Secondary battery and method of manufacturing same

Abstract

To improve reliability of a joining portion that joins a case main body and a sealing plate.SOLUTION: A case main body 110 has an outer peripheral surface portion 116, a first end surface 117, and a second end surface 118. The outer peripheral surface portion 116 extends around an axis in a first direction. The first end surface 117 is located at the end portion of a first side and extends in a direction intersecting the first direction. The second end surface 118 is located at the end portion of a second side and extends in the direction intersecting the first direction. A first sealing plate 120 has a first covering portion 127 that covers at least a portion of the first end surface 117 from the first direction. A second sealing plate 130 has a second covering portion 137 that covers at least a portion of the second end surface 118 from the first direction. A first joining portion 140 is formed to bridge the outer peripheral surface portion 116 and the first covering portion 127, and a second joining portion 141 is formed to bridge the outer peripheral surface portion 116 and the second covering portion 137.SELECTED DRAWING: Figure 17

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) is a prior art document that discloses the configuration of a secondary battery. The secondary battery described in Patent Document 1 includes an electrode body, a case, and a cap plate. The electrode body is built into the case. The case has openings at both ends for inserting the electrode group. The cap plate is coupled to the openings. The cap plate is disposed inside the case to seal the opening. [Prior art documents] [Patent documents]

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

[0004] In the secondary battery described in Patent Document 1, the sealing plate cannot be positioned relative to the case body, and the joint between the case body and the sealing plate may not be formed stably. Therefore, there is room for improving the reliability of the joint.

[0005] The present technology has been made to solve the above-mentioned problems, and aims to provide a secondary battery and a manufacturing method thereof that can improve the reliability of the joint that joins the case body and the sealing plate. [Means for solving the problem]

[0006] The present technology provides the following secondary battery. [1] An electrode assembly including a first electrode and a second electrode having a polarity different from that of the first electrode; A case for accommodating the electrode body, The case is a case body having a first opening located at an end of a first side in a first direction and a second opening located at an end of a second side opposite to the first side in the first direction; a first sealing plate that seals the first opening; a second sealing plate that seals the second opening, the case body has an outer circumferential surface portion extending around an axis in the first direction, a first end face located at an end of the first side and extending in a direction intersecting the first direction, and a second end face located at an end of the second side and extending in a direction intersecting the first direction, the first sealing plate has a first covering portion covering at least a portion of the first end face from the first direction, the second sealing plate has a second covering portion covering at least a portion of the second end face from the first direction, A first bonding portion is formed so as to span the outer circumferential surface portion and the first covering portion, A secondary battery, comprising: a second bonding portion formed across the outer circumferential surface portion and the second covering portion. [2] The secondary battery according to [1], wherein the case body has a joint portion extending in the first direction on the outer circumferential surface portion. [3] The electrode body is A main body portion, a first electrode tab group electrically connected to the first electrodes and located on the first side with respect to the main body portion; A secondary battery as described in [1] or [2], further comprising: a second electrode tab group electrically connected to the second electrodes and located on the second side relative to the main body portion. [4] a first electrode terminal electrically connected to the first electrode and attached to the first sealing plate; The secondary battery according to any one of [1] to [3], further comprising: a second electrode terminal electrically connected to the second electrode and attached to the second sealing plate. [5] a first spacer between the electrode body and the first sealing plate; The secondary battery according to any one of [1] to [4], further comprising: a second spacer between the electrode body and the second sealing plate. [6] The case body has an inner circumferential surface portion extending around an axis in the first direction, the first sealing plate has a first portion that is inwardly protruding from the first opening into the case body and faces the inner circumferential surface of the case body, the second sealing plate has a second portion that is indented inside the case body through the second opening and faces the inner circumferential surface of the case body, The secondary battery according to any one of [1] to [5], wherein the first joint and the second joint are welded joints.

[0007] The present technology provides the following method for producing a secondary battery. [7] preparing a case body having a first opening located at an end of a first side in a first direction, a second opening located at an end of a second side opposite the first side in the first direction, an outer circumferential surface portion extending around an 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 a second end face located at the end of the second side and extending in a direction intersecting the first direction; inserting an electrode body including a first electrode and a second electrode having a polarity different from that of the first electrode into the case body; a step of contacting a first sealing plate with the first end surface so as to cover at least a portion of the first end surface from the first direction, and performing a joining process from an outer periphery side around an axis in the first direction to form a joint portion spanning the first sealing plate and the outer periphery surface portion of the case body, thereby sealing the first opening; abutting a second sealing plate against the second end surface so as to cover at least a portion of the second end surface from the first direction, and performing a joining process from an outer circumferential side around an axis in the first direction to form a joint spanning the second sealing plate and the outer circumferential surface of the case body, thereby sealing the second opening. [8] The method for manufacturing a secondary battery described in [7], wherein the case body is formed by bending a plate-like member into a cylindrical shape and joining both ends of the plate-like member bent into a cylindrical shape to each other. [9] The method for manufacturing a secondary battery according to [8], wherein joining the two ends of the plate-like members to each other includes welding by irradiating the two ends with energy rays in multiple steps.

[10] The joining of the two ends of the plate-like member to each other includes welding by irradiating the two ends with an energy beam in a plurality of separate steps; The welding by irradiating the energy beam in a plurality of times is welding a first region including an end portion of the first side of the case body; and welding a second region including an end portion of the second side of the case body, In the welding of the first region and the second region, the end of the first side and the end of the second side become a start point or an end point of welding, When the end of the first side is a welding start point, the end of the second side is a welding start point, The method for manufacturing a secondary battery according to [8], wherein when the end portion on the first side is an end point of welding, the end portion on the second side is an end point of welding.

[11] The method for manufacturing a secondary battery according to any one of [7] to

[10] , wherein in the step of sealing the first opening, forming the joint includes welding by irradiating an energy ray multiple times.

[12] by irradiating the energy beam a plurality of times and welding the first sealing plate and the case body at a plurality of the joints, The method for manufacturing a secondary battery according to

[11] , wherein adjacent ones of the plurality of joints are formed so that parts of the adjacent joints overlap with each other.

[13] The method for manufacturing a secondary battery described in any one of [7] to

[12] , wherein at least one of the steps of sealing the first opening and sealing the second opening includes a step of rotating the case body around an axis in the first direction.

[14]

[13] . The method for manufacturing a secondary battery described in

[13] , wherein at least one of the steps of sealing the first opening and sealing the second opening includes pressing the case body until it is deformed and sandwiching the electrode body by the case body.

[15] a step of temporarily joining the first sealing plate and the case body before the step of sealing the first opening; The method for manufacturing a secondary battery according to

[13] or

[14] , further comprising a step of temporarily joining the second sealing plate and the case body before the step of sealing the second opening.

[16] The method for producing a secondary battery according to any one of [7] to

[15] , wherein at least a part of the step of sealing the first opening and the step of sealing the second opening are performed simultaneously.

[17] The case body has an inner circumferential surface portion extending around an axis in the first direction, the first sealing plate has a first portion that is inwardly protruding from the first opening into the case body and faces the inner circumferential surface of the case body, the second sealing plate has a second portion that is indented inside the case body through the second opening and faces the inner circumferential surface of the case body, The method for manufacturing a secondary battery according to any one of [7] to

[16] , wherein in the step of sealing the first opening and the step of sealing the second opening, the first sealing plate and the case body are welded together, and the second sealing plate and the case body are welded together, by irradiating an energy ray from an outer circumferential side around an axis in the first direction. Effect of the Invention

[0008] According to the present technology, it is possible to improve the reliability of the joint that joins the case body and the sealing plate. [Brief description of the drawings]

[0009] [Figure 1] 1 is a front view showing a configuration of a secondary battery according to an embodiment of the present technology; [Diagram 2] 2 is a diagram showing the secondary battery shown in FIG. 1 as viewed from the direction of arrow II. [Diagram 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. [Diagram 5] 2 is a front cross-sectional view of the secondary battery shown in FIG. [Figure 6] FIG. 2 is a front view showing a negative electrode original plate before the negative electrode plate is formed. [Figure 7] 7 is a cross-sectional view taken along the line VII-VII of the negative electrode original plate shown in FIG. 6. [Figure 8] FIG. 2 is a front view showing a negative electrode plate formed from the negative electrode original plate. [Figure 9] FIG. 2 is a front view showing a positive electrode original plate before the positive electrode plate is formed. [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 positive electrode plate formed from a positive electrode original plate. [Figure 12] FIG. 2 is a diagram showing an electrode assembly and a current collector taken out from a secondary battery. [Figure 13] FIG. 4 is a front view of a connection structure between a negative electrode tab group and a negative electrode current collector. [Figure 14] FIG. 4 is a cross-sectional view of a connection structure between a negative electrode tab group and a negative electrode current collector. [Figure 15] 11A to 11C are diagrams showing a process of inserting the electrode body into the case body. [Figure 16]11A and 11B are diagrams showing a step of arranging a spacer between the sealing plate and the electrode body. [Figure 17] 4 is a cross-sectional view showing a joint portion of a case included in the secondary battery according to the embodiment; FIG. [Figure 18] 10 is a perspective view showing a joined state between a case body and a first sealing plate included in a secondary battery according to a comparative example. FIG. [Figure 19] 4 is a flowchart showing a method for manufacturing a secondary battery according to an embodiment. [Figure 20] 11 is a bottom view showing a joining method when molding the case body. FIG. [Figure 21] FIG. 11 is a bottom view showing a joining method when molding a case body according to a first modified example of the embodiment. [Figure 22] 1 is a perspective view showing a method of joining a case body and a first sealing plate included in a secondary battery according to one embodiment. FIG. [Figure 23] 11 is a side view showing the state immediately after starting to join the case body and the first sealing plate. FIG. [Figure 24] 13 is a side view showing a state in which the short side portions of the case body and the first sealing plate are joined while being rotated. FIG. [Diagram 25] 13 is a side view showing a state in which the long side portions of the case body and the first sealing plate are joined while being rotated. FIG. [Figure 26] 11 is a bottom view showing a joining path when joining the case body and the first sealing plate. FIG. [Figure 27] 13 is a bottom view showing a first welding path when joining a case body and a first sealing plate according to a modified example. FIG. [Figure 28] 13 is a bottom view showing a second welding path when joining the case body and the first sealing plate according to the modified example. FIG. [Figure 29] 13 is a bottom view showing a third welding path when joining the case body and the first sealing plate according to the modified example. FIG. [Diagram 30] 13 is a perspective view showing a joined state between a case body and a first sealing plate included in a secondary battery according to a second modified example of the embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] 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 will not be repeated.

[0011] In the embodiments described below, when referring to the number, amount, etc., the scope of the present technology is not necessarily limited to the number, amount, etc., unless otherwise specified. In addition, in the following embodiments, each component is not necessarily essential to the present technology, unless otherwise specified. In addition, the present technology is not necessarily limited to those that achieve all of the effects and advantages mentioned in the present embodiment.

[0012] In this specification, the words "comprise", "include" and "have" are open-ended, i.e., when a certain configuration is included, other configurations may or may not be included.

[0013] Furthermore, when geometric terms and terms expressing positional and directional relationships, such as "parallel," "orthogonal," "45° diagonal," "coaxial," and "along" are used in this specification, these terms allow for manufacturing errors and slight variations. When terms expressing relative positional relationships, such as "upper side" and "lower side," are used in this specification, these terms are used to indicate relative positional relationships in one state, and the relative positional relationships can be inverted or rotated to any angle depending on the installation direction of each mechanism (for example, by turning the entire mechanism upside down).

[0014] In this specification, the term "secondary battery" is not limited to lithium ion batteries, but may include other secondary batteries such as nickel-metal hydride batteries and sodium ion batteries. In this specification, the term "electrode" may collectively refer to a positive electrode and a negative electrode.

[0015] In the drawings, the direction along the winding axis of the electrode body of the secondary battery is the X direction as a first direction, the Y direction is the short side direction of the electrode body that is perpendicular to the first direction and seen from the first direction as a second direction, and the Z direction is the long side direction of the electrode body that is perpendicular to the first direction and seen from the first direction as a third direction. In addition, in order to make the invention easier to understand, the dimensions of each component in the drawings are sometimes shown differently from the actual dimensions.

[0016] In this specification, the first direction (X direction) may be referred to as the "width direction" of the secondary battery or the case body, the second direction (Y direction) may be referred to as the "thickness direction" of the secondary battery or the case body, and the third direction (Z direction) may be referred to as the "height direction" of the secondary battery or the case body.

[0017] (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.

[0018] 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 on a vehicle.

[0019] 1 to 5, the secondary battery 1 includes a case 100, an electrode assembly 200, an electrode terminal 300, and a current collector 400. The case 100 includes a case body 110, a first sealing plate 120, and a second sealing plate .

[0020] When configuring an assembled battery 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 direction) by a restraining member to form a battery module, or the assembled battery may be directly supported on the side surface of a battery pack case without using a restraining member.

[0021] 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.

[0022] As shown in Fig. 1 and Fig. 2, a first sealing plate 120 and a second sealing plate 130 are provided at both ends of the case body. The case body 110 can be formed into a square tube shape, for example, by abutting the edges of bent plate-like members (joint 115 shown in Fig. 2) and joining them together (for example, by laser welding). The corners of the "square tube" may have an R shape. The joint 115 in this embodiment extends in a first direction (X direction) on the outer circumferential surface of the case body 110.

[0023] 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 allows a relatively large (high capacity) secondary battery 1 to be configured. The dimension (height) of the case body 110 in the Z direction is preferably about 20 cm or less, more preferably about 15 cm or less, and even more preferably about 10 cm or less. This allows a relatively low height (low height) secondary battery 1 to be configured, improving the mountability in a vehicle, for example.

[0024] The case body 110 includes a pair of first side surface portions 111 and a pair of second side surface portions 112. The pair of first side surface portions 111 constitute a part of the side surface of the case 100. The pair of second side surface portions 112 constitute the bottom surface portion and the top surface portion of the case 100. The pair of first side surface portions 111 and the pair of second side surface portions 112 are provided so as to intersect with each other. The pair of first side surface portions 111 and the pair of second side surface portions 112 are connected at their respective ends. It is desirable that each of the pair of first side surface portions 111 has an area larger than each of the pair of second side surface portions 112.

[0025] 3, a first opening 113 is provided at an end of a first side in a first direction (X direction) of case body 110. First opening 113 is sealed by a first sealing plate 120. First opening 113 and first sealing plate 120 have a substantially rectangular shape with a short side direction in the Y direction and a long side direction in the Z direction.

[0026] A negative electrode terminal 301 (first electrode terminal), a liquid injection hole 124, and a gas exhaust valve 125 are provided on the first sealing plate 120. The positions of the negative electrode terminal 301, the liquid injection hole 124, and the gas exhaust valve 125 can be changed as appropriate.

[0027] 4, a second opening 114 is provided at an end of a second side opposite to the first side in the first direction (X direction) of case body 110. Second opening 114 is sealed by a second sealing plate 130. Second opening 114 and second sealing plate 130 have a substantially rectangular shape with a short side direction in the Y direction and a long side direction in the Z direction.

[0028] A positive electrode terminal 302 (second electrode terminal), a liquid injection hole 134, and a gas exhaust valve 135 are provided on the second sealing plate 130. The positions of the positive electrode terminal 302, the liquid injection hole 134, and the gas exhaust valve 135 can be changed as appropriate.

[0029] 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, an aluminum alloy, iron, an iron alloy, or the like.

[0030] In the present embodiment, the thickness of each of first sealing plate 120 and second sealing plate 130 is greater than the thickness (plate thickness) of case body 110. This makes it possible to mitigate the thermal influence when forming first bonding portion 140 and second bonding portion 141 (described later) in first sealing plate 120 and second sealing plate 130, which occupy a smaller volume than case body 110, and to suppress the formation of holes during bonding.

[0031] 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, that is, the case 100.

[0032] The positive electrode terminal 302 is electrically connected to the positive electrode of the electrode body 200. The positive electrode terminal 302 is attached to the second sealing plate 130, i.e., the case 100.

[0033] The negative terminal 301 is made of a conductive material (more specifically, a metal), and may be made of, for example, copper or a copper alloy. The outer surface of the negative terminal 301 may be provided with a portion or layer made of aluminum or an aluminum alloy.

[0034] The positive terminal 302 is made of a conductive material (more specifically, a metal), and may be made of, for example, aluminum or an aluminum alloy.

[0035] The liquid inlet holes 124 and 134 are sealed by a sealing member (not shown) which may be, for example, a blind rivet or other metal member.

[0036] The gas exhaust valves 125, 135 break when the pressure inside the case 100 reaches or exceeds a predetermined value, and exhaust the gas inside the case 100 to the outside.

[0037] 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 band-shaped positive electrode plate and a band-shaped negative electrode plate are both wound via a band-shaped separator (not shown). However, in this specification, the "electrode body" is not limited to a wound-type electrode body, and may be a laminated electrode body in which a plurality of positive electrode plates and a plurality of negative electrode plates are alternately laminated. The band-shaped separator may be composed of, for example, a polyolefin microporous film. The electrode body may include a plurality of positive electrode plates and a plurality of negative electrode plates, and the positive electrode tabs provided on each positive electrode plate may be laminated to form a positive electrode tab group, or the negative electrode tabs provided on each negative electrode plate may be laminated to form a negative electrode tab group.

[0038] 5, case 100 houses electrode assembly 200. Electrode assembly 200 is housed in case 100 so that its winding axis is parallel to the X direction.

[0039] Specifically, one or more wound electrode bodies are housed together with an electrolytic solution (electrolyte) (not shown) inside an insulating sheet 700 (described later) arranged in the case 100. As the electrolytic solution (non-aqueous electrolytic solution), for example, LiPF6 dissolved at a concentration of 1.2 mol / L in a non-aqueous solvent in which ethylene carbonate (EC), ethyl methyl carbonate (EMC), and diethyl carbonate (DEC) are mixed in a volume ratio (25°C) of 30:30:40 can be used. Note that a solid electrolyte may be used instead of the electrolytic solution.

[0040] The electrode body 200 includes a main body portion (a portion in which positive electrode plates and negative electrode plates are stacked with a separator therebetween), a negative electrode tab group 220 (first electrode tab group), and a positive electrode tab group 250 (second electrode tab group).

[0041] 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 an end of a first side of the electrode body 200 in a first direction (X direction) with respect to the main body. The first side in this embodiment is the first sealing plate 120 side. The positive electrode tab group 250 is located at an end of a second side in the first direction (X direction) with respect to the main body. The second side in this embodiment is the second sealing plate 130 side.

[0042] The negative electrode tab group 220 and the positive electrode tab group 250 are formed so as to protrude from the center portion of the electrode body 200 toward the first sealing plate 120 or the second sealing plate 130, respectively.

[0043] 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 a plate-shaped member. The electrode body 200 is electrically connected to the negative electrode terminal 301 and the positive electrode terminal 302 via the current collector 400.

[0044] The negative electrode current collector 410 is disposed 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), and may be made of, for example, copper or a copper alloy.

[0045] The positive electrode current collector 420 is disposed 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), and may be made of, for example, 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 play the role of the positive electrode terminal 302.

[0046] (Configuration of electrode body 200) FIG. 6 is a front view showing the negative electrode original plate 210S before the negative electrode plate 210 (first electrode) is formed, FIG. 7 is a cross-sectional view taken along line VII-VII of the negative electrode original plate 210S shown in FIG. 6, and FIG. 8 is a front view showing the negative electrode plate 210 formed from the negative electrode original plate 210S.

[0047] The negative electrode plate 210 is manufactured by processing a negative electrode original plate 210S. As shown in Figures 6 and 7, the negative electrode original plate 210S includes a negative electrode core 211 and a negative electrode active material layer 212. The negative electrode core 211 is a copper foil or a copper alloy foil.

[0048] A negative electrode active material layer 212 is formed on both sides of the negative electrode core 211 except for one end portion. The negative electrode active material layer 212 is formed by applying a negative electrode active material layer slurry with a die coater.

[0049] 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.

[0050] The negative electrode core 211 coated with the negative electrode active material layer slurry is dried to remove water contained in the negative electrode active material layer slurry, thereby forming the negative electrode active material layer 212. Furthermore, the negative electrode active material layer 212 is compressed to form a negative electrode original plate 210S including the negative electrode core 211 and the negative electrode active material layer 212. The negative electrode original plate 210S is cut into a predetermined shape to form the negative electrode plate 210. The negative electrode original plate 210S can be cut by laser processing using energy beam irradiation, die processing, cutter processing, or the like.

[0051] As shown in FIG. 8, a plurality of negative electrode tabs 230 made of a negative electrode core 211 are provided at one end in the width direction of a negative electrode plate 210 formed from a negative electrode original plate 210S. When the negative electrode plate 210 is wound, the plurality of negative electrode tabs 230 are stacked to form a negative electrode tab group 220. As a result, the negative electrode tab group 220 is connected to the negative electrode plate 210 (first electrode). The position and length in the protruding direction of each of the plurality of negative electrode tabs 230 are appropriately adjusted in consideration of the state in which the negative electrode tab group 220 is connected to the negative electrode current collector 410. The shape of the negative electrode tab 230 is not limited to the one exemplified in FIG. 8.

[0052] FIG. 9 is a front view showing the positive electrode original plate 240S before the positive electrode plate 240 (second electrode) is formed, FIG. 10 is a cross-sectional view taken along line XX of the positive electrode original plate 240S shown in FIG. 9, and FIG. 11 is a front view showing the positive electrode plate 240 formed from the positive electrode original plate 240S.

[0053] The positive electrode plate 240, which is the second electrode, has a polarity different from that of the negative electrode plate 210, which is the first electrode. The positive electrode plate 240 is manufactured by processing a positive electrode original plate 240S. As shown in Fig. 9 and Fig. 10, the positive electrode original plate 240S includes a positive electrode core body 241, a positive electrode active material layer 242, and a positive electrode protective layer 243. The positive electrode core body 241 is an aluminum foil or an aluminum alloy foil.

[0054] A positive electrode active material layer 242 is formed on both sides of the positive electrode core 241 except for one end portion. The positive electrode active material layer 242 is formed on the positive electrode core 241 by applying a positive electrode active material layer slurry with a die coater.

[0055] 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.

[0056] The positive electrode protective layer 243 is in contact with the positive electrode core 241 and is formed at one end in the width direction of the positive electrode active material layer 242. 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 a larger electric resistance than the positive electrode active material layer 242.

[0057] 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.

[0058] The positive electrode core 241 coated with the positive electrode active material layer slurry and the positive electrode protective layer slurry is dried, and the NMP contained in the positive electrode active material layer slurry and the positive electrode protective layer slurry is removed to form the positive electrode active material layer 242 and the positive electrode protective layer 243. Furthermore, the positive electrode active material layer 242 is compressed to form a positive electrode original plate 240S including the positive electrode core 241, the positive electrode active material layer 242, and the positive electrode protective layer 243. The positive electrode original plate 240S is cut into a predetermined shape to form the positive electrode plate 240. The positive electrode original plate 240S can be cut by laser processing using energy beam irradiation, die processing, cutter processing, or the like.

[0059] As shown in FIG. 11, a plurality of positive electrode tabs 260 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 original plate 240S. When the positive electrode plate 240 is wound, the plurality of positive electrode tabs 260 are stacked to form a positive electrode tab group 250. As a result, the positive electrode tab group 250 is connected to the positive electrode plate 240 (second electrode). The position and length in the protruding direction of each of the plurality of positive electrode tabs 260 are appropriately adjusted in consideration of the state in which the positive electrode tab group 250 is connected to the positive electrode current collector 420. The shape of the positive electrode tab 260 is not limited to the one exemplified in FIG. 11.

[0060] A positive electrode protection layer 243 is provided at the base of each of the positive electrode tabs 260. The positive electrode protection layer 243 does not necessarily have to be provided at the base of the positive electrode tab 260.

[0061] In a typical example, the thickness of the negative electrode tab 230 (one piece) is smaller than the thickness of the positive electrode tab 260 (one piece). In this case, the thickness of the negative electrode tab group 220 is smaller than the thickness of the positive electrode tab group 250.

[0062] (Connection structure between electrode body 200 and current collector 400) Fig. 12 is a diagram showing the electrode body 200 and the current collector 400 taken out from the secondary battery 1. As shown in Fig. 12, the electrode body 200 is formed by stacking two electrode bodies 201, 202, each of which is a wound type electrode body. In the example shown in Fig. 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, may be composed of three or more wound type electrode bodies, or may be composed of a laminated type electrode body.

[0063] The negative electrode tab group 220 is joined to the negative electrode current collector 410 at joint points 434 , and the positive electrode tab group 250 is joined to the positive electrode current collector 420 at joint points 454 .

[0064] Fig. 13 is a front view of the connection structure between the negative electrode tab group and the negative electrode current collector, and Fig. 14 is a cross-sectional view of the connection structure between the negative electrode tab group and the negative electrode current collector.

[0065] 13 and 14, the negative electrode current collector 410 electrically connects the negative electrode terminal 301 and the negative electrode tab group 220. The negative electrode current collector 410 in this embodiment is connected to the negative electrode terminal 301 between the electrode body 200 and the first sealing plate 120.

[0066] 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 portion 433. The first conductive member 430 and the second conductive member 440 are joined by, for example, laser welding.

[0067] The first conductive member 430 is joined to the negative electrode tab group 220 at a joint 434. The joint 434 can be formed by, for example, ultrasonic welding, resistance welding, laser welding, crimping, etc. In the present embodiment, the first conductive member 430 and the negative electrode tab group 220 are joined by, for example, ultrasonic bonding.

[0068] Second conductive member 440 is connected to negative terminal 301 at joint 441. Joint 441 may be formed by, for example, ultrasonic welding, resistance welding, laser welding, crimping, or the like. In this embodiment, negative terminal 301 and second conductive member 440 are joined by, for example, providing a through hole in second conductive member 440, inserting negative terminal 301 into the through hole, crimping negative terminal 301 onto second conductive member 440, and then welding the crimped portion to second conductive member 440.

[0069] 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 disposed along the first sealing plate 120.

[0070] A step portion 435 is provided between the first flat portion 431 and the second flat portion 432. The step portion 435 makes the positions of the first flat portion 431 and the second flat portion 432 in the first direction (X direction) different after the secondary battery 1 is assembled. This allows the first flat portion 431 and the second flat portion 432 to be arranged side by side in one direction. The step portion 435 extends along the third direction (Z direction).

[0071] A first insulating member 510 (resin member) is disposed between the negative electrode terminal 301 and the first sealing plate 120. A second insulating member 520 (resin member) is disposed between the first sealing plate 120 and the first conductive member 430 and the second conductive member 440. The first insulating member 510 and the second insulating member 520 may be an integrated part.

[0072] Negative electrode terminal 301 is attached to first sealing plate 120 via first insulating member 510. Negative electrode terminal 301 is provided so as to be exposed to the outside of first sealing plate 120 and to reach second conductive member 440 of negative electrode current collector 410 provided on the inner surface side of first sealing plate 120.

[0073] The procedure for assembling each part 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 electrically connected to the electrode body 200 is attached to the second conductive member 440. At this time, the first conductive member 430 is placed on the first insulating member 510 so that a portion of the first conductive member 430 overlaps with the second conductive member 440. Next, the first conductive member 430 and the second conductive member 440 are connected by welding at a joint 434.

[0074] However, negative electrode terminal 301 may be electrically connected to first sealing plate 120. Also, first sealing plate 120 may play the role of negative electrode terminal 301.

[0075] 13 and 14, the negative electrode current collector 410 is illustrated as being made up of two components (the first conductive member 430 and the second conductive member 440), but the negative electrode current collector 410 may be made up of a single component.

[0076] Although the connection structure on the negative electrode side is shown in FIG. 13 and FIG. 14, the basic connection structure on the positive electrode side is similar to that on the negative electrode side.

[0077] (Step of Inserting the Electrode Body 200) 15 is a diagram showing a process of inserting the electrode body 200 into the case body 110. As shown in FIG.

[0078] The insulating sheet 700 may be made of, for example, 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).

[0079] The insulating sheet 700 does not necessarily have to cover the entire surface of the electrode body 200. The insulating sheet 700 preferably covers an area of ​​about 50% or more, and more preferably about 70% or more, of the outer surface of the electrode body. Of the six faces of the approximately rectangular parallelepiped (flat) electrode body 200, the insulating sheet 700 preferably covers the entire four faces other than the two faces on which the negative electrode tab group 220 and the positive electrode tab group 250 are formed, respectively.

[0080] FIG. 16 is a diagram showing a process of placing a first spacer 600 between the first sealing plate 120 and the electrode body 200. As shown in FIG.

[0081] 16, the negative electrode tab group 220 arranged from the electrode body 200 toward the first sealing plate 120 is curved from the center in the Y direction of the first sealing plate 120 toward the end, and then folded back toward the center. A first spacer 600 is provided to accommodate the curved portion of the negative electrode tab group 220. The first spacer 600 is arranged between the electrode body 200 and the first sealing plate 120.

[0082] The first spacer 600 includes a first component 610 and a second component 620. The first component 610 and the second component 620 are engaged with each other by engaging portions 630a, 630b when the first component 610 and the second component 620 are slid along the Y direction from the end side toward the center side of the first sealing plate 120. As a result, the first spacer 600 is fixed to the first sealing plate 120 via the second insulating member 520, and the positional stability of the first spacer 600 is increased.

[0083] The secondary battery 1 according to this embodiment includes a second spacer (not shown). The second spacer is disposed between the electrode body and the second sealing plate. The second spacer may have a similar structure to the first spacer 600. The first spacer 600 and the second spacer may have different shapes.

[0084] (Joint structure between case body 110 and sealing plates 120, 130) Fig. 17 is a cross-sectional view showing a joint of a case included in a secondary battery according to one embodiment. In Fig. 17, configurations other than case 100 are omitted in order to facilitate understanding of the invention.

[0085] As shown in FIG. 17, the case body 110 has an outer circumferential surface portion 116, a first end surface 117, and a second end surface 118.

[0086] The outer peripheral surface portion 116 extends around an axis in a first direction (X direction). The outer peripheral surface portion 116 also extends along the first direction (X direction). Although the outer peripheral surface portion 116 extends approximately parallel to the first direction (X direction), it may be inclined from the first direction (X direction) due to processing errors during the manufacture of the case body 110. Furthermore, the surface of the outer peripheral surface portion 116 may have irregularities or steps.

[0087] The first end surface 117 is located at an end portion on the first side in the first direction (X direction). The first end surface 117 extends in a direction intersecting the first direction (X direction). In the present embodiment, the first end surface 117 extends in a direction substantially perpendicular to the first direction (X direction). Since the first end surface 117 extends in a direction substantially perpendicular to the first direction (X direction), the first sealing plate 120 is likely to come into contact with the first end surface 117.

[0088] The second end surface 118 is located at an end on the second side in the first direction (X direction). The second end surface 118 extends in a direction intersecting the first direction (X direction). In the present embodiment, the second end surface 118 extends in a direction substantially perpendicular to the first direction (X direction). Since the second end surface 118 extends in a direction substantially perpendicular to the first direction (X direction), the second sealing plate 130 is likely to come into contact with the second end surface 118.

[0089] First sealing plate 120 has first covering portion 127. First covering portion 127 covers at least a portion of first end face 117 from the first direction (X direction). This makes it easy to stably position first sealing plate 120 with respect to case body 110. First covering portion 127 in the present embodiment covers the entire surface of first end face 117 from the first direction (X direction).

[0090] The second sealing plate 130 has a second covering portion 137. The second covering portion 137 covers at least a portion of the second end face 118 from the first direction (X direction). This makes it easy to stably position the second sealing plate 130 with respect to the case body 110. The second covering portion 137 in the present embodiment covers the entire surface of the second end face 118 from the first direction (X direction).

[0091] A first joint portion 140 is formed so as to straddle the outer peripheral surface portion 116 and the first covering portion 127. The first end surface 117 and the first covering portion 127 are joined by the first joint portion 140. A second joint portion 141 is formed so as to straddle the outer peripheral surface portion 116 and the second covering portion 137. The second end surface 118 and the second covering portion 137 are joined by the second joint portion 141. The first joint portion 140 and the second joint portion 141 are formed, for example, by laser welding. Note that the first joint portion 140 and the second joint portion 141 are not limited to laser welding, and may be joined by other joining methods such as ultrasonic welding or resistance welding.

[0092] 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 disposed at a location farther away from the resin insulating member provided between the electrode terminal 300 and the sealing plates 120, 130, compared to a case in which the entire sealing plate is inserted inside the case body and a joint portion is formed between the outer peripheral surface of the sealing plate and the end face of the case body. This makes it possible to reduce the thermal effect on the insulating member during joining.

[0093] Hereinafter, a secondary battery according to a comparative example will be described. Since the secondary battery according to this comparative example has a case structure different from that of the secondary battery 1 according to the embodiment of the present technology, the description of the configuration similar to that of the secondary battery 1 according to the embodiment of the present technology will not be repeated.

[0094] FIG. 18 is a perspective view showing a joined state between a case body and a first sealing plate included in a secondary battery according to a comparative example.

[0095] 18, the secondary battery 9 according to the comparative example includes a case 900. The case 900 includes a case main body 910 and a first sealing plate 920.

[0096] 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 an end portion on a first side in a first direction (X direction). The inner circumferential surface portion 919 extends around the axis of the case body 910 in the first direction (X direction) and toward the inside of the case body 910.

[0097] The first sealing plate 920 covers the first opening 913. The outer periphery of the first sealing plate 920 contacts an inner periphery 919 of the case body 910. The inner periphery 919 and the outer periphery of the first sealing plate 920 are joined by a first bonding portion 940. The first bonding portion 940 is formed so as to straddle the outer surface of the first sealing plate 920 and the end face of the case body 910.

[0098] When forming the first joint portion 940, when inserting the first sealing plate 920 into the inside of the case body 910, the first sealing plate 920 can be positioned at any position in the first direction (X direction), and therefore it is difficult to determine the position of the first sealing plate 920 in the first direction (X direction).

[0099] 17, in the present embodiment, first covering portion 127 of first sealing plate 120 can be abutted against first end surface 117 of case body 110, making it easy to position first sealing plate 120 with respect to case body 110. This makes it easy to join case body 110 and first sealing plate 120. Therefore, first joining portion 140 can be stably formed.

[0100] Hereinafter, a method for manufacturing a secondary battery according to the present embodiment will be described. Fig. 19 is a flowchart showing a method for manufacturing a secondary battery according to one embodiment. Fig. 20 is a bottom view showing a joining method when forming a case body. Note that the welding path in Fig. 20 is shown shifted from the position of the part that is actually welded in order to make the welding path easier to understand.

[0101] 19, in the method for manufacturing the secondary battery 1 according to the present embodiment, first, a case body is prepared (S1 step). In the step of preparing the case body 110 (S1 step), a plate-like member is bent into a cylindrical shape, and both ends of the plate-like member bent into a cylindrical shape are joined to each other to form a rectangular cylindrical member constituting the case body 110.

[0102] In joining both ends of the plate-like member, the energy beam can be irradiated in multiple steps to weld both ends of the plate-like member. However, it is not necessary to irradiate the energy beam in multiple steps. In this embodiment, the laser is irradiated in two steps to weld both ends of the plate-like member. This forms the joint 115.

[0103] Specifically, first, in a first laser irradiation, a laser (not shown) passes through welding path 115a in Fig. 20 in the direction of the arrow, and a first region R1 including an end portion on the first side of case body 110 is welded. Next, in a second laser irradiation, a laser passes through welding path 115b in Fig. 20 in the direction of the arrow, and a second region R2 including an end portion on the second side of case body 110 is welded.

[0104] In the welding of the first region R1 and the second region R2, the end of the first side and the end of the second side are the start point and end point of the welding. In this embodiment, the end of the first side and the end of the second side are the end point of the welding.

[0105] In the case of laser welding divided into two steps, the welding distance of one step can be made longer than the welding distance of the other step. 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 it possible to shorten the distance traveled from the end point of the welding path 115a to the start point of the welding path 115b compared to the case where the welding distances of both paths are the same. This makes it possible to shorten the distance over which the laser is not irradiated, thereby shortening the overall welding time.

[0106] FIG. 21 is a bottom view illustrating a joining method when molding a case body according to a first modified example of one embodiment.

[0107] In the first laser irradiation in this modification, a laser (not shown) passes through welding path 115c in the direction of the arrow in Fig. 21 to weld a second region R2 including an end portion on the second side of case body 110A. Next, in the second laser irradiation, a laser passes through welding path 115d in Fig. 21 in the direction of the arrow to weld a first region R1 including an end portion on the first side of case body 110A. This forms joint 115A.

[0108] In the method for joining the case body of the secondary battery according to this modification, the end of the first side and the end of the second side are the starting points of welding, which more effectively prevents the molten part from flowing toward the opening side of the case body 110A during welding, resulting in unstable contact with the sealing plate.

[0109] 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.

[0110] Next, the positive electrode tab group 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.

[0111] Next, the electrode body 200 is inserted into the case body 110 (step S3). As shown in Fig. 15, the electrode body 200 is inserted into the case body 110 by inserting the positive electrode current collector 420 from the first opening 113.

[0112] Next, the second electrode terminal and the electrode body are connected (step S4). In this embodiment, the positive electrode tab group 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.

[0113] The first spacer 600 and the second spacer are disposed between the electrode body 200 and the sealing plates 120, 130 after the electrode tabs are folded at any timing in the above-mentioned process.

[0114] Next, as shown in FIG. 19, the case body 110 and the sealing plates 120, 130 are temporarily joined together (step S5).

[0115] Prior to the step of sealing the first opening 113, a portion (first covering portion 127) covering at least a part of the first end surface 117 of the first opening 113 is temporarily joined to the first end surface 117. The temporary joining is performed by temporarily joining the sealing plate and the case body at points among the joining locations. The temporary joining in this embodiment is formed, for example, by joining one point on each of the four sides of the pair of first side surface portions 111 and the pair of second side surface portions 112. Note that the temporary joining may be, for example, a relatively short (for example, less than 1 cm) linear shape. Also, temporary joining is not necessarily performed.

[0116] FIG. 22 is a perspective view showing a method of joining a case body and a first sealing plate included in a secondary battery according to one embodiment.

[0117] 22, the first opening 113 is sealed (step S6), and the second opening 114 is sealed (step S6).

[0118] At least a part of the step of sealing first opening 113 and the step of sealing second opening 114 are performed simultaneously. In the present embodiment, the step of sealing first opening 113 and the step of sealing second opening 114 are performed so as to start and end at approximately the same time.

[0119] Note that the step of sealing first opening 113 and the step of sealing second opening 114 may partially overlap. Furthermore, these steps may start simultaneously but not necessarily end simultaneously, or may start simultaneously but not necessarily end simultaneously. When these steps partially overlap, it does not matter whether the sealing of first opening 113 or the sealing of second opening 114 is performed first.

[0120] First sealing plate 120 is abutted against first end face 117 so as to cover at least a portion of first end face 117 from a first direction (X direction), and a bonding process is performed from the outer periphery side around the axis in the first direction (X direction) to form a bonding portion spanning first sealing plate 120 and outer periphery surface portion 116 of case body 110, thereby sealing first opening 113.

[0121] As with the bonding of the first sealing plate 120, before the step of sealing the second opening 114, a portion covering at least a part of the second end face 118 of the second opening 114 is temporarily bonded to the second end face 118. The second sealing plate 130 is brought into contact with the second end face 118 so as to cover at least a part of the second end face 118 from the first direction (X direction), and a bonding process is performed from the outer periphery side around the axis in the first direction (X direction) to form a bonding portion spanning the second sealing plate 130 and the outer periphery surface portion 116 of the case body 110, thereby sealing the second opening 114. Note that temporary bonding is not necessarily performed.

[0122] FIG. 23 is a side view showing a state immediately after starting to join the case body and the first sealing plate. FIG. 24 is a side view showing a state in which the short side portions of the case body and the first sealing plate are joined while rotating. FIG. 25 is a side view showing a state in which the long side portions of the case body and the first sealing plate are joined while rotating. FIG. 26 is a bottom view showing a joining path when joining the case body and the first sealing plate. In FIGS. 23 to 25, only the case body is shown. In addition, in FIGS. 23 to 26, joining on the negative electrode side is illustrated as an example, and a similar joining method can be used for joining on the positive electrode side. Note that the welding path in FIG. 26 is shown shifted from the position of the part that is actually welded in order to make the welding path easier to understand.

[0123] 22 to 25, in at least one of the steps of sealing the first opening 113 and the step of sealing the second opening 114, the joining process can be performed by rotating the case body 110 around an axis in the first direction (X direction) (rotating in the r1 direction in FIG. 22). In this embodiment, in both of the steps 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 by the laser 3. The laser 3 may be of a pulsed type or a continuous oscillation type.

[0124] The case body 110 is pressed by a gripping device (not shown) until it is elastically deformed. As a result, the electrode body 200 is clamped by the case body 110. The case body 110 is pressed by the gripping device at the first side surface portion 111, which has a larger area than the second side surface portion 112. Note that the deformation of the case body 110 is not limited to elastic deformation. Also, an insulating sheet 700 may be interposed between the case body 110 and the electrode body 200.

[0125] In this embodiment, the joining process is performed while the case body 110 is continuously rotating. The focal length of the laser 3 is adjusted in accordance with the continuous rotation of the case body 110 by moving the joining device 2.

[0126] As shown in FIG. 26, laser welding is started from a position P1 shifted in the first direction (X direction) from the boundary between the outer peripheral surface portion 116 and the first covered portion 127. The laser passes through a welding path 116a inclined at 45° or more with respect to the first end face 117 when viewed from a direction intersecting the first direction (X direction). After that, the laser is continuously irradiated from the welding path 116a to the boundary between the outer peripheral surface portion 116 and the first covered portion 127. The laser passes through a welding path 116b at the boundary between the outer peripheral surface portion 116 and the first covered portion 127 to weld the entire circumference of the case 100 in the first direction (X direction). After welding until the welding path 116b overlaps, the laser is moved through the welding path 116c to a position P2 shifted 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 point and end point of the welding, making it possible to provide stable heat input when joining the case body 110 and the first sealing plate 120.

[0127] In this embodiment, position P1 is shifted from the boundary between outer circumferential surface portion 116 and first covered portion 127 toward case body 110 in the first direction (X direction), but may be shifted toward first sealing plate 120. In addition, the joining path in this embodiment is exemplified as having a case in which the start point and end point of welding are not included in the boundary between outer circumferential surface portion 116 and first covered portion 127, but is not limited to this configuration. The joining path may be configured such that at least one of the start point and end point of welding is at the boundary between outer circumferential surface portion 116 and first covered portion 127.

[0128] Next, a modified example of the joining process by laser welding will be described. Fig. 27 to Fig. 29 are bottom views showing first to third welding paths when joining the case body and the first sealing plate according to the modified example. Fig. 27 to Fig. 29 illustrate a state in which the first joining portion 140 is formed on the second side surface portion 112.

[0129] The first joint portion 140 according to the modified example is welded by irradiating the laser eight times. Specifically, the four flat surfaces of the pair of first side surface portions 111 and the pair of second side surface portions 112 of the outer circumferential surface portion 116, and the four corners between them, are individually laser welded. Note that irradiating the laser multiple times means that the laser is scanned multiple times, and does not mean that the amplitude of the pulsed laser is one by one.

[0130] 27, a part of the first joint portion 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, a laser is scanned along the boundary between the outer circumferential surface portion 116 and the first covering portion 127, and then the laser irradiation is stopped at a position shifted in the first direction (X direction).

[0131] 28, after the case body 110 is rotated and stopped, a part of the first joint portion 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) from the boundary between the outer circumferential surface portion 116 and the first covered portion 127, the boundary between the outer circumferential surface portion 116 and the first covered portion 127 is scanned with the laser, and then the laser irradiation is stopped at the position shifted in the first direction (X direction).

[0132] 29, after the case body 110 is rotated and stopped, a part of the first joint portion 140 is formed by the third welding path 116f. The third welding path 116f is a path in which, with the rotation of the case body 110 stopped, laser irradiation is started from a position shifted in the first direction (X direction) from the boundary between the outer circumferential surface portion 116 and the first covered portion 127, and the boundary between the outer circumferential surface portion 116 and the first covered portion 127 is scanned with the laser.

[0133] As described above, laser welding is performed with the case body 110 stopped from rotating, and then the case body 110 is rotated, and the next laser welding is performed with the case body 110 stopped from rotating. These operations are repeated eight times to form the first joint 140. When performing laser welding, the case body 110 is rotated 45° at a time so that the four flat parts or the four corner parts are located directly below the joining device when viewed from the first direction (X direction). The focal length of the laser welding is changed and adjusted every time the case body 110 is rotated. Note that, with the case body 110 stopped from rotating, the four flat parts of the pair of first side surface parts 111 and the pair of second side surface parts 112 of the outer circumferential surface part 116 can also be laser welded, and each of the four corner parts can be laser welded while rotating the case body 110.

[0134] As with the above-described welding paths in the present embodiment, the start points and end points of the multiple laser welding steps in this modification are shifted from the first direction (X direction). The joining paths of the multiple laser welding steps partially overlap in the direction along the first end surface 117. In this modification, for example, the first welding path 116d and the second welding path 116e partially overlap, and the second welding path 116e and the third welding path 116f partially overlap.

[0135] In this manner, by welding through irradiation with an energy ray (laser) multiple times, first sealing plate 120 and outer circumferential surface portion 116 of case body 110 are joined at multiple joints. Adjacent joints among the multiple joints are formed such that adjacent joints overlap each other in part, so that the entire circumference of case 100 in the first direction (X direction) is reliably joined.

[0136] After the above-mentioned steps have been carried out, an electrolyte is poured into the case 100 through the pouring hole, and the secondary battery 1 is completed.

[0137] Hereinafter, a secondary battery according to a second modified example of the embodiment will be described. The secondary battery according to this modified example has a joining structure between the case body and the sealing plate different from that of the secondary battery 1 according to the embodiment of the present technology, and therefore the description of the same configuration as that of the secondary battery 1 according to the embodiment of the present technology will not be repeated.

[0138] FIG. 30 is a perspective view showing a joined state between a case body and a first sealing plate included in a secondary battery according to a second modification of an embodiment.

[0139] A secondary battery 1B according to this modification includes a case 100B. The case 100B includes a case main body 110B and a first sealing plate 120B.

[0140] The case body 110B has an inner peripheral surface portion 119B. The inner peripheral surface portion 119B extends around an axis in a first direction (X direction).

[0141] The first sealing plate 120B has a first covering portion 127B and a first portion 128B. The first covering portion 127B covers the end portion on the first side of the case body 110B from the first direction (X direction). The first portion 128B enters the inside 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 bonding portion 140B is formed so as to straddle the first sealing plate 120B and the outer circumferential surface portion 116B.

[0142] First joint portion 140B is a welded portion formed by laser welding. In the process of sealing first opening 113B, first sealing plate 120B and first end surface 117 of case body 110B are welded to each other by irradiating a laser from the outer periphery side around the axis in the first direction (X direction) (DR1 direction in FIG. 30).

[0143] Since the first portion 128B is disposed to fit into the inner circumferential surface portion 119B of the case body 110B, the position of the first sealing plate 120B with respect to the case body 110B is more stable, and as a result, laser welding can be performed stably.

[0144] First sealing plate 120B has protrusion 129B on its outer surface. Protrusion 129B is provided adjacent to first covering portion 127B. This prevents the periphery of first covering portion 127B of first sealing plate 120B from melting excessively during laser welding, thereby preventing welding sagging or the like from occurring on the outer surface side.

[0145] In addition, although the configuration of the negative electrode side is shown in FIG. 30, the positive electrode side may have the same structure as the negative electrode side. In addition, the second sealing plate may have the same configuration as the first sealing plate 120B. Specifically, the second sealing plate has a second portion (not shown). The second portion enters the inside of the case body from the second opening and faces the inner peripheral surface portion 119B of the case body. The second joint portion is a welded portion formed by laser welding. The second sealing plate and the outer peripheral surface portion 116B of the case body 110B are welded to each other.

[0146] When the first joint 140B and the second joint are formed by laser welding, even if the laser enters the inner surface 119B of the case body 110B from the outer periphery side around the axis in the first direction (X direction) (in FIG. 30, the DR1 direction), the laser can be received by the first portion 128B, thereby preventing the laser from slipping out during laser welding.

[0147] In the secondary battery 1 and its manufacturing method according to an embodiment of the present technology, the first sealing plate 120 is disposed so as to abut against the first end surface 117 of the case body 110, and then the case body 110 and the first sealing plate 120 are joined together. This makes it possible to stably position the first sealing plate 120 relative to the case body 110 in the first direction (X direction) and stabilize the joined state of the joint, compared to a case in which the first sealing plate is inserted into the inner periphery of the case body and the case body and the sealing plate are joined together. This makes it possible to improve the reliability of the first joint portion 140 that joins the case body 110 and the first sealing plate 120. By adopting a similar configuration to the first sealing plate 120 on the second sealing plate 130 side, it is possible to improve the reliability of the second joint portion 141.

[0148] In the secondary battery 1 according to an embodiment of the present technology, by joining the case body 110 with the joints 115 extending in the first direction (X direction), a single metal plate can be folded and the folded ends can be joined together, so that the case body 110 can be efficiently manufactured. Also, by arranging the joints 115, the first joints 140, and the second joints 141 on the outer periphery side of the case body 110, the joints 115 can be formed from the outer periphery side of the case body 110 by one joining device, so that the case 100 can be efficiently joined.

[0149] In a secondary battery 1 according to one embodiment of the present technology, 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, the energy density of the electrode body 200 can be improved, thereby forming a secondary battery with excellent output characteristics.

[0150] In a secondary battery 1 according to one embodiment of the present technology, a negative electrode terminal 301 (first electrode terminal) and a positive electrode terminal 302 (second electrode terminal) are provided on the first sealing plate 120 and the second sealing plate 130, respectively, so that the secondary battery can be made low-profile when the secondary battery 1 is placed on a portion of the peripheral surface of the case body 110 as the bottom surface.

[0151] In the secondary battery 1 according to an embodiment of the present technology, the first spacer 600 and the second spacer can be used to prevent the electrode body 200 from being too close to the first sealing plate 120 and the second sealing plate 130. This allows the electrode body 200 to be configured not to be located directly below the joining position 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.

[0152] In a modified example of secondary battery 1 according to an embodiment of the present technology, by providing the sealing plate with portions (first portion 128B and second portion) that face the inner circumferential surface portion 119B of case body 110B, even if the laser used to weld the sealing plate and case body 110B passes from the welding position to the inner circumferential surface portion 119B side of case body 110B, first portion 128B and second portion of the sealing plate can receive the laser, thereby preventing the laser from leaking out during welding.

[0153] In the manufacturing method of the secondary battery 1 according to one embodiment of the present technology, each of the joint portion 115, the first joint portion 140, and the second joint portion 141 can be formed from the outer periphery side in the axial direction of the first direction (X direction), thereby enabling the case 100 to be manufactured efficiently.

[0154] In the manufacturing method of the secondary battery 1 according to the embodiment of the present technology, the laser for joining the case body 110 and the sealing plates 120, 130 is applied in multiple passes, dispersing the heat input to the case body 110 and reducing the thermal effect on the case body 110. Furthermore, by applying the laser in multiple passes, the stroke of the laser can be shortened, allowing the joining device to be made smaller.

[0155] In the manufacturing method of secondary battery 1 according to the embodiment of the present technology, a laser is irradiated in a plurality of times, and both the first end and the second end of joint 115 are set as the start point or end point of welding. This makes it possible to stably form joint 115 with a uniform joint state of the first end and the second end, compared to a configuration in which joint 115 is formed by a single joining and the first end and the second end of joint 115 are not uniformly joined at the start point or end point of welding.

[0156] In a manufacturing method of a secondary battery 1 according to one embodiment of the present technology, the first joint portion 140 and the second joint portion 141 can be formed while rotating the case body 110. Therefore, the joining device 2 can be made smaller and the secondary battery 1 can be manufactured more efficiently compared to a configuration in which the case body 110 is stationary and the joining device moves around the case body 110.

[0157] In a manufacturing method of a secondary battery 1 according to one embodiment of the present technology, the case body 110 is held by a manufacturing device to an extent that the case body 110 can clamp the electrode body 200, thereby preventing the electrode body 200 from moving inside the case body 110 when the case body 110 is rotated to join the case body 110, thereby suppressing damage to the electrode body 200.

[0158] In a manufacturing method of a secondary battery 1 according to one embodiment of the present technology, by performing temporary joining before joining the case body 110 and the sealing plates 120, 130, it is possible to suppress misalignment between the case body 110 and the sealing plates 120, 130 when rotating the case body 110 to join them.

[0159] In the method for manufacturing the secondary battery 1 according to the embodiment of the present technology, the first bonded portion 140 and the second bonded portion 141 are formed simultaneously, so that the secondary battery 1 can be manufactured efficiently.

[0160] Although the embodiment of the present technology has been described above, the embodiment disclosed herein should be considered as 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 scope and meaning equivalent to the claims. [Explanation of symbols]

[0161] 1,1B,9 Secondary battery, 2 Joining device, 100,100B,900 Case, 110,110B,910 Case body, 111 First side portion, 112 Second side portion, 113,113B,913 First opening, 114 Second opening, 115,115A Joint portion, 115a,115b,115c,115d,116a,116b,116c,116d Welding path, 116,116B Outer peripheral surface portion, 116d First welding path, 116e Second welding path, 116f Third welding path, 117,917 First end surface, 118 Second end surface, 119B,919 Inner peripheral surface portion, 120,120B,920 First sealing plate (sealing plate), 124,134 Injection hole, 125, 135 Gas exhaust valve, 127, 127B First covering portion, 128B First portion, 129B Convex portion, 130 Second sealing plate (sealing plate), 137 Second covering portion, 140, 140B, 940 First joint portion, 141 Second joint portion, 200, 201, 202 Electrode body, 210 Negative electrode plate, 210S Negative electrode base plate, 211 Negative electrode core, 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, 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 electrode terminal, 400, current collector, 410, negative electrode current collector, 420, positive electrode current collector, 430, first conductive member, 431, first flat portion, 432, second flat portion, 433, 434, 441, 454, joint portion, 435, step portion, 440, second conductive member, 510, first insulating member, 520, second insulating member, 600, first spacer, 610, first part, 620, second part, 630a, 630b, engagement portion, 700, insulating sheet, P1, P2, position, R1, first region, R2, second region.

Claims

1. An electrode assembly including a first electrode and a second electrode having a polarity different from that of the first electrode; A case for accommodating the electrode body, The case is a case body having a first opening located at an end of a first side in a first direction and a second opening located at an end of a second side opposite to the first side in the first direction; a first sealing plate that seals the first opening; a second sealing plate that seals the second opening, the case body has an outer circumferential surface portion extending around an axis in the first direction, a first end face located at an end of the first side and extending in a direction intersecting the first direction, and a second end face located at an end of the second side and extending in a direction intersecting the first direction, the first sealing plate has a first covering portion covering at least a portion of the first end surface from the first direction; the second sealing plate has a second covering portion covering at least a portion of the second end face from the first direction, A first bonding portion is formed so as to span the outer circumferential surface portion and the first covering portion, A secondary battery, comprising: a second joint portion formed across the outer circumferential 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 circumferential surface portion.

3. The electrode body is A main body portion, a first electrode tab group electrically connected to the first electrodes and located on the first side with respect to the main body portion; 3 . The secondary battery according to claim 1 , further comprising: a second electrode tab group electrically connected to the second electrodes and located on the second side with respect to the main body portion.

4. a first electrode terminal electrically connected to the first electrode and attached to the first sealing plate; 3 . The secondary battery according to claim 1 , further comprising: a second electrode terminal electrically connected to the second electrode and attached to the second sealing plate.

5. a first spacer between the electrode body and the first sealing plate; The secondary battery according to claim 1 , further comprising: a second spacer between the electrode body and the second sealing plate.

6. The case body has an inner circumferential surface portion extending around an axis in the first direction, the first sealing plate has a first portion that is indented inside the case body beyond the first opening and faces the inner circumferential surface portion of the case body, the second sealing plate has a second portion that is inwardly protruding from the second opening into the case body and faces the inner circumferential surface of the case body, The secondary battery according to claim 1 , wherein the first joint portion and the second joint portion are welded portions.

7. A step of preparing a case body having a first opening located at an end of a first side in a first direction, a second opening located at an end of a second side opposite the first side in the first direction, an outer circumferential surface portion extending around an 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 a second end face located at the end of the second side and extending in a direction intersecting the first direction; inserting an electrode body including a first electrode and a second electrode having a polarity different from that of the first electrode into the case body; a step of abutting a first sealing plate against the first end surface so as to cover at least a portion of the first end surface from the first direction, and performing a joining process from an outer periphery side around an axis in the first direction to form a joint portion spanning the first sealing plate and the outer periphery surface portion of the case main body, thereby sealing the first opening; abutting a second sealing plate against the second end surface so as to cover at least a portion of the second end surface from the first direction, and performing a joining process from an outer circumferential side around an axis in the first direction to form a joint spanning the second sealing plate and the outer circumferential surface of the case body, thereby sealing the second opening.

8. The method for manufacturing a secondary battery according to claim 7 , wherein the case body is formed by bending a plate-like member into a cylindrical shape and joining both ends of the plate-like member bent into a cylindrical shape to each other.

9. The method for producing a secondary battery according to claim 8 , wherein the step of joining the two ends of the plate-like member to each other includes welding the two ends by irradiating the two ends with energy rays in a plurality of separate steps.

10. The joining of the two ends of the plate-like member to each other includes welding by irradiating the two ends with an energy beam in a plurality of separate steps; The welding by irradiating the energy beam in a plurality of times is welding a first region including an end portion of the first side of the case body; and welding a second region including an end portion of the case body on the second side, In the welding of the first region and the second region, the end of the first side and the end of the second side become a start point or an end point of welding, When the end of the first side is a welding start point, the end of the second side is a welding start point, The method for manufacturing a secondary battery according to claim 8 , wherein when the end portion on the first side is an end point of welding, the end portion on the second side is an end point of welding.

11. 11. The method for manufacturing a secondary battery according to claim 7, wherein in the step of sealing the first opening, forming the joint portion includes welding by irradiating an energy ray a plurality of times.

12. by irradiating the energy beam a plurality of times to perform welding, the first sealing plate and the case body are joined together at a plurality of the joints, The method for manufacturing a secondary battery according to claim 11 , wherein adjacent ones of the plurality of joints are formed so that parts of the adjacent joints overlap with each other.

13. 9. The method for manufacturing a secondary battery according to claim 7, wherein at least one of the steps of sealing the first opening and the step of sealing the second opening includes a step of rotating the case body around an axis in the first direction.

14. 14. The method for manufacturing a secondary battery according to claim 13, wherein at least one of the steps of sealing the first opening and sealing the second opening includes pressing the case body until it is deformed, and sandwiching the electrode body by the case body.

15. a step of temporarily joining the first sealing plate and the case body before the step of sealing the first opening; The method for manufacturing a secondary battery according to claim 13 , further comprising the step of temporarily joining the second sealing plate and the case body before the step of sealing the second opening.

16. 9. The method for manufacturing a secondary battery according to claim 7, wherein at least a part of the step of sealing the first opening and the step of sealing the second opening are performed simultaneously.

17. The case body has an inner circumferential surface portion extending around an axis in the first direction, the first sealing plate has a first portion that is indented inside the case body beyond the first opening and faces the inner circumferential surface portion of the case body, the second sealing plate has a second portion that is inwardly protruding from the second opening into the case body and faces the inner circumferential surface of the case body, 9. The method for manufacturing a secondary battery according to claim 7 or 8, wherein in the step of sealing the first opening and the step of sealing the second opening, the first sealing plate and the case body are welded together, and the second sealing plate and the case body are welded together, by irradiating an energy ray from an outer circumferential side around an axis in the first direction.

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