Secondary battery and method of manufacturing the same

Abstract

To provide a secondary battery with high energy density and high reliability, and a method of manufacturing the secondary battery.SOLUTION: A secondary battery comprises: an electrode assembly including a positive electrode and a negative electrode; a case that accommodates the electrode assembly, the case including a case main body with an opening and also including a sealing plate that seals the opening; an electrode terminal provided on an outer surface of the sealing plate; and a current collecting portion that electrically connects the electrode assembly and the electrode terminal. The current collecting portion includes: a first member having electric conductivity, the first member being joined to the electrode assembly; a second member having electric conductivity, the second member being fixed on an inner surface of the sealing plate, the second member being joined to the electrode terminal; and a third member having electric conductivity, the third member being constituted of a member different from the first member and the second member, the third member electrically connecting the first member and the second member.SELECTED DRAWING: Figure 24

Description

[Technical Field]

[0001] The present technology relates to a secondary battery and a manufacturing method thereof. [Background technology]

[0002] Japanese Patent No. 4537353 (Patent Document 1) shows a rectangular secondary battery in which an electrode group (25) is housed in a case (14) having openings (14a, 14b) at both ends, and electrode terminals (21, 23) are attached to cap plates (33, 33') that seal the openings (14a, 14b).

[0003] Japanese Patent Publication No. 2015-524148 (Patent Document 2), Japanese Patent Publication No. 2013-535774 (Patent Document 3), and Japanese Patent Laid-Open No. 2018-77933 (Patent Document 4) disclose the application of wire bonding or ribbon bonding to electrical connections in batteries. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4537353 [Patent Document 2] Special Publication No. 2015-524148 [Patent Document 3] Special Publication No. 2013-535774 [Patent Document 4] Japanese Patent Application Publication No. 2018-77933 Summary of the Invention [Problem to be solved by the invention]

[0005] There is a demand for improved energy density and reliability of secondary batteries. From these perspectives, there is still room for improvement in conventional secondary batteries.

[0006] An object of the present technology is to provide a secondary battery with high energy density and high reliability, and a method for manufacturing the secondary battery. [Means for solving the problem]

[0007] The present technology provides the following secondary battery and method for manufacturing the same.

[0008] [1] A secondary battery comprising: a case including an electrode body including a positive electrode and a negative electrode, a case body having an opening, and a sealing plate that seals the opening, and accommodating the electrode body; electrode terminals provided on the outer surface of the sealing plate; and a current collecting part that electrically connects the electrode body and the electrode terminals, wherein the current collecting part includes a conductive first member joined to the electrode body, a conductive second member fixed to the inner surface of the sealing plate and joined to the electrode terminals, and a conductive third member made of a member separate from the first member and the second member and electrically connecting the first member and the second member.

[0009] [2] The secondary battery according to [1], wherein the third member is made of a conductive linear member or strip-shaped member.

[0010] [3] The secondary battery according to [1] or [2], wherein the case has a substantially rectangular parallelepiped shape.

[0011] [4] The secondary battery according to any one of [1] to [3], wherein the case body has a first opening and a second opening located on both sides in a first direction, the sealing plate includes a first sealing plate and a second sealing plate that seal the first opening and the second opening, respectively, the electrode terminal includes a positive electrode terminal or a negative electrode terminal provided on an outer surface of one of the first sealing plate and the second sealing plate, and the current collecting portion is provided between the electrode body and the positive electrode terminal or the negative electrode terminal, respectively.

[0012] [5] The secondary battery according to any one of [1] to [4], wherein the third member has a conductive area that can tolerate charging equivalent to 1 C.

[0013] [6] The secondary battery according to any one of [1] to [5], wherein the third member is made of a single member.

[0014] [7] The secondary battery according to any one of [1] to [5], wherein the third member is made of a plurality of members.

[0015] [8] A method for manufacturing a secondary battery, comprising the steps of: inserting an electrode body including a positive electrode and a negative electrode into a case body through an opening; providing an electrode terminal on the outer surface of a sealing plate; sealing the opening with the sealing plate; and electrically connecting the electrode body and the electrode terminal via a current collecting portion, wherein the step of electrically connecting the electrode body and the electrode terminal includes joining a conductive first member to the electrode body; fixing a conductive second member on the inner surface of the sealing plate and joining it to the electrode terminal; and electrically connecting the first member and the second member via a conductive third member made of a material different from the first member and the second member.

[0016] [9] The method for manufacturing a secondary battery according to [8], wherein the third member is made of a conductive linear member or strip-shaped member.

[0017]

[10] The method for manufacturing a secondary battery according to [8] or [9], wherein the case consisting of the case body and the sealing plate has a substantially rectangular parallelepiped shape.

[0018]

[11] The method for manufacturing a secondary battery according to any one of [8] to

[10] , wherein the case body has a first opening and a second opening located on both sides in a first direction, the sealing plate includes a first sealing plate and a second sealing plate that seal the first opening and the second opening, respectively, the electrode terminal includes a positive electrode terminal or a negative electrode terminal provided on an outer surface of one of the first sealing plate and the second sealing plate, and the current collecting portion is provided between the electrode body and the positive electrode terminal or the negative electrode terminal.

[0019]

[12] A method for manufacturing a secondary battery described in any one of [8] to

[11] , wherein the first member and the second member are electrically connected via the third member after the electrode body is inserted into the case body.

[0020]

[13] The method for manufacturing a secondary battery according to any one of [8] to

[12] , wherein the third member has a conductive area that can tolerate charging equivalent to 1 C.

[0021]

[14] The method for manufacturing a secondary battery according to any one of [8] to

[13] , wherein the third member is made of a single member.

[0022]

[15] The method for manufacturing a secondary battery according to any one of [8] to

[13] , wherein the third member is made of a plurality of members. [Effects of the Invention]

[0023] According to the present technology, it is possible to provide a secondary battery with high energy density and high reliability, and a method for manufacturing the secondary battery. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a front view showing the configuration of a secondary battery according to Embodiment 1. FIG. [Figure 2] 2 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow II. [Figure 3] 3 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow III. [Figure 4] 4 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow IV. FIG. [Figure 5] 2 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow V. FIG. [Figure 6] FIG. 2 is a front cross-sectional view of the secondary battery shown in FIG. [Figure 7] FIG. 2 is a front view showing a negative electrode blank before being formed into a negative electrode plate. [Figure 8] 8 is a cross-sectional view taken along the line VIII-VIII of the negative electrode plate shown in FIG. 7. [Figure 9] FIG. 2 is a front view showing a negative electrode plate formed from a negative electrode original plate. [Figure 10] FIG. 2 is a front view showing a positive electrode plate before it is formed into a positive electrode plate. [Figure 11] 11 is a cross-sectional view of the positive electrode plate taken along the line XI-XI in FIG. 10. [Figure 12] FIG. 2 is a front view showing a positive electrode plate formed from a positive electrode original plate. [Figure 13] 1. FIG. 2 is a cross-sectional view of the secondary battery shown in FIG. [Figure 14] 1. FIG. 2 is a cross-sectional view of the secondary battery shown in FIG. [Figure 15] 3 is a flowchart showing a method for manufacturing a secondary battery according to the first embodiment. [Figure 16] 1 is a perspective view showing a state before two electrode bodies included in the secondary battery according to Embodiment 1 are overlapped. [Figure 17] 17 is a cross-sectional view taken along the line XVII-XVII of the electrode body and current collector shown in FIG. 16. FIG. [Figure 18] FIG. 2 is a perspective view showing a state in which a holder and a spacer are attached to an electrode body. [Figure 19] FIG. 2 is a perspective view showing a state in which a sealing plate is attached to a negative electrode-side current collector. [Figure 20] 20 is a cross-sectional view of the electrode body and current collector shown in FIG. 19 taken along the line XX-XX. [Figure 21] FIG. 2 is a perspective view showing a state in which an electrode body is being inserted into a case main body. [Figure 22] 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 23] 23 is a cross-sectional view taken along the line XXIII-XXIII of the electrode body and current collector shown in FIG. 22. [Figure 24] FIG. 23 is a diagram showing the current collector shown in FIG. 22 as viewed from the direction of arrow XXIV. [Figure 25] 25 is a cross-sectional view of the current collector shown in FIG. 24 taken along the line XXV-XXV. [Figure 26] 1 is a perspective view showing the configuration of a secondary battery according to Embodiment 1. FIG. [Figure 27] FIG. 10 is a cross-sectional view showing the configuration of a secondary battery according to a second embodiment. [Figure 28] FIG. 10 is a perspective view showing the configuration of a current collector included in a secondary battery according to a third embodiment. [Figure 29] 29 is a cross-sectional view of the current collector shown in FIG. 28 taken along the line XXIX-XXIX. [Figure 30] FIG. 10 is a perspective view showing the configuration of a current collector included in a secondary battery according to Embodiment 4. [Figure 31] 31 is a cross-sectional view taken along the line XXXI-XXXI of the current collector shown in FIG. 30. [Figure 32] FIG. 10 is a perspective view showing the configuration of a current collector included in a secondary battery according to a fifth embodiment. [Figure 33] 33 is a cross-sectional view of the current collector shown in FIG. 32 taken along the line XXXIII-XXXIII. [Figure 34] FIG. 13 is a perspective view showing the configuration of a current collector included in a secondary battery according to a sixth embodiment. [Figure 35] 35 is a cross-sectional view of the current collector shown in FIG. 34 taken along the line XXXV-XXXV. [Figure 36] FIG. 13 is a cross-sectional view showing the structure of a current collector included in a secondary battery according to a seventh embodiment. [Figure 37] FIG. 1 is a top view (part 1) showing a configuration example of a connection member. [Figure 38] FIG. 38 is a side view of the structure shown in FIG. 37. [Figure 39] FIG. 10 is a top view (part 2) showing a configuration example of the connection member. [Figure 40] FIG. 40 is a side view of the structure shown in FIG. 39. [Figure 41] FIG. 10 is a top view (part 3) showing a configuration example of the connection member. [Figure 42] FIG. 42 is a side view of the structure shown in FIG. 41. DETAILED DESCRIPTION OF THE INVENTION

[0025] 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.

[0026] 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 and advantages mentioned in the present embodiments.

[0027] In this specification, the terms "comprise," "include," and "have" are open-ended. That is, when a certain feature is included, other features may or may not be included.

[0028] Furthermore, when geometric terms and terms expressing positional and directional relationships are used in this specification, such as "parallel," "orthogonal," "45° diagonal," "coaxial," and "along," 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).

[0029] 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.

[0030] In the drawings, the direction along the winding axis of the electrode body provided in the secondary battery 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. Also, to make the invention easier to understand, the dimensions of each component in the drawings may be shown differently from the actual dimensions.

[0031] In this specification, the first direction (X direction) may be referred to as the "width direction" of the secondary battery or the case body, the second direction (Y direction) may be referred to as the "thickness direction" of the secondary battery or the case body, and the third direction (Z direction) may be referred to as the "height direction" of the secondary battery or the case body.

[0032] (Embodiment 1) The secondary battery 1 according to the first embodiment will be described below.

[0033] (Overall battery configuration) 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.

[0034] 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.

[0035] 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, and a sealing plate .

[0036] 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.

[0037] 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.

[0038] As shown in Figures 1 and 2, a sealing plate 120 (second wall) and a sealing plate 130 (first 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 (joint 115 shown in Figure 2) and joining them together (for example, by laser welding). The corners of the "rectangular tube" may be rounded.

[0039] 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.

[0040] 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.

[0041] 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 gas release valve 150 can be modified as appropriate.

[0042] 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.

[0043] 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.

[0044] 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. Note that the generally rectangular shape includes a rectangular shape or a substantially rectangular shape such as a rectangular shape with rounded corners.

[0045] 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.

[0046] 4, an opening 114 (first opening) is provided at an end of a second side opposite the first side in a first direction (X direction) of case body 110. 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.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] The positive electrode terminal 302 is electrically connected to the positive electrode of the electrode assembly 200. The positive electrode terminal 302 is attached to the sealing plate 130, i.e., the case 100.

[0051] The negative electrode terminal 301 (first electrode terminal) 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.

[0052] 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.

[0053] 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.

[0054] The electrode assembly 200 is a flat-shaped electrode assembly having positive and negative electrode plates, as described below. Specifically, the electrode assembly 200 is a wound-type electrode assembly in which a strip-shaped positive electrode plate and a strip-shaped negative electrode plate are wound together via a strip-shaped separator (not shown). However, in this specification, the term "electrode assembly" is not limited to a wound-type electrode assembly and may also be a stacked-type electrode assembly in which multiple positive electrode plates and multiple negative electrode plates are alternately stacked. The strip-shaped separator may be formed, for example, of a polyolefin microporous membrane. The electrode assembly may include multiple positive electrode plates and multiple negative electrode plates, and the positive electrode tabs provided on each positive electrode plate may be stacked to form a positive electrode tab group, or the negative electrode tabs provided on each negative electrode plate may be stacked to form a negative electrode tab group. The electrode assembly 200 may include multiple wound-type electrode bodies or multiple stacked-type electrode bodies.

[0055] As shown in Fig. 6, case 100 houses electrode assembly 200. Fig. 6 illustrates a first electrode assembly 201, which will be described later. First electrode assembly 201 is housed in case 100 so that its winding axis is parallel to the X direction.

[0056] Specifically, one or more wound 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 diethyl carbonate (DEC) in a volume ratio (25°C) of 30:30:40, in which LiPF is dissolved at a concentration of 1.2 mol / L. Note that a solid electrolyte may be used instead of the electrolytic solution.

[0057] The first electrode body 201 includes a main body portion (a portion where positive electrode plates and negative electrode plates are stacked with a separator interposed therebetween), a negative electrode tab group 220 (second electrode tab group), and a positive electrode tab group 250 (first electrode tab group).

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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 aluminum or an aluminum alloy, for example. 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. The positive electrode current collector 400B will be described in detail later.

[0063] (Configuration of electrode body 200) FIG. 7 is a front view showing the negative electrode plate 210S before the negative electrode plate 210 is formed, FIG. 8 is a cross-sectional view taken along line VIII-VIII of the negative electrode plate 210S shown in FIG. 7, and FIG. 9 is a front view showing the negative electrode plate 210 formed from the negative electrode plate 210S.

[0064] The negative electrode plate 210 is manufactured by processing a negative electrode original plate 210S. As shown in Figures 7 and 8, the negative electrode original plate 210S includes a negative electrode core 211 (second electrode core) and a negative electrode active material layer 212. The negative electrode core 211 is a copper foil or a copper alloy foil.

[0065] A negative electrode active material layer 212 is formed on both surfaces of the negative electrode substrate 211 except for one end portion. The negative electrode active material layer 212 is formed by applying a negative electrode active material layer slurry using a die coater.

[0066] The negative electrode active material layer slurry is prepared by kneading graphite as the negative electrode active material, styrene butadiene rubber (SBR) and carboxymethyl cellulose (CMC) as binders, and water as a dispersion medium so that the mass ratio of graphite:SBR:CMC is approximately 98:1:1.

[0067] The negative electrode substrate 211 coated with the negative electrode active material layer slurry is dried to remove water contained in the negative electrode active material layer slurry, thereby forming the negative electrode active material layer 212. The negative electrode active material layer 212 is then compressed to form a negative electrode base plate 210S including the negative electrode substrate 211 and the negative electrode active material layer 212. The negative electrode base plate 210S is cut into a predetermined shape to form the negative electrode plate 210. The negative electrode base plate 210S can be cut by laser processing using energy beam irradiation, mold processing, cutter processing, or the like.

[0068] As shown in FIG. 9 , 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 a negative electrode plate 210 formed from a negative electrode original plate 210S. When the negative electrode plate 210 is wound, the plurality of negative electrode tabs 230 are stacked to form a negative electrode tab group 220. As a result, the negative electrode tab group 220 is connected to the negative electrode plate 210. The position and length in the protruding direction of each of the plurality of negative electrode tabs 230 are appropriately adjusted taking into account the state in which the negative electrode tab group 220 is connected to the negative electrode current collector 400A. Note that the shape of the negative electrode tab 230 is not limited to the example shown in FIG. 8 .

[0069] FIG. 10 is a front view showing a positive electrode plate 240S before the positive electrode plate 240 is formed, FIG. 11 is a cross-sectional view taken along line XI-XI of the positive electrode plate 240S shown in FIG. 10, and FIG. 12 is a front view showing a positive electrode plate 240 formed from the positive electrode plate 240S.

[0070] The positive electrode plate 240, which is the second electrode, has a polarity different from that of the negative electrode plate 210, which is the first electrode. The positive electrode plate 240 is manufactured by processing a positive electrode base plate 240S. As shown in FIGS. 10 and 11, the positive electrode base plate 240S includes a positive electrode core 241 (first electrode core), a positive electrode active material layer 242, and a positive electrode protective layer 243. The positive electrode core 241 is an aluminum foil or an aluminum alloy foil.

[0071] A positive electrode active material layer 242 is formed on both surfaces of the positive electrode core 241 except for one end portion. The positive electrode active material layer 242 is formed on the positive electrode core 241 by applying a positive electrode active material layer slurry using a die coater.

[0072] The positive electrode active material layer slurry is prepared by kneading lithium nickel cobalt manganese composite oxide as the positive electrode active material, polyvinylidene fluoride (PVdF) as a binder, a carbon material as a conductive material, and N-methyl-2-pyrrolidone (NMP) as a dispersion medium so that the mass ratio of lithium nickel cobalt manganese composite oxide:PVdF:carbon material is approximately 97.5:1:1.5.

[0073] The positive electrode protective layer 243 is in contact with the positive electrode core 241 and is formed on one end of the positive electrode active material layer 242 in the width direction. The positive electrode protective layer 243 is formed on the positive electrode core 241 by applying a positive electrode protective layer slurry using a die coater. The positive electrode protective layer 243 has a larger electrical resistance than the positive electrode active material layer 242.

[0074] The positive electrode protective layer slurry is prepared by kneading alumina powder, a carbon material as a conductive material, PVdF as a binder, and NMP as a dispersion medium so that the mass ratio of alumina powder:carbon material:PVdF is approximately 83:3:14.

[0075] The positive electrode substrate 241 coated with the positive electrode active material layer slurry and the positive electrode protective layer slurry is dried, and the NMP contained in the positive electrode active material layer slurry and the positive electrode protective layer slurry is removed, thereby forming the positive electrode active material layer 242 and the positive electrode protective layer 243. The positive electrode active material layer 242 is then compressed to form a positive electrode base plate 240S including the positive electrode substrate 241, the positive electrode active material layer 242, and the positive electrode protective layer 243. The positive electrode base plate 240S is cut into a predetermined shape to form the positive electrode plate 240. The positive electrode base plate 240S can be cut by laser processing using energy beam irradiation, mold processing, cutter processing, or the like.

[0076] As shown in FIG. 12, 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 a positive electrode plate 240 formed from a positive electrode original plate 240S. When the positive electrode plate 240 is wound, the plurality of positive electrode tabs 260 are stacked to form a positive electrode tab group 250. As a result, the positive electrode tab group 250 is connected to the positive electrode plate 240. The position and length in the protruding direction of each of the plurality of positive electrode tabs 260 are appropriately adjusted taking into account 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 tabs 260 is not limited to the example shown in FIG. 12.

[0077] A positive electrode protective layer 243 is provided at the base of each of the positive electrode tabs 260. The positive electrode protective layer 243 does not necessarily have to be provided at the base of the positive electrode tab 260.

[0078] 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.

[0079] (Connection structure between electrode body 200 and current collector 400) Fig. 13 is a cross-sectional view taken along line XIII-XIII of the secondary battery shown in Fig. 1. As shown in Fig. 13, 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). Note that the electrode body 200 may be composed of three or more electrode bodies.

[0080] 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.

[0081] The first electrode body 201 includes a negative electrode tab group 220. The negative electrode tab group 220 is electrically connected to a 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 a current collector 430 (negative electrode current collector) at a third end 207 in the X direction.

[0082] The negative electrode tab group 220 has a curved portion 221 and a tip portion 222. The curved portion 221 is a portion of the negative electrode tab group 220 that is curved on the side where the first electrode is connected, relative to the tip portion 222. The tip portion 222 is a portion of the negative electrode tab group 220 that is located at the end opposite the side where the first electrode is connected.

[0083] The negative electrode tab group 270 has a curved portion 271 and a tip portion 272. The curved portion 271 is a portion of the negative electrode tab group 270 that is curved on the side where the first electrode is connected, relative to the tip portion 272. The tip portion 272 is a portion of the negative electrode tab group 270 that is located at the end opposite the side where the first electrode is connected.

[0084] 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.

[0085] 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.

[0086] The negative electrode current collector 400A includes a current collector 410 and a current collector 430 (first members), and a current collector 440 (second member).

[0087] 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.

[0088] The negative electrode tab group 220 is joined to the current collector 410 at joining points 411, which will be described later. The negative electrode tab group 270 is joined to the current collector 430 at joining points 431, which will be described later. The joining points 411, 431 can be formed by, for example, ultrasonic welding, resistance welding, laser welding, crimping, or the like. In the present embodiment, the negative electrode tab group 220 and the current collector 410, and the negative electrode tab group 270 and the current collector 430 are joined by, for example, ultrasonic welding.

[0089] Current collector 440 is electrically connected to current collectors 410 and 430. Current collector 440 is connected to negative electrode terminal 301. The connection between current collector 440 and negative electrode terminal 301 can be formed by, for example, crimping and / or welding.

[0090] Negative electrode terminal 301 is provided so as to be exposed to the outside of sealing plate 120 and to reach current collector 440 of negative electrode current collector 400A provided on the inside surface of sealing plate 120. Negative electrode terminal 301 is connected to plate-shaped member 303.

[0091] 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 other adjacent secondary batteries. The connection between the negative electrode terminal 301 and the plate-shaped member 303 can be formed by, for example, laser welding.

[0092] 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 440 and the sealing plate 120.

[0093] 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.

[0094] A spacer 600 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 spacer 600 includes a first component 610 and a second component 620. The first component 610 and the second component 620 are engaged with each other at engagement portions (not shown) at both ends in the Z direction.

[0095] The first component 610 and the second component 620 protrude in the Y direction at the end on the electrode body 200 side in the X direction. As a result, 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.

[0096] 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).

[0097] Fig. 14 is a cross-sectional view taken along the line XIV-XIV of the secondary battery shown in Fig. 1. The connection structure between electrode body 200 and current collector 400 on the positive electrode side of secondary battery 1 in this embodiment differs from the structure on the negative electrode side in that the portions corresponding to current collectors 410 and 430 on the negative electrode side are formed from a single component.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] 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, 282 are spaced apart, but this configuration is not limiting, and the tip portions 252, 282 may be in contact with each other.

[0102] 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.

[0103] The positive electrode current collector 400B includes a current collector 420 (first member) and a current collector 450 (second member).

[0104] 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.

[0105] 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, 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.

[0106] Current collector 450 is electrically connected to current collector 420. Current collector 450 is connected to positive electrode terminal 302. The connection between current collector 450 and positive electrode terminal 302 can be formed by, for example, crimping and / or welding.

[0107] Positive electrode terminal 302 is exposed to the outside of sealing plate 130 and is provided so as to reach current collector 450 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.

[0108] 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 other adjacent secondary batteries. The connection between the positive electrode terminal 302 and the plate-shaped member 304 can be formed by, for example, laser welding.

[0109] 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 530 is disposed between the current collector 450 and the sealing plate 130.

[0110] 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.

[0111] A spacer 600 is disposed between the sealing plate 130 and the main body of the electrode body 200 (excluding the positive electrode tab groups 250, 280). The spacer 600 is made of an insulating resin material. The spacer 600 includes a first component 610 and a second component 620. The first component 610 and the second component 620 are engaged with each other at engagement portions (not shown) at both ends in the Z direction.

[0112] The first component 610 and the second component 620 protrude in the Y direction at the end on the electrode body 200 side in the X direction. As a result, 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.

[0113] Between the electrode body 200 and the case body 110, an insulating sheet 700 (electrode body holder) made of resin is arranged.

[0114] (Manufacturing process of secondary battery 1) A method for manufacturing a secondary battery according to the present embodiment will be described below. Fig. 15 is a flowchart showing a method for manufacturing a secondary battery according to embodiment 1. Fig. 16 is a perspective view showing a state before two electrode bodies included in the secondary battery according to embodiment 1 are overlapped. Fig. 17 is a cross-sectional view taken along line XVII-XVII of the electrode body and current collector shown in Fig. 16.

[0115] 15, 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). 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.

[0116] As shown in FIGS. 15 to 17, after the first electrode body 201 and the second electrode body 202 are fabricated, the negative electrode tab group 220 is joined to the current collector 410 (step S2). The negative electrode tab group 220 is joined to the current collector 410 at joining locations 411. Next, the negative electrode tab group 270 is joined to the current collector 430 (step S3). The negative electrode tab group 270 is joined to the current collector 430 at joining locations 431.

[0117] Next, the first electrode body 201, the current collector 420, and the second electrode body 202 are arranged in this order in the DR1 direction. The positive electrode tab group 250 is arranged on one side of the current collector 420 in the DR1 direction. With the positive electrode tab group 280 arranged on the other side of the current collector 420 in the 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.

[0118] In the height direction of the first electrode body 201 and the second electrode body 202, the current collector 410, the current collector 420, and the current collector 430 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.

[0119] It should be noted that the current collector 410, the current collector 420, and the current collector 430 are not limited to this configuration. The current collector 410, the current collector 420, and the current collector 430 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, the current collector 420, and the current collector 430 in the height direction of the first electrode body 201 and the second electrode body 202.

[0120] Furthermore, the order of the steps of joining the current collector 410, the current collector 420, and the current collector 430 to the first electrode body 201 and the second electrode body 202 is not limited to the above, and the order may be changed. The steps of joining the current collector 410 and the current collector 430 to the first electrode body 201 and the second electrode body 202, respectively, are preferably performed before the step of overlapping 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.

[0121] 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. 16 and 17), and the first electrode body 201 and the second electrode body 202 are overlapped (step S5). In other words, the first electrode body 201 and the second electrode body 202 are gathered together.

[0122] "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 disposed 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 DR1 direction, and the first electrode body or the second electrode body may be inclined with respect to the current collector in the DR1 direction.

[0123] 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.

[0124] 15 and 18 are perspective views showing a state in which the holder and spacer are attached to the electrode assembly. As shown in Fig. 18, next, the spacer 600 and the insulating sheet 700 are assembled to the electrode assembly 200 (step S6).

[0125] The insulating sheet 700 does not necessarily have to cover the entire surface of the electrode assembly 200. The insulating sheet 700 preferably covers approximately 50% or more, and more preferably approximately 70% or more, of the area of ​​the outer surface of the electrode assembly. Of the six faces of the substantially rectangular parallelepiped (flat) electrode assembly 200, the insulating sheet 700 preferably covers the entire four faces other than the two faces on which the negative electrode tab group 220 and the positive electrode tab group 250 are formed, respectively.

[0126] 19 is a perspective view showing a state in which a sealing plate 120 is attached to the negative electrode side current collector. FIG. 20 is a cross-sectional view taken along the line XX-XX of the electrode assembly and current collector shown in FIG.

[0127] 15, 19, and 20, 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, and then the current collector 410 and the current collector 430 are electrically connected to the negative electrode terminal 301 via the current collector 440 (step S7). Note that step S7 can also be performed before step S6.

[0128] 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.

[0129] The negative electrode terminal 301 and the current collector 440 are attached to the sealing plate 120 via an insulating member. The current collector 440 is brought into contact with the current collectors 410 and 430 in the X direction. The current collector 440 is then electrically connected to the current collectors 410 and 430. Note that the timing of connecting the plate-like member 303 to the negative electrode terminal 301 may be any.

[0130] 21 is a perspective view showing the state in which the electrode bodies are being inserted into the case body. Next, as shown in Fig. 15 and Fig. 21, after the first electrode body 201 and the second electrode body 202 are overlapped, the first electrode body 201 and the second electrode body 202 are inserted into the case body 110 from the opening 113, with the current collector 420 side first (step S8).

[0131] 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 case main body 110 are brought closer to each other by bringing the sealing plate 120 and the main body of the electrode body 200 arranged in the case main body 110 closer to each other. As shown in FIG. 13 , 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 main body 110 in the Y direction.

[0132] 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.

[0133] 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.

[0134] Fig. 22 is a perspective view showing a state in which a sealing plate 130 is attached to the positive electrode side current collector. Fig. 23 is a cross-sectional view taken along line XXIII-XXIII of the electrode assembly and current collector shown in Fig. 22. Fig. 24 is a view showing the current collector shown in Fig. 22 as viewed from the direction of arrow XXIV. Fig. 25 is a cross-sectional view taken along line XXV-XXV of the current collector shown in Fig. 24. Note that the case body 110 is omitted from Fig. 23.

[0135] As shown in FIGS. 15 and 22 to 25, 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).

[0136] 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. Note that the connection of the plate-like member 304 to the positive electrode terminal 302 may be made at any time.

[0137] 25, the current collector 420 (first member) has a first region 10 extending along the sealing plate 130, a second region 20 extending in a direction perpendicular to the sealing plate 130, and an intermediate portion 15 (first folded portion) located between the first region 10 and the second region 20. The current collector 450 (second member) has a third region 30 extending along the sealing plate 130, a fourth region 40 extending in a direction perpendicular to the sealing plate 130, and an intermediate portion 35 (second folded portion) located between the third region 30 and the fourth region 40. The second region 20 and the fourth region 40 extend from the ends of the first region 10 and the third region 30 toward the electrode body 200.

[0138] In the example of Figure 25, the current collectors 420, 450 are bent at approximately right angles at the intermediate portions 15, 35, respectively. However, the bending angle of the current collectors 420, 450 is not limited to 90°. Preferably, a bending angle of approximately 45° to 135° can be used. Note that notches may be provided at both ends of the bent portion of the current collectors 420, 450 in the width direction (Y direction) to facilitate the bending process. The bent portion may include a rounded portion.

[0139] The first region 10 of the current collector 420 and the third region 30 of the current collector 450 are arranged to overlap. The first region 10 is located closer to the electrode body 200 than the third region 30. The positive electrode tab groups 250, 280 are connected to the first region 10 of the current collector 420.

[0140] The first region 10 and the third region 30 need only overlap when viewed in the X direction, and do not necessarily have to abut. However, it is preferable that the first region 10 and the third region 30 are disposed relatively close to each other, and for example, the gap between them is preferably about 5.0 mm or less, more preferably about 3.0 mm or less, and even more preferably about 1.0 mm or less.

[0141] When viewed from the X direction perpendicular to the sealing plate 130, the area of ​​the overlapping portion between the first region 10 and the third region 30 is 100 mm 2 It is preferable that the area of ​​the third region 30 is approximately 50% or more, and more preferably approximately 70% or more, of the area of ​​the third region 30. When viewed from the X direction, the area of ​​the third region 30 can be larger than the area of ​​the first region 10. Here, the area of ​​the overlapping portion between the first region 10 and the third region 30 is preferably approximately 50% or more, and more preferably approximately 70% or more, of the area of ​​the third region 30. An insulating member may be provided between the first region 10 and the third region 30. The insulating member provided between the first region 10 and the third region 30 may be formed, for example, from an insulating tape or a resin plate.

[0142] A fuse portion consisting of a through-hole, a thin portion (groove), a notch, or the like may be formed in current collector 420 or current collector 450. This allows the fuse portion to melt and cut off the current when an external short circuit or the like occurs. The fuse portion may be provided in any of first region 10, second region 20, third region 30, and fourth region 40.

[0143] The second region 20 of the current collector 420 and the fourth region 40 of the current collector 450 are arranged to overlap each other, thereby forming a contact region R11 where the current collector 420 and the current collector 450 overlap each other.

[0144] The current collector 420 and the current collector 450 are electrically connected to each other via a connecting member 460 (third member). The connecting member 460 is made of, for example, a conductive wire or a conductive ribbon. That is, the current collector 420 and the current collector 450 can be electrically connected by wire bonding or ribbon bonding. The current collectors 420 and 450 can be connected to the connecting member 460 by, for example, ultrasonic bonding.

[0145] 24, 25 and the figures described below, the number, shape and connection positions of connecting members 460 that connect current collectors 420 and 450 can be changed as appropriate.

[0146] When current collector 420 and current collector 450 are joined to each other by laser welding, high-energy laser light is irradiated onto at least one of current collector 420 and current collector 450 located in contact region R11 from between sealing plate 130 and the end of case body 110 on the opening 114 side, and current collector 420 and current collector 450 are welded together at welding position P1 in contact region R11.

[0147] In this case, laser welding must be performed in a small area, which may make it difficult to provide a dust collection mechanism. Furthermore, it is difficult to control the direction of spatter scattering during laser welding, which may allow foreign matter to enter case body 110. Furthermore, reflected laser light may affect insulating member 530. From another perspective, the required accuracy of the relative positioning of current collector 420 and current collector 450 becomes higher.

[0148] In contrast, in secondary battery 1 according to the present embodiment, irradiation of high-energy rays (laser welding) for directly connecting base materials (current collector 420 and current collector 450) is not required, and therefore it is possible to stably electrically connect the current collecting parts while suppressing dust generation. Furthermore, it is possible to suppress the influence of reflected laser light on insulating member 530, and to suppress the requirement for the accuracy of positioning current collector 420 and current collector 450 relative to each other from becoming too high.

[0149] As described above, according to this embodiment, a highly reliable secondary battery 1 can be obtained while suppressing a decrease in manufacturing efficiency.

[0150] The connection between the current collectors on the sealing plate 120 side (negative electrode side) can be configured in the same manner as the connection between the current collectors on the sealing plate 130 side (positive electrode side). Furthermore, the current collector 420 on the sealing plate 130 side (positive electrode side) may be configured as multiple (two) separate members, like the current collectors 410, 430 on the sealing plate 120 side (negative electrode side).

[0151] As shown in Fig. 23, 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 Figs. 23 to 25, 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. 14, 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.

[0152] 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.

[0153] Fig. 26 is a perspective view showing the configuration of the secondary battery according to embodiment 1. As shown in Figs. 15 and 26, next, sealing plates 120 and 130 are joined to case body 110 (step S10). Sealing plate 120 seals opening 113 of case body 110, and sealing plate 130 seals opening 114 of case body 110. As a result, first electrode body 201 and second electrode body 202 are housed in case 100.

[0154] 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.

[0155] The order of the electrode assembly 200 insertion step and the current collector connection step is not limited to the above example. For example, after only a portion of the electrode assembly 200 is inserted into the case body 110 (first step) so that the end of the negative electrode active material layer 212 (second electrode active material layer) on the opening 113 side is disposed outside the case body 110, the negative electrode terminal 301 (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 assembly 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 assembly 200 may be electrically connected during the step of inserting the electrode assembly 200 into the case body 110.

[0156] In this embodiment, by providing the first electrode body 201 with a negative electrode tab group 220 and a positive electrode tab group 250 and the second electrode body 202 with a negative electrode tab group 270 and a positive electrode tab group 280, a configuration can be achieved in which the first electrode body 201 and the second electrode body 202 have separate electrode tabs. This configuration allows the electrode tabs to be shorter than when the first electrode body 201 and the second electrode body 202 form a single electrode tab and then bend the electrode tab. As a result, the volume occupied by the electrode tabs can be reduced, thereby improving the energy density of the secondary battery 1. Furthermore, the configuration in which the first electrode body 201 and the second electrode body 202 have separate electrode tabs makes it easier to bend the electrode tabs than when the first electrode body 201 and the second electrode body 202 form a single electrode tab. This facilitates joining the electrode tabs to the current collector, 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 collector.

[0157] The following describes secondary batteries according to embodiments 2 to 7. Regarding the secondary batteries according to embodiments 2 to 7, the description of the configurations that are similar to those of secondary battery 1 according to embodiment 1 and the configurations that are similar among embodiments 2 to 7 will not be repeated.

[0158] In embodiments 2 to 7, the connection between current collectors on the sealing plate 130 side is described, but the connection between current collectors on the sealing plate 120 side can also be configured in the same way as the connection between current collectors on the sealing plate 130 side.

[0159] (Embodiment 2) Fig. 27 is a cross-sectional view showing the configuration of a secondary battery according to embodiment 2. As shown in Fig. 27, in the secondary battery according to embodiment 2, tip portions 222A, 272A of negative electrode tab group 220A and negative electrode tab group 270A are bent in the same direction in the Y direction.

[0160] Thereafter, the first electrode body 201A and the second electrode body 202A are inserted into the case body, and the sealing plate 120 is abutted against the case body. As a result, the negative electrode tab group 220A and the negative electrode tab group 270A are curved in the same direction so that the tip portions 222A and 272A face in the same direction. To make it easier to curve the tip portions 222A and 272A in the same direction, the third component 630A of the spacer 600A is provided between the negative electrode tab group 220A and the negative electrode tab group 270A.

[0161] By making the tip portions 222A, 272A of the negative electrode tab group 220A and the negative electrode tab group 270A curved in the same direction in the Y direction, it is possible to prepare the first electrode body 201 to which the current collector 410 is attached and the second electrode body 202 to which the current collector 430 is attached, with the same configuration. This makes it possible to configure the first electrode body 201 to which the current collector 410 is attached and the second electrode body 202 to which the current collector 430 is attached as one type, thereby simplifying the manufacturing process.

[0162] (Embodiment 3) Fig. 28 is a perspective view showing the configuration of a current collector included in a secondary battery according to Embodiment 3. Fig. 29 is a cross-sectional view taken along line XXIX-XXIX of the current collector shown in Fig. 28.

[0163] 29, current collector 420B (first member) has a first region 10B extending along sealing plate 130, a second region 20B extending in a direction intersecting sealing plate 130, and an intermediate portion 15B (first folded portion) located between first region 10B and second region 20B. Current collector 450B (second member) has a third region 30B extending along sealing plate 130, a fourth region 40B extending in a direction intersecting sealing plate 130, and an intermediate portion 35B (second folded portion) located between third region 30B and fourth region 40B.

[0164] The first region 10B of the current collector 420B and the third region 30B of the current collector 450B are arranged to overlap. The first region 10B is located closer to the electrode assembly 200 than the third region 30B. The positive electrode tab groups 250, 280 are connected to the first region 10B of the current collector 420B.

[0165] The second region 20B of the current collector 420B and the fourth region 40B of the current collector 450B are substantially L-shaped. The second region 20B and the fourth region 40B are folded back so as to be inclined from the YZ plane and protrude toward the case body 110.

[0166] The second region 20B constitutes a first protruding region that protrudes further toward the electrode body 200 than the first region 10B, and the fourth region 40B constitutes a second protruding region that protrudes further toward the electrode body 200 than the third region 30B. The second region 20B and the fourth region 40B are arranged to overlap each other, thereby forming a contact region R31 where the current collector 420B and the current collector 450B overlap each other.

[0167] The end (tip) of the fourth region 40B (second protruding region) farther from the third region 30B is in contact with the insulating member 530.

[0168] In the first region 10B and the third region 30B, a gap G1 is preferably provided between the current collector 420B and the current collector 450B. This facilitates preferential contact between the current collectors in the contact region R31. Furthermore, the reaction force generated when the electrode tab is bent acts on the current collector 420B, thereby bringing the current collector 420B and the current collector 450B into close contact with each other. The size of the gap G1 (in the X direction) is preferably approximately 2.0 mm or less, and more preferably approximately 1.0 mm or less.

[0169] Current collector 420B and current collector 450B can be electrically connected by wire bonding or ribbon bonding using connecting member 460 (third member). In secondary battery 1 according to the present embodiment, irradiation of high-energy rays (laser welding) for directly connecting base materials (current collector 420B and current collector 450B) to each other is also unnecessary, and therefore, similar to embodiment 1, a highly reliable secondary battery 1 can be obtained while suppressing a decrease in manufacturing efficiency.

[0170] (Fourth embodiment) Fig. 30 is a perspective view showing the structure of a current collector included in a secondary battery according to embodiment 4. Fig. 31 is a cross-sectional view taken along line XXXI-XXXI of the current collector shown in Fig. 30.

[0171] 31, current collector 420C (first member) has first region 10C and second region 20C extending along sealing plate 130, and intermediate portion 15C located between first region 10C and second region 20C. Current collector 450C (second member) has third region 30C and fourth region 40C extending along sealing plate 130, and intermediate portion 35C located between third region 30C and fourth region 40C.

[0172] In the first region 10C of the current collector 420C and the fourth region 40C of the current collector 450C, a contact region R41 is formed where the current collector 420C and the current collector 450C come into contact with each other in the first direction (X direction).

[0173] The contact region R41 includes the contact surface between the current collector 420C and the current collector 450C. The contact region R41 extends on a plane intersecting the first direction (X direction). The contact region R41 extends in both the Y direction and the Z direction. The contact region R41 is preferably disposed along the sealing plate 130.

[0174] The size of the gap G2 (X direction) is preferably, for example, about 0.1 mm or more, more preferably about 0.5 mm or more, and even more preferably about 1.0 mm or more. The size of the gap G2 (X direction) is preferably, for example, about 5.0 mm or less, more preferably about 2.0 mm or less, and even more preferably about 1.0 mm or less.

[0175] In the present embodiment as well, current collector 420C and current collector 450C can be electrically connected by wire bonding or ribbon bonding using connection member 460 (third member).

[0176] (Embodiment 5) Fig. 32 is a perspective view showing the configuration of a current collector included in a secondary battery according to embodiment 5. Fig. 33 is a cross-sectional view taken along line XXXIII-XXXIII of the current collector shown in Fig. 32.

[0177] 33, current collector 420D (first member) has a first region 10D extending along sealing plate 130, a second region 20D, and an intermediate portion 15D located between first region 10D and second region 20D. Current collector 450D (second member) has a third region 30D extending along sealing plate 130, a fourth region 40D, and an intermediate portion 35D located between third region 30D and fourth region 40D.

[0178] In the second region 20D of the current collector 420D and the fourth region 40D of the current collector 450D, a contact region R51 is formed where the current collector 420D and the current collector 450D contact each other in the first direction (X direction).

[0179] At the end of the contact region R51, the current collector 420D and the current collector 450D are bent in a direction away from each other. The contact region R51 includes the contact surface between the current collector 420D and the current collector 450D. The contact region R51 extends on a plane intersecting with the first direction (X direction). The contact region R51 extends in both the Y direction and the Z direction. The contact region R51 is preferably disposed along the sealing plate 130.

[0180] In the fourth region 40D, a gap G2 is provided between the current collector 450D and the insulating member 530.

[0181] In the present embodiment as well, current collector 420D and current collector 450D can be electrically connected by wire bonding or ribbon bonding using connection member 460 (third member).

[0182] (Embodiment 6) Fig. 34 is a perspective view showing the structure of a current collector included in a secondary battery according to Embodiment 6. Fig. 35 is a cross-sectional view taken along line XXXV-XXXV of the current collector shown in Fig. 34.

[0183] As shown in FIG. 35, current collector 450E (second member) in this embodiment is thicker in the X direction than current collector 420E (first member).

[0184] For example, the thickness of current collector 450E is preferably at least about 1.2 times, more preferably at least about 1.5 times, and even more preferably at least about 2.0 times the thickness of current collector 420E. Note that when comparing the thicknesses of the current collectors, it is preferable to compare the thickness of the base portion (a portion of normal thickness where no irregularities are formed) of each current collector.

[0185] Current collector 420E is provided with fuse portion 422E. When the current collector generates excessive heat, the current collector melts preferentially at fuse portion 422E, which is the part of the positive electrode current collector that is as far away from the insulating member as possible.

[0186] In the present embodiment, similarly to the fifth embodiment, a separation portion where current collector 420E and current collector 450E are separated is formed at the end of contact region R61.

[0187] In the present embodiment as well, current collector 420E and current collector 450E can be electrically connected by wire bonding or ribbon bonding using connection member 460 (third member).

[0188] (Embodiment 7) FIG. 36 is a cross-sectional view showing the structure of a current collector included in the secondary battery according to the seventh embodiment.

[0189] 36, current collector 420F (first member) has first region 10F and second region 20F extending along sealing plate 130, and intermediate portion 15F located between first region 10F and second region 20F. Current collector 450F (second member) has third region 30F and fourth region 40F extending along sealing plate 130, and intermediate portion 35F located between third region 30F and fourth region 40F.

[0190] In the second region 20F of the current collector 420F and the fourth region 40F of the current collector 450F, a contact region R71 is formed where the current collector 420F and the current collector 450F contact each other in the first direction (X direction). The thickness of the current collector 450F is greater than the thickness of the current collector 420F. When comparing the thicknesses of the current collectors, it is preferable to compare the thicknesses of the base portions (parts of normal thickness where no irregularities are formed) of the current collectors.

[0191] In the present embodiment, similarly to the fifth and sixth embodiments, a separation portion where current collector 420F and current collector 450F are separated from each other is formed at the end of contact region R71.

[0192] The contact region R71 includes the contact surface between the current collector 420F and the current collector 450F. The contact region R71 extends on a plane intersecting the first direction (X direction). The contact region R71 extends in both the Y direction and the Z direction. The contact region R71 is preferably disposed along the sealing plate 130.

[0193] In the fourth region 40F, a gap G2 is formed between the current collector 450F and the insulating member 530.

[0194] In the present embodiment as well, current collector 420E and current collector 450E can be electrically connected by wire bonding or ribbon bonding using connection member 460 (third member).

[0195] Preferably, each of the sealing plates 120 and 130 has a pair of long sides that are parallel to each other and a pair of short sides that are shorter than the pair of long sides that are parallel to each other. Here, the direction in which the long sides extend is the longitudinal direction.

[0196] (Configuration example of connection member 460) Next, configuration examples of connection member 460 (third member) will be described with reference to Fig. 37 to Fig. 42. Fig. 37 (top view) and Fig. 38 (side view) show a first example, Fig. 39 (top view) and Fig. 40 (side view) show a second example, and Fig. 41 (top view) and Fig. 42 (side view) show a third example.

[0197] In the example shown in FIGS. 37 and 38, a plurality of connection members 460 (wires or ribbons) are arranged at equal intervals.

[0198] 39 and 40, multiple connection members 460 (ribbons) are also arranged at equal intervals, but the intervals are greater than in the examples of Figures 37 and 38. In the examples of Figures 39 and 40, multiple layers (for example, two to five layers) of connection members 460 (ribbons) are stacked.

[0199] In the example of FIGS. 41 and 42, the connection member 460 (wire or ribbon) is formed into a loop shape.

[0200] As described above, various modes can be adopted for the connecting member 460. The scope of the present technology is not limited to the examples shown in FIGS.

[0201] The connecting member 460 may be made of a single member or multiple members. By configuring the connecting member 460 from a single member, the processing cycle time and manufacturing costs can be reduced. By configuring the connecting member 460 from multiple members, the degree of freedom in the shape of the connecting member 460 is increased and connection with low energy is possible. In addition, the jig used for joining can be made smaller.

[0202] Since the connection member 460 serves as an electrical conduction path, it is preferable that the connection member 460 has a conduction area that can accommodate a predetermined rapid charge. For example, it is preferable that the connection member 460 has a conduction area that can tolerate charging at approximately 1 C (more preferably, approximately 4 C). "1 C equivalent" can be defined as the magnitude of current that fully charges (or discharges) the theoretical capacity of the battery in one hour. "4 C equivalent" can be defined as a current that is "four times" that of "1 C equivalent" (one-quarter the charge / discharge time).

[0203] When the connection member 460 is made of a wire (linear member), as an example, the wire diameter can be approximately φ18 μm or more and 80 μm or less, the material can be aluminum or copper, the number can be approximately 1 to 3,000, and the pitch when arranged at equal intervals can be approximately 0.5 mm to 2.5 mm.

[0204] When the connection member 460 is formed using a ribbon (strip-shaped member), as an example, the width of the ribbon (approximately rectangular cross section) can be approximately 100 μm or more and 2000 μm or less, the thickness can be approximately 20 μm or more and 500 μm or less, the material can be aluminum or copper, the number can be approximately 1 to 50, the pitch when arranged at equal intervals can be approximately 0.5 mm to 2.5 mm, and the number of layers can be approximately 1 to 5.

[0205] The above-mentioned numerical values ​​are merely examples, and the scope of the present technology is not limited to these.

[0206] In the examples of the first to seventh embodiments described above, the configuration of the connecting member 460 in the positive electrode current collector 400B has been described, but the connecting configuration using the connecting member 460 can also be provided in the negative electrode current collector 400A. The connecting configuration using the connecting member 460 may be applied to both the negative electrode current collector 400A and the positive electrode current collector 400B, or the connecting configuration using the connecting member 460 may be applied to only one of the negative electrode current collector 400A and the positive electrode current collector 400B.

[0207] 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]

[0208] 1 Secondary battery, 10,10B,10C,10D,10F 1st area, 15,15B,15C,15D,15F,35,35B,35C,35D,35F Middle part, 20,20B,20C,20D,20F 2nd area, 30,30B,30C,30D,30F 3rd area, 40,40B,40C,40D,40F 4th area, 100 case, 110 case body, 111 1st side part, 112,112A,112B 2nd side part, 113,114 opening, 115 joint, 120,130 sealing plate, 134 liquid injection hole, 150 gas discharge valve, 200,200A Electrode body, 201,201A First electrode body, 202, 202A Second electrode body, 205 First end, 206 Second end, 207 Third end, 208 Fourth end, 210 Negative electrode plate, 210S Negative electrode base plate, 211 Negative electrode core, 212 Negative electrode active material layer, 220, 220A, 270, 270A Negative electrode tab group, 221, 271 Curved portion, 222, 222A, 272, 272A Tip portion, 230 Negative electrode tab, 240 Positive electrode plate, 240S Positive electrode base plate, 241 Positive electrode core, 242 Positive electrode active material layer, 243 Positive electrode protective layer, 250, 280 Positive electrode tab group, 251, 281 Curved portion, 252, 282 Tip portion, 260 Positive electrode tab, 300 Electrode terminal, 301 negative electrode terminal, 302 positive electrode terminal, 303, 304 plate-shaped members, 400, 410, 420, 420B, 420C, 420D, 420E, 420F, 430, 440, 450, 450B, 450C, 450D, 450E, 450F current collector, 400A negative electrode current collector, 400B positive electrode current collector, 411, 421, 431 joint portion, 422E fuse portion, 460 connection member, 510, 520, 530 insulating member, 600, 600A spacer, 610 first part, 620 second part, 630A third part, 700 insulating sheet.

Claims

1. an electrode assembly including a positive electrode and a negative electrode; a case that houses the electrode assembly and includes a case body having an opening and a sealing plate that seals the opening; an electrode terminal provided on the outer surface of the sealing plate; a current collecting portion that electrically connects the electrode body and the electrode terminal, The current collecting portion is a conductive first member joined to the electrode body; a conductive second member fixed on the inner surface of the sealing plate and joined to the electrode terminal; a conductive third member that is separate from the first member and the second member and electrically connects the first member and the second member;

2. The secondary battery according to claim 1 , wherein the third member is a conductive linear member or a strip-shaped member.

3. 3. The secondary battery according to claim 1, wherein the case has a substantially rectangular parallelepiped shape.

4. the case body has a first opening and a second opening located on both sides in a first direction, the sealing plate includes a first sealing plate and a second sealing plate that seal the first opening and the second opening, respectively; the electrode terminals include a positive electrode terminal or a negative electrode terminal provided on an outer surface of one of the first sealing plate and the second sealing plate, 3. The secondary battery according to claim 1, wherein the current collecting portion is provided between the electrode body and the positive electrode terminal or the negative electrode terminal.

5. 3. The secondary battery according to claim 1, wherein the third member has a conductive area capable of allowing charging equivalent to 1 C.

6. 3. The secondary battery according to claim 1, wherein the third member is made of a single member.

7. 3. The secondary battery according to claim 1, wherein the third member is made up of a plurality of members.

8. a step of inserting an electrode assembly including a positive electrode and a negative electrode into the case body through the opening; providing an electrode terminal on an outer surface of the sealing plate; sealing the opening with the sealing plate; electrically connecting the electrode body and the electrode terminal via a current collecting portion, The step of electrically connecting the electrode body and the electrode terminal includes: joining a conductive first member to the electrode body; a conductive second member is fixed on the inner surface of the sealing plate and joined to the electrode terminal; and electrically connecting the first member and the second member via a conductive third member made of a material separate from the first member and the second member.

9. The method for manufacturing a secondary battery according to claim 8 , wherein the third member is made of a conductive linear member or a strip-shaped member.

10. The method for manufacturing a secondary battery according to claim 8 or 9, wherein the case consisting of the case body and the sealing plate has a substantially rectangular parallelepiped shape.

11. the case body has a first opening and a second opening located on both sides in a first direction, the sealing plate includes a first sealing plate and a second sealing plate that seal the first opening and the second opening, respectively; the electrode terminals include a positive electrode terminal or a negative electrode terminal provided on an outer surface of one of the first sealing plate and the second sealing plate, 10. The method for manufacturing a secondary battery according to claim 8, wherein the current collecting portion is provided between the electrode body and the positive electrode terminal or the negative electrode terminal.

12. The method for manufacturing a secondary battery according to claim 11 , wherein the first member and the second member are electrically connected via the third member after the electrode body is inserted into the case body.

13. The method for manufacturing a secondary battery according to claim 8 or 9, wherein the third member has a conductive area capable of allowing charging equivalent to 1 C.

14. 10. The method for manufacturing a secondary battery according to claim 8, wherein the third member is made of a single member.

15. 10. The method for manufacturing a secondary battery according to claim 8, wherein the third member is made up of a plurality of members.

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