Secondary batteries

Abstract

To improve the reliability of the joint connecting the case body and the sealing plate. [Solution] The case body 110 has an outer peripheral surface portion 116, a first end face 117, and a second end face 118. The outer peripheral surface portion 116 extends around an axis in a first direction. The first end face 117 is located at the end of the first side and extends in a direction intersecting the first direction. The second end face 118 is located at the end of the second side and extends in a direction intersecting the first direction. The first sealing plate 120 has a first covering portion 127. The first covering portion 127 covers at least a part of the first end face 117 from the first direction. The second sealing plate 130 has a second covering portion 137. The second covering portion 137 covers at least a part of the second end face 118 from the first direction. A first joint portion 140 is formed so as to straddle the outer peripheral surface portion 116 and the first covering portion 127. A second joint portion 141 is formed so as to span the outer peripheral surface portion 116 and the second covering portion 137.

Description

Technical Field

[0001] This technology relates to secondary batteries.

Background Art

[0002] As a prior art document disclosing the configuration of a secondary battery, there is Japanese Patent No. 4537353 (Patent Document 1). The secondary battery described in Patent Document 1 includes an electrode body, a case, and a cap plate. The electrode body is housed in the case. The case is provided with openings for inserting electrode groups at both ends. The cap plate is coupled to the openings. The cap plate is disposed inside the case to seal the openings.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the secondary battery described in Patent Document 1, it is impossible to position the sealing plate with respect to the case body, and there is a possibility that a joint portion for joining the case body and the sealing plate is not stably formed. Therefore, there is room for improving the reliability of the joint portion.

[0005] This technology has been made to solve the above problems, and an object thereof is to provide a secondary battery capable of improving the reliability of a joint portion for joining a case body and a sealing plate.

Means for Solving the Problems

[0006] The secondary battery according to this technology comprises an electrode body including a first electrode and a second electrode having a different polarity from the first electrode, and a case housing the electrode body, the case having a case body having a first opening located at the end of the first side in the first direction and a second opening located at the end of the second side opposite to the first side in the first direction, a first sealing plate sealing the first opening and a second sealing plate sealing the second opening, the case body having an outer peripheral surface portion extending around the axis in the first direction, a first end face located at the end of the first side and extending in a direction intersecting the first direction, and located at the end of the second side The first sealing plate has a second end face extending in a direction intersecting the first direction, and a first electrode terminal electrically connected to the first electrode is attached to the first sealing plate, and in the short direction of the first sealing plate, the first electrode terminal is off-center to one side from the center of the first sealing plate, the first sealing plate has a first covering portion that covers at least a part of the first end face from the first direction, the second sealing plate has a second covering portion that covers at least a part of the second end face from the first direction, a first joint portion is formed so as to straddle the outer peripheral surface portion and the first covering portion, and a second joint portion is formed so as to straddle the outer peripheral surface portion and the second covering portion. [Effects of the Invention]

[0007] This technology makes it possible to improve the reliability of the joint that connects the case body and the sealing plate. [Brief explanation of the drawing]

[0008] [Figure 1] This is a front view showing the configuration of a secondary battery according to one embodiment of this technology. [Figure 2] This figure shows the secondary battery shown in Figure 1 as viewed from the direction of arrow II. [Figure 3] This figure shows the secondary battery shown in Figure 1 as viewed from the direction of arrow III. [Figure 4] Figure 1 shows the secondary battery as viewed from the direction of arrow IV. [Figure 5] Figure 1 is a front cross-sectional view of a secondary battery. [Figure 6] This is a front view showing the negative electrode base plate before the negative electrode plate is formed. [Figure 7] Figure 6 is a cross-sectional view of the negative electrode plate along line VII-VII. [Figure 8] This is a front view showing a negative electrode plate formed from a negative electrode base plate. [Figure 9] This is a front view showing the positive electrode raw material before the positive electrode plate is formed. [Figure 10] Figure 9 shows a cross-sectional view of the positive electrode plate at XX. [Figure 11] This is a front view showing a positive electrode plate formed from a positive electrode base plate. [Figure 12] This diagram shows the electrode body and current collector removed from a secondary battery. [Figure 13] This is a front view of the connection structure between the negative electrode tab group and the negative electrode current collector. [Figure 14] This is a cross-sectional view of the connection structure between the negative electrode tab group and the negative electrode current collector. [Figure 15] This diagram shows the process of inserting the electrode into the case body. [Figure 16] This diagram shows the process of placing a spacer between the sealing plate and the electrode body. [Figure 17] This is a cross-sectional view showing the joint portion of the case of a secondary battery according to one embodiment. [Figure 18] This is a perspective view showing the bonding state between the case body and the first sealing plate of the secondary battery according to the comparative example. [Figure 19] This is a flowchart showing a method for manufacturing a secondary battery according to one embodiment. [Figure 20] This is a bottom view showing the joining method used when molding the case body. [Figure 21] This is a bottom view showing a joining method when molding the case body according to a first modified example of one embodiment. [Figure 22] This is a perspective view showing a method for joining the case body and the first sealing plate of a secondary battery according to one embodiment. [Figure 23] This is a side view showing the state immediately after the joining of the case body and the first sealing plate has begun. [Figure 24] It is a side view showing a state where the short side portions are joined while rotating the case body and the first sealing plate. [Figure 25] It is a side view showing a state where the long side portions are joined while rotating the case body and the first sealing plate. [Figure 26] It is a bottom view showing the joining path when joining the case body and the first sealing plate. [Figure 27] It is a bottom view showing the first welding path when joining the case body and the first sealing plate according to a modified example. [Figure 28] It is a bottom view showing the second welding path when joining the case body and the first sealing plate according to a modified example. [Figure 29] It is a bottom view showing the third welding path when joining the case body and the first sealing plate according to a modified example. [Figure 30] It is a perspective view showing the joined state of the case body and the first sealing plate of a secondary battery according to a second modified example of an embodiment.

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present technology will be described. In some cases, the same or corresponding parts may be denoted by the same reference numerals, and the description thereof may not be repeated.

[0010] In the embodiments described below, when referring to the number, quantity, etc., unless otherwise specified, the scope of the present technology is not necessarily limited to such number, quantity, etc. Also, in the following embodiments, each component is not necessarily essential for the present technology, unless otherwise specified. Further, the present technology is not necessarily limited to those that exhibit all the operational effects mentioned in the present embodiments.

[0011] In this specification, the descriptions of "comprise", "include", and "have" are in an open - ended format. That is, when including a certain configuration, other configurations outside the said configuration may or may not be included.

[0012] 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).

[0013] 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.

[0014] In the drawings, the direction along the winding axis of the electrode body of the secondary battery is designated as the X direction as the first direction, the Y direction is designated as the second direction as the direction perpendicular to the first direction and the short side of the electrode body as viewed from the first direction, and the Z direction is designated as the third direction as the direction perpendicular to the first direction and the long side of the electrode body as viewed from the first direction. Furthermore, in order to facilitate understanding of the invention, the dimensions of each component in the drawings have been changed from the actual dimensions in some cases.

[0015] 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.

[0016] (Overall battery configuration) Figure 1 is a front view of the secondary battery 1 according to this embodiment. Figures 2 to 4 show the secondary battery 1 shown in Figure 1 as viewed from the directions of arrows II, III, and IV, respectively. Figure 5 is a front cross-sectional view of the secondary battery 1 shown in Figure 1.

[0017] 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.

[0018] As shown in Figures 1 to 5, 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 first sealing plate 120, and a second sealing plate 130.

[0019] 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.

[0020] 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.

[0021] As shown in Figures 1 and 2, a first sealing plate 120 and a second sealing plate 130 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-shaped 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. In this embodiment, the joint portion 115 extends in a first direction (X direction) on the outer circumferential surface of the case body 110.

[0022] 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.

[0023] 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.

[0024] As shown in Figure 3, a first opening 113 is provided at the first side end of the case body 110 in the first direction (X direction). The first opening 113 is sealed by a first sealing plate 120. The first opening 113 and the first sealing plate 120 have a substantially rectangular shape with the Y direction being the short side and the Z direction being the long side.

[0025] The first sealing plate 120 is provided with a negative electrode terminal 301 (first electrode terminal), an injection hole 124, and a gas discharge valve 125. The positions of the negative electrode terminal 301, the injection hole 124, and the gas discharge valve 125 can be changed as appropriate.

[0026] As shown in Figure 4, a second opening 114 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). The second opening 114 is sealed by a second sealing plate 130. The second opening 114 and the second sealing plate 130 have a substantially rectangular shape, with the Y direction being the short side and the Z direction being the long side.

[0027] A positive electrode terminal 302 (second electrode terminal), an injection hole 134, and a gas discharge valve 135 are provided on the second sealing plate 130. The positions of the positive electrode terminal 302, the injection hole 134, and the gas discharge valve 135 can be changed as appropriate.

[0028] The first sealing plate 120 and the second sealing plate 130 are made of metal. Specifically, the first sealing plate 120 and the second sealing plate 130 are made of aluminum, aluminum alloy, iron, or iron alloy, etc.

[0029] In this embodiment, the thickness of the first sealing plate 120 and the second sealing plate 130 is greater than the thickness (plate thickness) of the case body 110. This reduces the thermal influence when forming the first joint 140 and the second joint 141, which will be described later, in the first sealing plate 120 and the second sealing plate 130, which occupy a smaller volume compared to the case body 110, and suppresses the formation of holes and other defects during joining.

[0030] The negative electrode terminal 301 is electrically connected to the negative electrode of the electrode body 200. The negative electrode terminal 301 is attached to the first sealing plate 120, i.e., the case 100.

[0031] The positive terminal 302 is electrically connected to the positive electrode of the electrode body 200. The positive terminal 302 is attached to the second sealing plate 130, i.e., the case 100.

[0032] The negative electrode terminal 301 is made of a conductive material (more specifically, a metal), such as copper or a copper alloy. A portion or layer made of aluminum or an aluminum alloy may be provided on the outer surface of the negative electrode terminal 301.

[0033] 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.

[0034] The injection holes 124 and 134 are sealed by a sealing member (not shown). For example, blind rivets and other metal members can be used as the sealing member.

[0035] The gas discharge valves 125 and 135 rupture when the pressure inside the case 100 exceeds a predetermined value, thereby discharging the gas inside the case 100 to the outside.

[0036] 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 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.

[0037] As shown in Figure 5, the case 100 houses the electrode body 200. The electrode body 200 is housed in the case 100 such that its winding axis is parallel to the X direction.

[0038] 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.

[0039] The electrode body 200 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 (first electrode tab group), and a positive electrode tab group 250 (second electrode tab group).

[0040] 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 electrode body 200 in the first direction (X direction) relative to the main body. In this embodiment, the first side is the side of the first sealing plate 120. The positive electrode tab group 250 is located at the second side end of the main body in the first direction (X direction). In this embodiment, the second side is the side of the second sealing plate 130.

[0041] 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 first sealing plate 120 or the second sealing plate 130, respectively.

[0042] The current collector 400 includes a negative electrode current collector 410 (first current collector) and a positive electrode current collector 420 (second current collector). The negative electrode current collector 410 and the positive electrode current collector 420 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.

[0043] The negative electrode current collector 410 is positioned on the first sealing plate 120 via a resin insulating member. The negative electrode current collector 410 is electrically connected to the negative electrode tab group 220 and the negative electrode terminal 301. The negative electrode current collector 410 is made of a conductive material (more specifically, a metal), which may be made of copper or a copper alloy, for example.

[0044] The positive electrode current collector 420 is positioned on the second sealing plate 130 via a resin insulating member. The positive electrode current collector 420 is electrically connected to the positive electrode tab group 250 and the positive electrode terminal 302. The positive electrode current collector 420 is made of a conductive material (more specifically, a metal), such as aluminum or an aluminum alloy. The positive electrode tab group 250 may be electrically connected to the second sealing plate 130 directly or via the positive electrode current collector 420. In this case, the second sealing plate 130 may also function as the positive electrode terminal 302.

[0045] (Configuration of electrode body 200) Figure 6 is a front view showing the negative electrode base plate 210S before the negative electrode plate 210 (first electrode) is formed, Figure 7 is a VII-VII cross-sectional view of the negative electrode base plate 210S shown in Figure 6, and Figure 8 is a front view showing the negative electrode plate 210 formed from the negative electrode base plate 210S.

[0046] The negative electrode plate 210 is manufactured by processing the negative electrode base plate 210S. As shown in Figures 6 and 7, the negative electrode base plate 210S includes a negative electrode core 211 and a negative electrode active material layer 212. The negative electrode core 211 is copper foil or copper alloy foil.

[0047] 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.

[0048] 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.

[0049] 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.

[0050] As shown in Figure 8, a plurality of negative electrode tabs 230, each 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 (first electrode). 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 410. Note that the shape of the negative electrode tabs 230 is not limited to that illustrated in Figure 8.

[0051] Figure 9 is a front view showing the positive electrode base plate 240S before the positive electrode plate 240 (second electrode) is formed, Figure 10 is a cross-sectional view of the positive electrode base plate 240S shown in Figure 9, and Figure 11 is a front view showing the positive electrode plate 240 formed from the positive electrode base plate 240S.

[0052] 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 9 and 10, the positive electrode base plate 240S includes a positive electrode core 241, 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.

[0053] 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] As shown in Figure 11, a plurality of positive electrode tabs 260, each made of a positive electrode core 241, are provided at one end in the width direction of the positive electrode plate 240 formed from the 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 (second electrode). 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 420. Note that the shape of the positive electrode tabs 260 is not limited to that shown in Figure 11.

[0059] A positive electrode protective layer 243 is provided at the base of each of the multiple positive electrode tabs 260. A positive electrode protective layer 243 is not necessarily provided at the base of the positive electrode tabs 260.

[0060] 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.

[0061] (Connection structure between electrode body 200 and current collector 400) Figure 12 shows the electrode body 200 and current collector 400 taken from the secondary battery 1. As shown in Figure 12, the electrode body 200 is formed by stacking two electrode bodies 201 and 202, each being a wound-type electrode body. In the example shown in Figure 12, a structure in which two wound-type electrode bodies are stacked is shown, but the electrode body 200 may be composed of one wound-type electrode body, or of three or more wound-type electrode bodies, or of a stacked electrode body.

[0062] The negative electrode tab group 220 is joined to the negative electrode current collector 410 at the joining point 434, and the positive electrode tab group 250 is joined to the positive electrode current collector 420 at the joining point 454.

[0063] Figure 13 is a front view of the connection structure between the negative electrode tab group and the negative electrode current collector. Figure 14 is a cross-sectional view of the connection structure between the negative electrode tab group and the negative electrode current collector.

[0064] As shown in Figures 13 and 14, the negative electrode current collector 410 electrically connects the negative electrode terminal 301 and the negative electrode tab group 220. In this embodiment, the negative electrode current collector 410 is connected to the negative electrode terminal 301 between the electrode body 200 and the first sealing plate 120.

[0065] The negative electrode current collector 410 includes a first conductive member 430 and a second conductive member 440. The first conductive member 430 and the second conductive member 440 are joined at a joint 433. The first conductive member 430 and the second conductive member 440 are joined, for example, by laser welding.

[0066] The first conductive member 430 is joined to the negative electrode tab group 220 at the joining point 434. The joining point 434 can be formed by, for example, ultrasonic welding, resistance welding, laser welding, crimping, etc. In this embodiment, the first conductive member 430 and the negative electrode tab group 220 are joined by, for example, ultrasonic bonding.

[0067] The second conductive member 440 is connected to the negative electrode terminal 301 at a joint 441. The joint 441 can be formed by, for example, ultrasonic welding, resistance welding, laser welding, crimping, etc. In this embodiment, the joining of the negative electrode terminal 301 and the second conductive member 440 is performed, for example, by providing a through hole in the second conductive member 440, inserting the negative electrode terminal 301 into the through hole, crimping the negative electrode terminal 301 on the second conductive member 440, and then welding the crimped portion to the second conductive member 440.

[0068] The first conductive member 430 has a first planar portion 431 and a second planar portion 432. The first planar portion 431 is connected to the second conductive member 440. The second planar portion 432 is connected to the negative electrode tab group 220. The second planar portion 432 is positioned along the first sealing plate 120.

[0069] A stepped portion 435 is provided between the first planar portion 431 and the second planar portion 432. The stepped portion 435 causes the positions of the first planar portion 431 and the second planar portion 432 in the first direction (X direction) to differ when the secondary battery 1 is assembled. This allows the first planar portion 431 and the second planar portion 432 to be arranged side by side in one direction. The stepped portion 435 extends along the third direction (Z direction).

[0070] A first insulating member 510 (resin material) is placed between the negative terminal 301 and the first sealing plate 120. A second insulating member 520 (resin material) is placed between the first sealing plate 120 and the first conductive member 430 and the second conductive member 440. Note that the first insulating member 510 and the second insulating member 520 may be a single integrated component.

[0071] The negative electrode terminal 301 is attached to the first sealing plate 120 via the first insulating member 510. The negative electrode terminal 301 is exposed on the outside of the first sealing plate 120 and is positioned to reach the second conductive member 440 of the negative electrode current collector 410, which is provided on the inner surface side of the first sealing plate 120.

[0072] The assembly procedure for each component is as follows: First, the negative electrode terminal 301 and the second conductive member 440 are attached to the first sealing plate 120 together with the first insulating member 510 and the second insulating member 520. Next, the first conductive member 430, which is electrically connected to the electrode body 200, is attached to the second conductive member 440. At this time, the first conductive member 430 is positioned on the first insulating member 510 such that a part of the first conductive member 430 overlaps with the second conductive member 440. Subsequently, the first conductive member 430 and the second conductive member 440 are welded together at the joint 434.

[0073] However, the negative terminal 301 may be electrically connected to the first sealing plate 120. Alternatively, the first sealing plate 120 may also function as the negative terminal 301.

[0074] In Figures 13 and 14, a negative electrode current collector 410 consisting of two parts (a first conductive member 430 and a second conductive member 440) is shown as an example, but the negative electrode current collector 410 may also be composed of a single part.

[0075] Figures 13 and 14 show the connection structure on the negative electrode side, but the basic connection structure on the positive electrode side is the same as that on the negative electrode side.

[0076] (Insertion process of electrode body 200) Figure 15 shows the process of inserting the electrode body 200 into the case body 110. As shown in Figure 15, a resin insulating sheet 700 (electrode body holder) is placed between the electrode body 200 and the case body 110.

[0077] The insulating sheet 700 may be made of, for example, a resin. More specifically, the material of the insulating sheet 700 may be, for example, polypropylene (PP), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyimide (PI), or polyolefin (PO).

[0078] 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.

[0079] Figure 16 shows the process of placing the first spacer 600 between the first sealing plate 120 and the electrode body 200.

[0080] As shown in Figure 16, the group of negative electrode tabs 220, which are positioned from the electrode body 200 toward the first sealing plate 120, are curved so as to bend from the center in the Y direction toward the edge of the first sealing plate 120, and then fold back toward the center. A first spacer 600 is provided to accommodate the curved portion of the group of negative electrode tabs 220. The first spacer 600 is positioned between the electrode body 200 and the first sealing plate 120.

[0081] The first spacer 600 includes a first component 610 and a second component 620. The first component 610 and the second component 620 engage with each other by engaging portions 630a and 630b by sliding them along the Y-direction from the end side to the center side of the first sealing plate 120, respectively. This fixes the first spacer 600 to the first sealing plate 120 via the second insulating member 520, increasing the stability of the position of the first spacer 600.

[0082] The secondary battery 1 according to this embodiment includes a second spacer (not shown). The second spacer is positioned between the electrode body and the second sealing plate. The second spacer may have the same structure as the first spacer 600. The first spacer 600 and the second spacer may also have different shapes.

[0083] (Joining structure between the case body 110 and the sealing plates 120, 130) Figure 17 is a cross-sectional view showing the joint of a case of a secondary battery according to one embodiment. Note that in Figure 17, components other than the case 100 are omitted to facilitate understanding of the invention.

[0084] As shown in Figure 17, the case body 110 has an outer peripheral surface portion 116, a first end surface 117, and a second end surface 118.

[0085] The outer circumferential surface portion 116 extends around an axis in the first direction (X direction). Furthermore, the outer circumferential surface portion 116 extends along the first direction (X direction). Although the outer circumferential surface portion 116 extends substantially parallel to the first direction (X direction), it may be inclined from the first direction (X direction) due to manufacturing errors in the case body 110. Additionally, irregularities or steps may be formed on the surface of the outer circumferential surface portion 116.

[0086] The first end face 117 is located at the end of the first side in the first direction (X direction). The first end face 117 extends in a direction intersecting the first direction (X direction). In this embodiment, the first end face 117 extends in a direction substantially perpendicular to the first direction (X direction). Because the first end face 117 extends in a direction substantially perpendicular to the first direction (X direction), the first sealing plate 120 can easily come into contact with it.

[0087] The second end face 118 is located at the end of the second side in the first direction (X direction). The second end face 118 extends in a direction intersecting the first direction (X direction). In this embodiment, the second end face 118 extends in a direction substantially perpendicular to the first direction (X direction). Because the second end face 118 extends in a direction substantially perpendicular to the first direction (X direction), the second sealing plate 130 can easily come into contact with it.

[0088] The first sealing plate 120 has a first covering portion 127. The first covering portion 127 covers at least a part of the first end face 117 from a first direction (X direction). This makes it easier to stably position the first sealing plate 120 relative to the case body 110. In this embodiment, the first covering portion 127 covers the entire surface of the first end face 117 from a first direction (X direction).

[0089] The second sealing plate 130 has a second covering portion 137. The second covering portion 137 covers at least a part of the second end face 118 from the first direction (X direction). Therefore, the second sealing plate 130 is easily positioned stably with respect to the case body 110. In this embodiment, the second covering portion 137 covers the entire surface of the second end face 118 from the first direction (X direction).

[0090] A first joint portion 140 is formed so as to span the outer peripheral surface portion 116 and the first covering portion 127. The first joint portion 140 joins the first end face 117 and the first covering portion 127. A second joint portion 141 is formed so as to span the outer peripheral surface portion 116 and the second covering portion 137. The second joint portion 141 joins the second end face 118 and the second covering portion 137. The first joint portion 140 and the second joint portion 141 are formed, for example, by laser welding. However, the first joint portion 140 and the second joint portion 141 are not limited to laser welding, and may be formed by other joining methods such as ultrasonic welding or resistance welding.

[0091] Since the first joint portion 140 and the second joint portion 141 are located on the outer peripheral surface portion 116 of the case body 110, they can be positioned further away from the resin insulating member provided between the electrode terminals 300 and the sealing plates 120, 130, compared to the case where the entire sealing plate is inserted into the inside of the case body and the joint portion is formed between the outer peripheral surface of the sealing plate and the end face of the case body. This reduces the thermal impact on the insulating member during joining.

[0092] The following describes a secondary battery relating to a comparative example. Since the case structure of this comparative example differs from that of secondary battery 1 relating to one embodiment of the present technology, the same configuration as secondary battery 1 relating to one embodiment of the present technology will not be repeated in the description.

[0093] Figure 18 is a perspective view showing the bonding state between the case body and the first sealing plate of the secondary battery according to the comparative example.

[0094] As shown in Figure 18, the secondary battery 9 according to the comparative example includes a case 900. The case 900 includes a case body 910 and a first sealing plate 920.

[0095] The case body 910 has a first end face 917 and an inner circumferential surface portion 919. The first end face 917 is located at the end of the first side in a first direction (X direction). The inner circumferential surface portion 919 extends inward around the axis of the case body 910 in the first direction (X direction).

[0096] The first sealing plate 920 covers the first opening 913. The outer periphery of the first sealing plate 920 is in contact with the inner circumferential surface 919 of the case body 910. The inner circumferential surface 919 and the outer periphery of the first sealing plate 920 are joined by a first joint 940. The first joint 940 is formed to straddle the outer surface of the first sealing plate 920 and the end face of the case body 910.

[0097] When forming the first joint 940, and inserting the first sealing plate 920 into the case body 910, the first sealing plate 920 can be positioned at any position in the first direction (X direction), making it difficult to determine the position of the first sealing plate 920 in the first direction (X direction).

[0098] On the other hand, as shown in Figure 17, in this embodiment, the first covering portion 127 of the first sealing plate 120 can be brought into contact with the first end face 117 of the case body 110, making it easier to position the first sealing plate 120 relative to the case body 110. This makes it easier to join the case body 110 and the first sealing plate 120. As a result, the first joint portion 140 can be formed stably.

[0099] The method for manufacturing a secondary battery according to this embodiment will be described below. Figure 19 is a flowchart showing the method for manufacturing a secondary battery according to one embodiment. Figure 20 is a bottom view showing the joining method when forming the case body. Note that the welding path in Figure 20 is shown offset from the actual welding area to make the welding path easier to understand.

[0100] As shown in Figure 19, the manufacturing method of the secondary battery 1 according to this embodiment is to first prepare the case body (step S1). In the step of preparing the case body 110 (step S1), a plate-shaped member is bent into a cylindrical shape, and the ends of the plate-shaped members bent into a cylindrical shape are joined to each other to form a rectangular cylindrical member that constitutes the case body 110.

[0101] In joining the ends of this plate-shaped member, the ends of the plate-shaped member can be welded by irradiating them with energy rays in multiple passes. However, it is not always necessary to divide the process into multiple passes. In this embodiment, the ends of the plate-shaped member are welded by irradiating them with a laser in two passes. This forms the joint 115.

[0102] Specifically, first, during the first laser irradiation, a laser (not shown) passes through the welding path 115a in Figure 20 in the direction of the arrow, and the first region R1, including the first side end of the case body 110, is welded. Next, during the second laser irradiation, the laser passes through the welding path 115b in Figure 20 in the direction of the arrow, and the second region R2, including the second side end of the case body 110, is welded.

[0103] In welding the first region R1 and the second region R2, the end of the first side and the end of the second side become the start or end point of the weld. In this embodiment, the end of the first side and the end of the second side become the end point of the weld.

[0104] In laser welding performed in two stages, the welding distance of one stage can be made longer than that of the other. In this embodiment, the welding path 115b for welding the second region R2 is longer than the welding path 115a for welding the first region R1. This makes the distance traveled from the end point of welding path 115a to the start point of welding path 115b shorter compared to when the welding distances are the same. As a result, the distance not irradiated by the laser can be shortened, and therefore the overall welding time can be shortened.

[0105] Figure 21 is a bottom view showing the joining method when molding the case body according to a first modified example of one embodiment.

[0106] In the first laser irradiation in this modified example, a laser (not shown) passes through the welding path 115c in Figure 21 in the direction of the arrow, welding the second region R2, which includes the second side end of the case body 110A. Next, in the second laser irradiation, the laser passes through the welding path 115d in Figure 21 in the direction of the arrow, welding the first region R1, which includes the first side end of the case body 110A. This forms the joint 115A.

[0107] In the method for joining the case body of the secondary battery according to this modified example, the end on the first side and the end on the second side serve as the starting points for welding. This makes it possible to more effectively suppress the flow of molten material during welding towards the opening side of the case body 110A, which would otherwise result in unstable contact with the sealing plate.

[0108] Next, as shown in Figure 19, the first electrode terminal and the electrode body are electrically connected (step S2). In this embodiment, the negative electrode tab group 220 of the electrode body 200 is electrically connected to the negative electrode terminal 301 (first electrode terminal) provided on the first sealing plate 120 via the negative electrode current collector 410.

[0109] Next, the group of positive electrode tabs 250 of the electrode body 200 is connected to the first conductive member 430 of the positive electrode current collector 420. This step may be performed after step S3, which will be described later.

[0110] Next, the electrode body 200 is inserted into the case body 110 (step S3). As shown in Figure 15, the electrode body 200 is inserted into the case body 110 by inserting the positive electrode current collector 420 through the first opening 113.

[0111] Next, the second electrode terminal and the electrode body are connected (step S4). In this embodiment, the group of positive electrode tabs 250 of the electrode body 200 is electrically connected to the positive electrode terminal 302 (second electrode terminal) provided on the second sealing plate 130 via the positive electrode current collector 420.

[0112] The first spacer 600 and the second spacer are placed between the electrode body 200 and the sealing plates 120 and 130 at any time during the process described above, after the electrode tabs have been bent.

[0113] Next, as shown in Figure 19, the case body 110 and the sealing plates 120 and 130 are temporarily joined together (step S5).

[0114] Before sealing the first opening 113, a portion covering at least a part of the first end face 117 of the first opening 113 (first covering portion 127) is temporarily joined to the first end face 117. The temporary joining is performed by joining the sealing plate and the case body at a point-like manner. In this embodiment, the temporary joining is formed, for example, by joining one point on each of the four sides of the pair of first side portions 111 and the pair of second side portions 112. The temporary joining may also be, for example, a relatively short (for example, less than 1 cm) linear. Furthermore, temporary joining is not necessarily required.

[0115] Figure 22 is a perspective view showing a method for joining the case body and the first sealing plate of a secondary battery according to one embodiment.

[0116] Next, as shown in Figure 22, the first opening 113 is sealed (step S6). Then, the second opening 114 is sealed (step S6).

[0117] At least a portion of the process of sealing the first opening 113 and the process of sealing the second opening 114 are performed simultaneously. In this embodiment, the process of sealing the first opening 113 and the process of sealing the second opening 114 are performed such that the start and end times are approximately the same.

[0118] Furthermore, the steps of sealing the first opening 113 and sealing the second opening 114 may overlap in some respects. Also, these steps may start and end at the same time, or they may start and end at the same time. If some of these steps overlap, the sealing of the first opening 113 and the sealing of the second opening 114 may be performed first.

[0119] The first sealing plate 120 is brought into contact with the first end face 117 so as to cover at least a portion of the first end face 117 from the first direction (X direction), and the first opening 113 is sealed by performing a joining process from the outer circumference side around the axis of the first direction (X direction) to form a joint that spans the first sealing plate 120 and the outer circumference portion 116 of the case body 110.

[0120] Similar to the joining of the first sealing plate 120, before the step of sealing the second opening 114, the portion that covers at least a part of the second end face 118 of the second opening 114 and the second end face 118 are temporarily joined. The second sealing plate 130 is brought into contact with the second end face 118 from the first direction (X direction) so as to cover at least a part of the second end face 118, and the joining process is performed from the outer circumference side around the axis of the first direction (X direction) to form a joint that spans the second sealing plate 130 and the outer circumference portion 116 of the case body 110, thereby sealing the second opening 114. Note that temporary joining is not necessarily required.

[0121] Figure 23 is a side view showing the state immediately after joining the case body and the first sealing plate has begun. Figure 24 is a side view showing the state of joining the short side portions while rotating the case body and the first sealing plate. Figure 25 is a side view showing the state of joining the long side portions while rotating the case body and the first sealing plate. Figure 26 is a bottom view showing the joining path when joining the case body and the first sealing plate. Figures 23 to 25 show only the case body. Also, Figures 23 to 26 illustrate the joining on the negative electrode side, and the same joining method can be used for joining on the positive electrode side. Note that the welding path in Figure 26 is shown shifted from the actual welding area to make the welding path easier to understand.

[0122] As shown in Figures 22 to 25, at least one of the steps of sealing the first opening 113 and sealing the second opening 114 can be performed by rotating the case body 110 around the axis in the first direction (X direction) (rotating in the r1 direction in Figure 22). In this embodiment, in both the step of sealing the first opening 113 and the step of sealing the second opening 114, the case body 110 is rotated and welding is performed with the laser 3. The laser 3 may be pulsed or continuous oscillation type.

[0123] The case body 110 is pressed by a gripping device (not shown) until it undergoes elastic deformation. This causes the electrode body 200 to be held between the case body 110. The case body 110 is pressed by the gripping device at the first side portion 111, which has a larger area than the second side portion 112. Note that the deformation of the case body 110 is not limited to elastic deformation. An insulating sheet 700 may also be interposed between the case body 110 and the electrode body 200.

[0124] In this embodiment, the case body 110 is subjected to the joining process while continuously rotating. The focal length of the laser 3 is adjusted in accordance with the continuous rotation of the case body 110 as the joining device 2 moves.

[0125] As shown in Figure 26, laser welding is started from a position P1 offset in the first direction (X direction) from the boundary between the outer peripheral surface 116 and the first coating portion 127. The laser passes through a welding path 116a that is inclined at 45° or more with respect to the first end face 117 when viewed from a direction intersecting the first direction (X direction). Subsequently, the laser is continuously irradiated from the welding path 116a to the boundary between the outer peripheral surface 116 and the first coating portion 127. The entire circumference of the case 100 in the first direction (X direction) is welded by passing through the welding path 116b located at the boundary between the outer peripheral surface 116 and the first coating portion 127. After welding until the welding path 116b partially overlaps, the laser is moved through the welding path 116c to a position P2 offset in the first direction (X direction) from the welding path 116b, and the laser irradiation is stopped. By performing laser welding in this order, the welding path 116b along the first end face 117 does not include the start and end points of the welding, thus enabling stable heat input during the joining of the case body 110 and the first sealing plate 120.

[0126] In this embodiment, position P1 is shifted toward the case body 110 in the first direction (X direction) from the boundary between the outer peripheral surface 116 and the first covering portion 127, but it may also be shifted toward the first sealing plate 120. Furthermore, although the joining path in this embodiment is illustrated as a case where the start and end points of welding are not included in the boundary between the outer peripheral surface 116 and the first covering portion 127, the configuration is not limited to this. The joining path may also be configured such that at least one of the start and end points of welding is at the boundary between the outer peripheral surface 116 and the first covering portion 127.

[0127] Next, a modified example of the joining process by laser welding will be described. Figures 27 to 29 are bottom views showing the first to third welding paths when joining the case body and the first sealing plate according to the modified example. Figures 27 to 29 illustrate the state in which the first joint portion 140 is formed on the second side portion 112.

[0128] In the modified example, the first joint 140 is welded by irradiating it with a laser in eight separate passes. Specifically, each of the four planar portions of the outer peripheral surface 116, consisting of a pair of first side portions 111 and a pair of second side portions 112, and the four corner portions between them, are individually laser-welded. Note that irradiating with a laser in multiple passes means that the laser is scanned multiple times, and does not mean that the pulses of the laser are applied one by one.

[0129] As shown in Figure 27, a portion of the first joint 140 is formed by the first welding path 116d. The first welding path 116d is a path in which, with the rotation of the case body 110 stopped, the laser is scanned along the boundary between the outer peripheral surface 116 and the first covering portion 127, and then the laser irradiation is stopped at a position shifted in the first direction (X direction).

[0130] Next, as shown in Figure 28, after the case body 110 is rotated and stopped, a part of the first joint 140 is formed by the second welding path 116e. The second welding path 116e is a path in which, with the rotation of the case body 110 stopped, laser irradiation is started from a position shifted in a first direction (X direction) relative to the boundary between the outer peripheral surface 116 and the first covering portion 127, the laser is scanned along the boundary between the outer peripheral surface 116 and the first covering portion 127, and then laser irradiation is stopped at a position shifted in the first direction (X direction).

[0131] Next, as shown in Figure 29, after rotating and stopping the case body 110, a portion of the first joint 140 is formed by the third welding path 116f. The third welding path 116f is a path that starts laser irradiation from a position shifted in the first direction (X direction) relative to the boundary between the outer peripheral surface 116 and the first covering portion 127, with the rotation of the case body 110 stopped, and scans the laser along the boundary between the outer peripheral surface 116 and the first covering portion 127.

[0132] As described above, laser welding is performed with the case body 110 stopped rotating, then the case body 110 is rotated, and the next laser welding is performed with the case body 110 stopped rotating. These operations are repeated eight times to form the first joint 140. When performing laser welding, the case body 110 is rotated by 45° increments so that, when viewed from the first direction (X direction), the four planar sections or the four corner sections are positioned directly below the joining device. The focal length of the laser welding is changed and adjusted each time the case body 110 is rotated. Alternatively, with the case body 110 stopped rotating, the four planar sections of the pair of first side sections 111 and the pair of second side sections 112 of the outer peripheral surface 116 can be laser-welded, and each of the four corner sections can be laser-welded while the case body 110 is rotating.

[0133] Similar to the welding path described above in this embodiment, the start and end points of the laser welding divided into multiple passes in this modified example are offset from the first direction (X direction). The joining paths of the laser welding divided into multiple passes partially overlap in the direction along the first end face 117. In this modified example, for example, parts of the first welding path 116d and the second welding path 116e overlap, and parts of the second welding path 116e and the third welding path 116f overlap.

[0134] In this way, the first sealing plate 120 and the outer peripheral surface portion 116 of the case body 110 are joined by multiple joints by irradiating them with energy rays (lasers) in multiple stages. Since adjacent joints are formed so that parts of each of them overlap, the entire circumference of the case 100 in the first direction (X direction) is reliably joined.

[0135] After the above-described process, the electrolyte is injected into the case 100 through the injection hole, and the secondary battery 1 is completed.

[0136] The following describes a secondary battery according to a second modification of one embodiment. Since the joint structure between the case body and the sealing plate of this modified secondary battery differs from that of secondary battery 1 according to one embodiment of this technology, the same configuration as that of secondary battery 1 according to one embodiment of this technology will not be repeated in the description.

[0137] Figure 30 is a perspective view showing the bonding state between the case body and the first sealing plate of a secondary battery according to a second modified example of one embodiment.

[0138] The secondary battery 1B according to this modified example comprises a case 100B. The case 100B includes a case body 110B and a first sealing plate 120B.

[0139] The case body 110B has an inner circumferential surface portion 119B. The inner circumferential surface portion 119B extends around an axis in a first direction (X direction).

[0140] The first sealing plate 120B has a first covering portion 127B and a first portion 128B. The first covering portion 127B covers the first side end of the case body 110B from a first direction (X direction). The first portion 128B enters the interior of the case body 110B from the first opening 113 and faces the inner circumferential surface portion 119B of the case body 110B. The first joint portion 140B is formed to span the first sealing plate 120B and the outer circumferential surface portion 116B.

[0141] The first joint 140B is a welded joint formed by laser welding. In the process of sealing the first opening 113B, the first sealing plate 120B and the first end face 117 of the case body 110B are welded together by irradiating a laser from the outer circumference side (DR1 direction in Figure 30) around the axis in the first direction (X direction).

[0142] Since the first part 128B is positioned to fit onto the inner circumferential surface portion 119B of the case body 110B, the position of the first sealing plate 120B relative to the case body 110B becomes more stable. As a result, laser welding can be performed stably.

[0143] The first sealing plate 120B is provided with a protrusion 129B on its outer surface. The protrusion 129B is provided adjacent to the first covering portion 127B. This makes it possible to suppress excessive melting of the area around the first covering portion 127B of the first sealing plate 120B during laser welding, which can cause welding sagging on the outer surface.

[0144] Although Figure 30 shows the configuration of the negative electrode side, the positive electrode side can have the same structure as the negative electrode side. The second sealing plate can also have the same configuration as the first sealing plate 120B. Specifically, the second sealing plate has a second portion, which is not shown. The second portion extends into the case body from the second opening and faces the inner circumferential surface portion 119B of the case body. The second joint is a welded portion formed by laser welding. The second sealing plate and the outer circumferential surface portion 116B of the case body 110B are welded together.

[0145] When the first joint 140B and the second joint are formed by laser welding, even if the laser enters the inner circumferential surface portion 119B of the case body 110B from the outer circumferential side (DR1 direction in Figure 30) around the axis in the first direction (X direction), the laser can be received by the first portion 128B, thus suppressing laser leakage during laser welding.

[0146] In one embodiment of this technology, a secondary battery 1 and its manufacturing method are provided, and the first sealing plate 120 is positioned so as to abut against the first end face 117 of the case body 110, thereby joining the case body 110 and the first sealing plate 120. Compared to the case in which the first sealing plate is inserted into the inner circumference of the case body to join the case body and the sealing plate, the first sealing plate 120 can be stably positioned relative to the case body 110 in the first direction (X direction), and the joining state of the joint can be stabilized. This improves the reliability of the first joint 140 that joins the case body 110 and the first sealing plate 120. The reliability of the second joint 141 can also be improved by adopting a similar configuration on the second sealing plate 130 side as on the first sealing plate 120 side.

[0147] In one embodiment of this technology, the secondary battery 1 is joined by a joint portion 115 extending in a first direction (X direction), which allows a single metal plate to be bent and the bent ends to be joined together, thus enabling efficient manufacturing of the case body 110. Furthermore, by arranging the joint portion 115, the first joint portion 140, and the second joint portion 141 on the outer circumference of the case body 110, the joint portion 115 can be formed from the outer circumference of the case body 110 using a single joining device, thus enabling efficient joining of the case 100.

[0148] In a secondary battery 1 according to one embodiment of this technology, the energy density of the electrode body 200 can be improved by providing a negative electrode tab group 220 (first electrode tab group) and a positive electrode tab group 250 (second electrode tab group) of the electrode body 200, thereby enabling the construction of a secondary battery with excellent output characteristics.

[0149] In one embodiment of this technology, a secondary battery 1 is provided with a negative electrode terminal 301 (first electrode terminal) and a positive electrode terminal 302 (second electrode terminal) on the first sealing plate 120 and the second sealing plate 130, respectively. This allows the secondary battery to be made lower in height when it is placed on a part of the peripheral surface of the case body 110 as the bottom surface.

[0150] In one embodiment of this technology, the secondary battery 1 can be configured so that the electrode body 200 is not too close to the first sealing plate 120 and the second sealing plate 130 by the first spacer 600 and the second spacer. As a result, the electrode body 200 is not positioned directly below the joint between the sealing plates 120, 130 and the case body 110, so that even if a laser enters the inside of the case 100 from between the sealing plates 120, 130 and the case body 110, damage to the electrode body 200 can be suppressed.

[0151] In a modified version of the secondary battery 1 according to one embodiment of this technology, by providing the sealing plate with portions (first portion 128B and second portion) that face the inner circumferential surface portion 119B of the case body 110B, even if the laser used during welding between the sealing plate and the case body 110B passes from the welding position to the inner circumferential surface portion 119B side of the case body 110B, the first portion 128B and the second portion of the sealing plate can receive the laser, thereby preventing laser leakage during welding.

[0152] In the manufacturing method of the secondary battery 1 according to one embodiment of this technology, the joint portion 115, the first joint portion 140, and the second joint portion 141 can each be formed from the outer circumference in the axial direction of the first direction (X direction), so the case 100 can be manufactured efficiently.

[0153] In a method for manufacturing a secondary battery 1 according to one embodiment of this technology, the laser used to join the case body 110 and the sealing plates 120 and 130 is applied in multiple passes, thereby dispersing the heat input to the case body 110 and reducing the thermal impact on the case body 110. Furthermore, by applying the laser in multiple passes, the laser stroke can be shortened, allowing for a smaller joining device.

[0154] In a method for manufacturing a secondary battery 1 according to one embodiment of this technology, the laser is irradiated in multiple stages, and both the first end and the second end of the joint 115 are designated as the starting or ending point for welding. This makes it possible to stably form the joint 115 by unifying the joining state of the first end and the second end, compared to a case where the joint 115 is formed by a single welding process and the joining state of the first end and the second end of the joint 115 is not unified at the starting or ending point of welding.

[0155] In the method for manufacturing a secondary battery 1 according to one embodiment of this technology, the first joint portion 140 and the second joint portion 141 can be formed while the case body 110 is rotated. Compared to a configuration in which the case body 110 is stationary and the joining device moves around the case body 110, the joining device 2 can be made smaller and the secondary battery 1 can be manufactured efficiently.

[0156] In a method for manufacturing a secondary battery 1 according to one embodiment of this technology, the case body 110 is gripped by the manufacturing apparatus to the extent that the electrode body 200 can be held between the case body 110. This prevents the electrode body 200 from moving inside the case body 110 when the case body 110 is rotated to perform bonding, thereby suppressing damage to the electrode body 200.

[0157] In a method for manufacturing a secondary battery 1 according to one embodiment of this technology, by performing a temporary joining of the case body 110 and the sealing plates 120 and 130 before joining them, it is possible to suppress misalignment between the case body 110 and the sealing plates 120 and 130 when the case body 110 is rotated to perform the joining.

[0158] In a method for manufacturing a secondary battery 1 according to one embodiment of this technology, the secondary battery 1 can be efficiently manufactured by simultaneously forming the first joint portion 140 and the second joint portion 141.

[0159] 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]

[0160] 1,1B,9 Secondary battery, 2 Bonding device, 100,100B,900 Case, 110,110B,910 Case body, 111 First side section, 112 Second side section, 113,113B,913 First opening, 114 Second opening, 115,115A Joint section, 115a,115b,115c,115d,116a,116b,116c,116d Welding path, 116,116B Outer surface section, 116d First welding path, 116e Second welding path, 116f Third welding path, 117,917 First end face, 118 Second end face, 119B,919 Inner surface section, 120,120B,920 First sealing plate (sealing plate), 124,134 Injection hole, 125, 135 Gas discharge valve, 127, 127B First covering part, 128B First part, 129B Protrusion, 130 Second sealing plate (sealing plate), 137 Second covering part, 140, 140B, 940 First joint, 141 Second joint, 200, 201, 202 Electrode body, 210 Negative electrode plate, 210S Negative electrode base plate, 211 Negative electrode core body, 212 Negative electrode active material layer, 220 Negative electrode tab group, 230 Negative electrode tab, 240 Positive electrode plate, 240S Positive electrode base plate, 241 Positive electrode core body, 242 Positive electrode active material layer, 243 Positive electrode protective layer, 250 Positive electrode tab group, 260 Positive electrode tab, 300 Electrode terminal, 301 Negative electrode terminal, 302 Positive terminal, 400 current collector, 410 negative current collector, 420 positive current collector, 430 first conductive member, 431 first planar section, 432 second planar section, 433, 434, 441, 454 joint section, 435 stepped section, 440 second conductive member, 510 first insulating member, 520 second insulating member, 600 first spacer, 610 first component, 620 second component, 630a, 630b engagement section, 700 insulating sheet, P1, P2 position, R1 first region, R2 second region.

Claims

1. An electrode body comprising a first electrode and a second electrode having a polarity different from that of the first electrode, The system comprises a case for housing the electrode body, The aforementioned case is, A case body having a first opening located at the end of the first side in the first direction, and a second opening located at the end of the second side opposite to the first side in the first direction, A first sealing plate that seals the first opening, The second opening is sealed by a second sealing plate, The case body has an outer peripheral surface portion extending around the axis in the first direction, a first end surface located at the end of the first side and extending in a direction intersecting the first direction, and a second end surface located at the end of the second side and extending in a direction intersecting the first direction. The first sealing plate is fitted with a first electrode terminal that is electrically connected to the first electrode. In the short-side direction of the first sealing plate, the first electrode terminals are off-center to one side from the center of the first sealing plate. The first sealing plate has a first covering portion that covers at least a part of the first end face from the first direction, The second sealing plate has a second covering portion that covers at least a part of the second end face from the first direction, A first joint is formed so as to span the outer peripheral surface portion and the first covering portion. A secondary battery in which a second joint portion is formed so as to span the outer peripheral surface portion and the second covering portion.

2. The secondary battery according to claim 1, wherein the case body has a joint portion extending in the first direction on the outer peripheral surface.

3. The electrode body is The main body and A group of first electrode tabs electrically connected to the first electrode and located on the first side with respect to the main body, A secondary battery according to claim 1 or claim 2, comprising a group of second electrode tabs electrically connected to the second electrode and located on the second side with respect to the main body.

4. The secondary battery according to claim 1 or claim 2, comprising a second electrode terminal electrically connected to the second electrode and attached to the second sealing plate.

5. A first spacer located between the electrode body and the first sealing plate, A secondary battery according to claim 1 or claim 2, comprising a second spacer located between the electrode body and the second sealing plate.

6. The case body has an inner circumferential surface portion that extends around an axis in the first direction, The first sealing plate extends further into the case body than the first opening and has a first portion that faces the inner circumferential surface of the case body. The second sealing plate extends further into the case body than the second opening and has a second portion that faces the inner circumferential surface of the case body. The secondary battery according to claim 1 or claim 2, wherein the first joint and the second joint are welded joints.

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