Battery and battery manufacturing method

Abstract

A battery according to the present disclosure comprises: a power generation element; and a current collector laminated on the power generation element. In a region where the current collector and the power generation element overlap when viewed along a lamination direction of the power generation element and the current collector, the ratio of a second thickness, which is the maximum thickness at an end portion of the current collector, to a first thickness, which is the thickness of a central portion of the current collector, is 101-200%.

Description

Battery and method for manufacturing the battery

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

[0002] Patent Document 1 discloses a method for manufacturing a thin-film battery in which a cutting blade is advanced from the side of a raw sheet of a battery stack of power generating elements to perform cutting.

[0003] Patent Document 2 discloses that in the battery cutting process, the cutting blade is slid in the length direction to cut off the battery. The battery disclosed in Patent Document 2 has linear cut marks that are inclined relative to the thickness direction of the battery cell.

[0004] Patent Document 3 discloses a method for manufacturing a battery, which includes a first cutting step in which a laminate including battery cells is cut at a first cutting position to form a first cut surface, and a second cutting step in which the laminate is further cut at a second cutting position that is more inward than the first cut surface to form a second cut surface.

[0005] JP 2000-188099 A International Publication No. 2022 / 239486 International Publication No. 2022 / 270042

[0006] In the prior art, further improvements in battery reliability are desired.

[0007] Therefore, the present disclosure provides a highly reliable battery and a method for manufacturing the battery.

[0008] A battery according to one aspect of the present disclosure includes a power generating element and a current collector stacked on the power generating element, and in a region where the current collector and the power generating element overlap when viewed along the stacking direction of the power generating element and the current collector, a ratio of a second thickness that is the maximum thickness at an end of the current collector to a first thickness that is the thickness at the center of the current collector is 101% or more and 200% or less.

[0009] A method for manufacturing a battery according to one embodiment of the present disclosure includes the steps of preparing a laminate in which a power generating element and a current collector are stacked, and cutting an end face of the laminate in a direction at 90° to the stacking direction of the power generating element and the current collector.

[0010] According to the present disclosure, a highly reliable battery and a method for manufacturing the battery can be provided.

[0011] FIG. 1 is a perspective view of a battery according to an embodiment. FIG. 2 is a side view of a battery according to an embodiment. FIG. 3 is a cross-sectional view of a battery according to an embodiment. FIG. 4 is a flowchart showing an example of a method for manufacturing a battery according to an embodiment. FIG. 5 is a perspective view showing a state after a laminate has been cut. FIG. 6 is a cross-sectional view of the laminate remaining after cutting the laminate. FIG. 7 is a perspective view for explaining a cutting process.

[0012] (Findings that Form the Basis of the Present Disclosure) In order to improve the reliability of a battery that includes a power generating element having a positive electrode layer and a negative electrode layer, one of the important qualities is to prevent short circuits between the positive electrode layer and the negative electrode layer in the power generating element.

[0013] Short circuits between the positive electrode layer and the negative electrode layer in the power generating element are particularly likely to occur at the ends of the battery. Short circuits between the positive electrode layer and the negative electrode layer at the ends of the battery are caused, for example, by the adhesion of foreign matter, the collapse of each layer of the power generating element, and burrs formed on the current collector. For example, in the process of cutting a battery to a predetermined size during battery manufacturing, adhesion of cutting powder from the conductive current collector and active material layer, foreign matter adhered during the cutting process, burrs on the current collector, and the collapse of the positive electrode layer and the negative electrode layer may form minute conductive paths on the cut surfaces formed as the end faces of the battery, resulting in electrical conduction between the positive and negative electrodes.

[0014] The present disclosure has been made based on the above findings, and provides a highly reliable battery and a method for manufacturing the battery.

[0015] (Summary of the Present Disclosure) As an overview of the present disclosure, examples of a battery and a method for manufacturing a battery according to the present disclosure will be described below.

[0016] For example, a battery according to a first aspect of the present disclosure includes a power generating element and a current collector stacked on the power generating element, and in a region where the current collector and the power generating element overlap when viewed along the stacking direction of the power generating element and the current collector, the ratio of a second thickness, which is the maximum thickness at an end of the current collector, to a first thickness, which is the thickness at the center of the current collector, is 101% or more and 200% or less.

[0017] This allows the end of the current collector to sink into the power generating element, covering the end face of the power generating element, and suppresses collapse of the power generating element. Therefore, short-circuiting of the positive and negative electrodes of the power generating element due to collapse can be suppressed. Furthermore, because the second thickness is 200% or less of the first thickness, the current collector is less likely to come into contact with both the positive and negative electrodes of one power generating element, suppressing short-circuiting of the positive and negative electrodes by the current collector. This improves the reliability of the battery.

[0018] Furthermore, for example, a battery according to a second aspect of the present disclosure may be the battery according to the first aspect, wherein the second thickness is greater than the first thickness by 0.2 μm or more and 5 μm or less.

[0019] This can enhance the effect of improving reliability due to the ratio of the second thickness to the first thickness.

[0020] Furthermore, for example, a battery according to a third aspect of the present disclosure is a battery according to the first or second aspect, and when the current collector is viewed from the end side, the length of the end face of the current collector in the stacking direction may not be constant.

[0021] This makes it difficult for the current collector and the power generating element to slide in a direction perpendicular to the stacking direction, thereby preventing the current collector and the power generating element from peeling off from each other.

[0022] Furthermore, for example, a battery according to a fourth aspect of the present disclosure may be a battery according to any one of the first to third aspects, wherein the ends of the current collector extend further on both sides in the stacking direction than the central portion of the current collector.

[0023] As a result, even if the second thickness is thicker than the first thickness, the ends of the current collector are thickened and spread out on both sides in the stacking direction, making it less likely that a short circuit will occur between the positive and negative electrodes of the power generating element via the current collector.

[0024] Furthermore, for example, a battery according to a fifth aspect of the present disclosure is a battery according to any one of the first to fourth aspects, wherein when the current collector is viewed from the end side, a linear recess or protrusion is provided on the end face of the current collector, and the angle that the linear recess or protrusion forms with the stacking direction may be 90°.

[0025] This allows the terminal to be caught in the concave or convex portion on the line when connecting the terminal to the end face of the current collector, making it less likely for the terminal to shift in the stacking direction and preventing short-circuiting between the positive and negative electrodes of the power generating element via the terminal.

[0026] Furthermore, for example, a battery according to a sixth aspect of the present disclosure may be the battery according to any one of the first to fifth aspects, wherein the power-generating element has a positive electrode layer, a negative electrode layer, and a solid electrolyte layer located between the positive electrode layer and the negative electrode layer.

[0027] In a solid-state battery having such a solid electrolyte layer, not only the positive electrode layer and the negative electrode layer but also the solid electrolyte layer may collapse. However, by covering the power generating element with the end of the current collector, the collapse of the solid electrolyte layer can also be suppressed.

[0028] Furthermore, for example, a method for manufacturing a battery according to the seventh aspect of the present disclosure includes the steps of preparing a laminate in which a power generating element and a current collector are stacked, and cutting an end face of the laminate in a direction at an angle of 90° to the stacking direction of the power generating element and the current collector.

[0029] As a result, when the end face of the laminate is cut, fine plastic flow occurs in the current collector structure, causing the structure of the current collector near the end face to escape in the stacking direction. This causes the end of the current collector to protrude in the stacking direction, increasing the thickness of the end of the current collector. Furthermore, the plastically flowed current collector structure sinks into the end face of the power-generating element. Therefore, a highly reliable battery having the above structure can be manufactured. Furthermore, because the end face of the laminate is cut in a direction 90° to the stacking direction, it is possible to weaken the force applied in the stacking direction, which is a direction that would peel off the layers and current collector of the power-generating element at the end face of the laminate, during cutting. Therefore, damage during battery manufacturing is suppressed.

[0030] Also, for example, a battery manufacturing method according to an eighth aspect of the present disclosure is a battery manufacturing method according to the seventh aspect, in which, in the cutting step, the end face of the laminate is cut with a cutting blade while the end face is pressed against the cutting blade.

[0031] This allows the current collector to be cut to a greater extent by being plastically flowed and embedded in its structure.

[0032] Also, for example, a method for manufacturing a battery according to a ninth aspect of the present disclosure is a method for manufacturing a battery according to the seventh or eighth aspect, further including, before the cutting step, a step of cutting the laminate to form a cut surface as the end surface.

[0033] This makes it possible to cut off the edges of the laminate that are difficult to function as a battery, thereby increasing the capacity density of the manufactured battery. Furthermore, cutting the laminate to a desired size can also improve the capacity precision of the battery. On the other hand, cutting the laminate increases the possibility of short-circuiting between the positive and negative electrodes of the power-generating element due to the generation of burrs on the current collectors and the collapse of the power-generating element at the cut surface. Therefore, by grinding the cut surface formed by cutting the laminate as described above, it is possible to remove burrs on the current collectors and the collapsed parts of the power-generating element, thereby manufacturing a highly reliable battery.

[0034] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.

[0035] The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection configurations, processes (steps), and process (step) orders shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Furthermore, among the components in the following embodiments, components not described in independent claims are described as optional components.

[0036] 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.

[0037] Furthermore, in this specification, terms indicating the relationship between elements, such as parallel and perpendicular, terms indicating the shape of elements, such as rectangle, 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.

[0038] In this specification and drawings, the x-axis, y-axis, and z-axis refer to the three axes of a three-dimensional Cartesian coordinate system. When the shape of the battery in plan view is rectangular, the x-axis and y-axis correspond to directions parallel to a first side of the rectangle and a second side perpendicular to the first side. The z-axis corresponds to the stacking direction of the layers of the power-generating element and the current collector.

[0039] In this specification, the "stacking direction" corresponds to the direction normal to the main surface of each layer of the current collector and the power-generating element. In this specification, the term "plan view" refers to a view perpendicular to the main surface of the battery or power-generating element, unless otherwise specified. When the term "plan view of a certain surface," such as "plan view of a cross section," is used, it refers to a view of the "certain surface" from the front.

[0040] 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, unless otherwise specified, the negative side of the z axis will be referred to as "lower" or "lower side," and the positive side of the z axis will be referred to as "upper" or "upper side."

[0041] (Embodiment) [Configuration] First, the configuration of the battery according to this embodiment will be described.

[0042] FIG. 1 is a perspective view of a battery 100 according to the present embodiment. FIG. 2 is a side view of the battery 100 according to the present embodiment. That is, FIG. 2 is a plan view of a side surface 160 of the battery 100 as viewed from the front. In the illustrated example, the side surface 160 is the end surface of the battery 100 on the negative side in the y-axis direction. FIG. 3 is a cross-sectional view of the battery 100 according to the present embodiment. Specifically, FIG. 3 is a cross-sectional view of the battery 100 when the battery 100 is cut parallel to the stacking direction (z-axis direction) and perpendicular to the side surface 160. Note that FIG. 1 does not depict the linear pattern 150a shown in FIG. 2. Furthermore, in the perspective views such as FIG. 1, for ease of viewing, the side surfaces of each layer are marked with the same diagonal lines as in the cross-sectional views, but this does not mean that diagonal patterns are provided on the side surfaces of each layer.

[0043] The battery 100 includes a plurality of power generating elements 200 and a plurality of current collectors 150. In the battery 100, the current collectors 150 are stacked on the power generating elements 200. The battery 100 is, for example, an all-solid-state battery.

[0044] As shown in FIG. 1 , the shape of battery 100 in a plan view is, for example, rectangular. Battery 100 may have, for example, a flattened rectangular parallelepiped shape. Here, "flat" means that the thickness (i.e., the length in the z-axis direction) is shorter than each side of the main surface (i.e., the lengths in the x-axis direction and the y-axis direction) or the maximum width. The shape of battery 100 in a plan view may be a square, a parallelogram, a rhombus, or another quadrilateral, or a hexagon, or another polygon, such as an octagon. Furthermore, battery 100 may have, for example, a rectangular parallelepiped shape, but may also have other shapes, such as a cube, a square truncated pyramid, or a polygonal column. In the drawings illustrating this embodiment, the thickness of each layer is exaggerated to make the layer structure of battery 100 easier to understand.

[0045] In the illustrated example, the power generating element 200 is a battery with a minimum configuration and is also referred to as a unit cell. The multiple power generating elements 200 are stacked so as to be electrically connected in parallel. In the illustrated example, the battery 100 includes two power generating elements 200, but this is not limited to this. For example, the number of power generating elements 200 included in the battery 100 may be one, or three or more. Furthermore, when the battery 100 includes three or more power generating elements 200, all of the power generating elements 200 included in the battery 100 may be electrically connected in parallel, or the multiple power generating elements 200 may be connected in a combination of parallel and series connections.

[0046] Each of the plurality of power generating elements 200 has an electrode layer 110, a counter electrode layer 120, and a solid electrolyte layer 130 located between the electrode layer 110 and the counter electrode layer 120. Therefore, each of the plurality of power generating elements 200 has a structure in which the electrode layer 110, the solid electrolyte layer 130, and the counter electrode layer 120 are stacked in this order. The electrode layer 110 and the counter electrode layer 120 each contain an active material, and are also referred to as an electrode active material layer and a counter electrode active material layer.

[0047] The electrode layer 110 is one of the positive electrode layer and the negative electrode layer of the power generating element 200. The counter electrode layer 120 is the other of the positive electrode layer and the negative electrode layer of the power generating element 200. In the following, a case where the electrode layer 110 is the negative electrode layer and the counter electrode layer 120 is the positive electrode layer will be described as an example. Note that the electrode layer 110 may be the positive electrode layer and the counter electrode layer 120 may be the negative electrode layer.

[0048] The multiple power generating elements 200 have substantially the same configuration. In two adjacent power generating elements 200, the order of the layers constituting the power generating elements 200 is reversed in the vertical direction. In other words, the multiple power generating elements 200 are stacked side by side along the z-axis while the order of the layers constituting the power generating elements 200 is alternately reversed. In other words, adjacent power generating elements 200 are stacked so that the same poles are electrically connected via the current collectors 150.

[0049] Each of the multiple current collectors 150 functions as an electrode current collector electrically connected to the electrode layer 110 or a counter electrode current collector electrically connected to the counter electrode layer 120. The electrode layer 110 is laminated on at least one main surface of the current collector 150 functioning as an electrode current collector, without the solid electrolyte layer 130 interposed therebetween. The counter electrode layer 120 is laminated on at least one main surface of the current collector 150 functioning as a counter electrode current collector, without the solid electrolyte layer 130 interposed therebetween. In the illustrated example, the current collectors 150 sandwiched between adjacent power generating elements 200 function as electrode current collectors, and the current collectors 150 located at the top and bottom function as counter electrode current collectors.

[0050] Each of the plurality of power generating elements 200 is sandwiched between two adjacent current collectors 150 among the plurality of current collectors 150. Furthermore, two adjacent power generating elements 200 among the plurality of power generating elements 200 are stacked with one of the plurality of current collectors 150 interposed therebetween.

[0051] The solid electrolyte layer 130 is in contact with each of the electrode layer 110 and the counter electrode layer 120. The thickness of the solid electrolyte layer 130 is, for example, not less than 5 μm and not more than 150 μm.

[0052] The solid electrolyte layer 130 includes at least a solid electrolyte and may include a binder material as needed. The solid electrolyte layer 130 may include a solid electrolyte having lithium ion conductivity.

[0053] As the solid electrolyte, known materials such as lithium ion conductors, sodium ion conductors, or magnesium ion conductors can be used. As the solid electrolyte, for example, a solid electrolyte material such as a sulfide solid electrolyte, a halogen-based solid electrolyte, or an oxide solid electrolyte can be used. As the sulfide solid electrolyte, for example, lithium sulfide (Li ２ S) and diphosphorus pentasulfide (P ２ S ５ ) is used. As the sulfide solid electrolyte, a mixture of Li ２ S-SiS ２ , Li ２ S-B ２ S ３ or Li ２ S-GeS ２Sulfides 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.

[0054] The oxide solid electrolyte may be, 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.

[0055] As the binder material, for example, elastomers are used, and organic compounds such as polyvinylidene fluoride, acrylic resin, or cellulose resin may also be used.

[0056] The electrode layer 110 is disposed on the main surface of the current collector 150, which functions as an electrode current collector, on the counter electrode layer 120 side. The electrode layer 110 is disposed opposite the counter electrode layer 120. The thickness of the electrode layer 110 is, for example, not less than 5 μm and not more than 300 μm, but is not limited thereto. Furthermore, the thickness of the electrode layer 110 is, for example, greater than a first thickness t1 of the current collector 150, which will be described later.

[0057] The electrode layer 110 includes at least a negative electrode active material and may include at least one of a solid electrolyte, a conductive additive, and a binder material as needed. Known materials capable of occluding and releasing (inserting and deintercalating, or dissolving and precipitating) lithium ions, sodium ions, or magnesium ions can be used as the negative electrode active material. Materials capable of occluding and intercalating lithium ions include, for example, carbon materials such as natural graphite, artificial graphite, graphite carbon fiber, and resin-baked carbon; metallic lithium; lithium alloys; and oxides of lithium and transition metal elements.

[0058] The solid electrolyte may be any of the above-described solid electrolyte materials. The conductive additive may be, for example, a conductive material such as acetylene black, carbon black, graphite, or carbon fiber. The binder may be any of the above-described binder materials.

[0059] The electrode layer 110 is produced by applying a paste-like paint, in which the materials contained in the electrode layer 110 are kneaded together with a solvent, onto the main surface of the current collector 150 and drying it. In order to increase the density of the electrode layer 110, the electrode plate including the electrode layer 110 and the current collector 150 may be pressed after drying.

[0060] The counter electrode layer 120 is disposed on the main surface of the current collector 150, which functions as a counter electrode current collector, on the electrode layer 110 side. The thickness of the counter electrode layer 120 is, for example, not less than 5 μm and not more than 300 μm, but is not limited thereto. The thickness of the counter electrode layer 120 is, for example, greater than a first thickness t1 of the current collector 150, which will be described later.

[0061] The counter electrode layer 120 contains at least a positive electrode active material, and may contain at least one of a solid electrolyte, a conductive additive, and a binder material, as necessary.

[0062] As the positive electrode active material, known materials capable of absorbing and releasing (inserting and desorbing, or dissolving and depositing) lithium ions, sodium ions, or magnesium ions can be used. As the positive electrode active material, in the case of a material capable of absorbing and inserting lithium ions, for example, lithium cobalt oxide composite oxide (LCO), lithium nickel oxide composite oxide (LNO), lithium manganese oxide composite oxide (LMO), lithium-manganese-nickel composite oxide (LMNO), lithium-manganese-cobalt composite oxide (LMCO), lithium-nickel-cobalt composite oxide (LNCO), or lithium-nickel-manganese-cobalt composite oxide (LNMCO) can be used.

[0063] The solid electrolyte may be the solid electrolyte material described above, the conductive additive may be the conductive material described above, and the binder may be the binder material described above.

[0064] The counter electrode layer 120 is produced by applying a paste-like paint, in which the materials contained in the counter electrode layer 120 are kneaded together with a solvent, onto the main surface of the current collector 150 and drying the paint. In order to increase the density of the counter electrode layer 120, the counter electrode plate including the counter electrode layer 120 and the current collector 150 may be pressed after drying.

[0065] In this embodiment, the electrode layer 110, the counter electrode layer 120, and the solid electrolyte layer 130 are maintained in the shape of parallel plates. This makes it possible to suppress the occurrence of cracks or collapse due to bending. Alternatively, the electrode layer 110, the counter electrode layer 120, and the solid electrolyte layer 130 may be smoothly curved together.

[0066] In the power generating element 200, for example, in a plan view, the current collector 150, the electrode layer 110, the counter electrode layer 120, and the solid electrolyte layer 130 each have the same shape and size, and when viewed from the z-axis direction, their outlines match.

[0067] The electrode layer 110 or the counter electrode layer 120 is in contact with a main surface of the current collector 150. The current collector 150 may include a current collector layer, which is a layer containing a conductive material, provided in a portion in contact with the electrode layer 110 or the counter electrode layer 120.

[0068] Known materials can be used as the material for the current collector 150. For example, the current collector 150 may be made of a foil, plate, or mesh-like material made of copper, aluminum, nickel, iron, stainless steel, platinum, gold, or an alloy of two or more of these metals. In the examples shown in FIGS. 1 to 3 , the current collector 150 is made of a single metal foil. The current collector 150 may have a multilayer structure of multiple current collecting layers made of multiple metal foils or the like. In this case, the multiple current collecting layers are stacked directly or via intermediate layers.

[0069] The current collector 150 has protrusions 151 that protrude on both sides in the stacking direction at the end on the side surface 160 side of the battery 100. The protrusions 151 are exposed at the side surface 160. At least a portion of the protrusions 151 is embedded in the power generating element 200 and overlaps with the power generating element 200 when viewed from the stacking direction. In the example shown, the entire protrusion 151 is embedded in the power generating element 200 and overlaps with the power generating element 200 when viewed from the stacking direction. The protrusions 151 cover a portion of the power generating element 200, specifically a portion of the electrode layer 110 or a portion of the counter electrode layer 120, at the side surface 160. The protrusions 151 are provided, for example, along the x-axis direction over the entire end of the current collector 150 on the side surface 160 side. The thickness of the current collector 150 other than the protrusions 151 is, for example, uniform. The current collector 150 may have the smallest thickness at its center.

[0070] Furthermore, the current collector 150 has a protruding portion 151, which increases the thickness of the end portion. Specifically, in a region where the current collector 150 and the power generating element 200 overlap when viewed along the stacking direction, the ratio of a second thickness t2, which is the maximum thickness at the end portion of the current collector 150 on the side surface 160 side, to a first thickness t1, which is the thickness at the center of the current collector 150, is 101% or more and 200% or less. This allows the end portion of the current collector 150 to sink into the electrode layer 110 or the counter electrode layer 120 and cover the end face of the power generating element 200, thereby preventing the electrode layer 110 or the counter electrode layer 120 covered by the end portion of the current collector 150 from collapsing. This prevents a short circuit between the electrode layer 110 and the counter electrode layer 120 due to collapse. Furthermore, because the second thickness t2 is 200% or less of the first thickness t1, the current collector 150 is less likely to come into contact with both the electrode layer 110 and the counter electrode layer 120 in one power generating element 200, and it is possible to prevent the current collector 150 from short-circuiting the electrode layer 110 and the counter electrode layer 120. This can improve the reliability of the battery 100. The second thickness t2 can also be said to be the maximum thickness (maximum length in the stacking direction) of the portion of the protruding portion 151 that overlaps with the power generating element 200 when viewed along the stacking direction.

[0071] The first thickness t1 is, for example, 5 μm or more and 100 μm or less. The second thickness t2 is, for example, 0.2 μm or more and 5 μm or less greater than the first thickness t1. This can enhance the effect of improving reliability due to the ratio of the second thickness t2 to the first thickness t1.

[0072] 1 to 3 , the end portion of the current collector 150 on the side surface 160 side is wider and thicker on both sides in the stacking direction than the central portion of the current collector 150. As a result, even if the second thickness t2 is thicker than the first thickness t1, the current collector 150 is less likely to come into contact with both the electrode layer 110 and the counter electrode layer 120 in one power generating element 200, making it less likely that a short circuit will occur between the electrode layer 110 and the counter electrode layer 120 via the current collector 150. Note that the portion of the protrusion 151 that protrudes upward at the top surface of the battery 100 and the portion that protrudes downward at the bottom surface may be removed by polishing or the like.

[0073] 1 and 2 , when the current collector 150 is viewed from the end of the side surface 160 of the current collector 150, that is, in a plan view relative to the side surface 160, the length of the end face of the current collector 150 in the stacking direction is not constant. In other words, the thickness (length in the stacking direction) of the protrusion 151 is not constant. As a result, the thicker portions of the protrusion 151 act as catches, making it difficult for the current collector 150 and the power-generating element 200 to slide in a direction perpendicular to the stacking direction, thereby preventing peeling between the current collector 150 and the power-generating element 200. Furthermore, in a plan view relative to the side surface 160, the boundary between the current collector 150 and the power-generating element 200 is uneven, e.g., wavy. Specifically, the boundary between the current collector 150 and the power-generating element 200 is the boundary between the current collector 150 and the electrode layer 110 or the boundary between the current collector 150 and the counter electrode layer 120.

[0074] The side surface 160 of the battery 100 is, for example, a cut surface that has been subjected to a finishing cutting process. The shape of the end portion of the current collector 150 on the side surface 160 side is formed by the cutting process. The cutting process will be described in detail later.

[0075] When the current collector 150 is viewed from the end of the current collector 150 on the side of the side surface 160, that is, in a plan view of the side surface 160, a linear pattern 150a, which is an example of a linear recess or protrusion, is provided on the end surface of the current collector 150. The end surface of the current collector 150 constitutes a part of the side surface 160. The linear pattern 150a is, for example, a minute linear depression or protrusion on the end surface caused by a cutting process. In the example shown in FIG. 2, multiple linear patterns 150a are provided on the end surface of the current collector 150. The multiple linear patterns 150a may be a mixture of depressions and protrusions. The angle that the linear patterns 150a form with respect to the stacking direction is 90°. The angle of 90° means that the angle is substantially 90°, and may include an error of 5% or less. By providing the linear pattern 150a on the end surface of the current collector 150, when a terminal is connected to the end surface, the terminal is caught on the linear pattern 150a, making it less likely for the terminal to shift in the stacking direction, thereby preventing a short circuit between the electrode layer 110 and the counter electrode layer 120 via the terminal.

[0076] On the side surface 160, for example, the end face of the current collector 150 and the portion of the end face of the power generating element 200 that is not covered by the current collector 150 are flush with each other without any steps. Note that on the side surface 160, the current collector 150 may protrude slightly beyond the power generating element 200.

[0077] [Method for Manufacturing Battery] Next, a method for manufacturing the battery 100 according to this embodiment will be described.

[0078] 4 is a flowchart showing an example of a method for manufacturing the battery 100 according to this embodiment. Note that the method for manufacturing the battery 100 described below is just an example, and the method is not limited to the following method as long as the battery 100 can be manufactured.

[0079] First, a laminate 300 is prepared in which the power generating element 200 and the current collector 150 are laminated (step S11).Then, the laminate 300 is cut to form the cut surface 160a (step S12).

[0080] Fig. 5 is a perspective view showing the state after the laminate 300 has been cut. Fig. 6 is a cross-sectional view of the laminate 100a remaining after cutting the laminate 300. Fig. 6 is a cross-sectional view of the laminate 100a when the laminate 100a is cut parallel to the stacking direction (z-axis direction) and perpendicular to the cutting surface 160a.

[0081] As shown in Fig. 5 , the laminate 300 has a plurality of power generating elements 200 and a plurality of current collectors 150. The layer structure and layer order of the laminate 300 are the same as those of the battery 100 described above. In step S11, the laminate 300 having the layer structure and layer order shown in Fig. 5 is prepared. The laminate 300 is formed, for example, by stacking coated plates in which the materials of each layer are coated on current collectors 150.

[0082] 5, the cut surface 160a is formed by cutting the laminate 300 so as to collectively cut the plurality of power generating elements 200 and the plurality of current collectors 150. Therefore, in the cutting in step S12, the laminate 300 is cut along the stacking direction at a position that passes through the two upper and lower main surfaces of the laminate 300.

[0083] Furthermore, in the cutting in step S12, for example, the laminate 300 is cut by shearing the laminate 300 with the cutting blade 500. In the example shown in FIG. 5 , the laminate 300 is cut by moving the cutting blade 500 from above the main surface of the laminate 300 along the stacking direction. That is, when the laminate 300 is used as a reference, the cutting blade 500 passes through the two main surfaces, upper and lower, of the laminate 300 and moves in a direction parallel to the stacking direction of the laminate 300. When cutting the laminate 300, for example, the cutting blade 500 is moved, but the laminate 300 may also be moved. Note that when the laminate 300 is used as a reference, the cutting blade 500 may pass through the two main surfaces, upper and lower, of the laminate 300 and move in a direction inclined or perpendicular to the stacking direction of the laminate 300.

[0084] By cutting the laminate 300, a laminate 100a having a cut surface 160a as an end surface is formed. In step S12, the laminate 300 may be cut to remove an end portion of the laminate 300, or the laminate 300 may be divided to form a plurality of laminates 100a.

[0085] Cutting the laminate 300 crushes each layer of the power-generating element 200, causing the electrode layer 110, the counter electrode layer 120, and the solid electrolyte layer 130 to collapse. Furthermore, as shown in FIG. 6 , a hanging portion 152 that can cause a short circuit between the electrode layer 110 and the counter electrode layer 120 is formed at the end of the current collector 150 on the cut surface 160a side of the laminate 100a. The hanging portion 152 is, for example, a burr, and is formed when tensile stress is applied to the end of the current collector 150 due to shearing. The hanging portion 152 formed by cutting the laminate 300 is not embedded in the end face of the power-generating element 200 but extends in the stacking direction along the end face of the power-generating element 200. The hanging portion 152 may extend 5 μm or more in the stacking direction in the current collector 150. Furthermore, the hanging portion 152 extends only in one direction in the stacking direction at the end of the current collector 150. The extending direction of hanging portion 152 is the direction in which cutting blade 500 advances relative to laminate 300. In laminate 100a, collapse of hanging portion 152, electrode layer 110, counter electrode layer 120, and solid electrolyte layer 130 increases the likelihood of a short circuit occurring between electrode layer 110 and counter electrode layer 120. Therefore, in the present embodiment, the collapsed portions of hanging portion 152, electrode layer 110, counter electrode layer 120, and solid electrolyte layer 130 are removed by a cutting process described below.

[0086] Next, as a cutting process, the cut surface 160a of the laminate 100a is cut (step S13). At this time, the end faces of each layer of the power-generating element 200 and the end face of the current collector 150 at the cut surface 160a are entirely cut at once. This results in a battery 100 having cut surfaces formed as the side surfaces 160. After the cutting process, the side surfaces 160 may be polished and / or cleaned.

[0087] Fig. 7 is a perspective view illustrating the cutting process. Fig. 7 shows the battery 100 formed by cutting the cut surface 160a of the laminate 100a. Note that Fig. 7 does not show the linear pattern 150a shown in Fig. 2.

[0088] The cutting in step S13 differs from cutting in that it is a process of scraping off a certain surface by a small thickness. The thickness of the portion scraped off by cutting is 10 μm or less. On the other hand, in cutting in step S12, even when cutting off the end of the laminate 300, the thickness of the portion to be cut off exceeds 10 μm, for example, 1 mm or more. Furthermore, the cutting in step S12 and the cutting in step S13 are performed using different devices.

[0089] In the cutting process, the cut surface 160a of the laminate 100a is cut with a cutting blade 600 at an angle of 90° relative to the stacking direction, forming a cut surface as the side surface 160. The angle of 90° means that the angle is essentially 90°, and may include an error of 5% or less. The cutting blade 600 may be, for example, a metal blade such as a razor blade or a ceramic blade. The cutting blade 600 may be, for example, a single-edged blade with a cutting edge on only one side. The cutting blade 600 is used, for example, with the non-angled side of the blade of the single-edged blade facing the cutting surface 160a.

[0090] For example, the cutting blade 600 is fixed so that the surface of the cut surface 160a of the laminate 100a can be traced over the cutting blade 600 in a direction 90° to the stacking direction, and then the cutting depth of the cutting blade 600 is gradually increased, causing the cutting blade 600 to penetrate into the cut surface 160a of the laminate 100a. In this manner, the cutting blade 600 cuts the cut surface 160a of the laminate 100a while pressing the cut surface 160a against the cutting blade 600. Note that as long as the cutting edge of the cutting blade 600 is pressed against the cut surface 160a and moves along the cut surface 160a in a direction 90° to the stacking direction, the surface of the cutting blade 600 facing the cut surface 160a does not need to be parallel to the cut surface 160a. For example, when the cutting edge of the cutting blade 600 is pressed against the cut surface 160a, the surface of the cutting blade 600 facing the cut surface 160a may be inclined with respect to the cut surface 160a.

[0091] When cutting the cut surface 160a, microscopic plastic flow occurs in the structure of the current collector 150, causing the structure of the current collector 150 near the cut surface 160a to escape in the stacking direction. As a result, the end of the current collector 150 protrudes in the stacking direction, forming a protrusion 151, and the thickness of the end of the current collector 150 increases. Furthermore, the plastically flowed structure of the current collector 150 sinks into the end face of the power generating element 200. This makes it difficult for the plastically flowed structure of the current collector 150 to grow in the stacking direction. Furthermore, because the cutting blade 600 is pressed against the cut surface 160a, the sinking of the plastically flowed structure of the current collector 150 can be increased. Furthermore, fluctuations are likely to occur in the microscopic plastic flow of the structure of the current collector 150 that occurs as the cutting blade 600 advances, and the boundary between the current collector 150 and the power generating element 200 is not straight, but rather has a tortuous unevenness at the boundary. In this way, an end structure such as a protrusion 151 on the side surface 160 of the current collector 150 is formed on the current collector 150. Unlike the hanging portion 152 generated by the cutting in step S12, the protrusion 151 extends on both sides in the stacking direction, and therefore is less likely to become excessively long in the stacking direction, and this can also prevent short circuits from occurring between the electrode layer 110 and the counter electrode layer 120. Note that if the protrusion 151 is not recessed into the power generating element 200, the protrusion 151 may be pressed against the power generating element 200 to cause it to recess into the power generating element 200.

[0092] Furthermore, because the cut surface 160a is cut in a direction at an angle of 90 degrees to the stacking direction, it is possible to weaken the force applied at the cut surface 160a in the stacking direction, which is the direction that would peel off the layers of the power generating element 200 and the current collector 150. This reduces damage to the battery 100 during manufacturing.

[0093] Furthermore, by cutting the cut surface 160a along a direction at an angle of 90° to the stacking direction, linear patterns 150a (see FIG. 2 ) that form an angle of 90° with the stacking direction can be formed as cutting marks on the end surface of the current collector 150. Even when cutting marks are formed on the end surface of the current collector 150, the force applied to the current collector 150 in forming the cutting marks is in a direction at an angle of 90° with respect to the stacking direction, and so force is unlikely to be applied in the stacking direction, which is a direction that would peel the power generating element 200 and the current collector 150 apart.

[0094] The manufacturing method described above makes it possible to realize the battery 100 having the above-described structure and to manufacture a highly reliable battery 100. Furthermore, by performing the cutting process, the end face positions of the layers of the battery 100 can be aligned, and the electrode layer 110 and the counter electrode layer 120 do not protrude from the side surface 160 of the battery 100, thereby suppressing short circuits due to contact between the electrode layer 110 and the counter electrode layer 120.

[0095] Furthermore, the ends of the laminate 300 formed by coating are unlikely to function as a battery, and cutting the ends of the laminate 300 can increase the capacity density of the battery 100 to be manufactured. Cutting the laminate 300 to a desired size can also improve the capacity precision of the battery 100. On the other hand, cutting the laminate 300 increases the likelihood of a short circuit occurring between the electrode layer 110 and the counter electrode layer 120 due to the collapse of the hanging portion 152, the electrode layer 110, the counter electrode layer 120, and the solid electrolyte layer 130. Cutting the cut surface 160a formed by cutting the laminate 300 can remove the collapsed portions of the hanging portion 152, the electrode layer 110, the counter electrode layer 120, and the solid electrolyte layer 130, thereby enabling the manufacture of a highly reliable battery 100.

[0096] In the above-described method for manufacturing the battery 100, cutting the laminate 300 in step S12 is not essential, and for example, cutting processing may be performed on the end faces of the laminate 300 in step S13.

[0097] Furthermore, in manufacturing the battery 100, for example, the side surface 160 of the current collector 150 may be made to slightly protrude beyond the power-generating element 200, and the protruding portion of the current collector 150 may be stretched in the stacking direction and pressed against the power-generating element 200 to form the protruding portion 151. In this case, the above-described steps S12 and S13 may not be performed.

[0098] While the battery and the method for manufacturing the battery 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 that a person skilled in the art can make 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.

[0099] For example, in the above embodiment, among the ends of the current collector 150, only the end of the current collector 150 on one side surface 160 of the battery 100 is thicker than the central portion, but this is not limited to this. The end of the current collector 150 on the side surface of the battery 100 other than side surface 160 may also be provided with a protrusion 151 and may be thicker than the central portion, similar to the end of the current collector 150 on the side surface 160.

[0100] Furthermore, in the above embodiment, the formation of one side surface 160 of the battery 100 has been described, but side surfaces other than the side surface 160 of the battery 100 may also be formed in the same manner as the side surface 160. For example, all side surfaces of the battery 100 may be machined surfaces formed by the above manufacturing method.

[0101] Furthermore, in the above embodiment, the plurality of power generating elements 200 in the battery 100 are stacked so as to be electrically connected in parallel, but this is not limited thereto. The plurality of power generating elements 200 may also be stacked so as to be electrically connected in series. In this case, the plurality of power generating elements 200 are stacked side by side along the z-axis so that the arrangement order of the layers constituting the power generating elements 200 is the same. In other words, adjacent power generating elements 200 are stacked so that opposite poles are electrically connected to each other. Furthermore, the current collector 150 located between adjacent power generating elements 200 functions as a bipolar current collector.

[0102] Furthermore, the above-described embodiments can be modified, substituted, added, omitted, and the like in various ways within the scope of the claims or their equivalents.

[0103] The batteries according to the present disclosure can be used as batteries in electronic devices, electrical appliances, electric vehicles, and the like.

[0104] REFERENCE SIGNS LIST 100 Battery 100a, 300 Laminate 110 Electrode layer 120 Counter electrode layer 130 Solid electrolyte layer 150 Current collector 150a Linear pattern 151 Protruding portion 152 Hanging portion 160 Side surface 160a Cut surface 200 Power generating element 500 Cutting blade 600 Cutting blade

Claims

1. A battery comprising: a power generating element; and a current collector laminated on the power generating element, wherein in a region where the current collector and the power generating element overlap when viewed along the lamination direction of the power generating element and the current collector, a ratio of a second thickness which is the maximum thickness at an end of the current collector to a first thickness which is the thickness at the center of the current collector is 101% or more and 200% or less.

2. The battery according to claim 1, wherein the second thickness is greater than the first thickness by 0.2 μm or more and 5 μm or less.

3. The battery according to claim 1, wherein when the current collector is viewed from the end side, the length of the end face of the current collector in the stacking direction is not constant.

4. The battery according to claim 1, wherein the ends of the current collector extend further on both sides in the stacking direction than the central portion of the current collector.

5. The battery according to claim 1, wherein, when the current collector is viewed from the end side, a linear recess or protrusion is provided on the end face of the current collector, and the angle that the linear recess or protrusion makes with the stacking direction is 90°.

6. The battery according to any one of claims 1 to 5, wherein the power generating element has a positive electrode layer, a negative electrode layer, and a solid electrolyte layer located between the positive electrode layer and the negative electrode layer.

7. A method for manufacturing a battery, comprising: a step of preparing a laminate in which a power generating element and a current collector are stacked; and a step of cutting an end face of the laminate in a direction at 90° to the stacking direction of the power generating element and the current collector.

8. The method for manufacturing a battery according to claim 7, wherein in the cutting step, the end face of the laminate is cut with a cutting blade while the end face is pressed against the cutting blade.

9. The method for manufacturing a battery according to claim 7 or 8, further comprising a step of forming cut surfaces as the end faces by cutting the laminate before the cutting step.

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