Secondary battery

Abstract

To provide a secondary battery that enables improved permeability of an electrolyte into an electrode body.SOLUTION: A secondary battery includes an insulating sheet 700 covering an electrode body. The electrode body has a first surface. The insulating sheet 700 has a first region R1 formed near one end and a second region R2 formed near the other end. The first region R1 and the second region R2 cover the first surface. An overlapping region OR is provided in which the second region R2 overlaps the first region R1. In a width direction of the electrode body, the overlapping region OR includes a central region CR and end regions PR located on both sides of the central region CR, and the central region CR has recesses 710s as non-overlapping regions that reduce the overlapping area of the overlapping region OR.SELECTED DRAWING: Figure 28

Description

[Technical Field]

[0001] The present technology relates to a secondary battery. [Background technology]

[0002] Japanese Patent No. 4537353 (Patent Document 1) discloses a prismatic battery in which a positive electrode terminal is provided on one side of the battery case and a negative electrode terminal is provided on the other end. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4537353 Summary of the Invention [Problem to be solved by the invention]

[0004] By using a rectangular battery with the positive terminal on one side of the battery case and the negative terminal on the other end, it is easy to create a low-profile battery pack. However, there is room for further improvement in order to produce batteries that can be manufactured efficiently and stably. For example, it takes a long time or multiple injections to allow the electrolyte to penetrate into a high-capacity, high-density electrode body.

[0005] An object of the present technology is to provide a secondary battery that enables improved permeability of an electrolyte solution into an electrode assembly. [Means for solving the problem]

[0006] The present technology provides the following secondary battery and method for manufacturing the same. [1] An electrode assembly including a first electrode and a second electrode having a polarity different from that of the first electrode; a battery case accommodating the electrode assembly; a first electrode tab group electrically connected to the first electrode and arranged at one end of the electrode assembly; a second electrode tab group electrically connected to the second electrode and arranged at the other end of the electrode assembly; and an insulating sheet covering the electrode assembly, wherein the electrode assembly includes a first surface, and the insulating sheet includes a first region configured near one end and a second region configured near the other end, the first region and the second region covering the first surface, and an overlapping region where the second region overlaps the first region is provided; A secondary battery in which, in the width direction of the electrode body, the overlapping region includes a central region and end regions located on both sides of the central region, and the central region has a non-overlapping region that reduces the overlapping area of ​​the overlapping region.

[0007] [2] The secondary battery according to [1], wherein the ratio of the non-overlapping area in the central region to the overlapping area in the case where the non-overlapping area is not provided is 20% or more.

[0008] [3] A secondary battery according to [1] or [2], wherein at least one of the first region and the second region has, as the non-overlapping region, a recess in the circumferential edge of the central region that is recessed inward from the edge of the end region.

[0009] [4] The secondary battery according to [3], wherein the recess is provided in the second region. [5] The secondary battery according to [3] or [4], wherein the angle formed between the side edges at both ends of the recess and the edge of the end region is 100 degrees or more.

[0010] [6] The secondary battery described in any one of [1] to [5], further including a first spacer arranged on the end surface of the electrode body on which the first electrode tab group is provided, and a second spacer arranged on the end surface of the electrode body on which the second electrode tab group is provided, wherein the insulating sheet and the first spacer are connected on the side on which the first electrode tab group is provided, and the insulating sheet and the second spacer are connected on the side on which the second electrode tab group is provided.

[0011] [7] The secondary battery according to [6], wherein, in the area when viewed from the first surface side of the electrode body, when the ratio of [area of ​​the area where the first spacer, the first region, and the second region overlap] / [area of ​​the first spacer] is X1 and the ratio of [area of ​​the area where the electrode body, the first region, and the second region overlap] / [area of ​​the electrode body] is Y1, X1 is larger than Y1.

[0012] [8] A secondary battery according to [6] or [7], wherein the first region has an opening or a notch for connecting the insulating sheet to the first spacer, and the second region is connected to the first spacer in a region facing the opening or the notch.

[0013] [9] A secondary battery according to any one of [1] to [8], wherein, in the area when viewed from the side of the first surface of the electrode body, when the ratio of [area of ​​the overlapping portion between the first region and the second region in the edge region] to [area of ​​the edge region] is X2 and the ratio of [area of ​​the overlapping portion between the first region and the second region in the central region] to [area of ​​the central region] is Y2, X2 is larger than Y2.

[0014]

[10] A secondary battery described in any one of [1] to [9], wherein the electrode body has a third surface adjacent to the first surface, the insulating sheet has a fourth region covering the third surface, a folded portion is provided between the first region and the fourth region, and an end of the second region is located away from the folded portion.

[0015]

[11] The secondary battery according to any one of [1] to

[10] , wherein the battery case is provided with a gas release valve, and the surface of the battery case on which the gas release valve is provided faces the first surface.

[0016]

[12] The secondary battery according to any one of [1] to

[11] , wherein the battery case includes a case body having a first opening at one end and a second opening at the other end, a first sealing plate that seals the first opening and is welded to the case body, and a second sealing plate that seals the second opening and is welded to the case body, wherein the first electrode tab group is arranged at the end of the electrode body on the first opening side, and the second electrode tab group is arranged at the end of the electrode body on the second opening side. [Effects of the Invention]

[0017] According to the present technology, it is possible to provide a secondary battery in which the permeability of the electrolyte into the electrode body is improved. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a front view showing the configuration of a secondary battery according to Embodiment 1. FIG. [Figure 2] 2 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow II. [Figure 3] 3 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow III. [Figure 4] 4 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow IV. FIG. [Figure 5] 2 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow V. FIG. [Figure 6] FIG. 2 is a front cross-sectional view of the secondary battery shown in FIG. [Figure 7] FIG. [Figure 8] FIG. [Figure 9] FIG. [Figure 10] FIG. [Figure 11] 1. FIG. 1 is a cross-sectional view of the secondary battery taken along the line XI-XI in FIG. [Figure 12] 1. FIG. 2 is a cross-sectional view of the secondary battery shown in FIG. [Figure 13] 1 is a flowchart showing a method for manufacturing a secondary battery according to one embodiment. [Figure 14] 1 is a perspective view showing a state before two electrode bodies included in a secondary battery according to one embodiment are overlapped. [Figure 15] 15 is a cross-sectional view of the electrode body and current collector shown in FIG. 14 taken along the line XV-XV. [Figure 16] FIG. 2 is a perspective view showing a state in which a holder and a spacer are attached to an electrode body. [Figure 17] FIG. 2 is a perspective view showing a state in which a sealing plate is attached to a negative electrode-side current collector. [Figure 18] 18 is a cross-sectional view taken along the line XVIII-XVIII of the electrode body and current collector shown in FIG. 17. [Figure 19] FIG. 1 is a first perspective view showing the configuration of a spacer. [Figure 20] FIG. 2 is a second perspective view showing the configuration of the spacer. [Figure 21] FIG. 10 is a side view showing the positional relationship between a spacer and an insulating sheet. [Figure 22] FIG. 2 is a perspective view showing a state in which an electrode body is being inserted into a case main body. [Figure 23] FIG. 2 is a perspective view showing a state in which a sealing plate is attached to a current collector on the positive electrode side. [Figure 24] 24 is a cross-sectional view of the electrode body and current collector shown in FIG. 23 taken along the line XXIV-XXIV. [Figure 25] FIG. 2 is a perspective view showing the configuration of a secondary battery. [Figure 26] 26 is a cross-sectional view of the secondary battery shown in FIG. 25 taken along the line XXVI-XXVI. [Figure 27] 26 is a cross-sectional view taken along the line XXVII-XXVII of the secondary battery shown in FIG. 25. [Figure 28] FIG. [Figure 29]26 is a reference cross-sectional view corresponding to the cross section XXVI-XXVI of the secondary battery shown in FIG. 25. FIG. [Figure 30] 26 is a reference cross-sectional view corresponding to the cross section XXVI-XXVI of the secondary battery shown in FIG. 25. FIG. [Figure 31] FIG. 4 is a diagram showing the area of ​​each region when viewed from the first surface side of the electrode body. [Figure 32] FIG. 3 is a diagram showing the central region and end region when viewed from the first surface side of the electrode body. [Figure 33] 31 is a partial enlarged view of the first surface side of the electrode body shown in FIG. 30. FIG. [Figure 34] FIG. 10 is a development view of an insulating sheet according to a second embodiment. [Figure 35] FIG. 10 is a development view of an insulating sheet according to a third embodiment. [Figure 36] FIG. 10 is a development view of an insulating sheet according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] Hereinafter, embodiments of the present technology will be described. Note that the same or corresponding parts are denoted by the same reference characters, and description thereof may not be repeated.

[0020] In the embodiments described below, when numbers, amounts, etc. are mentioned, the scope of the present technology is not necessarily limited to those numbers, amounts, etc., unless otherwise specified. Furthermore, in the following embodiments, each component is not necessarily essential to the present technology, unless otherwise specified. Furthermore, the present technology is not necessarily limited to those that achieve all of the effects mentioned in the present embodiments.

[0021] In this specification, the words "comprise," "include," and "have" are open-ended, meaning that when a certain feature is included, other features may or may not be included.

[0022] When geometric terms and terms expressing positional and directional relationships, such as "parallel," "orthogonal," "45° diagonal," "coaxial," and "along" are used in this specification, these terms allow for manufacturing errors and slight variations. When terms expressing relative positional relationships, such as "upper side" and "lower side," are used in this specification, these terms are used to indicate relative positional relationships in a single state, and the relative positional relationships can be reversed or rotated to any angle depending on the installation direction of each mechanism (for example, by turning the entire mechanism upside down).

[0023] In this specification, the term "secondary battery" is not limited to lithium ion batteries, but may include other secondary batteries such as nickel-metal hydride batteries and sodium ion batteries. In this specification, the term "electrode" may collectively refer to a positive electrode and a negative electrode.

[0024] In the drawings, if the electrode body of the secondary battery is a laminated electrode body, the longitudinal direction of the laminated surface is the X direction, and if the electrode body is a wound electrode body, the direction along the winding axis is the X direction. The shorter side direction of the electrode body as viewed from the X direction is the Y direction, and the longer side direction of the electrode body as viewed from the X direction is the Z direction. To facilitate understanding of the invention, the dimensions of each component in the drawings may be slightly different from the actual dimensions.

[0025] In this specification, the first direction (X direction) may be referred to as the "width direction" of the secondary battery, electrode body, and case body, the second direction (Z direction) may be referred to as the "height direction" of the secondary battery or case body, and the third direction (Y direction) may be referred to as the "thickness direction" of the secondary battery or case body.

[0026] (Embodiment 1: Overall Configuration of Battery) Fig. 1 is a front view of a secondary battery 1 according to embodiment 1. Figs. 2 to 5 are diagrams showing the secondary battery 1 shown in Fig. 1 as viewed from the directions of arrows II, III, IV, and V, respectively. Fig. 6 is a front cross-sectional view of the secondary battery 1 shown in Fig. 1.

[0027] The secondary battery 1 can be mounted in an electric vehicle (BEV: Battery Electric Vehicle), a plug-in hybrid electric vehicle (PHEV: Plug-in Hybrid Electric Vehicle), a hybrid electric vehicle (HEV: Hybrid Electric Vehicle), etc. However, the use of the secondary battery 1 is not limited to being mounted in a vehicle.

[0028] 1 to 6, the secondary battery 1 includes a case 100, an electrode assembly 200, an electrode terminal 300, and a current collector 400. The case 100 includes a case body 110, a sealing plate 120 (first sealing plate), and a sealing plate 130 (second sealing plate).

[0029] When configuring a battery pack including secondary batteries 1, multiple secondary batteries 1 are stacked in their thickness direction. The stacked secondary batteries 1 may be constrained in the stacking direction (Y direction) by a constraining member to form a battery module, or the battery pack may be directly supported on the side surface of a battery pack case without using a constraining member.

[0030] The case body 110 is made 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, an aluminum alloy, iron, an iron alloy, or the like.

[0031] As shown in Figures 1 and 2, a sealing plate 120 (first wall) and a sealing plate 130 (second wall) are provided at both ends of the case body. The case body 110 can be formed into a rectangular tube shape, for example, by abutting the edges of bent plate-like members (at joint 115 shown in Figure 2) and joining them together (for example, by laser welding). The corners of the "rectangular tube" may be rounded. Furthermore, the secondary battery in the present technology is not necessarily limited to a rectangular secondary battery.

[0032] In this embodiment, the case body 110 is formed so that it is 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 allows for the construction of 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 allows for the construction of a relatively low-height secondary battery 1, which improves, for example, the mountability in a vehicle.

[0033] The case main body 110 includes a pair of first side surface portions 111 and a pair of second side surface portions 112. The pair of first side surface portions 111 constitute part of the side surfaces of the case 100. The pair of second side surface portions 112 constitute the bottom surface portion and the top surface portion of the case 100. The pair of first side surface portions 111 and the pair of second side surface portions 112 are arranged to intersect with each other. The pair of first side surface portions 111 and the pair of second side surface portions 112 are connected at their respective ends. It is desirable that each of the pair of first side surface portions 111 has a larger area than each of the pair of second side surface portions 112.

[0034] 5, a gas release valve 150 is provided on one second side surface portion 112A of the pair of second side surface portions 112. The gas release valve 150 extends in the width direction (X direction) of the secondary battery 1. The gas release valve 150 extends in the X direction from the center of the case body 110 in the X direction but does not reach both ends. The shape of the gas release valve 150 can be changed as appropriate.

[0035] The thickness of the plate-like member in the gas release valve 150 is thinner than the thickness of the plate-like members of the case body 110 other than the gas release valve 150. As a result, when the pressure inside the case 100 reaches or exceeds a predetermined value, the gas release valve 150 breaks preferentially compared to other parts of the case body 110, and releases gas inside the case 100 to the outside.

[0036] 2, a joint 115 is formed on the other second side surface portion 112B of the pair of second side surface portions 112. The joint 115 extends in the width direction (X direction) of the secondary battery 1. At the joint 115, the edges of the plate-like members that make up the case body 110 are joined together.

[0037] As shown in Fig. 3, an opening 113 (first opening) is provided at an end of a first side in a first direction (X direction) of case body 110. Opening 113 is sealed by sealing plate 120. A joint 115 is formed in opening 113 to seal opening 113. Opening 113 and sealing plate 120 have a generally rectangular shape with the Y direction as the short side direction and the Z direction as the long side direction. The generally rectangular shape includes a rectangular shape or a substantially rectangular shape such as a rectangular shape with rounded corners.

[0038] A negative electrode terminal 301 is provided on the sealing plate 120 (first sealing plate). The position of the negative electrode terminal 301 can be changed as appropriate.

[0039] 4, an opening 114 (second opening) is provided at an end of a second side of case body 110 opposite the first side in the first direction (X direction). That is, opening 114 is located at an end opposite opening 113, and openings 113 and 114 face each other. Opening 114 is sealed by sealing plate 130. A joint 115 is formed in opening 114 to seal opening 114. Opening 114 and sealing plate 130 have a substantially rectangular shape with the Y direction as the short side direction and the Z direction as the long side direction.

[0040] A positive electrode terminal 302 and a liquid injection hole 134 are provided on the sealing plate 130 (second sealing plate). The positions of the positive electrode terminal 302 and the liquid injection hole 134 can be changed as appropriate.

[0041] The sealing plates 120 and 130 are made of metal. Specifically, the sealing plates 120 and 130 are made of aluminum, an aluminum alloy, iron, an iron alloy, or the like.

[0042] The negative electrode terminal 301 (first electrode terminal) is electrically connected to the negative electrode of the electrode body 200. The negative electrode terminal 301 is attached to the sealing plate 120, that is, the case 100.

[0043] The positive electrode terminal 302 (second electrode terminal) is electrically connected to the positive electrode of the electrode body 200. The positive electrode terminal 302 is attached to the sealing plate 130, that is, the case 100.

[0044] The negative electrode terminal 301 is made of a conductive material (more specifically, a metal), and may be made of, for example, copper or a copper alloy. The outer surface of the negative electrode terminal 301 may be provided with a portion or layer made of aluminum or an aluminum alloy.

[0045] The positive terminal 302 is made of a conductive material (more specifically, a metal), and may be made of, for example, aluminum or an aluminum alloy.

[0046] The liquid inlet hole 134 is sealed with a sealing member (not shown), which may be, for example, a blind rivet or other metal member.

[0047] The electrode assembly 200 is a flat electrode assembly in which positive and negative electrode plates, described below, are stacked. Specifically, the electrode assembly 200 is a laminated electrode assembly in which multiple positive and negative electrode plates are alternately stacked with a separator 800, described below, interposed therebetween. However, in this specification, the term "electrode assembly" is not limited to a laminated electrode assembly, but may also refer to a wound electrode assembly in which strip-shaped positive and negative electrode plates are wound together with a strip-shaped separator interposed therebetween. The separator may be formed, for example, of a polyolefin microporous membrane. When the electrode assembly is a laminated electrode assembly including multiple positive and negative electrode plates, the positive electrode tabs provided on each positive electrode plate may be stacked to form a positive electrode tab group, and the negative electrode tabs provided on each negative electrode plate may be stacked to form a negative electrode tab group.

[0048] As shown in Fig. 6, the case 100 houses the electrode assembly 200. Fig. 6 illustrates a first electrode assembly 201, which will be described later. The first electrode assembly 201 is housed in the case 100 so that its longitudinal direction is parallel to the X direction.

[0049] Specifically, one or more laminated electrode bodies are housed together with an electrolytic solution (electrolyte), not shown, inside an insulating sheet 700 (described below) placed inside the case 100. The electrolytic solution (nonaqueous electrolytic solution) can be, for example, a nonaqueous solvent made 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 LiPF is dissolved at a concentration of 1.2 mol / L. A solid electrolyte may be used instead of the electrolytic solution.

[0050] The first electrode body 201 includes a substantially rectangular main body portion, a negative electrode tab group 220 (first electrode tab group), and a positive electrode tab group 250 (second electrode tab group).

[0051] 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 the end of a first side of the first electrode body 201 in a first direction (X direction) relative to the main body. In this embodiment, the first side is the sealing plate 120 side. The positive electrode tab group 250 is located at the end of a second side of the first electrode body 201 in the first direction (X direction) relative to the main body. In this embodiment, the second side is the sealing plate 130 side.

[0052] The negative electrode tab group 220 and the positive electrode tab group 250 are formed so as to protrude from the center portion of the electrode body 200 toward the sealing plate 120 or the sealing plate 130, respectively.

[0053] The current collectors 400 include 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 a plate-shaped member. The electrode assembly 200 is electrically connected to a negative electrode terminal 301 and a positive electrode terminal 302 via the current collectors 400.

[0054] The negative electrode current collector 400A is disposed 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), and may be made of, for example, copper or a copper alloy. Details of the negative electrode current collector 400A will be described later.

[0055] The positive electrode current collector 400B is disposed 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), and may be made of, for example, 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 serve as the positive electrode terminal 302. Details of the positive electrode current collector 400B will be described later.

[0056] (Configuration of electrode body 200) 7 is a cross-sectional view of the negative electrode plate 210 (a cross-sectional view taken along line VII-VII in FIG. 8), and FIG. 8 is a front view showing the negative electrode plate 210. As shown in FIG.

[0057] As shown in FIG. 8, a plurality of negative electrode tabs 230 (first electrode tabs) made of negative electrode cores 211 are provided at one end in the width direction of the negative electrode plate 210. When the negative electrode plates 210 are stacked, the plurality of negative electrode tabs 230 are stacked to form a negative electrode tab group 220. The length in the protruding direction of each of the negative electrode tabs 230 of the plurality of negative electrode plates 210 is adjusted as appropriate, taking into consideration 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 tabs 230 is not limited to the example shown in FIG. 7.

[0058] FIG. 9 is a cross-sectional view of the positive electrode plate 240 (cross-sectional view taken along line IX-IX in FIG. 10), and FIG. 10 is a front view showing the positive electrode plate 240. As shown in FIG.

[0059] As shown in Fig. 10, a plurality of positive electrode tabs 260 (second electrode tabs) made of positive electrode cores 241 are provided at one end in the width direction of the molded positive electrode plate 240. When the positive electrode plates 240 are stacked, the plurality of positive electrode tabs 260 are stacked to form a positive electrode tab group 250. The length in the protruding direction of each of the positive electrode tabs 260 of the plurality of positive electrode plates 240 is adjusted as appropriate, taking into consideration 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 the example shown in Fig. 10.

[0060] A positive electrode protective layer 243 is provided at the base of the positive electrode tab 260. The positive electrode protective layer 243 does not necessarily have to be provided at the base of the positive electrode tab 260.

[0061] In a typical example, the thickness of the negative electrode tab 230 (one piece) is smaller than the thickness of the positive electrode tab 260 (one piece). In this case, the thickness of the negative electrode tab group 220 is smaller than the thickness of the positive electrode tab group 250.

[0062] (Connection structure between electrode body 200 and current collector 400) Fig. 11 is a cross-sectional view taken along line XI-XI of the secondary battery shown in Fig. 1. As shown in Fig. 11, 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 (second electrode) and a negative electrode (first electrode). The electrode body 200 may be composed of three or more electrode bodies.

[0063] 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.

[0064] The first electrode body 201 includes a negative electrode tab group 220. The negative electrode tab group 220 is electrically connected to one current collector 410 (negative electrode current collector) at a first end 205 in the X direction. The second electrode body 202 includes a negative electrode tab group 270. The negative electrode tab group 270 is electrically connected to another current collector 410 (negative electrode current collector) at a third end 207 in the X direction.

[0065] The negative electrode tab group 220 has a curved portion 221 and a tip portion 222. The curved portion 221 is a portion of the negative electrode tab group 220 that is curved on the side where the first electrode is connected, relative to the tip portion 222. The tip portion 222 is a portion of the negative electrode tab group 220 that is located at the end opposite the side where the first electrode is connected.

[0066] The negative electrode tab group 270 has a curved portion 271 and a tip portion 272. The curved portion 271 is a portion of the negative electrode tab group 270 that is curved on the side where the first electrode is connected, relative to the tip portion 272. The tip portion 272 is a portion of the negative electrode tab group 270 that is located at the end opposite the side where the first electrode is connected.

[0067] The negative electrode tab group 220 and the negative electrode tab group 270 are curved in opposite directions so that the tip portions 222, 272 approach each other. In the present embodiment, the tip portions 222, 272 are spaced apart, but this configuration is not limiting, and the tip portions 222, 272 may be in contact with each other.

[0068] 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. The negative electrode current collector 400A in this embodiment is connected to the negative electrode terminal 301 between the electrode body 200 and the sealing plate 120.

[0069] The negative electrode current collector 400A includes two current collectors, a current collector 410 and a current collector 430. Current collector 410 is a plate-like member. Current collector 410 has its longitudinal direction in the Z direction and its transverse direction in the Y direction. Current collector 430 is a plate-like member. Current collector 430 has its longitudinal direction in the Z direction and its transverse direction in the Y direction. Current collector 410 and current collector 430 are arranged in parallel in the X direction. In this way, current collector 410 and current collector 430 are composed of separate parts.

[0070] The negative electrode tab group 220 is joined to one current collector 410 at a joining point 411, which will be described later (see FIG. 14). The negative electrode tab group 270 is joined to another current collector 410 at a joining point 411, which will be described later (see FIG. 14). The joining points 411 can be formed by, for example, ultrasonic welding, resistance welding, laser welding, caulking, or the like. In this embodiment, the negative electrode tab group 220 and one current collector 410, and the negative electrode tab group 270 and another current collector 410 are joined by, for example, ultrasonic welding.

[0071] The current collector 430 is joined to one current collector 410 and another current collector 410 at joints (not shown) located at the ends in the Z direction. The current collector 430 is connected to the negative electrode terminal 301. The connection between the current collector 430 and the negative electrode terminal 301 can be formed by, for example, crimping and / or welding.

[0072] Negative electrode terminal 301 is exposed to the outside of sealing plate 120. Negative electrode terminal 301 is connected to plate-shaped member 303. Negative electrode terminal 301 preferably includes region 301a made of copper or a copper alloy and region 301b made of aluminum or an aluminum alloy, and region 301a made of copper or a copper alloy is preferably connected to current collector 430.

[0073] The plate-shaped member 303 is located outside the sealing plate 120. The plate-shaped member 303 is arranged so as to fit along the sealing plate 120. The plate-shaped member 303 is conductive. The plate-shaped member 303 is arranged to ensure a connection area with a bus bar or the like that electrically connects the secondary battery 1 to another adjacent secondary battery. The connection between the negative electrode terminal 301 and the plate-shaped member 303 can be formed by, for example, laser welding.

[0074] An insulating member 510 is disposed between the plate-shaped member 303 and the sealing plate 120. An insulating member 520 is disposed between the negative electrode terminal 301 and the sealing plate 120. An insulating member 530 is disposed between the current collector 430 and the sealing plate 120.

[0075] However, the negative electrode terminal 301 may be electrically connected to the sealing plate 120. Alternatively, the sealing plate 120 may serve as the negative electrode terminal 301.

[0076] A spacer 600 (first spacer), which will be described later, is disposed between the sealing plate 120 and the main body of the electrode body 200 (excluding the negative electrode tab group 220). The spacer 600 is made of an insulating resin material. The negative electrode tab group 220 passes through the interior of the spacer 600, and is thereby protected by the spacer 600. Note that it is also possible to employ a configuration in which the spacer 600 (first spacer) is not provided.

[0077] The detailed structure of the spacer 600 will be described later, but the spacer 600 has a protrusion 616 that protrudes in the Y direction. The protrusion 616 of the spacer 600 plays the role of a guide to make it easier for the bending portions 221, 271 to bend when the bending portions 221, 271 are bent.

[0078] A resin insulating sheet 700 (electrode body holder) is disposed between the electrode body 200 and the case body 110. The insulating sheet 700 may be made of, for example, resin. More specifically, the material of the insulating sheet 700 is, for example, polypropylene (PP), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyimide (PI), or polyolefin (PO).

[0079] Fig. 12 is a cross-sectional view taken along the line XII-XII of the secondary battery shown in Fig. 1. The connection structure between the electrode body 200 and the current collector 400 on the positive electrode side of the secondary battery 1 in this embodiment differs from the structure on the negative electrode side in that one current collector 410 and a portion corresponding to the other current collector 410 on the negative electrode side are formed from a single component.

[0080] The first electrode body 201 includes a positive electrode tab group 250. The positive electrode tab group 250 is electrically connected to a current collector 420 (positive electrode current collector) at a second end 206 in the X direction. The second electrode body 202 includes a positive electrode tab group 280. The positive electrode tab group 280 is electrically connected to the current collector 420 (positive electrode current collector) at a fourth end 208 in the X direction.

[0081] The positive electrode tab group 250 has a curved portion 251 and a tip portion 252. The curved portion 251 is a portion of the positive electrode tab group 250 that is curved on the side where the second electrode is connected, relative to the tip portion 252. The tip portion 252 is a portion of the positive electrode tab group 250 that is located at the end opposite the side where the second electrode is connected.

[0082] The positive electrode tab group 280 has a curved portion 281 and a tip portion 282. The curved portion 281 is a portion of the positive electrode tab group 280 that is curved on the side where the second electrode is connected, relative to the tip portion 282. The tip portion 282 is a portion of the positive electrode tab group 280 that is located at the end opposite the side where the second electrode is connected.

[0083] The positive electrode tab group 250 and the positive electrode tab group 280 are curved in opposite directions so that the tip portions 252, 282 approach each other. In the present embodiment, the tip portions 252, 272 are spaced apart, but this configuration is not limiting, and the tip portions 252, 282 may be in contact with each other.

[0084] 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. The positive electrode current collector 400B in this embodiment is connected to the positive electrode terminal 302 between the electrode body 200 and the sealing plate 130.

[0085] Positive electrode current collector 400B includes current collector 420 (first current collecting member) and current collector 450 (second current collecting member). Plate 460 is interposed as an insulating member between current collector 420 (first current collecting member) and current collector 450 (second current collecting member), but they are electrically connected at a position different from the cross section shown in the drawing.

[0086] Current collector 420 is a plate-like member. Current collector 420 has a longitudinal direction in the Z direction and a lateral direction in the Y direction. Current collector 420 is made up of a single, integrated part.

[0087] The positive electrode tab group 250 and the positive electrode tab group 280 are joined to the current collector 420, which is configured as a single part, at joints 421 (see FIG. 14 ), which will be described later. The joints 421 can be formed by, for example, ultrasonic welding, resistance welding, laser welding, crimping, or the like. In this embodiment, the positive electrode tab group 250 and the positive electrode tab group 280 are joined to the current collector 420 by, for example, ultrasonic welding.

[0088] The current collector 440 is joined to the current collector 420 at a joint (not shown) located at an end in the Z direction. The current collector 440 is connected to the positive electrode terminal 302. The connection between the current collector 440 and the positive electrode terminal 302 can be formed by, for example, crimping and / or welding.

[0089] Positive electrode terminal 302 is exposed to the outside of sealing plate 130 and is provided so as to reach current collector 440 of positive electrode current collector 400B provided on the inside surface side of sealing plate 130. Positive electrode terminal 302 is connected to plate-shaped member 304.

[0090] The plate-shaped member 304 is located outside the sealing plate 130. The plate-shaped member 304 is arranged so as to fit along the sealing plate 130. The plate-shaped member 304 is conductive. The plate-shaped member 304 is arranged to ensure a connection area with a bus bar or the like that electrically connects the secondary battery 1 to another adjacent secondary battery. The connection between the positive electrode terminal 302 and the plate-shaped member 304 can be formed by, for example, laser welding.

[0091] An insulating member 510 is disposed between the plate-shaped member 304 and the sealing plate 130. An insulating member 520 is disposed between the positive electrode terminal 302 and the sealing plate 130. An insulating member 470 is disposed between the current collector 440 and the sealing plate 130.

[0092] However, the positive electrode terminal 302 may be electrically connected to the sealing plate 130. Alternatively, the sealing plate 130 may serve as the positive electrode terminal 302.

[0093] A spacer 600 (second spacer) is disposed between the sealing plate 130 and the main body of the electrode assembly 200 (excluding the positive electrode tab groups 250, 280). The spacer 600 is made of an insulating resin material. The positive electrode tab groups 250, 280 pass through the interior of the spacer 600, and are thereby protected by the spacer 600. Note that it is also possible to employ a configuration in which the spacer 600 (second spacer) is not provided.

[0094] The detailed structure of the spacer 600 will be described later, but the spacer 600 has a protrusion 616 that protrudes in the Y direction. The protrusion 616 of the spacer 600 plays the role of a guide to make it easier for the bending portions 251, 281 to bend when the bending portions 251, 281 are bent.

[0095] Between the electrode body 200 and the case body 110, the above-mentioned resin insulating sheet 700 (electrode body holder) is disposed.

[0096] (Manufacturing process of secondary battery 1) A method for manufacturing a secondary battery according to the present embodiment will be described below. Fig. 13 is a flowchart showing a method for manufacturing a secondary battery according to embodiment 1. Fig. 14 is a perspective view showing a state before two electrode bodies included in the secondary battery according to embodiment 1 are overlapped. Fig. 15 is a cross-sectional view taken along the line XV-XV of the electrode body and current collector shown in Fig. 14.

[0097] 13, in the method for manufacturing a secondary battery according to the present embodiment, first, a first electrode body 201 and a second electrode body 202 are fabricated (step S1). It is preferable that a portion of the tip of each of the negative electrode tab group 220, the positive electrode tab group 250, the negative electrode tab group 270, and the positive electrode tab group 280 is cut off so that the tip lengths are the same when bundled.

[0098] 13 to 15, after the first electrode body 201 and the second electrode body 202 are fabricated, the negative electrode tab group 220 is joined to one current collector 410 (step S2). The negative electrode tab group 220 is joined to the one current collector 410 at a joining portion 411. Next, the negative electrode tab group 270 is joined to another current collector 410 (step S3). The negative electrode tab group 270 is joined to the other current collector 410 at the joining portion 411.

[0099] Next, the first electrode body 201, the current collector 420, and the second electrode body 202 are arranged in this order in a first direction (DR1 direction). The positive electrode tab group 250 is arranged on one side of the current collector 420 in the first direction (DR1 direction). With the positive electrode tab group 280 arranged on the other side of the current collector 420 in the first direction (DR1 direction), the positive electrode tab group 250 and the positive electrode tab group 280 are joined to the current collector 420 (step S4). The positive electrode tab group 250 and the positive electrode tab group 280 are joined to the current collector 420 at joining locations 421.

[0100] In the height direction of the first electrode body 201 and the second electrode body 202, one current collector 410, the other current collector 410, and the current collector 420 are arranged biased to one side from the center of the first electrode body 201 and the second electrode body 202. This allows the current collectors to be configured to be short, and therefore the current collectors can be made compact.

[0101] The one current collector 410, the other current collector 410, and the current collector 420 are not limited to this configuration. The current collector 410 and the current collector 420 may be disposed at 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. In this case, the negative electrode tab group 220, the positive electrode tab group 250, the negative electrode tab group 270, and the positive electrode tab group 280 are each disposed at the center of the first electrode body 201 and the second electrode body 202 in line with the current collector 410 and the current collector 420 in the height direction of the first electrode body 201 and the second electrode body 202.

[0102] The order of the steps of joining the current collector 410 and the current collector 420 to the first electrode body 201 and the second electrode body 202, respectively, is not limited to the above, and the order may be changed. The step of joining the current collector 410 to the first electrode body 201 and the second electrode body 202, respectively, 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 420 to the first electrode body 201 and the second electrode body 202.

[0103] Next, after joining the positive electrode tab group 250 and the positive electrode tab group 280 to the current collector 420, the positive electrode tab group 250 and the positive electrode tab group 280 are folded in the thickness direction of the first electrode body 201 and the second electrode body 202 (the direction perpendicular to the DR1 direction in FIGS. 14 and 15 ) to overlap the first electrode body 201 and the second electrode body 202 (step S5). In other words, the first electrode body 201 and the second electrode body 202 are gathered together.

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

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

[0106] 13 and 16 are perspective views showing a state in which the holder and spacer are attached to the electrode assembly. As shown in Fig. 16, next, the spacer 600 and the insulating sheet 700 are assembled to the electrode assembly 200 (step S6).

[0107] The insulating sheet 700 does not necessarily have to cover the entire surface of the electrode assembly 200. The insulating sheet 700 preferably covers approximately 50% or more, and more preferably approximately 70% or more, of the area of ​​the outer surface of the electrode assembly. Of the six faces of the substantially rectangular parallelepiped (flat) electrode assembly 200, the insulating sheet 700 preferably covers the entire four faces other than at least the two faces on which the negative electrode tab group 220 and the positive electrode tab group 250 are formed. The specific form of the insulating sheet 700 will be described later.

[0108] Fig. 17 is a perspective view showing a state in which a sealing plate 120 is attached to the negative electrode current collector. Fig. 18 is a cross-sectional view taken along line XVIII-XVIII of the electrode assembly and current collector shown in Fig. 17. Figs. 19 and 20 are first and second perspective views showing the shape of a spacer 600, and Fig. 21 is a side view showing the positional relationship between the spacer 600 and an insulating sheet 700. Note that the case body 110 is omitted from Fig. 18.

[0109] 19 and 20, spacer 600 is made of an insulating resin member. Spacer 600 includes first component 612 and second component 614, each surrounded by side walls on three sides, and connecting wall 611 connecting one side wall of first component 612 and one side wall of second component 614. A protrusion 616 is provided on the inside of connecting wall 611 so as to extend between first component 612 and second component 614 (in the Z direction).

[0110] The first component 612 includes a first plate portion 617 provided to connect three walls. A plurality of elliptical first through holes 617s are provided in the first plate portion 617. The shape and number of the first through holes 617s may be selected appropriately and are not limited to the shape and number shown in the figure. A first protrusion 612p protruding outward is provided in a region of the first component 612 opposite the first plate portion 617 (the side opposite the electrode body).

[0111] The second component 614 includes a second plate portion 618 that is provided to connect three walls. The second plate portion 618 is provided with a plurality of elliptical second through-holes 618s. The shape and number of the second through-holes 618s may be selected appropriately and are not limited to the shape and number shown in the figure. A second protrusion 614p that protrudes outward is provided in a region of the second component 614 opposite the second plate portion 618 (the side opposite the electrode body).

[0112] The first plate portion 617 and the second plate portion 618 are located on the end face side of the electrode assembly. These plate portions may abut the end face of the electrode assembly. Even if they do not abut, the shortest distance to the electrode assembly is preferably within 2 mm, more preferably within 1 mm. Furthermore, by providing the first through-hole 617s and the second through-hole 618s, when the secondary battery 1 shown in FIG. 1 is placed with the Z direction facing upward (the openings 113 (first opening) and 114 (second opening) at both ends of the case body 110 are arranged on the left and right), even if the electrolyte is forced out of the electrode assembly during charging (when the electrode plates generally expand) and flows out of this portion, it is easily returned to the electrode assembly during discharging (when the electrode plates generally contract).

[0113] The outer dimensions of the spacers 600 (first spacer and second spacer) are preferably smaller than the outer dimensions of the electrode body 200. Since the electrode body 200 is wrapped in the insulating sheet 700 and the spacers 600 are also wrapped in the insulating sheet 700, making the outer dimensions of the spacers 600 smaller than the spacers 600 can improve the ease of insertion of the electrode body 200 into the case body 110.

[0114] As shown in FIG. 21 , when the electrode assembly 200 is covered with an insulating sheet 700, it is preferable that the spacer 600 is also covered with the insulating sheet 700. In this case, the negative electrode tab group and the positive electrode tab group pass through the interior of the spacer 600, and thus the spacer 600 protects the negative electrode tab group and the positive electrode tab group. Furthermore, by covering the spacer 600 with the insulating sheet 700, the negative electrode tab group and the positive electrode tab group are further protected. Note that it is preferable that the first protrusion 612p and the second protrusion 614p provided on the spacer 600 are exposed from the insulating sheet 700.

[0115] 13, 17, and 18, after the negative electrode tab group 220 is joined to the current collector 410, the negative electrode tab group 270 is joined to the current collector 430, and the first electrode body 201 and the second electrode body 202 are overlapped, one current collector 410 and the other current collector 410 are electrically connected to the negative electrode terminal 301 via the current collector 430 (step S7). Note that step S7 can also be performed before step S6.

[0116] Specifically, the negative electrode tab group 220 and the negative electrode tab group 270 are bent so that the leading ends 222, 272 face each other.

[0117] 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 one current collector 410 and the other current collector 410 in the X direction. Note that the connection of the plate-like member 303 to the negative electrode terminal 301 may be made at any time. The current collector 430, the one current collector 410, and the other current collector 410 are joined by laser welding between the sealing plate 120 and the insulating sheet 700.

[0118] Fig. 22 is a perspective view showing the state in which the electrode bodies are being inserted into the case body. Next, as shown in Fig. 13 and Fig. 22, after the first electrode body 201 and the second electrode body 202 are stacked on top of each other, the first electrode body 201 and the second electrode body 202 are inserted into the case body 110 through the opening 113, starting with the current collector 420 side (step S8). At this time, the first electrode body 201 and the second electrode body 202 are preferably inserted into the case body 110 in a state in which the negative electrode active material layer 212 at the ends of the first electrode body 201 and the second electrode body 202 on the negative electrode tab 230 side protrudes toward the negative electrode tab 230 beyond the end of the positive electrode active material layer 242.

[0119] The negative electrode tab group 220 and the negative electrode tab group 270 are curved by bringing the sealing plate 120 and the main body of the electrode body 200 (the first electrode body 201 and the second electrode body 202) closer to each other. Preferably, the sealing plate 120 and the main body of the electrode body 200 arranged in the case body 110 are brought closer to each other so that the sealing plate 120 and the case body 110 are brought closer to each other. As shown in FIG. 11 , the negative electrode tab group 220 and the negative electrode tab group 270 are curved along the shape of the spacer 600 so that the folded-back portions of the curved portions 221, 271 approach the case body 110 in the Y direction.

[0120] 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. By temporarily joining, the sealing plate 120 is partially joined to the opening 113 of the case body 110. As a result, the sealing plate 120 is positioned relative to the case body 110.

[0121] 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 may be pushed from the current collectors 410 and 430 sides. When the electrode body 200 is pushed from the current collectors 410 and 430 sides, the negative electrode tab group 220 and the negative electrode tab group 270 can be bent at the same time.

[0122] Referring to Fig. 23, this is a perspective view showing a state in which a sealing plate 130 is attached to the current collector on the positive electrode side. Fig. 24 is a cross-sectional view taken along line XXIII-XXIII of the electrode assembly and current collector shown in Fig. 23. In Fig. 24, the case body 110 is omitted.

[0123] As shown in FIGS. 13, 22, and 23, after the first electrode body 201 and the second electrode body 202 are inserted into the case body 110, the current collector 420 is electrically connected to the positive electrode terminal 302 (step S9).

[0124] Specifically, the positive electrode terminal 302 and the current collector 450 are attached 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 case body 110, the current collector 450 is brought into contact with the current collector 420 protruding from the opening 114 in the X direction. The connection of the plate-like member 304 to the positive electrode terminal 302 may be made at any time.

[0125] As shown in Fig. 24, the positive electrode tab group 250 and the positive electrode tab group 280 connected to the current collector 420 are bent so that the tip portions 252, 282 face each other. From the state shown in Fig. 24, the sealing plate 130 is brought into contact with the case body 110. At this time, the sealing plate 130 and the main body of the electrode assembly 200 are brought closer to each other, thereby bending the positive electrode tab group 250 and the positive electrode tab group 280. As shown in Fig. 12, the positive electrode tab group 250 and the positive electrode tab group 280 are bent along the shape of the spacer 600 so that the folded-back portions of the curved portions 251, 281 approach the case body 110 in the Y direction.

[0126] After the sealing plate 130 is brought into contact with the case body 110, the sealing plate 130 is temporarily welded to the case body 110. By temporarily joining, the sealing plate 130 is partially joined to the opening 114 of the case body 110. As a result, the sealing plate 130 is positioned relative to the case body 110.

[0127] 25 is a perspective view showing the configuration of the secondary battery 1. As shown in FIGS. 13 and 25, next, the sealing plate 120 and the sealing plate 130 are joined to the case body 110 (step S10). The sealing plate 120 seals the opening 113 of the case body 110, and the 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.

[0128] After the above steps, inspections such as a leak inspection are performed (step S11). After the leak inspection, the secondary battery 1 is dried to remove moisture from inside the case 100. Then, electrolyte is injected into the inside of the case 100 through the liquid injection hole 134. When injecting the electrolyte, the case 100 is tilted with the sealing plate 130 facing up and the sealing plate 120 facing down, and the electrolyte is injected into the inside of the case 100 through the liquid injection hole 134 of the sealing plate 130. Then, degassing charging is performed. The liquid injection hole 134 may be temporarily sealed during degassing charging. The liquid injection hole 134 is then sealed, and the secondary battery 1 is completed.

[0129] The order of the step of inserting the electrode body 200 and the step of connecting the current collectors to each other is not limited to the example described above. For example, after only a portion of the electrode body 200 is inserted into the case body 110 (first step) so that the end of the negative electrode active material layer 212 (second electrode active material layer) on the opening 113 side is disposed outside the case body 110, the negative electrode terminal 301 (first electrode terminal) provided on the sealing plate 120 (first sealing plate) and the negative electrode tab groups 220, 270 (first electrode tabs) may be electrically connected, and then the electrode body 200 may be inserted into the case body 110 until the end of the negative electrode active material layer 212 on the opening 113 side is disposed inside the case body 110 (second step). In other words, the negative electrode terminal 301 and the electrode body 200 may be electrically connected during the step of inserting the electrode body 200 into the case body 110.

[0130] In this embodiment, by providing a negative electrode tab group 220 and a positive electrode tab group 250 in the first electrode body 201 and providing a negative electrode tab group 270 and a positive electrode tab group 280 in the second electrode body 202, it is possible to configure the first electrode body 201 and the second electrode body 202 to have separate electrode tabs.

[0131] With this configuration, the first electrode body 201 and the second electrode body 202 form a single electrode tab, and the electrode tab can be made shorter than when this electrode tab is bent.

[0132] As a result, the volume occupied by the electrode tabs can be reduced, thereby improving the energy density of the secondary battery 1. Furthermore, in the configuration in which separate electrode tabs are provided for the first electrode body 201 and the second electrode body 202, the electrode tabs are easier to bend compared to when a single electrode tab is formed by the first electrode body 201 and the second electrode body 202, making it easier to join the electrode tabs to the current collectors and allowing for stable production of the secondary battery. In particular, stable production of the secondary battery 1 can increase the reliability of the connection between the electrode tabs and the current collectors.

[0133] (Specific form of insulating sheet) Specific forms of insulating sheet 700 will be described with reference to Fig. 26 to Fig. 30. In some of the drawings, the shape and cross-sectional shape of secondary battery 1 are illustrated schematically without taking into consideration actual dimensional relationships in order to facilitate understanding of the structure. Fig. 26 is a cross-sectional view of the secondary battery shown in Fig. 25 taken along line XXVI-XXVI, Fig. 27 is a cross-sectional view of the secondary battery shown in Fig. 25 taken along line XXVII-XXVII, Fig. 28 is a development view of insulating sheet 700, Fig. 29 is a reference cross-sectional view corresponding to the cross-section XXVI-XXVI of the secondary battery shown in Fig. 25, and Fig. 30 is a reference cross-sectional view corresponding to the cross-section XXVI-XXVI of the secondary battery shown in Fig. 25.

[0134] 26 and 27, the insulating sheet 700 is provided inside the case body 110 so as to cover the outer surfaces of the electrode body 200 (first electrode body 201, second electrode body 202). The insulating sheet 700 is preferably made of a single sheet, and the single insulating sheet 700 may be wrapped around the electrode body 200. As will be described later, the first region R1 and second region R2 of the insulating sheet 700 overlap to provide an overlapping region OR.

[0135] 28, insulating sheet 700 is a single rectangular sheet when unfolded. It can be divided into a first region R1, a second region R2, a third region R3, a fourth region R4, and a fifth region R5 along a direction perpendicular to the width direction (X direction) of electrode body 200. In insulating sheet 700, first region R1 is formed near one end of the sheet, and second region R2 is formed near the other end of the sheet.

[0136] In the width direction (X direction) of the electrode body 200, the overlapping region OR includes a central region CR and edge regions PR located on both sides of the central region CR, and the central region CR is provided with a non-overlapping region that reduces the area of ​​the overlapping region OR.Here, in this embodiment, the central region CR of the insulating sheet 700 is approximately 80% in the center in the horizontal direction (width direction of the electrode body 200), and the remaining approximately 10% on both sides are the edge regions PR.

[0137] A non-overlapping region that reduces the area of ​​the overlapping region OR means a region in which, when a non-overlapping region is provided, the shape of the second region R2 in the central region CR is changed, thereby reducing the area of ​​the overlapping region OR, compared to a state in which there is no change in the shape of the second region R2 in the horizontal direction in the central region CR and the edge region PR.

[0138] In the second region R2 of the insulating sheet 700 of this embodiment, the central region CR has recesses 710s as non-overlapping regions on the circumferential edges thereof that are recessed inward from the edges of the end regions. Various shapes of the recesses 710s can be adopted, but it is preferable that the proportion of the non-overlapping region in the central region CR relative to the overlapping area in the case where the recesses 710s as non-overlapping regions are not provided is 20% or more.

[0139] The width of the recess 710s is preferably approximately 30% or more, and more preferably 50% or more, of the overall width of the main body of the electrode assembly 200. The length of the main body of the electrode assembly 200 refers to the length excluding the lengths of the negative electrode tab group and the positive electrode tab group provided on both sides of the electrode assembly 200. The width of the recess 710s is the width of its widest portion. For example, in the case where the recess 710s has a shape in which its width increases toward the tip of the second region R2 (the upper end in FIG. 28) as shown in FIG. 28, the width is the width of the recess 710s at a position corresponding to the tip of the second region R2 (the upper end in FIG. 28).

[0140] The insulating sheet 700 preferably has a folding line (curvature) L1 at the boundary between each region to facilitate winding the sheet around the electrode assembly 200. If first cutout regions 711 that are recessed inward are provided at both ends of the folding line (curvature) L1 in the width direction, winding the sheet around the electrode assembly 200 will be even easier. The shape of the first cutout regions 711 is shown as semicircular in the figure, but may also be trapezoidal, rectangular, triangular, or other shapes.

[0141] In order to facilitate connection to the spacer 600 (described later), second cutouts 712 recessed inward may be provided at both widthwise ends of the first region R1 of the insulating sheet 700. While the second cutouts 712 are shown rectangular in the drawing, they may also be semicircular, trapezoidal, rectangular, triangular, or other shapes. Furthermore, instead of being cutouts that are open on one side as shown in the drawing, they may also be in the shape of through holes.

[0142] The angle (α) formed between the side edges 710s1 at both ends of the recess 710s and the edge 710t of the end region PR is preferably 100 degrees or more, which makes it possible to prevent the insulating sheet 700 from getting caught when the electrode body 200 wrapped around the insulating sheet 700 is inserted into the case body 110.

[0143] As described above, the insulating sheet 700 may be made of, for example, resin. More specifically, the material of the insulating sheet 700 may be, for example, polypropylene (PP), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyimide (PI), or polyolefin (PO). The thickness of the insulating sheet 700 is preferably thicker than the thickness of the separator 800 (5 μm to 20 μm).

[0144] 26 and 27, the electrode body 200 has a pair of a first surface 21 and a third surface 23 corresponding to the height direction (Z direction) of the secondary battery 1, and a pair of a second surface 22 and a fourth surface 24 corresponding to the thickness direction (Y direction) of the secondary battery 1. The areas of the first surface 21 and the third surface 23 are preferably smaller than the areas of the second surface 22 and the fourth surface 24, respectively.

[0145] The electrode assembly 200 can be a stacked electrode assembly including multiple positive electrode plates and multiple negative electrode plates. In this case, the first surface 21 is the surface on which the end faces of the positive electrode plates and the negative electrode plates are arranged. However, the end faces of the positive electrode plates or the negative electrode plates may be covered with a separator. Furthermore, the end faces of the positive electrode plates and the negative electrode plates may be misaligned. The separator may be multiple rectangular separators, a strip-shaped separator folded zigzag, or another form.

[0146] When the insulating sheet 700 is wrapped around the electrode body 200, the first region R1 and the second region R2 face the first surface 21, the third region R3 faces the second surface 22, the fourth region R4 faces the third surface 23, and the fifth region R5 faces the fourth surface 24. The first region R1 and the second region R2 cover the first surface 21, and there is an overlapping region OR where the second region R2 overlaps the first region R1. Note that in the first region R1 to the fifth region R5, the boundary between adjacent regions becomes a folded portion.

[0147] The tip of the second region R2 is preferably spaced apart from the bent portion between the first region R1 and the fourth region R4 (the outer surface of the fourth region R4) (distance H1 in the figure). The distance H1 is preferably 5% or more, and more preferably 10% or more, of the thickness of the electrode body 200.

[0148] When the insulating sheet 700 having the above-described configuration is wrapped around the electrode body 200, as shown in FIG. 26, the first region R1 is positioned on the side in contact with the spacer 600, and the second region R2 is wrapped so as to be above the first region R1.

[0149] In the region where the spacers 600 (first spacer, second spacer) provided on both sides are located, the insulating sheet 700 is connected to the spacers 600 (first spacer, second spacer) by utilizing the second cutout region 712 provided in the first region R1. When connecting the insulating sheet 700 to the spacers 600, a connecting means such as heat welding, ultrasonic welding, taping, adhesive bonding, fitting, hooking, etc. is used.

[0150] 26, it is preferable that the region of the second region R2 facing the second cutout 712 is connected to the spacer 600 through the second cutout 712 to provide the connection portion 740. As described above, the second cutout 712 may be replaced with a through hole or the like.

[0151] When connecting the insulating sheet 700 to the spacer 600, the second cutout region 712 provided in the first region R1 is used, so that the second region R2 is directly fixed to the spacer 600 while pressing the first region R1 with the second region R2. As a result, the insulating sheet 700 can be stably and easily fixed to the spacer 600.

[0152] When a configuration in which the spacer 600 is not provided is adopted, the first region R1 and the second region R2 are connected in the regions at both ends where the second cutout regions 712 are provided, using the above-mentioned connection method.

[0153] When the insulating sheet 700 having the above configuration is wrapped around the electrode assembly 200, as shown in Figures 26 to 29, it is preferable that the proportion of the overlapping portion between the first region R1 and the second region R2 in the region corresponding to the central region of the first surface 21 of the electrode assembly 200 is greater than the proportion of the overlapping portion between the first region R1 and the second region R2 in the region corresponding to the edge region of the first surface 21 of the electrode assembly 200. By providing a certain degree of overlap between the first region R1 and the second region R2, it is possible to stabilize the positional relationship between the insulating sheet 700 and the electrode assembly 200 and to increase the impregnation of the electrolyte into the central region of the electrode assembly 200. Note that the present disclosure is particularly effective for batteries with high capacity (for example, a battery capacity of 50 Ah or more).

[0154] Providing the spacer 600 can more effectively stabilize the positional relationship between the insulating sheet 700 and the electrode body 200. When the insulating sheet 700 having the above configuration is wrapped around the electrode body 200, in the overlapping portion between the first region R1 and the second region R2, as shown in Fig. 26, a large proportion of the overlapping area between the first region R1 and the second region R2 is ensured in the edge region PR, and in the recess 710s, the proportion of the overlapping area between the first region R1 and the second region R2 is smaller than that in the edge region PR.

[0155] As a result, in the end region PR, the wrapping area of ​​the insulating sheet 700 around the spacer 600 is ensured, and it is possible to stabilize the wrapping state of the insulating sheet 700 around the spacer 600. On the other hand, by providing the recess 710s, the overlapping area is reduced and a gap is generated between the first region R1 and the second region R2.

[0156] This overlapping state that reduces the overlapping area shortens the path through which the electrolyte (arrow R10 in FIG. 26) enters the electrode body 200 during the secondary battery manufacturing process, facilitating the electrolyte's entry into the interior. As a result, it is possible to prevent the electrolyte from being obstructed from entering. For example, as shown in FIG. 29, when the overlap length between the first region R1 and the second region R2 increases, the path through which the electrolyte (arrow R10 in FIG. 30) enters the electrode body 200 becomes longer, making it easier for the electrolyte's entry to be obstructed.

[0157] Thus, the structure of the secondary battery 1 in the embodiment can prevent direct contact between the electrode assembly 200 and the case body 110, while preventing impregnation of the electrolyte into, and movement of the electrolyte in and out of, the electrode assembly 200 from being hindered. As a result, a secondary battery 1 can be provided that has improved permeability of the electrolyte into the high-capacity, high-density electrode assembly 200.

[0158] 5, the case body 110 is provided with a gas exhaust valve 150, and it is preferable that this surface be disposed opposite the first surface 21 of the electrode assembly 200. The gas exhaust valve 150 breaks when the internal pressure of the case body 110 reaches a predetermined level or higher, and exhausts the gas inside the case body 110 to the outside of the case body 110. Therefore, a smaller overlapping area between the first region R1 and the second region R2 of the insulating sheet 700 makes it possible to more efficiently exhaust the gas generated from the electrode assembly 200 to the outside of the case body 110.

[0159] 28, the width W1 of the recess 710s is preferably 50% or more, more preferably 70% or more, and even more preferably 80% or more of the overall width W of the insulating sheet 700. This allows gas generated from the electrode body 200 to be efficiently discharged to the outside.

[0160] The insulating sheet 700 described above has a configuration in which recesses 710s are provided in the outer second region R2, but the same effect can be obtained by providing recesses 710s in the inner first region R1, as shown in Figure 30.

[0161] (Specific form of recess 710s) Next, with reference to FIG. 31, a specific form of the recess 710s constituting the non-overlapping region provided in the second region R2 will be described. FIG. 31 shows the area of ​​each region when viewed from the first surface 21 side of the electrode assembly 200 (when viewed from a direction perpendicular to the first surface 21), and illustrates: [1] the area (Sh2) of the second region R2 of the insulating sheet 700; [2] the area (Ss1) of the spacer 600 (first spacer); [3] the area (Sh1) of the first region R1 of the insulating sheet 700; and [4] the area (So1) of the region where the first region R1 and the second region R2 of the insulating sheet 700 overlap. Note that the area of ​​the electrode assembly 200 excludes the areas of the positive electrode tab group and the negative electrode tab group. The case main body 110 is not shown in FIG. 32.

[0162] When the area of ​​each region is specified in this way, if the ratio of [area of ​​the region where the spacer 600 (first spacer), the first region R1, and the second region R2 overlap] / [(area of ​​the spacer 600 (first spacer) (Ss1)] is X1, and the ratio of [area of ​​the region where the region not overlapping with the spacer 600 (first spacer), the first region R1, and the second region R2 overlap in the electrode body 200] / [(area of ​​the region not overlapping with the spacer 600 (first spacer) (Se1)] is Y1, then X1 should be set to be larger than Y1. The same applies if the spacer 600 (first spacer) is replaced with the spacer 600 (second spacer).

[0163] In this way, it is preferable that the proportion of the overlapping area between the first region R1 and the second region R2 in the region overlapping with the spacer 600 is greater than the proportion of the overlapping area between the first region R1 and the second region R2 in the region overlapping with the electrode body 200.

[0164] Specifically, X1 is preferably 0.5 or more, more preferably 0.6 or more, and even more preferably 0.7 or more. Y1 is preferably less than 0.5, more preferably 0.4 or less, and even more preferably 0.3 or less. For example, Y1 is preferably 0.03 or more, and more preferably 0.05 or more.

[0165] It is sufficient that only one of the first spacer side and the second spacer side satisfies the above relationship. However, it is preferable that both the first spacer side and the second spacer side satisfy the above relationship. It is not necessary to have both the first spacer and the second spacer, and only one of them may be provided.

[0166] Here, the above numerical values ​​are for the case where spacers 600 (first spacer, second spacer) are provided, but Fig. 32 explains a case where optimization of the area (So1) of the region where the first region R1 and the second region R2 overlap, regardless of the presence or absence of the spacer 600. Fig. 32 is a diagram showing the central region CR and the end region when viewed from the side of the first surface 21 of the electrode body 200. Note that the case body 110 is not shown in Fig. 32.

[0167] Referring to Figure 32, regardless of whether or not a spacer 600 is present, when viewed from the first surface 21 side of the electrode body 200, the central region CR refers to the region from minus 25% to plus 25% (minus refers to the left side in the figure, plus refers to the right side in the figure) from the center line (CL) of the insulating sheet 700 (electrode body 200), and the end region refers to the region 10% from the end of the insulating sheet 700.

[0168] In the above case, if the ratio of [area of ​​overlapping portion of first region R1 and second region R2 in end region (region 10% from end)] / [area of ​​end region (region 10% from end)] is X2 and the ratio of [area of ​​overlapping portion of first region R1 and second region R2 in central region CR (region minus 25% to plus 25% from the center)] / [area of ​​central region CR (region minus 25% to plus 25% from the center)] is Y2, it is preferable that X2 is set larger than Y2.

[0169] Specifically, X2 is preferably 0.5 or more, more preferably 0.6 or more, and even more preferably 0.7 or more. Y2 is preferably less than 0.5, more preferably 0.4 or less, and even more preferably 0.3 or less. For example, Y2 is preferably 0.03 or more, and more preferably 0.05 or more.

[0170] 33, a case will be described in which recesses 710s are provided in the first region R1 in the second region R2 located on the outside of the insulating sheet 700 facing the first surface 21 of the electrode body 200 and the first region R1 located on the inside. Fig. 33 corresponds to a partial enlarged view of the first surface 21 side of the electrode body 200 shown in Fig. 30.

[0171] If a recess 710s is provided on the inside, there is a risk that the electrolyte will accumulate in the gap S1 that occurs between the insulating sheet 700 and the case body 110. Therefore, the length L1 in the thickness direction of the electrode body 200 of the second region R2 located on the case body 110 side is preferably 90 or more, where the thickness of the electrode body 200 is 100. On the other hand, the length L2 of the first region R1 located on the electrode body 200 side is preferably 20 or less, where the thickness of the electrode body 200 is 100, to ensure an internal space through which the electrolyte can flow and to allow a large amount of electrolyte to be injected at one time.

[0172] (Embodiment 2: Insulating sheet 700A) Another embodiment of the insulating sheet will be described with reference to Fig. 34. As long as an area equivalent to the function required for the non-overlapping area that reduces the overlapping area of ​​the overlapping area provided in the central region CR of the above-described insulating sheet 700 is provided, the shape is not limited to the recess 710s. Fig. 34 is a development view showing the shape of insulating sheet 700A according to the second embodiment.

[0173] In this insulating sheet 700A, a plurality of through holes 720 are provided in the central region CR instead of the recesses 710s that form the non-overlapping region. The shape of the through holes 720 is not particularly limited, and various shapes such as a circle, an ellipse, or a rectangle can be adopted. Note that it is sufficient that the through holes 720 are formed in at least one of the first region R1 or the second region R2.

[0174] In this way, even when a plurality of through holes 720 are used as the non-overlapping region, it is possible to achieve the same effects as those of insulating sheet 700 in the first embodiment.

[0175] (Embodiment 3: Insulating sheet 700B) Another embodiment of the insulating sheet will be described with reference to Fig. 35. Fig. 35 is a development view showing the configuration of an insulating sheet 700B according to the third embodiment.

[0176] In the insulating sheet 700 shown in FIG. 28, recesses 710s are provided over the entire central region CR, but in the insulating sheet 700B of the present embodiment, recesses 710s are provided not over the entire central region CR but only in part of the central region CR.

[0177] Even with this configuration of recesses 710s, it is possible to achieve the same effects as those of insulating sheet 700 in the first embodiment.

[0178] (Embodiment 4: Insulating sheet 700C) Another embodiment of the insulating sheet will be described with reference to Fig. 36. Fig. 36 is a development view showing the configuration of an insulating sheet 700C according to the fourth embodiment.

[0179] In this embodiment, the recesses 710s provided in the central region CR are divided into two locations, but the number of locations is not limited to two, and the recesses 710s may be divided into three or more locations.

[0180] In this way, even when recesses 710s are provided in a plurality of separate portions, the same effects as those of insulating sheet 700 in the first embodiment can be achieved.

[0181] Although the embodiments of the present technology have been described above, the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present technology is defined by the claims, and it is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0182] 1 secondary battery, 21 first surface, 22 second surface, 23 third surface, 24 fourth surface, 100 case, 110 case body, 111 first side portion, 112 second side portion, 112A second side portion, 112B second side portion, 113, 114 opening, 115 joint portion, 120, 130 sealing plate, 134 liquid inlet, 150 gas release 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, 212 negative electrode active material layer, 220, 270 negative electrode tab group, 221, 271 curved portion, 222, 272 tip portion, 230 Negative electrode tab, 240 positive electrode plate, 241 positive electrode core, 242 positive electrode active material layer, 243 positive electrode protective layer, 250, 280 positive electrode tab group, 251, 281 curved portion, 252, 282 tip portion, 260 positive electrode tab, 300 electrode terminal, 301 negative electrode terminal, 302 positive electrode terminal, 303, 304 plate-shaped member, 400, 410, 420, 430, 440, 450 current collector, 400A negative electrode current collector, 400B positive electrode current collector, 410q protruding portion, 410q1 tip surface, 410q2 outer surface, 411, 421 joint portion, 430p recess, 430p1 bottom surface, 430p2 inner surface, 460 Plate, 470, 510, 520, 530 insulating member, 600 spacer, 611 connecting wall, 612 first part, 612p first convex portion, 614 second part, 614p second convex portion, 616 convex portion, 617 first plate portion, 617s first through hole, 618 second plate portion, 618s second through hole, 700, 700A, 700B, 700C insulating sheet, 710s recess, 710s1 side edge, 710t end edge, 711 first cutout region, 720 through hole, 800 separator.

Claims

1. An electrode body including a first electrode and a second electrode having a different polarity from the first electrode, A battery case housing the electrode body, A group of first electrode tabs, electrically connected to the first electrode and positioned at one end of the electrode body, A group of second electrode tabs, electrically connected to the second electrode and positioned at the other end of the electrode body, The electrode body comprises an insulating sheet covering the electrode body, The electrode body includes a first surface, The insulating sheet includes a first region formed near one end and a second region formed near the other end. The first region and the second region cover the first surface, An overlapping region is provided in which the second region overlaps the first region. In the width direction of the electrode body, the overlapping region includes a central region and end regions located on both sides of the central region. The central region has a non-overlapping region that reduces the overlapping area of ​​the overlapping region. Secondary battery.

2. In the aforementioned central region, the ratio of the non-overlapping area to the overlapping area if the non-overlapping area were not provided is 20% or more. The secondary battery according to claim 1.

3. At least one of the first and second regions has, in the central region, a non-overlapping region, which has a recess at its circumferential edge that is recessed inward from the edge of the end region. The secondary battery according to claim 1.

4. The recess is provided in the second region. The secondary battery according to claim 3.

5. The angle between the sides at both ends of the recess and the edge of the end region is 100 degrees or more. The secondary battery according to claim 3.

6. A first spacer is provided on the end face of the electrode body on which the first electrode tab group is provided, A second spacer is provided on the end face of the electrode body on which the second electrode tab group is located, It further includes, On the side where the first electrode tab group is provided, the insulating sheet and the first spacer are connected. On the side where the second electrode tab group is provided, the insulating sheet and the second spacer are connected. The secondary battery according to claim 1.

7. In terms of the area of ​​the electrode body as viewed from the side of the first surface, Let X1 be the ratio of [area of ​​the region where the first spacer, the first region, and the second region overlap] / [area of ​​the first spacer]. When Y1 is defined as the ratio of [area of ​​the region where the electrode body, the first region, and the second region overlap] / [area of ​​the electrode body], The aforementioned X1 is greater than the aforementioned Y1. The secondary battery according to claim 6.

8. To connect the insulating sheet to the first spacer, The first region has an opening or a notch, The second region is the region opposite to the opening or notch and is connected to the first spacer. The secondary battery according to claim 6.

9. In terms of the area of ​​the electrode body as viewed from the side of the first surface, Let X2 be the ratio of [area of ​​the overlapping portion between the first region and the second region in the end region] / [area of ​​the end region]. When the ratio of [area of ​​the overlapping portion between the first and second regions in the central region] / [area of ​​the central region] is Y2, The aforementioned X2 is greater than the aforementioned Y2. The secondary battery according to claim 1.

10. The electrode body has a first surface and a third surface adjacent to it. The insulating sheet has a fourth region that covers the third surface, A bent portion is provided between the first region and the fourth region. The tip of the second region is located away from the bent portion. The secondary battery according to claim 1.

11. The battery case is provided with a gas discharge valve. In the battery case, the surface on which the gas discharge valve is provided faces the first surface. The secondary battery according to claim 1.

12. The aforementioned battery case is A case body having a first opening at one end and a second opening at the other end, A first sealing plate that seals the first opening and is welded to the case body, The case includes a second sealing plate that seals the second opening and is welded to the case body, The first electrode tab group is arranged at the first opening end of the electrode body, The second electrode tab group is located at the second opening end of the electrode body. The secondary battery according to claim 1.

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