Secondary battery

Abstract

To provide a secondary battery having higher volume energy density and higher reliability.SOLUTION: A secondary battery includes a current collector 420 and a current collector 440. The current collector 420 includes a first region R1 and a second region R2, and the current collector 440 includes a third region R3 and a fourth region R4. A positive electrode tab is connected to the first region R1, the second region R2 and the fourth region R4 are joined to each other, and a first insulating member 460 is disposed between the first region R1 and the third region R3. According to this secondary battery, a secondary battery having a higher volume energy density and higher reliability can be provided.SELECTED DRAWING: Figure 27

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] There is a demand for secondary batteries with higher volumetric energy density and higher reliability, and there is room for further improvement in the structure and assembly method of the current collector.

[0005] An object of the present technology is to provide a secondary battery with higher volumetric energy density and higher reliability. [Means for solving the problem]

[0006] The present technology provides the following secondary battery and method for manufacturing the same. [1] A secondary battery comprising: an electrode assembly including a first electrode and a second electrode having a polarity opposite to that of the first electrode; a case body that houses the electrode assembly and has a first opening; a first sealing plate that seals the first opening; a first electrode tab electrically connected to the first electrode; a first current collecting member electrically connected to the first electrode tab; a second current collecting member joined to the first current collecting member; and a first electrode terminal electrically connected to the second current collecting member and provided on the first sealing plate, wherein the first current collecting member includes a first region and a second region, and the second current collecting member includes a third region and a fourth region, the first electrode tab is connected to the first region, the second region is joined to the fourth region, and a first insulating member is disposed between the first region and the third region.

[0007] [2] The secondary battery described in [1], wherein the first insulating member has a protruding portion that protrudes toward the first sealing plate, and the protruding portion abuts against the first sealing plate or another insulating member arranged on the first sealing plate.

[0008] [3] The secondary battery described in [2], wherein a second insulating member is disposed between the first sealing plate and the second current collecting member, the other insulating member is the second insulating member, and the protrusion abuts against the second insulating member.

[0009] [4] The secondary battery according to [3], wherein the first insulating member is connected and fixed to the second insulating member.

[0010] [5] The secondary battery according to any one of [1] to [4], wherein the case body has a second opening at a position opposite the first opening, the second opening is sealed by a second sealing plate, the second sealing plate is provided with a second electrode terminal electrically connected to the second electrode, and the electrode body has the first electrode tab provided at an end on the first sealing plate side and a second electrode tab electrically connected to the second electrode at an end on the second sealing plate side.

[0011] [6] The secondary battery according to any one of [1] to [5], further comprising a first contact portion where the second region and the fourth region contact each other, and a joint portion where the first current collecting member and the second current collecting member are joined at an end of the first contact portion.

[0012] [7] The secondary battery according to any one of [1] to [6], wherein, in a direction perpendicular to the first sealing plate, the surface of the second region facing the first sealing plate is located closer to the first sealing plate than the surface of the first region facing the first sealing plate.

[0013] [8] The secondary battery according to any one of [1] to [7], wherein the first insulating member includes a plate portion, the plate portion has a recess, and at least a portion of the first current collecting member or the second current collecting member is disposed within the recess.

[0014] [9] The secondary battery according to any one of [1] to [8], wherein the first current collecting member has an inclined portion between the first region and the second region, and the gap formed between the inclined portion and the second current collecting member becomes gradually smaller toward the second region, and the gap has a region where the first insulating member is not disposed.

[0015]

[10] The secondary battery according to any one of [1] to [9], wherein the first current collecting member or the second current collecting member is provided with a fuse portion.

[0016]

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

[10] , wherein in a direction perpendicular to the first sealing plate, the difference between the surface of the third region on the side of the electrode body and the surface of the fourth region on the side of the electrode body is ±0.5 mm or less. [Effects of the Invention]

[0017] According to this technology, it is possible to provide a secondary battery with higher volumetric energy density and higher reliability. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a front view showing a configuration of a secondary battery according to an embodiment; [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] FIG. 2 is a perspective view showing a state before the sealing plate is fixed to the case body. [Figure 27] FIG. 2 is a side view showing the current collecting structure on the negative electrode side. [Figure 28] FIG. 28 is a perspective view of the configuration shown in FIG. 27. [Figure 29] 29 is a cross-sectional view taken along the line XXIX-XXIX in FIG. 28. [Figure 30] FIG. 2 is a perspective view of a first insulating member. [Figure 31] FIG. 4 is a perspective view of a second insulating member. [Figure 32] FIG. 10 is a first perspective view showing another embodiment of the joint portion of the current collector. [Figure 33] FIG. 10 is a second perspective view showing another embodiment of the joint portion of the current collector. [Figure 34] FIG. 10 is a third perspective view showing another embodiment of the joint portion of the current collector. [Figure 35] FIG. 10 is a fourth perspective view showing another embodiment of the joint portion of the current collector. [Figure 36] FIG. 10 is a fifth perspective view showing another embodiment of the joint portion of the current collector. 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: Overall structure of battery) Fig. 1 is a front view of a secondary battery 1 according to the present embodiment. Figs. 2 to 5 are views of 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 (second 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 (second sealing plate). The position of the negative electrode terminal 301 can be changed as appropriate.

[0039] 4, an opening 114 (first 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 (first 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 (second 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 (first 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 (second electrode tab group), and a positive electrode tab group 250 (first 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 (second 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 tab 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 (first 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 (first electrode) and a negative electrode (second 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 second 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 second 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 second 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 second 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] A third insulating member 510 is disposed between the plate-shaped member 303 and the sealing plate 120. A fourth insulating member 520 is disposed between the negative electrode terminal 301 and the sealing plate 120. A fifth 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 440 (second current collecting member). A first insulating member 460 is interposed between current collector 420 and current collector 440, but current collector 420 and current collector 440 are electrically joined at a position different from that shown in the cross section. Details will be described later.

[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] A third insulating member 510 is disposed between the plate-shaped member 304 and the sealing plate 130. A fourth insulating member 520 is disposed between the positive electrode terminal 302 and the sealing plate 130. A second 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 approximately rectangular parallelepiped (flat) electrode assembly 200, the insulating sheet 700 preferably covers the entire four faces other than the two faces on which the negative electrode tab group 220 and the positive electrode tab group 250 are formed, respectively.

[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 (second opening) and 114 (first 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 on the opening 113 side is disposed outside the case body 110, the negative electrode terminal 301 (second electrode terminal) provided on the sealing plate 120 (second sealing plate) and the negative electrode tab groups 220, 270 (second 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] (Current collector 420, current collector 440, first insulating member 460, second insulating member 470) 26 to 31, the specific configurations of current collector 420 (first current collecting member), current collector 440 (second current collecting member), first insulating member 460, and second insulating member 470 will be described. Fig. 26 is a perspective view showing the state before the sealing plate is fixed to the case body, Fig. 27 is a side view showing the current collecting structure on the negative electrode side, Fig. 28 is a perspective view of the configuration shown in Fig. 27, Fig. 29 is a cross-sectional view taken along line XXIX-XXIX in Fig. 28, Fig. 30 is a perspective view of first insulating member 460, and Fig. 31 is a perspective view of second insulating member 470.

[0134] 26 to 29, current collector 420 (first current collecting member) is a plate-like member having its longitudinal direction in the Z-axis direction and its transverse direction in the Y-axis direction. Current collector 420 includes a first region R1 and a second region R2. Current collector 420 is preferably made of aluminum or an aluminum alloy.

[0135] Current collector 440 (second current collecting member) is also a plate-like member having its longitudinal direction in the Z-axis direction and its lateral direction in the Y-axis direction, similar to current collector 42. Current collector 440 includes a third region R3 and a fourth region R4. Current collector 440 is preferably made of aluminum or an aluminum alloy.

[0136] In the current collector 440, in the direction perpendicular to the sealing plate 130, the difference between the surface of the third region R12 facing the electrode body 200 and the surface of the fourth region R4 facing the electrode body 200 may be ±0.5 mm or less (substantially flat).

[0137] A first insulating member 460 is disposed between the first region R1 of the current collector 420 and the third region R3 of the current collector 440.

[0138] 27, in the direction perpendicular to the sealing plate 130 (X direction), the surface of the second region R2 facing the sealing plate 130 is positioned closer to the sealing plate 130 than the surface of the first region R1 facing the sealing plate 130. To achieve this configuration, the current collector 420 may be formed by bending.

[0139] This configuration allows the second region R2 and the fourth region R4 to be joined, and the first insulating member 460 to be disposed between the first region R1 and the third region. This configuration stabilizes the position of the current collector 420 relative to the current collector 440, allowing for stable formation of the joint between the second region R2 and the fourth region R4 and preventing damage to the joint between the second region R2 and the fourth region R4. This results in a secondary battery with a highly reliable current collector connection structure. Furthermore, by connecting the positive electrode tab group 250 to the first region R1 of the current collector 420, the current collector structure can be more space-saving, allowing for the stable manufacture of secondary batteries with higher volumetric energy density. It is preferable that the positive electrode tab group 250 be bent and connected to the surface of the first region R1 facing the electrode assembly 200.

[0140] A second insulating member 470 is disposed between the sealing plate 130 and the current collector 440 as an insulating member different from the first insulating member 460. The configuration of the first insulating member 460 will be described in detail later, but the first insulating member 460 is provided with a protruding portion 460r that protrudes toward the sealing plate 130 side, and by engaging with an engaging groove 470a provided in the second insulating member 470, the first insulating member 460 is connected and fixed to the second insulating member 470. Note that the protruding portion 460r may be brought into contact with the sealing plate 130.

[0141] In the present embodiment, a connection and fixing structure is adopted in which first insulating member 460 is provided with protrusion 460r and second insulating member 470 is provided with engagement groove 470a, but first insulating member 460 may be provided with an engagement groove and second insulating member 470 with a protrusion. Furthermore, the connection and fixing structure is not limited to the structure of the present embodiment, and known fixing structures such as claw fitting and adhesive may be adopted.

[0142] A first contact portion TR1 is provided between the second region R2 of the current collector 420 and the fourth region R4 of the current collector 440, where the second region R2 and the fourth region R4 abut against each other. Furthermore, an end (the upper end in the drawing) of the first contact portion TR1 is provided with a joint SG1 joined by welding WD. Providing the first contact portion TR1 allows the end of the first contact portion TR1 to be stably welded. Furthermore, after the joint SG1 is formed, rattle of the first contact portion TR1 can be suppressed even when a load is applied to the first contact portion TR1.

[0143] For welding, welding using a high-energy beam is preferred, and laser welding using a laser beam is more preferred. This allows for the formation of a joint SG1 with high joint reliability. In this case, when high-energy beams are irradiated from the side of the current collectors 420 and 440 (from above in FIG. 29), it is preferable to form a V-shaped receiving portion by the first chamfered portion RT2 at the tip of the second region R2 and the second chamfered portion RT4 at the tip of the fourth region R4, as this facilitates the formation of the joint SG1. Note that high-energy beams can also be irradiated to one region (the current collector) to form the joint SG1 between the second region R2 and the fourth region R4 by full-penetration welding.

[0144] In the step of forming joint SG1, after inserting electrode body 200 into case body 110, in the step of joining current collector 420 and current collector 440, laser light is irradiated onto the chamfered portion of at least one of current collector 420 and current collector 440 from between case body 110 and sealing plate 130 to form joint SG1. Note that current collector 420 and current collector 440 may also be joined before electrode body 200 is inserted into case body 110.

[0145] The current collector 420 has an inclined portion T12 between the first region R1 and the second region R2, and a first gap S1 is provided between the inclined portion T12 and the current collector 440. This first gap S1 gradually becomes smaller toward the second region R2. Furthermore, the first gap S1 has a region where the first insulating member 460 is not disposed. By providing the first gap S1 in this manner, it is possible to prevent heat generated during the formation of the joint SG1 from escaping to the first region R1 and the third region R3, thereby enabling the joint SG1 to be formed stably and reducing heat transfer to the positive electrode tab groups 250, 280, the electrode assembly 200, and other conductive members.

[0146] Furthermore, the first gap S1 described above may be provided near the end of the first contact portion TR1 opposite to the end where the joint SG1 is formed. By providing the first gap S1, it is possible to prevent heat generated during the formation of the joint SG1 from escaping to the first region R1 and the fourth region R4, thereby enabling the joint SG1 to be formed stably.

[0147] 28, the current collector 420 in this embodiment is provided with a fuse portion HR. The fuse portion HR is preferably provided in the first region R1 of the current collector 420, closer to the second region R2 than the region (region indicated by R10) where the positive electrode tab groups 250, 280 are connected. The fuse portion HR preferably faces the first insulating member 460. The fuse portion HR may also be provided in the inclined portion T12.

[0148] The fuse portion HR is a portion that melts when a large current (e.g., a current that flows when an external short circuit occurs) flows through the current collector 420. The fuse portion HR is preferably a portion whose cross-sectional area is locally smaller than that of its surroundings. The fuse portion HR can be configured as a region of the current collector 420 where the cross-sectional area is reduced by a through-hole, a thin wall, a notch, a groove, or the like. The fuse portion HR may be provided in the current collector 440, instead of the current collector 420, with a similar structure. However, it is particularly preferable that the fuse portion HR be provided in the first region R1 of the current collector 420, which is located away from the current collector 440.

[0149] When a large current flows, the fuse portion HR melts and cuts off the large current, but it is preferable to avoid re-establishment of conduction between the portion of the current collector 420 to which the positive electrode tab group 250 is connected and the portion of the current collector 440 to which the positive electrode terminal 302 is connected after the fuse portion HR melts. In this embodiment, the first insulating member 460 is interposed between the first region R1 of the current collector 420 and the third region R3 of the current collector 440, and therefore, the possibility of re-establishment of conduction can be suppressed even after the fuse portion HR is activated.

[0150] Next, the detailed structure of the first insulating member 460 will be described with reference to Figure 30. The first insulating member 460 includes a flat plate portion 460a. This plate portion 460a has a bottom surface 460s and a pair of side walls 460b provided on each of the edges on both sides of the bottom surface 460s. A recess 460p is defined by the bottom surface 460s and the pair of side walls 460b. The thickness of the bottom surface 460s is not limited to this, but is preferably about 0.5 mm to 1.0 mm, for example.

[0151] The recess 460P is open on one side in a direction intersecting the direction in which the pair of sidewalls 460b are provided, and a first protrusion 460t is provided on the other side. Furthermore, protrusions 460r are provided on both edges of the first protrusion 460t on the side away from the bottom surface 460s. The protrusions 460r have a hook-like shape. Furthermore, the plate portion 460a is provided with a second protrusion 460y extending in the opposite direction to the direction in which the protrusions 460r extend.

[0152] Alternatively, a recess may be provided on the surface of plate portion 460a facing current collector 420, and at least a portion of current collector 420 may be disposed in the recess.

[0153] The surface of the plate portion 460a facing the sealing plate 130 preferably abuts against the third region R3 of the current collector 440. In addition, the surface of the plate portion 460a facing the electrode body 200 preferably abuts against the first region R1 of the current collector 420.

[0154] Next, the detailed structure of the second insulating member 470 will be described with reference to Fig. 31. The second insulating member includes a flat plate portion 470p. The plate portion 470p is provided with a through-hole 470h for passing the positive electrode terminal 302 therethrough. Furthermore, both edges on one end side of the plate portion 470P are provided with engagement grooves 470a for engaging with the protrusions 460r provided on the first insulating member 460. The thickness of the plate portion 470P is not limited to this, but is preferably about 0.5 mm to 1.0 mm, for example.

[0155] The form of the protrusion 460r and the engagement groove 470a is not limited to this embodiment, and other known engagement structures can be adopted as long as the engagement between the two connects and fixes the first insulating member 460 and the second insulating member 470. Note that the connection between the first insulating member 460 and the second insulating member 470 is not necessarily required.

[0156] 29 and 30 , in a state in which current collector 420, first insulating member 460, current collector 440, and second insulating member 470 are fixed to sealing plate 130, at least a portion of current collector 440 is housed in recess 460P of first insulating member 460, and current collector 440 is positioned by first protrusion 460t of first insulating member 460. Furthermore, protrusion 460r provided on first insulating member 460 engages with engagement groove 470a of the second insulating member, whereby current collector 440 is fixed in a state in which it is sandwiched between first insulating member 460 and second insulating member 470.

[0157] Furthermore, it is preferable that the end of the first region R1 of the current collector 420 be in contact with and positioned on the second protrusion 460y provided on the first insulating member 460. As a result, the relative positions of the current collector 420 and the current collector 440 are more stably fixed, thereby stabilizing the joining state of the first contact portion TR1 between the second region R2 of the current collector 420 and the fourth region R4 of the current collector 440.

[0158] (Other embodiments) 32 to 36, other configurations of the second region R2 of the current collector 420 and the fourth region R4 of the current collector 440 will be described. FIGS. 32 to 36 are first to fifth perspective views showing other configurations of the joint between the second region R2 of the current collector 420 and the fourth region R4 of the current collector 440.

[0159] 26, the joint configuration shown in Fig. 32 is such that the fourth region R4 of the current collector 440 is spaced apart from the second insulating member 470. Even in this joint configuration, the joint SG1 faces in the Z direction, which facilitates the joining of the second region R2 and the fourth region R4. Furthermore, by spaced apart the joint SG1 from the second insulating member 470, damage to the second insulating member 470 due to the influence of heat can be suppressed.

[0160] In the joint configuration shown in FIG. 33, the second region R2 of the current collector 420 is bent perpendicularly toward the electrode assembly 200, and the fourth region R4 of the current collector 440 is also bent perpendicularly toward the electrode assembly 200 so as to align with the second region R2. As a result, an overlapping region R11 is provided between the second region R2 and the fourth region R4, and the joint SG1 is formed in this region. With this joint configuration, the joint SG1 faces in the Z direction, which facilitates the joining of the second region R2 and the fourth region R4. Furthermore, the distance between the joint SG1 and the second insulating member 470 reduces damage to the second insulating member 470 due to the effects of heat. Furthermore, the area in which the joint SG1 is formed can be increased.

[0161] In the joint configuration shown in FIG. 34, the second region R2 of the current collector 420 is bent so as to protrude toward the electrode body 200, and the fourth region R4 of the current collector 440 is also bent toward the electrode body 200 so as to align with the second region R2. As a result, an overlapping region R11 between the second region R2 and the fourth region R4 is provided at an angle with respect to the sealing plate 130, and a joint SG1 is formed in this region R11. With this joint configuration, the joint SG1 faces diagonally in the Z direction, which facilitates the joining of the second region R2 and the fourth region R4. Furthermore, because the joint SG1 is spaced apart from the second insulating member 470, damage to the second insulating member 470 due to the effects of heat can be suppressed.

[0162] In the joint configuration shown in FIG. 35, the second region R2 of the current collector 420 is provided to extend in the Z direction so as to be closer to the electrode assembly 200 than the first region R1, and the fourth region R4 of the current collector 430 is also provided to extend in the Z direction along the second region R2. Furthermore, the end of the fourth region R4 is provided to protrude beyond the end of the second region R2. As a result, the joint SG1 can be formed in the fourth region R4 protruding from the second region R2, facilitating welding from an oblique direction. Furthermore, by separating the joint SG1 from the second insulating member 470, damage to the second insulating member 470 due to the effects of heat can be suppressed.

[0163] In the joint configuration shown in FIG. 36, the second region R2 of the current collector 420 is provided with a first extension R21 extending obliquely upward from its tip toward the electrode assembly 200. The fourth region R4 of the current collector 440 is spaced apart from the second insulating member 470 so as to contact the second region R2. Furthermore, the tip of the fourth region R4 is provided with a second extension R41 that bends toward the second insulating member 470. As a result, the first extension R21 and the second extension R41 form a receiving portion with a V-shaped cross section. Forming the receiving portion in this manner allows the formation of a joint SG1 in this receiving portion, facilitating welding. Furthermore, the separation of the joint SG1 from the second insulating member 470 can suppress damage to the second insulating member 470 due to the effects of heat.

[0164] 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]

[0165] 1 secondary battery, 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 portion, 206 second end portion, 207 third end portion, 208 fourth end portion, 210 negative electrode plate, 211 negative electrode core body, 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 body, 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 protrusion, 410q1 tip surface, 410q2 outer surface, 411, 421 joint portion, 430p recess, 430p1 bottom surface, 430p2 inner surface, 460 first insulating member, 460a plate portion, 460s bottom surface, 460b side wall portion, 460p Recess, 460t first convex portion, 460r protruding portion, 460y second convex portion, 470 second insulating member, 470p plate portion, 470h through hole, 470a engaging groove, 510 third insulating member, 520 fourth insulating member, 530 fifth 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 insulating sheet, 800 separator.

Claims

1. an electrode body including a first electrode and a second electrode having a polarity different from that of the first electrode; a case body that houses the electrode body and has a first opening; a first sealing plate that seals the first opening; a first electrode tab electrically connected to the first electrode; a first current collecting member electrically connected to the first electrode tab; a second current collecting member joined to the first current collecting member; a first electrode terminal electrically connected to the second current collecting member and provided on the first sealing plate; A secondary battery comprising: the first current collecting member includes a first region and a second region; the second current collecting member includes a third region and a fourth region, the first electrode tab is connected to the first region; the second region and the fourth region are joined together, a first insulating member is disposed between the first region and the third region; Secondary battery.

2. the first insulating member has a protruding portion that protrudes toward the first sealing plate, the protrusion abuts against the first sealing plate or another insulating member arranged on the first sealing plate; The secondary battery according to claim 1 .

3. a second insulating member is disposed between the first sealing plate and the second current collecting member; the other insulating member is the second insulating member, the protruding portion abuts against the second insulating member; The secondary battery according to claim 2 .

4. The first insulating member is connected and fixed to the second insulating member. The secondary battery according to claim 3 .

5. the case body has a second opening at a position opposite to the first opening, and the second opening is sealed by a second sealing plate; a second electrode terminal electrically connected to the second electrode is provided on the second sealing plate, the electrode body is provided with the first electrode tab at an end on the first sealing plate side, and with a second electrode tab electrically connected to the second electrode at an end on the second sealing plate side; The secondary battery according to claim 1 .

6. a first contact portion where the second region and the fourth region contact each other; a joint portion where the first current collecting member and the second current collecting member are joined is provided at an end portion of the first abutting portion; The secondary battery according to claim 1 .

7. In a direction perpendicular to the first sealing plate, a surface of the second region on the first sealing plate side is located closer to the first sealing plate than a surface of the first region on the first sealing plate side; The secondary battery according to claim 1 .

8. the first insulating member includes a plate portion, the plate portion has a recess; At least a portion of the first current collecting member or the second current collecting member is disposed in the recess. The secondary battery according to claim 1 .

9. the first current collecting member has an inclined portion between the first region and the second region, a gap formed between the inclined portion and the second current collecting member gradually decreases toward the second region, The gap has a region where the first insulating member is not disposed. The secondary battery according to claim 1 .

10. a fuse portion is provided on the first current collecting member or the second current collecting member, The secondary battery according to claim 1 .

11. In a direction perpendicular to the first sealing plate, a difference between a surface of the third region on the side of the electrode body and a surface of the fourth region on the side of the electrode body being ±0.5 mm or less; The secondary battery according to claim 1 .

Images