Secondary battery and manufacturing method thereof

Abstract

To provide a secondary battery having high energy density and excellent output and regeneration characteristics, and a method for manufacturing the same.SOLUTION: A first end surface and a second end surface of an electrode body have a shape in which a second direction approximately perpendicular to a first direction is a short direction, and a third direction approximately perpendicular to the first direction and the second direction is a long direction. A first electrode tab group includes a first group and a second group spaced apart from the first group. Each of the first and second groups has a base portion, a curved portion located closer to a tip than the base portion, and a joint located closer to the tip than the curved portion and joined to a first current collector. The base portions of the first and second groups are located on opposite sides to each other with respect to an axis in the second direction and are located on opposite sides to each other with respect to an axis in the third direction.SELECTED DRAWING: Figure 12

Description

[Technical Field]

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

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

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

[0004] From the viewpoint of improving the energy density of the secondary battery and improving the output and regeneration characteristics of the secondary battery, there is room for further improvement in the battery described in Patent Document 1.

[0005] The purpose of this technology is to provide a secondary battery with high energy density and excellent output and regeneration characteristics, as well as a manufacturing method for such a battery. [Means for solving the problem]

[0006] The present technology provides the following secondary battery and method for manufacturing the same.

[0007] [1] An electrode body having a first end face located at one end side in a first direction and a second end face located at the other end side in the first direction, the electrode body including a first electrode and a second electrode having a polarity different from that of the first electrode, the flat electrode body having a first electrode tab group electrically connected to the first electrode on the first end face side and a second electrode tab group electrically connected to the second electrode on the second end face side, a case that houses the electrode body, a first current collector electrically connected to the first electrode tab group, and a second current collector electrically connected to the second electrode tab group, the case comprising: a case main body having a first opening and a second opening opposite the first opening; a first sealing plate having a second electrode terminal and sealing the second opening, the first end face and the second end face having a shape in which a second direction substantially perpendicular to the first direction is its short side direction, and a third direction substantially perpendicular to the first and second directions is its long side direction, the first electrode tab group including a first group and a second group spaced apart from the first group, the first group and the second group each having a root portion, a curved portion located closer to the tip than the root portion, and a joint portion located closer to the tip than the curved portion and joined to the first current collector, the root portions of the first group and the second group being located on opposite sides to each other with respect to an axis in the second direction and also on opposite sides to each other with respect to an axis in the third direction.

[0008] [2] The secondary battery according to [1], wherein the second electrode tab group includes a third group and a fourth group spaced apart from the third group, and the third and fourth groups each have a root portion, a curved portion located closer to the tip than the root portion, and a joint portion located closer to the tip than the curved portion and joined to the second current collector, and the root portions of the third and fourth groups are located on opposite sides of each other with respect to the axis in the second direction and are also located on opposite sides of each other with respect to the axis in the third direction.

[0009] [3] The secondary battery according to [1] or [2], further comprising a gas release valve provided on the first sealing plate, wherein when viewed from the first direction, the gas release valve is located between the first group of joints and the second group of joints and has an area that does not overlap with the first current collector.

[0010] [4] The secondary battery according to [1] or [2], further comprising: a gas release valve provided in the first sealing plate; and an insulating member disposed between the first sealing plate and the electrode body so that at least a portion of the insulating member overlaps with the gas release valve, wherein when viewed from a first direction, the insulating member has a notch or a through-hole in the area overlapping with the gas release valve.

[0011] [5] A method for manufacturing a flat electrode body having a first end face located at one end in a first direction and a second end face located at the other end in the first direction, the flat electrode body including a first electrode and a second electrode having a polarity different from that of the first electrode, the flat electrode body having a first electrode tab group electrically connected to the first electrode at the first end face and a second electrode tab group electrically connected to the second electrode at the second end face, the method comprising: inserting the electrode body into the case body; after inserting the electrode body into the case body, electrically connecting a first electrode terminal provided on a first sealing plate to the first electrode tab group via a first current collector; and electrically connecting a second electrode terminal provided on a second sealing plate to the second electrode tab group via a second current collector. and electrically connecting a second electrode terminal to the second electrode tab group, and then sealing the first opening with a first sealing plate. The first end face and the second end face have a shape in which a second direction substantially perpendicular to the first direction is its short side direction, and a third direction substantially perpendicular to the first and second directions is its long side direction. The first electrode tab group includes a first group and a second group spaced apart from the first group, and each of the first and second groups has a root portion, a curved portion located closer to the tip than the root portion, and a joint portion located closer to the tip than the curved portion and joined to the first current collector. The root portions of the first group and the second group are located on opposite sides of each other with respect to an axis in the second direction and also on opposite sides of each other with respect to an axis in the third direction. [Effects of the Invention]

[0012] According to the secondary battery and manufacturing method thereof of the present technology, the first electrode tab group is formed into a first group and a second group, and each of the first electrode tab groups is joined to a first current collector. By forming the electrode tab group into multiple groups in this way, the output and regeneration characteristics of the secondary battery can be improved.

[0013] In addition, by arranging the root portions of the first and second groups of the first electrode tab group on opposite sides of two axes (the axis in the second direction and the axis in the third direction), and bending the first and second groups before joining them to the first current collector, space can be saved around the first current collector.

[0014] As described above, according to the present technology, it is possible to provide a secondary battery having high energy density and excellent output and regeneration characteristics, and a method for manufacturing the same. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 2 is a front view of the secondary battery. [Figure 2] 2 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow II. [Figure 3] 3 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow III. [Figure 4] 4 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow IV. FIG. [Figure 5] FIG. 2 is a front cross-sectional view of the secondary battery shown in FIG. [Figure 6] FIG. 2 is a front view showing a positive electrode plate before it is formed into a positive electrode plate. [Figure 7] 7 is a cross-sectional view taken along the line VII-VII of the positive electrode plate shown in FIG. 6. [Figure 8] FIG. 2 is a front view showing a positive electrode plate formed from a positive electrode original plate. [Figure 9] FIG. 2 is a front view showing a negative electrode blank before being formed into a negative electrode plate. [Figure 10] 10 is a cross-sectional view taken along the line XX in FIG. 9. [Figure 11] FIG. 2 is a front view showing a negative electrode plate formed from a negative electrode original plate. [Figure 12] FIG. 2 is a diagram showing a connection structure between a positive electrode tab group and a positive electrode current collector. [Figure 13] FIG. 1 is a diagram (part 1) showing an example of the arrangement of the base portion of a positive electrode tab group. [Figure 14] FIG. 2 is a diagram (part 2) showing an example of the arrangement of the base portion of the positive electrode tab group. [Figure 15] FIG. 10 is a diagram (part 3) showing an example of the arrangement of the base portion of the positive electrode tab group. [Figure 16] FIG. 4 is a diagram (part 4) showing an example of the arrangement of the base portion of the positive electrode tab group. [Figure 17] FIG. 1 is a diagram (part 1) showing an example of the shape of a positive electrode tab group. [Figure 18] FIG. 18 is a perspective view of the positive electrode tab shown in FIG. 17. [Figure 19] FIG. 2 is a diagram (part 2) showing an example of the shape of a positive electrode tab group. [Figure 20] FIG. 20 is a perspective view of the positive electrode tab shown in FIG. 19. [Figure 21] FIG. 2 is a flow chart showing each step of a method for manufacturing a secondary battery. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, embodiments of the present technology will be described. Note that the same or corresponding parts are denoted by the same reference characters, and description thereof may not be repeated.

[0017] In the embodiments described below, when numbers, amounts, etc. are mentioned, the scope of the present technology is not necessarily limited to those numbers, amounts, etc., unless otherwise specified. Furthermore, in the following embodiments, each component is not necessarily essential to the present technology, unless otherwise specified. Furthermore, the present technology is not necessarily limited to those that achieve all of the effects and advantages mentioned in the present embodiments.

[0018] In this specification, the terms "comprise," "include," and "have" are open-ended. That is, when a certain feature is included, other features may or may not be included.

[0019] Furthermore, when geometric terms and terms expressing positional and directional relationships are used in this specification, such as "parallel," "orthogonal," "45° diagonal," "coaxial," and "along," these terms allow for manufacturing errors and slight variations. When terms expressing relative positional relationships, such as "upper side" and "lower side," are used in this specification, these terms are used to indicate relative positional relationships in a single state, and the relative positional relationships can be reversed or rotated to any angle depending on the installation direction of each mechanism (for example, by turning the entire mechanism upside down).

[0020] In this specification, the term "battery" is not limited to lithium-ion batteries, but may include other batteries such as nickel-metal hydride batteries and sodium-ion batteries. In this specification, the term "electrode" may collectively refer to positive and negative electrodes. Furthermore, the term "electrode plate" may collectively refer to positive and negative plates.

[0021] (Overall battery configuration) Fig. 1 is a front view of a secondary battery 1 according to the present embodiment. Figs. 2 to 4 are views of the secondary battery 1 shown in Fig. 1 as viewed from the directions of arrows II, III, and IV, respectively. Fig. 5 is a front cross-sectional view of the secondary battery 1 shown in Fig. 1.

[0022] The secondary battery 1 can be mounted in an electric vehicle (BEV: Battery Electric Vehicle), a plug-in hybrid electric vehicle (PHEV: Plug-in Hybrid Electric Vehicle), a hybrid electric vehicle (HEV: Hybrid Electric Vehicle), etc. However, the use of the secondary battery 1 is not limited to being mounted in a vehicle.

[0023] 1 to 5, the secondary battery 1 includes an exterior body 100, an electrode assembly 200, and a current collector 300. The exterior body 100 includes a case main body 110, a sealing plate 121 (first sealing plate), and a sealing plate 122 (second sealing plate).

[0024] In this specification, the X-axis direction (first direction) shown in Figures 1 to 5 may be referred to as the "width direction" of the secondary battery 1 or the case body 110, the Y-axis direction (second direction) may be referred to as the "thickness direction" of the secondary battery 1 or the case body 110, and the Z-axis direction (third direction) may be referred to as the "height direction" of the secondary battery 1 or the case body 110.

[0025] When configuring a battery pack including the secondary batteries 1, multiple secondary batteries 1 are stacked in their thickness direction. The stacked secondary batteries 1 may be constrained in the stacking direction (Y-axis direction) by a constraining member to form a battery module, or the battery pack may be directly supported on the side surface of the battery pack case without using a constraining member.

[0026] The case body 110 is made of a cylindrical, preferably rectangular, member. This results in a rectangular secondary battery 1. The case body 110 is made of metal. Specifically, the case body 110 is made of aluminum, an aluminum alloy, iron, an iron alloy, or the like.

[0027] As shown in Figures 1 and 2, sealing plates 121, 122 are provided at both ends of the case body. The case body 110 can be formed into a rectangular tube shape, for example, by abutting the edges of bent plate-like members (joint 110A shown in Figure 2) and joining them together (for example, by laser welding). The corners of the "rectangular tube" may be rounded.

[0028] In this embodiment, the case body 110 is formed so that it is longer in the width direction (X-axis direction) of the secondary battery 1 than in the thickness direction (Y-axis direction) and height direction (Z-axis direction) of the secondary battery 1. The dimension (width) of the case body 110 in the X-axis direction is preferably about 30 cm or more. This allows for the construction of a relatively large (high-capacity) secondary battery 1. The dimension (height) of the case body 110 in the Z-axis direction is preferably about 20 cm or less, more preferably about 15 cm or less, and even more preferably about 10 cm or less. This allows for the construction of a relatively low-height secondary battery 1, which improves, for example, the mountability in a vehicle.

[0029] As shown in Fig. 3, an opening 111 (first opening) is provided at one end of the case body 110. The opening 111 is sealed by a sealing plate 121. The sealing plate 121 is provided with a positive electrode terminal 131 (first electrode terminal), a liquid inlet hole 141, and a gas release valve (not shown). The positions of the positive electrode terminal 131, the liquid inlet hole 141, and the gas release valve can be changed as appropriate. The opening 111 and the sealing plate 121 have a substantially rectangular shape with the Y-axis direction as the short side direction and the Z-axis direction as the long side direction.

[0030] As shown in Fig. 4, an opening 112 (second opening) is provided at one end of the case body 110. The opening 112 is sealed by a sealing plate 122. The sealing plate 122 is provided with a negative electrode terminal 132 (second electrode terminal), a liquid inlet 142, and a gas release valve (not shown). The positions of the negative electrode terminal 132, the liquid inlet 142, and the gas release valve can be changed as appropriate. The opening 112 and the sealing plate 122 have a substantially rectangular shape with the Y-axis direction as the short side direction and the Z-axis direction as the long side direction.

[0031] The sealing plates 121 and 122 are made of metal. Specifically, the sealing plates 121 and 122 are made of aluminum, an aluminum alloy, iron, an iron alloy, or the like.

[0032] The positive electrode terminal 131 is electrically connected to the positive electrode of the electrode assembly 200. The negative electrode terminal 132 is electrically connected to the negative electrode of the electrode assembly 200.

[0033] The positive electrode terminal 131 is made of a conductive material (more specifically, a metal), and may be made of, for example, aluminum or an aluminum alloy.

[0034] The negative electrode terminal 132 is made of a conductive material (more specifically, a metal), and may be made of, for example, copper or a copper alloy. The outer surface of the negative electrode terminal 132 may be provided with a portion or layer made of aluminum or an aluminum alloy.

[0035] The liquid injection holes 141, 142 are sealed with a sealing member (not shown). Examples of the sealing member that can be used include blind rivets and other metal members. The gas release valve breaks when the pressure inside the exterior body 100 reaches or exceeds a predetermined value, and releases the gas inside the exterior body 100 to the outside.

[0036] The electrode assembly 200 is a flat-shaped electrode assembly having positive and negative electrode plates, which will be described later. Specifically, the electrode assembly 200 is a wound-type electrode assembly in which a strip-shaped positive electrode plate and a strip-shaped negative electrode plate are wound together with a strip-shaped separator (not shown) interposed therebetween. However, in this specification, the "electrode assembly" is not limited to a wound-type electrode assembly, but may also be a stacked-type electrode assembly in which multiple positive electrode plates and multiple negative electrode plates are alternately stacked. The electrode assembly may include multiple positive electrode plates and multiple negative electrode plates, and the positive electrode tabs provided on each positive electrode plate may be stacked to form a positive electrode tab group, or the negative electrode tabs provided on each negative electrode plate may be stacked to form a negative electrode tab group.

[0037] 5, the exterior body 100 houses the electrode assembly 200. The electrode assembly 200 is housed in the exterior body 100 so that its winding axis is parallel to the X-axis direction.

[0038] Specifically, one or more wound electrode bodies are housed together with an electrolytic solution (electrolyte), not shown, inside an electrode body holder or insulating sheet (not shown) arranged within the exterior housing 100. The electrolytic solution (nonaqueous electrolytic solution) can be, for example, a nonaqueous solvent made by mixing ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) in a volume ratio (25°C) of 30:30:40, in which LiPF6 is dissolved at a concentration of 1.2 mol / L. Note that a solid electrolyte may be used instead of the electrolytic solution.

[0039] The electrode assembly 200 includes a positive electrode tab group 210A (first electrode tab group) provided on the end face (first end face) on the sealing plate 121 side, and a negative electrode tab group 220A (second electrode tab group) provided on the end face (second end face) on the sealing plate 122 side. The positive electrode tab group 210A and the negative electrode tab group 220A are electrically connected to the positive electrode and negative electrode of the electrode assembly 200, respectively. The positive electrode tab group 210A and the negative electrode tab group 220A are formed so as to protrude from a main body portion of the electrode assembly 200 (a portion where a positive electrode plate and a negative electrode plate are stacked with a separator interposed between them) toward the sealing plates 121, 122, respectively. The end face (first end face) on the sealing plate 121 side and the end face (second end face) on the sealing plate 122 side of the electrode assembly 200 extend in a direction substantially perpendicular to the X-axis direction.

[0040] The positive electrode tab group 210A includes a first portion 210A1 (first group) and a second portion 210A2 (second group) formed at a position spaced apart from the first portion 210A1 in the height direction (Z-axis direction). The negative electrode tab group 220A includes a first portion 220A1 (third group) and a second portion 220A2 (fourth group) formed at a position spaced apart from the first portion 220A1 in the height direction (Z-axis direction).

[0041] The current collector 300 includes a positive electrode current collector 310 (first current collector) and a negative electrode current collector 320 (second current collector). The positive electrode current collector 310 and the negative electrode current collector 320 are each made of a plate-shaped member. The electrode assembly 200 is electrically connected to a positive electrode terminal 131 and a negative electrode terminal 132 via the current collector 300.

[0042] The positive electrode current collector 310 is disposed on the sealing plate 121 via a resin insulating member 410. The positive electrode current collector 310 is electrically connected to the positive electrode tab group 210A and the positive electrode terminal 131. The positive electrode current collector 310 is made of a conductive material (more specifically, a metal), and may be made of, for example, aluminum or an aluminum alloy.

[0043] The negative electrode current collector 320 is disposed on the sealing plate 122 via a resin insulating member 420. The negative electrode current collector 320 is electrically connected to the negative electrode tab group 220A and the negative electrode terminal 132. The negative electrode current collector 320 is made of a conductive material (more specifically, a metal), and may be made of, for example, copper or a copper alloy.

[0044] (Configuration of electrode body 200) FIG. 6 is a front view showing a positive electrode plate 210S before the positive electrode plate 210 (first electrode) is formed, FIG. 7 is a cross-sectional view taken along line VII-VII of the positive electrode plate 210S shown in FIG. 6, and FIG. 8 is a front view showing the positive electrode plate 210 formed from the positive electrode plate 210S.

[0045] The positive electrode plate 210 is manufactured by processing a positive electrode original plate 210S. As shown in Figures 6 and 7, the positive electrode original plate 210S includes a positive electrode core 211, a positive electrode active material layer 212, and a positive electrode protective layer 213. The positive electrode core 211 is an aluminum foil or an aluminum alloy foil.

[0046] A positive electrode active material layer 212 is formed on both surfaces of the positive electrode core 211 except for one end portion. The positive electrode active material layer 212 is formed on the positive electrode core 211 by applying a positive electrode active material layer slurry using a die coater.

[0047] The positive electrode active material layer slurry is prepared by kneading lithium nickel cobalt manganese composite oxide as the positive electrode active material, polyvinylidene fluoride (PVdF) as a binder, a carbon material as a conductive material, and N-methyl-2-pyrrolidone (NMP) as a dispersion medium so that the mass ratio of lithium nickel cobalt manganese composite oxide:PVdF:carbon material is approximately 97.5:1:1.5.

[0048] The positive electrode protective layer 213 is in contact with the positive electrode core 211 and is formed on one end of the positive electrode active material layer 212 in the width direction. The positive electrode protective layer 213 is formed on the positive electrode core 211 by applying a positive electrode protective layer slurry using a die coater. The positive electrode protective layer 213 has a larger electrical resistance than the positive electrode active material layer 212.

[0049] The positive electrode protective layer slurry is prepared by kneading alumina powder, a carbon material as a conductive material, PVdF as a binder, and NMP as a dispersion medium so that the mass ratio of alumina powder:carbon material:PVdF is approximately 83:3:14.

[0050] The positive electrode substrate 211 coated with the positive electrode active material layer slurry and the positive electrode protective layer slurry is dried, and the NMP contained in the positive electrode active material layer slurry and the positive electrode protective layer slurry is removed, thereby forming the positive electrode active material layer 212 and the positive electrode protective layer 213. The positive electrode active material layer 212 is then compressed to form a positive electrode base plate 210S including the positive electrode substrate 211, the positive electrode active material layer 212, and the positive electrode protective layer 213. The positive electrode base plate 210S is cut into a predetermined shape to form the positive electrode plate 210. The positive electrode base plate 210S can be cut by laser processing using energy beam irradiation, mold processing, cutter processing, or the like.

[0051] As shown in FIG. 8, a plurality of positive electrode tabs 210B each made of a positive electrode core 211 are provided at one end in the width direction of a positive electrode plate 210 formed from a positive electrode original plate 210S. When the positive electrode plate 210 is wound, the plurality of positive electrode tabs 210B are stacked to form a positive electrode tab group 210A. The position and length in the protruding direction of each of the plurality of positive electrode tabs 210B are adjusted as appropriate, taking into account the state in which the positive electrode tab group 210A is connected to the positive electrode current collector 310. The shape of the positive electrode tabs 210B is not limited to the example shown in FIG. 8.

[0052] The base of each of the plurality of positive electrode tabs 210B is provided with a positive electrode protective layer 213. The positive electrode protective layer 213 does not necessarily have to be provided at the base of the positive electrode tab 210B.

[0053] FIG. 9 is a front view showing the negative electrode plate 220S before the negative electrode plate 220 (second electrode) is formed, FIG. 10 is a cross-sectional view of the negative electrode plate 220S shown in FIG. 9 taken along line XX, and FIG. 11 is a front view showing the negative electrode plate 220 formed from the negative electrode plate 220S.

[0054] The negative electrode plate 220 is manufactured by processing a negative electrode original plate 220S. As shown in Figures 9 and 10, the negative electrode original plate 220S includes a negative electrode core 221 and a negative electrode active material layer 222. The negative electrode core 221 is a copper foil or a copper alloy foil.

[0055] A negative electrode active material layer 222 is formed on both surfaces of the negative electrode substrate 221 except for one end portion. The negative electrode active material layer 222 is formed by applying a negative electrode active material layer slurry using a die coater.

[0056] The negative electrode active material layer slurry is prepared by kneading graphite as the negative electrode active material, styrene butadiene rubber (SBR) and carboxymethyl cellulose (CMC) as binders, and water as a dispersion medium so that the mass ratio of graphite:SBR:CMC is approximately 98:1:1.

[0057] The negative electrode substrate 221 coated with the negative electrode active material layer slurry is dried to remove water contained in the negative electrode active material layer slurry, thereby forming the negative electrode active material layer 222. The negative electrode active material layer 222 is then compressed to form a negative electrode base plate 220S including the negative electrode substrate 221 and the negative electrode active material layer 222. The negative electrode base plate 220S is cut into a predetermined shape to form the negative electrode plate 220. The negative electrode base plate 220S can be cut by laser processing using energy beam irradiation, mold processing, cutter processing, or the like.

[0058] As shown in Fig. 11, a plurality of negative electrode tabs 220B each made of a negative electrode core 221 is provided at one widthwise end of a negative electrode plate 220 formed from a negative electrode original plate 220S. When the negative electrode plate 220 is wound, the plurality of negative electrode tabs 220B are stacked to form a negative electrode tab group 220A. The position and length in the protruding direction of each of the plurality of negative electrode tabs 220B are adjusted as appropriate, taking into account the state in which the negative electrode tab group 220A is connected to the negative electrode current collector 320. The shape of the negative electrode tabs 220B is not limited to the example shown in Fig. 11.

[0059] In a typical example, the thickness of the negative electrode tab 220B (one piece) is smaller than the thickness of the positive electrode tab 210B (one piece). In this case, the thickness of the negative electrode tab group 220A is smaller than the thickness of the positive electrode tab group 210A.

[0060] In one example of a secondary battery 1, the number of positive electrode tabs 210B included in the positive electrode tab group 210A is preferably 0.5 times or more, more preferably 0.8 times or more, and even more preferably 0.9 times or more, the number of stacked positive electrode plates 210 (the number of layers stacked in the thickness direction in the case of a wound type).

[0061] Similarly, the number of negative electrode tabs 220B included in the negative electrode tab group 220A is preferably 0.5 times or more, more preferably 0.8 times or more, and even more preferably 0.9 times or more the number of stacked negative electrode plates 220 (the number of layers stacked in the thickness direction in the case of a wound type).

[0062] (Connection structure between electrode body 200 and positive electrode current collector 310) Fig. 12 is a diagram showing the connection structure between the positive electrode tab group 210A and the positive electrode current collector 310. As shown in Fig. 12, the electrode body 200 is formed by stacking two electrode bodies 201 and 202, each of which is a wound electrode body. The example shown in Fig. 12 shows a structure in which two wound electrode bodies are stacked, but the electrode body 200 may be composed of one wound electrode body, three or more wound electrode bodies, or a stacked electrode body.

[0063] The positive electrode current collector 310 is provided on the inner surface side of the sealing plate 121 and is connected to the electrode body 200 and the positive electrode terminal 131. The positive electrode current collector 310 includes a first conductive member 311 (first component) and a second conductive member 312 (second component). The first conductive member 311 and the second conductive member 312 are joined at a joint 313. The first conductive member 311 and the second conductive member 312 are attached to the inner surface side of the sealing plate 121 via an insulating member 410 made of resin.

[0064] The first portion 210A1 of the positive electrode tab group 210A is provided on the electrode body 201. The second portion 210A2 of the positive electrode tab group 210A is provided on the electrode body 202. The first conductive member 311 of the positive electrode current collector 310 includes a first portion 3111 joined to the first portion 210A1 of the positive electrode tab group 210A, and a second portion 3112 joined to the second portion 210A2 of the positive electrode tab group 210A.

[0065] First portion 3111 and second portion 3112 of first conductive member 311 are respectively joined to second conductive member 312 at joints 3131 and 3132. Joints 3131 and 3132 may be formed by, for example, ultrasonic bonding, resistance welding, laser welding, caulking, or the like.

[0066] The first portion 210A1 of the positive electrode tab group 210A includes a root portion 210A11 located on the root side, and a joint portion 210A21 located on the tip side and joined to the first portion 3111 of the first conductive member 311. The second portion 210A2 of the positive electrode tab group 210A includes a root portion 210A12 located on the root side, and a joint portion 210A22 located on the tip side and joined to the second portion 3112 of the first conductive member 311.

[0067] 12 shows the shape of the positive electrode tab group 210A before it is curved, but in the completed secondary battery 1, the positive electrode tab group 210A is housed in the case body 110 with the portion (curved portion) between the base portions 210A11, 210A11 and the joint portions 210A21, 210A22 curved around the Z axis. Before housing the electrode body 200 in the case body 110, it is preferable to curve (shape) the positive electrode tab group 210A to a state close to its final shape.

[0068] The second conductive member 312 of the positive electrode current collector 310 is joined at a joint 131A to a positive electrode terminal 131 provided so as to reach from the outside to the inside of the sealing plate 121. The joint 131A can be formed by, for example, ultrasonic bonding, resistance welding, laser welding, crimping, or the like.

[0069] The procedure for assembling the components is as follows: first, the positive electrode terminal 131 and the second conductive member 312 are attached to the sealing plate 121 together with the insulating member 410. Next, the first conductive member 311 connected to the electrode body 200 is attached to the second conductive member 312. At this time, the first conductive member 311 is placed on the insulating member 410 so that a portion of the first conductive member 311 overlaps the second conductive member 312. Next, the first conductive member 311 and the second conductive member 312 are connected by welding at the joint 313.

[0070] However, the positive electrode terminal 131 may be electrically connected to the sealing plate 121. Also, the sealing plate 121 may serve as the positive electrode terminal 131.

[0071] The insulating member 410 is disposed between the sealing plate 121 and the electrode assembly 200. The insulating member 410 is provided on the sealing plate 121 so as to overlap with the gas release valve. A slit portion 411 (through hole) is formed in the region of the insulating member 410 that overlaps with the gas release valve (in the example of FIG. 12, the region located between the bonding portions 210A21 and 210A22). This allows the insulating member 410 to be provided without impeding the function of the gas release valve. The slit portion 411 need only communicate between the internal space of the exterior body 100 and the gas release valve, and is not limited to the slit portion 411 shown in FIG. 12. For example, a notch may be provided in the insulating member 410 instead of a through hole.

[0072] The gas release valve is preferably disposed in a region that does not face the positive electrode current collector 310 over about 70% or more (more preferably about 80% or more, and even more preferably about 90% or more) of its area.

[0073] In Figure 12, an example is shown of a positive electrode current collector 310 made up of three parts (the first part 3111 and the second part 3112 of the first conductive member 311 and the second conductive member 312), but the first part 3111 and the second part 3112 of the first conductive member 311 may be formed integrally, or the positive electrode current collector 310 may be made up of a single part.

[0074] Although FIG. 12 shows the connection structure on the positive electrode side, the basic connection structure on the negative electrode side is the same as that on the positive electrode side.

[0075] (Example of electrode tab arrangement) 13 to 16 are diagrams showing examples of the arrangement of the root portions 210A10 of the positive electrode tab group 210A. All of Fig. 13 to Fig. 16 show examples of the arrangement of the root portions 210A10 of the positive electrode tab group 210A on the end face (first end face) of the electrode body 200 when viewed from the positive electrode side.

[0076] 13 is composed of a root portion 210A11 of a first portion 210A1 protruding from the electrode body 201 and a root portion 210A12 of a second portion 210A2 protruding from the electrode body 202. As shown in FIG.

[0077] 13 are located on opposite sides of the Y0 axis passing through the center of the height direction (Z-axis direction) of the electrode body 200, and are located on opposite sides of the Z0 axis passing through the boundary between the electrode bodies 201 and 202, i.e., the center of the thickness direction (Y-axis direction) of the electrode body 200. More specifically, the root portions 210A11 and 210A12 are arranged point-symmetrically with respect to the intersection of the Y0 axis and the Z0 axis.

[0078] The base portion 210A10 shown in FIG. 14 is composed of a first portion 210A1, a second portion 210A2, and base portions 210A11 and 210A12 that protrude from a single electrode body 200.

[0079] 14 are located on opposite sides of the Y0 axis passing through the center of the height direction (Z-axis direction) of the electrode body 200, and are located on opposite sides of the Z1 axis passing through the center of the thickness direction (Y-axis direction) of the electrode body 200. More specifically, the root portions 210A11 and 210A12 are arranged point-symmetrically with respect to the intersection of the Y0 axis and the Z1 axis.

[0080] The base portion 210A10 shown in FIG. 15 is made up of base portions 210A11 of two first portions 210A1 that protrude from the electrode assemblies 201 and 202, respectively, and base portions 210A12 of two second portions 210A2 that protrude from the electrode assemblies 201 and 202, respectively.

[0081] 15 are located on opposite sides of the Y0 axis passing through the center of the height direction (Z-axis direction) of the electrode body 200 within each of the electrode bodies 201 and 202, and are located on opposite sides of the Z1 axis and Z2 axis passing through the center of the thickness direction (Y-axis direction) of each of the electrode bodies 201 and 202. More specifically, the root portions 210A11 and 210A12 are arranged point-symmetrically with respect to the intersections of the Y0 axis with the Z1 axis and the Z2 axis.

[0082] 16 is composed of root portions 210A11 of three first portions 210A1 protruding from the electrode assemblies 201, 202, and 203, respectively, and root portions 210A12 of three second portions 210A2 protruding from the electrode assemblies 201, 202, and 203, respectively.

[0083] 16 are located on opposite sides of the Y0 axis passing through the center of the height direction (Z-axis direction) of the electrode body 200 within each of the electrode bodies 201, 202, 203, and are also located on opposite sides of the Z1 axis, Z2 axis, and Z3 axis passing through the center of the thickness direction (Y-axis direction) of each of the electrode bodies 201, 202, 203. More specifically, the root portions 210A11, 210A12 are arranged point-symmetrically with respect to each of the intersections of the Y0 axis with the Z1 axis, the Z2 axis, and the Z3 axis.

[0084] 17 and 18 are diagrams showing an example of the shape of the positive electrode tab group 210A. In the example shown in FIGS. 17 and 18, the first portion 210A1 and the second portion 210A2 each have a shape symmetrical with respect to the X-axis. Furthermore, the first portion 210A1 and the second portion 210A2 are arranged so as to be line-symmetrical with respect to the X-axis. By adopting the shapes shown in FIGS. 17 and 18, it is possible to effectively suppress variations in current density.

[0085] 19 and 20 are diagrams showing other examples of the shape of the positive electrode tab group 210A. In the examples shown in FIGS. 19 and 20, the first portion 210A1 and the second portion 210A2 each have an asymmetric shape with respect to the X axis, but the first portion 210A1 and the second portion 210A2 are arranged so as to be line-symmetric with each other with respect to the X axis. By adopting the shapes shown in FIGS. 19 and 20, it is possible to provide more space in the Z-axis direction for arranging the positive electrode tab group 210A.

[0086] (Manufacturing process of secondary battery 1) 21 is a flow diagram showing each step of the manufacturing method of the secondary battery 1. As shown in Fig. 21, in S10, the case body 110 is prepared. Next, in S20, the electrode body 200 is fabricated. In S30, the electrode terminals on the sealing plates 121, 122 are electrically connected to the electrode tab group of the electrode body 200, and in S40, the electrode body 200 is inserted into the case body 110.

[0087] In the example of Figure 21, first the negative electrode terminal 132 and the negative electrode tab group 220A are electrically connected (S31), then the electrode body 200 is inserted into the case body 110 (S40), and then the positive electrode terminal 131 and the positive electrode tab group 210A are electrically connected (S32).

[0088] After the connection of the electrode terminals and the electrode tab group (S30) and the insertion of the electrode body 200 (S40) are completed, the openings 111 and 112 are sealed with the sealing plates 121 and 122, respectively (S50). The sealing step with the sealing plates 121 and 122 is performed by, for example, laser welding.

[0089] In the present technology, the order of connecting the negative electrode terminal 132 and the negative electrode tab group 220A (S31), connecting the positive electrode terminal 131 and the positive electrode tab group 210A (S32), and inserting the electrode body 200 (S40) is not limited to the example in Fig. 21 and can be changed as appropriate. For example, there is also a case where the connection (S31) between the negative electrode terminal 132 and the negative electrode tab group 220A is performed after the connection (S32) between the positive electrode terminal 131 and the positive electrode tab group 210A is performed.

[0090] 21, the step (S51) of sealing opening 111 with sealing plate 121 on the positive electrode side is performed, followed by the step (S52) of sealing opening 112 with sealing plate 122 on the negative electrode side, but the step (S51) of sealing opening 111 with sealing plate 121 may be performed after the step (S52) of sealing opening 112 with sealing plate 122. Furthermore, at least some of the steps (S51, S52) of sealing with sealing plates 121, 122 may be performed simultaneously.

[0091] (summary) The above-described contents of the secondary battery 1 and the manufacturing method thereof according to this embodiment can be summarized as follows.

[0092] The secondary battery 1 includes a flat electrode assembly 200 that includes a positive electrode plate 210 (first electrode) and a negative electrode plate 220 (second electrode) having a polarity different from that of the positive electrode plate 210, and has a positive electrode tab group 210A (first electrode tab group) electrically connected to the positive electrode plate 210 (first electrode) on one end face (first end face) in the X-axis direction, and a negative electrode tab group 220A (second electrode tab group) electrically connected to the negative electrode plate 220 (second electrode) on the other end face (second end face) in the X-axis direction, an exterior body 100 (case) that houses the electrode assembly 200, a positive electrode current collector 310 (first current collector) electrically connected to the positive electrode tab group 210A, and a negative electrode current collector 320 (second current collector) electrically connected to the negative electrode tab group 220A. The outer casing 100 includes a case main body 110 having an opening 111 (first opening) and an opening 112 (second opening) opposite the opening 111, a sealing plate 121 (first sealing plate) having a positive electrode terminal 131 (first electrode terminal) provided therein and sealing the opening 111, and a sealing plate 122 (second sealing plate) having a negative electrode terminal 132 (second electrode terminal) provided therein and sealing the opening 112, both end faces of the electrode body 200 have a shape in which the Y-axis direction (second direction) is the short side direction and the Z-axis direction (third direction) is the long side direction, and the positive electrode tab group 210A includes a first portion 210A1 (first group) and a second portion 210A2 (second group) spaced apart from the first portion 210A1. The first portion 210A1 and the second portion 210A2 each have a root portion 210A11, 210A12, a joint portion 210A21, 210A22 joined to the positive electrode current collector 310, and a curved portion between the root portion 210A11, 210A12 and the joint portion 210A21, 210A22, and the root portions 210A11, 210A12 are located on opposite sides of each other with respect to the Y-axis direction (Y0-axis) and are also located on opposite sides of each other with respect to the Z-axis direction (Z0-axis, Z1-axis, Z2-axis, Z3-axis).

[0093] The negative electrode tab group 220A includes a first portion 220A1 (third group) and a second portion 220A2 (fourth group) spaced apart from the first portion 220A1. The first portion 220A1 and the second portion 220A2 of the negative electrode tab group 220A may also have a structure similar to the first portion 210A1 and the second portion 210A2 of the positive electrode tab group 210A.

[0094] As shown in FIG. 21 , the method for manufacturing the secondary battery 1 includes a step (S10) of preparing a case body 110 having an opening 111 and an opening 112 opposite to the opening 111, a positive electrode plate 210 (first electrode), and a negative electrode plate 220 (second electrode) having a polarity different from that of the positive electrode plate 210, and having a positive electrode tab group 210A (first electrode tab group) electrically connected to the positive electrode plate 210 (first electrode) on one end face (first end face) side in the X-axis direction, and a negative electrode plate 220 (second electrode) the electrode body 200 has, on the other end face (second end face) in the X-axis direction, a negative electrode tab group 220A (second electrode tab group) electrically connected to the electrode terminals on the sealing plates 121, 122; a step (S30) of electrically connecting the electrode tab group of the electrode body 200 to electrode terminals on the sealing plates 121, 122; a step (S40) of inserting the electrode body 200 into the case body 110; and a step (S50) of sealing the openings 111, 112 with the sealing plates 121, 122, respectively.

[0095] The step (S30) of electrically connecting the electrode terminals on the sealing plates 121, 122 and the electrode tab group of the electrode body 200 includes a step (S31) of electrically connecting the negative electrode terminal 132 and the negative electrode tab group 220A via the negative electrode current collector 320, and a step (S32) of inserting the electrode body 200 into the case body 110 and then electrically connecting the positive electrode terminal 131 provided on the sealing plate 121 and the positive electrode tab group 210A via the positive electrode current collector 310.

[0096] (Action and effect) According to the secondary battery 1 of this embodiment, the electrode body 200 is inserted into the case body 110 having openings 111 and 112 facing each other, and the positive terminal 131 and the negative terminal 132 are respectively provided on the sealing plates 121 and 122 that seal the openings 111 and 112, thereby reducing the height of the secondary battery 1 and improving the mountability of the secondary battery 1 in a vehicle.

[0097] Furthermore, by forming the positive electrode tab group 210A separately into the first portion 210A1 and the second portion 210A2, the output and regeneration characteristics of the secondary battery can be improved.

[0098] Furthermore, by arranging the root portions 210A11, 210A12 of the first portion 210A1 and the second portion 210A2 of the positive electrode tab group 210A on opposite sides of each other with respect to two axes (the Y0 axis and the Z0 to Z3 axes) and by bending the first portion 210A1 and the second portion 210A2 before joining them to the positive electrode current collector 310, it is possible to save space around the positive electrode current collector 310. Furthermore, by employing a similar structure on the negative electrode side, it is possible to save space around the negative electrode current collector 320. As a result, the area of ​​the electrode assembly 200 within the exterior body 100 can be expanded.

[0099] As described above, the secondary battery 1 and the manufacturing method thereof according to the present embodiment can provide a secondary battery having high energy density and excellent output and regeneration characteristics, as well as a manufacturing method thereof.

[0100] Although the embodiments of the present technology have been described above, the embodiments disclosed herein should be considered to be illustrative and not restrictive in all respects. The scope of the present technology is defined by the claims, and it is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0101] 1 secondary battery, 100 outer casing, 110 case body, 110A, 210A21, 210A22 joint, 111, 112 opening, 121, 122 sealing plate, 131 positive electrode terminal, 131A joint, 132 negative electrode terminal, 141, 142 liquid injection hole, 200, 201, 202, 203 electrode body, 210 positive electrode plate, 210A positive electrode tab group, 210A1 first part, 210A2 second part, 210A10, 210A11, 210A12 base part, 210A21, 210A22 joint, 210B positive electrode tab, 210S positive electrode base plate, 211 positive electrode core, 212 positive electrode active material layer, 213 positive electrode protective layer, 220 Negative electrode plate, 220A negative electrode tab group, 220A1 first portion, 220A2 second portion, 220B negative electrode tab, 220S negative electrode base plate, 221 negative electrode core, 222 negative electrode active material layer, 300 current collector, 310 positive electrode current collector, 311 first conductive member, 3111 first portion, 3112 second portion, 312 second conductive member, 313, 3131, 3132 joint portion, 320 negative electrode current collector, 410 insulating member, 411 slit portion.

Claims

1. an electrode body having a first end face located at one end side in a first direction and a second end face located at the other end side in the first direction, the electrode body including a first electrode and a second electrode having a polarity different from that of the first electrode, the electrode body having a first electrode tab group electrically connected to the first electrode at the first end face side, and a second electrode tab group electrically connected to the second electrode at the second end face side; a case for accommodating the electrode assembly; a first current collector electrically connected to the first electrode tab group; a second current collector electrically connected to the second electrode tab group, The case is a case body having a first opening and a second opening opposite the first opening; a first sealing plate provided with a first electrode terminal and sealing the first opening; a second sealing plate provided with a second electrode terminal and sealing the second opening; the first end surface and the second end surface have a shape in which a second direction substantially perpendicular to the first direction is a short-side direction, and a third direction substantially perpendicular to the first direction and the second direction is a long-side direction, the first electrode tab group includes a first group and a second group spaced apart from the first group; each of the first group and the second group has a root portion, a curved portion located closer to a tip end than the root portion, and a joint portion located closer to the tip end than the curved portion and joined to the first current collector; the root portions of the first group and the second group are located on opposite sides of each other with respect to the axis in the second direction and are located on opposite sides of each other with respect to the axis in the third direction; a gas exhaust valve provided in the first sealing plate; an insulating member disposed between the first sealing plate and the electrode body so that at least a portion of the insulating member overlaps with the gas release valve; When viewed from the first direction, the insulating member has a notch or a through-hole in a region overlapping with the gas release valve.

2. the second electrode tab group includes a third group and a fourth group spaced apart from the third group, the third group and the fourth group each have a root portion, a curved portion located closer to a tip end than the root portion, and a joint portion located closer to the tip end than the curved portion and joined to the second current collector; The secondary battery according to claim 1 , wherein the root portions of the third group and the fourth group are located on opposite sides of the axis in the second direction and are located on opposite sides of the axis in the third direction.

3. preparing a case body having a first opening and a second opening opposite the first opening; a process for producing a flat electrode body having a first end face located at one end side in a first direction and a second end face located at the other end side in the first direction, the electrode body including a first electrode and a second electrode having a polarity different from that of the first electrode, a first electrode tab group electrically connected to the first electrode on the first end face side, and a second electrode tab group electrically connected to the second electrode on the second end face side; attaching a first electrode terminal and an insulating member to a first sealing plate; inserting the electrode body into the case body; a step of inserting the electrode body into the case body, and then electrically connecting the first electrode terminals provided on the first sealing plate to the first electrode tab group via a first current collector; a step of electrically connecting second electrode terminals provided on a second sealing plate to the second electrode tab group via a second current collector; a step of sealing the first opening with the first sealing plate after electrically connecting the first electrode terminal and the first electrode tab group; and sealing the second opening with the second sealing plate after electrically connecting the second electrode terminal and the second electrode tab group. the first end surface and the second end surface have a shape in which a second direction substantially perpendicular to the first direction is a short-side direction, and a third direction substantially perpendicular to the first direction and the second direction is a long-side direction, the first electrode tab group includes a first group and a second group spaced apart from the first group; each of the first group and the second group has a root portion, a curved portion located closer to a tip end than the root portion, and a joint portion located closer to the tip end than the curved portion and joined to the first current collector; the root portions of the first group and the second group are located on opposite sides of each other with respect to the axis in the second direction and are located on opposite sides of each other with respect to the axis in the third direction; a gas exhaust valve is provided on the first sealing plate; The insulating member has a notch or a through hole, the insulating member is arranged so that a notch or a through hole is located in a region overlapping with the gas release valve when viewed from the first direction.

Images