Battery and method for producing same

Abstract

A battery according to the present disclosure comprises a unit cell that includes an electrode current collector, an electrode active material layer, a solid electrolyte layer, a counter electrode active material layer, and a counter electrode current collector in this order. In a plan view of the counter electrode current collector, at least one of a plurality of corner parts of the counter electrode active material layer is provided with a non-covered region that is not covered by the counter electrode current collector, and among a plurality of corner parts of the counter electrode current collector, a corner part that is provided with the non-covered region is provided with a first round part which has an R-chamfered shape.

Description

Battery and manufacturing method thereof

[0001] The present disclosure relates to batteries and methods for manufacturing the same.

[0002] Patent Document 1 describes a battery in which an electrode current collector, an electrode active material layer, a solid electrolyte layer, a counter electrode active material layer, and a counter electrode current collector are stacked.

[0003] Patent Document 2 describes a battery in which an electrode current collector, an electrode active material layer, a solid electrolyte layer, a counter electrode active material layer, and a counter electrode current collector are stacked. In the battery described in Patent Document 2, non-facing portions are provided at the ends of the electrode active material layer and the solid electrolyte layer, respectively.

[0004] Patent Document 3 describes a battery in which an electrode current collector, an electrode active material layer, a solid electrolyte layer, a counter electrode active material layer, and a counter electrode current collector are stacked. In the battery described in Patent Document 3, steps are provided in the electrode active material layer and the counter electrode active material layer, and an insulating layer is disposed on the counter electrode current collector.

[0005] JP 2019-140079 A JP 2020-129519 A JP 2022-104137 A

[0006] In the prior art, there is a need for improved battery reliability. Therefore, an object of the present disclosure is to provide a highly reliable battery and a method for manufacturing the same.

[0007] A battery according to one aspect of the present disclosure includes a unit cell including, in this order, an electrode current collector, an electrode active material layer, a solid electrolyte layer, a counter electrode active material layer, and a counter electrode current collector, wherein, in a plan view of the counter electrode current collector, at least one of a plurality of corners of the counter electrode active material layer is provided with an uncovered region that is not covered by the counter electrode current collector, and one of the plurality of corners of the counter electrode current collector where the uncovered region is provided is provided with a first rounded portion having an R-chamfered shape.

[0008] A method for manufacturing a battery according to one aspect of the present disclosure includes: preparing a laminate including, in this order, an electrode current collector, an electrode active material layer, a solid electrolyte layer, and a counter electrode active material layer; and disposing a counter electrode current collector on the counter electrode active material layer, wherein, in a plan view of the counter electrode current collector, at least one of a plurality of corners of the counter electrode active material layer is provided with an uncovered region that is not covered by the counter electrode current collector, and one of the plurality of corners of the counter electrode current collector where the uncovered region is provided is provided with a first rounded portion having an R-chamfered shape.

[0009] According to the present disclosure, a highly reliable battery and a method for manufacturing the same can be provided.

[0010] FIG. 1 is a side view of a battery according to embodiment 1. FIG. 2 is a top view of a battery according to embodiment 1. FIG. 3 is a top view of a battery according to modification 1 of embodiment 1. FIG. 4 is a top view showing an enlarged portion of the battery according to modification 1 of embodiment 1. FIG. 5 is a top view of a battery according to modification 2 of embodiment 1. FIG. 6 is a side view of a battery according to modification 3 of embodiment 1. FIG. 7A is a flowchart showing a method for manufacturing a battery according to embodiment 1 and each of its modifications. FIG. 7B is a flowchart showing a method for manufacturing a battery according to modification 3 of embodiment 1. FIG. 7C is a flowchart showing another example of a method for manufacturing a battery according to embodiment 1 and each of its modifications. FIG. 8 is a top view of a battery according to embodiment 2. FIG. 9 is a cross-sectional view of a battery according to embodiment 2. FIG. 10 is a side view of a battery according to embodiment 3. FIG. 11 is a flowchart showing a method for manufacturing a battery according to embodiment 3.

[0011] (Background of the Invention) In a battery including a unit cell including an electrode current collector, an electrode active material layer, a solid electrolyte layer, a counter electrode active material layer, and a counter electrode current collector in this order, a short circuit is likely to occur due to contact between an end of the electrode active material layer and the counter electrode active material layer or the counter electrode current collector, or between an end of the counter electrode active material layer and the electrode active material layer or the electrode current collector. In particular, when stacking counter electrode current collectors, misalignment of the counter electrode current collectors at the corners of the unit cells tends to cause a short circuit at the end faces.

[0012] In this way, the inventors focused on the problem that battery reliability is easily reduced due to short circuits occurring at the corners of unit cells, and achieved an embodiment of a battery that can suppress short circuits at the corners of unit cells.

[0013] Furthermore, when stacking counter electrode current collectors, short circuits are likely to occur at the edge of the unit cell due to misalignment of the counter electrode current collectors, not only at the corners of the unit cells but also at the sides of the unit cells. Furthermore, when stacking multiple unit cells, misalignment of the stacked unit cells increases the likelihood of short circuits at the edge. Furthermore, if the electrode active material layer or the counter electrode active material layer is exposed at the periphery of the unit cell, a short circuit is likely to occur due to the active material falling off. Thus, the present inventors further focused on other factors that cause short circuits in unit cells and have achieved an embodiment of a more reliable battery.

[0014] (Summary of the Present Disclosure) As an overview of the present disclosure, an example of a battery according to the present disclosure will be described below.

[0015] A battery according to a first aspect of the present disclosure includes a unit cell including, in this order, an electrode current collector, an electrode active material layer, a solid electrolyte layer, a counter electrode active material layer, and a counter electrode current collector, wherein, in a plan view of the counter electrode current collector, at least one of a plurality of corners of the counter electrode active material layer is provided with an uncovered region that is not covered by the counter electrode current collector, and one of the plurality of corners of the counter electrode current collector where the uncovered region is provided is provided with a first rounded portion having an R-chamfered shape.

[0016] This makes it difficult for the counter electrode current collector to protrude outside the counter electrode active material layer even if the counter electrode current collector is misaligned at the corner of the unit cell. As a result, short circuits caused by contact between the counter electrode current collector and the electrode active material layer or the electrode current collector are less likely to occur. This improves the reliability of the battery.

[0017] A battery according to a second aspect of the present disclosure is the battery according to the first aspect, wherein a second rounded portion having an R-chamfered shape is provided at a corner where the uncovered region is provided, among the plurality of corners of the counter electrode active material layer.

[0018] This eliminates corners in the counter electrode active material layer, making it difficult for the active material to fall off, and therefore, short circuits caused by the falling off of the active material are less likely to occur, further improving the reliability of the battery.

[0019] Furthermore, a battery according to a third aspect of the present disclosure is the battery according to the second aspect, wherein when the radius of the R-chamfered shape of the first rounded portion is R1 and the radius of the R-chamfered shape of the second rounded portion is R2, R2 < R1 is satisfied.

[0020] This can prevent the counter electrode current collector from protruding outside the counter electrode active material layer, making short circuits less likely to occur, thereby further improving the reliability of the battery.

[0021] A battery according to a fourth aspect of the present disclosure is the battery according to any one of the first to third aspects, wherein the uncovered region is further provided on at least one of a plurality of side portions of the counter electrode active material layer.

[0022] This makes it less likely that the counter electrode current collector will protrude outside the counter electrode active material layer even at the edges, further reducing the likelihood of short circuits occurring and further improving the reliability of the battery.

[0023] A battery according to a fifth aspect of the present disclosure is the battery according to any one of the first to fourth aspects, wherein the electrode active material layer includes a negative electrode active material, and the counter electrode active material layer includes a positive electrode active material. That is, the electrode current collector and the electrode active material layer may be a negative electrode current collector and a negative electrode active material layer, respectively, and the counter electrode current collector and the counter electrode active material layer may be a positive electrode current collector and a positive electrode active material layer, respectively.

[0024] As a result, the area of ​​the positive electrode active material layer that is covered by the positive electrode current collector and functions as a positive electrode is smaller than that of the negative electrode active material layer. Therefore, the capacity of the negative electrode active material layer tends to be larger than that of the positive electrode active material layer. This suppresses the deposition of metal derived from metal ions that are not incorporated into the negative electrode active material layer, thereby further improving the reliability of the battery.

[0025] Furthermore, a battery according to a sixth aspect of the present disclosure is the battery according to any one of the first to fifth aspects, wherein the unit cell includes two of each of the electrode active material layer, the solid electrolyte layer, the counter electrode active material layer, and the counter electrode current collector, the electrode current collector having a first main surface and a second main surface opposite to the first main surface, one of the two electrode active material layers, one of the two solid electrolyte layers, one of the two counter electrode active material layers, and one of the two counter electrode current collectors being stacked in this order on the first main surface, and the other of the two electrode active material layers, the other of the two solid electrolyte layers, the other of the two counter electrode active material layers, and the other of the two counter electrode current collectors being stacked in this order on the second main surface.

[0026] This allows currents from two electrode active material layers to be extracted from one electrode current collector, thereby increasing the volumetric energy density of the battery.

[0027] A battery according to a seventh aspect of the present disclosure is the battery according to any one of the first to sixth aspects, further comprising an insulating layer covering a periphery of the unit cell.

[0028] As a result, at least one portion of the electrode current collector, electrode active material layer, counter electrode active material layer, and counter electrode current collector exposed at the periphery of the unit cell is covered with an insulating layer, which significantly reduces the possibility of short circuits caused by contact between electrodes of opposite polarity, thereby further improving the reliability of the battery.

[0029] A battery according to an eighth aspect of the present disclosure is the battery according to any one of the first to sixth aspects, including a plurality of the unit cells, the plurality of unit cells being stacked.

[0030] This allows for stacking unit cells that are less likely to short-circuit at corners, resulting in a highly reliable stacked battery.

[0031] Furthermore, a method for manufacturing a battery according to a ninth aspect of the present disclosure includes the steps of: preparing a laminate including an electrode current collector, an electrode active material layer, a solid electrolyte layer, and a counter electrode active material layer in this order; and arranging a counter electrode current collector on the counter electrode active material layer, wherein, in a plan view of the counter electrode current collector, at least one of a plurality of corners of the counter electrode active material layer is provided with an uncovered region that is not covered by the counter electrode current collector, and one of the plurality of corners of the counter electrode current collector where the uncovered region is provided is provided with a first rounded portion having an R-chamfered shape.

[0032] This makes it difficult for the counter electrode current collector to protrude outside the counter electrode active material layer even if the counter electrode current collector is misaligned at the corner of the unit cell. As a result, short circuits caused by contact between the counter electrode current collector and the electrode active material layer or the electrode current collector are less likely to occur. This makes it possible to manufacture a highly reliable battery.

[0033] A battery manufacturing method according to a tenth aspect of the present disclosure is the battery manufacturing method according to the ninth aspect, further including the step of forming the first rounded portion on the counter electrode current collector, wherein in the placing step, the counter electrode current collector provided with the first rounded portion is placed so as not to cover at least a part of at least one of a plurality of corners of the counter electrode active material layer, thereby forming the uncovered region in the counter electrode active material layer.

[0034] This allows the counter electrode current collector to be rounded in advance before being placed on the counter electrode active material layer, making it easier to form the rounded portion in the desired shape. Since it is easier to form the rounded portion as designed, short circuits are less likely to occur. This allows for the production of a highly reliable battery.

[0035] A method for manufacturing a battery according to an eleventh aspect of the present disclosure is the method for manufacturing a battery according to the tenth aspect, further including the step of forming a second rounded portion having an R-chamfered shape in at least one of the plurality of corners of the counter electrode active material layer.

[0036] This eliminates corners in the counter electrode active material layer, making it difficult for the active material to fall off, and therefore, short circuits caused by the falling off of the active material are less likely to occur, making it possible to manufacture a highly reliable battery.

[0037] A battery manufacturing method according to a twelfth aspect of the present disclosure is the battery manufacturing method according to the eleventh aspect, wherein in the placing step, the counter electrode current collector provided with the first rounded portion is placed so as not to cover at least a part of the corner provided with the second rounded portion, thereby forming the uncovered region in the counter electrode active material layer.

[0038] This makes it easier to form an uncovered area as designed at the corner where the second rounded portion is provided, making it less likely that a short circuit will occur, thereby enabling the manufacture of a highly reliable battery.

[0039] Furthermore, a method for manufacturing a battery according to a thirteenth aspect of the present disclosure is a method for manufacturing a battery according to the eleventh or twelfth aspect, wherein, when the radius of the R-chamfered shape of the first rounded portion is R1 and the radius of the R-chamfered shape of the second rounded portion is R2, R2 < R1 is satisfied.

[0040] This can prevent the counter electrode current collector from protruding outside the counter electrode active material layer, making it less likely that a short circuit will occur, thereby enabling the manufacture of a highly reliable battery.

[0041] A battery manufacturing method according to a fourteenth aspect of the present disclosure is the battery manufacturing method according to any one of the ninth to thirteenth aspects, wherein in the placing step, the counter electrode current collector is placed so as not to cover at least a portion of at least one of a plurality of side portions of the counter electrode active material layer.

[0042] This makes it difficult for the counter electrode current collector to protrude outside the counter electrode active material layer even at the edges, making it even more difficult for short circuits to occur and enabling the production of a highly reliable battery.

[0043] A method for manufacturing a battery according to a fifteenth aspect of the present disclosure is the method for manufacturing a battery according to any one of the ninth to fourteenth aspects, wherein the electrode active material layer contains a negative electrode active material, and the counter electrode active material layer contains a positive electrode active material.

[0044] As a result, the area of ​​the positive electrode active material layer that is covered by the positive electrode current collector and functions as a positive electrode is smaller than that of the negative electrode active material layer. Therefore, the capacity of the negative electrode active material layer tends to be larger than that of the positive electrode active material layer. This suppresses the deposition of metal derived from metal ions that are not incorporated into the negative electrode active material layer, allowing for the production of a highly reliable battery.

[0045] A battery manufacturing method according to a sixteenth aspect of the present disclosure is the battery manufacturing method according to any one of the ninth to fifteenth aspects, in which the preparing step includes preparing the electrode current collector having a first main surface and a second main surface opposite the first main surface, and stacking the electrode active material layer, the solid electrolyte layer, and the counter electrode active material layer in this order on each of the first main surface and the second main surface, and the arranging step includes preparing two counter electrode current collectors and arranging the two prepared counter electrode current collectors on main surfaces of the two counter electrode active material layers opposite the solid electrolyte layer.

[0046] This allows currents from two electrode active material layers to be extracted from one electrode current collector, making it possible to manufacture a battery with a high volumetric energy density.

[0047] In addition, a battery manufacturing method according to a seventeenth aspect of the present disclosure is a battery manufacturing method according to any one of the ninth to sixteenth aspects, further including a step of covering the peripheral portion of the laminate with an insulating layer.

[0048] As a result, at least one portion of the electrode current collector, electrode active material layer, counter electrode active material layer, and counter electrode current collector that are exposed at the peripheral edge of the laminate is covered with an insulating layer, which significantly reduces the possibility of short circuits caused by contact between electrodes of opposite polarity, thereby enabling the production of a highly reliable battery.

[0049] A battery manufacturing method according to an eighteenth aspect of the present disclosure is the battery manufacturing method according to any one of the ninth to seventeenth aspects, further including the step of stacking a plurality of the laminates.

[0050] This allows for stacking of stacked bodies that are less likely to short-circuit at corners, making it possible to manufacture a highly reliable stacked battery.

[0051] Furthermore, a battery manufacturing method according to a nineteenth aspect of the present disclosure is the battery manufacturing method according to any one of the ninth to eighteenth aspects, wherein the step of preparing the laminate includes preparing a plurality of the laminates; the step of arranging the counter electrode current collector includes preparing a plurality of the counter electrode current collectors; arranging the plurality of counter electrode current collectors such that the counter electrode current collectors and the laminates are alternately arranged in stacking order; and further including, after the step of arranging the plurality of counter electrode current collectors, a step of collectively pressing the plurality of laminates.

[0052] This allows a plurality of stacks to be pressed together, making it possible to manufacture a highly reliable stack battery using a simple manufacturing method.

[0053] Furthermore, a battery manufacturing method according to a twentieth aspect of the present disclosure is the battery manufacturing method according to any one of the ninth to nineteenth aspects, further including, before the step of arranging the counter electrode current collector, the step of pressing the stack at a first pressure, and then pressing the stack at a second pressure lower than the first pressure.

[0054] This improves the flatness of the laminate, thereby improving the accuracy of the placement of the counter electrode current collector and the accuracy of the dimensions and placement of the uncovered region, thereby enabling the manufacture of a highly reliable battery.

[0055] Hereinafter, the embodiments will be specifically described with reference to the drawings.

[0056] 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.

[0057] 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.

[0058] Furthermore, in this specification, terms indicating the relationship between elements, such as parallel or perpendicular, terms indicating the shape of elements, such as rectangular or circular, 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.

[0059] In this specification and the drawings, the x-axis, y-axis, and z-axis represent the three axes of a three-dimensional Cartesian coordinate system. The x-axis and y-axis are directions parallel to the main surface of the electrode current collector, and the z-axis is a direction perpendicular to the main surface of the electrode current collector. When the shape of the battery in a plan view is rectangular, the x-axis and y-axis are directions parallel to a first side of the rectangle and a second side perpendicular to the first side, respectively. The z-axis is the stacking direction of the multiple unit cells included in the battery. In this specification, the "stacking direction" coincides with the direction normal to the main surfaces of the current collector and the active material layer. In this specification, the term "plan view" refers to a view perpendicular to the main surface of the electrode current collector, unless otherwise specified.

[0060] 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."

[0061] In this specification, the corners and sides of a current collector are each parts of the current collector defined based on the shape of the current collector in a planar view. When the shape of the current collector in a planar view is polygonal, a corner is a portion including one vertex of the polygon, and a side is a portion including at least part of one side of the polygon. In other words, when the shape of the current collector in a planar view is an n-sided polygon (n is a natural number greater than or equal to 3), the current collector has n corners and n sides.

[0062] For example, if two sides extending in two directions from a single vertex are defined as a first side and a second side, a corner including the vertex can be considered to be a triangular region with three vertices: the vertex, a position on the first side from the vertex at a distance of 10% of the length of the first side, and a position on the second side from the vertex at a distance of 10% of the length of the second side. If a corner has a rounded portion with a chamfered shape, the intersection of the extensions of the two sides corresponding to the corner can be considered to be the vertex. Furthermore, a side can be considered to be a band-shaped region that includes the corresponding side and extends along the side, excluding the two corners located at both ends of the side. The width of a side is, for example, a length that does not overlap with other sides.

[0063] The term "polygon" refers to any shape that can be considered substantially polygonal, and at least some of the sides of the polygon may be curved. For example, the deviation of a curved side from a straight line connecting the two vertices at both ends of the curved side may be 10% or less of the length of the side.

[0064] 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 for the purpose of avoiding confusion and distinguishing between components of the same type.

[0065] First Embodiment [1. Configuration] First, the configuration of a battery according to a first embodiment will be described with reference to FIGS. 1 and 2. FIG.

[0066] FIG. 1 is a side view of a battery 1 according to this embodiment. FIG. 2 is a top view of the battery 1 according to this embodiment. FIG. 1 shows the side view of the battery 1 when viewed from the negative side of the y-axis. FIG. 2 shows the plan view of the battery 1 when viewed from the positive side of the z-axis. In each of the drawings including FIG. 1 and FIG. 2 (except FIG. 4), each component is shaded to make it easier to distinguish between them. Components of the same type are shaded the same way.

[0067] As shown in FIGS. 1 and 2 , a battery 1 according to the present embodiment includes a unit cell 100 including, in this order, an electrode current collector 10, an electrode active material layer 20, a solid electrolyte layer 30, a counter electrode active material layer 40, and a counter electrode current collector 50. In the unit cell 100, the electrode current collector 10, the electrode active material layer 20, the solid electrolyte layer 30, the counter electrode active material layer 40, and the counter electrode current collector 50 are stacked in this order along the z-axis. In this embodiment, as shown in FIG. 2 , each of a plurality of corners 51, 52, 53, and 54 of the counter electrode current collector 50 is provided with a rounded chamfered portion 51r, 52r, 53r, and 54r, respectively. Also, as shown in FIG. 1 , the battery 1 is formed from only one unit cell 100. The battery 1 is, for example, an all-solid-state battery.

[0068] The planar shape of the battery 1 and the unit cell 100 is rectangular as shown in FIG. 1 . That is, the general shape of the battery 1 and the unit cell 100 is a flattened rectangular parallelepiped. Here, "flat" means that the thickness is shorter than each side or the maximum width of the main surface. Each side or the maximum width of the main surface of the battery 1 and the unit cell 100 is, for example, 10 mm or more and 500 mm or less. The planar shape of the battery 1 and the unit cell 100 may be another polygonal shape, such as a square, hexagon, or octagon. Alternatively, the planar shape of the battery 1 and the unit cell 100 may be a combination of a polygonal shape and a circular or elliptical shape. Note that in the drawings related to this specification, the thickness of each layer is exaggerated to make the layer structure of the unit cell 100 easier to understand.

[0069] The side surface of the unit cell 100 is composed of the side surfaces of the electrode current collector 10, the electrode active material layer 20, the solid electrolyte layer 30, the counter electrode active material layer 40, and the counter electrode current collector 50. For example, at least a portion of the side surface of the unit cell 100 is a flat plane. In this plane, at least the side surfaces of the electrode current collector 10, the electrode active material layer 20, the solid electrolyte layer 30, and the counter electrode active material layer 40 are flush with one another and lie on the same flat plane. In other words, at each end of the unit cell 100 in the positive x-axis direction, the negative x-axis direction, the positive y-axis direction, and the negative y-axis direction, the side surfaces of the electrode current collector 10, the electrode active material layer 20, the solid electrolyte layer 30, and the counter electrode active material layer 40 are flush with one another. Furthermore, at each end of the unit cell 100 in the positive x-axis direction, the negative x-axis direction, the positive y-axis direction, and the negative y-axis direction, the side surfaces of the electrode current collector 10, the electrode active material layer 20, the solid electrolyte layer 30, the counter electrode active material layer 40, and the counter electrode current collector 50 may be flush. This eliminates steps and irregularities on the side surfaces of the layers at the end of the unit cell 100, preventing the formation of spaces that do not function as a battery due to irregularities, thereby improving the volumetric energy density of the battery 1. Furthermore, the side surfaces of the layers can be flush by cutting the layers together, for example, which facilitates the manufacture of the battery 1.

[0070] The side surface of the unit cell 100 is, for example, a cut surface. Specifically, it is a surface formed by cutting with a blade such as a cutter or a punching die, and is, for example, a surface having a cut mark such as a fine groove. By using a cut surface, the side surfaces of the layers of the unit cell 100 can be easily made flush. The cut mark may be smoothed by polishing or the like. The shape of the cut surface is not limited.

[0071] The unit cell 100 has one each of an electrode current collector 10, an electrode active material layer 20, a solid electrolyte layer 30, a counter electrode active material layer 40, and a counter electrode current collector 50. In a plan view, the electrode current collector 10, the electrode active material layer 20, the solid electrolyte layer 30, the counter electrode active material layer 40, and the counter electrode current collector 50 overlap each other.

[0072] The electrode current collector 10 is in contact with the electrode active material layer 20 at one main surface 10a. The main surface 10a is an example of a first main surface of the electrode current collector 10. As shown in Fig. 1 , the electrode current collector 10 has main surfaces 10a and 10b. The main surface 10b is an example of a second main surface of the electrode current collector 10 that is opposite to the first main surface.

[0073] The thickness of the electrode current collector 10 is, for example, 5 μm or more and 100 μm or less. In this specification, the thickness of the current collector and each layer is the length in the stacking direction, and unless otherwise specified, is the average value of the entire thickness. The average thickness can be considered to be the average value of thickness measurements taken at multiple arbitrary locations within an area excluding corners and sides. The measurement locations are, for example, three locations.

[0074] Known materials can be used as the material for the electrode current collector 10. For example, a foil, plate, or mesh-like body made of copper, aluminum, nickel, iron, stainless steel, platinum, gold, or an alloy of two or more of these materials can be used for the electrode current collector 10. In addition to the foil, plate, or mesh-like body, the electrode current collector 10 may also include a connection layer that is a layer containing a conductive material and is provided in a portion that contacts the electrode active material layer 20.

[0075] The counter electrode current collector 50 is disposed on the side of the counter electrode active material layer 40 opposite to the solid electrolyte layer 30 side. The counter electrode current collector 50 is in contact with the main surface 40a of the counter electrode active material layer 40. The thickness of the counter electrode current collector 50 is, for example, 5 μm or more and 100 μm or less.

[0076] Known materials can be used as the material of the counter electrode current collector 50. For example, a foil, plate, or mesh-like body made of copper, aluminum, nickel, iron, stainless steel, platinum, gold, or an alloy of two or more of these can be used for the counter electrode current collector 50. Note that, in addition to the foil, plate, or mesh-like body, the counter electrode current collector 50 may also include a connection layer that is a layer containing a conductive material and is provided in a portion that contacts the counter electrode active material layer 40.

[0077] The electrode active material layer 20 is disposed on one main surface 10a of the electrode current collector 10. The surface of the electrode active material layer 20 opposite to the electrode current collector 10 side is in contact with the solid electrolyte layer 30. The electrode active material layer 20 and the counter electrode active material layer 40 face each other with the solid electrolyte layer 30 sandwiched between them. The thickness of the electrode active material layer 20 is, for example, 5 μm or more and 300 μm or less. Materials used for the electrode active material layer 20 will be described later.

[0078] The solid electrolyte layer 30 is disposed on the side of the electrode active material layer 20 opposite to the electrode current collector 10 side. The solid electrolyte layer 30 is located between the electrode active material layer 20 and the counter electrode active material layer 40, and is in contact with the electrode active material layer 20 and the counter electrode active material layer 40. The thickness of the solid electrolyte layer 30 is, for example, 5 μm or more and 150 μm or less. The material used for the solid electrolyte layer 30 will be described later.

[0079] The counter electrode active material layer 40 is disposed on the side of the solid electrolyte layer 30 opposite to the electrode active material layer 20. The counter electrode active material layer 40 is laminated on the solid electrolyte layer 30 and faces the electrode active material layer 20. The thickness of the counter electrode active material layer 40 is, for example, 5 μm or more and 300 μm or less. The material used for the counter electrode active material layer 40 will be described later.

[0080] Here, the materials used for the solid electrolyte layer 30, the electrode active material layer 20, and the counter electrode active material layer 40 will be described.

[0081] The solid electrolyte layer 30 is an example of an electrolyte layer containing an electrolyte material. The solid electrolyte layer 30 contains at least a solid electrolyte as the electrolyte material, and may contain a binder material as necessary. The solid electrolyte layer 30 may contain a solid electrolyte having lithium ion conductivity. The electrolyte material contained in the solid electrolyte layer 30 is entirely solid electrolyte, except for unavoidable impurities, for example. Note that the electrolyte material used in the solid electrolyte layer 30 may further contain a nonaqueous electrolyte solution, a gel electrolyte solution, or an ionic liquid, as long as it contains a solid electrolyte as a main component. The following describes a case where the electrolyte material contained in the solid electrolyte layer 30 is entirely solid electrolyte.

[0082] As the solid electrolyte, known materials such as lithium ion conductors, sodium ion conductors, magnesium ion conductors, etc. can be used. As the solid electrolyte, for example, a solid electrolyte material such as a sulfide solid electrolyte, a halide solid electrolyte, an oxide solid electrolyte, a polymer solid electrolyte, or a complex hydride solid electrolyte can be used.

[0083] As the sulfide solid electrolyte, in the case of a material capable of conducting lithium ions, for example, lithium sulfide (Li ２ S) and diphosphorus pentasulfide (P ２ S ５ ) is used. As the sulfide solid electrolyte, Li ２ S-SiS ２ , Li ２ S-B ２ S ３ or Li ２ S-GeS ２ Sulfides such as Li may be used as an additive to the sulfides. ３ N, LiCl, LiBr, Li ３ P.O. ４ and Li ４ SiO ４ A sulfide to which at least one of the following is added may be used.

[0084] As the oxide solid electrolyte, in the case of a material that can conduct lithium ions, for example, Li ７ La ３ Zr ２ O １２ (LLZ), Li １．３ Al ０．３ Ti １．７ (P.O. ４ ) ３ (LATP) or (La,Li)TiO ３ (LLTO) and the like are used.

[0085] As the binder material, for example, elastomers such as styrene-based elastomers are used, and organic compounds such as polyvinylidene fluoride, acrylic resin, or cellulose resin may also be used.

[0086] One of the electrode active material layer 20 and the counter electrode active material layer 40 is a positive electrode active material layer, and the other is a negative electrode active material layer. In this embodiment, the electrode active material layer 20 is a negative electrode active material layer containing a negative electrode active material. The counter electrode active material layer 40 is a positive electrode active material layer containing a positive electrode active material. The electrode current collector 10 is a negative electrode current collector, and the counter electrode current collector 50 is a positive electrode current collector. Note that the electrode active material layer 20 and the electrode current collector 10 may be a positive electrode active material layer and a positive electrode current collector, and the counter electrode active material layer 40 and the counter electrode current collector 50 may be a negative electrode active material and a negative electrode current collector.

[0087] The positive electrode active material layer contains at least a positive electrode active material, and may contain at least one of an electrolyte material such as a solid electrolyte, a conductive additive, and a binder material, as necessary.

[0088] As the positive electrode active material, known materials capable of occluding and releasing (inserting and desorbing, or dissolving and depositing) lithium ions, sodium ions, magnesium ions, etc. can be used. As the positive electrode active material, materials capable of extracting and inserting lithium ions include, for example, transition metal oxides, transition metal fluorides, polyanion materials, fluorinated polyanion materials, transition metal sulfides, transition metal oxysulfides, transition metal oxynitrides, sulfur, and lithium-containing compounds thereof. Examples of lithium-containing transition metal oxides include Li(NiCoAl)O ２ , Li(NiCoMn)O ２ , LiCoO ２ Li(NiCoAl)O ２ means that Ni, Co, and Al are contained in any ratio. Li(NiCoMn)O ２ means that Ni, Co and Mn are contained in any ratio.

[0089] The solid electrolyte may be any of the solid electrolyte materials exemplified above. The conductive material used in the conductive additive may be, for example, acetylene black, carbon black, graphite, carbon fiber, vapor-grown carbon, or conductive carbon such as carbon nanotubes. The binder may be any of the binder materials exemplified above.

[0090] The negative electrode active material layer contains at least a negative electrode active material, and may contain at least one of an electrolyte material such as a solid electrolyte, a conductive additive, and a binder material, as necessary.

[0091] The negative electrode active material may be a known material capable of occluding and releasing (inserting and desorbing, or dissolving and precipitating) lithium ions, sodium ions, magnesium ions, etc. In the case of a material capable of extracting and inserting lithium ions, for example, a carbon material such as natural graphite, artificial graphite, graphite carbon fiber, or resin-baked carbon, metallic lithium, a lithium alloy, silicon (Si), tin (Sn), a silicon compound, a tin compound, or an oxide of lithium and a transition metal element may be used as the negative electrode active material.

[0092] The solid electrolyte may be any of the solid electrolyte materials exemplified above. The conductive additive may be any of the conductive materials exemplified above. The binder material may be any of the binder materials exemplified above.

[0093] Next, the structure of the corners of the unit cell 100 will be described.

[0094] As shown in FIGS. 1 and 2 , in the unit cell 100, R-chamfered portions 51r, 52r, 53r, and 54r are provided at four corners 51, 52, 53, and 54 of the counter electrode current collector 50, respectively. The R-chamfered portions 51r, 52r, 53r, and 54r are each an example of a first rounded portion having a R-chamfered shape. For example, the R-chamfered portion 51r is a portion that smoothly connects two end faces of the counter electrode current collector 50 corresponding to two sides that sandwich the corner 51 in a plan view. Specifically, the R-chamfered portion 51r has the same shape as the side surface of a cylinder. The same is true for the R-chamfered portions 52r, 53r, and 54r.

[0095] The R-chamfered shape refers to a shape that can be formed by R-chamfering, as an example, and the method for forming the rounded portion having the R-chamfered shape is not limited to R-chamfering. The R-chamfered shape is a shape in which, in a plan view of the counter electrode current collector 50, the outline of at least a portion of the corner of the counter electrode current collector 50 is an arc, but is not limited to this. For example, the R-chamfered shape may be a shape in which, in a plan view of the counter electrode current collector 50, the outline of at least a portion of the corner of the counter electrode current collector 50 is an elliptical arc, or may be a curved convex shape similar to an arc or an elliptical arc (for example, a parabola).

[0096] Furthermore, corners 41, 42, 43, and 44 of the counter electrode active material layer 40 are provided with uncovered regions 41 a, 42 a, 43 a, and 44 a that are not covered by the counter electrode current collector 50, respectively. The uncovered regions 41 a, 42 a, 43 a, and 44 a are all part of the main surface 40 a of the counter electrode active material layer 40. The main surface 40 a is one of two main surfaces of the counter electrode active material layer 40, and is the main surface on the side where the counter electrode current collector 50 is provided.

[0097] In addition, assuming that R-chamfered portions 51r, 52r, 53r, and 54r are not provided, in this embodiment, the four vertices of counter electrode current collector 50 corresponding to each of four corners 51, 52, 53, and 54 are located at positions that overlap with the four vertices of counter electrode active material layer 40 in a planar view. That is, uncovered regions 41a, 42a, 43a, and 44a are exposed portions that are not covered by counter electrode current collector 50 due to R-chamfered portions 51r, 52r, 53r, and 54r being provided on counter electrode current collector 50, respectively. Each of uncovered regions 41a, 42a, 43a, and 44a has a shape obtained by removing a quadrant inscribed in the square from the square in a planar view. That is, each of uncovered regions 41a, 42a, 43a, and 44a has a shape obtained by removing a quadrant inscribed in the square from the square in a planar view. That is, each of uncovered regions 41a, 42a, 43a, and 44a has a shape of a right-angled isosceles triangle whose hypotenuse is an arc.

[0098] This makes it difficult for the counter electrode current collector 50 to protrude outside the counter electrode active material layer 40, even if misalignment occurs at the four corners of the unit cell 100. As a result, a short circuit caused by contact between the counter electrode current collector 50 and the electrode active material layer 20 or the electrode current collector 10 is unlikely to occur. This makes it possible to improve the reliability of the battery 1.

[0099] The radius (also referred to as the R dimension) of each of the R-chamfered portions 51r, 52r, 53r, and 54r is, for example, 0.05 mm or more and 10 mm or less. Alternatively, the radius of each of the R-chamfered portions 51r, 52r, 53r, and 54r may be 0.1 mm or more and 5 mm or less. The radius of each of the R-chamfered portions 51r, 52r, 53r, and 54r may be 0.3 mm or more and 3 mm or less, or 0.5 mm or more and 1 mm or less. The larger the radius, the less likely the counter electrode current collector 50 is to protrude outside the counter electrode active material layer 40, which is effective in suppressing short circuits. The smaller the radius, the larger the area functioning as a counter electrode, thereby increasing the energy density of the battery 1. The R-chamfered portions 51r, 52r, 53r, and 54r have the same shape and size, but this is not limited thereto. At least one of the R-chamfered portions 51r, 52r, 53r, and 54r may be different from the other R-chamfered portions in at least one of the shape and size.

[0100] Furthermore, at each of corners 41, 42, 43, and 44 of counter electrode active material layer 40, the shortest distance from the respective vertices to counter electrode current collector 50 is, for example, 0.01 mm or more and 5 mm or less. This makes it possible to prevent counter electrode current collector 50 from protruding outside counter electrode active material layer 40 without significantly impairing the region of counter electrode active material layer 40 that is covered by counter electrode current collector 50 and functions as a counter electrode.

[0101] 1 and 2 , R-chamfered portions 51r, 52r, 53r, and 54r are provided at all corners 51, 52, 53, and 54 of counter electrode current collector 50, respectively; however, this is not limited thereto. For example, an R-chamfered portion may be provided at only one of four corners 51, 52, 53, and 54. Alternatively, an R-chamfered portion may be provided at only two or three of four corners 51, 52, 53, and 54. When R-chamfered portions are provided at only two corners, the two corners at which R-chamfered portions are provided may be two adjacent corners, such as corners 52 and 53, or may be two diagonally opposite corners, such as corners 51 and 53.

[0102] [2. Modifications] The following describes batteries according to modifications of the present embodiment. In the following description of the modifications, differences from the first embodiment and each modification will be mainly described, and descriptions of commonalities will be omitted or simplified.

[0103] [2-1. Modification 1] First, a battery according to Modification 1 of Embodiment 1 will be described. Fig. 3 is a top view of battery 2 according to this modification. Fig. 4 is a top view showing an enlarged portion of battery 2 according to this modification. Specifically, Fig. 4 shows an enlarged region including corner 51 of counter electrode current collector 50 and corner 41 of counter electrode active material layer 40.

[0104] Battery 2 according to this modification differs from Battery 1 in that, among the multiple corners 41, 42, 43, and 44 of the counter electrode active material layer 40, corners that have uncovered regions that are not covered by the counter electrode current collector 50 are provided with second rounded portions having an R-chamfered shape. Specifically, as shown in FIGS. 3 and 4 , in Battery 2, uncovered regions 41 a, 42 a, 43 a, and 44 a are provided at all corners 41, 42, 43, and 44 of the counter electrode active material layer 40, respectively. Therefore, in addition to R-chamfered portions 51 r, 52 r, 53 r, and 54 r provided in the counter electrode current collector 50, R-chamfered portions 41 r, 42 r, 43 r, and 44 r are also provided in the counter electrode active material layer 40.

[0105] Each of the R-chamfered portions 41r, 42r, 43r, and 44r is an example of a second rounded portion having an R-chamfered shape. For example, the R-chamfered portion 41r is a portion that smoothly connects two end faces of the counter electrode active material layer 40 that correspond to two sides sandwiching the corner portion 41 in a plan view. Specifically, the R-chamfered portion 41r has the same shape as the side surface of a cylinder. The same is true for the R-chamfered portions 42r, 43r, and 44r.

[0106] As shown in FIG. 4 , when the radius of the R-chamfered portion 51r at the corner 51 of the counter electrode current collector 50 is R1 and the radius of the R-chamfered portion 41r at the corner 41 of the counter electrode active material layer 40 is R2, the relationship R2<R1 is satisfied. As a result, even when the R-chamfered portion 41r is provided at the corner 41 of the counter electrode active material layer 40, an uncovered region 41a is provided on the counter electrode current collector 50. Similarly, the radius of the R-chamfered portion 52r is larger than the radius of the R-chamfered portion 42r. The radius of the R-chamfered portion 53r is larger than the radius of the R-chamfered portion 43r. The radius of the R-chamfered portion 54r is larger than the radius of the R-chamfered portion 44r.

[0107] As a result, the corners 41, 42, 43, and 44 of the counter electrode active material layer 40 are each rounded, making the layer 40 more resistant to external impacts and less likely to cause the active material to fall off. Also, the counter electrode current collector 50 can be prevented from protruding outside the counter electrode active material layer 40. This reduces the likelihood of short circuits, improving the reliability of the battery 2.

[0108] In the battery 2 according to this modification, the solid electrolyte layer 30, the electrode active material layer 20, and the electrode current collector 10 each have rounded chamfers equivalent to the rounded chamfers 41r, 42r, 43r, and 44r. That is, the rounded chamfers 41r, 42r, 43r, and 44r do not expose the solid electrolyte layer 30, the electrode active material layer 20, and the electrode current collector 10. The upper surface of the solid electrolyte layer 30 is completely covered by the counter electrode active material layer 40, and the upper surface of the electrode active material layer 20 is completely covered by the solid electrolyte layer 30. Since the active material is less likely to fall off at the corners of the electrode active material layer 20, short circuits caused by the falloff are less likely to occur, thereby improving the reliability of the battery 2. Furthermore, for example, the corners of the counter electrode active material layer 40, the solid electrolyte layer 30, the electrode active material layer 20, and the electrode current collector 10 can be formed by simultaneous processing, thereby simplifying the manufacturing process of the battery 2. The R-chamfered portion may not be provided on the solid electrolyte layer 30, the electrode active material layer 20, and the electrode current collector 10. That is, the upper surface of the solid electrolyte layer 30 may have a region that is not covered by the counter electrode active material layer 40.

[0109] 4 shows the center P1 of the R-chamfered shape (arc) of the R-chamfered portion 51r and the center P2 of the R-chamfered shape (arc) of the R-chamfered portion 41r. The center P2 is located at a position overlapping the counter electrode current collector 50 in a plan view. This increases the radius R2 of the R-chamfered portion 41r, thereby improving the effect of suppressing the detachment of active material at the corners 41 of the counter electrode active material layer 40. This reduces the likelihood of short circuits caused by detachment of active material, thereby improving the reliability of the battery 2.

[0110] Alternatively, the center P2 may be located on the arc of the R-chamfered portion 51r, and may be located at a position that does not overlap with the counter electrode current collector 50. This allows the uncovered region 41a to be larger, making it easier to suppress protrusion of the counter electrode current collector 50. As a result, short circuits caused by protrusion of the counter electrode current collector 50 are less likely to occur, and the reliability of the battery 2 can be improved.

[0111] 3, all corners 41, 42, 43, and 44 of the counter electrode active material layer 40 are provided with R-chamfered portions 41r, 42r, 43r, and 44r, respectively. However, this is not limited thereto. For example, an R-chamfered portion may be provided on only one of the four corners 41, 42, 43, and 44. Alternatively, an R-chamfered portion may be provided on only two or three of the four corners 41, 42, 43, and 44. When an R-chamfered portion is provided on only two corners, the two corners on which the R-chamfered portions are provided may be two adjacent corners, such as corners 42 and 43, or may be two diagonally opposite corners, such as corners 41 and 43. Of the four corners 41, 42, 43, and 44 of the counter electrode active material layer 40, corners on which uncovered regions are provided may not be provided with R-chamfered portions. Alternatively, a rounded chamfer may be provided at a corner that is not provided with an uncovered region, among the four corners 41, 42, 43, and 44 of the counter electrode active material layer 40. For example, the radius R1 of the rounded chamfer 51r of the counter electrode current collector 50 and the radius R2 of the rounded chamfer 41r of the counter electrode active material layer 40 may be the same.

[0112] [2-2. Modification 2] Next, a description will be given of a battery according to Modification 2 of Embodiment 1. Fig. 5 is a top view of a battery 3 according to this modification.

[0113] Battery 3 according to this modification differs from Battery 2 in that an uncovered region that is not covered by the counter electrode current collector 50 is further provided on at least one of a plurality of side portions of the counter electrode active material layer 40. Specifically, as shown in Fig. 5 , in battery 3, in addition to R-chamfered portions 51r, 52r, 53r, and 54r provided on the counter electrode current collector 50 and R-chamfered portions 41r, 42r, 43r, and 44r provided on the counter electrode active material layer 40, uncovered regions 45a and 46a that are not covered by the counter electrode current collector 50 are also provided on side portions 45 and 46 of the counter electrode active material layer 40.

[0114] The non-covered region 45a is located between the non-covered region 43a provided in the corner 43 and the non-covered region 44a provided in the corner 44, and is provided so as to be continuous with each other. The non-covered region 45a is a band-shaped region extending along one side corresponding to the side 45 of the counter electrode active material layer 40. The non-covered region 46a is located between the non-covered region 44a provided in the corner 44 and the non-covered region 41a provided in the corner 41, and is provided so as to be continuous with each other. The non-covered region 46a is a band-shaped region extending along one side corresponding to the side 46 of the counter electrode active material layer 40. That is, in this modification, the counter electrode active material layer 40 has one non-covered region that is continuous across the corner 43, the side 45, the corner 44, the side 46, and the corner 41.

[0115] This makes it less likely that the counter electrode current collector 50 will protrude outside the counter electrode active material layer 40 even at the side portions 45 and 46 of the counter electrode active material layer 40. This further reduces the likelihood of short circuits occurring, thereby improving the reliability of the battery 3.

[0116] In this modification, uncovered regions 45 a and 46 a are provided along two of the four sides of the counter electrode active material layer 40 that are perpendicular to each other. No uncovered regions are provided on the remaining two sides, and the end faces of the counter electrode current collector 50 and the counter electrode active material layer 40 are flush with each other. Such a battery 3 can be easily formed by aligning the counter electrode current collector 50 using an L-shaped jig that is aligned along the two sides without uncovered regions when placing the counter electrode current collector 50.

[0117] An uncovered region may be provided on all four sides of the counter electrode active material layer 40. That is, the counter electrode current collector 50 may be smaller than the counter electrode active material layer 40 in a plan view, and the end face of any of the four sides may not be flush with the end face of the counter electrode active material layer 40, forming a step between the counter electrode current collector 50 and the counter electrode active material layer 40.

[0118] The non-covered regions may be provided on only three or only one of the four side portions of the counter electrode active material layer 40. When the non-covered regions are provided on only two side portions, the two side portions on which the non-covered regions are provided may be side portions facing each other.

[0119] [2-3. Modification 3] Next, a battery according to Modification 3 of Embodiment 1 will be described. Fig. 6 is a side view of battery 4 according to this modification.

[0120] As shown in FIG. 6 , the battery 4 according to this modification includes a unit cell 200. The unit cell 200 differs from the unit cell 100 according to the first embodiment in that the unit cell 200 includes two of each of the electrode active material layer 20, solid electrolyte layer 30, counter electrode active material layer 40, and counter electrode current collector 50. In FIG. 6 , one of the two electrode active material layers 20 is shown as electrode active material layer 20A, and the other of the two electrode active material layers 20 is shown as electrode active material layer 20B. Similarly, one of the two solid electrolyte layers 30 is shown as solid electrolyte layer 30A, and the other of the two solid electrolyte layers 30 is shown as solid electrolyte layer 30B. One of the two counter electrode active material layers 40 is shown as counter electrode active material layer 40A, and the other of the two counter electrode active material layers 40 is shown as counter electrode active material layer 40B. One of the two counter electrode current collectors 50 is shown as a counter electrode current collector 50A, and the other of the two counter electrode current collectors 50 is shown as a counter electrode current collector 50B.

[0121] The electrode active material layer 20A, solid electrolyte layer 30A, counter electrode active material layer 40A, and counter electrode current collector 50A are the same as the electrode active material layer 20, solid electrolyte layer 30, counter electrode active material layer 40, and counter electrode current collector 50 provided in the above-described battery 1, 2, or 3, respectively. As shown in Fig. 6 , the electrode active material layer 20A, solid electrolyte layer 30A, counter electrode active material layer 40A, and counter electrode current collector 50A are stacked in this order on the main surface 10a of the electrode current collector 10.

[0122] Except for their different positions, the electrode active material layer 20B, solid electrolyte layer 30B, counter electrode active material layer 40B, and counter electrode current collector 50B are the same as the electrode active material layer 20, solid electrolyte layer 30, counter electrode active material layer 40, and counter electrode current collector 50 included in the above-described battery 1, 2, or 3. The electrode active material layer 20B, solid electrolyte layer 30B, counter electrode active material layer 40B, and counter electrode current collector 50B are laminated in this order on the main surface 10b of the electrode current collector 10.

[0123] As shown in FIG. 6 , the counter electrode current collector 50B is provided with rounded chamfers 53r and 54r, and the main surface 40b of the counter electrode active material layer 40B is provided with uncoated regions 43b and 44b. Although not shown in FIG. 6 , the counter electrode current collector 50B is provided with rounded chamfers 51r and 52r. The main surface 40b of the counter electrode active material layer 40B is provided with uncoated regions corresponding to the uncoated regions 41a and 42a. At least one of the sides of the counter electrode active material layer 40B may be provided with an uncoated region corresponding to the uncoated regions 45a and 46a. At least one of the corners of the counter electrode active material layer 40B may be provided with an rounded chamfer.

[0124] In this way, in the unit cell 200, a structure similar to the laminated structure of the electrode active material layer 20, the solid electrolyte layer 30, the counter electrode active material layer 40, and the counter electrode current collector 50 formed on the main surface 10a of the electrode current collector 10 of the unit cell 100 is also formed on the main surface 10b facing away from the main surface 10a of the electrode current collector 10.

[0125] This allows currents of the two electrode active material layers 20A and 20B to be extracted from one electrode current collector 10, thereby increasing the volumetric energy density. Furthermore, because a laminated structure of the electrode active material layer 20, the solid electrolyte layer 30, the counter electrode active material layer 40, and the counter electrode current collector 50 is formed on both main surfaces 10a and 10b of the electrode current collector 10, when the unit cell 200 is densified by pressing or the like, stresses generated on both sides of the electrode current collector 10 in the stacking direction are unlikely to differ, thereby suppressing warping of the unit cell 200. Furthermore, even if stresses are generated due to expansion and contraction of the electrode active material layer 20 and the counter electrode active material layer 40 during use of the battery 4, stresses generated on both sides of the electrode current collector 10 in the stacking direction are unlikely to differ, thereby suppressing warping of the unit cell 200.

[0126] 3. Manufacturing Method Next, a method for manufacturing the battery according to this embodiment and each of its modifications will be described.

[0127] 7A is a flowchart showing a method for manufacturing a battery according to the present embodiment and each of its modifications. As shown in FIG. 7A , the method for manufacturing a battery according to the present embodiment and each of its modifications includes a step (step S10) of preparing a laminate including, in this order, an electrode current collector 10, an electrode active material layer 20, a solid electrolyte layer 30, and a counter electrode active material layer 40, and a step (step S30) of disposing a counter electrode current collector 50 on the counter electrode active material layer 40. The laminate is also called a laminated electrode plate. In the disposing step (step S30), the counter electrode current collector 50 having at least one of R-chamfered portions 51r, 52r, 53r, and 54r is disposed so as not to cover at least a portion of at least one of corners 41, 42, 43, and 44 of the counter electrode active material layer 40.

[0128] Next, more specific examples of each step shown in Fig. 7A will be described using Fig. 7B. The following mainly describes the method for manufacturing battery 4 according to Variation 3 of Embodiment 1, but other batteries can also be manufactured by appropriately applying the manufacturing method described below. Fig. 7B is a flowchart showing the method for manufacturing battery 4 according to Variation 3 of Embodiment 1.

[0129] The manufacturing method of the battery 4 described below is an example, and the manufacturing method of the battery 4 is not limited to the following example. Furthermore, when there is no need to distinguish between the electrode active material layers 20A and 20B, such as when there is content common to the electrode active material layers 20A and 20B, they will be described as the electrode active material layer 20. Similarly, the solid electrolyte layers 30A and 30B, the counter electrode active material layers 40A and 40B, and the counter electrode current collectors 50A and 50B may also be described as the solid electrolyte layer 30, the counter electrode active material layer 40, and the counter electrode current collector 50, respectively.

[0130] First, in the method for manufacturing the battery 4, the electrode current collector 10 is prepared (step S11). Next, the electrode active material layer 20, the solid electrolyte layer 30, and the counter electrode active material layer 40 are laminated in this order on each of the two main surfaces 10a and 10b of the electrode current collector 10. Specifically, first, the electrode active material layers 20A and 20B are laminated on the main surfaces 10a and 10b of the electrode current collector 10, respectively (step S12). Note that when manufacturing a battery such as the battery 1 in which the electrode active material layer 20B or the like is not laminated on the main surface 10b side, the electrode active material layer 20 is laminated only on the main surface 10a.

[0131] Next, solid electrolyte layers 30A and 30B are laminated on the electrode active material layers 20A and 20B, respectively, on the side opposite to the electrode current collector 10 (step S13).

[0132] Next, counter electrode active material layers 40A and 40B are laminated on the solid electrolyte layers 30A and 30B on the side opposite to the electrode active material layers 20A and 20B (step S14).

[0133] The above steps S11 to S14 correspond to the step (step S10 shown in FIG. 7A ) of preparing a laminate including, in this order, the electrode current collector 10, the electrode active material layer 20, the solid electrolyte layer 30, and the counter electrode active material layer 40. This results in a laminated electrode plate having a structure in which the electrode active material layer 20A, the solid electrolyte layer 30A, and the counter electrode active material layer 40A are laminated in this order from the main surface 10a side on the electrode current collector 10, and the electrode active material layer 20B, the solid electrolyte layer 30B, and the counter electrode active material layer 40B are laminated in this order from the main surface 10b side on the main surface 10b.

[0134] The electrode active material layer 20, the solid electrolyte layer 30, and the counter electrode active material layer 40 are each formed in this order by, for example, a wet coating method. By using the wet coating method, the electrode active material layer 20, the solid electrolyte layer 30, and the counter electrode active material layer 40 can be easily laminated on the electrode current collector 10. As the wet coating method, a coating method such as a die coating method, a doctor blade method, a roll coater method, a screen printing method, or an inkjet method can be used, but the wet coating method is not limited to these methods.

[0135] When the wet coating method is used, a coating step is carried out in which materials for forming the electrode active material layer 20, the solid electrolyte layer 30, and the counter electrode active material layer 40 are appropriately mixed with a solvent to obtain a slurry.

[0136] The solvent used in the coating process may be, for example, a known solvent used in producing a known all-solid-state battery such as a lithium ion all-solid-state battery.

[0137] The slurries for each layer obtained in the coating process are applied to both main surfaces 10a and 10b of the electrode current collector 10 in the order of the electrode active material layer 20, the solid electrolyte layer 30, and the counter electrode active material layer 40. In this case, the next layer may be applied after the previous layer has been applied, or the next layer may be applied while the previous layer is being applied. In other words, steps S12, S13, and S14 shown in FIG. 7B may be performed simultaneously in parallel.

[0138] 7B, a high-pressure press process is performed (step S20). Specifically, the slurry for each layer is applied sequentially, and after all layers are applied, a high-pressure press process is performed to promote filling of the material for each layer.

[0139] It should be noted that high-pressure pressing may be performed after each coating of each layer. The high-pressure pressing may be performed after each coating of the electrode active material layer 20, the solid electrolyte layer 30, and the counter electrode active material layer 40, or may be performed separately after coating of any two layers and after coating of one layer, or may be performed all at once after coating of all three layers. When high-pressure pressing is performed two or more times, the pressing may be performed so that the pressure of the final high-pressure pressing is the highest. For example, a roll press, a plate press, or an isostatic press (ISP) may be used for the high-pressure pressing.

[0140] When the wet coating method is used, a heat treatment is performed to remove the solvent before the high-pressure pressing. The heat treatment is performed, for example, after each application of the electrode active material layer 20, the solid electrolyte layer 30, and the counter electrode active material layer 40, but may also be performed all at once after the electrode active material layer 20, the solid electrolyte layer 30, and the counter electrode active material layer 40 are laminated. At least one of the heat treatment and the high-pressure pressing may not be performed.

[0141] By performing the layered coating method in this manner, it is possible to improve the bonding strength and reduce the interfacial resistance at the interfaces of the electrode current collector 10, the electrode active material layer 20, the solid electrolyte layer 30, and the counter electrode active material layer 40. It is also possible to improve the bonding strength and reduce the grain boundary resistance in the powder materials used in the electrode active material layer 20, the solid electrolyte layer 30, and the counter electrode active material layer 40. That is, good interfaces are formed between the layers of the electrode active material layer 20, the solid electrolyte layer 30, and the counter electrode active material layer 40 and between the powder materials within each layer.

[0142] The above steps S12 to S14 and S20 may be performed in a continuous process such as a roll-to-roll process.

[0143] Furthermore, the laminated electrode plate may have a size in plan view corresponding to one battery 4, or may have a size in plan view that allows it to be divided into individual batteries 4 and used for multiple batteries 4. Manufacturing a laminated electrode plate of a size that allows it to be divided into multiple batteries 4 can improve manufacturing efficiency. The laminated electrode plate may be cut to adjust the size after being divided into individual batteries. Cutting may be performed using a blade such as a cutter, ultrasonic cutter, slitter, dicer, cutting machine, or punching machine with a Thomson blade, or by using a laser or jet, but is not limited to these methods. Furthermore, to prevent short circuits, the side surfaces may be polished after cutting to remove burrs and the like.

[0144] Next, at least one of R-chamfered portions 51r, 52r, 53r, and 54r is formed on each of counter electrode current collectors 50A and 50B to a desired dimension (step S25). For example, R-chamfered portions 51r, 52r, 53r, and 54r are formed by, for example, punching using a press. That is, by punching a metal substrate, each side of counter electrode current collector 50 and R-chamfered portions 51r, 52r, 53r, and 54r can be simultaneously formed. Note that R-chamfered portions 51r, 52r, 53r, and 54r may also be formed by polishing, laser processing, or the like as a post-processing step following punching.

[0145] Next, counter electrode current collectors 50A and 50B are disposed on the opposite side of counter electrode active material layers 40A and 40B from solid electrolyte layers 30A and 30B (step S30). Specifically, counter electrode current collector 50A provided with at least one of R-chamfered portions 51r, 52r, 53r, and 54r is disposed so as not to cover at least a portion of at least one of corners 41, 42, 43, and 44 of counter electrode active material layer 40A. Counter electrode current collector 50B provided with at least one of R-chamfered portions 51r, 52r, 53r, and 54r is disposed so as not to cover at least a portion of at least one of corners 41, 42, 43, and 44 of counter electrode active material layer 40B. That is, counter electrode current collectors 50A and 50B, which have been provided with R-chamfered portions in advance, are placed on the main surface 40a of the counter electrode active material layer 40A and the main surface 40b of the counter electrode active material layer 40B, respectively.

[0146] This results in a laminate (i.e., unit cell 200 shown in FIG. 6 ) in which the electrode active material layer 20, solid electrolyte layer 30, counter electrode active material layer 40, and counter electrode current collector 50 are laminated in this order on both main surfaces 10 a and 10 b of the electrode current collector 10. At this time, the counter electrode active material layer 40 and the counter electrode current collector 50 are bonded to each other by, for example, high-pressure pressing. The bonding may also be performed by coating an adhesive or attaching an adhesive film. The bonding method is not limited to these methods. Heat treatment may also be performed during or after bonding.

[0147] The step of forming the R-chamfered portions 51r, 52r, 53r, and 54r (step S25) may be performed before the step of arranging the counter electrode current collectors 50A and 50B (step S30). For example, the step of forming the R-chamfered portions 51r, 52r, 53r, and 54r (step S25) may be performed simultaneously with the step of preparing the electrode current collector 10 (step S11).

[0148] Alternatively, the step of forming the R-chamfered portions 51r, 52r, 53r, and 54r (step S25) may be performed after the step of arranging the counter electrode current collectors 50A and 50B (step S30). That is, the R-chamfered portions 51r, 52r, 53r, and 54r may be formed by removing part of the corners after the counter electrode current collector 50 is arranged on the counter electrode active material layer 40. Furthermore, for example, the step of forming the R-chamfered portions 41r, 42r, 43r, and 44r (step S22) may be performed after the step of arranging the counter electrode current collectors 50A and 50B (step S30).

[0149] Through the steps described above, a battery 4 composed of one unit cell 200 is obtained. The obtained battery 4 may be housed in an exterior body such as a laminate film or a metal can. When the battery 4 is housed in an exterior body, the electrode current collector 10 and the counter electrode current collector 50 may be provided with protrusions, and the protrusions may be extended to the outside of the exterior body, thereby enabling the current of the battery 4 to be extracted. To extract the current, a method of connecting a lead wire or a metal terminal to the electrode current collector 10 and the counter electrode current collector 50 may also be used.

[0150] Note that some of the steps included in the above-described method for manufacturing battery 4 may be omitted or modified. Alternatively, the above-described method for manufacturing battery 4 may include a new step. Below, a modified example of the method for manufacturing a battery will be described with reference to FIG. 7C. FIG. 7C is a flowchart showing another example of the method for manufacturing a battery according to the first embodiment and each of the modified examples thereof.

[0151] As shown in FIG. 7C, the steps from the step of preparing the electrode current collector 10 (step S11) to the step of forming the counter electrode active material layer 40 (step S14) are the same as the steps shown in FIG. 7B.

[0152] Next, a high-pressure press process is performed (step S20). After the high-pressure press process, a low-pressure press process is performed (step S21). If the pressure of the high-pressure press process is a first pressure, the pressure of the low-pressure press process, a second pressure, is lower than the first pressure. The first pressure is, for example, in the range of 5 MPa or more and 500 MPa or less. The second pressure is, for example, in the range of 0.01 MPa or more and 4 MPa or less. If the second pressure is 5 MPa or more, warping or undulation occurs in the laminated electrode plate, making it difficult to obtain the desired flatness.

[0153] In this way, the low-pressure pressing process increases the flatness of the laminated electrode plate, which in turn increases the accuracy of placement of the counter electrode current collector 50 and the accuracy of the dimensions and positions of the uncovered regions 41 a, 42 a, 43 a, and 44 a and the R-chamfered portions 41 r, 42 r, 43 r, and 44 r in the subsequent steps.

[0154] Next, rounded chamfers 41r, 42r, 43r, and 44r are formed in the counter electrode active material layer 40 (step S22). Specifically, the rounded chamfers 41r, 42r, 43r, and 44r are formed by removing a portion of the corner of the laminated electrode plate. For example, cutting with a blade of a punching die is used, but this method is not limited to this. Furthermore, one or more rounded chamfers may be formed in at least one of the solid electrolyte layer 30, the electrode active material layer 20, and the electrode current collector 10 simultaneously with the counter electrode active material layer 40. This allows the manufacture of batteries 2 and 3 according to Modifications 1 and 2 of Embodiment 1. Note that the formation of the rounded chamfers 41r, 42r, 43r, and 44r (step S22) may be omitted, and only shaping, such as making the end surfaces of the laminated electrode plate uniform, may be performed.

[0155] 7C , after the step of disposing the counter electrode current collector 50 (step S30), the periphery of the unit cell 100 or 200 may be covered with an insulating layer (step S40). The electrode current collector 10, electrode active material layer 20, solid electrolyte layer 30, counter electrode active material layer 40, and counter electrode current collector 50 that constitute the unit cell 100 or 200 each have exposed side surfaces. To protect these exposed side surfaces, an insulating layer such as a sealing member may be disposed to cover these side surfaces. That is, when these side surfaces are covered with another member such as a sealing member, these exposed side surfaces may also be covered with the other member. For example, an insulating resin material may be used as the sealing member.

[0156] (Embodiment 2) Next, embodiment 2 will be described. In embodiment 2, a main difference from embodiment 1 is that tabs for extracting current are provided on each of the electrode current collector 10 and the counter electrode current collector 50. Furthermore, in embodiment 2, a main difference from embodiment 1 is that the electrode current collector 10, the electrode active material layer 20, and the solid electrolyte layer 30 each have an uncovered region at the end where the tab is provided. The following description will focus on the differences from embodiment 1, and description of commonalities will be omitted or simplified.

[0157] First, the configuration of a battery according to embodiment 2 will be described with reference to the drawings. Fig. 8 is a top view of battery 5 according to this embodiment. Fig. 9 is a cross-sectional view of battery 5 according to this embodiment. Fig. 9 shows a cross section taken along line IX-IX in Fig. 8.

[0158] In the battery 5 according to the present embodiment, the electrode current collector 10 and the counter electrode current collector 50 each have a tab for extracting current. Specifically, as shown in FIG. 8 , the electrode current collector 10 has a tab 19. The counter electrode current collector 50 has a tab 59.

[0159] Both tabs 19 and 59 are provided at the ends of battery 5 in a plan view so as to protrude outward. Specifically, as shown in FIG. 8 , both tabs 19 and 59 are provided at the ends facing the positive x-axis direction so as to protrude in the positive x-axis direction. Tabs 19 and 59 protrude in directions parallel to each other. Tabs 19 and 59 are provided so as not to overlap each other in a plan view. This prevents tabs 19 and 59 from coming into contact with each other and causing a short circuit.

[0160] 8 and 9 , the battery 5 according to the present embodiment includes a unit cell 300. In the unit cell 300, similar to the unit cell 200, an electrode active material layer 20, a solid electrolyte layer 30, a counter electrode active material layer 40, and a counter electrode current collector 50 are laminated on both main surfaces 10a and 10b of an electrode current collector 10. The unit cell 300 differs from the unit cell 200 in the configuration of the end portion on which tabs 19 and 59 are provided, i.e., the end portion on the positive side of the x-axis. Specifically, at the end portion on the positive side of the x-axis, an uncovered region is provided on a portion of the main surface of each of the electrode current collector 10, the electrode active material layer 20, the solid electrolyte layer 30, and the counter electrode active material layer 40.

[0161] For example, an uncovered region 16a is provided on the main surface 10a of the electrode current collector 10. The uncovered region 16a is a region that is not covered by the electrode active material layer 20A provided on the main surface 10a of the electrode current collector 10. The uncovered region 16a is a strip-shaped region of a predetermined width that extends along the side of the electrode current collector 10 in the positive x-axis direction. The width of the uncovered region 16a (the length in the x-axis direction) is, for example, not less than 1 mm and not more than 20 mm.

[0162] An uncovered region 26a is provided on the upper surface of the electrode active material layer 20A. Of the two main surfaces of the electrode active material layer 20A, the upper surface is the main surface located in the positive z-axis direction. The uncovered region 26a is a region that is not covered by the solid electrolyte layer 30A provided on the upper surface of the electrode active material layer 20A. The uncovered region 26a is a strip-shaped region of a predetermined width that extends along the side of the electrode active material layer 20A in the positive x-axis direction. The width of the uncovered region 26a (length in the x-axis direction) is, for example, 0.1 mm or more and 5 mm or less, but is not limited to this.

[0163] An uncovered region 36a is provided on the upper surface of the solid electrolyte layer 30A. Of the two main surfaces of the solid electrolyte layer 30A, the upper surface of the solid electrolyte layer 30A is the main surface located in the positive z-axis direction. The uncovered region 36a is a region that is not covered by the counter electrode active material layer 40A provided on the upper surface of the solid electrolyte layer 30A. The uncovered region 36a is a strip-shaped region of a predetermined width that extends along the side of the solid electrolyte layer 30A in the positive x-axis direction. The width of the uncovered region 36a (length in the x-axis direction) is, for example, 0.1 mm or more and 5 mm or less, but is not limited to this.

[0164] An uncovered region 46a is provided on the main surface 40a of the counter electrode active material layer 40A. The uncovered region 46a is the same as the uncovered region 46a provided in the battery 3. The width (length in the x-axis direction) of the uncovered region 46a is, for example, 0.1 mm or more and 5 mm or less, but is not limited to this.

[0165] Thus, at the ends where the tabs 19 and 59 are provided, the ends of the electrode current collector 10, the electrode active material layer 20A, the solid electrolyte layer 30A, the counter electrode active material layer 40A, and the counter electrode current collector 50A are each formed in a stepped shape. The same applies to the ends of the electrode active material layer 20B, the solid electrolyte layer 30B, the counter electrode active material layer 40B, and the counter electrode current collector 50B. For example, as shown in FIG. 9 , an uncovered region 16b is provided on the main surface 10b of the electrode current collector 10. An uncovered region 26b is provided on the lower surface of the electrode active material layer 20B. An uncovered region 36b is provided on the lower surface of the solid electrolyte layer 30B. An uncovered region 46b is provided on the main surface 40b of the counter electrode active material layer 40B. The uncovered regions 16b, 26b, 36b, and 46b have the same configuration as the uncovered regions 16a, 26a, 36a, and 46a, respectively.

[0166] The provision of the uncovered regions 16a, 26a, and 36a increases the distance between the electrode active material layer 20A and the electrode current collector 10 and the counter electrode active material layer 40A and the counter electrode current collector 50A, which have opposite polarities. Similarly, the provision of the uncovered regions 16b, 26b, and 36b increases the distance between the electrode active material layer 20B and the electrode current collector 10 and the counter electrode active material layer 40B and the counter electrode current collector 50B, which have opposite polarities. This reduces the likelihood of contact between electrode layers, current collectors, or electrode layers and current collectors, which can prevent short circuits. This improves the reliability of the battery 5. Furthermore, for example, the tolerance for misalignment due to coating and pressing during the formation of the electrode active material layers 20A and 20B, solid electrolyte layers 30A and 30B, and counter electrode active material layers 40A and 40B is large, facilitating the manufacture of the battery 5 and achieving improved productivity and reduced costs.

[0167] The battery 5 according to this embodiment also includes insulating layers 60A and 60B. The insulating layers 60A and 60B are each an example of an insulating layer that covers the periphery of the unit cell 300. The insulating layers 60A and 60B are formed using an insulating resin that has electronic and ionic insulating properties. For example, a thermosetting resin, a photo-curable resin such as an ultraviolet ray curable resin, or an electron beam curable resin can be used for the insulating layers 60A and 60B. Specifically, a silicone resin, an epoxy resin, an acrylic resin, a polyimide resin, or the like can be used for the insulating layers 60A and 60B.

[0168] The insulating layers 60A and 60B are formed, for example, by applying a liquid resin composition and then curing it by heating or by irradiating it with light or an electron beam. Alternatively, the insulating layers 60A and 60B may be formed by attaching an insulating resin in the form of an adhesive tape. The insulating layers 60A and 60B are formed before the counter electrode current collector 50 is disposed, but may also be formed after the counter electrode current collector 50 is disposed, as in step S40 shown in FIG. 7C .

[0169] Note that the battery 5 according to this embodiment may have multiple pairs of tabs 19 and 59. For example, a pair of tabs 19 and 59 may be provided at both the positive x-axis end and the negative x-axis end of the battery 5. Alternatively, a pair of tabs 19 and 59 may be provided at either the positive x-axis end or the negative x-axis end of the battery 5 and at either the positive y-axis end or the negative y-axis end of the battery 5. Alternatively, four pairs of tabs 19 and 59 may be provided on any of the four sides of the battery 5. Furthermore, the tabs 19 and 59 may be provided separately at two different ends of the battery 5. For example, the tab 19 may be provided at the end in the positive x-axis direction, and the tab 59 may be provided at the end in the negative x-axis, the positive y-axis, or the negative y-axis.

[0170] Furthermore, the ends of the electrode active material layer 20A, the solid electrolyte layer 30A, and the counter electrode active material layer 40A do not have to be stepped. For example, the ends of the electrode active material layer 20A, the solid electrolyte layer 30A, and the counter electrode active material layer 40A may be pressed to form an obliquely inclined surface. That is, at the end of each layer, the main surface and the end surface may not be clearly distinguishable. The inclined surface may be flat, curved, or include fine irregularities. For example, the end of each layer may have irregular projections or depressions. Furthermore, at the end of each layer, one layer may be recessed into the other layer. For example, the end of the solid electrolyte layer 30A may be recessed into the end of the electrode active material layer 20A. In other words, at the end of the solid electrolyte layer 30A, a projection protruding toward the electrode active material layer 20A may be provided on the lower surface, and at the end of the electrode active material layer 20A, a recess into which the projection is inserted may be provided on the upper surface. Similarly, the ends of the electrode active material layer 20B, the solid electrolyte layer 30B, and the counter electrode active material layer 40B do not have to be stepped.

[0171] Furthermore, the uncovered regions 26a and 36a may not be provided at the ends where the tabs 19 and 59 are provided. For example, at the ends where the tabs 19 and 59 are provided, the solid electrolyte layer 30A may completely cover the ends of the electrode active material layer 20A and may be in contact with a portion of the main surface 10a of the electrode current collector 10. Similarly, the uncovered regions 26b and 36b may not be provided. Furthermore, for example, at the ends where the tabs 19 and 59 are provided, the end faces of the electrode active material layer 20A, the solid electrolyte layer 30A, and the counter electrode active material layer 40A may be flush with a flat surface parallel to the z-axis. Similarly, the end faces of the electrode active material layer 20B, the solid electrolyte layer 30B, and the counter electrode active material layer 40B may be flush with a flat surface parallel to the z-axis.

[0172] Furthermore, the battery 5 according to this embodiment does not necessarily have to include the electrode active material layer 20B, the solid electrolyte layer 30B, the counter electrode active material layer 40B, and the counter electrode current collector 50B.

[0173] Third Embodiment Next, a third embodiment will be described. In the third embodiment, a stacked battery in which a plurality of unit cells are stacked will be described. In the following description, differences from the first embodiment and the modifications will be mainly described, and descriptions of commonalities will be omitted or simplified as appropriate.

[0174] [1. Configuration] First, the configuration of a battery according to embodiment 3 will be described with reference to the drawings. Fig. 10 is a side view of a battery 6 according to this embodiment. As shown in Fig. 10, the battery 6 includes a plurality of unit cells 200 according to variation 3 of embodiment 1. The plurality of unit cells 200 are stacked.

[0175] As described above, each of the plurality of unit cells 200 included in the battery 6 has R-chamfered portions 51r, 52r, 53r, and 54r provided at the corners of the counter electrode current collector 50. Each of the plurality of unit cells 200 is less likely to short-circuit and is highly reliable. In the stacked battery 6, the highly reliable unit cells 200 are stacked, thereby improving the reliability of the battery 6.

[0176] In the example shown in Fig. 10, the number of stacked unit cells 200 is four, but it may be two, three, or five or more. In Fig. 10, the four unit cells 200 are represented as unit cells 200A, 200B, 200C, and 200D, respectively. In the following, when it is not necessary to distinguish between the four unit cells 200A, 200B, 200C, and 200D, they will be described as unit cells 200.

[0177] In this embodiment, the multiple unit cells 200 have the same configuration and are stacked so as to be electrically connected in parallel. The electrode active material layer 20, the solid electrolyte layer 30, and the counter electrode active material layer 40, which are stacked on both main surfaces of the electrode current collector 10, are stacked in the same order from the electrode current collector 10. The multiple unit cells 200 are stacked such that the positions of the side surfaces of the unit cells 200 coincide when viewed from the stacking direction. Therefore, the side surfaces of the multiple unit cells 200 in the positive x-axis direction, the negative x-axis direction, the positive y-axis direction, and the negative y-axis direction are flush with each other. Note that, like the unit cell 300 included in the battery 5 according to embodiment 2, each of the multiple unit cells 200 may have tabs 19 and 59.

[0178] 10 , two adjacent unit cells 200 share a counter electrode current collector 50. For example, the counter electrode current collector 50B of the unit cell 200A is also the counter electrode current collector 50A of the unit cell 200B. Alternatively, the two adjacent unit cells 200 may not share the counter electrode current collector 50, but each may have its own counter electrode current collector 50, with two counter electrode current collectors 50 overlapping between the counter electrode active material layers 40. In this case, a conductive adhesive layer may be provided between the two counter electrode current collectors 50.

[0179] In the stacked-type battery 6 according to the present embodiment, the unit cells to be stacked may be unit cells other than the unit cell 200 according to the first embodiment and each of the modified examples described above. Even when unit cells other than the unit cell 200 are stacked, two adjacent unit cells may share a current collector, or the unit cells may be stacked such that two separate current collectors are stacked without sharing a current collector. Furthermore, when unit cells are stacked, such as the unit cell 100, in which the electrode active material layer 20, the solid electrolyte layer 30, the counter electrode active material layer 40, and the counter electrode current collector 50 are stacked only on one main surface 10a of the electrode current collector 10, the unit cells may be stacked so as to be electrically connected in series.

[0180] [2. Manufacturing Method] Next, a method for manufacturing the battery 6 according to this embodiment will be described. The following mainly describes a method for manufacturing the battery 6 formed by stacking a plurality of unit cells 200. However, batteries formed by stacking unit cells other than the unit cells 200 according to the first embodiment and each of the modifications described above can also be manufactured by appropriately applying the manufacturing method described below. Figure 11 is a flowchart showing a method for manufacturing the battery 6 according to the third embodiment. Note that the manufacturing method for the battery 6 described below is an example, and the manufacturing method for the battery 6 is not limited to the following example.

[0181] First, in steps S11 to S20 shown in Fig. 11, a laminated electrode plate and a counter electrode current collector 50 having R-chamfered portions 51r, 52r, 53r, and 54r are formed by a method similar to steps S11 to S20 shown in Fig. 7B and described above. At this time, a plurality of laminated electrode plates and a plurality of counter electrode current collectors 50 are formed.

[0182] Next, a plurality of counter electrode current collectors 50 are arranged so that the counter electrode current collectors 50 and the laminated electrode plates are arranged alternately, thereby forming a stacked structure of a plurality of unit cells 200 as shown in Fig. 10 (step S50). The counter electrode current collector 50 is sandwiched between and contacts the counter electrode active material layers 40 included in two adjacent laminated electrode plates. In this way, the counter electrode current collector 50 is shared by the adjacent unit cells 200, and the counter electrode current collector 50 is placed on the counter electrode active material layers 40 and a plurality of laminated electrode plates are stacked.

[0183] Alternatively, the counter electrode current collector 50 may be disposed on only one of the two counter electrode active material layers 40A and 40B of the laminated electrode plate, and no counter electrode current collector 50 may be disposed on the other of the two counter electrode active material layers 40A and 40B. That is, a unit cell having a structure in which one counter electrode current collector 50 is removed from the unit cell 200 may be formed, and this unit cell may be stacked. This unit cell may also be stacked such that the counter electrode current collector 50 is sandwiched between the counter electrode active material layers 40, so that the counter electrode current collector 50 is shared by adjacent unit cells 200. In this case, after stacking the required number of unit cells 200, a counter electrode current collector 50 is stacked on the counter electrode active material layer 40 at the end in the stacking direction and therefore not stacked with a counter electrode current collector 50.

[0184] 11 , after a stacked structure of the plurality of unit cells 200 is formed, a batch pressing process is performed (step S60). Specifically, the plurality of unit cells 200 are pressed together. The batch pressing process is, for example, a high-pressure pressing process. The counter electrode active material layer 40 and the counter electrode current collector 50 can be bonded together by the batch pressing process. Note that the final batch pressing is not essential, and the high-pressure pressing process may be performed each time one or two stacked electrode plates and one or two counter electrode current collectors 50 are stacked together.

[0185] In the present embodiment, the counter electrode current collector 50 has the R-chamfered portions 51r, 52r, 53r, and 54r formed to a desired dimension before stacking, but this is not limiting. The R-shape may be formed by removing a part of the corner after stacking the counter electrode current collector 50.

[0186] In addition, when two adjacent unit cells 200 do not share a counter electrode current collector 50 but have two counter electrode current collectors 50 stacked between the counter electrode active material layers 40, a laminated electrode plate obtained by performing steps up to step S30 shown in FIG. 7B , i.e., unit cells 200 including the counter electrode current collectors 50, may be stacked. In this case, the unit cells 200 are bonded to each other using a conductive adhesive layer formed by coating an adhesive or laminating an adhesive film. However, the bonding method is not limited to these methods. Furthermore, heat treatment and pressing may be performed after bonding.

[0187] The side surfaces of the electrode current collector 10, electrode active material layer 20, solid electrolyte layer 30, counter electrode active material layer 40, and counter electrode current collector 50 constituting the plurality of unit cells 200 fabricated through the above steps are exposed, and in order to protect these side surfaces, an insulating layer such as a sealing member may be disposed to cover these exposed side surfaces. In other words, when these side surfaces are covered with another member such as a sealing member, these exposed side surfaces may also be covered with the other member. As the sealing member, for example, an insulating resin material can be used.

[0188] Through the steps described above, a battery 6 having a structure in which a plurality of unit cells 200 are stacked is obtained. The obtained battery 6 may be housed in an exterior body such as a laminate film or a metal can. When the battery 6 is housed in an exterior body, the electrode current collector 10 and the counter electrode current collector 50 may be provided with protrusions, and the protrusions may be extended to the outside of the exterior body, thereby enabling current to be extracted from the battery 6. To extract the current, a method of connecting lead wires or metal terminals to the electrode current collector 10 and the counter electrode current collector 50 may also be used.

[0189] While the battery and its manufacturing method according to the present disclosure have 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 a person 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.

[0190] For example, in the above-described embodiments, the battery is composed of an electrode current collector, an electrode active material layer, a solid electrolyte layer, a counter electrode active material layer, and a counter electrode current collector, or is composed of an electrode current collector, an electrode active material layer, a solid electrolyte layer, a counter electrode active material layer, a counter electrode current collector, and an insulating layer, but is not limited thereto. For example, within the range of allowable battery characteristics, a bonding layer or the like may be provided between each layer of the battery for reducing electrical resistance and improving bonding strength.

[0191] In the above embodiment, the electrode active material layer, the solid electrolyte layer, and the counter electrode active material layer are formed by sequentially stacking them directly on the main surface of the electrode current collector, but this is not limited thereto. For example, the electrode active material layer, the solid electrolyte layer, and the counter electrode active material layer may be formed by sequentially stacking them on a sheet-like substrate, and the formed electrode active material layer, the solid electrolyte layer, and the counter electrode active material layer may be removed from the substrate and stacked on the main surface of the electrode current collector. Alternatively, the electrode active material layer, the solid electrolyte layer, and the counter electrode active material layer may be formed on a sheet-like substrate, and the formed electrode active material layer, the solid electrolyte layer, and the counter electrode active material layer may be stacked by sequentially transferring them to the main surface of the electrode current collector.

[0192] In addition, for example, in the above-described embodiment, a part of the counter electrode current collector may protrude outward beyond the counter electrode active material layer in a plan view. For example, the counter electrode current collector may be larger than the counter electrode active material layer in a plan view.

[0193] Furthermore, various modifications, substitutions, additions, omissions, etc. can be made to each of the above-described embodiments within the scope of the claims or their equivalents.

[0194] The battery according to the present disclosure can be used as a secondary battery such as an all-solid-state battery used in various electronic devices, electrical appliances, automobiles, etc.

[0195] 1, 2, 3, 4, 5, 6 Battery 10 Electrode current collector 10a, 10b, 40a, 40b Main surface 16a, 16b, 26a, 26b, 36a, 36b, 41a, 42a, 43a, 43b, 44a, 44b, 45a, 46a, 46b Uncovered region 19, 59 Tab 20, 20A, 20B Electrode active material layer 30, 30A, 30B Solid electrolyte layer 40, 40A, 40B Counter electrode active material layer 41, 42, 43, 44, 51, 52, 53, 54 Corner portion 41r, 42r, 43r, 44r, 51r, 52r, 53r, 54r R-chamfered portion 45, 46 Side portion 50, 50A, 50B Counter electrode current collector 60A, 60B Insulating layer 100, 200, 200A, 200B, 200C, 200D, 300 Unit cell

Claims

1. A battery comprising a unit cell including, in this order, an electrode current collector, an electrode active material layer, a solid electrolyte layer, a counter electrode active material layer, and a counter electrode current collector, wherein, in a plan view of the counter electrode current collector, at least one of a plurality of corners of the counter electrode active material layer has an uncovered region that is not covered by the counter electrode current collector, and a first rounded portion having an R-chamfered shape is provided at the corner of the plurality of corners of the counter electrode current collector where the uncovered region is provided.

2. The battery according to claim 1, wherein the corner where the non-covered region is provided among the plurality of corners of the counter electrode active material layer is provided with a second rounded portion having an R-chamfered shape.

3. The battery according to claim 2, wherein, when the radius of the R-chamfered shape of the first rounded portion is R1 and the radius of the R-chamfered shape of the second rounded portion is R2, the following relationship is satisfied: R2<R1.

4. The battery according to any one of claims 1 to 3, wherein the non-covered region is further provided on at least one of a plurality of side portions of the counter electrode active material layer.

5. The battery according to any one of claims 1 to 3, wherein the electrode active material layer contains a negative electrode active material, and the counter electrode active material layer contains a positive electrode active material.

6. The battery according to any one of claims 1 to 3, wherein the unit cell includes two of each of the electrode active material layer, the solid electrolyte layer, the counter electrode active material layer, and the counter electrode current collector, the electrode current collector having a first main surface and a second main surface opposite to the first main surface, one of the two electrode active material layers, one of the two solid electrolyte layers, one of the two counter electrode active material layers, and one of the two counter electrode current collectors are stacked in this order on the first main surface, and the other of the two electrode active material layers, the other of the two solid electrolyte layers, the other of the two counter electrode active material layers, and the other of the two counter electrode current collectors are stacked in this order on the second main surface.

7. The battery according to any one of claims 1 to 3, further comprising an insulating layer covering the periphery of the unit cell.

8. The battery according to any one of claims 1 to 3, comprising a plurality of the unit cells, the plurality of unit cells being stacked.

9. A method for manufacturing a battery, comprising: preparing a laminate including, in this order, an electrode current collector, an electrode active material layer, a solid electrolyte layer, and a counter electrode active material layer; and arranging a counter electrode current collector on the counter electrode active material layer, wherein, in a plan view of the counter electrode current collector, at least one of a plurality of corners of the counter electrode active material layer is provided with an uncovered region that is not covered by the counter electrode current collector, and one of the plurality of corners of the counter electrode current collector that is provided with the uncovered region is provided with a first rounded portion having an R-chamfered shape.

10. The method for manufacturing a battery according to claim 9, further comprising the step of forming the first rounded portion on the counter electrode current collector, wherein in the arranging step, the counter electrode current collector provided with the first rounded portion is arranged so as not to cover at least a portion of at least one of a plurality of corners of the counter electrode active material layer, thereby forming the uncovered region in the counter electrode active material layer.

11. The method for manufacturing a battery according to claim 10, further comprising the step of forming a second rounded portion having an R-chamfered shape on at least one of the plurality of corners of the counter electrode active material layer.

12. The method for manufacturing a battery according to claim 11, wherein in the placing step, the counter electrode current collector provided with the first rounded portion is placed so as not to cover at least a part of the corner provided with the second rounded portion, thereby forming the uncovered region in the counter electrode active material layer.

13. The method for manufacturing a battery according to claim 11, wherein, when the radius of the R-chamfered shape of the first rounded portion is R1 and the radius of the R-chamfered shape of the second rounded portion is R2, the relationship R2<R1 is satisfied.

14. The method for manufacturing a battery according to any one of claims 9 to 13, wherein in the placing step, the counter electrode current collector is placed so as not to cover at least a portion of at least one of a plurality of side portions of the counter electrode active material layer.

15. The method for manufacturing a battery according to any one of claims 9 to 13, wherein the electrode active material layer contains a negative electrode active material, and the counter electrode active material layer contains a positive electrode active material.

16. A method for manufacturing a battery according to any one of claims 9 to 13, wherein the preparing step comprises: preparing the electrode current collector having a first main surface and a second main surface opposite the first main surface; stacking the electrode active material layer, the solid electrolyte layer, and the counter electrode active material layer in this order on each of the first main surface and the second main surface; and the arranging step comprises preparing two counter electrode current collectors; and arranging the two prepared counter electrode current collectors on the main surfaces of the two counter electrode active material layers opposite the solid electrolyte layer.

17. The method for manufacturing a battery according to any one of claims 9 to 13, further comprising the step of covering the peripheral edge of the laminate with an insulating layer.

18. The method for manufacturing a battery according to any one of claims 9 to 13, further comprising the step of stacking a plurality of said laminates.

19. A method for manufacturing a battery according to any one of claims 9 to 13, further comprising: in the step of preparing the laminate, preparing a plurality of the laminates; in the step of arranging the counter electrode current collectors, preparing a plurality of the counter electrode current collectors and arranging the plurality of counter electrode current collectors so that the counter electrode current collectors and the laminates are alternately arranged in stacking order; and after the step of arranging the plurality of counter electrode current collectors, further comprising a step of collectively pressing the plurality of laminates.

20. The method for manufacturing a battery according to any one of claims 9 to 13, further comprising the step of pressing the stack at a first pressure before the step of disposing the counter electrode current collector, and then pressing the stack at a second pressure lower than the first pressure.

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