpendicular to the main surface of the power-generating element (z-axis direction). In the case of a flat member such as a plate, layer, foil, or film, the "main surface" refers to the main surface of the member, for example, the surface with the largest area or the surface opposite to the surface with the largest area. The main surface is usually flat, but may include minute irregularities or curvatures. For example, since the joint is formed by heat fusion or the like, the main surface of the joint may not be strictly flat. The main surface of the joint is part of the main surface of the film.

[0065] Furthermore, in this specification, ordinal numbers such as "first" and "second" do not refer to the number or order of components unless otherwise specified, but are used to avoid confusion and distinguish between components of the same type.

[0066] In this specification, "inside the space" includes not only the space itself but also the inner surface of a member that forms the space. For example, the inner surface of an exterior film having a sealed space that faces the sealed space is considered to be located within the sealed space. Unless otherwise specified, the inside of the exterior film refers to the sealed space side, and the outside of the exterior film refers to the side opposite the sealed space side, i.e., the outside of the battery. Similarly, when the exterior film includes two or more films, the inside of one film refers to the sealed space side, and the outside of one film refers to the side opposite the sealed space, i.e., the outside of the battery. Similarly, when the internal space is not sealed during the battery manufacturing process, the inside of the exterior film or one film refers to the side of the internal space before sealing, and the outside of the exterior film or one film refers to the side opposite the internal space before sealing.

[0067] (Embodiment 1) The configuration of the battery according to the first embodiment will be described with reference to FIGS. 1A, 1B, and 1C. FIG. 1A is a plan view of the battery 1 according to the present embodiment. FIG. 1B is a cross-sectional view of the battery 1 taken along line IB-IB in FIG. 1A. FIG. 1C is a cross-sectional view of the battery 1 taken along line IC-IC in FIG. 1A. Note that in FIGS. 1B and 1C and other cross-sectional views, the thickness of each layer is exaggerated to make the layer structure of the battery 1 easier to understand.

[0068] 1A, 1B, and 1C, the battery 1 according to the present embodiment includes a power generating element 10 and an exterior film 20. As shown in Fig. 1A, the battery 1 also includes extraction electrodes 30 and 40. The battery 1 is an all-solid-state battery.

[0069] As shown in FIGS. 1B and 1C, the power generating element 10 is disposed in the internal space 50. The power generating element 10 is a flat plate-shaped power generating element containing a solid electrolyte. The power generating element 10 is an all-solid-state battery element that does not contain an electrolytic solution. Specifically, the power generating element 10 includes an electrode active material layer 110, a counter electrode active material layer 120, a solid electrolyte layer 130, an electrode current collector 140, and a counter electrode current collector 150. The specific configuration of the power generating element 10 will be described later.

[0070] In this embodiment, the shape of the power generating element 10 in a plan view is quadrangular. Specifically, as shown in Fig. 1A, the shape of the power generating element 10 in a plan view is rectangular. In Fig. 1A, the outline of the power generating element 10 is represented by a dashed line.

[0071] The exterior film 20 is a film member for sealing the power generating element 10. As shown in Figures 1B and 1C, the exterior film 20 has an internal space 50. The internal space 50 is an example of a sealed space, and is separated from the outside of the exterior film 20.

[0072] In this embodiment, the shape of the exterior film 20 in a planar view is a rectangle. Specifically, the shape of the exterior film 20 in a planar view is an isosceles trapezoid with two sides parallel to the y-axis direction as the upper and lower bases and two sides inclined with respect to the x-axis direction as the legs. The shape of the exterior film 20 in a planar view is substantially the same as the shape of the internal space 50. This makes it possible to reduce unnecessary portions of the exterior film 20 and improve the area efficiency of the battery 1.

[0073] 1A, exterior film 20 includes bonding portions 21 and 22 and sealing portions 23 and 24. Bonding portions 21 and 22 and sealing portions 23 and 24 are all examples of sealing portions for sealing internal space 50, and are portions where parts of exterior film 20 overlap and are joined together. Note that in FIG. 1A, bonding portions 21 and 22 and sealing portions 23 and 24 are each indicated by dotted shading to schematically represent the areas where each is provided.

[0074] 1B and 1C, exterior film 20 includes two films 25 and 26. Two films 25 and 26 are arranged on top of each other, and a sealing portion is formed in a ring shape around the periphery. Specifically, joining portions 21 and 22 and sealing portions 23 and 24 are formed as a ring-shaped sealing portion. As a result, a sealed internal space 50 is formed between film 25 and film 26.

[0075] Film 25 is an example of a first film. Film 25 is also called a laminate film and has a layered structure including two resin films and a metal layer sandwiched between the two resin films. The two resin films are primarily composed of a thermoplastic resin. The two resin films are formed using, for example, polyethylene terephthalate, polypropylene, or polyethylene. The two resin films may be formed using the same material, but may also be formed using different materials. The metal layer is formed using, for example, aluminum or nickel. By including the metal layer, film 25 can suppress the permeation of foreign substances such as moisture and oxygen. The thickness and material of the resin films and metal layer are appropriately selected based on the sealing performance, mechanical strength, and operating temperature range of battery 1.

[0076] Film 26 is an example of a second film. Film 26 has the same configuration as film 25, but may be different. For example, the resin film included in film 26 may be formed of a different material or have a different thickness from the resin film included in film 25. Also, for example, the metal layer included in film 26 may be formed of a different material or have a different thickness from the metal layer included in film 25.

[0077] The joints 21 and 22 are each an example of a first joint, which is a portion where parts of the exterior film 20 overlap and join together. In this embodiment, the joints 21 and 22 are formed by heat-sealing the resin films of the two films 25 and 26.

[0078] 1B, the joint 21 is a portion where an end 25a of the film 25 and an end 26a of the film 26 are overlapped and joined. The joint 21 has a main surface 21a and a main surface 21b opposite to the main surface 21a. The main surface 21a is located within the sealed internal space 50. The main surface 21a is an example of a first main surface and is part of the inner main surface of the exterior film 20. The main surface 21b is an example of a second main surface and is part of the inner main surface of the exterior film 20. The main surface 21b is joined to a part of the exterior film 20 other than the joint 21. Specifically, the main surface 21b is joined to the inner surface of the exterior film 20.

[0079] Joint 21 is formed by joining the outer principal surfaces of films 25 and 26 at their ends. Specifically, joint 21 is formed by folding end 25a of film 25 inward, overlapping film 26 with end 26a folded inward, and joining the outer principal surfaces of both films by thermal fusion, so as to protrude into interior space 50. Furthermore, joint 21 protruding inward is folded and joined to the inner surface of film 25 by thermal fusion. As a result, joint 21 is formed in which principal surface 21b is joined to the inner surface of film 25, as shown in FIG. 1B.

[0080] The joint 22 is formed by overlapping and joining the end 25b of the film 25 and the end 26b of the film 26. The structure and method of forming the joint 22 are the same as those of the joint 21. The joints 21 and 22 are formed before the power generating element 10 is inserted into the internal space 50.

[0081] 1A, the bonding portions 21 and 22 are provided along two opposing sides of the exterior film 20. In plan view, the bonding portions 21 and 22 are inclined at a predetermined angle with respect to the x-axis direction. This angle is the gradient angle of the tapered shape.

[0082] Sealing portions 23 and 24 are portions where parts of exterior film 20 overlap and are joined together. In the present embodiment, sealing portions 23 and 24 are formed by heat-sealing the resin films of two films 25 and 26.

[0083] 1C, sealing portion 23 is a portion where end 25c of film 25 and end 26c of film 26 are overlapped and joined. Sealing portion 24 is a portion where end 25d of film 25 and end 26d of film 26 are overlapped and joined.

[0084] The sealing portion 23 is formed by joining the inner principal surfaces of the films 25 and 26 at their ends. Specifically, the sealing portion 23 is formed so as to protrude outside the internal space 50 by joining the inner principal surfaces of the end 25c of the film 25 and the end 26c of the film 26 by heat sealing while the end 25c is overlapped without being folded. The sealing portion 23 is formed after the power-generating element 10 is inserted into the internal space 50. Alternatively, the sealing portion 23 may be formed after the joining portions 21 and 22 are formed and before the power-generating element 10 is inserted into the internal space 50.

[0085] The sealing portion 24 is formed by joining the inner principal surfaces of the films 25 and 26 at their ends. Specifically, the sealing portion 24 is formed so as to protrude outside the internal space 50 by joining the inner principal surfaces of the end portions 25d and 26d of the films 25 and 26 by heat fusion without folding the end portions 25d and 26d of the films 25 and 26, with the extraction electrodes 30 and 40 sandwiched between them. The sealing portion 24 is formed after the power generating element 10 is inserted into the internal space 50.

[0086] Note that the bonding portion 21 or 22 and the sealing portion 23 or 24 may partially overlap. For example, the bonding portions 21 and 22 may be formed so as to be continuous from the end on the negative side of the x-axis to the end on the positive side of the x-axis of the films 25 and 26 before the sealing portions 23 and 24 are formed. In this case, heat is also applied to the longitudinal ends of the bonding portions 21 and 22 when forming the sealing portions 23 and 24, so that the sealing portions 23 and 24 are formed so as to overlap the bonding portions 21 and 22, respectively. This improves the sealing performance of the internal space 50, thereby improving the reliability of the battery 1.

[0087] The extraction electrodes 30 and 40 are both electrode terminals for electrically connecting the power generating element 10 to an element external to the battery 1. The extraction electrode 30 is electrically connected to an electrode current collector 140 of the power generating element 10. The extraction electrode 40 is electrically connected to a counter electrode current collector 150 of the power generating element 10.

[0088] The specific configuration of the extraction electrodes 30 and 40 will be described later.

[0089] The internal space 50 is a sealed space for accommodating the power generating element 10. The internal space 50 can also be called a sealed space. In this embodiment, the internal space 50 is formed by being surrounded by the inner main surfaces of the two films 25 and 26, the bonding portions 21 and 22, and the sealing portions 23 and 24.

[0090] The sealed internal space 50 has a tapered shape in which the width in the y-axis direction narrows along the negative x-axis direction. The internal space 50 has a rectangular shape in plan view. Specifically, the internal space 50 has a trapezoidal shape in plan view. More specifically, the internal space 50 has an isosceles trapezoidal shape in plan view, with two sides parallel to the y-axis direction as upper and lower bases and two sides tilted with respect to the x-axis direction as legs.

[0091] The planar shape of the internal space 50 depends on the respective shapes of the joints 21 and 22 and the sealing portions 23 and 24. The sealing portions 23 and 24 correspond to the upper and lower bases of the isosceles trapezoid, respectively, and the joints 21 and 22 correspond to the legs of the isosceles trapezoid.

[0092] The bottom of the internal space 50 corresponds to the insertion opening for the power generating element 10. When the power generating element 10 is inserted, the internal space 50 is not sealed, and the exterior film 20 is formed in a cylindrical or bag-like shape. The cylindrical exterior film 20 is an exterior film in which the joining portions 21 and 22 are formed, but the sealing portions 23 and 24 are not formed. The bag-shaped exterior film 20 is an exterior film in which the joining portions 21 and 22 and the sealing portion 23 are formed, but the sealing portion 24 is not formed. The bag-shaped exterior film can also be called a cylindrical exterior film with a bottom.

[0093] The tapered shape of the internal space 50 makes it easier to ensure a distance between the end of the power generating element 10 and the joints 21 and 22 when the power generating element 10 is inserted, and makes it less likely that the end will come into contact with the inner surface of the exterior film 20 and the joints 21 and 22 when the power generating element 10 is inserted. Damage to the end of the power generating element 10 is suppressed, thereby improving the reliability of the battery 1.

[0094] As described above, in this embodiment, the joints 21 and 22 are disposed within the internal space 50, thereby improving the area efficiency of the battery 1. Furthermore, because the joints 21 and 22 can be formed before the power generating element 10 is inserted, the thermal load generated when the joints 21 and 22 are formed is not applied to the power generating element 10. This prevents deterioration in the quality of the power generating element 10. Furthermore, the distance between the joints 21 and 22 and the power generating element 10 can be reduced, thereby further improving the area efficiency of the battery 1. Furthermore, because the sealed internal space 50 has a tapered shape, damage caused by contact with the ends of the power generating element 10 during insertion can be prevented. Thus, this embodiment makes it possible to realize a battery 1 that achieves improved area efficiency and reliability.

[0095] Furthermore, in the battery 1 according to this embodiment, the joints 21 and 22 face the end faces of the power-generating element 10. For example, the width of the joints 21 and 22 is shorter than the thickness of the power-generating element 10. The width of the joint 21 is the distance along the joint surface between the end 25a of the film 25 and the end 26a of the film 26, and is the distance from the sealed internal space 50 to the outside of the battery 1. In the cross section shown in FIG. 1B , the width of the joint 21 is represented by the length of the joint 21 in the z-axis direction. The same applies to the width of the joint 22. This allows the battery 1 to be made thinner.

[0096] At least one of the joints 21 and 22 may be in contact with an end face of the power generating element 10. This allows the joints 21 and 22 to suppress movement of the power generating element 10. For example, when external vibrations are applied, the joints 21 and 22 that are in contact with the power generating element 10 can suppress movement of the power generating element 10. By suppressing movement of the power generating element 10 within the internal space 50, damage to the power generating element 10 can be suppressed, and the reliability of the battery 1 can be improved.

[0097] Next, several modifications of this embodiment will be described. The following description will focus on the differences from this embodiment, and the description of commonalities will be omitted or simplified.

[0098] <Variation 1> Fig. 2A is a cross-sectional view of a battery 1A according to Modification 1 of the present embodiment. The cross section shown in Fig. 2A corresponds to the cross section taken along line IB-IB in Fig. 1A.

[0099] 2A, compared to battery 1, battery 1A has joints 21A and 22A instead of joints 21 and 22. Joints 21A and 22A overlap with power-generating element 10 when viewed from the z-axis direction.

[0100] Specifically, bonding portions 21A and 22A are each bonded to the inner principal surface of film 26. Bonding portions 21A and 22A are located between the lower surface of power-generating element 10 and film 26. For example, principal surface 21a of bonding portion 21A is in contact with the lower surface of power-generating element 10. Principal surface 21b of bonding portion 21A is bonded to the inner principal surface of film 26. The same applies to bonding portion 22A.

[0101] According to this modification, the width of each of the joints 21A and 22A can be increased. For example, the width W of the joint 22A is 3 mm or more. The width W may be 5 mm or more, 7 mm or more, or 10 mm or more. The upper limit of the width W is, for example, 15 mm, but is not limited to this. The length of the width W is determined by the required moisture-proof performance, etc. The same applies to the width of the joint 21A. The width of the joint 21A may be the same as or different from the width of the joint 22A.

[0102] Increasing the width W can increase the creepage distance between the internal space 50 and the outside of the battery 1A via the joint surface of the joint 22A. This can prevent foreign matter such as moisture from entering the internal space 50 and suppress deterioration of the power generating element 10. This can further improve the reliability of the battery 1A.

[0103] Furthermore, the joints 21A and 22A function as walls separating the internal space 50 from the outside of the battery 1A, thereby increasing the structural strength of the exterior film 20 in the portion facing the underside of the power-generating element 10. This can improve the mechanical reliability of the battery 1A.

[0104] In this modification, at least one of the bonding portions 21A and 22A may be located between the upper surface of the power generating element 10 and the film 25. In other words, at least one of the bonding portions 21A and 22A may be bonded to the inner main surface of the film 25.

[0105] <Variation 2> Fig. 2B is a cross-sectional view of a battery 1B according to Modification 2 of the present embodiment. The cross-sectional view shown in Fig. 2B corresponds to the cross section taken along line IB-IB in Fig. 1A.

[0106] 2B, compared to battery 1, battery 1B has joints 21B and 22B instead of joints 21 and 22. Joints 21B and 22B overlap with power-generating element 10 when viewed from the z-axis direction.

[0107] In this modification, ends 26a and 26b of film 26 are not folded. Ends 25a and 25b of film 25 are folded and joined to film 26. Specifically, main surface 21b of joint 21B is located outside internal space 50, not inside internal space 50. In other words, main surface 21b of joint 21B is part of the outer main surface of exterior film 20.

[0108] Joint 21B is formed by joining the outer main surface of one of films 25 and 26 to the inner main surface of the other at their ends. Specifically, joint 21B is formed by folding end 25a of film 25 inward, overlapping end 26a of film 26 without folding it, and joining the outer main surface of end 25a to the inner main surface of end 26a by thermal fusion, so that main surface 21a is located within internal space 50. The configuration and formation method of joint 22B are the same as those of joint 21B.

[0109] According to this modification, the width of each of the joints 21B and 22B can be increased, as in the first modification. This prevents moisture and other foreign matter from entering the internal space 50, thereby suppressing deterioration of the power generating element 10. This further improves the reliability of the battery 1B.

[0110] Furthermore, because there is no need to fold ends 26a and 26b of film 26, it is possible to prevent a decrease in the structural strength of film 26. Furthermore, because joints 21B and 22B function as walls separating internal space 50 from the outside of battery 1B, the structural strength of exterior film 20 in the portion facing the underside of power-generating element 10 is increased, thereby improving the mechanical reliability of battery 1B.

[0111] <Variation 3> Fig. 2C is a cross-sectional view of a battery 1C according to Modification 3 of the present embodiment. The cross-sectional view shown in Fig. 2C corresponds to the cross section taken along line IB-IB in Fig. 1A.

[0112] As shown in FIG. 2C, battery 1C has bonding portions 21C and 22C instead of bonding portions 21 and 22 compared to battery 1. Bonding portions 21C and 22C are provided so as to protrude toward internal space 50 from near the center of power generating element 10 in the stacking direction. Principal surface 21b of bonding portion 21C is bonded to the inner surface of film 25, but may also be bonded to the inner surface of film 26, or may not be bonded to either film 25 or 26. Bonding portion 22C has the same configuration as bonding portion 21C.

[0113] Joints 21C and 22C are formed, for example, by stacking two films of the same size as films 25 and 26, folding the edges inward, and heat-sealing them. This means that there is no need to adjust the size of films 25 and 26 depending on the thickness of power-generating element 10. Therefore, this modification can improve the productivity and mass production of battery 1C.

[0114] <Variation 4> Fig. 2D is a cross-sectional view of a battery 1D according to Modification 4 of the present embodiment. The cross-sectional view shown in Fig. 2D corresponds to the cross section taken along line IB-IB in Fig. 1A.

[0115] As shown in FIG. 2D , battery 1D further includes a protective layer 60 compared to battery 1. The protective layer 60 is an insulating layer provided to protect the end faces of the power-generating element 10. The protective layer 60 is formed so as to cover the end faces of the power-generating element 10, for example, by applying or adhering an epoxy-based resin material thereto, or by other methods. The protective layer 60 covers all of the end faces of the power-generating element 10. This enhances the effect of suppressing damage to the end faces of the power-generating element 10, thereby achieving a more reliable battery 1D.

[0116] Alternatively, the protective layer 60 may cover only a portion of the end face of the power generating element 10. For example, the protective layer 60 may be provided so as to cover only the end face on the tip side in the insertion direction of the power generating element 10. This can suppress damage to the end face during insertion, and by reducing the projected area of the protective layer 60, it is possible to improve area efficiency. Furthermore, the protective layer 60 may be provided so as to cover only the four corners of the power generating element 10 that is rectangular in plan view. This can improve area efficiency while enhancing the effect of suppressing damage to the end face of the power generating element 10. The protective layer 60 may be provided so as to cover only the two corners on the tip side in the insertion direction out of the four corners of the power generating element 10 that is rectangular in plan view.

[0117] The protective layer 60 may be provided on the end face of the power generating element included in the battery according to the first embodiment and the first to third modifications, as well as the second to fourth embodiments and their respective modifications described below.

[0118] (Embodiment 2) Next, a second embodiment will be described.

[0119] The main difference between embodiment 2 and embodiment 1 is that the exterior film is made up of a single film. The following description will focus on the differences from embodiment 1, and explanation of the commonalities will be omitted or simplified.

[0120] Fig. 3A is a plan view of the battery 2 according to the present embodiment. Fig. 3B is a cross-sectional view of the battery 2 taken along line IIIB-IIIB in Fig. 3A. Fig. 3C is a cross-sectional view of the battery 2 taken along line IIIC-IIIC in Fig. 3A.

[0121] 3A, 3B, and 3C, battery 2 according to the present embodiment is different from battery 1 according to embodiment 1 in that it includes exterior film 220 instead of exterior film 20. Exterior film 220 differs from exterior film 20 in that it has only one joint.

[0122] 3A, exterior film 220 includes bonding portion 221 and sealing portions 223 and 224. Bonding portion 221 and sealing portions 223 and 224 are all examples of sealing portions for sealing internal space 50, and are portions where parts of exterior film 220 overlap and are bonded together.

[0123] 3B and 3C, in this embodiment, exterior film 220 includes one film 225. One film 225 is formed into a cylindrical shape around the x-axis, thereby forming cylindrical exterior film 220.

[0124] Film 225 is also called a laminate film and has a layered structure including two resin films and a metal layer sandwiched between the two resin films. The specific structure of film 225 is the same as that of film 25 or 26 according to the first embodiment.

[0125] Joint 221 is an example of a first joint, which is a portion where parts of exterior film 220 overlap and join together. In this embodiment, joint 221 is formed by heat-sealing parts of the resin film of film 225 together.

[0126] 3B, the joint 221 is a portion where the end 225a and the end 225b of the film 225 are overlapped and joined. The joint 221 has a main surface 221a and a main surface 221b opposite to the main surface 221a. The main surface 221a is located within the sealed internal space 50. The main surface 221a is an example of a first main surface and is part of the inner main surface of the exterior film 220. The main surface 221b is an example of a second main surface and is part of the outer main surface of the exterior film 220. In other words, the main surface 221b is located outside the internal space 50, not within the internal space 50.

[0127] Joint 221 is formed by joining the inner main surface of end 225a and the outer main surface of end 225b of film 225. Specifically, joint 221 is formed by forming film 225 into a cylindrical shape so that ends 225a and 225b of one film 225 overlap, and then joining the overlapped ends 225a and 225b.

[0128] As shown in FIG. 3A, the joint 221 is provided along one side of the exterior film 220. In a plan view, the joint 221 is inclined at a predetermined angle with respect to the x-axis direction. This angle is the gradient angle of the tapered shape. Of the four sides of the exterior film 220, the side opposite the side on which the joint 221 is provided, specifically the side located on the negative side of the y-axis, is also inclined at a predetermined angle with respect to the x-axis direction in a plan view. The side located on the negative side of the y-axis corresponds to a fold line of the film 225. In this embodiment, the exterior film 220 is formed by folding the film 225 so that the fold line forms a predetermined angle with respect to the x-axis direction.

[0129] Sealing portions 223 and 224 are portions where parts of exterior film 220 overlap and join together. In the present embodiment, sealing portions 223 and 224 are formed by heat-sealing parts of the resin film of one film 225 together.

[0130] 3C, sealing portion 223 is a portion where end 225c and end 225d of film 225 are overlapped and joined together. Sealing portion 224 is a portion where end 225e and end 225f of film 225 are overlapped and joined together.

[0131] The sealing portion 223 is formed by joining the inner principal surfaces of the ends 225c and 225d of the film 225. Specifically, the sealing portion 223 is formed so as to protrude outside the internal space 50 by joining the inner principal surfaces of the ends 225c and 225d of the film 225 by heat sealing while the ends are stacked without being folded. The sealing portion 223 is formed after the power-generating element 10 is inserted into the internal space 50. Alternatively, the sealing portion 223 may be formed after the joining portion 221 is formed and before the power-generating element 10 is inserted into the internal space 50.

[0132] The sealing portion 224 is formed by joining the inner principal surfaces of the ends 225e and 225f of the film 225 at the ends. Specifically, the sealing portion 224 is formed so as to protrude outside the internal space 50 by joining the inner principal surfaces of the ends 225e and 225f of the film 225 by heat fusion without folding them and overlapping them with the extraction electrodes 30 and 40 sandwiched between them. The sealing portion 224 is formed after the power generating element 10 is inserted into the internal space 50.

[0133] Note that the bonding portion 221 and the sealing portion 223 or 224 may partially overlap. For example, the bonding portion 221 may be formed so as to be continuous from the end on the negative side of the x-axis to the end on the positive side of the x-axis of the film 225 before the sealing portions 223 and 224 are formed. In this case, when the sealing portions 223 and 224 are formed, heat is also applied to the longitudinal ends of the bonding portion 221, so that the sealing portions 223 and 224 are each formed so as to overlap the bonding portion 221. This can improve the sealing performance of the internal space 50, thereby improving the reliability of the battery 2.

[0134] In this embodiment, as in the first embodiment, the internal space 50 has a tapered shape in which the width in the y-axis direction narrows along the negative x-axis direction. This makes it possible to suppress damage caused by contact with the end of the power generating element 10 when the power generating element 10 is inserted. As in the first embodiment, this embodiment makes it possible to realize a battery 2 that can improve area efficiency and reliability.

[0135] In addition, in this embodiment, the cylindrical exterior film 220 is formed from a single film 225. In this case, the joint 221 can be formed in one place, and therefore the number of steps such as heat fusion for forming the joint 221 can be reduced. This makes it possible to simplify the manufacturing process, and improve the productivity and mass production of the battery 2.

[0136] <Modification> Fig. 4 is a cross-sectional view of a battery 2A according to a modification of the present embodiment, which corresponds to the cross section taken along line IIIB-IIIB in Fig. 3A.

[0137] 4, the position of the joint 221 in the battery 2A is different from that in the battery 2. Specifically, the joint 221 overlaps with the power generating element 10 when viewed from the z-axis direction. More specifically, the main surface 221a of the joint 221 is in contact with the upper surface of the power generating element 10. The joint 221 may also be provided on the lower surface of the power generating element 10.

[0138] According to this modification, the width W of the joint 221 can be increased. For example, the width W of the joint 221 is 3 mm or more. The width W may be 5 mm or more, 7 mm or more, or 10 mm or more. The upper limit of the width W is, for example, 15 mm, but is not limited to this. The length of the width W is determined by the required moisture-proof performance, etc.

[0139] Increasing the width W can increase the creepage distance between the internal space 50 and the outside of the battery 2A via the joint surface of the joint 221. This can prevent foreign matter such as moisture from entering the internal space 50 and suppress deterioration of the power generating element 10. This can further improve the reliability of the battery 2A.

[0140] Furthermore, the joint 221 functions as a wall separating the internal space 50 from the outside of the battery 2A, thereby increasing the structural strength of the exterior film 220 in the portion facing the top surface of the power-generating element 10. This can improve the mechanical reliability of the battery 2A.

[0141] (Embodiment 3) Next, a third embodiment will be described.

[0142] The main difference between embodiment 3 and embodiment 2 is that one of the main surfaces of the two sealing parts is located within the internal space of the exterior film, similar to the joint part. The following description will focus on the differences from embodiment 2, and the description of the commonalities will be omitted or simplified.

[0143] Fig. 5A is a plan view of battery 3 according to this embodiment. Fig. 5B is a cross-sectional view of battery 3 taken along line VB-VB in Fig. 5A. The cross-sectional view of battery 3 taken along a cross-section parallel to the yz plane is the same as the cross-section of battery 2 shown in Fig. 3B. Alternatively, the cross-sectional view of battery 3 taken along a cross-section parallel to the yz plane may be the same as the cross-section of battery 2A shown in Fig. 4.

[0144] As shown in FIGS. 5A and 5B, battery 3 according to the present embodiment is different from battery 2 according to embodiment 2 in that it includes sealing part 323 instead of sealing part 223.

[0145] Sealing portion 323 is located at the tip end in the negative x-axis direction and is an example of a second bonding portion, which is a portion where parts of exterior film 220 overlap and bond together. Sealing portion 323 is formed by heat-sealing parts of the resin film of one film 225 together.

[0146] As shown in FIG. 5B , the sealing portion 323 is a portion where the end 225c and the end 225d of the film 225 are overlapped and joined. The sealing portion 323 has a main surface 323a and a main surface 323b opposite to the main surface 323a. The main surface 323a is located within the sealed internal space 50. The main surface 323a is an example of a third main surface and is part of the inner main surface of the exterior film 220. The main surface 323b is an example of a fourth main surface and is part of the outer main surface of the exterior film 220. In other words, the main surface 323b is located outside the internal space 50, not within the internal space 50.

[0147] Sealing portion 323 is formed by joining the outer main surface of end portion 225c and the inner main surface of end portion 225d of film 225. Specifically, sealing portion 323 is formed by forming film 225 into a bag shape and joining overlapping ends 225c and 225d so that ends 225c and 225d of one film 225 overlap. Sealing portion 323 is located at or near the bottom of bag-shaped exterior film 220.

[0148] The sealing portion 323 overlaps the power-generating element 10 in a plan view. Specifically, a main surface 323a of the sealing portion 323 is in contact with the bottom surface of the power-generating element 10. The sealing portion 323 may be provided on the top surface of the power-generating element 10. This increases the width of the sealing portion 323, thereby increasing the creepage distance between the internal space 50 and the outside of the battery 3 via the joint surface of the sealing portion 323. This prevents foreign matter such as moisture from entering the internal space 50, and suppresses deterioration of the power-generating element 10. This further improves the reliability of the battery 3.

[0149] According to the present embodiment, not only the main surface 221a (not shown) of the joint portion 221 but also the main surface 323a of the sealing portion 323 are located within the internal space 50. This allows the area efficiency of the battery 3 to be further improved.

[0150] <Modification> Fig. 6 is a cross-sectional view of a battery 3A according to a modification of the present embodiment. The cross section shown in Fig. 6 corresponds to the cross section taken along line VB-VB in Fig. 5A.

[0151] As shown in FIG. 6, the position of the sealing part 323 of the battery 3A is different from that of the battery 3. Specifically, the sealing part 323 faces the end face of the power-generating element 10. The width of the sealing part 323 is shorter than the thickness of the power-generating element 10. This makes it possible to reduce the thickness of the battery 3A. Note that in the cross section shown in FIG. 6, the width of the sealing part 323 is represented by the length of the sealing part 323 in the z-axis direction.

[0152] The sealing portion 323 may be in contact with the end face of the power generating element 10. This allows the internal space 50 to be smaller, further increasing the area efficiency of the battery 3A.

[0153] In the present embodiment and the modified example, an example has been shown in which exterior film 220 is formed using one film 225, but exterior film 220 may be formed using two films 25 and 26, as in embodiment 1. In this case, sealing portion 323 is formed by heat-sealing parts of the resin films of the two films 25 and 26 together.

[0154] (Fourth embodiment) Next, a fourth embodiment will be described.

[0155] The main difference between embodiment 4 and embodiment 3 is that the power generating element is a stack of multiple battery cells. The following description will focus on the differences with embodiment 3, and explanation of the commonalities will be omitted or simplified.

[0156] Fig. 7A is a plan view of the battery 4 according to this embodiment. Fig. 7B is a cross-sectional view of the battery 4 taken along line VIIB-VIIB in Fig. 7A. Fig. 7C is a side view of the battery 4 according to this embodiment.

[0157] 7A and 7B, battery 4 according to the present embodiment includes a power generating element 10A instead of power generating element 10, as compared to battery 3 according to embodiment 3. Battery 4 also includes a sealing part 423 instead of sealing part 323.

[0158] The power generating element 10A is a stack of multiple battery cells 100, as shown in FIG. 8A.

[0159] 8A is a cross-sectional view showing a power generating element 10A included in a battery 4 according to this embodiment. The power generating element 10A is a parallel-stacked power generating element in which a plurality of battery cells are electrically connected in parallel. As shown in FIG. 8A, the power generating element 10A includes two battery cells 100A and two battery cells 100B. The battery cells 100A and the battery cells 100B are stacked alternately one by one.

[0160] Both battery cells 100A and 100B are the smallest unit that functions as a battery and are also called unit cells. Battery cell 100B has a configuration in which battery cell 100A is turned upside down. Specifically, battery cell 100A includes an electrode current collector 140, an electrode active material layer 110, a solid electrolyte layer 130, a counter electrode active material layer 120, and a counter electrode current collector 150, which are layered in this order from the negative side to the positive side of the z axis. Battery cell 100B includes a counter electrode current collector 150, a counter electrode active material layer 120, a solid electrolyte layer 130, an electrode active material layer 110, and an electrode current collector 140, which are layered in this order from the negative side to the positive side of the z axis.

[0161] Adjacent battery cells 100A and 100B share one of the electrode current collector 140 and the counter electrode current collector 150. The current collector does not need to be shared, and the electrode current collectors 140 or counter electrode current collectors 150 of the battery cells 100A and 100B may be stacked together. The two stacked current collectors may be in direct contact with each other or may be joined via a conductive material, an adhesive material, or the like.

[0162] 7B, portions of the two counter electrode current collectors 150 extend outward from the main body of the power generating element 10A and are electrically connected to the extraction electrode 30. Although not shown, portions of the three electrode current collectors 140 extend outward from the main body of the power generating element 10A and are electrically connected to the extraction electrode 40. This electrically connects the two battery cells 100A and the two battery cells 100B in parallel. Note that there are no particular limitations on the connection between the extraction electrode and the current collectors and the parallel connection configuration.

[0163] The battery 4 may include a power generating element 10B shown in FIG. 8B instead of the power generating element 10A. FIG. 8B is a cross-sectional view showing the power generating element 10B included in the battery 4 according to this embodiment. The power generating element 10B is a series-stacked power generating element in which multiple battery cells are electrically connected in series. As shown in FIG. 8B, the power generating element 10B includes four battery cells 100C.

[0164] The four battery cells 100C are the smallest unit that functions as a battery and are also called unit cells. Each of the four battery cells 100C includes an electrode current collector 140, an electrode active material layer 110, a solid electrolyte layer 130, a counter electrode active material layer 120, and a counter electrode current collector 150, which are stacked in this order from the negative side to the positive side of the z axis.

[0165] Two adjacent battery cells 100C share one electrode current collector 140 and the other counter electrode current collector 150 as a single current collector. A shared current collector is also called a bipolar current collector. Note that the current collector does not need to be shared, and one electrode current collector 140 and the other counter electrode current collector 150 of two adjacent battery cells 100C may be stacked. The two stacked current collectors may be in direct contact or may be joined via a conductive material, an adhesive material, or the like.

[0166] The number of battery cells included in power generating elements 10A and 10B is not limited to four, and may be two, three, or five or more. Furthermore, battery 4 may include, as a power generating element, a stack of one or more parallel-stacked power generating elements and one or more series-stacked power generating elements.

[0167] As in the modified example of embodiment 3, sealing portion 423 faces the end face of power generating element 10A. In this embodiment, power generating element 10A includes multiple battery cells and is therefore thicker than power generating element 10. As a result, the area of the portion of exterior film 220 facing the end face of power generating element 10A, i.e., the area of the bottom surface of bag-shaped exterior film 220, is large. This allows the bonding area of film 225 at sealing portion 423 to be increased.

[0168] As shown in FIG. 7C , sealing portion 423 is a portion where end 225c, end 225d, end 225g, and end 225h of film 225 are overlapped and joined. End 225c is a portion folded in from the upper side (positive side of the z-axis) of film 225. End 225d is a portion folded in from the lower side (negative side of the z-axis) of film 225. End 225g is a portion folded in from the left side (negative side of the x-axis) of film 225. End 225h is a portion folded in from the right side (positive side of the x-axis) of film 225. The folding order is not particularly limited. Furthermore, end 225g and end 225h do not overlap, but this is not a limitation. That is, the four end portions 225c, 225d, 225g, and 225h of film 225 may be overlapped and joined to one another.

[0169] In this way, when the power generating element 10A or 10B placed in the internal space 50 is thick, by providing the sealing portion 423 at a portion facing the end face of the power generating element 10A or 10B, it is possible to prevent the sealing portion 423 and the power generating element 10A or 10B from overlapping in a plan view (when viewed from the positive side of the z-axis). This increases the area efficiency of the battery 4 and enables it to be made thinner.

[0170] (Other embodiments) Next, other embodiments will be described. The contents described below are applicable to the above-described embodiments and modifications.

[0171] <Extraction electrode> 9A and 9B are a plan view and a side view, respectively, of an extraction electrode 30 included in the batteries according to the embodiments and modifications. Note that the extraction electrode 40 has the same configuration as the extraction electrode 30, and therefore the extraction electrode 30 will be described below as a representative.

[0172] As shown in Figures 9A and 9B, the extraction electrode 30 includes a lead 31 and a resin part 32. The lead 31 is a conductive member and is connected to one of the positive and negative electrodes of the power generating element. The lead 31 is made of a metal material such as copper or aluminum. The shape of the lead 31 in a plan view is, but is not limited to, a rectangular shape that is elongated in one direction.

[0173] The resin portion 32 is provided in a ring shape so as to surround the surface of the lead 31. The resin portion 32 contains a thermoplastic resin as a main component. The resin portion 32 is formed using, for example, polypropylene, polyethylene, polycarbonate, polystyrene, polyvinyl chloride, ABS (Acrylonitrile Butadiene Styrene), or the like. The resin portion 32 is heat-sealed to the resin film of the laminate film when forming the sealing portion 24 or 224. This prevents gaps from occurring around the extraction electrode 30, and improves the sealing performance of the internal space 50.

[0174] <Example of combination of power generating element and internal space> Next, several examples of combinations of the power generating element 10 and the internal space 50 will be described with reference to FIGS. 10A to 10F.

[0175] 10A to 10F are diagrams showing examples of combinations of the shapes of the power generating element 10 and the internal space 50 according to each embodiment and each modification. In each diagram, the white arrow pointing toward the negative side of the x-axis indicates the insertion direction of the power generating element 10.

[0176] 10A shows an example in which the power generating element 10 has a rectangular shape in plan view and the internal space 50 has a trapezoidal shape in plan view, as described in each embodiment and each modified example. The inclination angles θ1 and θ2 of the tapered shape of the internal space 50 are each 0.25 degrees or more. This reduces the possibility of damage to the end portion when the power generating element 10 is inserted, thereby improving the reliability of the battery. The inclination angles θ1 and θ2 of the tapered shape of the internal space 50 may each be 0.5 degrees or more, 1 degree or more, or 2 degrees or more.

[0177] Furthermore, the gradient angles θ1 and θ2 of the tapered shape of the internal space 50 are each 10 degrees or less. This reduces the area within the internal space 50 where the power generating element 10 is not disposed, thereby improving the area efficiency of the battery. The gradient angles θ1 and θ2 of the tapered shape of the internal space 50 may each be 8 degrees or less, 5 degrees or less, or 3 degrees or less. The gradient angles θ1 and θ2 may be equal to each other or may be different.

[0178] 10B shows an example in which the power generating element 10 has a rectangular shape in plan view, and the internal space 50 has a quadrangle with one side of the rectangle tilted in plan view. FIG. 10B corresponds to an example in which the gradient angle θ2 shown in FIG. 10A is set to 0 degrees. The gradient angle θ1 is the same as in FIG. 10A.

[0179] 10C shows an example in which the power generating element 10 has a tapered shape in plan view and the internal space 50 has a rectangular shape in plan view. Specifically, the power generating element 10 has a trapezoidal shape in plan view. The power generating element 10 has an isosceles trapezoidal shape in plan view, with two sides parallel to the y-axis direction as upper and lower bases and two sides tilted with respect to the x-axis direction as legs.

[0180] The gradient angles θ3 and θ4 of the tapered shape of the power-generating element 10 are each 0.25 degrees or greater. This reduces the possibility of damage to the end portion when the power-generating element 10 is inserted, thereby improving the reliability of the battery. The gradient angles θ3 and θ4 of the tapered shape of the power-generating element 10 may each be 0.5 degrees or greater, 1 degree or greater, or 2 degrees or greater.

[0181] The gradient angles θ3 and θ4 of the tapered shape of the power-generating element 10 are each 10 degrees or less. This reduces the area in the internal space 50 where the power-generating element 10 is not disposed, thereby improving the area efficiency of the battery. The gradient angles θ3 and θ4 of the tapered shape of the power-generating element 10 may each be 8 degrees or less, 5 degrees or less, or 3 degrees or less. The gradient angles θ3 and θ4 may be equal to each other or may be different.

[0182] Fig. 10D shows an example in which the power generating element 10 has a quadrilateral shape in plan view with one side of a rectangle tilted, and the internal space 50 has a rectangular shape in plan view. Fig. 10D corresponds to an example in which the gradient angle θ4 shown in Fig. 10C is set to 0 degrees. The gradient angle θ3 is the same as in Fig. 10C.

[0183] Fig. 10E shows an example in which the power-generating element 10 and the internal space 50 each have a tapered shape in plan view. Specifically, in Fig. 10E, the power-generating element 10 and the internal space 50 each have a trapezoidal shape in plan view. Fig. 10E shows an example in which the internal space 50 in Fig. 10A is combined with the power-generating element 10 in Fig. 10C.

[0184] The gradient angles θ1, θ2, θ3, and θ4 are the same as those in FIGS. 10A and 10C. Note that gradient angle θ1 is equal to gradient angle θ3, and gradient angle θ2 is equal to gradient angle θ4. This allows the distance between the power generating element 10 and the side wall of the internal space 50 to be kept constant, further improving area efficiency. In other words, the loss of energy density of the battery can be sufficiently reduced. Note that gradient angle θ1 may be different from gradient angle θ3, and gradient angle θ2 may be different from gradient angle θ4.

[0185] Fig. 10F shows an example in which the power generating element 10 and the internal space 50 each have a quadrilateral shape in plan view, with one side of the rectangle tilted. Fig. 10F corresponds to an example in which the gradient angles θ2 and θ4 shown in Fig. 10E are each set to 0 degrees. The gradient angles θ1 and θ3 are the same as in Fig. 10E. Fig. 10F shows an example in which the internal space 50 of Fig. 10B is combined with the power generating element 10 of Fig. 10D.

[0186] Thus, the tapered shape of at least one of the power-generating element 10 and the internal space 50 is not particularly limited as long as it facilitates insertion of the power-generating element 10 into the internal space 50. The gradient may be provided on both sides of the insertion direction as shown in FIGS. 10A, 10C, and 10E, or on only one side of the insertion direction as shown in FIGS. 10B, 10D, and 10F. A shape with a gradient on both sides is known as a tapered shape. The taper may be a linear taper or a curved taper such as an exponential function or a parabola.

[0187] The gap between the exterior film 20 or 220 and the power-generating element 10 is designed to be as small as possible because it results in a loss of energy density relative to the volume of the battery. On the other hand, as the gap becomes smaller, the possibility of the inner surface of the exterior film 20 or 220 rubbing against the power-generating element 10, particularly the end face, and being damaged increases. For example, the minimum gap between the exterior film 20 or 220 and the power-generating element 10 is 0 mm or more and 2 mm or less. The minimum gap may be 0 mm or more and 1 mm or less, or 0 mm or more and 0.2 mm or less.

[0188] The minimum gap is formed at the leading end (negative side of the x-axis) of the insertion of the power generating element 10. After the minimum gap is formed, there is almost no friction between the exterior film 20 or 220 and the power generating element 10, further reducing the possibility of damage to the power generating element 10.

[0189] <Battery cell> Next, the specific configuration of the battery cell will be described.

[0190] 11A is a cross-sectional view showing a battery cell 100 included in the batteries according to the embodiments and modifications. As shown in FIG. 11A, the battery cell 100 includes an electrode active material layer 110, a counter electrode active material layer 120, a solid electrolyte layer 130, an electrode current collector 140, and a counter electrode current collector 150.

[0191] In this embodiment, the electrode active material layer 110 is, for example, a positive electrode active material layer, and the counter electrode active material layer 120 is, for example, a negative electrode active material layer. The electrode current collector 140 is, for example, a positive electrode current collector, and the counter electrode current collector 150 is, for example, a negative electrode current collector.

[0192] The electrode active material layer 110 includes, for example, a negative electrode active material as an electrode material. The electrode active material layer 110 is disposed opposite the counter electrode active material layer 120.

[0193] The negative electrode active material contained in the electrode active material layer 110 may be, for example, graphite, metallic lithium, or the like. As the negative electrode active material, various materials capable of extracting and inserting ions such as lithium (Li) or magnesium (Mg) may be used.

[0194] The material contained in the electrode active material layer 110 may be, for example, a solid electrolyte such as an inorganic solid electrolyte. Examples of inorganic solid electrolytes that can be used include sulfide solid electrolytes and oxide solid electrolytes. Examples of sulfide solid electrolytes that can be used include a mixture of lithium sulfide (LiS) and diphosphorus pentasulfide (P2S5). Examples of materials that can be used in the electrode active material layer 110 include a conductive material such as acetylene black, or a binder for bonding such as polyvinylidene fluoride.

[0195] The electrode active material layer 110 can be produced by applying a paste-like paint, in which the materials contained in the electrode active material layer 110 are kneaded together with a solvent, onto the surface of the electrode current collector 140 and drying the paint. In order to increase the density of the electrode active material layer 110, the electrode plate including the electrode active material layer 110 and the electrode current collector 140 may be pressed after drying. The thickness of the electrode active material layer 110 is, for example, 5 μm or more and 300 μm or less, but is not limited to this.

[0196] The counter electrode active material layer 120 is a layer containing, for example, a positive electrode material as an electrode material. The positive electrode material is a material that constitutes a counter electrode to the negative electrode material. The counter electrode active material layer 120 contains, for example, a positive electrode active material.

[0197] Examples of the positive electrode active material contained in the counter electrode active material layer 120 that can be used include lithium cobalt oxide composite oxide (LCO), lithium nickel oxide composite oxide (LNO), lithium manganese oxide composite oxide (LMO), lithium-manganese-nickel composite oxide (LMNO), lithium-manganese-cobalt composite oxide (LMCO), lithium-nickel-cobalt composite oxide (LNCO), and lithium-nickel-manganese-cobalt composite oxide (LNMCO).

[0198] As the positive electrode active material, various materials that can extract and insert ions such as Li or Mg can be used.

[0199] The counter electrode active material layer 120 may contain, for example, a solid electrolyte such as an inorganic solid electrolyte. Examples of inorganic solid electrolytes include sulfide solid electrolytes and oxide solid electrolytes. Examples of sulfide solid electrolytes include a mixture of Li2S and P2S5. The surface of the positive electrode active material may be coated with a solid electrolyte. Examples of materials that may be used in the counter electrode active material layer 120 include a conductive material such as acetylene black, or a binder such as polyvinylidene fluoride.

[0200] The counter electrode active material layer 120 can be produced by applying a paste-like paint, in which the materials contained in the counter electrode active material layer 120 are kneaded together with a solvent, onto the surface of the counter electrode current collector 150 and drying the paint. In order to increase the density of the counter electrode active material layer 120, the positive electrode plate including the counter electrode active material layer 120 and the counter electrode current collector 150 may be pressed after drying. The thickness of the counter electrode active material layer 120 is, for example, not less than 5 μm and not more than 300 μm, but is not limited to this.

[0201] The solid electrolyte layer 130 is located between the electrode active material layer 110 and the counter electrode active material layer 120. The solid electrolyte layer 130 is in contact with both the electrode active material layer 110 and the counter electrode active material layer 120. The solid electrolyte layer 130 is a layer containing an electrolyte material. As the electrolyte material, a generally known electrolyte for batteries can be used. The thickness of the solid electrolyte layer 130 may be 5 μm or more and 300 μm or less, or 5 μm or more and 100 μm or less.

[0202] The solid electrolyte may be, for example, an inorganic solid electrolyte. The inorganic solid electrolyte may be, for example, a sulfide solid electrolyte or an oxide solid electrolyte. The sulfide solid electrolyte may be, for example, a mixture of Li2S and P2S5. The solid electrolyte layer 130 may contain, in addition to the electrolyte material, a binder such as polyvinylidene fluoride.

[0203] In each embodiment and each modified example, the electrode active material layer 110, the counter electrode active material layer 120, and the solid electrolyte layer 130 are maintained in the shape of parallel plates. This makes it possible to prevent cracking or collapse due to bending. The electrode active material layer 110, the counter electrode active material layer 120, and the solid electrolyte layer 130 may be smoothly curved together.

[0204] The electrode current collector 140 and the counter electrode current collector 150 are each a conductive foil-like, plate-like, or mesh-like member. The electrode current collector 140 and the counter electrode current collector 150 may each be, for example, a conductive thin film. The electrode current collector 140 and the counter electrode current collector 150 may be made of a material such as stainless steel (SUS), aluminum (Al), copper (Cu), or nickel (Ni). The electrode current collector 140 and the counter electrode current collector 150 may be made of different materials.

[0205] The thickness of each of the electrode current collector 140 and the counter electrode current collector 150 is, for example, not less than 5 μm and not more than 100 μm, but is not limited to this.

[0206] An electrode active material layer 110 is provided on the main surface of the electrode current collector 140. The electrode active material layer 110 may be provided in contact with the main surface of the electrode current collector 140, or may be provided via another layer, such as a bonding layer or current collector layer, containing a conductive material.

[0207] A counter electrode active material layer 120 is provided on the main surface of the counter electrode current collector 150. The counter electrode active material layer 120 may be provided in contact with the main surface of the counter electrode current collector 150, or may be provided via another layer, such as a bonding layer or a current collector layer, containing a conductive material.

[0208] The battery cell 100 does not necessarily have to include the electrode current collector 140 and the counter electrode current collector 150. Figures 11B and 11C are cross-sectional views showing other examples of battery cells included in the batteries according to the embodiments and modifications.

[0209] The battery cell 100D shown in Fig. 11B is a battery cell that does not include a counter electrode current collector 150. The battery cell 100E shown in Fig. 11C is a battery cell that does not include an electrode current collector 140. For example, by stacking at least two or more of the battery cells 100, 100D, and 100E, the power generating element 10A shown in Fig. 8A and the power generating element 10B shown in Fig. 8B can be easily formed.

[0210] <Manufacturing method> Next, a method for manufacturing the battery according to each embodiment and each modification will be described.

[0211] FIG. 12 is a flowchart showing a method for manufacturing a battery according to each embodiment and each modification.

[0212] As shown in Fig. 12, first, a power generating element is prepared (S10). Next, a cylindrical exterior film is prepared (S20). Next, the power generating element is inserted into the internal space of the exterior film (S30). Next, the insertion opening of the internal space is fused to seal the internal space (S40).

[0213] The specific processing of each step will be described below. Note that the manufacturing method shown in FIG. 12 is merely an example. For example, the order of performing each step shown in FIG. 12 may be changed. For example, the step of preparing the power generating element (S10) may be performed after the step of preparing the exterior film (S20). Alternatively, the step of preparing the power generating element (S10) may be performed simultaneously with the step of preparing the exterior film (S20).

[0214] First, the step of preparing a power generating element (S10) will be described. The power generating element prepared in this step is, for example, the power generating element 10 shown in Figures 1B and 1C.

[0215] First, for example, a paste-like paint prepared by kneading the materials contained in the electrode active material layer 110 together with a solvent is applied to the main surface of the electrode current collector 140 and dried to form the electrode active material layer 110. In order to increase the density of the electrode active material layer 110, the electrode active material layer 110 applied to the electrode current collector 140 may be pressed after drying.

[0216] Next, for example, a paste-like paint obtained by kneading the materials contained in the counter electrode active material layer 120 together with a solvent is applied to the main surface of the counter electrode current collector 150 and dried to form the counter electrode active material layer 120. In order to increase the density of the counter electrode active material layer 120, the counter electrode active material layer 120 applied to the counter electrode current collector 150 may be pressed after drying. Note that the formation of the electrode active material layer 110 and the formation of the counter electrode active material layer 120 may be performed either first, or may be performed simultaneously in parallel.

[0217] Next, for example, a paste-like paint prepared by kneading the materials contained in the solid electrolyte layer 130 together with a solvent is applied to the main surfaces of the electrode active material layer 110 and / or the counter electrode active material layer 120 and dried to form the solid electrolyte layer 130 or a portion thereof. Alternatively, the solid electrolyte layer 130 may be formed by applying the paste-like paint to a release film and drying it.

[0218] Next, for example, the electrode current collector 140, the electrode active material layer 110, the solid electrolyte layer 130, the counter electrode active material layer 120, and the counter electrode current collector 150 are stacked in this order and pressed together to form the battery cell 100 as the power generating element 10. Pressing methods that can be used include, for example, plate pressing, roll pressing, and isostatic pressing. Furthermore, to improve the adhesion and density of each layer, heating may be applied during pressing. The heating temperature may be set within a range that does not cause chemical changes in the materials of each layer due to heat, for example, 60°C or higher and 200°C or lower.

[0219] When preparing the power generating element 10A shown in FIG. 8A or the power generating element 10B shown in FIG. 8B as a power generating element, the battery cells 100 manufactured through the above steps are stacked. Alternatively, the battery cells 100D or 100E manufactured by a similar manufacturing method may be stacked. When stacking, for example, the multiple battery cells 100 may be integrated by bonding them with an adhesive. Alternatively, the multiple battery cells 100 may be integrated by stacking all of the above components and applying pressure to bond them together. The edges of the integrated battery cells 100, electrode current collector 140, and counter electrode current collector 150 do not need to be flush with each other, and a step may be provided for each battery cell 100.

[0220] The above steps are used to manufacture the power generating element 10, 10A, or 10B. A protective layer 60 shown in Fig. 2D may be formed on the end surface of the power generating element 10, 10A, or 10B.

[0221] Next, the step (S20) of preparing a cylindrical exterior film will be described. First, a case where exterior film 20 is formed using two films 25 and 26 will be described with reference to FIG. 13A. FIG. 13A is a flowchart showing an example of the preparation step of exterior film 20 in the manufacturing method of a battery according to each embodiment and each modified example. Below, an example of forming exterior film 20 shown in FIG. 1B and FIG. 1C will be described, but the same applies to the exterior film 20 shown in FIG. 2A to FIG. 2C.

[0222] First, two films 25 and 26 are prepared (S21). Next, with film 25 and film 26 stacked, two overlapping portions of films 25 and 26 are joined together to form joints 21 and 22 (S23). The two overlapping portions are an example of a first overlapping portion and a second overlapping portion, and are, for example, portions along two opposing sides when each of films 25 and 26 has a rectangular shape in plan view. The ends of films 25 and 26 are folded inward and heat-sealed to form joints 21 and 22 that protrude inward. Furthermore, joints 21 and 22 may be heat-sealed to the inner surface of film 25 or 26, respectively.

[0223] Next, one of the openings of the cylindrical exterior film 20 is joined (S25). Specifically, end 25c of film 25 and end 26c of film 26 are joined by heat sealing to form sealing portion 23. Note that, as in the third and fourth embodiments, sealing portion 323 or 423 may be formed whose main surface is located within internal space 50. Specifically, end 25c of film 25 and end 26c of film 26 may each be folded inward and joined. Furthermore, at this time, end 25c of film 25 and end 26c of film 26 may be joined by overlapping them so as to form a wall that separates internal space 50 from the outside of exterior film 20.

[0224] The above steps can be used to form the exterior film 20. Note that the cylindrical exterior film 20 may be formed by joining three or more films together.

[0225] Next, a case where the exterior film 220 is formed using one film will be described with reference to Fig. 13B. Fig. 13B is a flowchart showing another example of the preparation step for the exterior film 220 in the manufacturing method for the battery according to each embodiment and each modified example. Below, an example of forming the exterior film 220 shown in Fig. 6 will be described, but the same applies to the exterior films 220 shown in Figs. 3B, 4, 5B, and 7B.

[0226] First, one sheet of film 225 is prepared (S22). Next, one sheet of film 225 is formed into a cylindrical shape so that portions of the sheet of film 225 overlap, and the overlapped portions are joined (S24). The overlapped portions are portions where the inner main surface and the outer main surface of film 225 come into contact, but are not limited to this. The overlapped portions may also be portions where the film 225 is folded inward so that the outer main surfaces come into contact. The overlapped portions are heat-sealed to form joint portion 221.

[0227] Next, one of the openings of the cylindrical exterior film 220 is folded inward and joined (S26). Specifically, ends 225c and 225d of film 225 are joined by heat sealing to form sealing portion 323. More specifically, ends 225c and 225d of film 225 may be joined by overlapping them so as to form a wall that separates internal space 50 from the outside of exterior film 220.

[0228] Through the above steps, the exterior film 220 can be formed.

[0229] Next, the step of inserting the power generating element (S30) will be described.

[0230] When inserting the power generating element 10 into the internal space 50, the insertion direction is the tip direction of the tapered shape of either the power generating element 10 or the internal space 50. This makes it difficult for the power generating element 10 to come into contact with the inner surface of the exterior film 20, thereby suppressing damage to the end face of the power generating element 10.

[0231] Before insertion, the extraction electrodes 30 and 40 are connected to the power generating element 10. This allows the extraction electrodes 30 and 40 to be connected with high precision without being affected by the exterior film 20. Note that the extraction electrodes 30 and 40 may be connected during or after insertion.

[0232] Next, the step (S40) of fusing the insertion opening will be described.

[0233] After inserting the power generating element 10 into the internal space 50, the rear end of the exterior film 20 or 220 in the insertion direction is sealed by sandwiching the lead 31 connected to the power generating element 10. Specifically, the resin part 32 provided around the lead 31 is sandwiched between the exterior film 20 or 220 and fused to form the sealing part 24 or 224. This seals the internal space 50.

[0234] At this time, the internal space 50 is sealed in a reduced pressure atmosphere lower than atmospheric pressure. The reduced pressure atmosphere is, for example, a vacuum state, but is not particularly limited as long as it is lower than atmospheric pressure. This allows the exterior film 20 or 220 and the power generating element 10 to be tightly attached at atmospheric pressure after sealing, thereby improving the volumetric efficiency of the battery. Furthermore, the amount of gases such as oxygen enclosed in the internal space 50 can be reduced, thereby suppressing deterioration of the power generating element 10. Furthermore, improved adhesion between the exterior film 20 or 220 and the power generating element 10 restricts movement of the power generating element 10 within the exterior film 20 or 220. This prevents damage to the power generating element 10. This, in turn, improves the reliability of the battery. Furthermore, wrinkles and sagging are less likely to occur on the outer surface of the exterior film 20 or 220, improving the appearance of the battery.

[0235] (Other embodiments) While the batteries and battery manufacturing methods according to one or more aspects have been described based on the embodiments, the present disclosure is not limited to these embodiments. As long as they do not deviate from the gist of the present disclosure, various modifications conceivable by those skilled in the art to the present embodiments and configurations constructed by combining components of different embodiments are also included within the scope of the present disclosure.

[0236] In each embodiment, an example has been shown in which the gradient of the power-generating element or the sealed space is formed in a straight line, but this is not limited thereto. The gradient may be a curve. The curve may be either downwardly convex or upwardly convex. The gradient may also be stepped. In other words, the width does not need to narrow all the way from end to end, and the width may narrow smoothly or in steps.

[0237] In each embodiment, the planar shape of the exterior film and the planar shape of the sealed space are substantially the same, but this is not limited to this. For example, if the sealed space has a tapered shape, the planar shape of the exterior film may be rectangular or square. Furthermore, the first bonding portion does not need to be formed in a linear shape with a predetermined width, and may be formed, for example, so that the planar shape is a right triangle or a rectangle with one side slanted.

[0238] For example, although the battery is an all-solid-state battery in the above example, the present invention is not limited to this. The power generating element may contain an electrolyte solution.

[0239] Furthermore, various modifications, substitutions, additions, omissions, etc. can be made to each of the above-described embodiments within the scope of the claims or their equivalents. [Industrial Applicability]

[0240] The present disclosure can be widely used in batteries for electronic devices, electrical appliances, electric vehicles, and the like. [Explanation of symbols]

[0241] 1, 1A, 1B, 1C, 1D, 2, 2A, 3, 3A, 4 batteries 10, 10A, 10B power generation elements 20, 220 exterior film 21, 21A, 21B, 21C, 22, 22A, 22B, 22C, 221 joint 21a, 21b, 221a, 221b, 323a, 323b main surface 23, 24, 223, 224, 323, 423 Sealing part 25, 26, 225 film 25a, 25b, 25c, 25d, 26a, 26b, 26c, 26d, 225a, 225b, 225c, 225d, 225e, 225f, 225g, 225h End 30, 40 Extraction electrode 31 Lead 32 Resin part 50 Interior Space 60 protective layer 100, 100A, 100B, 100C, 100D, 100E battery cells 110 Electrode active material layer 120 Counter electrode active material layer 130 Solid electrolyte layer 140 Electrode current collector 150 Counter electrode current collector

Claims

1. an exterior film having a sealed space; a power generating element disposed in the sealed space; Equipped with the exterior film has a first bonding portion where parts of the exterior film are overlapped and bonded to each other, the first bonding portion has a first main surface located within the sealed space, At least one of the power-generating element and the sealed space has a tapered shape in which the width in a first direction perpendicular to the stacking direction of the power-generating element becomes narrower along a second direction perpendicular to the first direction and the stacking direction. battery.

2. the first bonding portion has a second main surface opposite to the first main surface, The second main surface is located on the outside of the exterior film. The battery of claim 1 .

3. the first bonding portion has a second main surface opposite to the first main surface, The second main surface is located within the sealed space. The battery of claim 1 .

4. the first bonding portion has a second main surface opposite to the first main surface, The second main surface is joined to a part of the exterior film other than the first joining portion. The battery of claim 1 .

5. The power generating element has a rectangular shape in plan view. The battery according to any one of claims 1 to 4.

6. The power generating element has a trapezoidal shape in a plan view. The battery of claim 5.

7. The width of the first joint is 3 mm or more. The battery according to any one of claims 1 to 4.

8. The tapered shape has a slope angle of 0.25 degrees or more. The battery according to any one of claims 1 to 4.

9. The tapered shape has a slope angle of 10 degrees or less. The battery according to any one of claims 1 to 4.

10. When viewed from above, the power generating element and the first joint portion overlap each other. The battery according to any one of claims 1 to 4.

11. the exterior film has a second joint portion located at a tip end in the second direction, the second joint portion being a portion where parts of the exterior film are overlapped and joined together, the second bonding portion has a third main surface located within the sealed space; The battery according to any one of claims 1 to 4.

12. the second bonding portion has a fourth main surface opposite to the third main surface, The fourth main surface is located on the outside of the exterior film. The battery of claim 11.

13. When viewed from above, the power-generating element and the second joint portion overlap each other. The battery of claim 11.

14. A step of preparing a cylindrical exterior film having a joint portion where parts of the exterior film are overlapped and joined together; and inserting a power generating element into the internal space of the exterior film, the joint portion has a main surface located within the internal space, At least one of the power-generating element and the internal space has a tapered shape in which the width in a first direction perpendicular to the stacking direction of the power-generating element becomes narrower along a second direction perpendicular to the first direction and the stacking direction. How batteries are manufactured.

15. The preparing step includes a step of forming the joint by bonding a first overlapping portion and a second overlapping portion of the first film and the second film in a state where the first film and the second film are overlapped with each other. The method for manufacturing the battery according to claim 14.

16. The preparing step includes a step of forming the single film into a cylindrical shape so that parts of the single film overlap each other, and joining the overlapped parts to form the joint portion. The method for manufacturing the battery according to claim 14.

17. Before the inserting step, a step of folding and joining parts of the exterior film to each other at the tip end in the second direction toward the internal space, A method for manufacturing the battery according to any one of claims 14 to 16.

18. Before the inserting step, a step of overlapping and joining parts of the exterior film to each other at the leading end in the second direction so as to form a wall separating the internal space from the outside of the exterior film is included. A method for manufacturing the battery according to any one of claims 14 to 16.

19. after the inserting step, a step of sealing the rear end portion of the exterior film in the second direction by sandwiching a lead connected to the power-generating element, A method for manufacturing the battery according to any one of claims 14 to 16.

20. After the inserting step, a step of sealing the internal space in a reduced pressure atmosphere lower than atmospheric pressure is included. A method for manufacturing the battery according to any one of claims 14 to 16.

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