Battery

Abstract

To provide a battery with high productivity and high volume energy density.SOLUTION: A battery 1 includes: an electrode current collector 50; a power generation element 70 including a structure in which an electrode layer 40, a solid electrolyte layer 30, and a counter electrode layer 20 are stacked in this order from the electrode current collector 50 side on the electrode current collector 50; and a counter electrode current collector 10 including a tilt structure part 10a that is stacked on the counter electrode layer 20 in the power generation element 70. The power generation element 70 includes a first main surface 70b located on the electrode current collector 50 side, and a second main surface 70c facing back-to-back the first main surface 70b and tilting with respect to the first main surface 70b. A thickness of the tilt structure part 10a increases toward a direction where a thickness of the power generation element 70 decreases due to the tilt of the second main surface 70c to the first main surface 70b.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to batteries. [Background technology]

[0002] Patent Documents 1 and 2 disclose configurations relating to stacked cells of all-solid-state batteries. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-243395 [Patent Document 2] International Publication No. 2020 / 145177 Summary of the Invention [Problem to be solved by the invention]

[0004] In the prior art, there is a demand for a battery that has both high volumetric energy density and high productivity. Therefore, an object of the present disclosure is to provide a battery that has high productivity and high volumetric energy density. [Means for solving the problem]

[0005] A battery according to one embodiment of the present disclosure comprises an electrode current collector, a power generating element having a structure in which an electrode layer, a solid electrolyte layer, and a counter electrode layer are stacked on the electrode current collector in this order from the electrode current collector side, and an inclined current collector having an inclined structure portion stacked on the counter electrode layer of the power generating element, wherein the power generating element has a first main surface located on the electrode current collector side and a second main surface facing away from the first main surface and inclined with respect to the first main surface, and the thickness of the inclined structure portion increases as the thickness of the power generating element decreases due to the inclination of the second main surface with respect to the first main surface. [Effects of the Invention]

[0006] According to the present disclosure, the productivity and volumetric energy density of batteries can be increased. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view of a battery according to a first embodiment. [Figure 2] FIG. 2 is a cross-sectional view of the battery according to the first embodiment. [Figure 3] FIG. 3 is another cross-sectional view of the battery according to embodiment 1. In FIG. [Figure 4A] FIG. 4A is a cross-sectional view of a counter electrode current collector according to Embodiment 1. FIG. [Figure 4B] FIG. 4B is a cross-sectional view of another example of the counter electrode current collector according to the first embodiment. [Figure 4C] FIG. 4C is a cross-sectional view of another example of the counter electrode current collector according to the first embodiment. [Figure 4D] FIG. 4D is a cross-sectional view of another example of the counter electrode current collector according to the first embodiment. [Figure 4E] FIG. 4E is a cross-sectional view of another example of the counter electrode current collector according to the first embodiment. [Figure 4F] FIG. 4F is a cross-sectional view of another example of the counter electrode current collector according to the first embodiment. [Figure 5] FIG. 5 is a flowchart showing an example of a method for manufacturing the battery according to the first embodiment. [Figure 6] FIG. 6 is a perspective view of the cell stack current collector according to the first embodiment. [Figure 7] FIG. 7 is a cross-sectional view of the cell current collector stack according to the first embodiment. [Figure 8] FIG. 8 is another cross-sectional view of the cell current collector stack according to the first embodiment. [Figure 9] FIG. 9 is a cross-sectional view illustrating a power generating element having a uniform thickness. [Figure 10] FIG. 10 is a cross-sectional view illustrating the power generating element according to the first embodiment. [Figure 11] FIG. 11 is a cross-sectional view showing a state in which the current collector stack according to the first embodiment is folded back in a zigzag manner. [Figure 12] FIG. 12 is a cross-sectional view of a battery according to a comparative example. [Figure 13] FIG. 13 is a cross-sectional view of the battery according to the second embodiment. [Figure 14] FIG. 14 is a cross-sectional view of the battery according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] (How one aspect of the present disclosure was achieved) In the manufacture of batteries, various methods can be used for the process of forming a power generating element in which an anode layer, a solid electrolyte layer, and a cathode layer are laminated. From the viewpoint of productivity, a process is known in which a slurry in which materials for each layer are dispersed in a solvent is applied to a current collector by a coating method such as a die coating method, and the solvent is dried to form a power generating element. Furthermore, by applying a layer coating method in which the anode layer, the solid electrolyte layer, and the cathode layer are applied in a layered manner in the layering direction, productivity can be improved compared to a process in which each layer is formed individually and then laminated by transferring, such as a transfer method.

[0009] When applying a slurry using die coating, the thickness is highly uniform in the flow direction. However, thickness may vary across the width of the coating (the direction in which the die outlet for die coating extends). The thickness distribution varies depending on the design, but is typically at most 10%, more preferably at most 5%. This means, for example, that if the thickness at one end of the width of the coating is 50 μm, the thickness at the other end is at least 45 μm, more preferably at least 47.5 μm.

[0010] Furthermore, if the thickness of the negative electrode layer is distributed in the coating width direction, the capacity of the negative electrode layer will change in the coating width direction. Therefore, from the viewpoint of battery reliability, it is preferable that the positive electrode layer also has a thickness distribution similar to that of the negative electrode layer so that the capacity ratio of the positive and negative electrodes in the coating width direction is constant. Therefore, when the layers are coated in layers, the thickness distribution accumulates in the coating width direction, and the entire power generating element becomes thicker on the side with a thicker negative electrode layer and thinner on the side with a thinner negative electrode layer. If the power generating element has such a thickness distribution, wasted space is likely to be generated when packaging the battery, and the volumetric energy density decreases.

[0011] On the other hand, adjusting the coating conditions may be considered to eliminate thickness variations among the layers of the power generating element, but achieving a uniform thickness across the coating width is difficult and requires a lot of time for adjustments, etc., which reduces battery productivity.

[0012] Furthermore, to operate a device using a battery, it is necessary to ensure the voltage and capacity required for operation. While unit batteries with a certain voltage and capacity can be combined in series or parallel for use, creating a battery pack increases the pack volume, which can be a factor in reducing the volumetric energy density. For this reason, it is useful to increase the capacity of the unit batteries in advance. The capacity of a unit battery can be increased, for example, by increasing the battery reaction area. Known manufacturing methods for increasing battery capacity include the fighting method and the stacking method.

[0013] While the fighting method can increase the volumetric energy density, the bending stress applied to the battery's power generating elements during fighting can cause layers containing active materials to peel off from the current collector, reducing battery performance and reliability. The stacking method involves stacking multiple individual power generating elements in the stacking direction, and while this method is suitable for increasing capacity, there is room for improvement in productivity.

[0014] For example, in the lamination method, it is conceivable to form multiple power generating elements in a continuous process in order to efficiently form power generating elements and improve productivity. In this case, if the power generating elements are layered and coated in the same flow direction, the thickness distribution of the formed power generating elements will be smaller on the same side. If such power generating elements are simply layered, the thickness distribution of the power generating elements will accumulate, resulting in a larger thickness distribution for the entire battery. This makes it even more likely that wasted space will be generated when packaging the battery, for example.

[0015] The present disclosure has been made in view of the above-mentioned problems, and provides a battery manufacturing method and a battery having high productivity and volumetric energy density.

[0016] (Summary of the Disclosure) Below are several examples of batteries according to the present disclosure.

[0017] <1> an electrode current collector; a power generating element having a structure in which an electrode layer, a solid electrolyte layer, and a counter electrode layer are laminated in this order from the electrode current collector side on the electrode current collector; a gradient current collector having a gradient structure portion laminated on the counter electrode layer of the power generating element, the power-generating element has a first main surface located on the electrode current collector side and a second main surface facing away from the first main surface and inclined relative to the first main surface, the thickness of the inclined structure portion increases as the thickness of the power generating element decreases due to the inclination of the second main surface relative to the first main surface. battery.

[0018] As a result, even when forming the power generating element while allowing for some thickness variation to improve productivity, a sloped structure portion that increases in thickness as the power generating element decreases in thickness is laminated on the power generating element, thereby mitigating the effect of the thickness variation of the power generating element and reducing the thickness variation for the entire battery. This reduces distortion of the battery shape and reduces the formation of wasted space when packaging the battery, thereby improving the productivity and volumetric energy density of the battery.

[0019] <2> The difference between the maximum thickness and the minimum thickness of the inclined structure portion is 15 μm or less. <1> The battery described in

[0020] This reduces the thickness distribution in the inclined structure portion, making it possible to easily form an inclined current collector.

[0021] <3> The ratio of the maximum thickness to the minimum thickness of the gradient structure portion is 3.5 or less. <1> or <2> The battery described in

[0022] This reduces the thickness distribution in the inclined structure portion, making it possible to easily form an inclined current collector.

[0023] <4> The gradient current collector is made of a metal foil. <1> from <3> 1. A battery according to any one of the preceding claims.

[0024] This simplifies the structure of the gradient current collector.

[0025] <5> The gradient current collector includes a metal foil and a conductive resin layer laminated on the metal foil. <1> from <3> 1. A battery according to any one of the preceding claims.

[0026] This allows the conductive resin layer to be produced by coating or the like, making it easy to adjust the thickness distribution and to form a gradient current collector having a gradient structure portion.

[0027] <6> The gradient current collector includes a support member having a thickness distribution and a metal foil covering the support member. <1> from <3> 1. A battery according to any one of the preceding claims.

[0028] This allows the material of the support member to be selected regardless of the electrical connection with the counter electrode layer of the power generating element, making it possible to select a material that can be easily processed into the desired shape of the support member, making it easier to form a gradient collector having a gradient structure portion.

[0029] <7> The gradient current collector further includes a conductive resin layer covering the metal foil. <6> The battery described in

[0030] This makes it possible to easily adjust the thickness and thickness distribution of the gradient structure portion by adjusting the thickness and thickness distribution of the conductive resin layer.

[0031] <8> A plurality of the power generating elements stacked together; a plurality of counter electrode current collectors, at least one of which is the gradient current collector, stacked on the counter electrode layer; the electrode current collector has a plurality of electrode current collecting portions arranged along the stacking direction, and a folded portion that connects adjacent electrode current collecting portions among the plurality of electrode current collecting portions and is folded back in a first direction, the power generating element is laminated on both surfaces of each of the plurality of electrode current collecting portions, the plurality of counter electrode current collectors are arranged to sandwich the plurality of electrode current collectors, respectively, via the power generating elements stacked on both surfaces of the electrode current collectors. <1> from <7> 10. The battery according to claim 1 ,

[0032] This allows the electrode current collector, on both sides of which the power generating element is formed, to be folded back and the power generating element to be stacked, thereby reducing the number of steps compared to using individualized electrode current collectors and stacking them together with the power generating element, and further improving battery productivity.

[0033] <9> In each of the plurality of power generating elements, the direction in which the thickness of the power generating element is reduced due to the inclination of the second main surface with respect to the first main surface is the same as each other. <8> The battery described in

[0034] As a result, even if the power generating elements are efficiently formed, for example, by a continuous process, and the thickness of each of the power generating elements decreases in the same direction, resulting in a cumulative thickness distribution of the power generating elements, the gradient current collector can mitigate the influence of the cumulative thickness distribution of the power generating elements on the entire battery, thereby reducing the thickness distribution, thereby improving productivity and volumetric energy density.

[0035] <10> Each of the plurality of counter electrode current collectors is the inclined current collector. <9> The battery described in

[0036] This allows each of the plurality of counter electrode current collectors to mitigate the influence of the cumulative thickness distribution of the power generating elements on the entire battery, thereby making it possible to reduce the thickness distribution.

[0037] <11> the plurality of counter electrode current collectors include, as the inclined current collectors, a first inclined current collector positioned between the power-generating elements stacked on adjacent electrode current collectors among the plurality of electrode current collectors and facing each other, and a second inclined current collector positioned at an end of the battery in the stacking direction, a difference between the maximum thickness and the minimum thickness of the inclined structure portion of the second inclined current collector is smaller than a difference between the maximum thickness and the minimum thickness of the inclined structure portion of the first inclined current collector; <10> The battery described in

[0038] This makes the difference between the maximum and minimum thicknesses of the inclined structure of the second inclined current collector, which is located at the end and on which one power generating element is stacked, smaller than the inclined structure of the first inclined current collector sandwiched between two power generating elements. As a result, the thickness distribution of the inclined current collectors can be adjusted according to the number of power generating elements to be stacked, making it possible to make the top and bottom surfaces of the battery closer to parallel.

[0039] <12> the battery further includes a connection member that covers an end surface of each of the plurality of power generating elements in a second direction intersecting with the first direction and is connected to one end of each of the plurality of counter electrode current collectors. <8> from <11> 1. A battery according to any one of the preceding claims.

[0040] This allows the multiple counter electrode current collectors to be connected to each other, and therefore allows the multiple counter electrode current collectors to be arranged so as to be stacked on the counter electrode layers of the multiple power generating elements, for example, by inserting the multiple counter electrode current collectors collectively between the multiple power generating elements, thereby improving the productivity of the battery.

[0041] <13> The plurality of power generating elements include a first power generating element and a second power generating element whose thicknesses decrease in different directions due to the second main surface being inclined with respect to the first main surface. <8> The battery described in

[0042] This makes it difficult for variations in thickness of the power generating elements to accumulate even when multiple power generating elements are stacked, thereby reducing the thickness variation of the entire battery.

[0043] <14> In each of the plurality of power-generating elements, a direction in which the thickness of the power-generating element is reduced due to the inclination of the second main surface with respect to the first main surface intersects with the first direction. <8> from <13> 1. A battery according to any one of the preceding claims.

[0044] This allows the power generating element to be formed on the electrode current collector in a continuous process with the first direction as the flow direction when the power generating element is formed using a coating process such as die coating in which the thickness is distributed in a direction intersecting the flow direction.

[0045] <15> The electrode layer is a negative electrode layer. The counter electrode layer is a positive electrode layer. <1> from <14> 1. A battery according to any one of the preceding claims.

[0046] For example, when forming a power generating element, by forming the electrode layer on the electrode current collector side larger than the counter electrode layer, the power generating element can be formed even if the alignment accuracy of each layer is low, making it easy to increase productivity. In this case, if the electrode layer formed larger is the negative electrode layer and the counter electrode layer is the positive electrode layer, the negative electrode layer can easily accept ions from the positive electrode layer, thereby suppressing metal deposition. Therefore, reliability can be improved even when productivity is increased by forming the electrode layer larger than the counter electrode layer.

[0047] Hereinafter, the embodiments will be specifically described with reference to the drawings.

[0048] The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection configurations, steps, and step order 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 the independent claims are described as optional components.

[0049] 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.

[0050] Furthermore, in this specification, terms indicating the relationship between elements, such as parallel or orthogonal, terms indicating the shape of elements, such as rectangular or rectangular parallelepiped, and numerical ranges are not expressions that only express a strict meaning, but are expressions that also include a substantially equivalent range, for example, a difference of about a few percent.

[0051] In this specification and drawings, the x-axis, y-axis, and z-axis refer to the three axes of a three-dimensional Cartesian coordinate system. When the shape of the power generating element of a battery in a plan view is rectangular, the x-axis and y-axis correspond to directions parallel to a first side of the rectangle and a second side perpendicular to the first side, respectively. The z-axis corresponds to, for example, the stacking direction of the multiple power generating elements included in the battery. In this specification, the x-axis direction is an example of a first direction, and the y-axis direction is an example of a second direction.

[0052] In this specification, the term "stacking direction" refers to the direction in which multiple power generating elements are stacked and arranged. In this specification, the term "plan view" refers to a view perpendicular to the main surface (e.g., the first main surface) of the power generating element, unless otherwise specified, such as when used alone. When the term "plan view of a certain surface" is used, such as "plan view of a side surface," it refers to a view of the "certain surface" from the front.

[0053] Furthermore, in this specification, the terms "upper" and "lower" do not refer to the upward direction (vertically upward) and downward direction (vertically downward) in absolute spatial recognition, but are used as terms defined by a relative positional relationship based on the stacking order in a stacked configuration. Furthermore, the terms "upper" and "lower" are used not only when two components are arranged with a gap between them and another component is present between them, but also when two components are arranged closely together and are in contact with each other. In the following description, the negative side of the z axis is referred to as "lower" or "lower side," and the positive side of the z axis is referred to as "upper" or "upper side."

[0054] In this specification, the expression "covering A" means covering at least a part of "A." In other words, "covering A" includes not only the case of "covering all of A" but also the case of "covering only a part of A." "A" refers to, for example, the end face, side face, or main surface of a specific member such as a layer or a terminal.

[0055] 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 between similar components and to distinguish between components.

[0056] In this specification, the "end face" of a certain component refers to a face connecting two main faces of the certain component that face back to back.

[0057] (Embodiment 1) [Overall configuration] First, the configuration of the battery according to the first embodiment will be described.

[0058] FIG. 1 is a perspective view of a battery 1 according to the present embodiment. FIG. 2 is a cross-sectional view of the battery 1 according to the present embodiment. FIG. 3 is another cross-sectional view of the battery 1 according to the present embodiment. In FIG. 1, the shapes of an electrode current collector 50 and a counter electrode current collector 10 that are not actually visible are shown by dashed lines. FIG. 2 shows a cross-section along the stacking direction passing through line II-II in FIG. 1. FIG. 3 shows a cross-section along the stacking direction passing through line III-III in FIG. 1.

[0059] 1 to 3, the battery 1 includes a plurality of power generating elements 70, an electrode current collector 50, a plurality of counter electrode current collectors 10, a first insulating member 60, a second insulating member 61, and a third insulating member 62. The battery 1 is, for example, an all-solid-state battery.

[0060] The battery 1 has a schematic shape of a rectangular parallelepiped. The battery 1 may also have a schematic shape of a flattened rectangular parallelepiped. Here, "flat" means that the thickness (e.g., the length in the z-axis direction) is shorter than each side of the main surface (e.g., the length in each of the x-axis and y-axis directions) or the maximum width. In the drawings related to this specification, the thicknesses of the layers and current collectors are exaggerated to make the layer structure of the battery 1 easier to understand.

[0061] [Power generation element] The multiple power generating elements 70 are stacked in a predetermined direction (z-axis direction) with the electrode current collector 50 or the counter electrode current collector 10 sandwiched between adjacent power generating elements 70. The direction in which the multiple power generating elements 70 are stacked and arranged may be slightly curved or tilted as long as it is substantially along the z-axis direction. The power generating element 70 is the smallest component of the power generating section of the battery and is also referred to as a unit cell. The multiple power generating elements 70 are stacked so as to be electrically connected in parallel. In the illustrated example, the battery 1 includes eight power generating elements 70, but this is not limited to this. As will be described later, the power generating elements 70 are stacked on both sides of the multiple electrode current collecting sections 51, so the number of power generating elements 70 is, for example, an even number of four or more.

[0062] The shape of the power generating element 70 in plan view is, for example, a rectangle. In this embodiment, the shape of the power generating element 70 in plan view is a rectangle that includes two opposing sides parallel to the x-axis direction and two opposing sides parallel to the y-axis direction.

[0063] Each of the plurality of power generating elements 70 includes an electrode layer 40, a counter electrode layer 20, and a solid electrolyte layer 30. The electrode layer 40 and the counter electrode layer 20 each contain an active material and are also referred to as an electrode active material layer and a counter electrode active material layer. In each of the plurality of power generating elements, the electrode layer 40, the solid electrolyte layer 30, and the counter electrode layer 20 are stacked in this order substantially along the z-axis direction.

[0064] The electrode layer 40 is one of the positive electrode layer and the negative electrode layer of the power-generating element 70. The counter electrode layer 20 is the other of the positive electrode layer and the negative electrode layer of the power-generating element 70. The following describes an example in which the electrode layer 40 is the negative electrode layer and the counter electrode layer 20 is the positive electrode layer. In this case, as described below, when the power-generating element 70 is formed on the electrode current collector 50, the electrode layer 40, which is the negative electrode layer, is disposed on the electrode current collector 50 side of the power-generating element 70. By forming the electrode layer 40 large, it becomes easier to form the solid electrolyte layer 30 and the counter electrode layer 20, which are subsequently formed, and productivity can be improved. Furthermore, by forming the electrode layer 40 large as the negative electrode layer, it becomes easier to accept ions from the positive electrode layer, which can suppress metal deposition and improve reliability even when productivity is increased.

[0065] The multiple power generating elements 70 are substantially identical in configuration and shape to one another. The order of the layers constituting the power generating elements 70 is reversed between two adjacent power generating elements 70. In other words, the multiple power generating elements 70 are stacked side by side along the z-axis direction, with the order of the layers constituting the power generating elements 70 alternating. This allows the multiple power generating elements 70 to be stacked so that they are electrically connected in parallel. Furthermore, for example, when viewed along the z-axis direction, the outer edges of the multiple power generating elements 70 are aligned.

[0066] Among the multiple power generating elements 70, two adjacent power generating elements 70 are stacked with an electrode current collector 50 or a counter electrode current collector 10 interposed therebetween. Adjacent power generating elements 70 are stacked so that the electrode layers 40 or the counter electrode layers 20 face each other. Therefore, an electrode current collector 50 is disposed between the facing electrode layers 40, and a counter electrode current collector 10 is disposed between the facing counter electrode layers 20. Each of the multiple power generating elements 70 is sandwiched between the electrode current collector 50 and the counter electrode current collector 10 without another power generating element 70 interposed therebetween. In each power generating element 70, the electrode layer 40 contacts the electrode current collector 50, and the counter electrode layer 20 contacts the counter electrode current collector 10.

[0067] At the end surface 70a of the power generating element 70 in a direction intersecting the x-axis direction, specifically in the y-axis direction perpendicular to the x-axis direction, the end surfaces of the counter electrode layer 20, the solid electrolyte layer 30, and the electrode layer 40 are flush with each other. Furthermore, in the y-axis direction, the end surface 50a of the electrode current collector 51 of the electrode current collector 50 is flush with the end surfaces 70a of the two power generating elements 70 stacked on both sides of the electrode current collector 51. The flush, connected surface between the end surface 50a of the electrode current collector 51 and the end surfaces 70a of the two power generating elements 70 is, for example, a cut surface formed by collective cutting. The end surfaces 70a of the multiple power generating elements 70 are, for example, parallel to the z-axis direction and are at the same position when viewed along the z-axis direction.

[0068] Each of the power generating elements 70 has a first main surface 70b located on the electrode current collector 50 side (specifically, the electrode current collector 51 side) and a second main surface 70c facing away from the first main surface 70b and inclined relative to the first main surface 70b. The first main surface 70b is closer to the electrode current collector 50 than the second main surface 70c and is the surface where the electrode layer 40 of the power generating element 70 is electrically connected to the electrode current collector 50. The second main surface 70c is closer to the counter electrode current collector 10 than the first main surface 70b and is the surface where the counter electrode layer 20 of the power generating element 70 is electrically connected to the counter electrode current collector 10. The second main surface 70c is inclined relative to the first main surface 70b because the power generating element 70 has a thickness distribution. The thickness of the power generating element 70 varies linearly, for example, as it progresses in a predetermined direction. Specifically, each layer of the power generating element 70 has a thickness distribution. Furthermore, the thickness of at least the electrode layer 40 and the counter electrode layer 20 of the power generating element 70 decreases in the same direction. This maintains a balance between the exchange of ions when the battery 1 functions, even if there is a distribution in the thickness of each layer of the power generating element 70, thereby improving the reliability of the battery 1.

[0069] The direction in which the thickness of the power generating element 70 decreases due to the inclination of the second main surface 70c relative to the first main surface 70b intersects with the x-axis direction, which is the direction in which the electrode current collector 50 is folded back. Specifically, the direction in which the thickness of the power generating element 70 decreases due to the inclination of the second main surface 70c relative to the first main surface 70b is along the y-axis direction, which is perpendicular to the x-axis direction.

[0070] In this embodiment, the direction in which the thickness of each of the power generating elements 70 decreases due to the inclination of the second main surface 70c relative to the first main surface 70b is the same for each of the power generating elements 70. In the example shown, the thickness of each of the power generating elements 70 decreases toward the negative side in the y-axis direction. Furthermore, the thickness of each of the power generating elements 70 is uniform and not distributed in the x-axis direction, for example.

[0071] The average thickness of the power generating element 70 is, for example, 15 μm to 750 μm, and may be 30 μm to 500 μm. The ratio of the difference between the maximum and minimum thicknesses of the power generating element 70 to the average thickness of the power generating element 70, i.e., the thickness variation of the power generating element 70, is, for example, 1% to 10%, and may be 1% to 5%. From the perspective of improving the uniformity of the battery reaction within the power generating element 70, the power generating element 70 is formed so as to reduce the difference between the maximum and minimum thicknesses of the power generating element 70. However, eliminating the difference between the maximum and minimum thicknesses of the power generating element 70 requires very precise coating, which reduces productivity. By keeping the thickness variation of the power generating element 70 within this range, the uniformity of the battery reaction within the power generating element 70 can be improved while suppressing a decrease in productivity.

[0072] Next, each layer of the power generating element 70 will be described.

[0073] The solid electrolyte layer 30 is disposed between the electrode layer 40 and the counter electrode layer 20. The solid electrolyte layer 30 contacts both the electrode layer 40 and the counter electrode layer 20. The average thickness of the solid electrolyte layer 30 is, for example, 5 μm or more and 150 μm or less.

[0074] The solid electrolyte layer 30 includes at least a solid electrolyte and may include a binder material as needed. The solid electrolyte layer 30 may include a solid electrolyte having lithium ion conductivity.

[0075] As the solid electrolyte, known materials such as lithium ion conductors, sodium ion conductors, or magnesium ion conductors can be used. Examples of solid electrolytes that can be used include solid electrolyte materials such as sulfide solid electrolytes, halogen-based solid electrolytes, and oxide solid electrolytes. As the sulfide solid electrolyte, materials capable of conducting lithium ions, such as a composite of lithium sulfide (LiS) and diphosphorus pentasulfide (P2S5), can be used. Furthermore, sulfides such as LiS-SiS2, LiS-B2S3, or LiS-GeS2 can also be used. Sulfides obtained by adding at least one of LiN, LiCl, LiBr, LiPO4, and Li4SiO4 to the above sulfides as an additive can also be used.

[0076] As an oxide solid electrolyte, materials that can conduct lithium ions include, for example, Li7La3Zr2O 12 (LLZ), Li 1.3 Al 0.3 Ti 1.7 (PO4)3(LATP) or (La,Li)TiO3(LLTO) are used.

[0077] As the binder material, for example, elastomers are used, and organic compounds such as polyvinylidene fluoride, acrylic resin, or cellulose resin may also be used.

[0078] The electrode layer 40 is in contact with a main surface of the electrode current collector 50. A current collector layer that is a layer containing a conductive material may be provided between the electrode layer 40 and the electrode current collector 50. The electrode layer 40 is disposed opposite the counter electrode layer 20 with the solid electrolyte layer 30 interposed therebetween. The average thickness of the electrode layer 40 is, for example, 5 μm or more and 300 μm or less, but is not limited to this.

[0079] The electrode layer 40 includes at least a negative electrode active material and may include at least one of a solid electrolyte, a conductive additive, and a binder material as needed. Known materials capable of occluding and releasing (inserting and desorbing, or dissolving and precipitating) lithium ions, sodium ions, or magnesium ions can be used as the negative electrode active material. Materials capable of occluding and releasing lithium ions include, for example, carbon materials such as natural graphite, artificial graphite, graphite carbon fiber, and resin-baked carbon; metallic lithium; lithium alloys; and oxides of lithium and transition metal elements.

[0080] The solid electrolyte may be any of the above-described solid electrolyte materials. The conductive additive may be, for example, a conductive material such as acetylene black, carbon black, graphite, or carbon fiber. The binder may be any of the above-described binder materials.

[0081] For example, the electrode layer 40 is produced by applying a paste-like paint, in which the materials contained in the electrode layer 40 are kneaded together with a solvent, onto the main surface of the electrode current collector 50 and drying the paint. In order to increase the density of the electrode layer 40, the electrode layer 40 may be pressed after drying.

[0082] The counter electrode layer 20 is in contact with the main surface of the counter electrode current collector 10. A current collector layer that is a layer containing a conductive material may be provided between the counter electrode layer 20 and the counter electrode current collector 10. The average thickness of the counter electrode layer 20 is, for example, but not limited to, 5 μm or more and 300 μm or less.

[0083] The counter electrode layer 20 contains at least a positive electrode active material, and may contain at least one of a solid electrolyte, a conductive additive, and a binder material, as necessary.

[0084] The positive electrode active material may be a known material capable of absorbing and releasing (inserting and desorbing, or dissolving and depositing) lithium ions, sodium ions, or magnesium ions. Examples of the positive electrode active material capable of extracting and inserting lithium ions 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).

[0085] The solid electrolyte may be the solid electrolyte material described above, the conductive additive may be the conductive material described above, and the binder may be the binder material described above.

[0086] For example, a paste-like paint prepared by kneading the materials contained in the counter electrode layer 20 together with a solvent is applied to the main surface of the solid electrolyte layer 30 and dried to produce the counter electrode layer 20. In order to increase the density of the counter electrode layer 20, the counter electrode layer 20 may be pressed after drying.

[0087] [Current collector] Next, the current collector included in the battery 1 will be described.

[0088] The electrode current collector 50 is electrically connected to each electrode layer 40 of the multiple power generating elements 70. The electrode current collector 50 serves to electrically connect the power generating elements 70 in parallel. In this specification, "electrically connected" means electrically connected so as to have substantially the same potential, unless otherwise specified. The electrode current collector 50 is in contact with each electrode layer 40 of the multiple power generating elements 70. The electrode current collector 50 is, for example, a single current collector folded zigzag in the x-axis direction.

[0089] The electrode current collector 50 has a plurality of electrode current collecting portions 51 arranged along the stacking direction (z-axis direction), electrode folded portions 52 that connect adjacent electrode current collecting portions 51 among the plurality of electrode current collecting portions 51 and are folded back in the x-axis direction, and electrode lead portions 53 that extend from the electrode current collecting portions 51 toward the outside of the battery 1. The electrode current collecting portions 51, electrode folded portions 52, and electrode lead portions 53 are names given to respective portions that are formed, for example, by processing a single member made of the same material.

[0090] Each of the multiple electrode current collectors 51 is a layered portion on which the power generating element 70 is stacked. The electrode current collectors 51 overlap the power generating element 70 in a planar view. The multiple electrode current collectors 51 are lined up along the z-axis direction at a predetermined interval. Adjacent electrode current collectors 51 in the z-axis direction are connected by an electrode folded portion 52. The power generating element 70 is stacked on both surfaces of each of the multiple electrode current collectors 51 such that the electrode layer 40 is electrically connected to the electrode current collector 50. In other words, the electrode layer 40 is arranged on the side of the electrode current collector 51 in the power generating element 70, and both surfaces of the electrode current collector 51 are in contact with the electrode layer 40. For example, the multiple electrode current collectors 51 are parallel to each other.

[0091] The electrode folded portion 52 is a folded portion formed by folding the electrode current collector 50 between adjacent electrode current collectors 51. The electrode current collector 50 is folded in a zigzag manner, and thus has an electrode folded portion 52 folded from the positive side toward the negative side in the x-axis direction and an electrode folded portion 52 folded from the negative side toward the positive side in the x-axis direction. The electrode current collector 50 has, for example, multiple electrode folded portions 52. In the illustrated example, the electrode current collector 50 is folded three times, and thus has three electrode folded portions 52. The electrode folded portion 52 covers the two electrode elements 70 that face each other by folding the electrode current collector 50 from the positive side or the negative side in the x-axis direction. A first insulating member 60 is disposed between the electrode folded portion 52 and the end face of the electrode element 70.

[0092] The electrode folded portion 52 on the side of the power generating element 70 is in contact with the first insulating member 60. This allows the battery 1 to be miniaturized, thereby improving the volumetric energy density. A gap may be provided between the electrode folded portion 52 and the first insulating member 60.

[0093] The electrode lead portion 53 is an end portion of the electrode current collector 50 that is extended to the outside of the battery 1 without being folded back. In a plan view, the electrode lead portion 53 protrudes in the x-axis direction further than the other portions of the battery 1. The electrode lead portion 53 is exposed and is used as an electrode terminal of the battery 1. In this embodiment, the electrode current collector 50 has two electrode lead portions 53, and both of the two electrode lead portions 53 are extended to the negative side of the x-axis direction. The direction in which the two electrode lead portions 53 are extended is determined by the number of times the electrode current collector 50 is folded back. Therefore, depending on the number of times the electrode current collector 50 is folded back, one of the two electrode lead portions 53 is extended to the negative side of the x-axis direction, and the other is extended to the positive side of the x-axis direction. Note that the battery 1 may be provided with another terminal structure instead of the electrode lead portion 53.

[0094] Known materials can be used as the material for the electrode current collector 50. For example, the electrode current collector 50 may be made of a foil, plate, or mesh-like material made of copper, aluminum, nickel, iron, stainless steel, platinum, gold, or an alloy of two or more of these metals. The thickness of the electrode current collector 50 is, for example, 5 μm or more and 100 μm or less, but is not limited to this.

[0095] The multiple counter electrode current collectors 10 are electrically connected to the counter electrode layers 20 of the power generating elements 70. That is, the counter electrode layers 20 of each of the multiple power generating elements 70 are electrically connected to one of the multiple counter electrode current collectors 10. The multiple counter electrode current collectors 10 are lined up along the stacking direction (z-axis direction).

[0096] The counter electrode current collector 10 overlaps the power generating element 70 in a plan view. The multiple counter electrode current collectors 10 are lined up along the z-axis direction at a predetermined interval. Each of the multiple counter electrode current collectors 10 is disposed facing one of the multiple electrode current collectors 51, with the power generating element 70 sandwiched between them. A counter electrode layer 20 is disposed on the counter electrode current collector 10 side of the power generating element 70, and at least one surface of the counter electrode current collector 10 is in contact with the counter electrode layer 20. The multiple counter electrode current collectors 10 are disposed so as to sandwich each of the multiple electrode current collectors 51, each having a power generating element 70 laminated on both sides thereof, via the power generating element 70 laminated on both sides of the electrode current collector 51. In other words, between two counter electrode current collectors 10 adjacent to each other along the z-axis direction among the multiple counter electrode current collectors 10, two power generating elements 70 laminated on both sides of one of the multiple electrode current collectors 51 are disposed. In the battery 1, a counter electrode current collector 10 and a laminate structure composed of two power generating elements 70 stacked on both sides of an electrode current collector 51 and the electrode current collector 51 are alternately stacked side by side along the z-axis direction. Therefore, in the battery 1, the top and bottom current collectors are counter electrode current collectors 10. Furthermore, of the multiple counter electrode current collectors 10, the counter electrode current collectors 10 other than the top and bottom are positioned between two power generating elements 70 that face each other when the electrode current collector 50 is folded back.

[0097] Each of the multiple counter electrode current collectors 10 is a gradient current collector having a gradient structure portion 10a with a thickness distribution. The gradient structure portion 10a is laminated on the counter electrode layer 20 of the power generating element 70. The gradient structure portion 10a is a portion of the counter electrode current collector 10 whose thickness changes continuously as it progresses in a predetermined direction. The thickness of the gradient structure portion 10a changes linearly as it progresses in the predetermined direction, for example. In the counter electrode current collector 10, the gradient structure portion 10a is disposed opposite the electrode current collector 51 across the power generating element 70 and is electrically connected to the counter electrode layer 20 of the power generating element 70. In this embodiment, each of the multiple counter electrode current collectors 10 is entirely composed of the gradient structure portion 10a. Note that the counter electrode current collector 10 may include a flat portion without a thickness distribution, as long as the region laminated on the counter electrode layer 20 is composed of the gradient structure portion 10a.

[0098] The thickness of the inclined structure portion 10a increases as the thickness of the power generating element 70 decreases due to the inclination of the second main surface 70c relative to the first main surface 70b. In other words, the inclined structure portion 10a is inclined so that the influence of the thickness distribution of the power generating element 70 is mitigated across the entire battery 1 by stacking the inclined structure portion 10a on the power generating element 70. Therefore, the inclined structure portion 10a in the counter electrode current collector 10 can reduce the thickness distribution across the entire battery 1. Furthermore, the thickness of the inclined structure portion 10a is uniform and not distributed in, for example, the x-axis direction. The inclined structure portion 10a has, for example, a trapezoidal or wedge-shaped cross-section in a cross section parallel to the y-axis and z-axis directions (a cross section perpendicular to the x-axis direction).

[0099] The average thickness of the inclined structure portion 10a is, for example, not less than 5 μm and not more than 100 μm.

[0100] The difference between the maximum and minimum thicknesses of the inclined structure portion 10a is, for example, 15 μm or less. This allows the inclined structure portion 10a to be easily formed. In this case, even if the average thickness of the power generating elements 70 is 150 μm and the thickness variation of the power generating elements 70 is at most 5%, for example, the influence of the thickness variation of the two power generating elements 70 on the thickness distribution of the entire battery 1 can be completely mitigated. The difference between the maximum and minimum thicknesses of the inclined structure portion 10a is, for example, 3 μm or more. In this specification, the maximum and minimum thicknesses of the inclined structure portion 10a refer to the maximum and minimum thicknesses of the inclined structure portion 10a in the region where the counter electrode layer 20 is laminated.

[0101] Furthermore, the ratio of the maximum thickness to the minimum thickness of the inclined structure portion 10a is, for example, 3.5 or less. This allows the inclined structure portion 10a to be easily formed. For example, in the inclined structure portion 10a, if the minimum thickness is 6 μm and the maximum thickness is 21 μm, the ratio of the maximum thickness to the minimum thickness is 3.5, and if the minimum thickness is 20 μm and the maximum thickness is 35 μm, the ratio is 1.75. Furthermore, the ratio of the maximum thickness to the minimum thickness of the inclined structure portion 10a is, for example, 1.15 or more.

[0102] As shown in FIG. 3 , the difference between the maximum and minimum thicknesses of the inclined structure portions 10a of the counter electrode current collector 10 located at the ends (i.e., the bottom and top) in the stacking direction of the battery 1 is smaller than the difference between the maximum and minimum thicknesses of the inclined structure portions 10a of the counter electrode current collector 10 located between the opposing power generating elements 70 stacked on adjacent electrode current collectors 51. The inclined structure portions 10a of the counter electrode current collector 10 located at the ends and stacked on one power generating element 70 have fewer stacked power generating elements 70 than the inclined structure portions 10a of the counter electrode current collector 10 sandwiched between two power generating elements 70. Therefore, by adjusting the difference between the maximum and minimum thicknesses of the inclined structure portions 10a according to the number of stacked power generating elements 70, the top and bottom surfaces of the battery 1 can be made closer to parallel. The upper surface of the top counter electrode current collector 10 and the lower surface of the bottom counter electrode current collector 10, i.e., the top and bottom surfaces of the battery 1, are, for example, parallel to each other.

[0103] In this embodiment, the counter electrode current collector 10 located between the power generating elements 70 stacked on adjacent electrode current collecting parts 51 and facing each other is an example of a first inclined current collector. The counter electrode current collector 10 located at the end of the stacking direction of the battery 1 is an example of a second inclined current collector.

[0104] The difference between the maximum and minimum thicknesses of the inclined structure portion 10a of the counter electrode current collector 10 located between the power generating elements 70 stacked on adjacent electrode current collectors 51 and facing each other is, for example, twice the difference between the maximum and minimum thicknesses of the power generating elements 70. Furthermore, the difference between the maximum and minimum thicknesses of the inclined structure portion 10a of the counter electrode current collector 10 located at the end of the stacking direction of the battery 1 is, for example, the same as the difference between the maximum and minimum thicknesses of the power generating elements 70. This allows the overall thickness of the battery 1 to be uniform.

[0105] The counter electrode current collector 10 may be made of a foil, plate, or mesh-like material such as copper, aluminum, nickel, iron, stainless steel, platinum, or gold, or an alloy of two or more of these metals. As will be described below, the counter electrode current collector 10 may be made of a metal foil in combination with at least one of a conductive resin layer and a support member.

[0106] [Configuration of counter electrode current collector] Here, the detailed configuration of the counter electrode current collector 10 will be described.

[0107] FIG. 4A is a cross-sectional view of a counter electrode current collector 10 according to the present embodiment.

[0108] 4A, the counter electrode current collector 10 is made of a metal foil 11 having a thickness distribution. The metal foil 11 has a main surface 11a and a main surface 11b facing away from the main surface 11a and inclined relative to the main surface 11a. The main surface 11b is inclined relative to the main surface 11a so that the thickness of the metal foil 11 increases toward the negative side in the y-axis direction.

[0109] Counter electrode current collector 10 is formed, for example, by processing metal foil 11 so as to have a thickness distribution by a rolling method during the production of metal foil 11. Counter electrode current collector 10 may also be formed by depositing metal on metal foil having a uniform thickness using an electrolytic plating method or the like so as to have a thickness distribution.

[0110] The metal foil 11 is made of, for example, copper, aluminum, nickel, iron, stainless steel, platinum, or gold, or an alloy of two or more of these metals.

[0111] In this way, since the counter electrode current collector 10 is made of the metal foil 11, the configuration can be simplified.

[0112] The counter electrode current collector 10 is not limited to the example made of the metal foil 11 having a thickness distribution. For example, the battery 1 may include a counter electrode current collector as shown in Figures 4B to 4F as a gradient current collector instead of the counter electrode current collector 10.

[0113] 4B to 4F are cross-sectional views of other examples of the counter electrode current collector according to the present embodiment.

[0114] First, counter electrode current collector 10A will be described as another example of a counter electrode current collector according to the present embodiment. As shown in Fig. 4B, counter electrode current collector 10A is made of metal foil 11 and conductive resin layer 12 having a thickness distribution and laminated on metal foil 11. Similarly to counter electrode current collector 10, counter electrode current collector 10A is entirely made up of inclined structure portion 10Aa.

[0115] The conductive resin layer 12 is laminated on the principal surfaces 11a and 11b of the metal foil 11 and is in contact with the principal surfaces 11a and 11b. The conductive resin layer 12 covers the entire surfaces of the principal surfaces 11a and 11b. Note that the conductive resin layer 12 does not have to cover the entire surfaces of the principal surfaces 11a and 11b as long as it is formed in the region of the counter electrode current collector 10A where the counter electrode layer 20 is laminated.

[0116] The conductive resin layer 12 has a principal surface 12a located on the metal foil 11 side and a principal surface 12b facing away from the principal surface 12a and inclined relative to the principal surface 12a. The principal surface 12b is inclined relative to the principal surface 12a so that the thickness of the conductive resin layer 12 increases toward the negative side in the y-axis direction. Therefore, the thicknesses of the metal foil 11 and the conductive resin layer 12 increase in the same direction. This results in a greater thickness distribution of the counter electrode current collector 10A than when the counter electrode current collector is formed using only the metal foil 11.

[0117] The conductive resin layer 12 contains, for example, fine particles of metal, carbon, or a material containing these as its main component, and a resin. The shape of the fine particles is not particularly limited and may be spherical, fibrous, or scaly. The conductive resin layer 12 may be carbon coated. This allows the counter electrode current collector 10A and the counter electrode layer 20 to be connected with low resistance.

[0118] The conductive resin layer 12 is formed, for example, by preparing a slurry by dispersing the above-described fine particles and resin in a solvent, applying the slurry using a coating process such as die coating, and drying it. In this way, since the conductive resin layer 12 can be prepared by coating or the like, it is easy to adjust the thickness distribution and form the counter electrode current collector 10A having the sloped structure portion 10Aa.

[0119] Next, as another example of a counter electrode current collector according to the present embodiment, counter electrode current collector 10B will be described. As shown in Fig. 4C, counter electrode current collector 10B is made of metal foil 13 having a uniform thickness and conductive resin layer 14 laminated on metal foil 13.

[0120] The metal foil 13 is a flat plate with a uniform thickness. The metal foil 13 has a main surface 13a and a main surface 13b facing away from and parallel to the main surface 13a. Similarly to the counter electrode current collector 10, the counter electrode current collector 10B is entirely composed of an inclined structure portion 10Ba.

[0121] The conductive resin layer 14 is laminated on the principal surfaces 13a and 13b of the metal foil 13 and is in contact with the principal surfaces 13a and 13b. The conductive resin layer 14 covers the entire surfaces of the principal surfaces 13a and 13b. Note that the conductive resin layer 14 does not have to cover the entire surfaces of the principal surfaces 13a and 13b as long as it is formed in the region of the counter electrode current collector 10B where the counter electrode layer 20 is laminated.

[0122] The conductive resin layer 14 has a main surface 14a located on the metal foil 13 side and a main surface 14b facing away from the main surface 14a and inclined relative to the main surface 14a. The main surface 14b is inclined relative to the main surface 14a so that the thickness of the conductive resin layer 14 increases toward the negative side in the y-axis direction.

[0123] In this way, the conductive resin layer 14 can be formed by coating or the like, similarly to the conductive resin layer 12, and therefore the thickness distribution can be easily adjusted. Therefore, in the counter electrode current collector 10B, the sloped structure portion 10Ba can be formed simply by laminating the conductive resin layer 14 on the metal foil 13, which is easily prepared and has a uniform thickness.

[0124] Next, counter electrode current collector 10C will be described as another example of a counter electrode current collector according to the present embodiment. As shown in Fig. 4D, counter electrode current collector 10C is made up of support member 15 having a thickness distribution and metal foil 16 covering support member 15. Similarly to counter electrode current collector 10, counter electrode current collector 10C is entirely made up of sloped structure portion 10Ca.

[0125] Support member 15 is a plate-like member composed entirely of inclined structure portions 15c having a thickness distribution. Support member 15 has main surface 15a and main surface 15b facing away from main surface 15a and inclined relative to main surface 15a. Main surface 15b is inclined relative to main surface 15a so that the thickness of inclined structure portions 15c increases toward the negative side in the y-axis direction.

[0126] In the illustrated example, the cross-sectional shape of the inclined structure portion 15c is wedge-shaped, but it may also be trapezoidal.

[0127] As the material for the support member 15, for example, resin is used from the viewpoints of formability for imparting the inclined shape and weight. Metal or ceramic may also be used as the material for the support member 15. Furthermore, the support member 15 may be conductive or insulating.

[0128] The metal foil 16 covers the principal surfaces 15a and 15b. The metal foil 16 is bent, for example, at the end on the positive side in the y-axis direction of the inclined structure portion 15c, and integrally covers the entire principal surfaces 15a and 15b. The metal foil 16 may be directly bonded to the inclined structure portion 15c, or may be bonded to the inclined structure portion 15c with an adhesive or the like. The thickness of the metal foil 16 is, for example, uniform. In the counter electrode current collector 10C, a counter electrode layer 20 is laminated on the metal foil 16.

[0129] In this way, in the counter electrode current collector 10C, the inclined structure portion 10Ca can be formed using a support member 15 covered with a metal foil 16 and having a thickness distribution. The material of the support member 15 can be selected regardless of the electrical connection with the counter electrode layer 20 of the power generating element 70, so it can be easily processed into a desired shape. For example, the difference between the maximum and minimum thicknesses of the inclined structure portion 10Ca can be set to 15 μm or more. Therefore, even if the average thickness of the power generating element 70 increases and the thickness distribution of the power generating element 70 also increases accordingly, the thickness distribution of the battery 1 can be reduced. The difference between the maximum and minimum thicknesses of the inclined structure portion 10Ca may be 30 μm or more, or may be 50 μm or more.

[0130] Next, counter electrode current collector 10D will be described as another example of a counter electrode current collector according to the present embodiment. As shown in Fig. 4E, counter electrode current collector 10D is made up of support member 17 having a thickness distribution and metal foil 16 covering support member 17. Counter electrode current collector 10D also has a portion formed of inclined structure portion 10Da.

[0131] The support member 17 is a plate-like member composed of an inclined structure portion 17c having a thickness distribution and a flat plate portion 17d having a uniform thickness. The inclined structure portion 17c corresponds to the inclined structure portion 15c in the counter electrode current collector 10C. The flat plate portion 17d extends from the end of the inclined structure portion 17c on the negative side in the y-axis direction toward the negative side in the y-axis direction. The support member 17 has a main surface 17a and a main surface 17b facing away from the main surface 17a.

[0132] In the inclined structure portion 17c, the main surface 17b is inclined with respect to the main surface 17a so that the thickness of the inclined structure portion 17c increases toward the negative side in the y-axis direction. In the flat plate portion 17d, the main surfaces 17a and 17b are parallel to each other.

[0133] In the illustrated example, the cross-sectional shape of the inclined structure portion 17c is wedge-shaped, but it may also be trapezoidal.

[0134] The metal foil 16 covers the principal surfaces 17a and 17b of the inclined structure portion 17c. For example, the metal foil 16 is bent at the end of the inclined structure portion 17c on the positive side in the y-axis direction, integrally covering the entire principal surfaces 17a and 17b of the inclined structure portion 17c. In the illustrated example, the metal foil 16 does not cover the principal surfaces 17a and 17b of the flat plate portion 17d. The metal foil 16 may cover the principal surfaces 17a and 17b of the flat plate portion 17d. In other words, the metal foil 16 may cover the entire principal surfaces 17a and 17b. In the counter electrode current collector 10D, the inclined structure portion 10Da is composed of the inclined structure portion 17c of the support member 17 and the metal foil 16. In the counter electrode current collector 10D, a counter electrode layer 20 is laminated on the metal foil 16.

[0135] In this way, in counter electrode current collector 10D, flat plate portion 17d having a uniform thickness is formed at the end portion, and therefore flat plate portion 17d can be used as a lead terminal that can be easily connected to the outside when support member 17 is conductive. Furthermore, by covering flat plate portion 17d with metal foil 16, the portion formed by flat plate portion 17d and metal foil 16 may be used as a lead terminal.

[0136] Next, counter electrode current collector 10E will be described as another example of a counter electrode current collector according to the present embodiment. As shown in Fig. 4F, counter electrode current collector 10E is made up of support member 17 having a thickness distribution, metal foil 16 covering support member 17, and conductive resin layer 18 covering metal foil 16. In other words, counter electrode current collector 10E has a configuration in which conductive resin layer 18 is added to counter electrode current collector 10D. Furthermore, counter electrode current collector 10E is partially made up of sloped structure portion 10Ea.

[0137] The conductive resin layer 18 covers, for example, the entire surface of the metal foil 16 opposite to the support member 17 side. The conductive resin layer 18 may have a uniform thickness or may have a thickness distribution. In the counter electrode current collector 10E, the inclined structure portion 10Ea is composed of the inclined structure portion 17c of the support member 17, the metal foil 16, and the conductive resin layer 18. In the counter electrode current collector 10E, the counter electrode layer 20 is laminated on the conductive resin layer 18.

[0138] Thus, in the counter electrode current collector 10E, the metal foil 16 is further covered with the conductive resin layer 18. Therefore, by adjusting the thickness and thickness distribution of the conductive resin layer 18, the thickness and thickness distribution of the sloped structure portion 10Ea can be easily adjusted.

[0139] The counter electrode current collector according to the present embodiment is not limited to the above example, and may further include another layer, for example.

[0140] [Insulating material] Next, referring again to FIGS. 1 to 3, the insulating members provided in the battery 1 will be described.

[0141] The first insulating members 60 cover and contact the end faces of the power generating element 70 in the x-axis direction, thereby preventing short circuits caused by contact between the power generating element 70 and the electrode folded portion 52. In the battery 1, a plurality of first insulating members 60 are provided for each power generating element 70 so as to cover the end faces of the power generating element 70 on the positive and negative sides in the x-axis direction.

[0142] For example, at the end face of the power generating element 70 in the x-axis direction, the first insulating member 60 completely covers the end face of the electrode layer 40 and the end face of the solid electrolyte layer 30, and covers a portion of the end face of the counter electrode layer 20. The first insulating member 60 is also in contact with the main surface of the electrode current collector 50. Therefore, the first insulating member 60 continuously covers from the surface of the electrode current collector 50 on which the power generating element 70 is stacked to a portion of the end face of the counter electrode layer 20 of the power generating element 70. Furthermore, the first insulating member 60 does not cover the main surface of the counter electrode layer 20. Note that the first insulating member 60 does not have to cover the end faces of the solid electrolyte layer 30 and the counter electrode layer 20. Furthermore, the first insulating member 60 may cover the main surface of the counter electrode layer 20.

[0143] The second insulating member 61 covers the end face 50a of the electrode current collector 51 and the end faces 70a of the two power generating elements 70 stacked on both sides of the electrode current collector 51. The second insulating member 61 also contacts the end faces 50a and 70a. This protects the power generating elements 70 and prevents short circuits. In the battery 1, a plurality of second insulating members 61 are provided on the positive and negative sides in the y-axis direction of the two power generating elements 70 stacked on both sides of each electrode current collector 51 to cover the electrode current collector 51 and the end faces 70a of the two power generating elements 70. The second insulating member 61 completely covers, for example, the end faces 70a of the power generating elements 70 in the y-axis direction.

[0144] The third insulating member 62 covers the end face of the power generating element 70 and the end face of the counter electrode current collector 10 in the x-axis direction. This protects the end face of the power generating element 70 and the end face of the counter electrode current collector 10 in the x-axis direction. The third insulating member 62 covers the end face of the power generating element 70 opposite to the side on which the electrode folded portion 52 of the electrode current collector 50 is arranged. In the battery 1, multiple third insulating members 62 are provided so as to cover the entire end faces of the power generating elements 70 that are not covered by the electrode folded portion 52, among the end faces of the multiple power generating elements 70 on the positive and negative sides in the x-axis direction.

[0145] The third insulating member 62 is in contact with a portion of the end face of the power generating element 70 in the x-axis direction that is not covered by the first insulating member 60. The third insulating member 62 also covers a portion of the end face of the power generating element 70 in the x-axis direction that is covered by the first insulating member 60 from the outside of the first insulating member 60.

[0146] The first insulating member 60, the second insulating member 61, and the third insulating member 62 each contain, for example, at least one of a resin and a metal oxide. Examples of the resin include silicone resin, epoxy resin, acrylic resin, and polyimide resin. The resin may be a thermosetting resin or an ultraviolet-curing resin. Examples of the metal oxide include silicon oxide, titanium oxide, and aluminum oxide.

[0147] The battery 1 does not necessarily have to include at least one of the first insulating member 60, the second insulating member 61, and the third insulating member 62.

[0148] [Manufacturing method] Next, a method for manufacturing the battery 1 according to this embodiment will be described with reference to FIGS.

[0149] FIG. 5 is a flowchart illustrating an example of a manufacturing method of a battery 1 according to the present embodiment. FIG. 6 is a perspective view of a cell stack collector 2 according to the present embodiment. FIG. 7 is a cross-sectional view of the cell stack collector 2 according to the present embodiment. FIG. 8 is another cross-sectional view of the cell stack collector 2 according to the present embodiment. FIG. 9 is a cross-sectional view illustrating a power generating element 71 having a uniform thickness. FIG. 10 is a cross-sectional view illustrating a power generating element 70 according to the present embodiment. FIG. 11 is a cross-sectional view illustrating the cell stack collector 2 according to the present embodiment folded back in a zigzag pattern. Note that FIG. 6 does not illustrate detailed configurations such as the layer structure of the power generating element 70. FIG. 7 illustrates a cross-section along the stacking direction passing through line VII-VII in FIG. 6. FIG. 8 illustrates a cross-section along the stacking direction passing through line VIII-VIII in FIG. 6. Also, FIGS. 9 and 10 illustrate cross sections at positions corresponding to FIG. 8.

[0150] As shown in FIG. 5, in the manufacturing method of the battery 1, first, a power generating element 70 is formed on both sides of an electrode current collector 50 (step S11). Specifically, as shown in FIGS. 6 and 7, a long electrode current collector 50 extending in the x-axis direction is prepared. The electrode current collector 50 has multiple electrode current collectors 51, which are multiple parts aligned along the x-axis direction. The multiple electrode current collectors 51 are spaced apart so that the multiple electrode current collectors 51 can be folded back between them in a later step. Then, an electrode layer 40, a solid electrolyte layer 30, and a counter electrode layer 20 are sequentially stacked in this order from the electrode current collector 50 side on both sides of each of the multiple electrode current collectors 51 to form a power generating element 70. Two power generating elements 70 are formed for one electrode current collector 51. As a result, multiple power generating elements 70 aligned along the x-axis direction are formed on both sides of the electrode current collector 50. Furthermore, the power generating elements 70 formed on both sides of one electrode current collector 51 are in the same position in a plan view.

[0151] The electrode layer 40, the solid electrolyte layer 30, and the counter electrode layer 20 are each laminated in this order using, for example, a coating method. By using a coating method, the power generating element 70 can be easily laminated on the electrode current collector 50. Examples of coating methods that can be used include die coating, doctor blade coating, roll coater coating, screen printing, gravure roll coating, and inkjet coating. Among these, die coating may be used as the coating method from the viewpoint of efficiently forming the electrode layer 40, the solid electrolyte layer 30, and the counter electrode layer 20 on the long electrode current collector 50.

[0152] When the coating method is used, a coating process is carried out in which materials for forming the electrode layer 40, the solid electrolyte layer 30, and the counter electrode layer 20 (the above-mentioned materials for the electrode layer 40, the solid electrolyte layer 30, and the counter electrode layer 20) are appropriately mixed with a solvent to obtain a slurry.

[0153] The solvent used in the paint-making step may be a known solvent used in producing a known all-solid-state battery (for example, a lithium-ion all-solid-state battery).

[0154] The slurry for each layer obtained in the coating process is applied to both sides of the multiple electrode current collectors 51 of the electrode current collector 50 in the order of the electrode layer 40, the solid electrolyte layer 30, and the counter electrode layer 20. For example, using a roll-to-roll process, the slurry is discharged from a die for die coating while the electrode current collector 50 flows along the x-axis direction, and the slurry is applied to the electrode current collector 50. This allows the power generating element 70 to be formed in a continuous process, thereby improving productivity. When the power generating element 70 is formed in this continuous process, the x-axis direction can also be considered the flow direction of the continuous process. For example, the die for die coating uses a die having a discharge port extending in a direction perpendicular to the x-axis direction. This makes it easy to form layers with a width corresponding to the length in the direction of extension of the discharge port. The slurry for each layer is applied sequentially, and after all layers have been applied, a heat treatment is performed, if necessary, to remove the solvent, etc.

[0155] In a coating process such as die coating, ideally, a power generating element 71 of uniform thickness is formed by coating the electrode layer 41, solid electrolyte layer 31, and counter electrode layer 21, each of which has a uniform thickness, as shown in Fig. 9. However, in reality, it is difficult to achieve a uniform thickness in the y-axis direction, which intersects with the flow direction, due to factors such as unevenness in the distance between the die used for die coating and the electrode current collector 50 and unevenness in the discharge of the slurry from the die in the direction in which the die outlet extends, and achieving this requires a lot of time for adjustments, etc. Therefore, productivity decreases when forming a power generating element 71 of uniform thickness.

[0156] Therefore, in this embodiment, as shown in FIG. 10 , the electrode layer 40, the solid electrolyte layer 30, and the counter electrode layer 20 are applied to form the power generating element 70 while allowing a predetermined thickness distribution. To balance the capacities of the electrode layer 40 and the counter electrode layer 20 at the position where they face each other, the electrode layer 40 and the counter electrode layer 20 are applied so that their thicknesses decrease in the same direction. Therefore, the thickness of the power generating element 70 as a whole decreases in a predetermined direction. This improves productivity while suppressing a decrease in reliability of the battery 1. Furthermore, in a coating process such as die coating, it is easy to improve thickness uniformity in the flow direction, and the thickness of the power generating element 70 varies in the y-axis direction, which intersects with the flow direction. Furthermore, in this embodiment, the power generating element 70 is formed using a continuous process, so the direction in which the thickness decreases is the same for all power generating elements 70 arranged along the x-axis direction. In the illustrated example, the thickness of all power generating elements 70 arranged along the x-axis direction decreases toward the negative side of the y-axis direction.

[0157] Furthermore, since the reliability of the battery 1 can be improved by making the capacity of the power generating elements 70 the same at opposing positions across the electrode current collecting portion 51, the power generating elements 70 formed on both sides of the same electrode current collecting portion 51 are also formed so that the thickness decreases as they move in the same direction (towards the negative y-axis direction).

[0158] Furthermore, when forming the power generating element 70, for example, the electrode layer 40, the solid electrolyte layer 30, and the counter electrode layer 20 are laminated in a planar view so that the areas of the electrode layer 40, the solid electrolyte layer 30, and the counter electrode layer 20 decrease in that order. It is difficult to perfectly align the electrode layer 40, the solid electrolyte layer 30, and the counter electrode layer 20 while coating, and precise alignment can lead to reduced productivity. On the other hand, due to this area relationship, even if the solid electrolyte layer 30 and the counter electrode layer 20 are misaligned, they are unlikely to protrude from the underlying layer. This ensures the reliability of the battery 1 even when the coating speed is increased. Furthermore, as described above, since the electrode layer 40 is an anode layer in this case, the anode layer is formed larger than the cathode layer, thereby suppressing metal deposition.

[0159] The electrode current collector 50, in which the power generating elements 70 are formed on both surfaces of each of the multiple electrode current collectors 51, is cut to a length in the x-axis direction that includes the number of power generating elements 70 included in the battery 1. The electrode current collector 50 is also cut to provide an area of ​​a predetermined length at the end of the electrode current collector 50 where the power generating elements 70 are not stacked (electrode lead-out portion 53 in the battery 1). This provides a cell stack current collector 2, which is the electrode current collector 50 on which the number of power generating elements 70 included in the battery 1 are stacked. Note that this cutting process may be performed at any time up until the folding back of the electrode current collector 50 is completed in step S16, which will be described later. Also, if an electrode current collector 50 of the required length is prepared in advance and the desired number of power generating elements 70 are formed, this cutting process does not need to be performed.

[0160] Next, the electrode current collector 50 and the power-generating element 70 are cut along the x-axis direction to form a cut surface 2a (step S12). Specifically, in step S12, the electrode current collector 50 and the power-generating elements 70 stacked on both sides of each of the multiple electrode current collectors 51 are cut together in the x-axis direction and along a direction intersecting (e.g., perpendicular to) the main surfaces of the power-generating element 70. For example, the counter electrode layer 20, the solid electrolyte layer 30, the electrode layer 40, and the electrode current collector 50 are cut together so that the end faces of each are flush with one another. As a result, as shown in FIG. 8 , a cut surface 2a is formed, which is composed of the end face 50a of the electrode current collector 50 (electrode current collector 51) in the y-axis direction and the end faces 70a of the two power-generating elements 70 stacked on both sides of the electrode current collector 51 in the y-axis direction. The cut surfaces 2a are formed, for example, at both end portions of the electrode current collector 50 and the power-generating element 70 in the y-axis direction. Furthermore, the end surface 70a is formed by flushing the end surfaces of the counter electrode layer 20, the solid electrolyte layer 30, and the electrode layer 40. This allows the sizes of the layers of the power generating element 70 to be made similar, even if they are different in size when the power generating element 70 is formed in step S11. The difference in size between the counter electrode layer 20 and the electrode layer 40 does not contribute to the battery capacity, so making the sizes of the layers of the power generating element 70 similar can increase the volumetric energy density of the battery 1. Furthermore, because the power generating element 70 is cut along the x-axis direction, the positions of the power generating elements 70 lined up along the x-axis direction are also aligned when viewed along the x-axis direction.

[0161] The cutting may be performed, for example, by cutting down with a blade, or by forming a slit with a rotary blade. The cutting may also be performed with a laser or a jet. After cutting, the cut surface 2a may be polished. This removes burrs and other impurities that may occur during cutting, thereby preventing short circuits and the like.

[0162] Next, the power generating elements 70 formed on both surfaces of each of the plurality of electrode current collectors 51 are subjected to a high-pressure press (step S13). This densifies the power generating elements 70, thereby improving battery performance. The high-pressure press is performed on the plurality of power generating elements 70 in a continuous process using, for example, a roll press. In this case, too, the power generating elements 70 formed on both surfaces of the plurality of electrode current collectors 51 are pressed sequentially while the electrode current collectors 50 are flowing in the x-axis direction. Therefore, in this case too, the x-axis direction is the flow direction of the continuous process. Note that the high-pressure press (step S13) may be performed before step S12, or may be performed on each layer of the power generating element 70 in parallel with step S11.

[0163] Next, first insulating members 60 are formed to cover the end faces of the power generating element 70 in the x-axis direction (step S14). As shown in Fig. 6 and Fig. 7, first insulating members 60 are formed on the positive and negative end faces in the x-axis direction of the power generating element 70 formed on both surfaces of each of the multiple electrode current collectors 51. Figs. 6 to 8 show the cell stack current collector 2 in a state where step S14 has been completed.

[0164] The first insulating member 60 can be formed, for example, by using the application method mentioned in step S11. For example, as shown in Fig. 7, the material of the first insulating member 60 is applied so as to cover from the portion in contact with the electrode current collector 50 to part of the end face of the counter electrode layer 20. The first insulating member 60 may be formed by the same method as in step S11, or by a method different from that in step S11.

[0165] The first insulating member 60 can be obtained by applying a paint in which an insulating material (e.g., a metal oxide) is dispersed in a solvent to the end surfaces of the power generating element 70 and the electrode current collector 50, and then drying to evaporate the solvent. If a resin is used as the material for the first insulating member 60, a solution in which the resin is dissolved or dispersed may be applied to the end surfaces of the power generating element 70 and the electrode current collector 50, or an ultraviolet-curable resin or a thermosetting resin may be applied to the end surfaces of the power generating element 70 and the electrode current collector 50, followed by a curing process. The solvent used to form the first insulating member 60 may be a general organic solvent or aqueous solvent that dissolves or disperses metal oxides or resins.

[0166] By forming such a first insulating member 60 covering the end face of the power generating element 70, even if stress is applied to the power generating element 70 when the electrode collector 50 is folded back, collapse of the power generating element 70 due to cracking or chipping at the end face of the power generating element 70 can be suppressed.

[0167] Next, a second insulating member 61 is formed to cover the cut surface 2a (step S15). The second insulating member 61 is formed, for example, on the cut surface 2a so as to entirely cover the end surface 70a of the power generating element 70 and the end surface 50a of the electrode current collector 51. The second insulating member 61 can be formed, for example, using the coating method mentioned in step S11.

[0168] By forming the second insulating member 61 to cover the cut surface 2a in this manner, the power generating element 70 is protected by the second insulating member 61 at the cut surface 2a, and short circuits due to contact between the counter electrode collector 10 and the power generating element 70 and the electrode current collecting portion 51 at the portions where they are close to each other can be suppressed.

[0169] The order of steps S12 to S15 is not particularly limited as long as they are performed before step S16, and may be reversed.

[0170] Next, the electrode current collector 50 is folded back in the x-axis direction so that the power generating elements 70 formed on adjacent electrode current collectors 51 among the multiple electrode current collectors 51 face each other, and a counter electrode current collector 10 is laminated on the counter electrode layer 20 of each power generating element 70 (step S16). In step S16, the electrode current collector 50 is folded back in a z-axis direction ... The counter electrode current collector 10 is also arranged so that the thickness of the inclined structure portion 10a increases as the thickness of the power generating element 70 decreases due to the inclination of the second main surface 70c relative to the first main surface 70b. This forms a stack in which multiple power generating elements 70 are stacked. The stack formed in step S16 has a configuration similar to that of the battery 1 shown in Figures 1 to 3, except that the third insulating member 62 is removed.

[0171] Specifically, when folding back the electrode current collector 50, the counter electrode current collector 10 is positioned so that it is sandwiched between the opposing power generating elements 70 by folding back the electrode current collector 50. This operation is repeated until all power generating elements 70 are stacked. As a result, for example, as shown in FIG. 11 , the electrode current collector 50 is folded back in a zigzag manner in the x-axis direction, so that all power generating elements 70 are stacked, and an electrode folded portion 52, which is the folded back portion, is formed. FIG. 11 illustrates a state in which the electrode current collector 50 (cell current collector stack 2) is folded back, excluding the counter electrode current collector 10. Furthermore, the counter electrode current collector 10 is positioned between the opposing power generating elements 70 by folding back the electrode current collector 50. In the cell current collector stack 2, a cut surface 2a is formed along the x-axis direction, and the end surface 70a of the power generating element 70 and the end surface of the electrode current collector 50 are aligned, making it easy to control the positioning when folding back. 11 is fixed, and the counter electrode current collector 10 may be inserted along the y-axis direction into the fixed folded cell current collector stack 2. This also makes it possible to fold back the electrode current collector 50 without disposing the counter electrode current collector 10 between the opposing power generating elements 70 by folding back the electrode current collector 50.

[0172] In this way, the electrode current collector 50 is folded back in a zigzag shape to form a laminate of a plurality of power generating elements 70. This eliminates the need to separate the electrode current collector 50 into individual pieces for each of the power generating elements 70, and reduces the number of steps compared to stacking the power generating elements 70 using individualized electrode current collectors, thereby improving the productivity of the battery 1.

[0173] Next, as necessary, the laminate in which the plurality of power generating elements 70 are stacked is subjected to adhesive pressing (step S17). Specifically, the laminate in which the plurality of power generating elements 70 are stacked is pressed in the stacking direction by a plate press or the like, so that the counter electrode current collector 10 and the power generating elements 70 are tightly attached to each other.

[0174] Next, a third insulating member 62 is formed to cover the end face of the power generating element 70 opposite the side where the electrode folded portion 52 of the electrode current collector 50 is located (step S18). The third insulating member 62 is also formed on both end faces in the x-axis direction of the power generating element 70 on neither of which an electrode folded portion 52 is formed. This protects the exposed portions of the end face of the power generating element 70 that are not covered by the electrode folded portion 52. The third insulating member 62 can be formed, for example, using the coating method mentioned in step S11. The formation of the third insulating member 62 (step S18) may be performed before the adhesive pressing (step S17).

[0175] Through the above steps, the battery 1 shown in FIGS. 1 to 3 is obtained.

[0176] [effect] The effects of battery 1 according to the present embodiment will be described in comparison with battery 1X according to a comparative example. Fig. 12 is a cross-sectional view of battery 1X according to the comparative example. Battery 1X differs from battery 1 according to the present embodiment in that it includes counter electrode current collector 10X with a uniform thickness instead of counter electrode current collector 10 having sloped structure portion 10a.

[0177] As described above, when power generating elements 70 with the same thickness decreasing direction are formed on both sides of multiple electrode current collectors 51 and the multiple power generating elements 70 are stacked by folding back the electrode current collectors 50, the thickness distribution of the power generating elements 70 as a whole accumulates. Therefore, as shown in FIG. 12 , when a counter electrode current collector 10X with a uniform thickness is used, the thickness distribution of the entire battery 1X becomes very large. Furthermore, the stacking direction of the power generating elements 70 is inclined from the direction perpendicular to the bottom or top surface of the battery 1X. This distorts the shape of the battery 1X, and when packaging or installing the battery 1X in a device, etc., wasteful space is likely to be formed in the battery 1X, reducing the effective volumetric energy density of the battery 1X. Furthermore, this tendency becomes more pronounced as the number of power generating elements 70 stacked increases.

[0178] 3 and other figures, the battery 1 according to this embodiment includes a counter electrode current collector 10 having a gradient structure portion 10a with a thickness distribution, which is laminated on the counter electrode layer 20 of the power generating element 70. The thickness of the gradient structure portion 10a increases as the thickness of the power generating element 70 decreases due to the gradient of the second main surface 70c relative to the first main surface 70b.

[0179] Thus, even when the power generating element 70 is formed while allowing for some thickness variation to enhance productivity, the inclined structure portion 10a of the counter electrode current collector 10 can mitigate the influence of the thickness variation of the power generating element 70 on the entire battery 1, thereby reducing the thickness variation. Furthermore, the stacking direction of the power generating elements 70 can be made closer to a direction perpendicular to the bottom or top surface of the battery 1. This reduces distortion of the shape of the battery 1, and reduces the formation of wasted space when packaging the battery 1 or when housing the battery 1 in a device, etc. This increases the productivity and volumetric energy density of the battery 1. In particular, when power generating elements 70 with the same thickness decreasing direction are stacked, the thickness variation accumulates. However, by stacking the inclined structure portion 10a of the counter electrode current collector 10 on each power generating element 70, a battery 1 with a reduced cumulative thickness variation can be realized.

[0180] (Embodiment 2) Next, a description will be given of embodiment 2. The following description will focus on the differences from embodiment 1, and the description of commonalities will be omitted or simplified.

[0181] 13 is a cross-sectional view of a battery 101 according to this embodiment, taken along a line corresponding to that of FIG.

[0182] As shown in FIG. 13 , the battery 101 according to the present embodiment differs from the battery 1 according to the first embodiment in that some of the plurality of counter electrode current collectors 10 are replaced with counter electrode current collectors 110, and in that the plurality of power generating elements 70 include power generating elements 70 in which the directions in which the thicknesses of the power generating elements 70 decrease are opposite to each other.

[0183] In the multiple power generating elements 70, the power generating elements 70 that face each other by folding back the electrode current collector 50 have their second main surfaces 70c inclined relative to the first main surface 70b, and the directions in which their thicknesses decrease are opposite to each other. Therefore, even when multiple power generating elements 70 are stacked, the thickness distribution of the power generating elements 70 is unlikely to accumulate. In other words, the thickness distribution of the entire battery 101 can be made smaller. This allows the volumetric energy density of the battery 101 to be increased. Of the two power generating elements 70 that face each other by folding back the electrode current collector 50, one is an example of a first power generating element, and the other is an example of a second power generating element.

[0184] The counter electrode current collector 110 is disposed between the opposing power generating elements 70 by folding back the electrode current collector 50. In the battery 101, the uppermost and lowermost counter electrode current collectors are the counter electrode current collectors 10.

[0185] Thus, in the battery 101, some of the counter electrode current collectors are counter electrode current collectors 10 having the inclined structural portion 10a. In the battery 101, even if a plurality of power generating elements 70 are stacked, the thickness distribution of the power generating elements 70 is unlikely to accumulate. Therefore, even if only some of the counter electrode current collectors are counter electrode current collectors 10 having the inclined structural portion 10a, the effect of the thickness distribution of the power generating elements 70 on the volumetric energy density can be sufficiently reduced. For example, the top and bottom surfaces of the battery 101 are parallel to each other.

[0186] For example, in step S11 of the manufacturing method of the battery 1 described above, the battery 101 is manufactured by forming the power generating element 70 on adjacent electrode current collectors 51 among the plurality of electrode current collectors 51 aligned in the x-axis direction so that the directions in which the thickness of the power generating element 70 decreases are opposite to each other. For example, in a continuous process of forming the power generating element 70, the power generating element 70 is formed on each of the plurality of electrode current collectors 51 aligned in the x-axis direction, skipping one electrode current collector 51, so that the directions in which the thickness of the power generating element 70 decreases are the same. Next, the power generating element 70 is formed on the skipped electrode current collector 51 so that the thickness of the power generating element 70 decreases in the opposite direction to the power generating element 70 already formed. The battery 101 can be manufactured by performing steps S12 to S18 using the electrode current collector 50 on which the power generating element 70 has been formed in this manner.

[0187] Even if the direction in which the thickness decreases is the same for each of the multiple power generating elements 70, if the thickness distribution of the multiple power generating elements 70 is small, a counter electrode current collector 10 having an inclined structure portion 10a only on some (for example, the top and bottom) of the multiple counter electrode current collectors may be used, as in battery 101.

[0188] (Embodiment 3) Next, a description will be given of embodiment 3. The following description will focus on the differences from embodiments 1 and 2, and the description of commonalities will be omitted or simplified.

[0189] 14 is a cross-sectional view of a battery 201 according to this embodiment, taken along a line corresponding to that of FIG.

[0190] As shown in FIG. 14, the battery 201 according to this embodiment differs from the battery 1 according to the first embodiment in that it further includes a connecting member 210.

[0191] The connecting member 210 is connected to one end of each of the multiple counter electrode current collectors 10. In the example shown, the connecting member 210 is connected to an end portion on the negative side in the y-axis direction of each of the multiple counter electrode current collectors 10. The portion of the counter electrode current collector 10 that is connected to the connecting member 210 is the end portion of the counter electrode current collector 10 in the direction in which the thickness of the sloped structure portion 10a increases. The connecting member 210 also covers the end surface 70a on the negative side in the y-axis direction of each of the multiple power generating elements 70.

[0192] The connecting member 210 and the plurality of counter electrode current collectors 10 are, for example, integrally formed to form a comb-shaped composite current collector 211. That is, the connecting member 210 and the plurality of counter electrode current collectors 10 are, for example, integrated. The connecting member 210 is formed, for example, using the same metal as the counter electrode current collectors 10. Note that the connecting member 210 and the plurality of counter electrode current collectors 10 may be formed as separate members and then connected. Furthermore, as in the counter electrode current collectors exemplified in FIGS. 4B to 4F , the composite current collector 211 may be formed by combining two or more of a metal foil, a conductive resin layer, and a support member. For example, the composite current collector may be formed by a support member having a shape similar to that of the composite current collector 211 and a metal foil covering the support member.

[0193] The plurality of counter electrode current collectors 10 correspond to the plurality of comb portions of the comb shape of the composite current collector 211. The connection member 210 corresponds to the base portion of the comb shape of the composite current collector 211.

[0194] The connecting member 210 electrically connects, for example, the plurality of counter electrode current collectors 10 to one another. Therefore, the composite current collector 211 functions to electrically connect the power generating elements 70 in parallel.

[0195] The power generating element 70 side of the connecting member 210 is in contact with the second insulating member 61. This allows the battery 201 to be miniaturized, thereby improving the volumetric energy density. A gap may be provided between the connecting member 210 and the second insulating member 61.

[0196] The connecting member 210 is exposed and is used, for example, as a counter electrode terminal of the battery 201. This eliminates the need for a process for forming a counter electrode terminal, thereby improving the productivity of the battery 201. Furthermore, since the terminal portion can be made space-saving, the volumetric energy density of the battery 201 can be improved.

[0197] The battery 201 is formed, for example, in step S16 of the manufacturing method of the battery 1 described above, by folding back the electrode current collector 50 and inserting the counter electrode current collectors 10 other than the top and bottom ones of the multiple counter electrode current collectors 10 between the opposing power generating elements 70. For example, the folded cell current collector 2 is fixed in the state shown in FIG. 11 . Then, the counter electrode current collectors 10 are inserted along the y-axis into the folded and fixed cell current collector 2 so that the two power generating elements 70 stacked on both sides of one electrode current collector 51 are positioned between two counter electrode current collectors 10 adjacent along the z-axis direction among the multiple counter electrode current collectors 10. This results in the battery 201 shown in FIG. 14.

[0198] In this way, by folding back the electrode current collector 50, the counter electrode current collector 10, which is the comb portion of the composite current collector 211, is inserted between the opposing power generating elements 70. This allows multiple counter electrode current collectors 10 to be stacked simultaneously on the counter electrode layer of the power generating element 70, thereby improving productivity. Furthermore, for example, when the difference between the long and short sides of the power generating element 70 in plan view is large, or when the power generating element 70 is small in size for use in substrate mounting, the terminal structure for electrically connecting multiple counter electrode current collectors 10 to each other tends to be relatively large. Therefore, by using a comb-shaped composite current collector 211 to which multiple counter electrode current collectors 10 are connected in advance, the multiple counter electrode current collectors 10 can be electrically connected by the connecting member 210, making it possible to miniaturize the terminal structure and increase the volumetric energy density.

[0199] (Other embodiments) While the battery according to the present disclosure has been described above 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 embodiments and other forms constructed by combining some of the components of the embodiments are also included in the scope of the present disclosure.

[0200] For example, in the above embodiment, the power generating element 70 is laminated on both sides of all of the plurality of electrode current collectors 51, but this is not limited to this. For example, the power generating element 70 may be laminated on only one side of the electrode current collector 51 that is located closest to the end of the electrode current collector 50 among the plurality of electrode current collectors 51. This allows the uppermost and lowermost current collectors to be electrode current collectors 50 (specifically, electrode current collectors 51). In this case, the number of power generating elements 70 may be an odd number.

[0201] Furthermore, for example, in the above embodiment, a plurality of power generating elements 70 are stacked, but this is not limiting. A battery according to the present disclosure may be, for example, a battery configured with one power generating element 70, one counter electrode current collector 10, and one electrode current collector 51. A battery according to the present disclosure may be, for example, a battery configured with one electrode current collector 51, two power generating elements 70 formed on both sides of the electrode current collector 51, and two counter electrode current collectors 10 arranged so as to sandwich the two power generating elements 70 formed on both sides of the electrode current collector 51.

[0202] Furthermore, for example, in the above embodiment, a single electrode current collector 50 that is connected as a whole is used, but this is not limited to this. A plurality of individual flat electrode current collectors may be used as the electrode current collector. In other words, the electrode current collector may be composed of only the portion corresponding to the electrode current collecting portion 51.

[0203] Furthermore, for example, in the above embodiment, the power generating element 70 is formed by stacking the electrode layer 40, the solid electrolyte layer 30, and the counter electrode layer 20 on the electrode current collector 50, but this is not limiting. For example, the electrode layer 40 or the electrode layer 40 and the solid electrolyte layer 30 may be stacked on the electrode current collector 50, and the counter electrode layer 20 or the counter electrode layer 20 and the solid electrolyte layer 30 may be stacked on the counter electrode current collector 10. The power generating element 70 may then be formed by stacking the counter electrode current collector 10 on the electrode current collector 50 such that the electrode layer 40 or the electrode layer 40 and the solid electrolyte layer 30 on the electrode current collector 50 face the counter electrode layer 20 or the counter electrode layer 20 and the solid electrolyte layer 30 on the counter electrode current collector 10.

[0204] Furthermore, the above-described embodiments can be modified, substituted, added, omitted, and the like in various ways within the scope of the claims or their equivalents. [Industrial Applicability]

[0205] The battery according to the present disclosure can be used, for example, as a secondary battery such as an all-solid-state battery used in various electronic devices or automobiles. [Explanation of symbols]

[0206] 1, 101, 201 batteries 2 Cell stack current collector 2a Cut surface 10, 10A, 10B, 10C, 10D, 10E, 110 Counter electrode current collector 10a, 10Aa, 10Ba, 10Ca, 10Da, 10Ea, 15c, 17c Slope structure 11, 13, 16 Metal foil 11a, 11b, 12a, 12b, 13a, 13b, 14a, 14b, 15a, 15b, 17a, 17b Main surface 12, 14, 18 Conductive resin layer 15, 17 Support members 17d Flat plate part 20 Opposite Layer 30 Solid electrolyte layer 40 electrode layer 50 Electrode current collector 50a end face 51 Electrode current collector 52 Electrode folded part 53 Electrode extraction part 60 First insulating member 61 Second insulating member 62 Third insulating member 70 Power generation elements 70a end face 70b 1st principal surface 70c 2nd principal surface 210 Connecting member 211 Composite current collector

Claims

1. an electrode current collector; a power generating element having a structure in which an electrode layer, a solid electrolyte layer, and a counter electrode layer are laminated in this order from the electrode current collector side on the electrode current collector; a gradient current collector having a gradient structure portion laminated on the counter electrode layer of the power generating element, the power-generating element has a first main surface located on the electrode current collector side and a second main surface facing away from the first main surface and inclined relative to the first main surface, the thickness of the inclined structure portion increases as the thickness of the power generating element decreases due to the inclination of the second main surface with respect to the first main surface, battery.

2. the difference between the maximum thickness and the minimum thickness of the inclined structure portion is 15 μm or less; The battery of claim 1 .

3. the ratio of the maximum thickness to the minimum thickness of the inclined structure portion is 3.5 or less; The battery of claim 1 .

4. The gradient current collector is made of a metal foil. The battery of claim 1 .

5. The gradient current collector includes a metal foil and a conductive resin layer laminated on the metal foil. The battery of claim 1 .

6. The gradient current collector includes a support member having a thickness distribution and a metal foil covering the support member. The battery of claim 1 .

7. The gradient current collector further includes a conductive resin layer covering the metal foil. The battery of claim 6.

8. A plurality of the power generating elements stacked together; a plurality of counter electrode current collectors, at least one of which is the inclined current collector, stacked on the counter electrode layer; the electrode current collector has a plurality of electrode current collecting portions arranged along a stacking direction, and a folded portion that connects adjacent electrode current collecting portions among the plurality of electrode current collecting portions and is folded back in a first direction, the power generating element is laminated on both surfaces of each of the plurality of electrode current collecting portions, the plurality of counter electrode current collectors are arranged to sandwich the plurality of electrode current collectors, respectively, via the power generating elements stacked on both surfaces of the electrode current collectors. The battery of any one of claims 1 to 7.

9. In each of the plurality of power-generating elements, the directions in which the thickness of the power-generating element is reduced due to the inclination of the second main surface with respect to the first main surface are the same. The battery of claim 8.

10. Each of the plurality of counter electrode current collectors is the inclined current collector.

10. The battery of claim 9.

11. the plurality of counter electrode current collectors include, as the inclined current collectors, a first inclined current collector positioned between the power-generating elements stacked on adjacent electrode current collectors among the plurality of electrode current collectors and facing each other, and a second inclined current collector positioned at an end of the battery in the stacking direction, a difference between the maximum thickness and the minimum thickness of the inclined structure portion of the second inclined current collector is smaller than a difference between the maximum thickness and the minimum thickness of the inclined structure portion of the first inclined current collector; The battery of claim 10.

12. the battery further includes a connection member that covers an end surface of each of the plurality of power-generating elements in a second direction intersecting the first direction and is connected to one end of each of the plurality of counter electrode current collectors. The battery of claim 8.

13. The plurality of power generating elements include a first power generating element and a second power generating element that have different directions in which their thicknesses decrease due to the second main surface being inclined with respect to the first main surface. The battery of claim 8.

14. In each of the plurality of power-generating elements, a direction in which the thickness of the power-generating element is reduced due to the inclination of the second main surface with respect to the first main surface intersects with the first direction. The battery of claim 8.

15. The electrode layer is a negative electrode layer. The counter electrode layer is a positive electrode layer. The battery of claim 8.

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