Secondary battery and method for manufacturing the same

Abstract

To provide a secondary battery with high energy density and high reliability.SOLUTION: In a secondary battery, a first current collector member includes a first region extending along a first wall, a second region extending in a direction intersecting with the first wall, and a first bent part provided between the first region and the second region. A second current collector member includes a third region extending along the first wall, a fourth region extending in a direction intersecting with the first wall, and a second bent part provided between the third region and the fourth region. The first region and the third region are disposed overlapping with each other. The first region exists on an electrode body side relative to the third region. A first electrode tab is connected to the first region. The second region and the fourth region are bonded together.SELECTED DRAWING: Figure 25

Description

Technical Field

[0001] This technology relates to secondary batteries.

Background Art

[0002] Japanese Patent Publication No. 4537353 (Patent Document 1) discloses 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 respectively attached to cap plates (33, 33') that seal the openings (14a, 14b).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] There is a need to improve the energy density and reliability of secondary batteries. From these viewpoints, there is still room for improvement in the secondary battery described in Patent Document 1.

[0005] An object of this technology is to provide a secondary battery having a high energy density and high reliability.

Means for Solving the Problems

[0006] This technology provides the following secondary battery.

[0007] [1] A secondary battery comprising an electrode body including a first electrode, a second electrode having a different polarity from the first electrode, and a first electrode tab electrically connected to the first electrode; a case including a first wall for housing the electrode body; a first current collector member electrically connected to the first electrode tab; and a second current collector member connected to the first current collector member, wherein the first current collector member has a first region extending along the first wall, a second region extending in a direction intersecting the first wall, and a first bent portion provided between the first region and the second region; the second current collector member has a third region extending along the first wall, a fourth region extending in a direction intersecting the first wall, and a second bent portion provided between the third region and the fourth region, wherein the first region and the third region are arranged on top of each other, the first region is located closer to the electrode body than the third region, the first electrode tab is connected to the first region, and the second region and the fourth region are joined together.

[0008] [2] The case includes a second wall opposite to the first wall, a first electrode tab is provided at the end of the electrode body on the first wall side, and a group of electrode tabs electrically connected to the second electrode is provided at the end of the electrode body on the second wall side, the secondary battery comprises a plurality of third current collectors each electrically connected to the group of electrode tabs, a fourth current collector connected to each of the plurality of third current collectors, and a second electrode terminal electrically connected to the fourth current collector and provided on the second wall, the group of electrode tabs includes a first tab connected to one of the plurality of third current collectors and a second tab connected to one of the plurality of third current collectors, the secondary battery according to claim 1.

[0009] [3] The secondary battery according to [2], wherein each of the plurality of third current collector members has a fifth region extending along the second wall, a sixth region extending in a direction intersecting the second wall, and a third bent portion provided between the fifth region and the sixth region, and the fourth current collector member has a seventh region extending along the second wall, an eighth region extending in a direction intersecting the second wall, and a fourth bent portion provided between the seventh region and the eighth region, the fifth region and the seventh region are arranged on top of each other, the fifth region is located closer to the electrode body than the seventh region, the electrode tab group is connected to the fifth region, and the sixth region and the eighth region are joined together.

[0010] [4] The secondary battery according to [2] or [3], wherein the fourth current collector member consists of a single member, and each of the plurality of third current collector members is joined to the single fourth current collector member.

[0011] [5] The secondary battery according to any one of [1] to [4], wherein the second current collector member consists of a single member and the first current collector member is joined to the single second current collector member.

[0012] [6] The secondary battery according to any one of [1] to [5], wherein at least one of the first current collector and the second current collector has a thin-walled portion that is relatively thin compared to its surroundings, and the first current collector and the second current collector are joined to each other at the thin-walled portion.

[0013] [7] A secondary battery according to any one of [1] to [6], wherein a resin member is arranged between the joint of the first current collector and the second current collector and the main body of the electrode body in a direction perpendicular to the first wall.

[0014] [8] The secondary battery according to any one of [1] to [7], wherein the second region extends from the end of the first region toward the electrode body, and the fourth region extends from the end of the third region toward the electrode body. [9] The secondary battery according to any one of [1] to [7], wherein the second region has a first protruding region that protrudes toward the electrode body more than the first region, and the fourth region has a second protruding region that protrudes toward the electrode body more than the third region, and the first protruding region and the second protruding region are arranged to overlap and the first protruding region and the second protruding region are joined together.

[0015]

[10] The secondary battery according to [9], wherein an insulating member is disposed between the first wall and the second current collector, and in the second protruding region, the end furthest from the third region is in contact with the insulating member.

[0016]

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

[10] , wherein the first region is located on the third region via an insulating member.

[0017]

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

[11] , wherein at least one of the first current collector and the second current collector is provided with a fuse.

[0018]

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

[12] , wherein the case includes a case body, a first sealing plate, and a second sealing plate, the case body having a first opening and a second opening provided at positions opposite to each other, the first opening being sealed by the first sealing plate, the second opening being sealed by the second sealing plate, the first sealing plate being provided with a first electrode terminal electrically connected to the first electrode, the second sealing plate being provided with a second electrode terminal electrically connected to the second electrode, the first wall being the first sealing plate, the electrode body having a group of first electrode tabs electrically connected to the first electrode at the end on the first sealing plate side, and the electrode body having a group of second electrode tabs electrically connected to the second electrode at the end on the second sealing plate side. [Effects of the Invention]

[0019] This technology makes it possible to provide a secondary battery with high energy density and high reliability, as well as a method for manufacturing a secondary battery.

Brief Description of the Drawings

[0020] [Figure 1] It is a front view showing the configuration of the secondary battery according to Embodiment 1. [Figure 2] It is a view showing the state of the secondary battery shown in FIG. 1 as viewed from the direction of arrow II. [Figure 3] It is a view showing the state of the secondary battery shown in FIG. 1 as viewed from the direction of arrow III. [Figure 4] It is a view showing the state of the secondary battery shown in FIG. 1 as viewed from the direction of arrow IV. [Figure 5] It is a view showing the state of the secondary battery shown in FIG. 1 as viewed from the direction of arrow V. [Figure 6] It is a front cross-sectional view of the secondary battery shown in FIG. 1. [Figure 7] It is a front view showing the negative electrode raw plate before the negative electrode plate is formed. [Figure 8] It is a cross-sectional view taken along line VIII-VIII of the negative electrode raw plate shown in FIG. 7. [Figure 9] It is a front view showing the negative electrode plate formed from the negative electrode raw plate. [Figure 10] It is a front view showing the positive electrode raw plate before the positive electrode plate is formed. [Figure 11] It is a cross-sectional view taken along line XI-XI of the positive electrode raw plate shown in FIG. 10. [Figure 12] It is a front view showing the positive electrode plate formed from the positive electrode raw plate. [Figure 13] It is a cross-sectional view taken along line XIII-XIII of the secondary battery shown in FIG. 1. [Figure 14] It is a cross-sectional view taken along line XIV-XIV of the secondary battery shown in FIG. 1. [Figure 15] It is a flowchart showing the manufacturing method of the secondary battery according to Embodiment 1. [Figure 16] It is a perspective view showing the state before the two electrode bodies included in the secondary battery according to Embodiment 1 overlap. [Figure 17] It is a cross-sectional view taken along line XVII-XVII of the electrode body and current collector shown in FIG. 16. [Figure 18]This is a perspective view showing the electrode body with the holder and spacer attached. [Figure 19] This is a perspective view showing the negative electrode current collector with a sealing plate attached. [Figure 20] Figure 19 is a cross-sectional view of the electrode body and current collector along line XX-XX. [Figure 21] This is a perspective view showing the electrode body inserted into the case. [Figure 22] This is a perspective view showing the positive electrode current collector with a sealing plate attached. [Figure 23] Figure 22 is a cross-sectional view of the electrode body and current collector along line XXIII-XXIII. [Figure 24] Figure 22 shows the current collector as viewed from the direction of arrow XXIV. [Figure 25] Figure 24 is a cross-sectional view of the current collector along the XXV-XXV line. [Figure 26] This is a cross-sectional view of the negative electrode current collector corresponding to Figure 25. [Figure 27] This is a perspective view showing the configuration of the secondary battery according to Embodiment 1. [Figure 28] This is a cross-sectional view showing the configuration of a secondary battery according to Embodiment 2. [Figure 29] This is a perspective view showing the configuration of the current collector in the secondary battery according to Embodiment 3. [Figure 30] Figure 29 is a cross-sectional view of the current collector along the line XXX-XXX. [Figure 31] This is a cross-sectional view of the negative electrode current collector corresponding to Figure 30. [Modes for carrying out the invention]

[0021] Embodiments of this technology are described below. Note that the same or corresponding parts may be denoted by the same reference numerals, and their descriptions may not be repeated.

[0022] In the embodiments described below, when referring to the number, quantity, etc., unless otherwise specified, the scope of this technology is not necessarily limited to that number, quantity, etc. Also, in the embodiments described below, each component is not necessarily essential to this technology unless otherwise specified. Furthermore, this technology is not necessarily limited to achieving all of the effects and advantages mentioned in these embodiments.

[0023] In this specification, the terms "comprise," "include," and "have" are in open-ended form. That is, if a configuration includes one configuration, it may also include other configurations, or it may not.

[0024] Furthermore, where geometric terms and terms describing positional and directional relationships are used in this specification, such as "parallel," "orthogonal," "45° oblique," "coaxial," and "alongside," these terms allow for manufacturing tolerances or slight variations. Where terms describing relative positional relationships, such as "upper" and "lower," are used in this specification, these terms are used to indicate the relative positional relationship in a single state, and the relative positional relationship may be reversed or rotated to any angle depending on the installation direction of each mechanism (for example, by inverting the entire mechanism upside down).

[0025] In this specification, “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, “electrode” may refer collectively to the positive electrode and the negative electrode.

[0026] In the drawings, the direction along the winding axis of the electrode body of the secondary battery is defined as the X direction, the short side of the electrode body as viewed from the X direction is defined as the Y direction, and the long side of the electrode body as viewed from the X direction is defined as the Z direction. Furthermore, in order to facilitate understanding of the invention, the dimensions of each component in the drawings have been altered from the actual dimensions in some cases.

[0027] In this specification, the first direction (X direction) may be referred to as the "width direction" of the secondary battery or case body, the second direction (Y direction) may be referred to as the "thickness direction" of the secondary battery or case body, and the third direction (Z direction) may be referred to as the "height direction" of the secondary battery or case body.

[0028] (Embodiment 1) The secondary battery 1 according to Embodiment 1 will be described below.

[0029] (Overall battery configuration) Figure 1 is a front view of the secondary battery 1 according to this embodiment. Figures 2 to 5 show the secondary battery 1 shown in Figure 1 as viewed from the directions of arrows II, III, IV, and V, respectively. Figure 6 is a front cross-sectional view of the secondary battery 1 shown in Figure 1.

[0030] The secondary battery 1 can be installed in electric vehicles (BEVs), plug-in hybrid electric vehicles (PHEVs), and hybrid electric vehicles (HEVs), etc. However, the use of the secondary battery 1 is not limited to automotive applications.

[0031] As shown in Figures 1 to 6, the secondary battery 1 includes a case 100, an electrode body 200, electrode terminals 300, and a current collector 400. The case 100 includes a case body 110, a sealing plate 120, and a sealing plate 130.

[0032] When a battery pack including a secondary battery 1 is constructed, multiple secondary batteries 1 are stacked in the thickness direction. The stacked secondary batteries 1 may be constrained in the stacking direction (Y direction) by a restraining member to form a battery module, or the battery pack may be directly supported on the side of the battery pack case without using a restraining member.

[0033] The case body 110 consists 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, aluminum alloy, iron, or iron alloy.

[0034] As shown in Figures 1 and 2, sealing plates 120 (second wall) and 130 (first wall) are provided at both ends of the case body, respectively. The case body 110 can be formed into a rectangular tube shape by, for example, bringing together the ends of bent plate-like members (joint portion 115 as illustrated in Figure 2) and joining them together (for example, by laser welding). The corners of the "rectangular tube" may have a rounded shape.

[0035] In this embodiment, the case body 110 is formed to be 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 makes it possible to construct 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 makes it possible to construct a relatively low-height secondary battery 1, which improves, for example, its mountability in a vehicle.

[0036] The case body 110 includes a pair of first side sections 111 and a pair of second side sections 112. The pair of first side sections 111 constitute a part of the side surface of the case 100. The pair of second side sections 112 constitute the bottom and top surfaces of the case 100. Each of the pair of first side sections 111 and the pair of second side sections 112 is provided so as to intersect each other. The pair of first side sections 111 and the pair of second side sections 112 are connected at their respective ends. It is desirable that each of the pair of first side sections 111 has a larger area than each of the pair of second side sections 112.

[0037] As shown in Figure 5, a gas exhaust valve 150 is provided on one of the pair of second side portions 112A. The gas exhaust valve 150 extends in the width direction (X direction) of the secondary battery 1. The gas exhaust valve 150 extends in the X direction to the extent that it does not reach the ends of the case body 110 from the center in the X direction. The gas exhaust valve 150 can be modified as appropriate.

[0038] The thickness of the plate-shaped member in the gas discharge valve 150 is thinner than the thickness of the other plate-shaped members in the case body 110. As a result, when the pressure inside the case 100 exceeds a predetermined value, the gas discharge valve 150 preferentially ruptures compared to other parts of the case body 110, and discharges the gas inside the case 100 to the outside.

[0039] As shown in Figure 2, a joint portion 115 is formed on the other second side portion 112B of the pair of second side portions 112. The joint portion 115 extends in the width direction (X direction) of the secondary battery 1. At the joint portion 115, the ends of the plate-shaped members constituting the case body 110 are joined together.

[0040] As shown in Figure 3, an opening 113 (second opening) is provided at the first side end of the case body 110 in the first direction (X direction). The opening 113 is sealed by a sealing plate 120. A joint 115 is formed in the opening 113 to seal it. The opening 113 and the sealing plate 120 have a substantially rectangular shape with the Y direction being the short side and the Z direction being the long side. Note that the substantially rectangular shape includes a rectangular shape, or a rectangular shape with rounded corners, etc.

[0041] A negative terminal 301 is provided on the sealing plate 120 (second sealing plate). The position of the negative terminal 301 can be changed as appropriate.

[0042] As shown in Figure 4, an opening 114 (first opening) is provided at the end of the second side of the case body 110 opposite to the first side in the first direction (X direction). That is, the opening 114 is located at the end opposite to the opening 113, and the openings 113 and 114 face each other. The opening 114 is sealed by a sealing plate 130. A joint 115 is formed in the opening 114 to seal it. The opening 114 and the sealing plate 130 have a substantially rectangular shape with the Y direction being the short side and the Z direction being the long side.

[0043] A positive electrode terminal 302 and an injection hole 134 are provided on the sealing plate 130 (first sealing plate). The positions of the positive electrode terminal 302 and the injection hole 134 can be changed as appropriate.

[0044] The sealing plates 120 and 130 are made of metal. Specifically, the sealing plates 120 and 130 are made of aluminum, aluminum alloy, iron, or iron alloy.

[0045] 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, i.e., the case 100.

[0046] The positive terminal 302 is electrically connected to the positive electrode of the electrode body 200. The positive terminal 302 is attached to the sealing plate 130, i.e., the case 100.

[0047] The negative electrode terminal 301 (first electrode terminal) is made of a conductive material (more specifically, a metal), such as copper or a copper alloy. A portion or layer made of aluminum or an aluminum alloy may be provided on the outer surface of the negative electrode terminal 301.

[0048] The positive terminal 302 is made of a conductive material (more specifically, a metal), which may be made of aluminum or an aluminum alloy, for example.

[0049] The injection hole 134 is sealed by a sealing member (not shown). For example, a blind rivet or other metal member can be used as the sealing member.

[0050] The electrode body 200 is a flat-shaped electrode body having a positive electrode plate and a negative electrode plate, which will be described later. Specifically, the electrode body 200 is a wound-type electrode body 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, "electrode body" is not limited to a wound-type electrode body, and may also be a laminated-type electrode body in which multiple positive electrode plates and multiple negative electrode plates are alternately stacked. The strip-shaped separator can be made of, for example, a polyolefin microporous film. The electrode body may include multiple positive electrode plates and multiple negative electrode plates, and positive electrode tabs provided on each positive electrode plate may be stacked to form a group of positive electrode tabs, or negative electrode tabs provided on each negative electrode plate may be stacked to form a group of negative electrode tabs. The electrode body 200 may include multiple wound-type electrode bodies, or it may include multiple laminated-type electrode bodies.

[0051] As shown in Figure 6, the case 100 houses the electrode body 200. In Figure 6, the first electrode body 201, which will be described later, is shown as an example. The first electrode body 201 is housed in the case 100 so that its winding axis is parallel to the X direction.

[0052] Specifically, one or more wound electrode bodies are housed inside the insulating sheet 700 (described later) placed within the case 100, together with an electrolyte (not shown). As the electrolyte (non-aqueous electrolyte), for example, a non-aqueous solvent prepared 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 LiPF6 is dissolved at a concentration of 1.2 mol / L can be used. Alternatively, a solid electrolyte may be used instead of the electrolyte.

[0053] The first electrode body 201 includes a main body (a portion in which a positive electrode plate and a negative electrode plate are stacked with a separator in between), a negative electrode tab group 220 (second electrode tab group), and a positive electrode tab group 250 (first electrode tab group).

[0054] 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 first side end of the first electrode body 201 in the 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 second side end 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.

[0055] The negative electrode tab group 220 and the positive electrode tab group 250 are formed to protrude from the central portion of the electrode body 200 toward the sealing plate 120 or the sealing plate 130, respectively.

[0056] The current collector 400 includes a negative electrode current collector 400A and a positive electrode current collector 400B. The negative electrode current collector 400A and the positive electrode current collector 400B are each made of plate-shaped members. The electrode body 200 is electrically connected to the negative electrode terminal 301 and the positive electrode terminal 302 via the current collector 400.

[0057] The negative electrode current collector 400A is positioned 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 copper or a copper alloy, for example. Further details of the negative electrode current collector 400A will be described later.

[0058] The positive electrode current collector 400B is positioned 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, 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 also function as the positive electrode terminal 302. Further details of the positive electrode current collector 400B will be described later.

[0059] (Configuration of electrode body 200) Figure 7 is a front view showing the negative electrode base plate 210S before the negative electrode plate 210 is formed, Figure 8 is a cross-sectional view of the negative electrode base plate 210S shown in Figure 7, and Figure 9 is a front view showing the negative electrode plate 210 formed from the negative electrode base plate 210S.

[0060] The negative electrode plate 210 is manufactured by processing the negative electrode base plate 210S. As shown in Figures 7 and 8, the negative electrode base 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 made of copper foil or copper alloy foil.

[0061] The negative electrode core body 211 has a negative electrode active material layer 212 formed on both sides, except for one end. The negative electrode active material layer 212 is formed by applying a negative electrode active material slurry using a die coater.

[0062] The negative electrode active material layer slurry is prepared by kneading graphite as the negative electrode active material, styrene-butadiene rubber (SBR) and carboxymethylcellulose (CMC) as binders, and water as a dispersion medium, so that the mass ratio of graphite:SBR:CMC is approximately 98:1:1.

[0063] The negative electrode core 211, to which the negative electrode active material layer slurry has been applied, is dried to remove water contained in the negative electrode active material layer slurry, thereby forming the negative electrode active material layer 212. Furthermore, by compressing the negative electrode active material layer 212, a negative electrode base plate 210S containing the negative electrode core 211 and the negative electrode active material layer 212 is formed. The negative electrode plate 210 is formed by cutting the negative electrode base plate 210S into a predetermined shape. The negative electrode base plate 210S can be cut by laser processing using energy beam irradiation, mold processing, or cutter processing.

[0064] As shown in Figure 9, a plurality of negative electrode tabs 230 (second electrode tabs) made of a negative electrode core 211 are provided at one end in the width direction of the negative electrode plate 210 formed from the negative electrode base 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 protruding length of each of the plurality of negative electrode tabs 230 are appropriately adjusted considering 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 tabs 230 is not limited to that illustrated in Figure 8.

[0065] Figure 10 is a front view showing the positive electrode base plate 240S before the positive electrode plate 240 is formed, Figure 11 is a cross-sectional view of the positive electrode base plate 240S shown in Figure 10 from line XI, and Figure 12 is a front view showing the positive electrode plate 240 formed from the positive electrode base plate 240S.

[0066] The positive electrode plate 240, which is the second electrode, has a different polarity from 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 Figures 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 aluminum foil or aluminum alloy foil.

[0067] A positive electrode active material layer 242 is formed on the positive electrode core 241, except for one end on both sides. The positive electrode active material layer 242 is formed on the positive electrode core 241 by applying a positive electrode active material slurry using a die coater.

[0068] 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, carbon material as a conductive material, and N-methyl-2-pyrrolidone (NMP) as a dispersion medium, such that the mass ratio of lithium nickel cobalt manganese composite oxide:PVdF:carbon material is approximately 97.5:1:1.5.

[0069] 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 with a die coater. The positive electrode protective layer 243 has an electrical resistance greater than that of the positive electrode active material layer 242.

[0070] The positive electrode protective layer slurry is prepared by kneading alumina powder, carbon material as a conductive material, PVdF as a binder, and NMP as a dispersion medium, such that the mass ratio of alumina powder:carbon material:PVdF is approximately 83:3:14.

[0071] The positive electrode core 241, to which the positive electrode active material layer slurry and positive electrode protective layer slurry have been applied, is dried to remove NMP contained in the positive electrode active material layer slurry and positive electrode protective layer slurry, thereby forming the positive electrode active material layer 242 and positive electrode protective layer 243. Furthermore, by compressing the positive electrode active material layer 242, a positive electrode base plate 240S containing the positive electrode core 241, positive electrode active material layer 242, and positive electrode protective layer 243 is formed. The positive electrode plate 240 is formed by cutting the positive electrode base plate 240S into a predetermined shape. The positive electrode base plate 240S can be cut by laser processing using energy beam irradiation, mold processing, or cutter processing.

[0072] As shown in Figure 12, a plurality of positive electrode tabs 260 (first electrode tabs) made of a positive electrode core 241 are provided at one end in the width direction of the positive electrode plate 240 formed from a positive electrode base 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 protruding length of each of the plurality of positive electrode tabs 260 are appropriately adjusted considering the state in which the positive electrode tab group 250 is connected to the positive electrode current collector 400B. Note that the shape of the positive electrode tabs 260 is not limited to that shown in Figure 12.

[0073] A positive electrode protective layer 243 is provided at the base of each of the multiple positive electrode tabs 260. However, a positive electrode protective layer 243 is not necessarily provided at the base of each positive electrode tab 260.

[0074] In a typical example, the thickness of one negative electrode tab 230 is less than the thickness of one positive electrode tab 260. In this case, the thickness of the negative electrode tab group 220 is less than the thickness of the positive electrode tab group 250.

[0075] (Connection structure between electrode body 200 and current collector 400) Figure 13 is a cross-sectional view of the secondary battery shown in Figure 1 along line XIII-XIII. As shown in Figure 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). The electrode body 200 may be composed of three or more electrode bodies.

[0076] 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.

[0077] The first electrode body 201 includes a negative electrode tab group 220. The negative electrode tab group 220 is electrically connected to the 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 the current collector 430 (negative electrode current collector) at a third end 207 in the X direction.

[0078] The negative electrode tab group 220 has a curved portion 221 and a tip portion 222. The curved portion 221 is the part of the negative electrode tab group 220 that is curved on the side to which the first electrode is connected relative to the tip portion 222. The tip portion 222 is the part of the negative electrode tab group 220 that is located at the end opposite to the side to which the first electrode is connected.

[0079] The negative electrode tab group 270 has a curved portion 271 and a tip portion 272. The curved portion 271 is the part of the negative electrode tab group 270 that is curved on the side to which the first electrode is connected relative to the tip portion 272. The tip portion 272 is the part of the negative electrode tab group 270 that is located at the end opposite to the side to which the first electrode is connected.

[0080] Each of the negative electrode tab group 220 and negative electrode tab group 270 is curved in opposite directions such that their tips 222 and 272 are closer together. In this embodiment, the tips 222 and 272 are spaced apart, but the configuration is not limited to this, and the tips 222 and 272 may be in contact with each other.

[0081] 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. In this embodiment, the negative electrode current collector 400A is connected to the negative electrode terminal 301 between the electrode body 200 and the sealing plate 120.

[0082] The negative electrode current collector 400A includes current collectors 410 and 430 (third current collector), and current collector 440 (fourth current collector).

[0083] The current collector 410 is a plate-shaped member. The current collector 410 has a longitudinal direction in the Z direction and a short direction in the Y direction. The current collector 430 is a plate-shaped member. The current collector 430 has a longitudinal direction in the Z direction and a short direction in the Y direction. The current collectors 410 and 430 are arranged in parallel in the X direction. Thus, the current collectors 410 and 430 are composed of separate parts.

[0084] The negative electrode tab group 220 is joined to the current collector 410 at a joining point 411, which will be described later. The negative electrode tab group 270 is joined to the current collector 430 at a joining point 431, which will be described later. The joining points 411 and 431 can be formed by, for example, ultrasonic welding, resistance welding, laser welding, crimping, etc. In this 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.

[0085] The current collector 440 is joined to the current collectors 410 and 430 at a joint (not shown) located at its Z-direction end. The current collector 440 is connected to the negative terminal 301. The connection between the current collector 440 and the negative terminal 301 can be formed, for example, by crimping and / or welding.

[0086] The negative electrode terminal 301 is exposed on the outside of the sealing plate 120 and is positioned to reach the current collector 440 of the negative electrode current collector 400A, which is located on the inner surface side of the sealing plate 120. The negative electrode terminal 301 is connected to the plate-shaped member 303.

[0087] The plate-shaped member 303 is located on the outside of the sealing plate 120. The plate-shaped member 303 is arranged along the sealing plate 120. The plate-shaped member 303 is electrically conductive. The plate-shaped member 303 is positioned to secure connection area with busbars, etc., that electrically connect 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, for example, by laser welding.

[0088] An insulating member 510 is placed between the plate-shaped member 303 and the sealing plate 120. An insulating member 520 is placed between the negative terminal 301 and the sealing plate 120. An insulating member 530 is placed between the current collector 440 and the sealing plate 120.

[0089] However, the negative terminal 301 may be electrically connected to the sealing plate 120. Alternatively, the sealing plate 120 may serve the role of the negative terminal 301.

[0090] A spacer 600 is positioned 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 engaging portions (not shown) at both ends in the Z direction.

[0091] The first component 610 and the second component 620 protrude in the Y direction at their ends on the electrode body 200 side in the X direction. As a result, the spacer 600 acts as a guide to facilitate the bending of the curved portions 221 and 271 when they are bent.

[0092] A resin insulating sheet 700 (electrode holder) is placed between the electrode body 200 and the case body 110. The insulating sheet 700 may be made of resin, for example. More specifically, the material of the insulating sheet 700 may be polypropylene (PP), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyimide (PI), or polyolefin (PO).

[0093] Figure 14 is a cross-sectional view of the secondary battery shown in Figure 1, taken along line XIV-XIV. In this embodiment, the connection structure between the electrode body 200 and the current collector 400 on the positive electrode side of the secondary battery 1 differs from the negative electrode side in that the parts corresponding to the current collectors 410 and 430 on the negative electrode side are made of a single component.

[0094] The first electrode body 201 includes a group of positive electrode tabs 250. The group of positive electrode tabs 250 is electrically connected to the current collector 420 (positive electrode current collector) at a second end 206 in the X direction. The second electrode body 202 includes a group of positive electrode tabs 280. The group of positive electrode tabs 280 is electrically connected to the current collector 420 (positive electrode current collector) at a fourth end 208 in the X direction.

[0095] The positive electrode tab group 250 has a curved portion 251 and a tip portion 252. The curved portion 251 is the part of the positive electrode tab group 250 that is curved on the side to which the second electrode is connected relative to the tip portion 252. The tip portion 252 is the end of the positive electrode tab group 250 that is located on the side opposite to which the second electrode is connected.

[0096] The positive electrode tab group 280 has a curved portion 281 and a tip portion 282. The curved portion 281 is the part of the positive electrode tab group 280 that is curved on the side to which the second electrode is connected relative to the tip portion 282. The tip portion 282 is the part of the positive electrode tab group 280 that is located at the end opposite to the side to which the second electrode is connected.

[0097] Each of the positive electrode tab group 250 and the positive electrode tab group 280 is curved in opposite directions such that their tips 252 and 282 are closer together. In this embodiment, the tips 252 and 272 are spaced apart, but the configuration is not limited to this, and the tips 252 and 282 may be in contact with each other.

[0098] The positive electrode current collector 400B electrically connects the positive electrode terminal 302 to the positive electrode tab group 250 and the positive electrode tab group 280. In this embodiment, the positive electrode current collector 400B is connected to the positive electrode terminal 302 between the electrode body 200 and the sealing plate 130.

[0099] The positive electrode current collector 400B includes a current collector 420 (first current collector) and a current collector 450 (second current collector).

[0100] The current collector 420 is a plate-shaped member. The current collector 420 has a longitudinal direction in the Z direction and a short direction in the Y direction. The current collector 420 is composed of a single, integrated part.

[0101] The positive electrode tab group 250 and the positive electrode tab group 280 are joined to a current collector 420, which is made up of a single component, at a joint 421 described later. The joint 421 can be formed by, for example, ultrasonic welding, resistance welding, laser welding, crimping, etc. In this embodiment, the positive electrode tab group 250 and the positive electrode tab group 280 and the current collector 420 are joined by, for example, ultrasonic welding.

[0102] The current collector 450 is joined to the current collector 420 at a joint (not shown) located at its Z-direction end. The current collector 450 is connected to the positive terminal 302. The connection between the current collector 450 and the positive terminal 302 can be formed, for example, by crimping and / or welding.

[0103] The positive terminal 302 is exposed on the outside of the sealing plate 130 and is positioned to reach the current collector 450 of the positive current collector 400B, which is located on the inner side of the sealing plate 130. The positive terminal 302 is connected to the plate-shaped member 304.

[0104] The plate-shaped member 304 is located on the outside of the sealing plate 130. The plate-shaped member 304 is arranged along the sealing plate 130. The plate-shaped member 304 is conductive. The plate-shaped member 304 is arranged to secure connection area with busbars, etc., that electrically connect 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, for example, by laser welding.

[0105] An insulating member 510 is placed between the plate-shaped member 304 and the sealing plate 130. An insulating member 520 is placed between the positive terminal 302 and the sealing plate 130. An insulating member 530 is placed between the current collector 450 and the sealing plate 130.

[0106] However, the positive terminal 302 may be electrically connected to the sealing plate 130. Alternatively, the sealing plate 130 may also function as the positive terminal 302.

[0107] A spacer 600 is positioned between the sealing plate 130 and the main body of the electrode body 200 (excluding the positive electrode tab groups 250 and 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 engaging portions (not shown) at both ends in the Z direction.

[0108] The first component 610 and the second component 620 protrude in the Y direction at their ends on the electrode body 200 side in the X direction. As a result, the spacer 600 acts as a guide to facilitate the bending of the curved portions 251 and 281 when they are bent.

[0109] A resin insulating sheet 700 (electrode holder) is placed between the electrode body 200 and the case body 110.

[0110] (Manufacturing process for secondary battery 1) The method for manufacturing a secondary battery according to this embodiment will now be described. Figure 15 is a flowchart showing the method for manufacturing a secondary battery according to Embodiment 1. Figure 16 is a perspective view showing the state before the two electrode bodies of the secondary battery according to Embodiment 1 overlap. Figure 17 is a cross-sectional view taken along line XVII-XVII of the electrode body and current collector shown in Figure 16.

[0111] As shown in Figure 15, in the method for manufacturing a secondary battery according to this embodiment, first, the first electrode body 201 and the second electrode body 202 are manufactured (step S1). A portion of the tip of each of the negative electrode tab group 220, positive electrode tab group 250, negative electrode tab group 270, and positive electrode tab group 280 is cut so that when the tips are bundled together they are the same length.

[0112] As shown in Figures 15 to 17, after the first electrode body 201 and the second electrode body 202 are manufactured, 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 the joining point 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 the joining point 431.

[0113] Next, the first electrode body 201, the current collector 420, and the second electrode body 202 are arranged in this order in the first direction (DR1 direction). The positive electrode tab group 250 is placed on one side of the current collector 420 in the first direction (DR1 direction). With the positive electrode tab group 280 placed on the other side of the current collector 420 in the first direction (DR1 direction), the positive electrode tab group 250 and the positive electrode tab group 280 are joined to the current collector 420 (step S4). The positive electrode tab group 250 and the positive electrode tab group 280 are joined to the current collector 420 at the joining point 421.

[0114] In the height direction of the first electrode body 201 and the second electrode body 202, the current collectors 410, 420, and 430 are positioned off-center to one side of the center of the first electrode body 201 and the second electrode body 202. This allows the current collectors to be made shorter, thus enabling them to be made smaller.

[0115] Note that the current collectors 410, 420, and 430 are not limited to this configuration. The current collectors 410, 420, and 430 may be positioned in the center of the first electrode body 201 and the second electrode body 202 in the height direction. In this case, in the height direction of the first electrode body 201 and the second electrode body 202, 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 positioned in the center of the first electrode body 201 and the second electrode body 202 in accordance with the current collectors 410, 420, and 430.

[0116] Furthermore, the order in which the current collectors 410, 420, and 430 are joined 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 step of joining the current collectors 410 and 430 to the first electrode body 201 and the second electrode body 202 is preferably performed before the step of overlapping the first electrode body 201 and the second electrode body 202, which will be described later, and is preferably performed before the step of joining the current collector 420 to the first electrode body 201 and the second electrode body 202.

[0117] 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 bent in the thickness direction of the first electrode body 201 and the second electrode body 202 (in a direction perpendicular to the DR1 direction in Figures 16 and 17) to overlap the first electrode body 201 and the second electrode body 202 (step S5). In other words, the first electrode body 201 and the second electrode body 202 are brought together.

[0118] "Overlapping the first electrode and the second electrode" means that the first electrode and the second electrode may be directly overlapped, or other components may be placed between the first electrode and the second electrode. Furthermore, the first electrode and the second electrode may or may not be fixed with tape or the like. In addition, the first electrode, the current collector and the second electrode do not have to be arranged in a straight line in the first direction (DR1 direction), and the first electrode or the second electrode may be inclined with respect to the current collector in the first direction (DR1 direction).

[0119] The positive electrode tab group 250 and the positive electrode tab group 280 are bent so that their tips face each other. Similarly, the negative electrode tab group 220 and the negative electrode tab group 270 are also bent so that their tips face each other.

[0120] Figures 15 and 18 are perspective views showing the electrode body with the holder and spacer attached. As shown in Figure 18, the spacer 600 and insulating sheet 700 are then assembled onto the electrode body 200 (step S6).

[0121] The insulating sheet 700 does not necessarily need to cover the entire surface of the electrode body 200. Preferably, the insulating sheet 700 covers an area of ​​50% or more, more preferably 70% or more, of the outer surface of the electrode body. Preferably, the insulating sheet 700 covers the entirety of four of the six surfaces of the substantially rectangular parallelepiped (flat-shaped) electrode body 200, excluding the two surfaces on which the negative electrode tab group 220 and the positive electrode tab group 250 are formed, respectively.

[0122] Figure 19 is a perspective view showing the negative electrode current collector with the sealing plate 120 attached. Figure 20 is a cross-sectional view of the electrode and current collector shown in Figure 19, taken along line XX-XX.

[0123] As shown in Figures 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 superimposed. 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.

[0124] Specifically, the negative electrode tab group 220 and the negative electrode tab group 270 are bent so that their tips 222 and 272 face each other.

[0125] 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. Note that the connection of the plate-shaped member 303 to the negative electrode terminal 301 can be done at any time. The current collector 440 and the current collectors 410 and 430 are joined by laser welding from between the sealing plate 120 and the insulating sheet 700.

[0126] Figure 21 is a perspective view showing the electrode body inserted into the case body. As shown in Figures 15 and 21, the first electrode body 201 and the second electrode body 202 are then superimposed, and the first electrode body 201 and the second electrode body 202 are inserted into the case body 110 through the opening 113, with the current collector 420 side leading (step S8).

[0127] 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 (first electrode body 201 and second electrode body 202) closer together. It is preferable to bring the sealing plate 120 and the case body 110 closer together by bringing the sealing plate 120 and the main body of the electrode body 200, which is placed inside the case body 110, closer together. As shown in Figure 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 portions of the curved parts 221 and 271 are closer to the case body 110 in the Y direction.

[0128] 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. This temporary joining partially joins the sealing plate 120 to the opening 113 of the case body 110. This positions the sealing plate 120 relative to the case body 110.

[0129] 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 pushed from the current collector 410 and current collector 430 side. When the electrode body 200 is pushed from the current collector 410 and current collector 430 side, the negative electrode tab group 220 and the negative electrode tab group 270 can be bent at the same time.

[0130] Figure 22 is a perspective view showing the positive electrode current collector with the sealing plate 130 attached. Figure 23 is a cross-sectional view of the electrode body and current collector shown in Figure 22 along line XXIII-XXIII. Figure 24 is a view of the current collector shown in Figure 22 from the direction of arrow XXIV. Figure 25 is a cross-sectional view of the current collector shown in Figure 24 along line XXV-XXV. Note that the case body 110 is omitted in Figure 23.

[0131] As shown in Figures 15 and 22-25, after inserting the first electrode body 201 and the second electrode body 202 into the case body 110, the current collector 420 is electrically connected to the positive terminal 302 (step S9).

[0132] Specifically, the positive electrode terminal 302 and the current collector 450 are attached to the sealing plate 130 via an insulating member. After inserting the first electrode body 201 and the second electrode body 202 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-shaped member 304 to the positive electrode terminal 302 can be done at any time.

[0133] As shown in Figure 25, the current collector 420 (first current collector 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 bent portion) located between the first region 10 and the second region 20. The current collector 450 (second current collector 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 bent 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.

[0134] In the example shown in Figure 25, the current collectors 420 and 450 are bent at approximately right angles in the intermediate sections 15 and 35, respectively. However, the bending angle of the current collectors 420 and 450 is not limited to 90°. Preferably, a bending angle of about 45° to 135° can be used. Notches may be provided at both ends of the bent portion of the current collectors 420 and 450 in the width direction (Y direction) to facilitate the bending process. The bent portion may include a rounded (R) portion.

[0135] The first region 10 of the current collector 420 and the third region 30 of the current collector 450 are arranged in overlapping positions. The first region 10 is located closer to the electrode body 200 than the third region 30. The positive electrode tab groups 250 and 280 are connected to the first region 10 of the current collector 420.

[0136] The first region 10 and the third region 30 only need to overlap when viewed from the X direction and do not necessarily need to be in contact. However, it is preferable that the first region 10 and the third region 30 are located relatively close to each other, 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.

[0137] When viewed from the X direction perpendicular to the sealing plate 130, the overlapping area of ​​the first region 10 and the third region 30 is 100 mm². 2 It is preferable that the above conditions are met. When viewed from the X direction, the area of ​​the third region 30 may be larger than the area of ​​the first region 10. Here, the overlapping area of ​​the first region 10 and the third region 30 is preferably 50% or more of the area of ​​the third region 30, and more preferably 70% or more. In addition, 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 made of, for example, an insulating tape or a resin plate.

[0138] The current collector 420 or current collector 450 may have a fuse section formed in it, consisting of a through hole, a thin-walled section (groove), or a notch. This allows the fuse section to melt and interrupt the current when an external short circuit occurs. The fuse section may be provided in any of the first region 10, the second region 20, the third region 30, or the fourth region 40.

[0139] The second region 20 of the current collector 420 and the fourth region 40 of the current collector 450 are arranged in an overlapping manner. This creates a contact region R11 where the current collector 420 and the current collector 450 overlap each other.

[0140] When connecting the current collector 420 to the current collector 450, a high-energy ray 2 is irradiated from between the sealing plate 130 and the end of the case body 110 on the opening 114 side to at least one of the current collectors 420 and 450 located in the contact region R11. Additionally, a high-energy ray 2 is irradiated from between the sealing plate 130 and the end of the case body 110 on the opening 114 side to at least one of the current collectors 440 and 450. The high-energy ray 2 is, for example, laser light. As a result, the current collectors 420 and 450 are welded together at the welding position P1 in the contact region R11.

[0141] In one example, when the current collector 420 and the current collector 450 are joined, the end of the positive electrode active material layer 242 (first electrode active material layer) on the opening 114 side is located inside the case body 110.

[0142] The welding method between the current collector 420 and the current collector 450 is, for example, through welding. The current collector 450 may have a thin-walled section, and the current collectors may be welded together at the thin-walled section, or the current collector 450 may have a through hole, and the current collectors may be welded together at a position away from the through hole.

[0143] Figure 26 is a cross-sectional view of the current collector on the sealing plate 120 side (negative electrode side), corresponding to Figure 25. As shown in Figure 26, the connections between current collectors on the sealing plate 120 side (negative electrode side) can be configured in the same way as the connections between current collectors on the sealing plate 130 side (positive electrode side).

[0144] Specifically, the separate current collectors 410 and 430 (multiple third current collectors) each have a fifth region 50 extending along the sealing plate 130, a sixth region 60 extending in a direction perpendicular to the sealing plate 130, and an intermediate portion 55 (third bent portion) located between the fifth region 50 and the sixth region 60. The single current collector 440 (fourth current collector) has a seventh region 70 extending along the sealing plate 130, an eighth region 80 extending in a direction perpendicular to the sealing plate 130, and an intermediate portion 75 (fourth bent portion) located between the seventh region 70 and the eighth region 80. The sixth region 60 and the eighth region 80 extend from the ends of the fifth region 50 and the seventh region 70 toward the electrode body 200.

[0145] The fifth region 50 of the current collectors 410 (first third current collector) and 430 (second third current collector) and the seventh region 70 of the current collector 440 are arranged on top of each other. The fifth region 50 is located closer to the electrode body 200 than the seventh region 70. The negative electrode tab group 220 (first tab or first tab group) and the negative electrode tab group 270 (second tab or second tab group) are connected to the fifth region 50 of the current collectors 410 and 430, respectively.

[0146] In addition, the same configuration as that of the sealing plate 130 side (positive electrode side) can be adopted on the sealing plate 120 side (negative electrode side). Furthermore, the current collector 420 on the sealing plate 130 side (positive electrode side) may be divided into multiple (two) components, similar to the current collectors 410 and 430 on the sealing plate 120 side (negative electrode side).

[0147] In this embodiment, the contact region R11 is formed to extend in the XY plane direction. Therefore, the high-energy rays 2 for joining the current collector 420 and the current collector 450 can be irradiated from a direction parallel to the Z direction. As a result, the high-energy rays 2 can be configured to be less likely to interfere with the case body 110 or the sealing plate 130.

[0148] Furthermore, the connections between current collectors on the sealing plate 120 side (negative electrode side) can be configured in the same way as the connections between current collectors on the sealing plate 130 side (positive electrode side). Also, the current collector 420 on the sealing plate 130 side (positive electrode side) may be divided into multiple (two) components, similar to the current collectors 410 and 430 on the sealing plate 120 side (negative electrode side).

[0149] As shown in Figure 23, the positive electrode tab groups 250 and 280 connected to the current collector 420 are bent so that their tips 252 and 282 face each other. From the state shown in Figures 23 to 25, the sealing plate 130 is brought into contact with the case body 110. At this time, the positive electrode tab groups 250 and 280 are curved by bringing the sealing plate 130 and the main body of the electrode body 200 closer together. As shown in Figure 14, the positive electrode tab groups 250 and 280 are curved along the shape of the spacer 600 so that the folded portions of the curved parts 251 and 281 are closer to the case body 110 in the Y direction.

[0150] After the sealing plate 130 is brought into contact with the case body 110, the sealing plate 130 is tack-welded to the case body 110. Through this tack-welding, the sealing plate 130 is partially joined to the opening 114 of the case body 110. This positions the sealing plate 130 relative to the case body 110.

[0151] Figure 27 is a perspective view showing the configuration of a secondary battery according to Embodiment 1. As shown in Figures 15 and 27, the sealing plates 120 and 130 are then joined to the case body 110 (step S10). The sealing plate 120 seals the opening 113 of the case body 110, and the sealing plate 130 seals the opening 114 of the case body 110. As a result, the first electrode body 201 and the second electrode body 202 are housed in the case 100.

[0152] After the above-described process, inspections such as leak testing are performed (S11 step). After the leak testing, 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 injection hole 134. When injecting the electrolyte, the case 100 is tilted with the sealing plate 130 facing upwards and the sealing plate 120 facing downwards, and the electrolyte is injected into the inside of the case 100 through the injection hole 134 of the sealing plate 130. After that, degassing and charging are performed. During degassing and charging, the injection hole 134 may be temporarily sealed. After that, the injection hole 134 is sealed, and the secondary battery 1 is completed.

[0153] The order of the electrode body 200 insertion step and the current collector connection step is not limited to the example described above. For example, after inserting only a portion of the electrode body 200 into the case body 110 (first step) such that the end of the negative electrode active material layer 212 (second electrode active material layer) on the opening 113 side is located outside the case body 110, the negative electrode terminal 301 (second electrode terminal) provided on the sealing plate 120 (second sealing plate) is electrically connected to the negative electrode tab group 220, 270 (second electrode tab), and then the electrode body 200 is inserted into the case body 110 until the end of the negative electrode active material layer 212 on the opening 113 side is located inside the case body 110 (second step). In other words, the negative electrode terminal 301 and the electrode body 200 can be electrically connected during the insertion step of the electrode body 200 into the case body 110.

[0154] In this embodiment, by providing a negative electrode tab group 220 and a positive electrode tab group 250 on the first electrode body 201, and a negative electrode tab group 270 and a positive electrode tab group 280 on the second electrode body 202, 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 shortened compared to the case where the first electrode body 201 and the second electrode body 202 form a single electrode tab and this electrode tab is folded. As a result, the occupied volume of 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 the electrode tabs easier to bend compared to the case where the first electrode body 201 and the second electrode body 202 form a single electrode tab, making it easier to connect the electrode tabs to the current collector and enabling the stable manufacture of the secondary battery. In particular, the ability to stably manufacture the secondary battery 1 increases the reliability of the connection between the electrode tabs and the current collector.

[0155] In this embodiment, by providing a contact region R11, a region where current collectors can be joined together can be secured, enabling stable connection of the current collectors. When connecting current collectors by irradiating them with high-energy rays 2 from between the opening 114 of the case body 110 and the sealing plate 130, it is possible to easily secure a weldable range between the current collectors when irradiated with high-energy rays 2 from a second direction (Z direction) that intersects the first direction in which the openings 113 and 114 are aligned.

[0156] Furthermore, by irradiating at least one of the current collectors 420 and 450 with high-energy rays 2 from between the sealing plate 130 and the end of the case body 110 on the opening 114 side, and welding the current collectors 420 and 450 together, the current collectors on the opening 114 side can be stably connected to each other after the electrode body 200 has been inserted into the case body 110.

[0157] In this embodiment, a spacer 600 (resin member) is placed between the welding position P1, where the high-energy rays 2 are irradiated, and the main body of the electrode body 200, in the X direction perpendicular to the sealing plate 130. This suppresses the reflection of laser light or metal sputter from hitting the electrode body 200 when the current collector 420 and the current collector 450 are joined, thereby effectively protecting the electrode body 200.

[0158] The secondary batteries according to Embodiment 2 and Embodiment 3 will be described below. Regarding the secondary batteries according to Embodiment 2 and Embodiment 3, configurations that are the same as those of secondary battery 1 according to Embodiment 1, and configurations that are the same between Embodiment 2 and Embodiment 3, will not be repeated in the description.

[0159] (Embodiment 2) Figure 28 is a cross-sectional view showing the configuration of a secondary battery according to Embodiment 2. As shown in Figure 28, in the secondary battery according to Embodiment 2, the tips 222A and 272A of each of the negative electrode tab group 220A and negative electrode tab group 270A are bent in the same direction in the Y direction.

[0160] Subsequently, the first electrode body 201A and the second electrode body 202A are inserted into the case body, and the sealing plate 120 is brought into contact with the case body. As a result, the negative electrode tab group 220A and the negative electrode tab group 270A each curve in the same direction so that their tips 222A and 272A face the same direction. To facilitate the curving of the tips 222A and 272A in the same direction, a 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 ensuring that the tips 222A and 272A of the negative electrode tab group 220A and the negative electrode tab group 270A are curved in the same direction in the Y direction, 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 can be prepared with the same configuration. As a result, 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 can be configured as one type, thereby simplifying the manufacturing process.

[0162] (Embodiment 3) Figure 29 is a perspective view showing the configuration of the current collector of the secondary battery according to Embodiment 3. Figure 30 is a cross-sectional view of the current collector shown in Figure 29 along the line XXX-XXX.

[0163] As shown in Figure 30, the current collector 420B (first current collector) has a first region 10B extending along the sealing plate 130, a second region 20B extending in a direction intersecting the sealing plate 130, and an intermediate portion 15B (first bent portion) located between the first region 10B and the second region 20B. The current collector 450B (second current collector) has a third region 30B extending along the sealing plate 130, a fourth region 40B extending in a direction intersecting the sealing plate 130, and an intermediate portion 35B (second bent portion) located between the third region 30B and the fourth region 40B.

[0164] The first region 10B of current collector 420B and the third region 30B of current collector 450B are arranged in overlapping positions. The first region 10B is located closer to the electrode body 200 than the third region 30B. Positive electrode tab groups 250 and 280 are connected to the first region 10B of current collector 420B.

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

[0166] The second region 20B constitutes a first protruding region that protrudes toward the electrode body 200 more than the first region 10B, and the fourth region 40B constitutes a second protruding region that protrudes toward the electrode body 200 more than the third region 30B. The second region 20B and the fourth region 40B are arranged on top of each other. This forms 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) that is 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, it is preferable that there is a gap G1 between the current collector 420B and the current collector 450B. This makes it easier to preferentially bring the current collectors into contact with each other in the contact region R31. In addition, the reaction force caused by the bending of the electrode tab acts on the current collector 420B, which allows the current collector 420B and the current collector 450B to be in close contact. The size of the gap G1 (in the X direction) is preferably about 2.0 mm or less, and more preferably about 1.0 mm or less.

[0169] Figure 31 is a cross-sectional view of the current collector on the sealing plate 120 side (negative electrode side) corresponding to Figure 30. As shown in Figure 31, the current collectors 410B and 430B (multiple third current collector members) provided on the sealing plate 120 side (negative electrode side) and separated from each other each have a fifth region 50B extending along the sealing plate 120, a sixth region 60B extending in a direction intersecting the sealing plate 130, and an intermediate portion 55B (third bent portion) located between the fifth region 50B and the sixth region 60B. The single current collector 440B (fourth current collector member) has a seventh region 70B extending along the sealing plate 130, an eighth region 80B extending in a direction intersecting the sealing plate 130, and an intermediate portion 75B (fourth bent portion) located between the seventh region 70B and the eighth region 80B.

[0170] The fifth region 50B of the current collectors 410B (the first third current collector) and 430B (the second third current collector) and the seventh region 70B of the current collector 440B are arranged in overlapping positions. The fifth region 50B is located closer to the electrode body 200 than the seventh region 70B. The negative electrode tab group 220 (first tab or first tab group) and the negative electrode tab group 270 (second tab or second tab group) are connected to the fifth region 50B of the current collectors 410B and 430B, respectively.

[0171] The sixth region 60B of the current collector 420B and the eighth region 80B of the current collector 450B have a roughly L-shape. The sixth region 60B and the eighth region 80B are folded back from the YZ plane to have a convex shape toward the case body 110.

[0172] The sixth region 60B constitutes a third protruding region that protrudes further toward the electrode body 200 than the fifth region 50B, and the eighth region 80B constitutes a fourth protruding region that protrudes further toward the electrode body 200 than the seventh region 70B. The sixth region 60B and the eighth region 80B are arranged on top of each other. This forms a contact region R31 where the current collector 420B and the current collector 450B overlap each other.

[0173] In this embodiment, by providing a contact region R31, a region where current collectors can be joined together can be secured, enabling stable connection of the current collectors. When connecting current collectors by irradiating them with high-energy rays 2 from between the opening 114 of the case body 110 and the sealing plate 130, it is possible to easily secure a weldable range between the current collectors when irradiated with high-energy rays 2 from a direction intersecting the first direction in which the openings 113 and 114 are aligned.

[0174] Preferably, the sealing plates 120 and 130 each have a pair of long edges arranged parallel to each other and a short edge that is shorter than the pair of long edges arranged parallel to each other. Here, the direction in which the long edges extend is the longitudinal direction.

[0175] In the embodiments 1 to 3 described above, an example was described in which, in the step of connecting the current collectors by irradiating them with high-energy rays 2, the sealing plate 130 is arranged substantially parallel to the YZ plane and overlaps with approximately 100% of the area of ​​the opening 114 when projected onto the opening 114 along the X direction. However, this technology is not limited to this. For example, in the above step, the sealing plate 130 may be inclined with respect to the YZ plane, for example, by about 30° or less (more preferably about 15° or less, and even more preferably about 10° or less). It is also preferable that when the sealing plate 130 is projected onto the opening 114 along the X direction, it overlaps with about 60% or more of the area of ​​the opening 114 (preferably about 80% or more, more preferably about 90% or more). Note that the step of connecting the current collectors by irradiating them with high-energy rays 2 can also be performed before inserting the electrode body 200 into the case body 110.

[0176] While embodiments of the present technology have been described above, the embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of the present technology is defined by the claims, and all modifications within the meaning and scope equivalent to the claims are intended to be included. [Explanation of symbols]

[0177] 1 Secondary battery, 2 High-energy rays, 10,10B First region, 15,15B,35,35B Intermediate region, 20,20B Second region, 30,30B Third region, 40,40B Fourth region, 50,50B Fifth region, 55,55B,75,75B Intermediate region, 60,60B Sixth region, 70,70B Seventh region, 80,80B Eighth region, 100 Case, 110 Case body, 111 First side section, 112,112A,112B Second side section, 113,114 Opening, 115 Joint, 120,130 Sealing plate, 134 Injection hole, 150 Gas discharge valve, 200,200A Electrode body, 201,201A First electrode body, 202,202A 205 Second electrode body, 1st 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 section, 222, 222A, 272, 272A Tip section, 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 section, 252, 282 Tip section, 260 Positive electrode tab, 300 Electrode terminal, 301 Negative electrode terminal, 302 Positive terminal, 303, 304; Plate-shaped member, 400, 410, 410B, 420, 420B, 430, 430B, 440, 450, 450B; Current collector, 400A; Negative current collector, 400B; Positive current collector, 411, 421, 431; Joint point, 510, 520, 530; Insulating member, 600, 600A; Spacer, 610; First component, 620; Second component, 630A; Third component, 700; Insulating sheet.

Claims

1. An electrode body including a first electrode, a second electrode having a different polarity from the first electrode, and a first electrode tab electrically connected to the first electrode, A case comprising a case body having a first opening and a first wall consisting of a first sealing plate that seals the first opening, for housing the electrode body, A first current collector member directly and electrically connected to the first electrode tab, The system comprises a second current collector connected to the first current collector, The first current collector member has a first region extending along the first wall, a second region extending in a direction intersecting the first wall, and a first bent portion provided between the first region and the second region. The second current collector member has a third region extending along the first wall, a fourth region extending in a direction intersecting the first wall, and a second bent portion provided between the third region and the fourth region. The first region and the third region are arranged on top of each other, and the first region is located closer to the electrode body than the third region. The first electrode tab is connected to the first region, The second region and the fourth region are welded together. A secondary battery wherein the first current collector and the second current collector are made of aluminum or an aluminum alloy, or the first current collector and the second current collector are made of copper or a copper alloy.

2. The case includes a second wall opposite the first wall, A first electrode tab is provided at the end of the electrode body on the first wall side, and a group of electrode tabs electrically connected to the second electrode is provided at the end of the electrode body on the second wall side. The aforementioned secondary battery is Multiple third current collectors are electrically connected to the electrode tab group, A fourth current collector member connected to each of the plurality of third current collector members, The fourth current collector is electrically connected to a second electrode terminal provided on the second wall, The secondary battery according to claim 1, wherein the electrode tab group includes a first tab connected to one of the plurality of third current collectors and a second tab connected to another of the plurality of third current collectors.

3. Each of the aforementioned plurality of third current collector members has a fifth region extending along the second wall, a sixth region extending in a direction intersecting the second wall, and a third bent portion provided between the fifth region and the sixth region. The fourth current collector member has a seventh region extending along the second wall, an eighth region extending in a direction intersecting the second wall, and a fourth bent portion provided between the seventh region and the eighth region. The fifth region and the seventh region are arranged to overlap, and the fifth region is located closer to the electrode body than the seventh region. The electrode tab group is connected to the fifth region, The secondary battery according to claim 2, wherein the sixth region and the eighth region are joined together.

4. The fourth current collector member consists of a single member, The secondary battery according to claim 2 or claim 3, wherein each of the plurality of third current collectors is joined to a single fourth current collector.

5. The second current collector member consists of a single member, A secondary battery according to any one of claims 1 to 3, wherein the first current collector is joined to a single second current collector.

6. An electrode body including a first electrode, a second electrode having a different polarity from the first electrode, and a first electrode tab electrically connected to the first electrode, A case comprising a case body having a first opening and a first wall consisting of a first sealing plate that seals the first opening, for housing the electrode body, A first current collector member directly and electrically connected to the first electrode tab, The system comprises a second current collector connected to the first current collector, The first current collector member has a first region extending along the first wall, a second region extending in a direction intersecting the first wall, and a first bent portion provided between the first region and the second region. The second current collector member has a third region extending along the first wall, a fourth region extending in a direction intersecting the first wall, and a second bent portion provided between the third region and the fourth region. The first region and the third region are arranged on top of each other, and the first region is located closer to the electrode body than the third region. The first electrode tab is connected to the first region, A secondary battery wherein the fourth region has a thin-walled portion that is relatively less thick than the surrounding area, and the second region and the fourth region are welded together in the thin-walled portion.

7. In a direction perpendicular to the first wall, A secondary battery according to any one of claims 1 to 3, wherein a resin member is disposed between the joint portion of the first current collector and the second current collector and the main body of the electrode body.

8. The second region extends from the end of the first region toward the electrode body, The secondary battery according to any one of claims 1 to 3, wherein the fourth region extends from the end of the third region toward the electrode body.

9. The second region has a first protruding region that protrudes toward the electrode body side more than the first region, The fourth region has a second protruding region that protrudes further toward the electrode body than the third region, The first protruding region and the second protruding region are arranged to overlap, The secondary battery according to any one of claims 1 to 3, wherein the first protruding region and the second protruding region are joined together.

10. An insulating member is placed between the first wall and the second current collector, The secondary battery according to claim 9, wherein the end of the second protruding region that is farther from the third region is in contact with the insulating member.

11. An electrode body including a first electrode, a second electrode having a different polarity from the first electrode, and a first electrode tab electrically connected to the first electrode, A case including a first wall and housing the electrode body, A first current collector member electrically connected to the first electrode tab, The system comprises a second current collector connected to the first current collector, The first current collector member has a first region extending along the first wall, a second region extending in a direction intersecting the first wall, and a first bent portion provided between the first region and the second region. The second current collector member has a third region extending along the first wall, a fourth region extending in a direction intersecting the first wall, and a second bent portion provided between the third region and the fourth region. The first region and the third region are arranged on top of each other, and the first region is located closer to the electrode body than the third region. The first electrode tab is connected to the first region, The second region and the fourth region are joined together. The first region is a secondary battery, which is located on the third region via an insulating member.

12. A secondary battery according to any one of claims 1 to 3, wherein a fuse portion is provided in at least one of the first current collector and the second current collector.

13. The aforementioned case includes a second sealing plate, The case body has a second opening located opposite the first opening, The first opening is sealed by the first sealing plate. The second opening is sealed by the second sealing plate. The first sealing plate is provided with a first electrode terminal electrically connected to the first electrode. The second sealing plate is provided with a second electrode terminal that is electrically connected to the second electrode. The first wall is the first sealing plate, The electrode body has a group of first electrode tabs electrically connected to the first electrode at the end on the first sealing plate side, The secondary battery according to any one of claims 1 to 3, wherein the electrode body has a group of second electrode tabs electrically connected to the second electrode at the end on the second sealing plate side.

14. An electrode body including a first electrode, a second electrode having a different polarity from the first electrode, and a first electrode tab electrically connected to the first electrode, A case including a first wall and housing the electrode body, A first current collector member electrically connected to the first electrode tab, The system comprises a second current collector connected to the first current collector, The first current collector member has a first region extending along the first wall, a second region extending in a direction intersecting the first wall, and a first bent portion provided between the first region and the second region. The second current collector member has a third region extending along the first wall, a fourth region extending in a direction intersecting the first wall, and a second bent portion provided between the third region and the fourth region. The first region and the third region are arranged on top of each other, and the first region is located closer to the electrode body than the third region. The first electrode tab is connected to the first region, The second region and the fourth region are joined together. The first wall includes a through hole, A first electrode terminal is placed inside the through hole. The first electrode terminal is connected to the third region, and the battery is a secondary battery.

15. An electrode body including a first electrode, a second electrode having a different polarity from the first electrode, and a first electrode tab electrically connected to the first electrode, A case including a first wall and housing the electrode body, A first current collector member electrically connected to the first electrode tab, The system comprises a second current collector connected to the first current collector, The first current collector member has a first region extending along the first wall, a second region extending in a direction intersecting the first wall, and a first bent portion provided between the first region and the second region. The second current collector member has a third region extending along the first wall, a fourth region extending in a direction intersecting the first wall, and a second bent portion provided between the third region and the fourth region. The first region and the third region are arranged on top of each other, and the first region is located closer to the electrode body than the third region. The first electrode tab is connected to the first region, A method for manufacturing a secondary battery, wherein the second region and the fourth region are joined together, A first step is to connect the first electrode tab to the first region of the first current collector, which is not connected to the second current collector; A method for manufacturing a secondary battery, comprising: a second step after the first step, overlapping the second region and the fourth region and joining the second region and the fourth region by welding.

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