Energy storage device and method for manufacturing the same

Abstract

To provide a highly reliable energy storage device and a method for manufacturing the same. [Solution] In a method for manufacturing an energy storage device, one of the horn and anvil has a first projection on the surface that contacts the first outer surface of the first electrode tab group, and the other of the horn and anvil has a first region and a second region on the surface that contacts the second outer surface of the first electrode tab group, the second region is formed around the first region and a plurality of second projections are formed in the second region, the first region is formed flat, or a third projection is formed in the first region and the height of the third projection is lower than the height of the second projection, or a third projection is formed in the first region and (total area of ​​the third projection in plan view / area of ​​the first region in plan view) is smaller than (total area of ​​the second projection in plan view / area of ​​the second region in plan view), and in the process of forming a joint, the first projection and the first region face each other across the first electrode tab group, the first projection contacts the first outer surface of the first electrode tab group, and vibration is applied while the first region and the plurality of second projections are in contact with the second outer surface of the first electrode tab group.

Description

[Technical Field]

[0001] This technology relates to an energy storage device and a method for manufacturing the same. [Background technology]

[0002] Japanese Patent Publication No. 2019-126822 (Patent Document 1) discloses a method for applying ultrasonic vibrations to a workpiece placed on an anvil while pressing a horn against it, in which the workpiece is not brought into contact with the joint between the main body of the horn and a plurality of protrusions. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2019-126822 [Overview of the project] [Problems that the invention aims to solve]

[0004] In energy storage devices, conductive connection parts are formed. Improving the reliability of these conductive connection parts is required. From this perspective, the battery described in Japanese Patent Publication No. 2021-51597 still has room for improvement.

[0005] The objective of this technology is to provide a highly reliable energy storage device and a method for manufacturing the same. [Means for solving the problem]

[0006] This technology provides the following energy storage devices and methods for manufacturing the same.

[0007] [1] A method for manufacturing an energy storage device comprising an electrode body including a first electrode and a second electrode, wherein the electrode body has a group of first electrode tabs in which a plurality of first electrode tabs connected to the first electrode are stacked, and the group of first electrode tabs includes a first outer surface and a second outer surface located on opposite sides of each other, comprising the steps of manufacturing an electrode body having the group of first electrode tabs, and forming a joint portion in the group of first electrode tabs where the first electrode tabs are joined together by applying vibration to the group of first electrode tabs with the horn while the group of first electrode tabs is sandwiched between a horn and an anvil in the stacking direction of the first electrode tabs, wherein one of the horn and the anvil has a first projection on the surface that abuts the first outer surface of the group of first electrode tabs, and the other of the horn and the anvil has a first projection on the surface that abuts the second outer surface of the group of first electrode tabs A method for manufacturing an energy storage device, comprising: having a first region and a second region, wherein the second region is formed around the first region, a plurality of second protrusions are formed in the second region, the first region is formed flat, or a third protrusion is formed in the first region and the height of the third protrusion is lower than the height of the second protrusion, or a third protrusion is formed in the first region and (total area of ​​the third protrusion in plan view / area of ​​the first region in plan view) is smaller than (total area of ​​the second protrusion in plan view / area of ​​the second region in plan view), and in the step of forming the joint, the first protrusion and the first region face each other with the first electrode tab group in between, the first protrusion abuts the first outer surface of the first electrode tab group, and the vibration is applied while the first region and the plurality of second protrusions abut the second outer surface of the first electrode tab group.

[0008] [2] The method for manufacturing an energy storage device according to [1], wherein the first region is a flat region.

[0009] [3] The method for manufacturing an energy storage device according to [1] or [2], wherein the second region is formed to surround the first region.

[0010] [4] The method for manufacturing an energy storage device according to [3], wherein the second region is formed in an annular shape.

[0011] [5] The method for manufacturing an energy storage device according to any one of [1] to [4], wherein the first projection is linear.

[0012] [6] The method for manufacturing an energy storage device according to any one of [1] to [5], wherein the first projection includes a plurality of linearly formed projections extending in substantially the same direction from one another.

[0013] [7] The method for manufacturing an energy storage device according to any one of [1] to [6], wherein the joint portion includes a first joint region formed in the region in which the first projection abuts, and a second joint region formed around the first joint region.

[0014] [8] A method for manufacturing an energy storage device according to any one of [1] to [7], further comprising the step of joining the joint portion in the first electrode tab group to the first conductive member after the step of forming the joint portion.

[0015] [9] A method for manufacturing an energy storage device according to [8], wherein the first conductive member is brought into contact with the second outer surface of the first electrode tab group, and an energy ray is irradiated onto the joint from the first outer surface side to join the joint in the first electrode tab group and the first conductive member.

[0016]

[10] An electric storage device includes an electrode body including a first electrode and a second electrode, and a first conductive member electrically connected to the electrode body. The electrode body includes a first electrode tab group in which a plurality of first electrode tabs connected to the first electrode are stacked. The first electrode tab group includes a first outer surface and a second outer surface located on opposite sides of each other. A plurality of first recesses are formed on the first outer surface. The second outer surface has a first region and a second region. The second region is formed around the first region. A plurality of second recesses are formed in the second region. The first region is formed flat, or a third recess is formed in the first region, and the depth of the third recess is formed shallower than the depth of the second recess, or a third recess is formed in the first region, and (the total area of the third recesses in plan view / the area of the first region in plan view) is smaller than (the total area of the second recesses in plan view / the area of the second region in plan view). When the first electrode tab group is viewed from the stacking direction of the first electrode tabs, the first recesses are disposed at positions overlapping the first region.

[0017]

[11] The electric storage device according to

[10] , wherein the first region is a flat region.

[0018]

[12] The electric storage device according to

[10] or

[11] , wherein the first conductive member is joined to the first region of the second outer surface.

[0019]

[13] The electric storage device according to any one of

[10] to

[12] , wherein the second region is formed so as to surround the first region.

[0020]

[14] The electric storage device according to

[13] , wherein the second region is formed in an annular shape.

[0021]

[15] The electric storage device according to any one of

[10] to

[14] , wherein the first recesses are formed linearly.

Advantages of the Invention

[0022] According to the present technology, a highly reliable electric storage device and a method for manufacturing the same can be provided.

Brief Description of the Drawings

[0023] [Figure 1] It is a front view showing the configuration of the secondary battery according to the embodiment. [Figure 2] It is a view showing the state of the secondary battery shown in FIG. 1 as viewed from the direction of arrow II. [Figure 3] It is a view showing the state of the secondary battery shown in FIG. 1 as viewed from the direction of arrow III. [Figure 4] It is a view showing the state of the secondary battery shown in FIG. 1 as viewed from the direction of arrow IV. [Figure 5] It is a view showing the state of the secondary battery shown in FIG. 1 as viewed from the direction of arrow V. [Figure 6] It is a front cross-sectional view of the secondary battery shown in FIG. 1. [Figure 7] It is a cross-sectional view of the negative electrode plate. [Figure 8] It is a front view showing the negative electrode plate. [Figure 9] It is a cross-sectional view of the positive electrode plate. [Figure 10] It is a front view showing the positive electrode plate. [Figure 11] It is an XI-XI cross-sectional view of the secondary battery shown in FIG. 1. [Figure 12] It is an XII-XII cross-sectional view of the secondary battery shown in FIG. 1. [Figure 13] It is a flowchart showing a method for manufacturing a secondary battery according to one embodiment. [Figure 14] It is a perspective view showing the state before two electrode bodies included in the secondary battery according to one embodiment overlap. [Figure 15] It is an XV-XV cross-sectional view of the electrode body and the current collector shown in FIG. 14. [Figure 16] It is a perspective view showing the state in which a holder and a spacer are attached to the electrode body. [Figure 17] It is a perspective view showing the state in which a sealing plate is attached to the current collector on the negative electrode side. [Figure 18] It is an XVIII-XVIII cross-sectional view of the electrode body and the current collector shown in FIG. 17. [Figure 19]This is a perspective view showing the positive electrode current collector with a sealing plate attached. [Figure 20] This is a perspective view showing the configuration of a secondary battery. [Figure 21] This diagram shows the process of joining electrode tabs together using a horn and an anvil. [Figure 22] This figure shows an example of horn placement during the electrode tab bonding process. [Figure 23] This diagram shows the arrangement of the horn and anvil during the electrode tab bonding process. [Figure 24] This is a perspective view of the horn. [Figure 25] This is a plan view showing the arrangement of the horns at the joint. [Figure 26] This is a plan view showing the arrangement of anvils at the joint. [Figure 27] This figure shows a group of electrode tabs joined together by a horn and anvil. [Figure 28] This diagram shows the area around the junction in the electrode tab group. [Figure 29] This is a cross-sectional view from XXIX-XXIX in Figure 28. [Figure 30] This is a cross-sectional view taken along the line XXX-XXX in Figure 28. [Figure 31] This is a cross-sectional view showing the joint. [Figure 32] This is a cross-sectional view showing another example of a joint. [Figure 33] This is a cross-sectional view showing yet another example of a joint. [Figure 34] This is a plan view (part 1) showing a modified arrangement of anvils at the joint. [Figure 35] This is a plan view (part 2) showing a modified arrangement of anvils at the joint. [Modes for carrying out the invention]

[0024] Embodiments of this technology are described below. Note that the same or corresponding parts may be denoted by the same reference numerals, and their descriptions may not be repeated.

[0025] In the embodiments described below, when referring to the number, quantity, etc., unless otherwise specified, the scope of this technology is not necessarily limited to that number, quantity, etc. Also, in the embodiments described below, each component is not necessarily essential to this technology unless otherwise specified. Furthermore, this technology is not necessarily limited to achieving all of the effects and advantages mentioned in these embodiments.

[0026] In this specification, the terms "comprise," "include," and "have" are in open-ended form. That is, if a configuration includes one configuration, it may also include other configurations, or it may not.

[0027] Furthermore, where geometric terms and terms describing positional and directional relationships are used in this specification, such as "parallel," "orthogonal," "45° oblique," "coaxial," and "alongside," these terms allow for manufacturing tolerances or slight variations. Where terms describing relative positional relationships, such as "upper" and "lower," are used in this specification, these terms are used to indicate the relative positional relationship in a single state, and the relative positional relationship may be reversed or rotated to any angle depending on the installation direction of each mechanism (for example, by inverting the entire mechanism upside down).

[0028] Furthermore, the dimensions of each component illustrated in this specification, such as width, length, and diameter, are not limited to those shown and may be changed as appropriate. In this specification, each component may be assigned an ordinal number such as "1st" or "2nd," but these ordinal numbers do not limit priority, order, etc., unless explicitly specified.

[0029] In this specification, "battery" is not limited to lithium-ion batteries, but may include other batteries such as nickel-metal hydride batteries and sodium-ion batteries. In this specification, "electrode" may refer collectively to the positive electrode and the negative electrode. Also, "electrode plate" may refer collectively to the positive electrode plate and the negative electrode plate.

[0030] In this specification, when the terms “energy storage device,” “energy storage cell,” or “energy storage module” are used, “energy storage device,” “energy storage cell,” or “energy storage module” are not limited to batteries, battery cells, or battery modules, but may include capacitors, capacitor cells, or capacitor modules.

[0031] "Battery cells" can be installed in hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and battery electric vehicles (BEVs). However, the use of "battery cells" is not limited to automotive applications.

[0032] In this specification, the X direction may be referred to as the "width direction" of the secondary battery, electrode body, and case body, the Z direction may be referred to as the "height direction" of the secondary battery or case body, and the Y direction may be referred to as the "thickness direction" of the secondary battery or case body.

[0033] (Overall configuration of a secondary battery) The overall configuration of the secondary battery 1 will be described with reference to Figures 1 to 6. The secondary battery 1 includes a case 100, an electrode body 200, electrode terminals 300, and a current collector 400. The case 100 includes a case body 110, a sealing plate 120, and a sealing plate 130.

[0034] When a battery pack including a secondary battery 1 is constructed, multiple secondary batteries 1 are stacked in the thickness direction. The stacked secondary batteries 1 may be constrained in the stacking direction (Y direction) by a restraining member to form a battery module, or the battery pack may be directly supported on the side of the battery pack case without using a restraining member.

[0035] The case body 110 consists of a cylindrical, preferably rectangular, member. This results in a rectangular secondary battery 1. The case body 110 is made of metal. Specifically, the case body 110 is made of aluminum, aluminum alloy, iron, or iron alloy.

[0036] As shown in Figures 1 and 2, sealing plates 120 and 130 are provided at both ends of the case body, respectively. The case body 110 can be formed into a rectangular tube shape by, for example, bringing together the ends of bent plate-like members (joint portion 115 as illustrated in Figure 2) and joining them together (for example, by energy ray irradiation such as laser welding). The corners of the "rectangular tube" may have a rounded shape. The secondary battery in this technology is not necessarily limited to a prismatic secondary battery.

[0037] In this embodiment, the case body 110 is formed to be longer in the width direction (X direction) of the secondary battery 1 than in the thickness direction (Y direction) and height direction (Z direction) of the secondary battery 1. The dimension (width) of the case body 110 in the X direction is preferably about 30 cm or more. This makes it possible to construct a relatively large (high capacity) secondary battery 1. The dimension (height) of the case body 110 in the Z direction is preferably about 20 cm or less, more preferably about 15 cm or less, and even more preferably about 10 cm or less. This makes it possible to construct a relatively low-height secondary battery 1, which improves, for example, its mountability in a vehicle.

[0038] The case body 110 includes a pair of first side sections 111 and a pair of second side sections 112. The pair of first side sections 111 constitute a part of the side surface of the case 100. The pair of second side sections 112 constitute the bottom and top surfaces of the case 100. Each of the pair of first side sections 111 and the pair of second side sections 112 is provided so as to intersect each other. The pair of first side sections 111 and the pair of second side sections 112 are connected at their respective ends. It is desirable that each of the pair of first side sections 111 has a larger area than each of the pair of second side sections 112.

[0039] As shown in Figure 5, a gas exhaust valve 150 is provided on one of the pair of second side portions 112A. The gas exhaust valve 150 extends in the width direction (X direction) of the secondary battery 1. The gas exhaust valve 150 extends in the X direction to the extent that it does not reach the ends of the case body 110 from the center in the X direction. The shape of the gas exhaust valve 150 can be changed as appropriate.

[0040] The thickness of the plate-shaped member in the gas discharge valve 150 is thinner than the thickness of the other plate-shaped members in the case body 110. As a result, when the pressure inside the case 100 exceeds a predetermined value, the gas discharge valve 150 preferentially ruptures compared to other parts of the case body 110, and discharges the gas inside the case 100 to the outside.

[0041] As shown in Figure 2, a joint portion 115 is formed on the other second side portion 112B of the pair of second side portions 112. The joint portion 115 extends in the width direction (X direction) of the secondary battery 1. At the joint portion 115, the ends of the plate-shaped members constituting the case body 110 are joined together.

[0042] As shown in Figure 3, an opening 113 (first opening) is provided at one end of the case body 110 in the first direction (X direction). The opening 113 is sealed by a sealing plate 120 (first sealing plate). A joint 115 is formed in the opening 113 to seal it. The opening 113 and the sealing plate 120 have a substantially rectangular shape with the Y direction being the short side and the Z direction being the long side. The substantially rectangular shape includes a rectangular shape, or a rectangular shape with rounded corners, etc.

[0043] A negative electrode terminal 301 (first electrode terminal) is provided on the sealing plate 120. The position of the negative electrode terminal 301 can be changed as appropriate.

[0044] As shown in Figure 4, an opening 114 (second opening) is provided at the end of the case body 110 opposite to the first side in the X direction. That is, the opening 114 is located at the end opposite to the opening 113, and the openings 113 and 114 face each other. The opening 114 is sealed by a sealing plate 130 (second sealing plate). A joint 115 is formed in the opening 114 to seal it. The opening 114 and the sealing plate 130 have a substantially rectangular shape with the Y direction being the short side and the Z direction being the long side.

[0045] A positive electrode terminal 302 (second electrode terminal) and an electrolyte injection hole 134 are provided on the sealing plate 130. The electrolyte injection hole 134 only needs to be large enough to inject electrolyte into the case 100, and is preferably smaller than the insertion hole for the positive electrode terminal 302 provided on the sealing plate 130. It is preferable that the electrolyte injection hole 134 is offset from the center of the sealing plate 130 in the Z direction. The positions of the positive electrode terminal 302 and the electrolyte injection hole 134 can be changed as appropriate.

[0046] The sealing plates 120 and 130 are made of metal. Specifically, the sealing plates 120 and 130 are made of aluminum, aluminum alloy, iron, or iron alloy, etc.

[0047] The negative electrode terminal 301 is electrically connected to the negative electrode (first electrode) of the electrode body 200. The negative electrode terminal 301 is attached to the sealing plate 120, i.e., the case 100.

[0048] The positive terminal 302 is electrically connected to the positive electrode (second electrode) of the electrode body 200. The positive terminal 302 is attached to the sealing plate 130, i.e., the case 100.

[0049] The negative electrode terminal 301 is made of a conductive material (more specifically, a metal), such as copper or a copper alloy. A portion or layer made of aluminum or an aluminum alloy may be provided on the outer surface of the negative electrode terminal 301.

[0050] The positive terminal 302 is made of a conductive material (more specifically, a metal), which may be made of aluminum or an aluminum alloy, for example.

[0051] The injection hole 134 is sealed by a sealing member (not shown). For example, a blind rivet or other metal member can be used as the sealing member.

[0052] The electrode body 200 is a flat-shaped electrode body in which negative electrode plates and positive electrode plates, described later, are stacked. Specifically, the electrode body 200 is a laminated electrode body in which a plurality of negative electrode plates and a plurality of positive electrode plates are alternately stacked with a separator in between. The separator may be a strip-shaped insulating sheet member folded in a zigzag pattern, or it may be a plurality of separate insulating sheets provided individually. In this specification, "electrode body" is not limited to a laminated electrode body, and may also be a wound electrode body in which a strip-shaped negative electrode plate and a strip-shaped positive electrode plate are wound together with a strip-shaped separator in between. The separator can be made of, for example, a polyolefin microporous film. When the electrode body is a laminated electrode body including a plurality of negative electrode plates and a plurality of positive electrode plates, negative electrode tabs (first electrode tabs) provided on each negative electrode plate can be stacked to form a negative electrode tab group, and positive electrode tabs (second electrode tabs) provided on each positive electrode plate can be stacked to form a positive electrode tab group.

[0053] As shown in Figure 6, the case 100 houses the electrode body 200. In Figure 6, the first electrode body 201, which will be described later, is shown as an example. The first electrode body 201 is housed in the case 100 so that its longitudinal direction is parallel to the X direction.

[0054] Specifically, one or more laminated electrode bodies are housed inside the insulating sheet 700 (described later) placed within the case 100, together with an electrolyte (not shown). As the electrolyte (non-aqueous electrolyte), for example, a non-aqueous solvent prepared by mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio (25°C) of 30:30:40, in which LiPF6 is dissolved at a concentration of 1.2 mol / L can be used. A solid electrolyte may be used instead of an electrolyte.

[0055] The electrode body 200 includes a first electrode body 201. The first electrode body 201 includes a substantially rectangular main body, a negative electrode tab group 220, and a positive electrode tab group 250.

[0056] The main body is composed of a negative electrode plate 210 and a positive electrode plate 240, which will be described later. The negative electrode tab group 220 is located at one end (sealing plate 120 side) of the first electrode body 201 in the X direction relative to the main body. The positive electrode tab group 250 is located at the other end (sealing plate 130 side) of the first electrode body 201 in the X direction relative to the main body.

[0057] The negative electrode tab group 220 and the positive electrode tab group 250 are formed to protrude from the central portion of the electrode body 200 toward the sealing plate 120 or the sealing plate 130, respectively.

[0058] The current collector 400 includes a negative electrode current collector 400A and a positive electrode current collector 400B. The negative electrode current collector 400A and the positive electrode current collector 400B are each made of plate-shaped members. The electrode body 200 is electrically connected to the negative electrode terminal 301 and the positive electrode terminal 302 via the current collector 400.

[0059] The negative electrode current collector 400A is positioned on the sealing plate 120 via a resin insulating member. The negative electrode current collector 400A is electrically connected to the negative electrode tab group 220 and the negative electrode terminal 301. The negative electrode current collector 400A is made of a conductive material (more specifically, a metal), which may be made of copper or a copper alloy, for example. Details of the negative electrode current collector 400A will be described later.

[0060] The positive electrode current collector 400B is positioned on the sealing plate 130 via a resin insulating member. The positive electrode current collector 400B is electrically connected to the positive electrode tab group 250 and the positive electrode terminal 302. The positive electrode current collector 400B is made of a conductive material (more specifically, a metal), such as aluminum or an aluminum alloy. The positive electrode tab group 250 may be electrically connected to the sealing plate 130 directly or via the positive electrode current collector 400B. In this case, the sealing plate 130 may also function as the positive electrode terminal 302. Details of the positive electrode current collector 400B will be described later.

[0061] (Configuration of electrode body 200) As shown in Figures 7 and 8, a negative electrode tab 230, consisting of a negative electrode core 211, is provided at one end of the negative electrode plate 210 in the width direction. When the negative electrode plates 210 are stacked, multiple negative electrode tabs 230 are stacked to form a negative electrode tab group 220. The negative electrode tab group 220 is electrically connected to the negative electrode. The length of each negative electrode tab 230 in the protruding direction on the multiple negative electrode plates 210 is appropriately adjusted considering the state in which the negative electrode tab group 220 is connected to the negative electrode current collector 400A. The shape of the negative electrode tab 230 is not limited to that illustrated in Figure 8.

[0062] As shown in Figures 9 and 10, a positive electrode tab 260, consisting of a positive electrode core 241, is provided at one end of the positive electrode plate 240 in the width direction. When the positive electrode plates 240 are stacked, multiple positive electrode tabs 260 are stacked to form a positive electrode tab group 250. The positive electrode tab group 250 is electrically connected to the positive electrode. The length of each positive electrode tab 260 in the protruding direction on the multiple positive electrode plates 240 is appropriately adjusted considering the state in which the positive electrode tab group 250 is connected to the positive electrode current collector 400B. The shape of the positive electrode tab 260 is not limited to that illustrated in Figure 10.

[0063] A positive electrode protective layer 243 is provided at the base of the positive electrode tab 260. However, the positive electrode protective layer 243 is not necessarily provided at the base of the positive electrode tab 260.

[0064] In a typical example, the thickness of one negative electrode tab 230 is less than the thickness of one positive electrode tab 260. In this case, the thickness of the negative electrode tab group 220 is less than the thickness of the positive electrode tab group 250.

[0065] (Connection structure between electrode body 200 and current collector 400) The connection structure between the electrode body 200 and the current collector 400 will be described with reference to Figures 11 and 12.

[0066] As shown in Figures 11 and 12, the electrode body 200 includes a first electrode body 201 and a second electrode body 202. Each of the first electrode body 201 and the second electrode body 202 includes a positive electrode and a negative electrode. The electrode body 200 may be composed of three or more electrode bodies.

[0067] The electrode body 200 is formed by stacking a first electrode body 201 and a second electrode body 202. The first electrode body 201 and the second electrode body 202 are aligned in the thickness direction (Y direction) of the first electrode body 201 and the second electrode body 202.

[0068] As shown in Figure 11 (connection structure on the negative electrode side), the first electrode body 201 includes a group of negative electrode tabs 220. The group of negative electrode tabs 220 is electrically connected to the current collector 410 (negative electrode current collector) at its first end 205 in the X direction. The second electrode body 202 includes a group of negative electrode tabs 270. The group of negative electrode tabs 270 is electrically connected to the current collector 410 (negative electrode current collector) at its third end 207 in the X direction.

[0069] The negative electrode tab group 220 has a curved portion 221 and a tip portion 222. The curved portion 221 is the part of the negative electrode tab group 220 that is curved. The tip portion 222 is the part located at the end of the negative electrode tab group 220.

[0070] The negative electrode tab group 270 has a curved portion 271 and a tip portion 272. The curved portion 271 is the part of the negative electrode tab group 270 that is curved. The tip portion 272 is the part located at the end of the negative electrode tab group 270.

[0071] Each of the negative electrode tab group 220 and negative electrode tab group 270 is curved in opposite directions such that their tips 222 and 272 are closer together. In this embodiment, the tips 222 and 272 are spaced apart, but the configuration is not limited to this, and the tips 222 and 272 may be in contact with each other.

[0072] The negative electrode current collector 400A electrically connects the negative electrode terminal 301 to the negative electrode tab group 220 and the negative electrode tab group 270. In this embodiment, the negative electrode current collector 400A is connected to the negative electrode terminal 301 between the electrode body 200 and the sealing plate 120. The negative electrode current collector 400A includes current collectors 410 and 430.

[0073] The current collector 410 is a plate-shaped member. The current collector 410 has a longitudinal direction in the Z direction and a short direction in the Y direction. The current collector 410 is made up of a single, integrated part. The current collector 430 is a plate-shaped member. The current collector 430 has a longitudinal direction in the Z direction and a short direction in the Y direction. The current collectors 410 and 430 are arranged in parallel in the X direction. Thus, the current collectors 410 and 430 are made up of separate parts.

[0074] The negative electrode tab groups 220 and 270 are joined to the current collector 410 at a joint 411, which will be described later (see Figure 15). The joint 411 can be formed, for example, by laser welding.

[0075] The current collector 430 is joined to the current collector 410 at a joint located at its Z-direction end. The current collector 430 is connected to the negative terminal 301. The connection between the current collector 430 and the negative terminal 301 can be formed, for example, by crimping and / or welding.

[0076] The negative electrode terminal 301 is exposed to the outside of the sealing plate 120. The negative electrode terminal 301 is connected to the plate-shaped member 303. The negative electrode terminal 301 includes a region 301A made of copper or a copper alloy and a region 301B made of aluminum or an aluminum alloy, and it is preferable that the region 301A made of copper or a copper alloy is connected to the current collector 430.

[0077] The plate-shaped member 303 is located on the outside of the sealing plate 120. The plate-shaped member 303 is arranged along the sealing plate 120. The plate-shaped member 303 is electrically conductive. The plate-shaped member 303 is positioned to secure connection area with busbars, etc., that electrically connect the secondary battery 1 to other adjacent secondary batteries. The connection between the negative electrode terminal 301 and the plate-shaped member 303 can be formed, for example, by laser welding.

[0078] An insulating member 510 is placed between the plate-shaped member 303 and the sealing plate 120. An insulating member 520 is placed between the negative terminal 301 and the sealing plate 120. An insulating member 530 is placed between the current collector 430 and the sealing plate 120.

[0079] However, the negative terminal 301 may be electrically connected to the sealing plate 120. The sealing plate 120 may also serve as the negative terminal 301.

[0080] A spacer 600 is positioned between the sealing plate 120 and the main body of the electrode body 200 (excluding the negative electrode tab groups 220 and 270). The spacer 600 is made of an insulating resin material. The spacer 600 suppresses the movement of the electrode body 200 within the case 100 in the X direction, thereby suppressing damage to the negative electrode tab group 220, the negative electrode tab group 270, and the electrode body 200.

[0081] As shown in Figure 12 (connection structure on the positive electrode side), the connection structure between the electrode body 200 and the current collector 400 on the positive electrode side differs from the configuration on the negative electrode side in that the part corresponding to the current collector 410 on the negative electrode side is composed of two parts.

[0082] The first electrode body 201 includes a group of positive electrode tabs 250. The group of positive electrode tabs 250 is electrically connected to the current collector 420 (positive electrode current collector) at a second end 206 in the X direction. The second electrode body 202 includes a group of positive electrode tabs 280. The group of positive electrode tabs 280 is electrically connected to the current collector 420 at a fourth end 208 in the X direction.

[0083] The positive electrode tab group 250 has a curved portion 251 and a tip portion 252. The curved portion 251 is the part of the positive electrode tab group 250 that is curved. The tip portion 252 is the part located at the end of the positive electrode tab group 250.

[0084] The positive electrode tab group 280 has a curved portion 281 and a tip portion 282. The curved portion 281 is the part of the positive electrode tab group 280 that is curved. The tip portion 282 is the part located at the end of the positive electrode tab group 280.

[0085] Each of the positive electrode tab group 250 and the positive electrode tab group 280 is curved in opposite directions such that their tips 252 and 282 are closer together. In this embodiment, the tips 252 and 272 are spaced apart, but the configuration is not limited to this, and the tips 252 and 282 may be in contact with each other.

[0086] The positive electrode current collector 400B electrically connects the positive electrode terminal 302 to the positive electrode tab group 250 and the positive electrode tab group 280. In this embodiment, the positive electrode current collector 400B is connected to the positive electrode terminal 302 between the electrode body 200 and the sealing plate 130.

[0087] The positive electrode current collector 400B includes a current collector 420 and a current collector 440. An insulating member 460 is interposed between the current collector 420 and the current collector 440, but the two are electrically joined at a position different from the cross-section shown in the figure.

[0088] The current collector 420 is a plate-shaped member. The current collector 420 has a longitudinal direction in the Z direction and a short direction in the Y direction. The current collector 420 is composed of one current collector and another current collector. That is, the current collector 420 is composed of two parts.

[0089] The positive electrode tab group 250 and the positive electrode tab group 280 are joined to the current collector 420, which is composed of two parts, at a joint 421 (see Figure 15), which will be described later. The joint 421 can be formed, for example, by laser welding.

[0090] The current collector 440 is joined to the current collector 420 at a joint located at its Z-direction end. The current collector 440 is connected to the positive terminal 302. The connection between the current collector 440 and the positive terminal 302 can be formed, for example, by crimping and / or welding.

[0091] The positive terminal 302 is exposed on the outside of the sealing plate 130 and is positioned to reach the current collector 440 of the positive current collector 400B, which is located on the inner surface side of the sealing plate 130. The positive terminal 302 is connected to the plate-shaped member 304.

[0092] The plate-shaped member 304 is located on the outside of the sealing plate 130. The plate-shaped member 304 is arranged along the sealing plate 130. The plate-shaped member 304 is conductive. The plate-shaped member 304 is arranged to secure connection area with busbars, etc., that electrically connect the secondary battery 1 to other adjacent secondary batteries. The connection between the positive electrode terminal 302 and the plate-shaped member 304 can be formed, for example, by laser welding.

[0093] An insulating member 510 is placed between the plate-shaped member 304 and the sealing plate 130. An insulating member 520 is placed between the positive terminal 302 and the sealing plate 130. An insulating member 470 is placed between the current collector 440 and the sealing plate 130.

[0094] However, the positive terminal 302 may be electrically connected to the sealing plate 130. The sealing plate 130 may also serve the role of the positive terminal 302.

[0095] A spacer 600 is positioned between the sealing plate 130 and the main body of the electrode body 200 (excluding the positive electrode tab groups 250 and 280). The spacer 600 is made of an insulating resin material. The spacer 600 suppresses the movement of the electrode body 200 within the case 100 in the X direction, thereby suppressing damage to the positive electrode tab groups 250 and 280 and the electrode body 200.

[0096] The spacer 600 shown in Figures 11 and 12 is made of, for example, resin. The material of the spacer 600 may be, for example, polypropylene (PP), polyphenylene sulfide (PPS), polybutylene terephthalate (PBT), or ethylene propylene diene rubber (EPDM).

[0097] As shown in Figures 11 and 12, a resin insulating sheet 700 (electrode holder) is placed between the electrode body 200 and the case body 110. The insulating sheet 700 may be made of resin, for example. More specifically, the material of the insulating sheet 700 may be polypropylene (PP), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyimide (PI), or polyolefin (PO).

[0098] (Manufacturing process for secondary battery 1) The method for manufacturing a secondary battery according to this embodiment will be described below using the flowchart in Figure 13. In the method for manufacturing a secondary battery according to this embodiment, first, the first electrode body 201 and the second electrode body 202 are manufactured (step S1). It is preferable that a portion of the tip of each of the negative electrode tab group 220, positive electrode tab group 250, negative electrode tab group 270, and positive electrode tab group 280 is cut so that when the tips are bundled together they are the same length.

[0099] As shown in Figures 14 and 15, after the first electrode body 201 and the second electrode body 202 are fabricated, the positive electrode tab groups 250 and 280 are joined to the current collector 420 (step S2). The positive electrode tab groups 250 and 280 are joined to the current collector 420 at the joining point 421.

[0100] Next, the first electrode body 201, the current collector 410, and the second electrode body 202 are arranged in this order in the DR1 direction. The negative electrode tab group 220 is placed on one side of the current collector 410 in the DR1 direction. With the negative electrode tab group 270 placed on the other side of the current collector 410 in the DR1 direction, the negative electrode tab group 220 and the negative electrode tab group 270 are joined to the current collector 410 (step S3). The negative electrode tab group 220 and the negative electrode tab group 270 are joined to the current collector 410 at the joining point 411.

[0101] In the height direction of the first electrode body 201 and the second electrode body 202, the current collectors 410 and 420 are positioned off-center to one side of the center of the first electrode body 201 and the second electrode body 202. This allows the current collectors to be made shorter, thus enabling them to be made smaller. The current collectors 410 and 420 are not limited to this configuration. The current collectors 410 and 420 may be positioned in the center of the first electrode body 201 and the second electrode body 202 in the height direction of the first electrode body 201 and the second electrode body 202.

[0102] The order in which the current collectors 410 and 420 are joined to the first electrode body 201 and the second electrode body 202 is not limited to the above, and the order may be changed. The step of joining the current collectors 420 to the first electrode body 201 and the second electrode body 202 is preferably performed before the step of overlapping the first electrode body 201 and the second electrode body 202, which will be described later, and is preferably performed before the step of joining the current collector 410 to the first electrode body 201 and the second electrode body 202.

[0103] Next, after joining the negative electrode tab group 220 and the negative electrode tab group 270 to the current collector 410, the negative electrode tab group 220 and the negative electrode tab group 270 are bent in the thickness direction of the first electrode body 201 and the second electrode body 202 (in the direction perpendicular to the DR1 direction in Figures 17 and 18) to overlap the first electrode body 201 and the second electrode body 202 (step S4). In other words, the first electrode body 201 and the second electrode body 202 are brought together.

[0104] "Overlapping the first electrode and the second electrode" means that the first electrode and the second electrode may be directly overlapped, or other components may be placed between the first electrode and the second electrode. The first electrode and the second electrode may or may not be fixed with tape or the like. Furthermore, the first electrode, the current collector and the second electrode do not have to be arranged in a straight line in the DR1 direction, and the first electrode or the second electrode may be inclined with respect to the current collector in the DR1 direction.

[0105] The negative electrode tab group 220 and the negative electrode tab group 270 are bent so that their tips face each other. The positive electrode tab group 250 and the positive electrode tab group 280 are also bent so that their tips face each other.

[0106] Next, as shown in Figure 16, the spacers 600 and insulating sheet 700 are assembled to the electrode body 200 (step S5). After assembling the spacers 600 to both the negative and positive electrode sides of the electrode body 200, the electrode body 200 and the spacers 600 on both sides are covered with the insulating sheet 700. In this way, with the spacers 600 positioned on both sides of the electrode body 200, the electrode body 200 and the spacers 600 on both sides are covered with the insulating sheet 700. The insulating sheet 700 is fixed to the spacers 600 on both sides.

[0107] Next, as shown in Figures 17 and 18, the current collector 410 is electrically connected to the negative terminal 301 via the current collector 430 (step S6). Step S6 can also be performed before step S5. Specifically, as shown in Figure 18, the negative tab group 220 and the negative tab group 270 are bent so that their tips 222 and 272 face each other.

[0108] The negative electrode terminal 301 and the current collector 430 are attached to the sealing plate 120 via an insulating member. The current collector 430 is brought into contact with the current collector 410 in the X direction. The connection of the plate-shaped member 303 to the negative electrode terminal 301 can be done at any time. The current collector 430 and the current collector 410 are joined by laser welding from between the sealing plate 120 and the insulating sheet 700.

[0109] Next, the spacer 600 and electrode body 200 are inserted into the case body 110 through the opening 113, with the current collector 420 side leading (step S7). Then, from the state in which the negative electrode tab group 220 and negative electrode tab group 270 are extended, the negative electrode tab group 220 and negative electrode tab group 270 are bent by bringing the sealing plate 120 and the main body of the electrode body 200 (first electrode body 201 and second electrode body 202) closer together (state shown in Figure 11). The negative electrode tab group 220 and negative electrode tab group 270 are bent along the shape of the spacer 600 so that the folded portions of the bent parts 221 and 271 are closer to the case body 110 in the Y direction.

[0110] As shown in Figure 19, after the sealing plate 120 is brought into contact with the case body 110, the sealing plate 120 is temporarily joined to the case body 110. This temporary joining partially joins the sealing plate 120 to the opening 113 of the case body 110. This positions the sealing plate 120 relative to the case body 110.

[0111] When inserting the electrode body 200 into the case body 110, the electrode body 200 may be pulled from the current collector 420 side or pushed from the current collector 410 side. When the electrode body 200 is pushed from the current collector 410 side, the negative electrode tab group 220 and the negative electrode tab group 270 can be bent at the same time.

[0112] After inserting the electrode body 200 into the case body 110, the current collector 420 is electrically connected to the positive terminal 302 (step S8). Specifically, the positive terminal 302 is attached to the sealing plate 130 via an insulating member. After inserting the first electrode body 201 and the second electrode body 202 into the case body 110, the current collector 440 is brought into contact with the current collector 420 protruding from the opening 114 in the X direction. The connection of the plate-shaped member 304 to the positive terminal 302 can be done at any time.

[0113] The positive electrode tab groups 250 and 280 connected to the current collector 420 are bent so that their tips 252 and 282 face each other. As shown in Figure 12, the positive electrode tab groups 250 and 280 are curved to conform to the shape of the spacer 600 so that the folded portions of the curved sections 251 and 281 approach the case body 110 in the Y direction.

[0114] After inserting the spacer 600 and electrode body 200 into the case body 110, the sealing plate 130 and sealing plate 120 are joined to the case body 110 (step S9).

[0115] As shown in Figure 20, after the sealing plate 130 is brought into contact with the case body 110, the sealing plate 130 is tack-welded to the case body 110. Through this tack-welding, the sealing plate 130 is partially joined to the opening 114 of the case body 110. This positions the sealing plate 130 relative to the case body 110.

[0116] Next, the sealing plates 120 and 130 are joined to the case body 110. Sealing plate 120 seals the opening 113 of the case body 110, and sealing plate 130 seals the opening 114 of the case body 110. As a result, the first electrode body 201 and the second electrode body 202 are housed in the case 100.

[0117] After the above process, inspections such as leak testing are performed (S10 process). After the leak testing, the secondary battery 1 is dried to remove moisture from inside the case 100.

[0118] Next, with the sealing plate 130 positioned above the sealing plate 120 in the vertical direction and the spacer 600 positioned below the electrode body 200, the electrolyte is injected into the case 100 through the injection hole 134 provided in the sealing plate 130 (step S11). Because the spacer 600 is provided around where the electrolyte is injected, damage to the electrode body 200 and other components is suppressed even if the electrolyte is injected forcefully into the case 100. As a result, the secondary battery 1 of this embodiment can inject the electrolyte in a shorter time compared to the case without the spacer 600. After that, degassing and charging are performed. During degassing and charging, the injection hole 134 may be temporarily sealed. After that, the injection hole 134 is sealed, and the secondary battery 1 is completed.

[0119] (Connecting electrode tabs) Next, the joining of electrode tabs in the electrode tab group will be described. As shown in Figure 21, the negative electrode tabs 230 (first electrode tabs) are joined together using the horn 10 and the anvil 20 to form a negative electrode tab group 220 (first electrode tab group). At this time, the horn 10 vibrates in the direction of arrow A while pressing the negative electrode tabs 230 in the direction of arrow B. Although Figure 21 shows an example with four stacked tabs, it is preferable to have five or more stacked tabs, more preferably ten or more, and even more preferably twenty or more.

[0120] As shown in Figure 22, when forming a joint in the negative electrode tab group 220, it is preferable that the horn 10 be located on the tip side of the negative electrode tab group 220. This makes it possible to more effectively suppress excessive load on the base N of the negative electrode tab (particularly the base of the negative electrode tab 230 located near the outermost edge in the stacking direction) when the horn 10 is vibrated, thereby preventing damage to the base of the negative electrode tab 230. For example, in the longest negative electrode tab 230 in the negative electrode tab group 220, it is preferable that the entire horn 10 be in contact with a region within 1 / 3 of the length of the negative electrode tab 230 from the tip of the negative electrode tab 230.

[0121] As shown in Figures 23 and 24, the horn 10 includes a linear projection 11 (first projection), a base surface 12, a convex portion 13, and a main body 14. Multiple linear projections 11 are formed so as to extend substantially parallel to each other (in substantially the same direction). The linear projections 11 are preferably formed in a straight line, but may also be curved. In a plan view of the linear projection 11 (when viewed from a direction perpendicular to the base surface), the ratio (L / B) of the length of the projection 11 (length along the curve in the case of a curved shape) L to the width of the projection 11 is preferably 3 or more, more preferably 5 or more, and even more preferably 10 or more.

[0122] Furthermore, in a configuration where multiple linear projections 11 extend in substantially the same direction, the inclination of one linear projection 11 relative to the other linear projections 11 is preferably within ±15 degrees, more preferably within ±10 degrees, and even more preferably within ±5 degrees.

[0123] The projection 11 is provided so as to protrude from the base surface 12. The top of the projection 11 extends linearly. In the examples of Figures 23 and 24, multiple (3) projections 11 are provided, but the number of projections 11 can be changed as appropriate. There may be only one projection 11. The base surface 12 constitutes the upper surface of the convex portion 13. In the examples of Figures 23 and 24, the base surface 12 is a flat surface. The convex portion 13 is provided so as to protrude from the main body 14. The convex portion 13 has curved sides, and its length and width gradually decrease as it moves away from the main body 14. However, the shape of the convex portion 13 is not limited to this.

[0124] In the process of forming the joint between the negative electrode tabs 230, vibration (e.g., ultrasonic vibration) is applied while the projection 11 is in contact with the group of negative electrode tabs 220. At this time, the horn 10 vibrates in a direction that is approximately perpendicular (intersecting) to the direction in which the linear projection 11 extends. The linear projection 11 does not necessarily have to be approximately perpendicular to the direction of vibration. It is preferable that the projection 11 intersects the direction of vibration at an angle of about 90° ± 30° or less, and more preferably at an angle of about 90° ± 15° or less.

[0125] As shown in Figure 25, the linear projection 11 on the horn 10 is positioned near the center of the joint 411. As shown in Figure 26, the anvil 20 has a flat region 21 (first region) facing the projection 11 and a projection-forming region 22 (second region) provided around the flat region 21. Multiple projections (second projections) are formed in the projection-forming region 22. The projections of the anvil 20 formed in the projection-forming region 22 do not have to be linear projections, and may be, for example, a square pyramidal shape with an aspect ratio (long axis length / short axis length) of less than 2 in plan view (when viewed from a direction perpendicular to the contact surface with the negative electrode tab group 220), or a conical shape, hemispherical shape, etc. It is preferable that one projection (second projection) formed in the projection-forming region 22 of the anvil 20 has a smaller area (the area surrounded by the contour of the base of each projection when viewed along the projection direction) than one projection 11 (first projection) in plan view (Figure 26). For example, it is preferable that (area of ​​one second projection) / (area of ​​one first projection) be approximately 0.5 or less, more preferably approximately 0.3 or less, and even more preferably approximately 0.1 or less.

[0126] The flat region 21 of the anvil 20 may have fine irregularities, similar to those present on the surface of parts of the anvil 20 where no protrusions are formed. In the flat region 21, it is preferable that there are no protrusions with a height of approximately 0.03 mm or more, and it is more preferable that there are no protrusions with a height of approximately 0.01 mm or more.

[0127] The flat region 21 of the anvil 20 is preferably a region that includes at least a 3mm x 5mm rectangular area and is free of protrusions (excluding the fine irregularities mentioned above). More preferably, it is preferable to form a region that includes at least a 3mm x 8mm rectangular area and is free of protrusions.

[0128] The height of the protrusion (second protrusion) formed in the protrusion-forming region 22 of the anvil 20 is preferably about 0.05 mm or more, more preferably about 0.08 mm or more, and even more preferably about 0.1 mm or more.

[0129] As shown in Figure 27, a recess 2201A is formed at the junction 411 between the negative electrode tab group 220 and the current collector 410. The recess 2201A is formed to extend in a direction (Z direction) perpendicular to the direction (X direction) in which the negative electrode tab group 220 protrudes from the main body of the electrode body 200. The recess 2201A is formed to extend in the height direction (Z direction) of the electrode body 200.

[0130] As shown in Figures 28 to 30, one outer surface (first outer surface) of the negative electrode tab group 220 has a recess 2201A (first recess) as an indentation mark of the projection 11 and a recess 2202A (second recess) as an indentation mark of the convex portion 13.

[0131] The recess 2201A is formed at the bottom of the recess 2202A. In the region 2201B (first bonding region) where the recess 2201A is formed, the negative electrode tabs 230 are bonded to each other with a relatively strong bonding strength. In the region 2202B (second bonding region) formed around region 2201B, the negative electrode tabs 230 are bonded to each other with a relatively weaker bonding strength compared to region 2201B. In addition, there may be areas in region 2201B where the negative electrode tabs 230 are not bonded to each other.

[0132] In the examples shown in Figures 29 and 30, the side walls of the recess 2202A are inclined in a direction that widens the recess 2202A toward the opening. The inclination of the side wall 2201C (first side wall) extending in the same direction as the linear recess 2201A (see Figure 29) is gentler (the angle of intersection with the bottom surface of the recess 2202A is smaller) than the inclination of the side walls 2202C (second side walls) located at both ends of the linear recess 2201A (see Figure 30). However, the inclination of the side walls of the recess 2202A is not limited to the examples described above.

[0133] After the negative electrode tabs 230 are joined together, the group of negative electrode tabs 220 is joined to the current collector 410 (first conductive member). At this time, the current collector 410 is brought into contact with the outer surface (second outer surface) of the group of negative electrode tabs 220 located on the opposite side (the far side of the page in Figure 28) from the surface where the recess 2201A (region 2201B), which is the imprint of the projection 11, is formed. This allows the current collector 410 to be superimposed on the portion where the flat region 21 of the anvil 20 was in contact. In this state, the group of negative electrode tabs 220 and the current collector 410 are joined by irradiating them with laser light (energy rays) from the recess 2201A side (the near side of the page in Figure 28).

[0134] Macroscopically, the laser beam is scanned in a direction approximately perpendicular (intersecting) to the extending direction of the recess 2201A (region 2201B). Therefore, the laser welded joint 411A that joins the negative electrode tab group 220 and the current collector 410 extends in a direction approximately perpendicular (intersecting) to the extending direction of the recess 2201A (region 2201B). When using laser light as the energy beam, it may be a continuous oscillation type or a pulsed type.

[0135] By making the extending direction of the laser-welded portion 411A intersect with the extending direction of the recess 2201A (region 2201B), an overlapping region between the laser-welded portion 411A and region 2201B of the negative electrode tab group 220 can be reliably formed. This allows for a more reliable connection between the region 2201B, where the negative electrode tabs 230 of the negative electrode tab group 220 are relatively firmly joined, and the current collector 410, thereby increasing the reliability of the joint between the negative electrode tab group 220 and the current collector 410. Furthermore, it is possible to suppress the occurrence of necking during laser welding and improve the reliability of the electrical connection between the negative electrode tab group 220 and the current collector 410.

[0136] The laser beam for joining the negative electrode tab group 220 and the current collector 410 may be irradiated only to the bottom of the recess 2202A, or it may be irradiated to the bottom and side walls of the recess 2202A, or it may extend beyond the bottom and side walls of the recess 2202A to the outside of the recess 2202A. When the laser beam is also irradiated to the side walls of the recess 2202A, it is preferable that the inclination of the side wall 2201C (first side wall), which is the first part of the side wall irradiated with the laser beam (see Figure 29), is gentler than the inclination of the side wall 2202C (second side wall), which is the second part of the side wall irradiated with the laser beam (see Figure 30).

[0137] According to the bonding process of this embodiment, the linear projection 11 formed on the horn 10 allows vibration to be applied while stably holding the negative electrode tab group 220, thereby improving the reliability of the bonding between the negative electrode tabs 230. Furthermore, damage to the negative electrode tabs 230 can be effectively suppressed. As a result, a highly reliable secondary battery 1 can be obtained. However, in this technology, the projection 11 (first projection) of the horn 10 does not necessarily have to be linear.

[0138] Furthermore, according to the joining process of this embodiment, by providing a flat region 21 on the anvil 20 that faces the projection 11 of the horn 10 with the negative electrode tab group 220 in between, the current collector 410 can be superimposed on the portion that the flat region 21 was in contact with. Therefore, laser welding can be performed in portions where the gap between the negative electrode tab group 220 and the current collector 410 is small, and the occurrence of blowholes during welding can be effectively suppressed. As a result, the reliability of the joint between the negative electrode tab group 220 and the current collector 410 can be improved. As a result, a highly reliable secondary battery 1 can be obtained.

[0139] As shown in Figure 31, a flat region 2203 (first region) is formed on the lower surface (second outer surface) of the region opposite to the recess 2201A (first recess) formed on the upper surface (first outer surface). Region 2203 corresponds to the region in contact with the flat region 21 of the anvil 20. By placing the current collector 410 on region 2203 and irradiating it with a laser from the recess 2201A side, laser welding can be performed in the portion where the gap between the negative electrode tab group 220 and the current collector 410 is small. Around region 2203, a recess 2204A is formed, which is an indentation mark caused by the protrusion of the anvil 20.

[0140] As illustrated in Figure 31, it is preferable that the depth of recess 2201A (indentation caused by the horn projection) is greater than the depth of recess 2204A (indentation caused by the anvil projection). It is also preferable that the opening width of recess 2201A (indentation caused by the horn projection) is wider than the opening width of recess 2204A (indentation caused by the anvil projection). Furthermore, it is preferable that the number of recesses 2201A (indentation caused by the horn projection) is less than the number of recesses 2204A (indentation caused by the anvil projection). This results in each recess 2201A being relatively large, ensuring that energy rays can be reliably irradiated into the recess 2201A.

[0141] In the example described above (Figure 26), an example was shown in which the projection-forming region 22 of the anvil 20 surrounds the flat region 21 and is formed in an annular shape. By doing so, it is possible to effectively suppress foil displacement between the negative electrode tabs 230 during ultrasonic vibration of the horn 10 and to form a stable joint between the negative electrode tabs 230.

[0142] When the projection-forming region 22 is formed in an annular shape surrounding the flat region 21, the flat region 21 surrounded by the projection-forming region 22 has a length of 40 mm in a planar view (Figure 26). 2 Approximately (more preferably 50 mm) 2 Approximately the above, and more preferably 80 mm. 2It is preferable that the projection-forming region 22 has an area (S21) of approximately the above. In this case, the area (S22) of the projection-forming region 22 in plan view can be approximately the same as or less than the area (S21) of the flat region 21. For example, the area (S22) of the projection-forming region 22 in plan view may be 50 mm 2 Approximately the following, or 40mm 2 The area can be approximately as follows. Note that the area of ​​the projection-forming region 22 in plan view (S22) referred to here is the area on the flat surface including the flat region 21, and corresponds to the area of ​​the smallest region that encompasses a group of regularly arranged projections.

[0143] When the projection-forming region 22 is formed in an annular shape surrounding the flat region 21, the projections of the anvil 20 in the projection-forming region 22 are 160 per 10 mm. 2 Density of the above (10mm 2 It is preferable that the area is provided with 160 or more protrusions.

[0144] In a plan view (Figure 26), it is preferable that a portion of the area (S11) of the projection 11 of the horn 10, with an area of ​​approximately 0.5 × S11 or more (more preferably approximately 0.7 × S11 or more, and even more preferably approximately 0.9 × S11 or more), faces the flat region 21 of the anvil 20. In a plan view (Figure 26), it is even more preferable that the entire area (area: S11) of the projection 11 of the horn 10 faces the flat region 21 of the anvil 20.

[0145] The arrangement of the projection 11 of the horn 10, and the flat region 21 and projection-forming region 22 of the anvil 20, is not limited to those illustrated in Figure 26. The flat region 21 does not necessarily have to be surrounded by the projection-forming region 22. Also, the projection 11 of the horn 10 and a part of the projection-forming region 22 may overlap in a plan view (Figure 26).

[0146] As shown in Figure 32, in the anvil 20, a projection (third projection) is formed instead of the flat region 21 as the first region, but the height of this projection may be lower than the height of the projection (second projection) provided in the projection-forming region 22 (second region). This region, like the flat region 21, corresponds to the first region of the anvil 20. In the example in Figure 32, a recess 2203A (third recess), which is the indentation mark of the projection of the anvil 20, is formed in the portion of the outer surface (second outer surface) of the negative electrode tab group 220 that abuts the first region of the anvil 20. The recess 2203A formed in region 2203 can be formed shallower than the recess 2204A formed around region 2203. Therefore, it is possible to suppress the occurrence of a large gap between the outer surface of the negative electrode tab group 220 and the current collector 410, and the negative electrode tab group 220 and the current collector 410 can be stably joined.

[0147] For example, it is preferable that the height of the projection (third projection) formed in the first region of the anvil 20 be about half or less of the height of the projection (second projection) provided in the projection-forming region 22, more preferably about one-third or less, and even more preferably about one-fifth or less.

[0148] As shown in Figure 33, in the anvil 20, a (third projection) is formed in place of the flat region 21 as the first region, but a region may be provided in which the formation density of the projection (the ratio of the area occupied by the projection per unit area) is lower than the formation density of the projection in the projection formation region 22 (second region). This region, like the flat region 21, corresponds to the first region of the anvil 20. In the example in Figure 33, a recess 2203A (third recess), which is the indentation mark of the projection of the anvil 20, is formed in the portion of the outer surface (second outer surface) of the negative electrode tab group 220 that is in contact with the first region of the anvil 20. The number of recesses 2203A formed in region 2203 can be fewer, or the opening area can be smaller, than the recesses 2204A formed around region 2203. Therefore, it is possible to suppress the occurrence of a large gap between the outer surface of the negative electrode tab group 220 and the current collector 410, and the negative electrode tab group 220 and the current collector 410 can be stably joined.

[0149] In addition, for example, in the anvil 20, it is preferable that the value of (total area of the third protrusions formed in the first region in plan view / area of the first region in plan view) / (total area of the second protrusions formed in the second region in plan view / area of the second region in plan view) is about 1 / 2 or less, more preferably about 1 / 3 or less, and even more preferably about 1 / 5 or less.

[0150] (Modified example) For example, in the modified example of FIG. 34, two protrusion forming regions 22 extending substantially parallel to the linear protrusion 11 are provided on both sides of the flat region 21. In the modified example of FIG. 34, compared with the above example (FIG. 26), since the range of the protrusion forming region 22 is limited, foil breakage of the negative electrode tab 230 can be effectively suppressed. At this time, since the protrusion forming region 22 extends in a direction substantially orthogonal to the vibration direction of the horn 10 and the protrusion forming regions 22 are formed on both sides of the linear protrusion 11 in the vibration direction of the horn 10, foil displacement between the negative electrode tabs 230 during ultrasonic vibration of the horn 10 can be effectively suppressed.

[0151] It is preferable to form a plurality of linear protrusion forming regions 22. When forming a plurality of linear protrusion forming regions 22, it is preferable to form them substantially parallel to each other.

[0152] In the example of FIG. 34, the protrusion forming region 22 preferably has an area (S22) of about 60 mm 2 or less. Further, in the protrusion forming region 22, the protrusions of the anvil 20 can be provided at a density of about 110 or less per 10 mm 2 (110 or more protrusions are provided in a 10 mm 2 region).

[0153] Also, in the modified example of FIG. 35, four protrusion forming regions 22 are provided separately at the four corners of the flat region 21. In the modified example of FIG. 35, compared with the example of FIG. 34, since the range of the protrusion forming region 22 is further limited, foil breakage of the negative electrode tab 230 can be suppressed to the maximum extent.

[0154] In the modified examples shown in Figures 34 and 35, the anvil 20 has a flat region 21 (first region) facing the projection 11 and a projection-forming region 22 (second region) provided around the flat region 21. As in the example described above, laser welding can be performed with the current collector 410 superimposed on the region 2203 of the negative electrode tab group 220.

[0155] In the example described above, for the sake of explanation, the joining of the negative electrode tab group 220 and the current collector 410 was explained. However, when using an electrode body 200 formed by stacking the first electrode body 201 and the second electrode body 202, the negative electrode tab groups 220 and 270 are stacked on the current collector 410, and then the negative electrode tab groups 220 and 270 are joined to the current collector 410. The joining of the positive electrode tab groups 250 and 280 is the same as that of the negative electrode tab groups 220 and 270.

[0156] In the above example, the negative electrode tab group 220 is joined to the current collector 410, and then the current collector 410 is joined to the current collector 430 attached to the sealing plate 120. However, the negative electrode tab group 220 may be directly joined to the current collector 430 attached to the sealing plate 120 (the current collector 410 may be omitted). This eliminates the need for the current collector 410, thereby reducing internal resistance or increasing energy density. In this case, it is preferable to join the negative electrode tab group 220 and the negative electrode tab group 270 to the current collector 430 attached to the sealing plate 120, and then bend the negative electrode tab group 220 and the negative electrode tab group 270, respectively, to overlap the first electrode body 201 and the second electrode body 202. This further increases energy density.

[0157] The negative electrode tab 230 and the positive electrode tab 260 are preferably metal foils. The negative electrode tab 230 is preferably made of copper foil or copper alloy foil. The positive electrode tab 260 is preferably made of aluminum foil or aluminum alloy foil.

[0158] The thickness of each negative electrode tab 230 and positive electrode tab 260 is preferably about 3 μm or more, and more preferably about 5 μm or more. The thickness of each negative electrode tab 230 and positive electrode tab 260 is preferably about 50 μm or less, more preferably about 30 μm or less, and even more preferably about 20 μm or less.

[0159] It is preferable that the electrode tabs and current collectors that are joined to each other be made of the same material. If the negative electrode tab 230 is made of copper or a copper alloy, it is preferable that the current collector 410 joined to the negative electrode tab 230 is also made of copper or a copper alloy. If the positive electrode tab 260 is made of aluminum or an aluminum alloy, it is preferable that the current collector 420 joined to the positive electrode tab is also made of aluminum or an aluminum alloy.

[0160] In the above-described embodiment, an example was shown in which a first region (flat region 21, etc.) and a second region (projection-forming region 22) are provided on the anvil 20. However, the scope of this technology is not limited to this, and it is also possible to provide a first region and a second region on the horn 10 and a first projection on the anvil 20.

[0161] While embodiments of the present technology have been described above, the embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present technology is defined by the claims, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of Symbols]

[0162] 1 Secondary battery, 10 Horn, 11 Projection, 12 Base surface, 13 Convex part, 14 Main body, 20 Anvil, 21 Flat area, 22 Projection forming area, 100 Case, 110 Case body, 111 First side part, 112, 112A, 112B Second side part, 113, 114 Opening, 115 Joint part, 120, 130 Sealing plate, 134 Liquid injection hole, 150 Gas discharge valve, 200 Electrode body, 201 First electrode body, 202 Second electrode body, 205 First end, 206 Second end, 207 Third end, 208 Fourth end, 210 Negative electrode plate, 211 Negative electrode core body, 220 Negative electrode tab group, 221 Curved part, 222 Tip part, 230 Negative electrode tab, 240 Positive electrode plate, 241 Positive electrode core, 243 Positive electrode protective layer, 250 Positive electrode tab group, 251 Curved section, 252 Tip section, 260 Positive electrode tab, 270 Negative electrode tab group, 271 Curved section, 272 Tip section, 280 Positive electrode tab group, 281 Curved section, 282 Tip section, 300 Electrode terminal, 301 Negative electrode terminal, 301A, 301B Area, 302 Positive electrode terminal, 303 Plate-shaped member, 304 Plate-shaped member, 400 Current collector, 400A Negative electrode current collector, 400B Positive electrode current collector, 410 Current collector, 411 Joint area, 411A Laser welded area, 420 Current collector, 421 Joint area, 430, 440 Current collector, 460, 470, 510, 520, 530; insulating material, 600; spacer, 700; insulating sheet, 800; joint, 2201A, 2202A, 2203A, 2204A; recess, 2201B, 2202B; area, 2203.

Claims

1. A method for manufacturing an energy storage device comprising an electrode body including a first electrode and a second electrode, wherein the electrode body has a group of first electrode tabs, each consisting of multiple stacked first electrode tabs connected to the first electrode, and the group of first electrode tabs includes a first outer surface and a second outer surface located on opposite sides of each other, A step of manufacturing an electrode body having the first group of electrode tabs, The process includes a step of forming a joint in the first electrode tab group where the first electrode tabs are joined together by applying vibration to the first electrode tab group with the horn while the first electrode tab group is sandwiched between the horn and an anvil in the stacking direction of the first electrode tabs, One of the horn and the anvil has a first projection on the surface that contacts the first outer surface of the first electrode tab group, The other of the horn and the anvil has a first region and a second region on the surface that contacts the second outer surface of the first electrode tab group, the second region is formed around the first region, and a plurality of second protrusions are formed in the second region. The first region is formed flat, A third projection is formed in the first region, and the height of the third projection is lower than the height of the second projection, or A third projection is formed in the first region, and (the total area of ​​the third projection in a plan view / the area of ​​the first region in a plan view) is smaller than (the total area of ​​the second projection in a plan view / the area of ​​the second region in a plan view), A method for manufacturing an energy storage device, comprising the step of forming the joint, wherein the first projection and the first region face each other across the first electrode tab group, the first projection abuts against the first outer surface of the first electrode tab group, and the vibration is applied while the first region and the plurality of second projections abut against the second outer surface of the first electrode tab group.

2. The method for manufacturing an energy storage device according to claim 1, wherein the first region is a flat region.

3. The method for manufacturing an energy storage device according to claim 1 or claim 2, wherein the second region is formed to surround the first region.

4. The method for manufacturing an energy storage device according to claim 3, wherein the second region is formed in an annular shape.

5. The method for manufacturing an energy storage device according to claim 1 or claim 2, wherein the first projection is formed in a linear shape.

6. The method for manufacturing an energy storage device according to claim 1 or claim 2, wherein the first projection includes a plurality of linearly formed projections extending in substantially the same direction from one another.

7. The method for manufacturing an energy storage device according to claim 1 or claim 2, wherein the joint portion includes a first joint region formed in the region in which the first projection abuts, and a second joint region formed around the first joint region.

8. A method for manufacturing an energy storage device according to claim 1 or claim 2, further comprising the step of joining the joint portion in the first electrode tab group to the first conductive member after the step of forming the joint portion.

9. A method for manufacturing an energy storage device according to claim 8, wherein the first conductive member is brought into contact with the second outer surface of the first electrode tab group, and an energy ray is irradiated onto the joint from the first outer surface side to join the joint in the first electrode tab group and the first conductive member.

10. An electrode body including a first electrode and a second electrode, The electrode body comprises a first conductive member electrically connected to the electrode body, The electrode body includes a group of first electrode tabs, each consisting of multiple first electrode tabs stacked and connected to the first electrode. The first electrode tab group includes a first outer surface and a second outer surface located on opposite sides of each other. A plurality of first recesses are formed on the first outer surface. The second outer surface has a first region and a second region, the second region is formed around the first region, and a plurality of second recesses are formed in the second region. The first region is formed flat, A third recess is formed in the first region, and the depth of the third recess is formed to be shallower than the depth of the second recess, or A third recess is formed in the first region, and (the total area of ​​the third recess in plan view / the area of ​​the first region in plan view) is smaller than (the total area of ​​the second recess in plan view / the area of ​​the second region in plan view), An energy storage device in which, when the first electrode tab group is viewed from the stacking direction of the first electrode tabs, the first recess is positioned to overlap with the first region.

11. The energy storage device according to claim 10, wherein the first region is a flat region.

12. The energy storage device according to claim 10 or claim 11, wherein the first conductive member is joined to the first region of the second outer surface.

13. The energy storage device according to claim 10 or claim 11, wherein the second region is formed to surround the first region.

14. The energy storage device according to claim 13, wherein the second region is formed in an annular shape.

15. The energy storage device according to claim 10 or claim 11, wherein the first recess is formed in a linear shape.

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