Power storage device and method for manufacturing the same

Abstract

The present application relates to a power storage device and a manufacturing method thereof, in a process of forming a joint portion, vibration is applied in a state where a first protrusion (11) and a first region (21) face each other with a first electrode tab group (220) interposed therebetween, the first protrusion (11) abuts against a first outer surface of the first electrode tab group (220), the first region (21) abuts against a second outer surface of the first electrode tab group (220), and a plurality of second protrusions abut against the second outer surface of the first electrode tab group (220).

Description

Technical Field

[0001] This technology relates to energy storage devices and their manufacturing methods. Background Technology

[0002] Japanese Patent Application Publication No. 2019-126822 discloses a method for preventing the workpiece from contacting the joint between the main body of the welding head and the plurality of protrusions during a process in which ultrasonic vibration is applied while pressing the welding head into a workpiece placed on an anvil.

[0003] In energy storage devices, conductive connections are formed. There is a need to improve the reliability of these conductive connections. From this perspective, the battery described in Japanese Patent Application Publication No. 2019-126822 still has room for improvement. Summary of the Invention

[0004] The purpose of this technology is to provide a highly reliable energy storage device and its manufacturing method.

[0005] This technology provides the following energy storage devices and methods for manufacturing them.

[0006] [1] A method for manufacturing an energy storage device, the energy storage device comprising an electrode body including a first electrode and a second electrode, the electrode body having a first electrode tab assembly formed by stacking multiple first electrode tabs connected to the first electrode, the first electrode tab assembly including a first outer surface and a second outer surface located on opposite sides, wherein the method for manufacturing the energy storage device comprises: a step of manufacturing an electrode body having the first electrode tab assembly; and a step of forming a joint whereby the first electrode tabs in the first electrode tab assembly are joined together by applying vibration to the first electrode tab assembly using the welding head in the stacking direction of the first electrode tabs in a state in which the first electrode tab assembly is clamped by a welding head and an anvil, wherein one of the welding head and the anvil has a first protrusion on the surface abutting against the first outer surface of the first electrode tab assembly, and the other of the welding head and the anvil has a first protrusion on the surface abutting against the first outer surface of the first electrode tab assembly. The surface abutting the second outer surface of the aforementioned has a first region and a second region. 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 the ratio of the total area of ​​the third protrusion in top view to the area of ​​the first region in top view is smaller than the ratio of the total area of ​​the second protrusion in top view to the area of ​​the second region in top view. In the process of forming the aforementioned joint, the aforementioned vibration is applied in a state where the first protrusion and the first region are opposite each other across the first electrode tab group, the first protrusion abuts the first outer surface of the first electrode tab group, and the first region and the plurality of second protrusions abut the second outer surface of the first electrode tab group.

[0007] [2] According to the manufacturing method of the energy storage device described in [1], the first region is a flat region.

[0008] [3] The method of manufacturing an energy storage device according to [1] or [2], wherein the second region is formed in such a way as to surround the first region.

[0009] [4] In the method of manufacturing the energy storage device according to [3], the second region is formed in a ring shape.

[0010] [5] The method of manufacturing an energy storage device according to any one of [1] to [4], wherein the first protrusion is formed in a linear shape.

[0011] [6] The method of manufacturing an energy storage device according to any one of [1] to [5], wherein the first protrusion comprises a plurality of protrusions formed in a linear shape that extend in substantially the same direction to each other.

[0012] [7] The method of manufacturing an energy storage device according to any one of [1] to [6], wherein the joint includes a first joint region formed in the area abutted by the first protrusion and a second joint region formed around the first joint region.

[0013] [8] The method for manufacturing an energy storage device according to any one of [1] to [7] further includes a step of joining the first electrode tab group to the first conductive member after the step of forming the joint.

[0014] [9] According to the method of manufacturing the energy storage device described in [8], the junction of the first electrode tab group and the first conductive member are joined by irradiating an energy line from the first outer surface side to the junction while the first conductive member is in contact with the second outer surface of the first electrode tab group.

[0015]

[10] An energy storage device comprising: an electrode body including a first electrode and a second electrode; and a first conductive member electrically connected to the electrode body, wherein the electrode body includes a first electrode tab assembly consisting of a plurality of first electrode tabs connected to the first electrode stacked together, the first electrode tab assembly including a first outer surface and a second outer surface located on opposite sides thereof, a plurality of first recesses being formed on the first outer surface, the second outer surface having a first region and a second region, the second region being formed around the first region, and a plurality of second recesses being 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 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 top view / the area of ​​the first region in top view is smaller than the total area of ​​the second recess in top view / the area of ​​the second region in top view. When the first electrode tab assembly is viewed from the stacking direction of the first electrode tab, the first recess is positioned to overlap with the first region.

[0016]

[11] According to the energy storage device described in

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

[0017]

[12] The energy storage device according to

[10] or

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

[0018]

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

[10] to

[12] , wherein the second region is formed in such a way as to surround the first region.

[0019]

[14] According to the energy storage device described in

[13] , the second region is formed in a ring shape.

[0020]

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

[10] to

[14] , wherein the first recess is formed in a linear shape.

[0021] The above and other objects, features, aspects and advantages of the invention will become clear from the following detailed description of the invention as understood in conjunction with the accompanying drawings. Attached Figure Description

[0022] Figure 1 This is a front view showing the configuration of the secondary battery involved in the embodiment.

[0023] Figure 2 This indicates viewing from the direction of arrow II. Figure 1 The diagram shows the state of the secondary battery.

[0024] Figure 3 This indicates viewing from the direction of arrow III. Figure 1 The diagram shows the state of the secondary battery.

[0025] Figure 4 This indicates viewing from the direction of arrow IV. Figure 1 The diagram shows the state of the secondary battery.

[0026] Figure 5 This indicates viewing from the direction of arrow V. Figure 1 The diagram shows the state of the secondary battery.

[0027] Figure 6 yes Figure 1 The diagram shows a front sectional view of a secondary battery.

[0028] Figure 7 This is a cross-sectional view of the negative electrode plate.

[0029] Figure 8 This is the front view of the negative electrode plate.

[0030] Figure 9 This is a cross-sectional view of the positive electrode plate.

[0031] Figure 10 This is the front view of the positive electrode plate.

[0032] Figure 11 yes Figure 1 The XI-XI cross-sectional view of the secondary battery shown.

[0033] Figure 12 yes Figure 1 The XII-XII cross-sectional view of the secondary battery is shown.

[0034] Figure 13 This is a flowchart illustrating a method for manufacturing a secondary battery according to one embodiment.

[0035] Figure 14 This is a perspective view showing the state of a secondary battery according to one embodiment before the two electrode bodies overlap.

[0036] Figure 15 yes Figure 14 The XV-XV cross-sectional view of the electrode body and the current collector is shown.

[0037] Figure 16 It is a three-dimensional view showing the state in which the electrode body is equipped with support members and isolation objects.

[0038] Figure 17 It is a three-dimensional diagram showing the current collector on the negative side with a sealing plate installed.

[0039] Figure 18 yes Figure 17 The XVIII-XVIII sectional view of the electrode body and the current collector shown.

[0040] Figure 19 It is a three-dimensional diagram showing the current collector on the positive side with a sealing plate installed.

[0041] Figure 20 It is a three-dimensional diagram showing the structure of a secondary battery.

[0042] Figure 21 This diagram illustrates the process of joining electrode tabs together using a horn and an anvil.

[0043] Figure 22 This is a diagram illustrating an example of the arrangement of welding heads in the electrode tab joining process.

[0044] Figure 23 This diagram illustrates the configuration of the welding head and anvil in the electrode tab joining process.

[0045] Figure 24 It is a 3D view of the welding head.

[0046] Figure 25 This is a top view showing the configuration of the weld heads in the joint.

[0047] Figure 26 This is a top view showing the configuration of the anvil in the joint.

[0048] Figure 27 This diagram shows an electrode tab assembly formed by joining electrode tabs together using a welding head and an anvil.

[0049] Figure 28This is a diagram showing the periphery of the junction in the electrode tab assembly.

[0050] Figure 29 yes Figure 28 XXIX-XXIX sectional view.

[0051] Figure 30 yes Figure 28 XXX-XXX sectional view.

[0052] Figure 31 This is a cross-sectional view showing the joint.

[0053] Figure 32 This is a cross-sectional view showing another example of a joint.

[0054] Figure 33 This is a cross-sectional view showing another example of a joint.

[0055] Figure 34 This is a top view (1) showing a modified example of the configuration of the anvil in the joint.

[0056] Figure 35 This is a top view (2) showing a modified example of the configuration of the anvil in the joint. Detailed Implementation

[0057] The following describes the implementation of this technology. Sometimes, the same or equivalent parts are labeled with the same reference numerals in the accompanying drawings, and their descriptions will not be repeated.

[0058] In the embodiments described below, when numbers or quantities are mentioned, the scope of this technology is not necessarily limited to those numbers or quantities unless specifically stated otherwise. Furthermore, in the embodiments described below, each constituent element is not necessarily essential to this technology unless specifically stated otherwise. Additionally, this technology is not necessarily limited to performing all the effects mentioned in these embodiments.

[0059] In this specification, the terms "comprise," "include," and "have" are open-ended. That is, when a certain component is included, other components besides that component may be included, or other components besides that component may not be included.

[0060] Furthermore, in this specification, when using geometric terms and terms indicating positional or directional relationships, such as "parallel," "orthogonal," "tilted at 45°," "coaxial," and "along," these terms are permissible with manufacturing errors or slight variations. In this specification, when using terms indicating relative positional relationships such as "upper side" and "lower side," these terms are used to indicate the relative positional relationship in a given state. Depending on the orientation of each mechanism (e.g., reversing the entire mechanism vertically), the relative positional relationship can be reversed or rotated to any angle.

[0061] Furthermore, the dimensions of the components illustrated in this specification, such as width, length, and diameter, are not limited to those shown in the illustrations and may be appropriately changed. In this specification, components are sometimes labeled with numbers such as "1st," "2nd," etc., but except where explicitly specified, these numbers do not imply priority or order.

[0062] In this specification, "battery" is not limited to lithium-ion batteries, but may also include other batteries such as nickel-metal hydride batteries and sodium-ion batteries. In this specification, the positive and negative electrodes may be collectively referred to as "electrodes." Additionally, the positive and negative plates may be collectively referred to as "electrode plates."

[0063] 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 units or capacitor modules.

[0064] Battery cells can be used 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 vehicle applications.

[0065] In this specification, the X direction is sometimes referred to as the "width direction" of the secondary battery, electrode body, and housing body, the Z direction is referred to as the "height direction" of the secondary battery or housing body, and the Y direction is referred to as the "thickness direction" of the secondary battery or housing body.

[0066] (The overall structure of a secondary battery)

[0067] Reference Figures 1 to 6The overall structure of the secondary battery 1 is described below. The secondary battery 1 includes a casing 100, an electrode body 200, electrode terminals 300, and a current collector 400. The casing 100 includes a casing body 110, a sealing plate 120, and a sealing plate 130.

[0068] When constructing a battery pack including secondary batteries 1, multiple secondary batteries 1 are stacked along their thickness direction. The stacked secondary batteries 1 can be constrained along the stacking direction (Y direction) by a constraining member to become a battery module, or the battery pack can be directly supported on the side of the battery pack housing without using a constraining member.

[0069] The housing body 110 is composed of a cylindrical component, preferably a square cylindrical component. This results in a square secondary battery 1. The housing body 110 is made of metal. Specifically, the housing body 110 is made of aluminum, aluminum alloy, iron, or iron alloy, etc.

[0070] like Figure 1 as well as Figure 2 As shown, sealing plates 120 and 130 are respectively provided at both ends of the housing body. The housing body 110 can be constructed, for example, by having the end edges of bent plate-like components abut against each other. Figure 2 The illustrated joint 115 is joined together (e.g., by laser welding or other energy line irradiation) to form a square tube shape. The corners of the "square tube" may have rounded shapes. The secondary battery in this technology is not necessarily limited to a square secondary battery.

[0071] In this embodiment, the housing body 110 is formed to be longer in the width direction (X direction) than in the thickness direction (Y direction) and height direction (Z direction) of the secondary battery 1. The width of the housing body 110 in the X direction is preferably 30 cm or more. This allows for the construction of a relatively large (high-capacity) secondary battery 1. The height of the housing body 110 in the Z direction is preferably 20 cm or less, more preferably 15 cm or less, and even more preferably 10 cm or less. This allows for the construction of a relatively low-height secondary battery 1, for example, improving vehicle mountability.

[0072] The housing body 110 includes a pair of first side faces 111 and a pair of second side faces 112. The pair of first side faces 111 form part of the side faces of the housing 100. The pair of second side faces 112 form the bottom and top surfaces of the housing 100. The pair of first side faces 111 and the pair of second side faces 112 are arranged in a mutually intersecting manner. The pair of first side faces 111 and the pair of second side faces 112 are connected at their respective ends. Preferably, the area of ​​each of the pair of first side faces 111 is larger than the area of ​​each of the pair of second side faces 112.

[0073] like Figure 5 As shown, an exhaust valve 150 is provided on one of the pair of second side portions 112, on the second side portion 112A. The exhaust valve 150 extends along the width direction (X direction) of the secondary battery 1. The exhaust valve 150 extends along the X direction to a degree that it does not reach either end from the center of the housing body 110 in the X direction. The shape of the exhaust valve 150 can be appropriately modified.

[0074] The thickness of the plate-shaped component in the exhaust valve 150 is thinner than the thickness of the plate-shaped components other than the exhaust valve 150 in the housing body 110. As a result, when the pressure inside the housing 100 becomes above a predetermined value, the exhaust valve 150 breaks first than other parts in the housing body 110, venting the gas inside the housing 100 to the outside.

[0075] like Figure 2 As shown, a joining portion 115 is formed on the other of the pair of second side portions 112B. The joining portion 115 extends along the width direction (X direction) of the secondary battery 1. At the joining portion 115, the end edges of the plate-shaped members constituting the housing body 110 are joined together.

[0076] like Figure 3 As shown, an opening 113 (first opening) is provided at one end of the housing 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 generally rectangular shape with the short side in the Y direction and the long side in the Z direction. The generally rectangular shape includes a rectangular shape or a shape with rounded corners, etc., that is substantially rectangular.

[0077] A negative terminal 301 (first electrode terminal) is provided on the sealing plate 120. The position of the negative terminal 301 can be changed as appropriate.

[0078] like Figure 4 As shown, an opening 114 (second opening) is provided at the end of the housing body 110 on the opposite side 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 are opposite to 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 generally rectangular shape with the short side in the Y direction and the long side in the Z direction.

[0079] A positive terminal 302 (second electrode terminal) and an injection hole 134 are provided on the sealing plate 130. The injection hole 134 only needs to be large enough to inject electrolyte into the interior of the housing 100, and is preferably smaller than the insertion hole of the positive terminal 302 provided on the sealing plate 130. Preferably, the injection hole 134 is offset from the center of the sealing plate 130 in the Z direction. The positions of the positive terminal 302 and the injection hole 134 can be appropriately changed.

[0080] Sealing plates 120 and 130 are made of metal. Specifically, sealing plates 120 and 130 are made of aluminum, aluminum alloy, iron, or iron alloy.

[0081] The negative terminal 301 is electrically connected to the negative terminal of the electrode body 200 (the first electrode). The negative terminal 301 is mounted on the sealing plate 120, i.e., the housing 100.

[0082] The positive terminal 302 is electrically connected to the positive terminal (second electrode) of the electrode body 200. The positive terminal 302 is mounted on the sealing plate 130, i.e., the housing 100.

[0083] The negative terminal 301 may be made of a conductive material (more specifically, a metal), such as copper or a copper alloy. Alternatively, a portion or layer made of aluminum or an aluminum alloy may be provided on the outer surface of the negative terminal 301.

[0084] The positive terminal 302 may be made of a conductive material (more specifically a metal), such as aluminum or an aluminum alloy.

[0085] The injection port 134 is sealed by a sealing component (not shown). Such sealing components can be, for example, blind rivets or other metal parts.

[0086] The electrode body 200 is a flat electrode body formed by stacking the negative electrode plate and the positive electrode plate described later. Specifically, the electrode body 200 is a stacked electrode body formed by alternately stacking multiple negative electrode plates and multiple positive electrode plates with a separator in between. The separator can be a separator made by folding a strip-shaped insulating sheet component into a serrated shape, or it can be a separator with multiple insulating sheets separately provided. In this specification, "electrode body" is not limited to a stacked electrode body, and it can also be a wound electrode body formed by winding strip-shaped negative electrode plates and strip-shaped positive electrode plates together with a strip-shaped separator in between. The separator can be, for example, made of a polyolefin microporous membrane. When the electrode body is a stacked electrode body including multiple negative electrode plates and multiple positive electrode plates, negative electrode tabs (first electrode tabs) disposed on each negative electrode plate can be stacked to form a negative electrode tab group, and positive electrode tabs (second electrode tabs) disposed on each positive electrode plate can be stacked to form a positive electrode tab group.

[0087] like Figure 6As shown, the housing 100 houses the electrode body 200. Figure 6 The first electrode 201, described later, is illustrated in the diagram. The first electrode 201 is housed within the housing 100 with its long side parallel to the X direction.

[0088] Specifically, one or more stacked electrode bodies are housed inside the insulating sheet 700 (described later) disposed within the housing 100, along with an electrolyte (not shown). As the electrolyte (non-aqueous electrolyte), for example, an electrolyte in which LiPF6 is dissolved at a concentration of 1.2 mol / L can be used, consisting of a non-aqueous solvent composed of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) mixed in a volume ratio (25°C) of 30:30:40. A solid electrolyte can also be used instead of the electrolyte.

[0089] The electrode body 200 includes a first electrode body 201. The first electrode body 201 includes a generally rectangular main body, a negative electrode tab group 220, and a positive electrode tab group 250.

[0090] 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 assembly 220 is located at the end of the main body on one side (the sealing plate 120 side) of the first electrode body 201 in the X direction. The positive electrode tab assembly 250 is located at the end of the main body on the other side (the sealing plate 130 side) of the first electrode body 201 in the X direction.

[0091] The negative electrode tab group 220 and the positive electrode tab group 250 are formed in such a way that they protrude from the central portion of the electrode body 200 toward the sealing plate 120 or the sealing plate 130, respectively.

[0092] The current collector 400 includes a negative current collector 400A and a positive current collector 400B. The negative current collector 400A and the positive current collector 400B are each composed of plate-shaped components. The electrode body 200 is electrically connected to the negative terminal 301 and the positive terminal 302 via the current collector 400.

[0093] The negative current collector 400A is disposed on the sealing plate 120 via a resin insulating component. The negative current collector 400A is electrically connected to the negative electrode tab assembly 220 and the negative terminal 301. The negative current collector 400A may be made of a conductive material (more specifically, a metal), such as copper or a copper alloy. Details regarding the negative current collector 400A will be described later.

[0094] The positive current collector 400B is disposed on the sealing plate 130 via a resin insulating component. The positive current collector 400B is electrically connected to the positive electrode tab assembly 250 and the positive terminal 302. The positive current collector 400B may be made of a conductive material (more specifically, a metal), such as aluminum or an aluminum alloy. Alternatively, the positive electrode tab assembly 250 may be electrically connected to the sealing plate 130 directly or via the positive current collector 400B. In this case, the sealing plate 130 can function as the positive terminal 302. Details regarding the positive current collector 400B will be described later.

[0095] (Composition of electrode body 200)

[0096] like Figure 7 as well as Figure 8 As shown, a negative electrode tab 230, composed 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 assembly 220. The negative electrode tab assembly 220 is electrically connected to the negative electrode. The length of each negative electrode tab 230 in the protruding direction of the multiple negative electrode plates 210 is appropriately adjusted considering the connection state between the negative electrode tab assembly 220 and the negative current collector 400A. The shape of the negative electrode tab 230 is not limited to... Figure 8 The illustrated shape.

[0097] like Figure 9 as well as Figure 10 As shown, a positive electrode tab 260, composed 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 assembly 250. The positive electrode tab assembly 250 is electrically connected to the positive electrode. The length of each positive electrode tab 260 in the protruding direction among the multiple positive electrode plates 240 is appropriately adjusted considering the connection state between the positive electrode tab assembly 250 and the positive current collector 400B. The shape of the positive electrode tab 260 is not limited to... Figure 10 The illustrated shape.

[0098] A positive electrode protective layer 243 is provided at the base of the positive electrode tab 260. It is not necessary to provide a positive electrode protective layer 243 at the base of the positive electrode tab 260.

[0099] In a typical example, the thickness of the negative electrode tab 230 (one) is less than the thickness of the positive electrode tab 260 (one). In this case, the thickness of the negative electrode tab group 220 is less than the thickness of the positive electrode tab group 250.

[0100] (Connection structure between electrode 200 and current collector 400)

[0101] Reference Figure 11 as well as Figure 12The connection structure between the electrode body 200 and the current collector 400 will be explained.

[0102] like Figure 11 , Figure 12 As shown, the electrode body 200 includes a first electrode body 201 and a second electrode body 202. The first electrode body 201 and the second electrode body 202 respectively include a positive electrode and a negative electrode. The electrode body 200 may also be composed of three or more electrode bodies.

[0103] Electrode 200 is formed by overlapping the first electrode 201 and the second electrode 202. The first electrode 201 and the second electrode 202 are arranged along the thickness direction (Y direction) of the first electrode 201 and the second electrode 202.

[0104] like Figure 11 (As shown in the connection structure on the negative electrode side), the first electrode body 201 includes a negative electrode tab assembly 220. The negative electrode tab assembly 220 is electrically connected to the current collector 410 (negative current collector) at its first end 205 in the X direction. The second electrode body 202 includes a negative electrode tab assembly 270. The negative electrode tab assembly 270 is electrically connected to the current collector 410 (negative current collector) at its third end 207 in the X direction.

[0105] The negative electrode tab assembly 220 has a bent portion 221 and a front end portion 222. The bent portion 221 is the bent part of the negative electrode tab assembly 220. The front end portion 222 is the part located at the end of the negative electrode tab assembly 220.

[0106] The negative electrode tab assembly 270 has a bent portion 271 and a front end portion 272. The bent portion 271 is the bent part of the negative electrode tab assembly 270. The front end portion 272 is the part located at the end of the negative electrode tab assembly 270.

[0107] The negative electrode tab group 220 and the negative electrode tab group 270 are bent in opposite directions with their front ends 222 and 272 approaching each other. In this embodiment, the front ends 222 and 272 are separated, but this configuration is not limited to this; the front ends 222 and 272 may also contact each other.

[0108] The negative current collector 400A electrically connects the negative terminal 301 to the negative electrode tab group 220 and the negative electrode tab group 270. In this embodiment, the negative current collector 400A is connected to the negative terminal 301 between the electrode body 200 and the sealing plate 120. The negative current collector 400A includes a current collector 410 and a current collector 430.

[0109] Current collector 410 is a plate-shaped component. Current collector 410 has a long side in the Z direction and a short side in the Y direction. Current collector 410 is constructed as a single, integral component. Current collector 430 is also a plate-shaped component. Current collector 430 has a long side in the Z direction and a short side in the Y direction. Current collectors 410 and 430 are arranged side-by-side in the X direction. Thus, current collectors 410 and 430 are constructed as independent components.

[0110] Negative electrode tabs 220 and 270 are described later (see reference). Figure 15 The joint portion 411 is joined to the current collector 410. The joint portion 411 can be formed, for example, by laser welding.

[0111] The current collector 430 is joined to the current collector 410 at the joint at its end located in the Z direction. 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 seam sealing and / or welding.

[0112] The negative terminal 301 is exposed on the outside of the sealing plate 120. The negative terminal 301 is connected to the plate-shaped component 303. The negative terminal 301 includes a region 301A made of copper or copper alloy and a region 301B made of aluminum or aluminum alloy. Preferably, the region 301A made of copper or copper alloy is connected to the current collector 430.

[0113] The plate-shaped component 303 is located on the outside of the sealing plate 120. The plate-shaped component 303 is arranged along the sealing plate 120. The plate-shaped component 303 is conductive. The plate-shaped component 303 is arranged to ensure the connection area with the busbar, etc., that electrically connects the secondary battery 1 and other adjacent secondary batteries. The connection between the negative terminal 301 and the plate-shaped component 303 can be formed, for example, by laser welding.

[0114] An insulating component 510 is disposed between the plate-shaped component 303 and the sealing plate 120. An insulating component 520 is disposed between the negative terminal 301 and the sealing plate 120. An insulating component 530 is disposed between the current collector 430 and the sealing plate 120.

[0115] However, the negative terminal 301 can also be electrically connected to the sealing plate 120. The sealing plate 120 can function as the negative terminal 301.

[0116] A spacer 600 is disposed between the sealing plate 120 and the main body of the electrode body 200 (excluding the negative electrode tabs 220 and 270). The spacer 600 is made of an insulating resin component. The spacer 600 inhibits the movement of the electrode body 200 within the housing 100 in the X direction and inhibits damage to the negative electrode tabs 220, negative electrode tabs 270, and the electrode body 200.

[0117] like Figure 12 (Connection structure on the positive side) As shown, the connection structure between the electrode body 200 and the current collector 400 on the positive side is different from that on the negative side in that the part corresponding to the current collector 410 on the negative side is composed of two parts.

[0118] The first electrode 201 includes a positive electrode tab assembly 250. The positive electrode tab assembly 250 is electrically connected to the current collector 420 (positive current collector) at its second end 206 in the X direction. The second electrode 202 includes a positive electrode tab assembly 280. The positive electrode tab assembly 280 is electrically connected to the current collector 420 at its fourth end 208 in the X direction.

[0119] The positive electrode tab assembly 250 has a bent portion 251 and a front end portion 252. The bent portion 251 is the bent part of the positive electrode tab assembly 250. The front end portion 252 is the part located at the end of the positive electrode tab assembly 250.

[0120] The positive electrode tab assembly 280 has a bent portion 281 and a front end portion 282. The bent portion 281 is the bent part of the positive electrode tab assembly 280. The front end portion 282 is the part located at the end of the positive electrode tab assembly 280.

[0121] The positive electrode tab group 250 and the positive electrode tab group 280 are bent in opposite directions with their front ends 252 and 282 approaching each other. In this embodiment, the front ends 252 and 272 are separated, but this configuration is not limited to this; the front ends 252 and 282 may also be in contact with each other.

[0122] The positive current collector 400B electrically connects the positive terminal 302 to the positive electrode tab group 250 and the positive electrode tab group 280. In this embodiment, the positive current collector 400B is connected to the positive terminal 302 between the electrode body 200 and the sealing plate 130.

[0123] The positive current collector 400B includes a current collector 420 and a current collector 440. An insulating member 460 is sandwiched between the current collector 420 and the current collector 440, but is electrically connected at a location different from the cross-section shown in the figure.

[0124] The current collector 420 is a plate-shaped component. The current collector 420 has a long side in the Z direction and a short side in the Y direction. The current collector 420 consists of one current collector and another current collector; that is, the current collector 420 is composed of two components.

[0125] The positive electrode tab assembly 250 and the positive electrode tab assembly 280 are joined at the junction 421 described later (see reference). Figure 15 The junction 421 is joined to the current collector 420, which is composed of two components. The junction 421 can be formed, for example, by laser welding.

[0126] The current collector 440 is joined to the current collector 420 at the joint at its end located in the Z direction. 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 seam sealing and / or welding.

[0127] The positive terminal 302 is exposed on the outside of the sealing plate 130 and is positioned such that it reaches the current collector 440 of the positive current collector 400B disposed on the inner surface of the sealing plate 130. The positive terminal 302 is connected to the plate-shaped member 304.

[0128] The plate-shaped component 304 is located on the outside of the sealing plate 130. The plate-shaped component 304 is arranged along the sealing plate 130. The plate-shaped component 304 is conductive. The plate-shaped component 304 is arranged to ensure the connection area of ​​the busbar, etc., which electrically connects the secondary battery 1 and other adjacent secondary batteries. The connection between the positive terminal 302 and the plate-shaped component 304 can be formed, for example, by laser welding.

[0129] An insulating component 510 is disposed between the plate-shaped component 304 and the sealing plate 130. An insulating component 520 is disposed between the positive terminal 302 and the sealing plate 130. An insulating component 470 is disposed between the current collector 440 and the sealing plate 130.

[0130] However, the positive terminal 302 can also be electrically connected to the sealing plate 130. The sealing plate 130 can function as the positive terminal 302.

[0131] A spacer 600 is disposed between the sealing plate 130 and the main body of the electrode body 200 (excluding the positive electrode tabs 250 and 280). The spacer 600 is made of an insulating resin component. The spacer 600 inhibits the movement of the electrode body 200 within the housing 100 in the X direction and inhibits damage to the positive electrode tabs 250 and 280, as well as the electrode body 200.

[0132] Figure 11 as well as Figure 12 The separator 600 shown is, for example, made of resin. The material of the separator 600 is, for example, polypropylene (PP), polyphenylene sulfide (PPS), polybutylene terephthalate (PBT), or ethylene propylene rubber (EPDM).

[0133] like Figure 11 as well as Figure 12 As shown, a resin insulating sheet 700 (electrode support) is disposed between the electrode body 200 and the housing body 110. The insulating sheet 700 may be made of resin, for example. More specifically, the insulating sheet 700 may be made of polypropylene (PP), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyimide (PI), or polyolefin (PO).

[0134] (Manufacturing process of secondary battery 1)

[0135] The following uses Figure 13 The flowchart below describes the manufacturing method of the secondary battery according to this embodiment. In the manufacturing method of the secondary battery according to this embodiment, the first electrode body 201 and the second electrode body 202 are first manufactured (S1 step). Preferably, a portion of the front end 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 off so that the length of the front end is the same during bundling.

[0136] like Figure 14 as well as Figure 15 As shown, after the first electrode body 201 and the second electrode body 202 are fabricated, the positive electrode tabs 250 and 280 are joined to the current collector 420 (S2 process). The positive electrode tabs 250 and 280 are joined to the current collector 420 at the joining portion 421.

[0137] Next, the first electrode 201, the current collector 410, and the second electrode 202 are arranged sequentially along the DR1 direction. A negative electrode tab assembly 220 is arranged on one side of the current collector 410 along the DR1 direction. With the negative electrode tab assembly 270 arranged on the other side of the current collector 410 along the DR1 direction, the negative electrode tab assembly 220 and the negative electrode tab assembly 270 are joined to the current collector 410 (step S3). The negative electrode tab assembly 220 and the negative electrode tab assembly 270 are joined to the current collector 410 at the joining portion 411.

[0138] In the height direction of the first electrode 201 and the second electrode 202, the current collectors 410 and 420 are disposed offset to one side from the center of the first electrode 201 and the second electrode 202. Therefore, since the current collectors can be made shorter, they can be made smaller. The current collectors 410 and 420 are not limited to this configuration. The current collectors 410 and 420 may also be disposed at the center of the first electrode 201 and the second electrode 202 in the height direction.

[0139] The order of the processes for connecting the first electrode 201 and the second electrode 202 to the current collector 410 and the current collector 420, respectively, is not limited to the above and can be changed. Preferably, the process of connecting the first electrode 201 and the second electrode 202 to the current collector 420 is performed before the process of aligning the first electrode 201 and the second electrode 202, which will be described later, and preferably before the process of connecting the first electrode 201 and the second electrode 202 to the current collector 410.

[0140] Next, after the negative electrode tab group 220 and the negative electrode tab group 270 are joined to the current collector 410, in the thickness direction of the first electrode body 201 and the second electrode body 202 ( Figure 17 as well as Figure 18 In the direction orthogonal to DR1, the negative electrode tab group 220 and the negative electrode tab group 270 are bent so that the first electrode body 201 and the second electrode body 202 overlap (S4 process). That is, the first electrode body 201 and the second electrode body 202 are brought together.

[0141] "Making the first electrode and the second electrode overlap" can mean that the first electrode and the second electrode are directly overlapped, or that other components are placed between the first electrode and the second electrode. The first electrode and the second electrode can be fixed by tape or the like, or they can be left unfixed. Furthermore, the first electrode, the current collector, and the second electrode can be arranged in a non-linear manner in the DR1 direction, or the first electrode or the second electrode can be tilted relative to the DR1 direction with respect to the current collector.

[0142] Negative electrode tabs 220 and 270 are bent with their front ends facing each other. Positive electrode tabs 250 and 280 are also bent with their front ends facing each other.

[0143] Next, as Figure 16 As shown, the separator 600 and the insulating sheet 700 are assembled onto the electrode body 200 (step S5). After assembling the separator 600 on both the negative and positive sides of the electrode body 200, the electrode body 200 and the separators 600 on both sides are covered with the insulating sheet 700. Thus, with the separators 600 positioned on both sides of the electrode body 200, the electrode body 200 and the separators 600 on both sides are covered with the insulating sheet 700. The insulating sheet 700 is fixed to the separators 600 on both sides.

[0144] Next, as Figure 17 as well as Figure 18 As shown, current collector 410 is electrically connected to negative terminal 301 via current collector 430 (step S6). Step S6 can also be performed before step S5. Specifically, as... Figure 18 As shown, the negative electrode tab group 220 and the negative electrode tab group 270 are bent so that their front ends 222 and 272 are opposite to each other.

[0145] The negative terminal 301 and the current collector 430 are mounted to the sealing plate 120 via an insulating component. The current collector 430 and the current collector 410 are brought into contact in the X direction. The connection of the plate-shaped component 303 to the negative terminal 301 can be made at any time. The current collector 430 and the current collector 410 are joined by laser welding between the sealing plate 120 and the insulating sheet 700.

[0146] Next, with the current collector 420 side as the front end, the spacer 600 and the electrode 200 are inserted into the housing body 110 through the opening 113 (step S7). Then, by bringing the sealing plate 120 close to the main body of the electrode 200 (first electrode 201 and second electrode 202) from the state of extending from the negative electrode tab group 220 and the negative electrode tab group 270, the negative electrode tab group 220 and the negative electrode tab group 270 are bent. Figure 11 (As shown in the diagram). The negative electrode tab assembly 220 and the negative electrode tab assembly 270 are bent along the shape of the separator 600 in such a way that the folded-back portions of the bends 221 and 271 approach the housing body 110 in the Y direction.

[0147] like Figure 19 As shown, after the sealing plate 120 abuts against the housing body 110, the sealing plate 120 is pre-joined to the housing body 110. Through pre-joining, the sealing plate 120 is partially joined to the opening 113 of the housing body 110. Thus, the sealing plate 120 is positioned relative to the housing body 110.

[0148] When the electrode body 200 is inserted into the housing body 110, the electrode body 200 can be pulled from the current collector 420 side or pressed from the current collector 410 side. When the electrode body 200 is pressed from the current collector 410 side, both the negative electrode tab group 220 and the negative electrode tab group 270 can be bent simultaneously.

[0149] After the electrode body 200 is inserted into the housing body 110, the current collector 420 is electrically connected to the positive terminal 302 (step S8). Specifically, the positive terminal 302 is mounted to the sealing plate 130 via an insulating member. After the first electrode body 201 and the second electrode body 202 are inserted into the housing body 110, the current collector 440 abuts against 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 made at any time.

[0150] The positive electrode tab group 250 and positive electrode tab group 280 connected to the current collector 420 are bent so that their front ends 252 and 282 are opposite to each other. Figure 12 As shown, the positive electrode tabs 250 and 280 are bent along the shape of the separator 600 such that the folded-back portions of the bends 251 and 281 approach the housing body 110 in the Y direction.

[0151] After inserting the separator 600 and the electrode body 200 into the housing body 110, the sealing plate 130 and the sealing plate 120 are joined to the housing body 110 (S9 process).

[0152] like Figure 20 As shown, after the sealing plate 130 abuts against the housing body 110, the sealing plate 130 is pre-welded to the housing body 110. Through pre-joining, the sealing plate 130 is partially joined to the opening 114 of the housing body 110. Thus, the sealing plate 130 is positioned relative to the housing body 110.

[0153] Next, sealing plates 120 and 130 are joined to the housing body 110. Sealing plate 120 seals the opening 113 of the housing body 110, and sealing plate 130 seals the opening 114 of the housing body 110. Thus, the first electrode 201 and the second electrode 202 are housed in the housing 100.

[0154] After the above-described processes, leak checks and other inspections are performed (S10 process). After the leak check, the secondary battery 1 is dried in order to remove moisture from the casing 100.

[0155] Next, electrolyte is injected into the housing 100 through the injection hole 134 provided on the sealing plate 130, with the sealing plate 130 positioned higher than the sealing plate 120 in the vertical direction and the separator 600 positioned below the electrode body 200 (step S11). Because the separator 600 is provided around the injected electrolyte, damage to the electrode body 200 and the like can be suppressed even if the electrolyte is forcefully injected into the housing 100. Therefore, the secondary battery 1 of this embodiment can inject electrolyte in a shorter time compared to the case where the separator 600 is not provided. Then, venting and charging are performed. During venting and charging, the injection hole 134 can be pre-sealed. Then, the injection hole 134 is sealed, and the secondary battery 1 is completed.

[0156] (The connection between the electrode tabs)

[0157] Next, the connection between the electrode tabs in the electrode tab assembly will be explained. For example... Figure 21 As shown, the negative electrode tabs 230 (first electrode tabs) are joined together using the welding head 10 and the anvil 20 to form a negative electrode tab group 220 (first electrode tab group). At this time, the welding head 10 presses the negative electrode tabs 230 in the direction of arrow B while vibrating in the direction of arrow A. Wherein, in Figure 21 An example is shown where four tabs are stacked, but the number of stacked tabs is preferably five or more, more preferably ten or more, and even more preferably twenty or more.

[0158] like Figure 22As shown, when forming a joint in the negative electrode tab assembly 220, the welding head 10 is preferably located at the front end of the negative electrode tab assembly 220. This allows for more effective suppression of excessive load on the root N of the negative electrode tab (particularly the root of the negative electrode tab 230 located near the outermost edge in the stacking direction), thus preventing damage to the root of the negative electrode tab 230. For example, it is preferable that the entire welding head 10 abuts against the area within one-third of the length of the longest negative electrode tab 230 in the negative electrode tab assembly 220, starting from the front end of the negative electrode tab 230.

[0159] like Figure 23 , Figure 24 As shown, the welding head 10 includes linear protrusions 11 (first protrusions), a base surface 12, a protrusion 13, and a body 14. Multiple linear protrusions 11 are formed extending substantially parallel to each other (in substantially the same direction). The linear protrusions 11 are preferably straight, but can also be curved. When viewed from above (when viewed from a direction perpendicular to the base surface), the ratio (L / B) of the length L of the protrusion 11 (the length along the curve in the case of a curved protrusion) to the width B of the protrusion 11 is preferably about 3 or more, more preferably about 5 or more, and even more preferably about 10 or more.

[0160] In this manner, as a plurality of linear protrusions 11 extend in substantially the same direction, the inclination of one linear protrusion 11 relative to the other linear protrusions 11 is preferably within ±15 degrees, more preferably within ±10 degrees, and even more preferably within ±5 degrees.

[0161] The protrusion 11 is provided such that it projects from the base surface 12. The top of the protrusion 11 extends in a linear shape. Figure 23 , Figure 24 In this example, multiple (3) protrusions 11 are provided, but the number of protrusions 11 can be appropriately varied. A single protrusion 11 can also be present. The base surface 12 forms the upper surface of the protrusion 13. Figure 23 , Figure 24 In this example, the base surface 12 is a flat surface. The protrusion 13 is provided to project out of the body 14. The protrusion 13 has curved sides, and its length and width gradually decrease as it moves away from the body 14. Furthermore, the shape of the protrusion 13 is not limited to this.

[0162] In the process of forming the joint of the negative electrode tabs 230, vibration (e.g., ultrasonic vibration) is applied with the protrusion 11 abutting against the negative electrode tab assembly 220. At this time, the welding head 10 vibrates in a direction that is approximately orthogonal (intersecting) to the direction in which the linear protrusion 11 extends. The linear protrusion 11 does not necessarily have to be approximately orthogonal to the vibration direction. Preferably, the protrusion 11 intersects the vibration direction at an angle of about 90° ± 30° or less, and more preferably at an angle of about 90° ± 15° or less.

[0163] like Figure 25 As shown, the linear protrusion 11 in the welding head 10 is positioned near the center of the joint portion 411. Figure 26 As shown, the anvil 20 has a flat region 21 (first region) opposite to the protrusion 11 and a protrusion forming region 22 (second region) disposed around the periphery of the flat region 21. Multiple protrusions (second protrusions) are formed in the protrusion forming region 22. The protrusions of the anvil 20 formed in the protrusion forming region 22 may not be linear protrusions; for example, they may be a pyramidal shape with an aspect ratio (major axis length / minor axis length) less than 2 when viewed from above (when viewed from a direction perpendicular to the contact surface of the negative electrode tab assembly 220), or they may be conical, hemispherical, etc. Preferably, one protrusion (second protrusion) formed in the protrusion forming region 22 of the anvil 20, when viewed from above ( Figure 26 The area (the area surrounded by the outline of the root portion of each protrusion when viewed along the protruding direction) is less than that of one protrusion 11 (the first protrusion). For example, it is preferable that the ratio of (area of ​​a second protrusion) to (area of ​​a first protrusion) is about 0.5 or less, more preferably about 0.3 or less, and even more preferably about 0.1 or less.

[0164] The flat area 21 of the anvil 20 may have minute irregularities, such as those found on the surface of the anvil 20 where no protrusions are formed. In the flat area 21, it is preferable that there are no protrusions with a height of about 0.03 mm or more, and more preferably that there are no protrusions with a height of about 0.01 mm or more.

[0165] The flat area 21 of the anvil 20, for example a quadrilateral area of ​​3mm × 5mm, is preferably formed to include at least an area without protrusions (except for the aforementioned minor unevenness). More preferably, it is formed to include at least an area of ​​3mm × 8mm quadrilateral without protrusions.

[0166] 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.

[0167] like Figure 27As shown, a recess 2201A is formed at the junction 411 of the negative electrode tab assembly 220 and the current collector 410. The recess 2201A is formed to extend in a direction (Z direction) orthogonal to the protruding direction (X direction) of the negative electrode tab assembly 220 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.

[0168] like Figure 28 or Figure 30 As shown, a recess 2201A (first recess) as an indentation of a protrusion 11 and a recess 2202A (second recess) as an indentation of a convex portion 13 are formed on the outer surface (first outer surface) of one of the negative electrode tabs 220.

[0169] A recess 2201A is formed at the bottom of a 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) surrounding region 2201B, the negative electrode tabs 230 are bonded to each other with a relatively weaker bonding strength than in region 2201B. Furthermore, in a portion of region 2201B, there may be areas where the negative electrode tabs 230 are not bonded to each other.

[0170] exist Figure 29 , Figure 30 In the example shown, the sidewall of the recess 2202A is inclined toward the opening in a direction that widens the recess 2202A. The inclination of the sidewall 2201C (first sidewall), which extends in the same direction as the linear recess 2201A (see reference...) Figure 29 The inclination is relative to the sidewalls 2202C (second sidewalls) located at both ends of the linear recess 2201A (see reference). Figure 30 The slope is gentle (the angle of intersection with the bottom surface of the recess 2202A is small). However, the inclination of the sidewall of the recess 2202A is not limited to the example described above.

[0171] After the negative electrode tabs 230 are joined together, the negative electrode tab assembly 220 is joined to the current collector 410 (the first conductive member). At this time, the current collector 410 is positioned opposite to the surface of the recess 2201A (region 2201B) where an indentation as a protrusion 11 is formed. Figure 28 The negative electrode tab assembly 220 (the inner side of the paper) abuts against the outer surface (second outer surface), so that the current collector 410 can be overlapped with the portion abutting the flat area 21 of the anvil 20. In this state, by moving from the recess 2201A side ( Figure 28 The paper surface near the front is irradiated with a laser (energy line), causing the negative electrode tab group 220 to connect with the current collector 410.

[0172] Macroscopically, the laser scans in a direction that is approximately orthogonal (intersecting) to the extending direction of the recess 2201A (region 2201B). Therefore, the laser-welded portion 411A, which joins the negative electrode tab assembly 220 to the current collector 410, extends in a direction that is approximately orthogonal (intersecting) to the extending direction of the recess 2201A (region 2201B). When using a laser as the energy line, it can be either a continuous oscillation type or a pulsed type.

[0173] By intersecting the extension direction of the laser-welded portion 411A with the extension direction of the recess 2201A (region 2201B), a region overlapping the laser-welded portion 411A and region 2201B of the negative electrode tab assembly 220 can be reliably formed. As a result, since region 2201B, where the negative electrode tabs 230 are more securely joined in the negative electrode tab assembly 220, and the current collector 410 can be joined more reliably, the reliability of the joint between the negative electrode tab assembly 220 and the current collector 410 is increased. Furthermore, necking during laser welding can be suppressed, improving the reliability of the electrical connection between the negative electrode tab assembly 220 and the current collector 410.

[0174] The laser used to join the negative electrode tab assembly 220 and the current collector 410 can irradiate only the bottom of the recess 2202A, or it can irradiate the bottom and sidewalls of the recess 2202A, or it can irradiate beyond the bottom and sidewalls of the recess 2202A to reach the outside of the recess 2202A. When the laser also irradiates the sidewalls of the recess 2202A, it is preferable that the inclination of the sidewall 2201C (first sidewall), which is the first part to be irradiated by the laser, is (see reference) Figure 29 ) compared to the second part of the sidewall 2202C (second sidewall) that was not irradiated by the laser (see reference) Figure 30 The slope is gentle.

[0175] According to the bonding process of this embodiment, since vibration can be applied while the negative electrode tab assembly 220 is stably held by the linear protrusion 11 formed on the welding head 10, the reliability of the bonding between the negative electrode tabs 230 can be improved. 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 protrusion 11 (first protrusion) of the welding head 10 may not necessarily be linear.

[0176] Furthermore, according to the joining process involved in this embodiment, by providing a flat region 21 on the anvil 20 that faces the protrusion 11 of the welding head 10 across the negative electrode tab assembly 220, the current collector 410 can be overlapped on the portion abutting the flat region 21. Therefore, laser welding can be performed on the portion where the gap between the negative electrode tab assembly 220 and the current collector 410 is small, effectively suppressing the generation of porosity during welding. As a result, the reliability of the joining between the negative electrode tab assembly 220 and the current collector 410 can be improved. As a result, a secondary battery 1 with high reliability can be obtained.

[0177] like Figure 31 As shown, a flat region 2203 (first region) is formed on the lower surface (second outer surface) opposite the recess 2201A (first recess) formed on the upper surface (first outer surface). Region 2203 corresponds to the region abutted by the flat region 21 of the anvil 20. By overlapping the current collector 410 onto 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 assembly 220 and the current collector 410 is small. A recess 2204A, which is an indentation caused by the protrusion of the anvil 20, is formed around region 2203.

[0178] like Figure 31 As illustrated, the depth of the recess 2201A (the indentation caused by the protrusion of the solder head) is preferably greater than the depth of the recess 2204A (the indentation caused by the protrusion of the anvil). The opening width of the recess 2201A (the indentation caused by the protrusion of the solder head) is preferably wider than the opening width of the recess 2204A (the indentation caused by the protrusion of the anvil). Furthermore, the number of recesses 2201A (the indentations caused by the protrusion of the solder head) is preferably less than the number of recesses 2204A (the indentations caused by the protrusion of the anvil). Therefore, each recess 2201A is relatively large, allowing for reliable irradiation of energy beams into the recess 2201A.

[0179] In the above example ( Figure 26 In the example, the protrusion forming region 22 of the anvil 20 is illustrated in a ring shape that surrounds the flat region 21. As a result, the foil misalignment of the negative electrode tabs 230 during ultrasonic vibration of the welding head 10 can be effectively suppressed, and a stable joint between the negative electrode tabs 230 can be formed.

[0180] When the protrusion-forming region 22 is formed in a ring shape to surround the flat region 21, the flat region 21 surrounded by the protrusion-forming region 22 is preferably visible when viewed from above ( Figure 26 It has 40mm 2 Above and around (more preferably 50mm) 2 The above and around, more preferably 80mm 2The area (S21) of the protrusion forming region 22 when viewed from above can be the same as or less than the area (S21) of the flat region 21. For example, the area (S22) of the protrusion forming region 22 when viewed from above can be 50 mm. 2 Below left or right or 40mm 2 The area to the left and right below. Here, the area (S22) of the protrusion forming region 22 when viewed from above is the area on the flat surface including the flat region 21, which is equivalent to the area of ​​the smallest region containing a group of protrusions arranged in a regular manner.

[0181] When the protrusion forming region 22 is formed in a ring shape to surround the flat region 21, the protrusions of the anvil 20 in the protrusion forming region 22 are preferably 160 per 10 mm. 2 The density is around 10mm. 2 (More than 160 protrusions are set in the area.)

[0182] Preferred view from above ( Figure 26 The protrusion 11 of the welding head 10 has an area of ​​about 0.5 × S11 or more (more preferably about 0.7 × S11 or more, and even more preferably about 0.9 × S11 or more) of its area (S11) and is opposite to the flat area 21 of the anvil 20. Further preferably, when viewed from above (… Figure 26 The entire area (area: S11) of the protrusion 11 of the welding head 10 is opposite to the flat area 21 of the anvil 20.

[0183] The configuration of the protrusion 11 of the welding head 10, the flat area 21 of the anvil 20, and the protrusion forming area 22 is not limited to Figure 26 The illustrated configuration. The flat area 21 does not necessarily have to be surrounded by the protrusion forming area 22. Furthermore, the protrusion 11 of the weld head 10 and a portion of the protrusion forming area 22 may be visible when viewed from above ( Figure 26 )overlapping.

[0184] like Figure 32 As shown, in the anvil 20, instead of the flat region 21 which is the first region, a region with a protrusion (third protrusion) can be provided, but the height of this protrusion is lower than the height of the protrusion (second protrusion) provided in the protrusion forming region 22 (the second region). This region, like the flat region 21, corresponds to the first region of the anvil 20. Figure 32In this example, a recess 2203A (third recess) is formed in the portion of the outer surface (second outer surface) of the negative electrode tab assembly 220 that abuts against the first region of the anvil 20, serving as an indentation 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 formation of a large gap between the outer surface of the negative electrode tab assembly 220 and the current collector 410, and to stably connect the negative electrode tab assembly 220 and the current collector 410.

[0185] For example, it is preferable that the height of the protrusion (third protrusion) formed in the first region of the anvil 20 is about 1 / 2 or less of the height of the protrusion (second protrusion) provided in the protrusion forming region 22, more preferably about 1 / 3 or less, and even more preferably about 1 / 5 or less.

[0186] like Figure 33 As shown, in the anvil 20, instead of the flat region 21 which is the first region, a region is provided where a third protrusion is formed, but the formation density of this protrusion (the proportion of area occupied by protrusions per unit area) is lower than the formation density of the protrusions in the protrusion forming region 22 (the second region). This region, like the flat region 21, corresponds to the first region of the anvil 20. Figure 33 In the example, a recess 2203A (third recess) is formed as an indentation of the anvil 20 in the portion of the outer surface (second outer surface) of the negative electrode tab assembly 220 that abuts against the first region of the anvil 20. The number of recesses 2203A formed in region 2203 is less or the opening area is smaller than that of recesses 2204A formed around region 2203. Therefore, it is possible to suppress the generation of large gaps between the outer surface of the negative electrode tab assembly 220 and the current collector 410, and to stably connect the negative electrode tab assembly 220 and the current collector 410.

[0187] In particular, in the anvil 20, the value of (total area of ​​the third protrusion formed in the first region when viewed from above / area of ​​the first region when viewed from above) / (total area of ​​the second protrusion formed in the second region when viewed from above / area of ​​the second region when viewed from above) is preferably about 1 / 2 or less, more preferably about 1 / 3 or less, and even more preferably about 1 / 5 or less.

[0188] (Modified example)

[0189] For example, in Figure 34 In a modified example, two protrusion forming regions 22, extending substantially parallel to the linear protrusion 11, are formed on both sides of the flat region 21. Figure 34 In the variations, the examples above ( Figure 26Compared to the previous method, since the range of the protrusion forming region 22 is limited, foil damage to the negative electrode tab 230 can be suppressed more effectively. At this time, since the protrusion forming region 22 extends in a direction approximately orthogonal to the vibration direction of the welding head 10, and the protrusion forming region 22 is formed on both sides of the linear protrusion 11 in the vibration direction of the welding head 10, foil misalignment of the negative electrode tabs 230 during ultrasonic vibration of the welding head 10 can be effectively suppressed.

[0190] It is preferable to form multiple linear protrusion forming regions 22. When forming multiple linear protrusion forming regions 22, it is preferable that they are formed approximately parallel to each other.

[0191] exist Figure 34 In the example, the preferred protrusion forming region 22 has a diameter of 60 mm. 2 The area to the left and right below (S22). Furthermore, in the protrusion forming area 22, the protrusions of the anvil 20 can be 110 per 10mm. 2 The density is around 10mm. 2 (More than 110 protrusions are set in the area.)

[0192] In addition, Figure 35 In a modified example, four protrusions are provided at the four corners of the flat region 21 to form regions 22. Figure 35 In the variant examples, with Figure 34 Compared to the previous example, by further defining the range of the protrusion formation region 22, foil breakage of the negative electrode tab 230 can be suppressed to the greatest extent.

[0193] exist Figure 34 as well as Figure 35 In the modified example shown, the anvil 20 also has a flat region 21 (first region) opposite to the protrusion 11 and a protrusion forming region 22 (second region) provided around the flat region 21. As in the example above, laser welding can be performed with the current collector 410 superimposed on the region 2203 of the negative electrode tab assembly 220.

[0194] In the above example, for ease of explanation, the connection between the negative electrode tab group 220 and the current collector 410 was described. 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 connected to the current collector 410 after being overlapped on the current collector 410. Furthermore, the connection of the positive electrode tab groups 250 and 280 is the same as that of the negative electrode tab groups 220 and 270.

[0195] In the above example, the method of connecting the negative electrode tab group 220 to the current collector 410 and then connecting the current collector 410 to the current collector 430 mounted on the sealing plate 120 was illustrated. However, the negative electrode tab group 220 can also be directly connected to the current collector 430 mounted on the sealing plate 120 (omitting the current collector 410). Therefore, since the current collector 410 can be omitted, a reduction in internal resistance or a higher energy density can be achieved. In this case, it is preferable to bend the negative electrode tab group 220 and the negative electrode tab group 270 respectively after connecting them to the current collector 430 mounted on the sealing plate 120 so that the first electrode body 201 overlaps with the second electrode body 202. This enables a higher energy density.

[0196] Negative electrode tab 230 and positive electrode tab 260 are preferably metal foils. Negative electrode tab 230 is preferably made of copper foil or copper alloy foil. Positive electrode tab 260 is preferably made of aluminum foil or aluminum alloy foil.

[0197] The thickness of each of the negative electrode tab 230 and the positive electrode tab 260 is preferably 3 μm or more, more preferably 5 μm or more. The thickness of each of the negative electrode tab 230 and the positive electrode tab 260 is preferably 50 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less.

[0198] The electrode tabs and current collectors that are joined together are preferably made of the same material. When the negative electrode tab 230 is made of copper or a copper alloy, the current collector 410 joined to the negative electrode tab 230 is also preferably made of copper or a copper alloy. When the positive electrode tab 260 is made of aluminum or an aluminum alloy, the current collector 420 joined to the positive electrode tab is also preferably made of aluminum or an aluminum alloy.

[0199] In the above embodiments, an example is shown in which a first region (flat region 21, etc.) and a second region (protrusion forming region 22) are provided in the anvil 20, but the scope of the technology is not limited to this. The first region and the second region may also be provided in the welding head 10, and the first protrusion may be provided in the anvil 20.

[0200] While embodiments of the present invention have been described, they should be considered illustrative rather than restrictive in all respects. The scope of the invention is defined by the technical solutions and is intended to include all equivalents and modifications within that scope.

Claims

1. A method for manufacturing an energy storage device, the energy storage device comprising an electrode body including a first electrode and a second electrode, the electrode body having a first electrode tab group formed by stacking multiple first electrode tabs connected to the first electrode, the first electrode tab group comprising a first outer surface and a second outer surface located on opposite sides of each other, the method for manufacturing the energy storage device being characterized in that it comprises: The process of manufacturing an electrode body having the first electrode tab assembly; and The process of forming a joint where the first electrode tabs in the first electrode tab group are joined together by applying vibration to the first electrode tab group using the welding head in the stacking direction of the first electrode tabs, with the first electrode tab group being clamped by the welding head and the anvil. One of the welding head and the anvil has a first protrusion on the surface that abuts against the first outer surface of the first electrode tab assembly. The welding head and the anvil each have a first region and a second region on the surface abutting against the second outer surface of the first electrode tab assembly. 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, 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 the ratio of the total area of ​​the third protrusion in top view to the area of ​​the first region in top view is less than the ratio of the total area of ​​the second protrusion in top view to the area of ​​the second region in top view. During the process of forming the joint, the vibration is applied in a state where the first protrusion is opposite to the first region across the first electrode tab group, the first protrusion abuts against the first outer surface of the first electrode tab group, and the first region and the plurality of second protrusions abut against the second outer surface of the first electrode tab group.

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

3. The method for manufacturing the energy storage device according to claim 1 or 2, characterized in that, The second region is formed in a manner that surrounds the first region.

4. The method for manufacturing the energy storage device according to claim 3, characterized in that, The second region is formed in a ring shape.

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

6. The method for manufacturing the energy storage device according to claim 1 or 2, characterized in that, The first protrusion includes a plurality of linear protrusions extending in substantially the same direction to each other.

7. The method for manufacturing the energy storage device according to claim 1 or 2, characterized in that, The joint includes a first joint region formed in the area abutted by the first protrusion and a second joint region formed around the first joint region.

8. The method for manufacturing the energy storage device according to claim 1 or 2, characterized in that, It also includes a step of joining the first electrode tab assembly to the first conductive component after the step of forming the joint.

9. The method for manufacturing an energy storage device according to claim 8, characterized in that, The junction in the first electrode tab group is joined to the first conductive component by irradiating an energy line from the first outer surface side toward the junction while the first conductive component is in contact with the second outer surface of the first electrode tab group.

10. An energy storage device, characterized in that, The energy storage device includes: The electrode body includes a first electrode and a second electrode; and The first conductive component is electrically connected to the electrode body. The electrode body includes a first electrode tab group formed by stacking multiple first electrode tabs connected to the first electrode. The first electrode tab assembly 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 being formed around the first region, and a plurality of second recesses being 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 shallower than the depth of the second recess, or a third recess is formed in the first region and the ratio of the total area of ​​the third recess in top view to the area of ​​the first region in top view is smaller than the ratio of the total area of ​​the second recess in top view to the area of ​​the second region in top view. When the first electrode tab assembly is viewed from the stacking direction of the first electrode tab, the first recess is positioned to overlap with the first region.

11. The energy storage device according to claim 10, characterized in that, The first region is a flat region.

12. The energy storage device according to claim 10 or 11, characterized in that, The first conductive component is bonded to the first region of the second outer surface.

13. The energy storage device according to claim 10 or 11, characterized in that, The second region is formed in a manner that surrounds the first region.

14. The energy storage device according to claim 13, characterized in that, The second region is formed in a ring shape.

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

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