Secondary battery

Abstract

The present invention relates to a secondary battery. The secondary battery includes an insulating sheet covering an electrode body, the electrode body including a first surface, the insulating sheet including a first region formed in the vicinity of one end portion and a second region formed in the vicinity of the other end portion, the first region and the second region covering the first surface, and an overlapping region in which the second region overlaps the first region is provided. 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 recess as a non-overlapping region that reduces the overlapping area of the overlapping region.

Description

Technical Field

[0001] The present technology relates to secondary batteries. Background Art

[0002] Japanese Patent No. 4537353 discloses a rectangular battery having a positive electrode terminal provided on one side surface of a battery case and a negative electrode terminal provided on the other end. Summary of the Invention

[0003] By creating a rectangular battery with a positive terminal on one side of the battery casing and a negative terminal on the other end, a low-profile battery pack can be easily manufactured. However, there is room for further improvement to achieve efficient and stable battery manufacturing. For example, in order to allow the electrolyte to penetrate the high-capacity, high-density electrode body, it is necessary to inject the electrolyte over a long period of time or in multiple steps.

[0004] An object of the present technology is to provide a secondary battery capable of improving the permeability of an electrolyte solution into an electrode body.

[0005] The present technology provides the following secondary batteries.

[0006] [1] A secondary battery comprising: an electrode body including a first electrode and a second electrode having a polarity different from that of the first electrode; a battery case housing the electrode body; a first electrode tab group electrically connected to the first electrode and disposed at one end of the electrode body; a second electrode tab group electrically connected to the second electrode and disposed at the other end of the electrode body; and an insulating sheet covering the electrode body, wherein 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 covering the first surface, and an overlapping region in which the second region overlaps the first region.

[0007] 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 includes a non-overlapping region for reducing an overlapping area of the overlapping region.

[0008] [2] The secondary battery according to [1], wherein in the central region, the ratio of the non-overlapping region to the overlapping area when the non-overlapping region is not provided is 20% or more.

[0009] [3] The secondary battery according to [1] or [2], wherein at least one of the first region and the second region has a concave portion as the non-overlapping region at the circumferential end side of the central region that is recessed inwardly from the end side of the end region.

[0010] [4] The secondary battery according to [3], wherein the recess is provided in the second region.

[0011] [5] The secondary battery according to [3] or [4], wherein the angle formed by the side edges at both ends of the recess and the end edge of the end region is 100 degrees or greater.

[0012] [6] The secondary battery according to any one of [1] to [5] further includes: a first separator, the first separator being arranged on the end surface of the electrode body on which the first electrode tab group is provided; and a second separator, the second separator being arranged on the end surface of the electrode body on which the second electrode tab group is provided, the insulating sheet being connected to the first separator on the side on which the first electrode tab group is provided, and the insulating sheet being connected to the second separator on the side on which the second electrode tab group is provided.

[0013] [7] According to the secondary battery described in [6], in the area when viewed from the above-mentioned first surface side of the above-mentioned electrode body, when the ratio of [the area of the region where the above-mentioned first spacer, the above-mentioned first region and the above-mentioned second region overlap] / [the area of the above-mentioned first spacer] is set to X1, and the ratio of [the area of the region where the above-mentioned electrode body, the above-mentioned first region and the above-mentioned second region overlap] / [the area of the above-mentioned electrode body] is set to Y1, the above-mentioned X1 is larger than the above-mentioned Y1.

[0014] [8] The secondary battery according to [6] or [7], wherein the first region has an opening or a cutout to connect the insulating sheet to the first separator, and the second region is connected to the first separator in a region facing the opening or the cutout.

[0015] [9] The secondary battery according to any one of [1] to [8], wherein, in the area when viewed from the first surface side of the electrode body, when the ratio of [the area of the overlapping portion between the first region and the second region in the end region] / [the area of the end region] is set to X2 and the ratio of [the area of the overlapping portion between the first region and the second region in the central region] / [the area of the central region] is set to Y2, the above X2 is larger than the above Y2.

[0016]

[10] According to any one of [1] to [9], the secondary battery, 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 bending portion is provided between the first region and the fourth region, and the front end of the second region is located away from the bending portion.

[0017]

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

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

[0018]

[12] According to any one of [1] to

[11] , the secondary 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, the first sealing plate sealing the first opening and being welded to the case body; and a second sealing plate, the second sealing plate sealing the second opening and being welded to the case body, the first electrode tab group being arranged at the end of the electrode body on the first opening side, and the second electrode tab group being arranged at the end of the electrode body on the second opening side.

[0019] The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a front view showing the structure of the secondary battery according to the first embodiment.

[0021] Figure 2 It means observing from the direction of arrow II Figure 1 The diagram shows the state of the secondary battery.

[0022] Figure 3 It means observing from the direction of arrow III Figure 1 The diagram shows the state of the secondary battery.

[0023] Figure 4 It means observing from the direction of arrow IV Figure 1 The diagram shows the state of the secondary battery.

[0024] Figure 5 It indicates viewing from the direction of arrow V Figure 1 The diagram shows the state of the secondary battery.

[0025] Figure 6 yes Figure 1 A front cross-sectional view of a secondary battery is shown.

[0026] Figure 7 It is a cross-sectional view of the negative plate.

[0027] Figure 8 It is a front view showing the negative electrode plate.

[0028] Figure 9 It is a cross-sectional view of the positive plate.

[0029] Figure 10 It is a front view showing the positive electrode plate.

[0030] Figure 11 yes Figure 1 XI-XI cross-sectional view of the secondary battery shown.

[0031] Figure 12 yes Figure 1 The secondary battery is shown in a cross-sectional view taken along line XII-XII.

[0032] Figure 13 This is a flowchart showing a method for manufacturing a secondary battery according to one embodiment.

[0033] Figure 14 This is a perspective view showing a state before two electrode bodies included in a secondary battery according to one embodiment are stacked.

[0034] Figure 15 yes Figure 14 The electrode body and the current collector are shown in a cross-sectional view taken along the line XV-XV.

[0035] Figure 16 It is a perspective view showing a state where a holder and a spacer are attached to an electrode assembly.

[0036] Figure 17 It is a perspective view showing a state where a sealing plate is attached to the current collector on the negative electrode side.

[0037] Figure 18 yes Figure 17 The electrode body and the current collector are shown in cross-sectional view taken along line XVIII-XVIII.

[0038] Figure 19 This is a first perspective view showing the configuration of the spacer.

[0039] Figure 20 This is a second perspective view showing the configuration of the spacer.

[0040] Figure 21 It is a side view showing the positional relationship between the spacer and the insulating sheet.

[0041] Figure 22 It is a perspective view showing a state where the electrode assembly is inserted into the case body.

[0042] Figure 23 It is a perspective view showing a state where a sealing plate is attached to the current collector on the positive electrode side.

[0043] Figure 24 yes Figure 23 XXIV-XXIV cross-sectional view of the electrode body and current collector shown.

[0044] Figure 25It is a perspective view showing the structure of a secondary battery.

[0045] Figure 26 yes Figure 25 XXVI-XXVI cross-sectional view of the secondary battery shown.

[0046] Figure 27 yes Figure 25 XXVII-XXVII cross-sectional view of the secondary battery shown.

[0047] Figure 28 This is an expanded view of the insulation sheet.

[0048] Figure 29 is with Figure 25 This is a reference cross-sectional view corresponding to the section XXVI-XXVI of the secondary battery shown.

[0049] Figure 30 is with Figure 25 This is a reference cross-sectional view corresponding to the section XXVI-XXVI of the secondary battery shown.

[0050] Figure 31 It is a diagram showing the area of each region when viewed from the first surface side of the electrode body.

[0051] Figure 32 It is a diagram showing the central region and the end region when viewed from the first surface side of the electrode body.

[0052] Figure 33 yes Figure 30 A partially enlarged view of the first surface side of the electrode body is shown.

[0053] Figure 34 This is a development view of the insulating sheet according to the second embodiment.

[0054] Figure 35 This is a development view of the insulating sheet according to the third embodiment.

[0055] Figure 36 This is a development view of the insulating sheet according to the fourth embodiment. DETAILED DESCRIPTION

[0056] Hereinafter, embodiments of the present technology will be described. It should be noted that the same reference numerals are given to the same or corresponding parts, and their description may not be repeated.

[0057] 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 embodiments described below, individual components are not necessarily essential to the present technology unless otherwise specified. Furthermore, the present technology is not limited to technologies that necessarily achieve all the effects described in the embodiments.

[0058] In this specification, the terms “comprise,” “include,” and “have” are open-ended. That is, when a certain structure is included, other structures other than that structure may or may not be included.

[0059] In this specification, when geometric terms and terms indicating positional / directional relationships are used, such as "parallel," "orthogonal," "inclined at 45°," "coaxial," and "along," these terms allow for manufacturing errors and slight variations. In this specification, when terms such as "upper" and "lower" are used to indicate relative positional relationships, these terms are used to indicate a specific relative positional relationship. The relative positional relationship can be reversed or rotated to any angle depending on the orientation of the mechanism (for example, by turning the entire mechanism upside down).

[0060] In this specification, "secondary battery" is not limited to lithium-ion batteries, and may include other secondary batteries such as nickel-metal hydride batteries and sodium-ion batteries. In this specification, "electrode" may be collectively referred to as positive electrode and negative electrode.

[0061] In the accompanying drawings, if the electrode assembly of the secondary battery is a stacked electrode assembly, the longitudinal direction of the stacked surface is designated as the X direction. If the electrode assembly is a wound electrode assembly, the direction along the winding axis is designated as the X direction. Furthermore, when viewed from the X direction, the shorter side of the electrode assembly is designated as the Y direction, and when viewed from the X direction, the longer side of the electrode assembly is designated as the Z direction. To facilitate understanding of the invention, the dimensions of various components in the drawings may be modified from their actual dimensions.

[0062] In this application specification, the first direction (X direction) is sometimes referred to as the "width direction" of the secondary battery, electrode body, and shell body, and the second direction (Z direction) is similarly referred to as the "height direction" of the secondary battery or the shell body, and the third direction (Y direction) is similarly referred to as the "thickness direction" of the secondary battery or the shell body.

[0063] (Embodiment 1: Overall structure of a battery)

[0064] Figure 1 It is a front view of the secondary battery 1 according to the first embodiment. Figures 2 to 5They are respectively viewed from the direction of arrow II, arrow III, arrow IV, and arrow V. Figure 1 The diagram shows the state of the secondary battery 1. Figure 6 yes Figure 1 The secondary battery 1 is shown in front cross-sectional view.

[0065] The secondary battery 1 can be mounted on a battery electric vehicle (BEV), a plug-in hybrid electric vehicle (PHEV), a hybrid electric vehicle (HEV), etc. However, the use of the secondary battery 1 is not limited to vehicle use.

[0066] like Figures 1 to 6 As shown, the secondary battery 1 includes a case 100, an electrode body 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).

[0067] When constructing a battery pack including secondary batteries 1, multiple secondary batteries 1 are stacked in the thickness direction. The stacked secondary batteries 1 can be constrained in the stacking direction (Y direction) by restraining members to form a battery module. Alternatively, the battery pack can be directly supported on the side of the battery pack casing without using restraining members.

[0068] The case body 110 is formed of a cylindrical, preferably rectangular, member. This provides a rectangular secondary battery 1. The case body 110 is made of metal. Specifically, the case body 110 is formed of aluminum, an aluminum alloy, iron, or an iron alloy.

[0069] like Figure 1 as well as Figure 2 As shown, a sealing plate 120 (first wall) and a sealing plate 130 (second wall) are provided at both ends of the housing body. The housing body 110 can be formed by, for example, placing the ends of the plate-shaped members that have been bent in contact with each other ( Figure 2 The illustrated joint 115 is joined together (e.g., laser welding) to form a rectangular cylindrical shape. The corners of the "rectangular cylindrical shape" may also have an R shape (rounded corners). Furthermore, the secondary battery in this technology is not necessarily limited to a rectangular secondary battery.

[0070] 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 X-direction dimension (width) of the case body 110 is preferably 30 cm or greater. This allows for a relatively large (high-capacity) secondary battery 1. The Z-direction dimension (height) of the case body 110 is preferably 20 cm or less, more preferably 15 cm or less, and even more preferably 10 cm or less. This allows for a relatively low-height secondary battery 1, improving its fitment in a vehicle, for example.

[0071] The shell body 110 includes a pair of first side portions 111 and a pair of second side portions 112. The pair of first side portions 111 constitute a portion of the side surface of the shell 100. The pair of second side portions 112 constitute the bottom surface and the upper surface of the shell 100. The pair of first side portions 111 and the pair of second side portions 112 are respectively arranged to intersect with each other. The pair of first side portions 111 and the pair of second side portions 112 are connected at their respective ends. Preferably, the area of each of the pair of first side portions 111 is larger than the area of each of the pair of second side portions 112.

[0072] like Figure 5 As shown, a gas discharge valve 150 is provided on one second side surface 112A of the pair of second side surfaces 112. Gas discharge valve 150 extends in the width direction (X direction) of secondary battery 1. Gas discharge valve 150 extends in the X direction, but does not extend from the center of case body 110 in the X direction to both ends. The shape of gas discharge valve 150 can be modified as appropriate.

[0073] The thickness of the plate-like member at the gas discharge valve 150 is thinner than the thickness of the plate-like members of the housing body 110 other than the gas discharge valve 150. Therefore, when the pressure in the housing 100 exceeds a predetermined value, the gas discharge valve 150 ruptures preferentially over other parts of the housing body 110, allowing the gas in the housing 100 to be discharged to the outside.

[0074] like Figure 2 As shown, a joint portion 115 is formed on the other second side portion 112B of the pair of second side portions 112. The joint portion 115 extends in the width direction (X direction) of the secondary battery 1. At the joint portion 115, the end edges of the plate-like members constituting the case body 110 are joined to each other.

[0075] like Figure 3As shown, an opening 113 (first opening) is provided at the end of the first side of the housing body 110 in the first direction (X direction). Opening 113 is sealed by a sealing plate 120. A joint 115 is formed in opening 113 to seal it. Opening 113 and sealing plate 120 have a generally rectangular shape with the short side in the Y direction and the long side in the Z direction. A generally rectangular shape includes a substantially rectangular shape, or a substantially rectangular shape with rounded corners, such as a rectangular shape.

[0076] The sealing plate 120 (first sealing plate) is provided with a negative electrode terminal 301. The position of the negative electrode terminal 301 can be changed as appropriate.

[0077] like Figure 4 As shown, an opening 114 (second opening) is provided at the end of the second side of the housing body 110, opposite to the first side in the first direction (X direction). Specifically, opening 114 is located at the end opposite to opening 113, and openings 113 and 114 face each other. Opening 114 is sealed by a sealing plate 130. A joint 115 is formed in opening 114, sealing it. Opening 114 and sealing plate 130 have a generally rectangular shape, with the shorter side extending in the Y direction and the longer side extending in the Z direction.

[0078] The sealing plate 130 (second sealing plate) is provided with a positive electrode terminal 302 and a liquid injection hole 134. The positions of the positive electrode terminal 302 and the liquid injection hole 134 can be changed as appropriate.

[0079] The sealing plate 120 and the sealing plate 130 are made of metal. Specifically, the sealing plate 120 and the sealing plate 130 are made of aluminum, an aluminum alloy, iron, an iron alloy, or the like.

[0080] The negative electrode terminal 301 (first electrode terminal) is electrically connected to the negative electrode of the electrode assembly 200 . The negative electrode terminal 301 is attached to the sealing plate 120 , that is, the case 100 .

[0081] The positive electrode terminal 302 (second electrode terminal) is electrically connected to the positive electrode of the electrode assembly 200 . The positive electrode terminal 302 is attached to the sealing plate 130 , that is, the case 100 .

[0082] The negative electrode terminal 301 is made of a conductive material (more specifically, a metal), such as copper or a copper alloy. A portion or layer made of aluminum or an aluminum alloy may be provided on the outer surface of the negative electrode terminal 301 .

[0083] The positive electrode terminal 302 is made of a conductive material (more specifically, metal), and can be made of, for example, aluminum or an aluminum alloy.

[0084] The liquid injection hole 134 is sealed by a sealing member (not shown). As the sealing member, for example, a blind rivet or other metal member can be used.

[0085] The electrode body 200 is a flat electrode body stacked with a positive electrode plate and a negative electrode plate described later. Specifically, the electrode body 200 is a stacked electrode body formed by alternately stacking a plurality of positive electrode plates and a plurality of negative electrode plates via a separator 800 described later. However, in this specification, the "electrode body" is not limited to a stacked electrode body, and may also be a wound electrode body formed by winding a strip-shaped positive electrode plate and a strip-shaped negative electrode plate together via a strip-shaped separator. The separator can be composed of a polyolefin microporous film, for example. In the case where the electrode body is a stacked electrode body including a plurality of positive electrode plates and a plurality of negative electrode plates, the positive electrode tabs provided on each positive electrode plate can be stacked to form a positive electrode tab group, and the negative electrode tabs provided on each negative electrode plate can be stacked to form a negative electrode tab group.

[0086] like Figure 6 As shown, the housing 100 accommodates the electrode body 200. Figure 6 , a first electrode body 201 to be described later is exemplified. The first electrode body 201 is housed in the housing 100 so that its longitudinal direction is parallel to the X direction.

[0087] Specifically, a single or multiple stacked electrode assemblies are housed inside an insulating sheet 700 (described later) within the housing 100, along with an electrolyte solution (not shown). The electrolyte solution (non-aqueous electrolyte) can be, for example, a solution containing LiPF6 dissolved at a concentration of 1.2 mol / L in a non-aqueous solvent consisting of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) at a volume ratio (at 25°C) of 30:30:40. A solid electrolyte can also be used in place of the electrolyte solution.

[0088] The first electrode body 201 includes a substantially rectangular main body, a negative electrode tab group 220 (a first electrode tab group), and a positive electrode tab group 250 (a second electrode tab group).

[0089] The main body is composed of a negative electrode plate 210 and a positive electrode plate 240, described later. The negative electrode tab group 220 is located at an end portion of the main body on a first side of the first electrode body 201 in the first direction (X direction). In this embodiment, the first side is the sealing plate 120 side. The positive electrode tab group 250 is located at an end portion of the main body on a second side of the first electrode body 201 in the first direction (X direction). In this embodiment, the second side is the sealing plate 130 side.

[0090] The negative electrode tab group 220 and the positive electrode tab group 250 are formed to protrude from the center portion of the electrode body 200 toward the sealing plate 120 or the sealing plate 130 , respectively.

[0091] The current collector 400 includes a negative electrode current collector 400A and a positive electrode current collector 400B. The negative electrode current collector 400A and the positive electrode current collector 400B are each formed of a plate-shaped member. The electrode assembly 200 is electrically connected to the negative electrode terminal 301 and the positive electrode terminal 302 via the current collector 400 .

[0092] 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 assembly 220 and the negative electrode terminal 301. The negative electrode current collector 400A is made of a conductive material (more specifically, a metal), such as copper or a copper alloy. The details of the negative electrode current collector 400A will be described later.

[0093] The positive electrode current collector 400B is placed on the sealing plate 130 via a resin insulating member. The positive electrode current collector 400B is electrically connected to the positive electrode tab assembly 250 and the positive electrode terminal 302. The positive electrode current collector 400B is made of a conductive material (more specifically, a metal), such as aluminum or an aluminum alloy. The positive electrode tab assembly 250 can also be electrically connected to the sealing plate 130 directly or through the positive electrode current collector 400B. In this case, the sealing plate 130 also functions as the positive electrode terminal 302. The details of the positive electrode current collector 400B will be described later.

[0094] (Structure of Electrode Body 200 )

[0095] Figure 7 is a cross-sectional view of the negative electrode plate 210 ( Figure 8 VII-VII section view in Figure 1), Figure 8 It is a front view showing the negative electrode plate 210 .

[0096] like Figure 8 As shown, a plurality of negative electrode tabs 230 (first electrode tabs) formed of a negative electrode core 211 are provided at one end of the negative electrode plate 210 in the width direction. When stacking the negative electrode plates 210, the plurality of negative electrode tabs 230 are stacked to form a negative electrode tab group 220. The length of each negative electrode tab 230 in the plurality of negative electrode plates 210 in the protruding direction is appropriately adjusted in consideration of the connection state between the negative electrode tab group 220 and the negative electrode current collector 400A. The shape of the negative electrode tab 230 is not limited to Figure 7 The illustrated shape.

[0097] Figure 9 is a cross-sectional view of the positive electrode plate 240 ( Figure 10 IX-IX section view in Figure 1), Figure 10 It is a front view showing the positive electrode plate 240 .

[0098] like Figure 10As shown, at one end of the width direction of the formed positive electrode plate 240, a plurality of positive electrode tabs 260 (second electrode tabs) composed of a positive electrode core 241 are provided. 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 of each of the positive electrode tabs 260 in the plurality of positive electrode plates 240 in the protruding direction is appropriately adjusted in consideration of the connection state between the positive electrode tab group 250 and the positive electrode current collector 400B. The shape of the positive electrode tab 260 is not limited to Figure 10 The illustrated shape.

[0099] The positive electrode protection layer 243 is provided at the base of the positive electrode tab 260 . The positive electrode protection layer 243 does not necessarily need to be provided at the base of the positive electrode tab 260 .

[0100] In a typical example, the thickness of the negative electrode tab 230 (one sheet) is smaller than the thickness of the positive electrode tab 260 (one sheet). In this case, the thickness of the negative electrode tab group 220 is smaller than the thickness of the positive electrode tab group 250.

[0101] (Connection Structure between Electrode Body 200 and Current Collector 400)

[0102] Figure 11 yes Figure 1 XI-XI cross-sectional view of the secondary battery shown. Figure 11 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 include a positive electrode (second electrode) and a negative electrode (first electrode), respectively. The electrode body 200 may also be composed of three or more electrode bodies.

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

[0104] The first electrode body 201 includes a negative electrode tab assembly 220. A first end 205 of the negative electrode tab assembly 220 in the X direction is electrically connected to a current collector 410 (negative electrode current collector). The second electrode body 202 includes a negative electrode tab assembly 270. A third end 207 of the negative electrode tab assembly 270 in the X direction is electrically connected to another current collector 410 (negative electrode current collector).

[0105] The negative electrode tab assembly 220 has a bent portion 221 and a front end 222. The bent portion 221 is the portion of the negative electrode tab assembly 220 that is bent relative to the front end 222 on the side connected to the first electrode. The front end 222 is the end portion of the negative electrode tab assembly 220 located on the side opposite to the side connected to the first electrode.

[0106] The negative electrode tab assembly 270 includes a bent portion 271 and a front end portion 272. The bent portion 271 is the portion of the negative electrode tab assembly 270 that is bent relative to the front end portion 272 on the side connected to the first electrode. The front end portion 272 is the end portion of the negative electrode tab assembly 270 located on the side opposite to the side connected to the first electrode.

[0107] The negative electrode tab assembly 220 and the negative electrode tab assembly 270 are bent in opposite directions so that the front ends 222 and 272 approach each other. In this embodiment, the front ends 222 and 272 are separated, but the present invention is not limited to this structure and the front ends 222 and 272 may also contact each other.

[0108] The negative electrode current collector 400A electrically connects the negative electrode terminal 301 to the negative electrode tab assembly 220 and the negative electrode tab assembly 270. The negative electrode current collector 400A in this embodiment is connected to the negative electrode terminal 301 between the electrode assembly 200 and the sealing plate 120.

[0109] Negative electrode current collector 400A includes two components: current collector 410 and current collector 430. Current collector 410 is a plate-shaped component. Its longitudinal direction is in the Z direction, and its transverse direction is in the Y direction. Current collector 430 is a plate-shaped component. Its longitudinal direction is in the Z direction, and its transverse direction is 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 formed from separate components.

[0110] The negative electrode tab group 220 is described later (see Figure 14 ) The joint portion 411 is joined to one current collector 410. The negative electrode tab group 270 is described later (refer to Figure 14 ) The joint portion 411 is joined to the other current collector 410. The joint portion 411 can be formed, for example, by ultrasonic welding, resistance welding, laser welding, riveting, etc. In this embodiment, the negative electrode tab assembly 220 and the one current collector 410, and the negative electrode tab assembly 270 and the other current collector 410 are joined, for example, by ultrasonic welding.

[0111] The current collector 430 is joined to one current collector 410 and the other current collector 410 at a joint portion (not shown) located at an end 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 caulking and / or welding, for example.

[0112] The negative electrode terminal 301 is exposed outside the sealing plate 120. The negative electrode terminal 301 is connected to the plate-like member 303. It should be noted that the negative electrode terminal 301 preferably includes a region 301a composed of copper or a copper alloy and a region 301b composed of aluminum or an aluminum alloy, and the region 301a composed of copper or a copper alloy is connected to the current collector 430.

[0113] The plate-shaped member 303 is located outside the sealing plate 120. It is positioned along the sealing plate 120. The plate-shaped member 303 is electrically conductive. It is positioned to ensure a sufficient connection area with busbars, etc., that electrically connect the secondary battery 1 to adjacent secondary batteries. The connection between the negative electrode terminal 301 and the plate-shaped member 303 can be achieved, for example, by laser welding.

[0114] 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 .

[0115] However, the negative electrode terminal 301 may be electrically connected to the sealing plate 120 . In addition, the sealing plate 120 may also function as the negative electrode terminal 301 .

[0116] A separator 600 (first separator), described below, is placed between the sealing plate 120 and the main body of the electrode assembly 200 (excluding the negative electrode tab assembly 220). Separator 600 is made of an insulating resin member. The negative electrode tab assembly 220 passes through separator 600, thereby being protected by separator 600. It should be noted that a configuration without separator 600 (first separator) is also possible.

[0117] The detailed structure of the spacer 600 will be described later. The spacer 600 is provided with a convex portion 616 protruding in the Y direction. The convex portion 616 of the spacer 600 acts as a guide when bending the curved portions 221 and 271, thereby facilitating bending of the curved portions 221 and 271.

[0118] A resin insulating sheet 700 (electrode body holder) is placed between the electrode body 200 and the case body 110. The insulating sheet 700 can be made of, for example, a resin. More specifically, the insulating sheet 700 can be made of, for example, polypropylene (PP), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyimide (PI), or polyolefin (PO).

[0119] Figure 12 yes Figure 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 that on the negative electrode side in that the portion corresponding to one current collector 410 on the negative electrode side and the other current collectors 410 are formed of a single component.

[0120] The first electrode body 201 includes a positive electrode tab assembly 250. A second end 206 of the positive electrode tab assembly 250 in the X direction is electrically connected to a current collector 420 (positive electrode current collector). The second electrode body 202 includes a positive electrode tab assembly 280. A fourth end 208 of the positive electrode tab assembly 280 in the X direction is electrically connected to a current collector 420 (positive electrode current collector).

[0121] The positive electrode tab assembly 250 includes a bent portion 251 and a front end portion 252. The bent portion 251 is the portion of the positive electrode tab assembly 250 that is bent relative to the front end portion 252 on the side connected to the second electrode. The front end portion 252 is the end portion of the positive electrode tab assembly 250 located on the side opposite to the side connected to the second electrode.

[0122] The positive electrode tab assembly 280 includes a bent portion 281 and a front end portion 282. The bent portion 281 is the portion of the positive electrode tab assembly 280 that is bent relative to the front end portion 282 on the side connected to the second electrode. The front end portion 282 is the end portion of the positive electrode tab assembly 280 located on the side opposite to the side connected to the second electrode.

[0123] The positive electrode tab assembly 250 and the positive electrode tab assembly 280 are bent in opposite directions so that the front ends 252 and 282 approach each other. In this embodiment, the front ends 252 and 272 are separated, but the present invention is not limited to this structure and the front ends 252 and 282 may also contact each other.

[0124] The positive electrode current collector 400B electrically connects the positive electrode terminal 302 to the positive electrode tab group 250 and the positive electrode tab group 280. In this embodiment, the positive electrode current collector 400B is connected to the positive electrode terminal 302 between the electrode assembly 200 and the sealing plate 130.

[0125] The positive electrode current collector 400B includes a current collector 420 (first current collecting member) and a current collector 450 (second current collecting member). A plate 460 is interposed as an insulating member between the current collectors 420 (first current collecting member) and 450 (second current collecting member), but is electrically bonded to the plate at a position different from that shown in the cross section.

[0126] The current collector 420 is a plate-shaped member having a long side in the Z direction and a short side in the Y direction. The current collector 420 is formed as a single integral member.

[0127] The positive electrode tab group 250 and the positive electrode tab group 280 are connected at a joint 421 (see Figure 14 ) is joined to the current collector 420, which is composed of a single component. The joint 421 can be formed, for example, by ultrasonic welding, resistance welding, laser welding, riveting, or the like. In this embodiment, the positive electrode tab assembly 250 and the positive electrode tab assembly 280 are joined to the current collector 420, for example, by ultrasonic welding.

[0128] The current collector 440 is joined to the current collector 420 at a joining portion (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 caulking and / or welding, for example.

[0129] The positive electrode terminal 302 is provided so as to be exposed outside the sealing plate 130 and to reach the current collector 440 of the positive electrode current collector 400B provided on the inner surface side of the sealing plate 130 . The positive electrode terminal 302 is connected to the plate-shaped member 304 .

[0130] Plate-shaped member 304 is located outside sealing plate 130. Plate-shaped member 304 is positioned along sealing plate 130. Plate-shaped member 304 is electrically conductive. Plate-shaped member 304 is positioned to ensure sufficient connection area with busbars, etc., that electrically connect secondary battery 1 to adjacent secondary batteries. The connection between positive electrode terminal 302 and plate-shaped member 304 can be achieved, for example, by laser welding.

[0131] 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 .

[0132] However, the positive electrode terminal 302 may be electrically connected to the sealing plate 130 . In addition, the sealing plate 130 may also function as the positive electrode terminal 302 .

[0133] A spacer 600 (second spacer) is placed between the sealing plate 130 and the main body of the electrode body 200 (excluding the positive electrode tab assembly 250 and 280). The spacer 600 is made of an insulating resin member. The positive electrode tab assembly 250 and 280 passes through the interior of the spacer 600, thereby protecting the positive electrode tab assembly 250 and 280. It should be noted that a configuration without the spacer 600 (second spacer) is also possible.

[0134] The detailed structure of the spacer 600 will be described later. The spacer 600 is provided with a convex portion 616 protruding in the Y direction. The convex portion 616 of the spacer 600 acts as a guide when bending the curved portions 251 and 281, thereby facilitating bending of the curved portions 251 and 281.

[0135] The above-mentioned resin insulating sheet 700 (electrode body holder) is arranged between the electrode body 200 and the case body 110 .

[0136] (Manufacturing Process of Secondary Battery 1)

[0137] Hereinafter, a method for manufacturing the secondary battery of this embodiment will be described. Figure 13 This is a flowchart showing the method for manufacturing the secondary battery according to the first embodiment. Figure 14 This is a perspective view showing a state before two electrode bodies included in the secondary battery of Embodiment 1 are stacked. Figure 15 yes Figure 14 The electrode body and the current collector are shown in a cross-sectional view taken along the line XV-XV.

[0138] like Figure 13 As shown, in the secondary battery manufacturing method of this embodiment, first, a first electrode body 201 and a second electrode body 202 are fabricated (step S1). 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 preferably each partially cut off at the front end so that the front ends are the same length when bundled.

[0139] like Figures 13 to 15 As shown, after fabricating the first electrode body 201 and the second electrode body 202, the negative electrode tab assembly 220 is joined to one current collector 410 (step S2). The negative electrode tab assembly 220 is joined to one current collector 410 at a joining portion 411. Next, the negative electrode tab assembly 270 is joined to the other current collector 410 (step S3). The negative electrode tab assembly 270 is joined to the other current collector 410 at a joining portion 411.

[0140] Next, the first electrode body 201, the current collector 420, and the second electrode body 202 are arranged in this order in the first direction (DR1). The positive electrode tab assembly 250 is placed on one side of the current collector 420 in the first direction (DR1). With the positive electrode tab assembly 280 placed on the other side of the current collector 420 in the first direction (DR1), the positive electrode tab assembly 250 and the positive electrode tab assembly 280 are joined to the current collector 420 (step S4). The positive electrode tab assembly 250 and the positive electrode tab assembly 280 are joined to the current collector 420 at the joining portion 421.

[0141] In the height direction of the first electrode body 201 and the second electrode body 202, one current collector 410, the other current collectors 410, and the current collector 420 are arranged to one side relative to the center of the first electrode body 201 and the second electrode body 202. This allows the current collectors to be shorter and more compact.

[0142] The current collector 410, the other current collectors 410, and the current collector 420 are not limited to this structure. The current collectors 410 and 420 may be arranged 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 arranged 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, respectively, corresponding to the current collectors 410 and 420.

[0143] 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 order described above and may be changed. The steps of joining the current collector 410 to the first electrode body 201 and the second electrode body 202, respectively, are preferably performed before the step of superimposing the first electrode body 201 and the second electrode body 202, which will be described later, and are preferably performed before the step of joining the current collector 420 to the first electrode body 201 and the second electrode body 202.

[0144] Next, after the positive electrode tab group 250 and the positive electrode tab group 280 are joined to the current collector 420, the first electrode body 201 and the second electrode body 202 are connected in the thickness direction (in the direction of the thickness of the first electrode body 201 and the second electrode body 202). Figure 14 as well as Figure 15 The positive electrode tab group 250 and the positive electrode tab group 280 are bent in a direction perpendicular to the DR1 direction to overlap the first electrode body 201 and the second electrode body 202 (step S5). That is, the first electrode body 201 and the second electrode body 202 are brought together.

[0145] "Overlaying the first and second electrode bodies" means that the first and second electrode bodies can be directly overlapped, or another component can be placed between the first and second electrode bodies. Furthermore, the first and second electrode bodies may be secured by tape or the like, or not. Furthermore, the first electrode body, current collector, and second electrode body do not need to be arranged in a straight line in the first direction (DR1 direction). The first electrode body or the second electrode body may be tilted relative to the current collector relative to the first direction (DR1 direction).

[0146] The positive electrode tab group 250 and the positive electrode tab group 280 are bent so that their front ends face each other. In addition, the negative electrode tab group 220 and the negative electrode tab group 270 are also bent so that their front ends face each other.

[0147] Figure 13 as well as Figure 16 : is a perspective view showing a state where a retainer and a spacer are installed on an electrode body. Figure 16 As shown, next, the separator 600 and the insulating sheet 700 are assembled to the electrode body 200 (step S6 ).

[0148] The insulating sheet 700 does not necessarily need to cover the entire surface of the electrode body 200. The insulating sheet 700 preferably covers at least 50% of the outer surface of the electrode body, and more preferably at least 70%. The insulating sheet 700 preferably covers the entirety of four of the six surfaces of the generally rectangular (flat) electrode body 200, excluding at least two surfaces each having the negative electrode tab assembly 220 and the positive electrode tab assembly 250 formed thereon. The specific form of the insulating sheet 700 will be described later.

[0149] Figure 17 It is a perspective view showing a state where a sealing plate 120 is attached to the current collector on the negative electrode side. Figure 18 yes Figure 17 The electrode body and the current collector are shown in cross-sectional view taken along line XVIII-XVIII. Figure 19 as well as Figure 20 1 and 2 are first and second perspective views showing the configuration of the spacer 600. Figure 21 700 is a side view showing the positional relationship between the spacer 600 and the insulating sheet 700. Figure 18 , the housing body 110 is omitted.

[0150] like Figure 19 as well as Figure 20 As shown, spacer 600 is made of an insulating resin member. Spacer 600 includes a first member 612 and a second member 614, each surrounded on three sides by side walls, and a connecting wall 611 connecting one side wall of each of the first and second members 612, 614. Inside connecting wall 611, a protrusion 616 is provided, extending (in the Z direction) between first and second members 612, 614.

[0151] The first component 612 includes a first plate portion 617 that connects three walls. The first plate portion 617 is provided with a plurality of elliptical first through-holes 617s. The shape and number of the first through-holes 617s can be selected as appropriate and are not limited to the shape and number shown in the figure. A first protrusion 612p that protrudes outward is provided in the region of the first component 612 opposite the first plate portion 617 (on the side opposite the electrode body).

[0152] The second component 614 includes a second plate portion 618, which connects the three walls. Second plate portion 618 is provided with a plurality of elliptical second through-holes 618s. The shape and number of second through-holes 618s can be selected as appropriate and are not limited to the shape and number shown in the figure. A second protrusion 614p, projecting outward, is provided in the region of the second component 614 opposite the second plate portion 618 (on the side opposite the electrode body).

[0153] The first plate portion 617 and the second plate portion 618 are located on the end face side of the electrode body. The plate portion can abut against the end face of the electrode body. Even if it does not abut, the shortest distance to the electrode body is preferably within 2 mm, more preferably within 1 mm. In addition, by providing the first through hole 617s and the second through hole 618s, Figure 1 When the secondary battery 1 shown is placed with the Z direction facing upward (the direction in which the openings 113 (first opening) and the openings 114 (second opening) at both ends of the shell body 110 are arranged left and right), even if the electrolyte is squeezed out of the electrode body during charging (usually due to expansion of the electrode plates) and flows to the outside of the portion, it is easy to return to the electrode body during discharge (usually due to contraction of the electrode plates).

[0154] The outer dimensions of the separator 600 (the first separator and the second separator) are preferably smaller than those of the electrode body 200. Since the electrode body 200 is wound around the insulating sheet 700, the separator 600 is also wound around the insulating sheet 700. Therefore, by making the outer dimensions of the separator 600 smaller than those of the electrode body 200, the insertion of the electrode body 200 into the case body 110 can be improved.

[0155] like Figure 21 As shown, when the electrode body 200 is covered with the insulating sheet 700, the separator 600 is preferably also covered by the insulating sheet 700. In this case, the negative electrode tab group and the positive electrode tab group pass through the interior of the separator 600, thereby protecting the negative electrode tab group and the positive electrode tab group. In addition, the separator 600 is also covered by the insulating sheet 700, thereby further protecting the negative electrode tab group and the positive electrode tab group. It should be noted that the first protrusion 612p and the second protrusion 614p provided on the separator 600 are preferably exposed from the insulating sheet 700.

[0156] like Figure 13 、 Figure 17 as well as Figure 18As shown, after the negative electrode tab assembly 220 is joined to the current collector 410, the negative electrode tab assembly 270 is joined to the current collector 430, and the first electrode body 201 and the second electrode body 202 are superimposed, 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). It should be noted that step S7 can also be performed before step S6.

[0157] Specifically, the negative electrode tab group 220 and the negative electrode tab group 270 are bent so that the front end portions 222 and 272 face each other.

[0158] The negative electrode terminal 301 and current collector 430 are attached to the sealing plate 120 via an insulating member. The current collector 430 is brought into contact with one current collector 410 and the other current collector 410 in the X direction. It should be noted that the plate-like member 303 can be connected to the negative electrode terminal 301 at any time. The current collector 430 is joined to one current collector 410 and the other current collector 410 by laser welding between the sealing plate 120 and the insulating sheet 700.

[0159] Figure 22 : is a perspective view showing the state where the electrode body is inserted into the shell body. Figure 13 as well as Figure 22 As shown, after the first electrode body 201 and the second electrode body 202 are stacked, the first electrode body 201 and the second electrode body 202 are inserted into the case body 110 through the opening 113, with the current collector 420 side facing forward (step S8). At this time, the first electrode body 201 and the second electrode body 202 are inserted into the case body 110 in a state where the negative electrode active material layer 212 protrudes toward the negative electrode tab 230 relative to the positive electrode active material layer 242 at the negative electrode tab 230 side of the first electrode body 201 and the second electrode body 202.

[0160] The negative electrode tab group 220 and the negative electrode tab group 270 are bent by bringing the sealing plate 120 close to the main body of the electrode body 200 (the first electrode body 201 and the second electrode body 202). It should be noted that it is preferable to bring the sealing plate 120 close to the main body of the electrode body 200 disposed in the case body 110. Figure 11 As shown, the negative electrode tab group 220 and the negative electrode tab group 270 are bent along the shape of the separator 600 so that the folded-back portions of the bent portions 221 and 271 approach the case body 110 in the Y direction.

[0161] After the sealing plate 120 is brought into contact with the housing body 110, the sealing plate 120 is temporarily joined to the housing body 110. The temporary joining partially joins the sealing plate 120 to the opening 113 of the housing body 110. Thus, the sealing plate 120 is positioned relative to the housing body 110.

[0162] When the electrode body 200 is inserted into the case body 110, the electrode body 200 can be pulled from the current collector 420 side or pressed from the current collectors 410 and 430. When the electrode body 200 is pressed from the current collectors 410 and 430 sides, the negative electrode tab group 220 and the negative electrode tab group 270 can be bent simultaneously.

[0163] Reference Figure 23 , is a perspective view showing a state where a sealing plate 130 is attached to the current collector on the positive electrode side. Figure 24 yes Figure 23 The electrode body and the collector are shown in the XXIII-XXIII cross-sectional view. Figure 24 , the housing body 110 is omitted.

[0164] like Figure 13 、 Figure 22 as well as Figure 23 As shown, after the first electrode body 201 and the second electrode body 202 are inserted into the case body 110 , the current collector 420 and the positive electrode terminal 302 are electrically connected (step S9 ).

[0165] 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 plate-shaped member 304 can be connected to the positive electrode terminal 302 at any time.

[0166] like Figure 24 As shown, the positive electrode tab group 250 and the positive electrode tab group 280 connected to the current collector 420 are bent so that the front end portions 252 and 282 face each other. Figure 24 In the state shown, the sealing plate 130 is brought into contact with the housing body 110. At this time, the positive electrode tab group 250 and the positive electrode tab group 280 are bent by bringing the sealing plate 130 and the main body of the electrode body 200 close to each other. Figure 12 As shown, 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 bent portions 251 and 281 approach the case body 110 in the Y direction.

[0167] After the sealing plate 130 is brought into contact with the housing body 110, the sealing plate 130 is temporarily welded to the housing body 110. The temporary welding partially joins the sealing plate 130 to the opening 114 of the housing body 110. Thus, the sealing plate 130 is positioned relative to the housing body 110.

[0168] Figure 25 1 is a perspective view showing the structure of the secondary battery 1. Figure 13 as well as Figure 25 As shown, sealing plates 120 and 130 are then bonded to case body 110 (step S10 ). Sealing plate 120 seals opening 113 of case body 110 , while sealing plate 130 seals opening 114 of case body 110 . Thus, first electrode body 201 and second electrode body 202 are housed in case 100 .

[0169] After the above steps, a leak test and other inspections are performed (step S11). After the leak test, the secondary battery 1 is dried to remove moisture from the housing 100. Then, the electrolyte is injected into the housing 100 through the injection hole 134. When injecting the electrolyte, the housing 100 is tilted with the sealing plate 130 at the top and the sealing plate 120 at the bottom, and the electrolyte is injected into the housing 100 through the injection hole 134 of the sealing plate 130. After that, exhaust charging is performed. During exhaust charging, the injection hole 134 can also be temporarily sealed. After that, the injection hole 134 is sealed, and the secondary battery 1 is completed.

[0170] The order of the electrode assembly 200 insertion step and the current collector connection step is not limited to the example described above. For example, after only partially inserting the electrode assembly 200 into the case body 110 (first step), with the end of the negative electrode active material layer 212 (second electrode active material layer) on the opening 113 side positioned outside the case body 110, the negative electrode terminal 301 (first electrode terminal) provided on the sealing plate 120 (first sealing plate) is electrically connected to the negative electrode tab group 220 and 270 (first electrode tabs). The electrode assembly 200 is then inserted into the case body 110 until the end of the negative electrode active material layer 212 on the opening 113 side is positioned inside the case body 110 (second step). In other words, the negative electrode terminal 301 can be electrically connected to the electrode assembly 200 during the insertion step of the electrode assembly 200 into the case body 110.

[0171] In this embodiment, by providing negative tab group 220 and positive tab group 250 in first electrode body 201 and negative tab group 270 and positive tab group 280 in second electrode body 202 , it is possible to achieve a structure in which separate electrode tabs are provided in first electrode body 201 and second electrode body 202 .

[0172] With this structure, the electrode tab can be shortened compared to a case where the first electrode body 201 and the second electrode body 202 form a single electrode tab and the electrode tab is bent.

[0173] As a result, the volume occupied by the electrode tab can be reduced, thereby improving the energy density of secondary battery 1. Furthermore, the structure in which separate electrode tabs are provided in first electrode body 201 and second electrode body 202 is easier to bend than a structure in which the first electrode body 201 and second electrode body 202 form a single integrated electrode tab. This facilitates the joining of the electrode tab to the current collector, allowing for stable secondary battery manufacturing. In particular, the stable manufacturing of secondary battery 1 improves the reliability of the connection between the electrode tab and the current collector.

[0174] (Specific form of insulating sheet)

[0175] Reference Figures 26 to 30 , the specific form of the insulating sheet 700 will be described. In some drawings, the shape and cross-sectional shape of the secondary battery 1 are schematically illustrated without considering actual dimensional relationships in order to facilitate understanding of the structure. Figure 26 yes Figure 25 XXVI-XXVI cross-sectional view of the secondary battery shown, Figure 27 yes Figure 25 XXVII-XXVII cross-sectional view of the secondary battery shown, Figure 28 is an expanded view of the insulating sheet 700. Figure 29 is with Figure 25 The reference cross-sectional view corresponding to the XXVI-XXVI section of the secondary battery shown, Figure 30 is with Figure 25 This is a reference cross-sectional view corresponding to the section XXVI-XXVI of the secondary battery shown.

[0176] like Figure 26 as well as Figure 27 As shown, the insulating sheet 700 is provided inside the case body 110 so as to cover the outer surfaces of the electrode bodies 200 (the first electrode body 201 and the second electrode body 202). The insulating sheet 700 is preferably formed from a single sheet, and a single sheet of insulating sheet 700 can be wound around the electrode body 200. As described later, the overlapping region OR is formed by overlapping the first region R1 and the second region R2 of the insulating sheet 700.

[0177] like Figure 28As shown, the insulating sheet 700 is a rectangular sheet when unfolded. The insulating sheet 700 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 the electrode body 200. The first region R1 of the insulating sheet 700 is located near one end of the sheet, while the second region R2 is located near the other end of the sheet.

[0178] In the width direction (X direction) of the electrode body 200, the overlapping region OR includes a central region CR and end regions PR located on both sides of the central region CR. A non-overlapping region is provided in the central region CR to reduce the area of the overlapping region OR. Here, in this embodiment, the central region CR of the insulating sheet 700 is set to approximately 80% in the central portion in the horizontal direction (the width direction of the electrode body 200), and the remaining approximately 10% on both sides is set to the end regions PR.

[0179] The non-overlapping area that reduces the area of the overlapping area OR refers to the following area: compared with the state in which the shape of the second area R2 in the lateral direction does not change in the central area CR and the end area PR, when the non-overlapping area is provided, the shape of the second area R2 is changed in the central area CR, and the area of the overlapping area OR is reduced.

[0180] In the second region R2 of the insulating sheet 700 of this embodiment, the central region CR includes recessed portions 710s at the circumferential end sides as non-overlapping regions. These recessed portions 710s are recessed inward relative to the end sides of the end regions. Various configurations of the recessed portions 710s are possible, but in the central region CR, the ratio of the non-overlapping region to the overlapped area without the recessed portions 710s can be 20% or greater.

[0181] The width of the recess 710s is preferably about 30% or more of the overall width of the main body of the electrode body 200, and more preferably 50% or more. The length of the main body of the electrode body 200 refers to the length excluding the length of the negative electrode tab group and the positive electrode tab group provided on both sides of the electrode body 200. It should be noted that the width of the recess 710s is the width of the largest part. For example, Figure 28 As shown, the width of the concave portion 710s is toward the front end of the second region R2 (at Figure 28 In the case of a shape extending from the top end in the middle, the front end of the second region R2 in the recess 710s is set to be the top end in the middle. Figure 28 The width of the position corresponding to the top (center is the top).

[0182] To facilitate winding onto the electrode assembly 200, the insulating sheet 700 preferably has fold lines (creases) L1 at the boundaries of each region. Providing inwardly recessed first cutout regions 711 at both ends of the widthwise direction of the fold lines (creases) L1 facilitates winding onto the electrode assembly 200. While the shape of the first cutout regions 711 is shown as a semicircle, other shapes such as a trapezoid, rectangle, or triangle are also possible.

[0183] To facilitate connection to the spacer 600 (described later), inwardly recessed second cutouts 712 may be provided at both ends of the first region R1 of the insulating sheet 700 in the width direction. While the second cutouts 712 are shown as rectangular, they may also be semicircular, trapezoidal, rectangular, triangular, or other shapes. Furthermore, rather than being open on one side as shown, they may be through-holes.

[0184] The angle (α) formed between the side edges 710s1 at both ends of the recess 710s and the end edge 710t of the end region PR may be 100 degrees or greater. This can prevent the insulating sheet 700 from being caught when the electrode assembly 200 wound with the insulating sheet 700 is inserted into the case body 110 .

[0185] As mentioned above, insulating sheet 700 can be made of, for example, a resin. More specifically, insulating sheet 700 can be made of, for example, polypropylene (PP), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyimide (PI), or polyolefin (PO). Insulating sheet 700 is preferably thicker than separator 800 (5 μm to 20 μm).

[0186] Refer again Figure 26 as well as Figure 27 The electrode assembly 200 includes a pair of first surfaces 21 and a third surface 23 corresponding to the height direction (Z direction) of the secondary battery 1, and a pair of second surfaces 22 and a fourth surface 24 corresponding to the thickness direction (Y direction) of the secondary battery. It should be noted that 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.

[0187] The electrode body 200 can be configured as a stacked electrode body including a plurality of positive plates and a plurality of negative plates. In this case, the first surface 21 becomes a surface on one side where the end faces of the positive plates and the end faces of the negative plates are arranged. However, the end faces of the positive plates or the end faces of the negative plates can also be covered by a separator. In addition, the positions of the end faces of the positive plates and the end faces of the negative plates can also be offset. It should be noted that the separator can be a plurality of rectangular separators, or a separator obtained by folding a strip-shaped separator in a zigzag manner, or other forms.

[0188] When the insulating sheet 700 is wound 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, with an overlapping region OR where the second region R2 overlaps the first region R1. It should be noted that the boundaries between adjacent regions in the first through fifth regions R1, R5, form folds.

[0189] The front end of the second region R2 may be separated from the first region R1 and the bent portion of the fourth region R4 (the outer surface of the fourth region R4) by a distance H1 in the figure. The distance H1 may be at least 5%, preferably at least 10%, of the thickness of the electrode body 200.

[0190] When the insulating sheet 700 having the above-described configuration is wound around the electrode body 200, as shown in FIG. Figure 26 As shown, the winding is performed such that the first region R1 is located on the side in contact with the separator 600 and the second region R2 is located above the first region R1.

[0191] In the area where the spacers 600 (first and second spacers) are located on both sides, the insulating sheet 700 is connected to the spacers 600 (first and second spacers) using the second cutouts 712 provided in the first area R1. The insulating sheet 700 is connected to the spacers 600 using various connection methods, such as heat welding, ultrasonic welding, tape application, adhesive application, fitting, and hooking.

[0192] like Figure 26 As shown, the connection portion 740 is preferably provided by connecting the area facing the second cutout 712 in the second region R2 to the spacer 600 through the second cutout 712. It should be noted that, as described above, the second cutout 712 may be replaced by a through hole or the like.

[0193] When the insulating sheet 700 is connected to the spacer 600, the second region R2 is directly fixed to the spacer 600 by utilizing the second notch 712 provided in the first region R1 while the second region R2 presses the first region R1. As a result, the insulating sheet 700 can be stably and easily fixed to the spacer 600.

[0194] In the case of a structure in which the spacer 600 is not provided, the first region R1 and the second region R2 are connected using the above-described connection method in the regions at both ends of the second cutout 712 .

[0195] When the insulating sheet 700 having the above-described configuration is wound around the electrode body 200, as shown in FIG. Figures 26 to 29As shown, the ratio 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 body 200 is preferably greater than the ratio of the overlapping portion between the first region R1 and the second region R2 in the region corresponding to the end region of the first surface 21 of the electrode body 200. Thus, by providing a certain degree of overlapping portion between the first region R1 and the second region R2, the positional relationship between the insulating sheet 700 and the electrode body 200 can be stabilized, and the permeability of the electrolyte into the central region of the electrode body 200 can be improved. It should be noted that the present disclosure is particularly effective in high-capacity batteries (e.g., batteries with a capacity of 50 Ah or more).

[0196] When the spacer 600 is provided, the positional relationship between the insulating sheet 700 and the electrode body 200 can be more effectively stabilized. When the insulating sheet 700 having the above-described configuration is wound around the electrode body 200, in the overlapping portion between the first region R1 and the second region R2, as shown in FIG. Figure 26 As shown, in the end region PR, the overlapping area ratio of the first region R1 and the second region R2 is ensured to be large, and in the recess 710s, the overlapping area ratio of the first region R1 and the second region R2 is made smaller than that in the end region PR.

[0197] As a result, the winding area of the insulating sheet 700 around the spacer 600 can be ensured in the end region PR, and the winding state of the insulating sheet 700 around the spacer 600 can be stabilized. On the other hand, the provision of the recess 710s reduces the overlapping area and creates a gap between the first region R1 and the second region R2.

[0198] By reducing the overlapping state of the overlapping area, the electrolyte ( Figure 26 The path (arrow R10) of the electrode body 200 is shortened, and the electrolyte can easily enter the interior. As a result, it is possible to prevent the electrolyte from being blocked. For example, Figure 29 As shown, if the overlapping length of the first region R1 and the second region R2 becomes longer, the electrolyte ( Figure 30 The path (arrow R10 in FIG. 1 ) of the electrolyte entering the electrode body 200 becomes longer, and the entry of the electrolyte is easily hindered.

[0199] Thus, the structure of the secondary battery 1 in the embodiment can suppress direct contact between the electrode body 200 and the case body 110, and can also suppress the obstruction of the electrolyte from penetrating into and entering and exiting the electrode body 200. As a result, a secondary battery 1 can be provided that has improved electrolyte permeability into the high-capacity, high-density electrode body 200.

[0200] like Figure 5As shown, the case body 110 is provided with a gas discharge valve 150, but this surface may be disposed opposite the first surface 21 of the electrode body 200. The gas discharge valve 150 ruptures when the internal pressure of the case body 110 exceeds a predetermined value, discharging the gas within the case body 110 to the outside of the case body 110. Therefore, when the overlapping area between the first region R1 and the second region R2 of the insulating sheet 700 is minimized, the gas generated from the electrode body 200 can be more efficiently discharged to the outside of the case body 110.

[0201] For example, refer to Figure 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 assembly 200 to be efficiently discharged to the outside.

[0202] The above-mentioned insulating sheet 700 adopts a structure in which a recess 710s is provided in the second region R2 on the outside. Figure 30 As shown, the same effect can be obtained by providing the recess 710s in the inner first region R1.

[0203] (Specific Form of Recess 710s)

[0204] Next, refer to Figure 31 , a specific form of the recessed portion 710s constituting the non-overlapping region provided in the second region R2 will be described. Figure 31 Indicates the area of each region when viewed from the first surface 21 side of the electrode body 200 (when viewed from a direction perpendicular to the first surface 21), [1] shows the area (Sh2) of the second region R2 of the insulating sheet 700, [2] shows the area (Ss1) of the spacer 600 (first spacer), the area (Se1) of the first surface 21 of the electrode body 200, and the area (Ss2) of the spacer 600 (second spacer), [3] shows the area (Sh1) of the first region R1 of the insulating sheet 700, and [4] shows the area (So1) of the region where the first region R1 and the second region R2 of the insulating sheet 700 overlap. It should be noted that the area of the electrode body 200 excludes the areas of the positive electrode tab group and the negative electrode tab group. Figure 32 , the illustration of the housing body 110 is omitted.

[0205] In this way, when the area of each region is specified, when the ratio of [the area of the region where the spacer 600 (first spacer) overlaps with the first region R1 and the second region R2] / [(the area of the spacer 600 (first spacer) (Ss1)] is set to X1, and the ratio of [the area of the region that does not overlap with the spacer 600 (first spacer) in the electrode body 200, the first region R1 and the second region R2 overlap] / [(the area of the region that does not overlap with the spacer 600 (first spacer) in the electrode body 200 (Se1)] is set to Y1, X1 can be set to be larger than Y1. The same applies when the spacer 600 (first spacer) is replaced by the spacer 600 (second spacer).

[0206] Thus, the ratio of the overlapping area between the first region R1 and the second region R2 in the region overlapping with the separator 600 is preferably greater than the ratio of the overlapping area between the first region R1 and the second region R2 in the region overlapping with the electrode body 200 .

[0207] Specifically, X1 is preferably 0.5 or more, more preferably 0.6 or more, and even more preferably 0.7 or more. In addition, Y1 is preferably less than 0.5, more preferably 0.4 or less, and even more preferably 0.3 or less. It should be noted that Y1 is, for example, preferably 0.03 or more, and even more preferably 0.05 or more.

[0208] It should be noted that only one of the first spacer side and the second spacer side satisfies the above relationship. However, it is preferred that both the first spacer side and the second spacer side satisfy the above relationship. It should be noted that both the first spacer side and the second spacer side are not required structures, and only one of them may be provided.

[0209] Here, the above values are for the case where the spacers 600 (first spacer, second spacer) are provided. Figure 32 In the following, a case where optimization of the area ( So1 ) of the overlapping region between the first region R1 and the second region R2 is studied regardless of the presence or absence of the spacer 600 is described. Figure 32 2 is a diagram showing the central region CR and the end region when viewed from the first surface 21 side of the electrode body 200. Figure 32 , the illustration of the housing body 110 is omitted.

[0210] Reference Figure 32 Regardless of the presence or absence of the spacer 600, when observed from the first surface 21 side of the electrode body 200, the central region CR refers to the area between negative 25% and positive 25% (negative is the left direction in the figure, positive is the right direction in the figure) from the center line (CL) of the insulating sheet 700 (electrode body 200), and the end region refers to the area 10% from the end of the insulating sheet 700.

[0211] In the above case, when the ratio of [the area of the overlapping portion of the first region R1 and the second region R2 in the end region (the region 10% from the end)] / [the area of the end region (the region 10% from the end)] is set to X2, and the ratio of [the area of the overlapping portion of the first region R1 and the second region R2 in the central region CR (the region between -25% and +25% from the center)] / [the area of the central region CR (the region between -25% and +25% from the center)] is set to Y2, X2 can be set to be larger than Y2.

[0212] Specifically, X2 is preferably 0.5 or more, more preferably 0.6 or more, and even more preferably 0.7 or more. In addition, Y2 is preferably less than 0.5, more preferably 0.4 or less, and even more preferably 0.3 or less. It should be noted that Y2 is, for example, preferably 0.03 or more, and even more preferably 0.05 or more.

[0213] Reference Figure 33 A case where the recessed portion 710 s is provided in the first region R1 in the second region R2 located outside and the first region R1 located inside of the insulating sheet 700 facing the first surface 21 of the electrode body 200 will be described. Figure 33 Equivalent to Figure 30 A partially enlarged view of the first surface 21 side of the electrode body 200 is shown.

[0214] When recessed portions 710s are provided on the inner side, electrolyte may accumulate in the gap S1 formed between the insulating sheet 700 and the case body 110. Therefore, when the thickness of the electrode body 200 is set to 100, the length L1 of the second region R2 of the electrode body 200 located on the case body 110 side in the thickness direction is preferably 90 or greater. On the other hand, when the thickness of the electrode body 200 is set to 100, the length L2 of the first region R1 located on the electrode body 200 side is preferably 20 or less to ensure internal space for electrolyte flow and to allow for the injection of a large amount of electrolyte at a time.

[0215] (Embodiment 2: Insulating Sheet 700A)

[0216] Reference Figure 34 As long as a region having the same function as the non-overlapping region provided in the central region CR of the insulating sheet 700 to reduce the overlapping area of the overlapping region is provided, the shape of the recessed portion 710s is not limited. Figure 34 It is a development view showing the state of the insulating sheet 700A according to the second embodiment.

[0217] In this insulating sheet 700A, multiple through-holes 720 are provided in the central region CR instead of the recessed portions 710s that constitute the non-overlapping region. The shape of the through-holes 720 is not particularly limited and can be various shapes such as circular, elliptical, and rectangular. It should be noted that the through-holes 720 only need to be formed in at least one of the first region R1 or the second region R2.

[0218] In this manner, even when a plurality of through holes 720 are used as the non-overlapping region, it is possible to achieve the same operational effects as those of the insulating sheet 700 in the first embodiment.

[0219] (Embodiment 3: Insulating Sheet 700B)

[0220] Reference Figure 35 , other forms of insulating sheets are described. Figure 35 It is a development view showing the state of an insulating sheet 700B according to the third embodiment.

[0221] exist Figure 28 In the illustrated insulating sheet 700 , the recess 710 s is provided throughout the entire central region CR. However, in the insulating sheet 700B of the present embodiment, the recess 710 s is provided in a portion of the central region CR, not in the entire central region CR.

[0222] Even with the form of the recessed portion 710s, the same operational effects as those of the insulating sheet 700 in the first embodiment can be achieved.

[0223] (Embodiment 4: Insulating Sheet 700C)

[0224] Reference Figure 36 , other forms of insulating sheets are described. Figure 36 It is a development view showing the state of an insulating sheet 700C according to the fourth embodiment.

[0225] In this embodiment, the recessed portion 710s provided in the central region CR is divided into two locations. However, the recessed portion 710s is not limited to two locations, and may be divided into three or more locations.

[0226] Even when the recessed portion 710s is divided into a plurality of parts in this manner, the same operational effects as those of the insulating sheet 700 in the first embodiment can be achieved.

[0227] While the embodiments of the present invention have been described, the embodiments disclosed herein are to be construed in all respects as illustrative and not restrictive. The scope of the present invention is indicated by the claims, and is intended to encompass all modifications within the meaning and scope of the claims and equivalents thereof.

Claims

1. A secondary battery, wherein: The secondary battery comprises: an electrode body comprising a first electrode and a second electrode having a polarity different from that of the first electrode; a battery housing, the battery housing housing the electrode body; a first electrode tab group, the first electrode tab group being electrically connected to the first electrode and disposed at one end of the electrode body; a second electrode tab group, the second electrode tab group being electrically connected to the second electrode and disposed at the other end of the electrode body; and 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 area and the second area cover the first surface, An overlapping area is provided in which the second area overlaps the first area, 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. A non-overlapping region is provided in the central region to reduce the overlapping area of the overlapping region.

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

3. The secondary battery according to claim 1, wherein At least one of the first region and the second region has a concave portion as the non-overlapping region at an end side of the central region in the circumferential direction, which is recessed inward from the end side of the end region.

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

5. The secondary battery according to claim 3, wherein An angle formed by side edges at both ends of the recess and an end edge of the end region is greater than or equal to 100 degrees.

6. The secondary battery according to claim 1, wherein The secondary battery further includes: a first separator, the first separator being disposed on an end surface of the electrode body where the first electrode tab group is provided; and a second separator, the second separator being arranged on an end surface of the electrode body where the second electrode tab group is provided; On the side where the first electrode tab group is provided, the insulating sheet is connected to the first spacer. The insulating sheet is connected to the second separator on a side where the second electrode tab group is provided.

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

8. The secondary battery according to claim 6, wherein In order to connect the insulating sheet to the first spacer, The first region has an opening or a cutout, The second region is connected to the first spacer in a region facing the opening or the cutout.

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

10. The secondary battery according to claim 1, 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 bending portion is provided between the first region and the fourth region, The front end of the second region is located away from the bent portion.

11. The secondary battery according to claim 1, wherein A gas discharge valve is provided in the battery housing. The surface of the battery case on which the gas exhaust valve is provided faces the first surface.

12. The secondary battery according to claim 1, wherein The battery housing comprises: a housing body having a first opening at one end and a second opening at the other end; a first sealing plate, the first sealing plate sealing the first opening and being welded to the housing body; and a second sealing plate, the second sealing plate sealing the second opening and being welded to the shell body; The first electrode tab group is arranged at the end portion of the electrode body on the first opening side. The second electrode tab group is arranged at an end portion of the electrode body on the second opening side.

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