Energy storage device and method for manufacturing the same

Abstract

To provide a method for manufacturing an energy storage device with high conductivity. [Solution] The present invention provides a method for manufacturing an energy storage device, comprising an electrode body including a first electrode, a case, and a first electrode terminal, wherein the case is rectangular in shape having a first wall to which the first electrode terminal is attached, and second to sixth walls, and at least one edge of the first wall is a bent portion. This manufacturing method includes a connection step of preparing a member 12p having a first portion P1 and at least one extension portion P2 to 6, attaching the first electrode terminal to the first portion P1 and electrically connecting the first electrode terminal to the first electrode, a bending step of bending the extension portions P2 to 6 perpendicular to the first portion P1 after the connection step, and a joining step of joining the wall defined in the bending step to an adjacent wall.

Description

Technical Field

[0001] The present invention relates to a power storage device and a method for manufacturing the same.

Background Art

[0002] Patent Documents 1 and 2 disclose a power storage device including an electrode body including a first electrode and a second electrode, a case accommodating the electrode body, and a first electrode terminal electrically connected to the first electrode and attached to the bottom wall of the case. Patent Document 1 describes that an electrode tab provided on the first electrode is joined to the first electrode terminal in the case by welding or the like.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] When the first electrode terminal is attached to the bottom wall of the case, the side wall of the case becomes an obstacle, making it difficult to stably join the electrode tab and the first electrode terminal. Therefore, it is required to form a highly reliable conduction path from the first electrode to the first electrode terminal.

[0005] The present invention has been made in view of the above circumstances, and its main object is to provide a power storage device with high conduction reliability.

Means for Solving the Problems

[0006] The present invention provides a method for manufacturing an energy storage device, comprising: an electrode body including a first electrode and a second electrode; a case housing the electrode body; and a first electrode terminal electrically connected to the first electrode, wherein the case is rectangular in shape and to which the first electrode terminal is attached, and has a first wall partitioned by a first edge, a second edge, a third edge, and a fourth edge; a second wall extending from the first edge; a third wall extending from the second edge; a fourth wall extending from the third edge; a fifth wall extending from the fourth edge; and a sixth wall facing the first wall, wherein at least one of the first edge, the second edge, the third edge, and the fourth edge is a bent portion formed by bending a member constituting the case. This manufacturing method includes: preparing a member having a first part that constitutes the first wall and at least one extension that extends from the first part and constitutes at least one of the second wall, third wall, fourth wall, and fifth wall; a connection step of attaching the first electrode terminal to the first part and electrically connecting the first electrode terminal to the first electrode; a bending step of bending the extension part after the connection step so that it is perpendicular to the first part and defines at least one of the second wall, third wall, fourth wall, and fifth wall; and a joining step of joining the wall defined in the bending step to an adjacent wall.

[0007] By performing the connection process before the bending process, the first electrode terminal can be attached to the first wall without being obstructed by the side wall of the case, and the first electrode terminal can be connected to the first electrode of the electrode body. Therefore, a stable conductive path can be formed between the first electrode terminal and the first electrode. Consequently, a highly conductive energy storage device can be realized. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic perspective view showing an energy storage device according to one embodiment. [Figure 2] Figure 2 is a schematic longitudinal cross-sectional view along the line II-II in Figure 1. [Figure 3]Figure 3 is a schematic longitudinal cross-sectional view along the line III-III in Figure 1. [Figure 4] Figure 4 is a schematic perspective view of the spacer. [Figure 5] Figure 5 is a magnified view of a portion of Figure 4. [Figure 6] Figure 6 is a schematic plan view showing a first plate material according to one embodiment. [Figure 7] Figure 7 is an explanatory diagram of the third step (Steps 1-3). [Figure 8] Figure 8 shows an example of a composite product obtained after the connection process. [Figure 9] Figure 9 is a modified version of Figure 4. [Figure 10] Figure 10 is a modified version of Figure 6. [Figure 11] Figure 11 is an explanatory diagram of the joining process related to a modified example. [Figure 12] Figures 12(A) to 12(F) are equivalent to Figure 6 in terms of modified examples. [Modes for carrying out the invention]

[0009] Hereinafter, several preferred embodiments of the technology disclosed herein will be described with reference to the drawings. Matters other than those specifically mentioned herein but necessary for carrying out the technology disclosed herein (e.g., general configuration and manufacturing processes of energy storage devices that do not characterize the technology disclosed herein) can be understood as design matters for those skilled in the art based on the prior art. The technology disclosed herein can be carried out based on the content disclosed herein and common technical knowledge in the art. Furthermore, the notation "A to B" indicating a range herein encompasses not only the meaning of "A or greater and B or less," but also the meanings of "greater than A" and "less than B."

[0010] [Energy storage device] Figure 1 is a schematic perspective view showing a power storage device 100 according to one embodiment. Figure 2 is a schematic longitudinal cross-sectional view along line II-II in Figure 1. Figure 3 is a schematic longitudinal cross-sectional view along line III-III in Figure 1. In the following description, the symbols L, R, F, Rr, U, and D in the drawings indicate left, right, front, back, top, and bottom. Also, the symbol X in the drawings indicates the short side direction (thickness direction) of the power storage device 100, the symbol Y indicates the long side direction of the power storage device 100 perpendicular to the short side direction, and the symbol Z indicates the up and down direction of the power storage device 100. The up and down direction Z may coincide with the vertical direction. However, these are merely directions for the convenience of explanation and do not limit the installation configuration of the power storage device 100 in any way.

[0011] In this specification, "energy storage device" refers to any device capable of repeated charging and discharging through the movement of charge carriers between a positive electrode and a negative electrode via an electrolyte. The electrolyte may be a liquid electrolyte, a gel electrolyte, or a solid electrolyte. The term "energy storage device" encompasses not only secondary batteries such as lithium-ion secondary batteries and nickel-metal hydride secondary batteries, but also capacitors that utilize chemical reactions, such as lithium-ion capacitors and pseudocapacitance capacitors.

[0012] As shown in Figure 2, the energy storage device 100 comprises a case 10, an electrode body 20, a positive electrode terminal 30, and a negative electrode terminal 40. The energy storage device 100 further comprises a positive electrode external conductive member 73, a negative electrode external conductive member 74, a spacer 80, and a liquid electrolyte (electrolyte, not shown). However, the positive electrode external conductive member 73, the negative electrode external conductive member 74, and the spacer 80 are not essential and can be omitted in other embodiments. The energy storage device 100 is a non-aqueous electrolyte secondary battery. Preferably, the energy storage device 100 is a secondary battery such as a lithium-ion secondary battery.

[0013] The case 10 is a housing that houses the electrode body 20. As shown in FIG. 1, the case 10 here has an outer shape that is flat and bottomed rectangular parallelepiped (rectangular). The material of the case 10 may be the same as that conventionally used, and there is no particular limitation. Preferably, the case 10 is made of metal, and more preferably, for example, it is made of aluminum, aluminum alloy, iron, iron alloy, or the like. The case 10 here includes a case body 12 and a sealing plate (lid body) 14. The case 10 has a size according to the size of the electrode body 20, the number of accommodated (one or more), and the like.

[0014] As shown in FIG. 2, the case body 12 is a rectangular container having an opening 12h on the upper surface here. Specifically, as shown in FIG. 1, the case body 12 is a bottomed rectangular tube shape and has a bottom wall 12a (first wall), a pair of long side walls 12b (second wall and third wall), a pair of short side walls 12c (fourth wall and fifth wall), and an opening 12h (see FIG. 2) facing the bottom wall 12a. The opening 12h is substantially rectangular here. The bottom wall 12a constitutes the lower surface of the case 10. The bottom wall 12a is substantially rectangular here. The bottom wall 12a is partitioned by a pair of long sides (first edge L1 and second edge L2) and a pair of short sides (third edge L3 and fourth edge L4). That is, the bottom wall 12a includes the first edge L1, the second edge L2, the third edge L3, and the fourth edge L4 on the outer peripheral portion.

[0015] In addition, in this specification, the term "substantially rectangular" includes, in addition to a perfect rectangular shape (rectangular shape), for example, a shape in which the corners connecting the long side and the short side of the rectangular shape are rounded into an R shape, a shape having a notch at the corner, and the like.

[0016] The pair of long side walls 12b and the pair of short side walls 12c constitute the side surfaces of the case 10. The pair of long side walls 12b and the pair of short side walls 12c each extend from the edges L1 to L4 of the bottom wall 12a. Specifically, the pair of long side walls 12b (the second wall and the third wall) each extend from the pair of long sides (the first edge L1 and the second edge L2) of the bottom wall 12a. The pair of long side walls 12b face each other in the short side direction X here. The pair of short side walls 12c (the fourth wall and the fifth wall) each extend from the pair of short sides (the third edge L3 and the fourth edge L4) of the bottom wall 12a. The pair of short side walls 12c face each other in the long side direction Y here. The pair of long side walls 12b each have a larger area than the pair of short side walls 12c.

[0017] In the technology disclosed herein, at least one of the four edges (the first edge L1, the second edge L2, the third edge L3, and the fourth edge L4) of the bottom wall 12a is not a welded joint (not welded) and is a bent portion formed by bending a member constituting the case 10. As will also be described in the manufacturing method described later, the bent portion is a portion (originally continuously connected portion) formed by bending a member (typically a plate material) constituting the case 10. By using at least one edge as the bent portion, a stable conduction path can be formed, and a power storage device 100 with high conduction reliability can be preferably realized.

[0018] In some embodiments, it is preferable that at least the boundary portions (that is, the first edge L1 and the second edge L2) between the bottom wall 12a and the pair of long side walls 12b among the four edges L1 to L4 of the bottom wall 12a are not welded joints but bent portions respectively. In other words, it is preferable that the pair of long side walls 12b are each continuously formed from the outer peripheral edges (edges L1, L2) of the bottom wall 12a. Further, among the four edges L1 to L4 of the bottom wall 12a, it is preferable that the number of welded joints is two or less, and more preferably one or less.

[0019] In particular, it is preferable that all four edges of the bottom wall 12a (first edge L1, second edge L2, third edge L3, and fourth edge L4) are bent sections rather than welded joints. In other words, it is preferable that the pair of long side walls 12b and the pair of short side walls 12c are formed continuously from the outer peripheral edge (edges L1 to L4) of the bottom wall 12a. By reducing the number of welded joints on the outer peripheral edge of the bottom wall 12a, for example, even if an external force is applied to the terminals (positive terminal 30 and / or negative terminal 40) when the energy storage device 100 is in use, a large load is less likely to be placed on the edges L1 to L4. Therefore, damage to the edges L1 to L4 can be suppressed, and the sealing performance and reliability of the case 10 can be improved.

[0020] In some embodiments, it is preferable that at least one of the four edges of the bottom wall 12a (first edge L1, second edge L2, third edge L3, and fourth edge L4) is a thin-walled portion. In particular, it is preferable that the edge that is a bent portion is a thin-walled portion (formed to be thin). For example, if all four edges L1 to L4 of the bottom wall 12a are bent portions, it is preferable that all four edges L1 to L4 are thin-walled portions. The thin-walled portion is a portion that is thinner than the other parts of the case 10 (for example, the main body portion of the bottom wall 12a (first wall), typically the thickness of the plate material constituting the case 10). The thickness of the thin-walled portion may be thinner than the sealing plate 14 (sixth wall). It is preferable that the thickness of the thin-walled portion is greater than or equal to the thickness of the welded joint 10w and / or welded joint 12w described later.

[0021] As shown in Figure 1, in this embodiment, a pair of long side walls 12b (second and third walls) are each bent perpendicular to the bottom wall 12a (first wall). A pair of short side walls 12c (fourth and fifth walls) are each bent perpendicular to the bottom wall 12a (first wall). The four edges of the bottom wall 12a (first edge L1, second edge L2, third edge L3, and fourth edge L4) are all bent portions. In this specification, "perpendicular" means a state in which two straight lines are arranged at an angle of 90°±10° (80°~100°), preferably at an angle of 90°±5° (85°~95°).

[0022] As can be seen from Figures 1 and 3, in this embodiment, the joints (butt joints, contact points; the same applies hereinafter) between the pair of long side walls 12b (second and third walls) and the pair of short side walls 12c (fourth and fifth walls) are welded together. More specifically, one long side wall 12b (second wall) is welded to the adjacent short side wall 12c (fourth and fifth walls). The other long side wall 12b (third wall) is welded to the adjacent short side wall 12c (fourth and fifth walls). In other words, in case 10, the four sides perpendicular to the bottom wall 12a (first wall) are welded joints 12w, rather than bent sections.

[0023] The sealing plate 14 constitutes the sixth wall of the case 10. The sealing plate 14 is attached to the case body 12 so as to seal the opening 12h of the case body 12. The sealing plate 14 is typically a plate-shaped member. The sealing plate 14 faces the bottom wall 12a (first wall) of the case body 12. The sealing plate 14 is roughly rectangular in this case. The sealing plate 14 constitutes the top surface of the case 10. Here, the sealing plate 14 is separate from the case body 12, but as described in the modified example (3) below, it may be an integral part of the case body 12.

[0024] In this embodiment, the case body 12 is a single component having a bottom wall 12a (first wall), a pair of long side walls 12b (second and third walls), a pair of short side walls 12c (fourth and fifth walls), and an opening 12h. The sealing plate 14 (sixth wall) is a separate component from the case body 12. The outer edge of the sealing plate 14 is welded to the periphery of the opening 12h of the case body 12. The outer edge of the sealing plate 14 is welded to the case body 12 continuously around its entire circumference. Specifically, the four edges of the sealing plate 14 and the boundary portions between them and the side walls of the case body 12 (the pair of long side walls 12b and the pair of short side walls 12c) are welded together. As shown in Figures 1 and 2, welded joints 10w are formed on the fitting portion between the case body 12 and the sealing plate 14, specifically on the four edges of the sealing plate 14 (here, a pair of long sides and a pair of short sides). The case 10 is integrated with the case body 12 by welding the sealing plate 14 to the periphery of the opening 12h. The case 10 is airtightly sealed.

[0025] As shown in Figure 2, the bottom wall 12a of the case body 12 is provided with an electrolyte injection hole 15, a gas discharge valve 17, and terminal lead-out holes 18 and 19. The electrolyte injection hole 15 is a through-hole for injecting electrolyte into the case 10 after the sealing plate 14 has been assembled to the case body 12. The electrolyte injection hole 15 is sealed by a sealing member 16 after the electrolyte has been injected. The gas discharge valve 17 is a thin-walled portion configured to rupture when the pressure inside the case 10 exceeds a predetermined value, thereby discharging gas from inside the case 10 to the outside. The terminal lead-out holes 18 and 19 are formed at both ends of the long side direction Y of the bottom wall 12a, respectively. The terminal lead-out holes 18 and 19 penetrate the bottom wall 12a. The positive electrode terminal 30 and the negative electrode terminal 40 are inserted through the terminal lead-out holes 18 and 19 of the bottom wall 12a, respectively.

[0026] The electrode body 20 is housed inside the case 10. As shown in Figure 3, in this embodiment, multiple (specifically two) electrode bodies 20 are housed inside one case 10. However, the number of electrode bodies 20 arranged inside one case 10 is not particularly limited; it may be one or three or more. As shown in Figures 2 and 3, the electrode body 20 is here covered by an electrode body holder 29 made of a resin sheet and is arranged inside the case 10. This prevents the electrode body 20 from coming into direct contact with the case body 12.

[0027] The material of the electrode holder 29 can be the same as that conventionally used, and there are no particular restrictions. Examples of such materials include polyolefin resins such as polypropylene (PP) and polyethylene (PE), and fluororesins such as perfluoroalkoxyalkanes and polytetrafluoroethylene (PTFE). Preferably, the electrode holder 29 has a heat-resistant layer at the locations facing the welded joint 12w (the four corners of case 10 in Figure 3). The heat-resistant layer is typically a layer containing an inorganic filler. As an inorganic filler, for example, ceramics such as alumina, boehmite, aluminum hydroxide, and titania can be used. This makes it difficult for heat to be transferred to the electrode body 20 when forming the welded joint 12w in the joining process (step 3) of the manufacturing method described later, thereby suppressing thermal damage to the electrode body 20. Furthermore, even if energy rays such as lasers leak to the electrode body 20 side or spatter is scattered, the electrode body 20 will be less likely to be damaged.

[0028] The electrode body 20 includes a positive electrode and a negative electrode. The configuration of the electrode body 20 may be the same as that of a general energy storage device (e.g., a lithium-ion secondary battery). In this embodiment, the electrode body 20 is a wound electrode body in which a strip-shaped positive electrode and a strip-shaped negative electrode are stacked in an insulated state via a strip-shaped separator and wound longitudinally around a winding axis. However, the electrode body 20 may also be a laminated electrode body in which a plurality of rectangular (typically rectangular) positive electrodes and a plurality of rectangular (typically rectangular) negative electrodes are stacked in an insulated state. One of the positive electrode and the negative electrode is an example of a "first electrode," and the other is an example of a "second electrode."

[0029] As shown in Figure 3, the electrode body 20 here has a flattened shape. The flattened electrode body 20 has a pair of curved portions 20r with curved outer surfaces and a pair of flat portions 20f with flat outer surfaces that connect the pair of curved portions 20r. The electrode body 20 here is housed inside the case 10 such that the winding axis direction is substantially the same as the vertical direction Z. Therefore, the pair of curved portions 20r face a pair of short side walls 12c of the case body 12. The pair of flat portions 20f face a long side wall 12b of the case body 12. The end face of the electrode body 20 (i.e., the laminated surface where the positive electrode and negative electrode are stacked) faces the bottom wall 12a and the sealing plate 14.

[0030] In some embodiments, the electrode body 20 is preferably flattened. This creates space at the four corners of the case 10, as shown in Figure 3, allowing the electrode body 20 to be separated from the welded joint 12w. Therefore, when forming the welded joint 12w in the joining process (step 3) of the manufacturing method described later, heat is less likely to be transferred to the electrode body 20, thereby suppressing thermal damage to the electrode body 20. Furthermore, even if energy rays such as lasers leak to the electrode body 20 side or spatter is scattered, the electrode body 20 is less likely to be damaged.

[0031] As shown in Figure 2, a convex positive electrode tab 27 is attached to the positive electrode of the electrode body 20. The positive electrode tab 27 is part of the positive electrode (specifically, the positive electrode current collector). As will be explained in detail in the section on the manufacturing method, the positive electrode tab 27 is bent and curved in the short-side direction X. The tip of the positive electrode tab 27 (the lower end in Figure 2) is directly connected (more specifically, joined) to the positive electrode terminal 30. The positive electrode tab 27 is connected to the positive electrode terminal 30 in a bent and curved state.

[0032] Furthermore, a convex negative electrode tab 28 is attached to the negative electrode of the electrode body 20. The negative electrode tab 28 is, in this case, part of the negative electrode (specifically, the negative electrode current collector). Similar to the positive electrode tab 27, the negative electrode tab 28 is bent and curved in the short-side direction X. The tip of the negative electrode tab 28 (the lower end in Figure 2) is directly connected (more specifically, joined) to the negative electrode terminal 40. The negative electrode tab 28 is connected to the negative electrode terminal 40 in this bent and curved state.

[0033] As the liquid electrolyte (electrolyte), any electrolyte that can be used in general energy storage devices (e.g., lithium-ion secondary batteries) can be used without particular limitations. One example is a non-aqueous electrolyte obtained by dissolving a support salt in a non-aqueous solvent. Examples of non-aqueous solvents include carbonate-based solvents such as ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. Examples of support salts include lithium salts such as LiPF6 and sodium salts such as NaPF6. The electrolyte may contain additives as needed. However, in other embodiments, the electrolyte may be in solid form (solid electrolyte) and integrated with the electrode body 20.

[0034] As shown in Figures 1 and 2, the positive terminal 30 and the negative terminal 40 are attached to the bottom wall 12a (first wall) of the case body 12, respectively. The positive terminal 30 is attached to one end of the long side direction Y of the bottom wall 12a (the left end in Figures 1 and 2). The negative terminal 40 is attached to the other end of the long side direction Y of the bottom wall 12a (the right end in Figures 1 and 2). It is preferable that both the positive terminal 30 and the negative terminal 40 are attached to the bottom wall 12a. However, in other embodiments, the bottom wall 12a may also serve as one of the terminals. When the positive electrode is the "first electrode", the positive terminal 30 is an example of the "first electrode terminal". When the negative electrode is the "first electrode", the negative terminal 40 is an example of the "first electrode terminal".

[0035] In case 10, the terminals (positive terminal 30 and / or negative terminal 40) are provided on the side opposite to the welded joint 10w between the case body 12 and the sealing plate 14. By providing the terminals (preferably the positive terminal 30 and the negative terminal 40) on the bottom wall 12a away from the welded joint 10w in this way, even if an external force is applied to the terminals when the energy storage device 100 is in use, for example, it is possible to suppress a large load on the welded joint 10w. Therefore, the welded joint 10w becomes less susceptible to damage, and the sealing performance and reliability of case 10 can be improved.

[0036] As shown in Figure 2, the positive electrode terminal 30 is inserted through a terminal exit hole 18 in the bottom wall 12a and extends from the inside to the outside of the case body 12. The positive electrode terminal 30 is electrically connected to the positive electrode of the electrode body 20. A portion of the positive electrode terminal 30 protrudes from the terminal exit hole 18 to the outer surface of the bottom wall 12a and is exposed to the outside of the case 10. The positive electrode terminal 30 is preferably made of metal, and more preferably of aluminum or an aluminum alloy. The positive electrode terminal 30 is insulated from the bottom wall 12a of the case body 12 by an insulating member (in this case, a gasket 90). The gasket 90 is preferably made of resin. The positive electrode terminal 30 has a flange portion 31 and an insertion portion 32.

[0037] The flange portion 31 is the part of the bottom wall 12a that has a larger outer diameter than the terminal lead-out hole 18. The flange portion 31 is located inside the case 10 (specifically the case body 12). The flange portion 31 is attached to the positive electrode tab 27. The flange portion 31 is directly connected to the positive electrode tab 27. The flange portion 31 is joined to the positive electrode tab 27 (for example, by welding such as ultrasonic welding). The flange portion 31 is flat and extends along the inner surface of the bottom wall 12a.

[0038] The insertion portion 32 extends from the flange portion 31 and is smaller in outer diameter than the terminal lead-out hole 18 of the bottom wall 12a. The insertion portion 32 is inserted through the terminal lead-out hole 18 of the bottom wall 12a. More specifically, the insertion portion 32 is inserted through the terminal through-hole 85 of the spacer 80 (described later), the through-hole of the gasket 90, the terminal lead-out hole 18 of the bottom wall 12a, and the through-hole of the positive electrode external conductive member 73. The insertion portion 32 is columnar, specifically cylindrical in shape. The insertion portion 32 is joined to the positive electrode external conductive member 73 on the outside of the case body 12 (on the outer surface side of the bottom wall 12a). The tip of the insertion portion 32 (the lower end in Figure 2) is crimped (riveted) to the positive electrode external conductive member 73 on the outside of the case 10 (more specifically, the case body 12). A crimped portion 30c is formed at the lower end of the insertion portion 32.

[0039] The positive electrode terminal 30 is fixed to the bottom wall 12a via a gasket 90 by a crimped portion 30c. The positive electrode terminal 30 is joined to the positive electrode external conductive member 73 by a crimped portion 30c. However, in other embodiments, the positive electrode terminal 30 may be joined to the positive electrode external conductive member 73 by a joining method other than crimping (for example, metal joining such as welding). Alternatively, crimping and metal joining (for example, welding) may be combined. The welding method is not particularly limited and may include, for example, laser welding, electron beam welding, ultrasonic welding, resistance welding, etc.

[0040] Furthermore, although the positive electrode terminal 30 is directly connected to the positive electrode tab 27 in this embodiment, in other embodiments, the positive electrode terminal 30 may be electrically connected to the positive electrode of the electrode body 20 via another conductive member (positive electrode current collector). In that case, the positive electrode terminal 30 may be joined to the positive electrode current collector inside the case body 12 by the joining method described above (for example, metal joining such as crimping and / or welding). Also, if the bottom wall 12a serves as the positive electrode terminal 30, the positive electrode terminal 30 may be electrically connected to the bottom wall 12a directly or via another conductive member.

[0041] The positive electrode external conductive member 73 is electrically connected to the positive electrode terminal 30 outside the case 10. The positive electrode external conductive member 73 is attached to the bottom wall 12a insulated from the bottom wall 12a by a gasket 90. The positive electrode external conductive member 73 is plate-shaped in this case. As shown in Figure 1, the positive electrode external conductive member 73 is substantially rectangular in shape, with the longer side Y being longer. The positive electrode external conductive member 73 is preferably made of metal, and more preferably of aluminum or an aluminum alloy.

[0042] As shown in Figure 2, the negative electrode terminal 40 is inserted through a terminal exit hole 19 in the bottom wall 12a and extends from the inside to the outside of the case body 12. The negative electrode terminal 40 is electrically connected to the negative electrode of the electrode body 20. A portion of the negative electrode terminal 40 protrudes from the terminal exit hole 19 to the outer surface of the bottom wall 12a and is exposed to the outside of the case 10. The negative electrode terminal 40 is preferably made of metal, and more preferably of copper or a copper alloy. The negative electrode terminal 40 is insulated from the bottom wall 12a of the case body 12 by an insulating member (in this case, a gasket 90). The specific configuration of the negative electrode terminal 40 may be the same as that of the positive electrode terminal 30. The negative electrode terminal 40 has a flange portion 41 and an insertion portion 42.

[0043] The flange portion 41 is the part of the bottom wall 12a that has a larger outer diameter than the terminal lead-out hole 19. The flange portion 41 is located inside the case 10 (more specifically, the case body 12). The flange portion 41 is attached to the negative electrode tab 28. The flange portion 41 is directly connected to the negative electrode tab 28. The flange portion 41 is joined to the negative electrode tab 28 (for example, by welding such as ultrasonic welding). The flange portion 41 is flat and extends along the inner surface of the bottom wall 12a.

[0044] The insertion portion 42 extends from the flange portion 41 and is smaller in outer diameter than the terminal lead hole 19 of the bottom wall 12a. The insertion portion 42 is inserted through the terminal lead hole 19 of the bottom wall 12a. More specifically, the insertion portion 42 is inserted through the terminal through hole 86 of the spacer 80 (described later), the through hole of the gasket 90, the terminal lead hole 19 of the bottom wall 12a, and the through hole of the negative electrode external conductive member 74. The insertion portion 42 is columnar, specifically cylindrical in shape. The insertion portion 42 is joined to the negative electrode external conductive member 74 on the outside of the case body 12 (on the outer surface side of the bottom wall 12a). The tip of the insertion portion 42 (the lower end in Figure 2) is crimped (riveted) to the negative electrode external conductive member 74 on the outside of the case 10 (more specifically, the case body 12). A crimped portion 40c is formed at the lower end of the insertion portion 42.

[0045] In this embodiment, the negative electrode terminal 40 is fixed to the bottom wall 12a via a gasket 90 by a crimped portion 40c. In this embodiment, the negative electrode terminal 40 is joined to the negative electrode external conductive member 74 by a crimped portion 30c. However, in other embodiments, the negative electrode terminal 40 may be joined to the negative electrode external conductive member 74 by a joining method other than crimping, similar to the positive electrode terminal 30. The negative electrode terminal 40 may also be electrically connected to the negative electrode of the electrode body 20 via another conductive member (negative electrode current collector). In that case, the negative electrode terminal 40 may be joined to the negative electrode current collector inside the case body 12 by the joining method described above. Furthermore, if the bottom wall 12a also serves as the negative electrode terminal 40, the negative electrode terminal 40 may be electrically connected to the bottom wall 12a directly or via another conductive member.

[0046] The negative electrode external conductive member 74 is electrically connected to the negative electrode terminal 40 outside the case 10. The negative electrode external conductive member 74 is attached to the bottom wall 12a insulated from the bottom wall 12a by a gasket 90. The negative electrode external conductive member 74 is plate-shaped in this case. As shown in Figure 1, the negative electrode external conductive member 74 is substantially rectangular in shape, with the long side direction Y being long. The negative electrode external conductive member 74 is preferably made of metal, and more preferably of copper or a copper alloy, for example.

[0047] As shown in Figure 2, the spacer 80 is positioned inside the case 10 between the bottom wall 12a (first wall, more specifically the inner surface, the upper surface in Figure 2) and the electrode body 20 (more specifically the lower surface in Figure 2). The spacer 80 is typically insulating and preferably made of resin. The material of the spacer 80 (at least the base portion 89, which will be described later) is preferably polyphenylene sulfide resin (PPS), fluororesin such as polytetrafluoroethylene (PTFE), or polyolefin resin such as polypropylene (PP) or polyethylene (PE). Among these, PPS is preferred from the viewpoint of mechanical strength and heat resistance.

[0048] Figure 4 is a schematic perspective view of the spacer 80. The case 10 is also shown in Figure 4 with dashed lines. The electrolyte injection hole 15 and gas discharge valve 17 are omitted from the illustration. As shown in Figure 4, the spacer 80 has a base portion 89 extending along the bottom wall 12a (first wall), and a pair of long-side periphery wall portions 81 and a pair of short-side periphery wall portions 82 (periphery wall portions) protruding from the outer peripheral edge of the base portion 89. The periphery wall portions can function as guides when defining the side walls of the case 10 (at least one of the pair of long side walls 12b and the pair of short side walls 12c) in the bending process (step 2) of the manufacturing method described later. That is, the first plate material 12p (see Figure 6) can be bent along the periphery wall portions, improving processability and workability. It is preferable that the long-side periphery wall portions 81 and the pair of short-side periphery wall portions 82 (periphery wall portions) are continuous and annular. However, it may be divided into a long side wall 12b (long side) and a short side wall 12c (short side), or it may be partially cut out.

[0049] The base portion 89 is flat. In an XY plan view, the base portion 89 is approximately rectangular. The outer shape of the base portion 89 is the same as the outer shape of the bottom wall 12a (manufacturing tolerances are acceptable). The base portion 89 is provided with a pair of terminal through holes 85 and 86, and a central through hole 87. As shown in Figure 2, the positive electrode terminal 30 (specifically, the columnar insertion portion 32) is inserted through the terminal through hole 85. The negative electrode terminal 40 (specifically, the columnar insertion portion 42) is inserted through the terminal through hole 86. The central through hole 87 is provided in the portion opposite to the electrolyte injection hole 15 and the gas discharge valve 17 (the portion that overlaps in an XY plan view). In the vertical Z direction, the electrolyte injection hole 15 and the gas discharge valve 17 are directly opposite to the electrode body 20 (or electrode body holder 29), respectively.

[0050] A pair of long-side perimeter walls 81 are provided at a pair of ends of the base portion 89 in the short-side direction X. Here, since the outer shape of the base portion 89 is the same as the outer shape of the bottom wall 12a, the pair of long-side perimeter walls 81 extend in the long-side direction Y along a pair of long sides (first edge L1 and second edge L2, see Figure 1) of the bottom wall 12a. The long-side perimeter walls 81 extend upward (away from the bottom wall 12a (first wall)). The pair of long-side perimeter walls 81 face a pair of long side walls 12b (second wall and third wall) of the case 10, respectively. The long-side perimeter walls 81 extend along the long side walls 12b. It is preferable that the long-side perimeter walls 81 abut against the long side walls 12b. The long side perimeter wall portion 81 can function as a guide when defining the long side wall 12b (second wall and / or third wall) in the bending process described later.

[0051] A pair of short-side perimeter walls 82 are provided at a pair of ends of the base portion 89 in the long-side direction Y. Here, since the outer shape of the base portion 89 is the same as the outer shape of the bottom wall 12a, the pair of short-side perimeter walls 82 extend in the short-side direction X along a pair of short sides of the bottom wall 12a (third edge L3 and fourth edge L4, see Figure 1). The short-side perimeter walls 82 extend upward (away from the bottom wall 12a (first wall)). The pair of short-side perimeter walls 82 face a pair of short side walls 12c (fourth wall and fifth wall) of the case 10, respectively. The short-side perimeter walls 82 extend along the short side walls 12c. It is preferable that the short-side perimeter walls 82 are in contact with the short side walls 12c. The short-side peripheral wall portion 82 can function as a guide when defining the short side wall 12c (fourth wall and / or fifth wall) in the bending process described later.

[0052] In this embodiment, the spacer 80 has a pair of long-side periphery wall portions 81 and a pair of short-side periphery wall portions 82 as periphery wall portions. However, as described above, the periphery wall portions can function when the first plate material 12p (see Figure 6) is bent in the bending process (step 2) to define the side walls of the case 10. Therefore, periphery wall portions are not required in areas that are not bent in the bending process (areas that are welded together).

[0053] In this embodiment, each of the pair of long-side peripheral wall portions 81 is connected to a pair of short-side peripheral wall portions 82 at both ends in the long-side direction Y. The peripheral wall portions are formed in a square shape (a rectangular shape with a hollow center) when viewed from above. This improves the mechanical strength of the peripheral wall portions, making it easier to strongly bend the first plate material 12p (see Figure 6) in the bending process (step 2) of the manufacturing method described later. Thus, processability and workability can be improved.

[0054] In this embodiment, the peripheral wall portion (a pair of long-side peripheral wall portions 81 and / or a pair of short-side peripheral wall portions 82) has reinforcing ribs 81r, 82r on the inner side (the side facing the electrode body 20) that connect the peripheral wall portion and the base portion 89 (see also Figure 6). The presence of the reinforcing ribs 81r, 82r improves the mechanical strength of the peripheral wall portion, making it easier to strongly bend the first plate material 12p (see Figure 6) in the bending process (step 2) of the manufacturing method described later. Thus, processability and workability can be improved.

[0055] The reinforcing rib 81r is composed of multiple members and is provided at predetermined intervals (spaced positions) along the long side direction Y. The reinforcing rib 82r is composed of multiple members and is provided at predetermined intervals (spaced positions) along the short side direction X. However, in other embodiments, the reinforcing ribs 81r and 82r may be a single long rod-shaped member, or they may be omitted if, for example, the peripheral wall is formed in a triangular shape in cross-section and the mechanical strength is sufficiently high.

[0056] Figure 5 is a partially enlarged view of Figure 4. In Figure 5, the short side peripheral wall portion 82 on the near side is shown as a hidden line (dashed line). As shown in Figure 5, on the outer surface side of the spacer 80 (the side facing the case body 12), it is preferable that the outer peripheral edge of the base portion 89 (the connecting portion between the base portion 89 and the long side peripheral wall portion 81 or the short side peripheral wall portion 82) has a rounded corner (R shape). This makes it easier to bend the first plate material 12p (see Figure 6) along the R shape in the bending process (step 2) of the manufacturing method described later. Thus, processability and workability can be improved.

[0057] In this embodiment, the spacer 80 is a single component, but in other embodiments, the spacer 80 may be composed of multiple components arranged at spaced-apart positions. Also, in this embodiment, the spacer 80 is placed only between the bottom wall 12a and the electrode body 20, but in other embodiments, a second spacer may be placed on the opening 12h side of the case body 12 (between the sealing plate 14 and the electrode body 20).

[0058] [Manufacturing method for energy storage devices] The energy storage device 100 of this embodiment can be manufactured by a method including, for example, the following steps: (Step 1) connection step; (Step 2) bending step; (Step 3) joining step; (Step 4) sealing step. The manufacturing method disclosed herein may also include other steps at any stage. For example, after (Step 4) sealing step, a step of pouring electrolyte into the case 10 may be included.

[0059] (Step 1) The connection process here includes, in this order: (Step 1-1) the first step of preparing the components constituting the case 10; (Step 1-2) the second step of preparing the electrode body 20; (Step 1-3) the third step of arranging the spacers; and (Step 1-4) the fourth step of forming a conductive path from the first electrode to the first electrode terminal. However, the order of (Step 1-1) the first step and (Step 1-2) the second step may be reversed or performed approximately simultaneously. Also, the order of (Step 1-3) the third step and (Step 1-4) the fourth step may be reversed or performed approximately simultaneously. Furthermore, (Step 1-3) the third step is not mandatory and may be omitted in other embodiments.

[0060] (Step 1-1) In the first step, the components constituting the case 10 are prepared. The components constituting the case 10 are typically plate materials. The plate material is preferably made of metal (i.e., a metal plate), and more preferably made of, for example, iron, an iron alloy such as stainless steel, aluminum, an aluminum alloy, etc. The plate material to be prepared has a first portion that constitutes the bottom wall 12a (first wall), and at least one extension portion that extends from the first portion and constitutes at least one side wall of the case 10 (at least one of the second wall, third wall, fourth wall, and fifth wall). In this embodiment, a first plate material that constitutes the case body 12 (first to fifth walls of the case 10) and a second plate material that constitutes the sealing plate 14 (sixth wall of the case 10) are prepared. Although not shown in the illustration, the second plate material here is flat. In this embodiment, two boards are prepared, but as described in the modified example (3) below, one board may be prepared, or three or more boards may be prepared.

[0061] Figure 6 is a schematic plan view showing the first plate material 12p according to one embodiment. Note that the electrolyte injection hole 15 and the gas discharge valve 17 are not shown in Figure 6. The first plate material 12p is flat in shape. The first plate material 12p has a substantially uniform thickness (plate thickness) except for the four edges L1 to L4 which will be described later. Although not particularly limited, the thickness of the first plate material 12p is preferably about 0.1 to 2 mm, more preferably 0.2 to 1 mm, and even more preferably 0.4 to 0.8 mm, from the viewpoint of rigidity (bendability), mechanical strength, durability, etc. The thickness of the first plate material 12p may be the same as the thickness of the second plate material constituting the sealing plate 14, or it may be thinner than the thickness of the second plate material.

[0062] As shown in Figure 6, the first plate material 12p of this embodiment has a first portion P1 that constitutes the bottom wall 12a (first wall) and four extension portions P2 to P5 that extend from the first portion P1. More specifically, the first plate material 12p has, as extension portions, second and third extension portions P2 and P3 that constitute a pair of long side walls 12b (second and third walls) and fourth and fifth extension portions P4 and P5 that constitute a pair of short side walls 12c (fourth and fifth walls). The first portion P1 is substantially rectangular and has a pair of long sides (first edge L1 and second edge L2) and a pair of short sides (third edge L3 and fourth edge L4). The first portion P1 is divided by four edges L1 to L4. Terminal exit holes 18 and 19 are provided in the first portion P1.

[0063] The second and third extensions P2 and P3 here extend continuously from a pair of long sides (first edge L1 and second edge L2) of the first part P1, respectively. The second and third extensions P2 and P3 here extend horizontally (including approximately horizontally, manufacturing tolerances etc. are permissible) to the first part P1. The fourth and fifth extensions P4 and P5 here extend continuously from a pair of short sides (third edge L3 and fourth edge L4) of the first part P1, respectively. The fourth and fifth extensions P4 and P5 here extend horizontally to the first part P1.

[0064] The four edges L1 to L4 constitute the outer periphery of the first portion P1 (the boundary between the first portion P1 and the second to fifth extension portions P2 to P5). Edges L1 to L4 indicate the locations to be bent in the bending process (Step 2) described later. As shown by the dashed lines in Figure 6, in this embodiment, the four edges L1 to L4 are formed to be thinner than the thickness of the first plate material 12p, for example, by notches or notches. This makes it easier to bend the first plate material 12p along the edges L1 to L4 in the bending process (Step 2) described later, thereby improving bending accuracy. However, in other embodiments, some or all of the four edges L1 to L4 of the first portion P1 may be the same thickness as the thickness of the first plate material 12p.

[0065] In some embodiments, terminals (positive terminal 30 and / or negative terminal 40) may be pre-attached to the terminal lead-out holes 18, 19 of the first portion P1. The terminals may be attached to the first portion P1 in an insulated manner from the first portion P1 via an insulating member (here, a gasket 90). That is, the first plate material 12p may be prepared as a single molded product integrated with the gasket 90 and the terminals (positive terminal 30 and / or negative terminal 40).

[0066] (Step 1-2) In the second step, the electrode body 20 is prepared. The electrode body 20 may be a purchased item supplied by a supplier, etc., or it may be manufactured in-house. The electrode body 20 may be a wound electrode body or a laminated electrode body. In one example, first, a strip-shaped positive electrode and a strip-shaped negative electrode are laminated with a strip-shaped separator in between, and then wound in the longitudinal direction around a winding axis to form a cylindrical shape. Next, the cylindrical wound electrode body (cylindrical body) is, for example, press-molded into a flat shape to produce a flat electrode body 20. The prepared electrode body 20 is then inserted into the electrode body holder 29.

[0067] (Step 1-3) In the third step, before the bending step (Step 2), the spacer 80 is placed on the first portion P1 of the first sheet material 12p. In this embodiment, the spacer 80 is placed before the fourth step (Step 1-4) (more specifically, between the first step (Step 1-1) and the fourth step (Step 1-4)). However, in other embodiments, the spacer 80 may be pre-attached (fixed) to the first portion P1 of the first sheet material 12p prepared in the first step (Step 1-1), or it may be placed after the fourth step (Step 1-4).

[0068] Figure 7 is an explanatory diagram of this process. As shown in Figure 7, the spacer 80 of this embodiment has a base portion 89 extending along the first portion P1, and a pair of long-side peripheral wall portions 81 and a pair of short-side peripheral wall portions 82 (peripheral wall portions) protruding from the outer peripheral edge of the base portion 89. The outer shape of the base portion 89 is the same as the outer shape of the first portion P1. Terminal through holes 85 and 86 are provided in the base portion 89. The spacer 80 is placed on the first portion P1 such that the terminal through holes 85 and 86 of the base portion 89 overlap with the terminal exit holes 18 and 19 of the first plate material 12p.

[0069] When the spacer 80 is placed on the first portion P1, the peripheral wall portion overlaps the edges L1 to L4 of the first plate material 12p. In this embodiment, the peripheral wall portion (a pair of long-side peripheral wall portions 81 and a pair of short-side peripheral wall portions 82) has reinforcing ribs 81r, 82r that connect the peripheral wall portion to the base portion 89. When the spacer 80 is placed on the first portion P1, the reinforcing ribs 81r, 82r are positioned along the edges L1 to L4 of the first plate material 12p.

[0070] (Steps 1-4) In the fourth step, the first electrode terminal (positive electrode terminal 30 or negative electrode terminal 40) is attached to the first part P1, and the first electrode terminal is electrically connected to the first electrode (positive or negative electrode) of the electrode body 20. That is, a conductive path is formed from the first electrode to the first electrode terminal. By performing this step before the bending step (Step 2) described later, the first electrode terminal can be attached to the first part P1 without being obstructed by the side walls (second to fifth walls) of the case 10. Also, the first electrode terminal of the first part P1 can be electrically connected to the first electrode without being obstructed by the side walls (second to fifth walls) of the case 10. Therefore, a conductive path between the first electrode terminal and the first electrode can be stably formed. Consequently, a highly conductive energy storage device 100 can be realized.

[0071] In this embodiment, conductive paths are formed on both the positive and negative sides. Specifically, a positive terminal 30 is attached to the first portion P1, and the positive terminal 30 attached to the first portion P1 is electrically connected to the positive electrode of the electrode body 20 (specifically, the positive electrode tab 27). Also, a negative terminal 40 is attached to the first portion P1, and the negative terminal 40 attached to the first portion P1 is electrically connected to the negative electrode of the electrode body 20 (specifically, the negative electrode tab 28). This creates a composite object of the first plate material 12p, the electrode body 20, and the terminal (positive terminal 30 or negative terminal 40). Figure 8 shows an example of the composite object obtained after this process. Note that the spacer 80 is not shown in Figure 8. The following explanation will use the positive electrode side as an example, referring to Figure 8, but the negative electrode side can be done similarly.

[0072] In one example, first, at least a portion (here, the insertion portion 32) of the positive electrode terminal 30 is inserted into a terminal lead-out hole 18 provided in the first portion P1 of the first plate material 12p, while being insulated from the first portion P1 via, for example, an insulating member (here, a gasket 90). Then, the positive electrode terminal 30 is joined to the area around the terminal lead-out hole 18 of the first portion P1. Here, it is crimped to the positive electrode external conductive member 73. In this way, the positive electrode terminal 30 is attached to the first portion P1 (together with the positive electrode external conductive member 73). Next, the positive electrode tab 27 of the electrode body 20 is electrically connected (joined) to the positive electrode terminal 30 (here, the flange portion 31) attached to the first portion P1, either directly or via another conductive member (positive electrode current collector). The joining of the positive electrode tab 27 can be done by welding, such as laser welding, electron beam welding, ultrasonic welding, or resistance welding.

[0073] However, the positive electrode terminal 30 does not necessarily have to be attached to the first part P1 beforehand. In another example, the positive electrode tab 27 of the electrode body 20 may first be electrically connected (joined) to another conductive member (positive electrode current collector), and then the positive electrode current collector and the positive electrode terminal 30 may be attached to the first part P1 at the same time (approximately simultaneously). In this way, the combined product can be obtained.

[0074] In this embodiment, a flat first plate material 12p was prepared in the first step (Step 1-1), but in other embodiments, one, two, or three of the four extension portions (second to fifth extension portions P2 to P5) of the first plate material 12p may be pre-bent before the bending step (Step 2), for example, before the third step (Step 1-3) or the fourth step (Step 1-4). In one example, two opposing extension portions of the four extension portions (second to fifth extension portions P2 to P5) of the first plate material 12p may be pre-bent. Furthermore, pre-bent extension portions may be pre-joined (preferably by welding) with adjacent extension portions.

[0075] (Step 2) In the bending process, after the connecting process (Step 1), the extended portion of the first sheet metal 12p (at least one of the second to fifth extended portions P2 to P5) is bent perpendicular to the first portion P1, thereby defining (dividing and forming) the side wall of the case 10 (at least one of the second wall, third wall, fourth wall, and fifth wall). This process can be carried out using a conventionally known sheet metal bending machine or the like.

[0076] In this embodiment, in the first step (Step 1-1), a flat first plate material 12p is prepared, and four extension portions (second to fifth extension portions P2 to P5) are bent so that they are perpendicular to the first portion P1, thereby defining all four side walls of the case 10 (second wall, third wall, fourth wall, and fifth wall). As a result, the first plate material 12p is formed into a bottomed rectangular tube shape, defining the case body 12. The electrode body 20 is positioned to overlap with the first portion P1 (first wall) and is enclosed by the four side walls. The electrode tabs of the electrode body 20 (positive electrode tab 27 and negative electrode tab 28) are bent and curved in the short side direction X (see also Figure 8). By bending the four extension portions in this step, the side walls of the case 10 become less of an obstruction in the fourth step (Step 1-4), thereby improving processability and workability. This, in turn, makes it easier to form a more stable conductive path between the first electrode terminal and the first electrode.

[0077] However, if some extensions have already been bent during the (Step 1) connection process, only the extensions that are not perpendicular to the first part P1 need to be bent in this process. For example, if a pair of opposing extensions of the first plate material 12p (e.g., the fourth and fifth extensions P4 and P5) have already been bent, only the remaining pair of extensions (e.g., the second and third extensions P2 and P3) need to be bent in this process.

[0078] In this embodiment, when bending the extended portion (at least one of the second to fifth extended portions P2 to P5), the spacer 80 placed on the first portion P1 can be used as a guide. That is, at least one extended portion of the first plate material 12p can be bent along the spacer 80. More specifically, the extended portion can be bent along the peripheral wall portion of the spacer 80 (a pair of long-side peripheral wall portions 81 and / or a pair of short-side peripheral wall portions 82). This improves the workability and bending accuracy of this process.

[0079] (Step 3) In the joining process, the walls defined in the (Step 2) bending process are joined to adjacent walls among the extensions (second to fifth extensions P2 to P5) of the first plate material 12p. In other words, at least one extension that was bent in the (Step 2) bending process is joined to an adjacent extension. For example, if the second extension P2 of the first plate material 12p is bent in the bending process to define a second wall, the fourth extension P4 (fourth wall) and the fifth extension P5 (fifth wall) adjacent to the second extension P2 (second wall) are joined to the second extension P2 (second wall), respectively. This forms a linear welded joint 12w.

[0080] In this embodiment, in the (Step 2) bending process, all four extensions (second to fifth extensions P2 to P5) are bent. Therefore, in this embodiment, this process includes (Step 4-1) joining the joint between the second extension P2 (second wall) and the fourth extension P4 (fourth wall) in a linear manner, (Step 4-2) joining the joint between the second extension P2 (second wall) and the fifth extension P5 (fifth wall) in a linear manner, (Step 4-3) joining the joint between the third extension P3 (third wall) and the fourth extension P4 (fourth wall) in a linear manner, and (Step 4-4) joining the joint between the third extension P3 (third wall) and the fifth extension P5 (fifth wall) in a linear manner. In this embodiment, a total of four welded joints 12w perpendicular to the first portion P1 (first wall) are formed.

[0081] The welding method is not particularly limited and may include, for example, laser welding, electron beam welding, ultrasonic welding, resistance welding, etc. In some embodiments, it is preferable to join the case body 12 by irradiating it with an energy ray such as a laser from the outside. The joining conditions may also be the same as in the conventional method and are not particularly limited. It is preferable to join the extension portions (walls) to be joined by pressing them together using a pressing jig or the like, and bringing them into stable contact. The case body 12 can be formed in the manner described above.

[0082] (Step 4) In the sealing process, the sealing plate 14 is fitted into the opening 12h of the case body 12, and the periphery of the opening 12h of the case body 12 and the sealing plate 14 are joined. This forms a welded joint 10w and seals the case 10. The welding method may be the same as in the conventional method and is not particularly limited. In some embodiments, it is preferable to weld the case body 12 and the sealing plate 14 by irradiating the fitting portion of the case body 12 and the sealing plate 14 along the periphery of the opening 12h with an energy ray such as a laser. The energy storage device 100 can be manufactured in this manner.

[0083] <Applications of energy storage devices> The energy storage device 100 can be used for various purposes, but it is particularly suitable for use as a power source (driving power supply) for motors mounted on mobile vehicles (typically passenger cars, trucks, etc.). The type of vehicle is not particularly limited, but examples include plug-in hybrid electric vehicles (PHEVs), hybrid electric vehicles (HEVs), and battery electric vehicles (BEVs).

[0084] Although several embodiments of the present invention have been described above, these embodiments are merely examples. The present invention can be implemented in various other forms. The present invention can be implemented based on the contents disclosed herein and common technical knowledge in the art. The technologies described in the claims include various modifications and changes to the embodiments illustrated above. For example, it is possible to replace parts of the above embodiments with other variations, and it is also possible to add other variations to the above embodiments. Furthermore, if a technical feature is not described as essential, it may be deleted as appropriate.

[0085] (1) Spacer: For example, in the embodiment described above, the spacer 80 had a pair of long-side peripheral wall portions 81 and a pair of short-side peripheral wall portions 82 (peripheral wall portions). However, it is not limited to this. Figure 9 is a diagram corresponding to Figure 4 relating to a modified example. As shown in Figure 9, the spacer 180 of this modified example has protrusions 181 to 184 instead of peripheral wall portions. That is, the spacer 180 has a base portion 189 extending along the bottom wall 12a (first wall) and protrusions 181 to 184 provided at at least one corner of the base portion 189. The protrusions 181 to 184 can function as guides, similar to the peripheral wall portions in the embodiment. That is, in the (step 2) bending process, the base portion 189 of the spacer 180 is placed on the first portion P1 of the first plate material 12p, and the extended portion of the first plate material 12p can be bent starting from the protrusions 181 to 184. Thus, processability and workability can be improved. Furthermore, the first plate material 12p becomes less prone to bending near the bending point, making it easier to bend the extension more appropriately. In addition, in the joining process (step 3), welding can be performed with the extension parts (walls) to be joined in a stable contact state.

[0086] The protrusions 181-184 are provided on at least one corner (which may be rounded) of the base portion 189. The protrusions 181-184 are preferably made of a hard material such as metal, ceramic, or resin. They are preferably made of metal, and more preferably of aluminum or an aluminum alloy. The protrusions 181-184 are rectangular prism-shaped (block-shaped, more specifically cubic). The protrusions 181-184 are fixed (connected) to the base portion 189 and are integrated with the base portion 189.

[0087] The material and shape of the base portion 189 may be the same as those of the base portion 89 in the above-described embodiment. In some examples, the base portion 189 is made of resin and the protrusions 181-184 are made of metal. In some other examples, both the base portion 189 and the protrusions 181-184 are made of resin. The spacer 180 (base portion 189 and protrusions 181-184) may be formed by insert molding (integral molding). The spacer 180 may be pre-attached (fixed) to the first portion P1 in the first step (step 1-1).

[0088] In this embodiment, protrusions 181 to 184 are provided at each of the four corners of the base portion 189 (the four corners of the bottom wall 12a). Each of the protrusions 181 to 184 faces two adjacent side walls of the case 10. It is preferable that the protrusions 181 to 184 are in contact with the two opposing side walls after the (step 2) bending process or the (step 3) joining process. The protrusions 181 to 184 may be welded to the side walls of the case body 12 in the (step 3) joining process and integrated with the case body 12.

[0089] Furthermore, this configuration is also applicable when the terminals (positive terminal 30 and / or negative terminal 40) are not provided on the bottom wall 12a (first wall) of the case body 12, but are instead attached to the side walls of the case body 12 (long side wall 12b and / or short side wall 12c), or to the sealing plate 14 that seals the opening 12h of the case body 12.

[0090] (2) Case body: For example, in the above embodiment, in the (step 3) joining process, the joints of adjacent extension portions (walls) of the first plate material 12p were joined. However, it is not limited to this. For example, an extension portion (at least one of the second to fifth extension portions P2 to P5) may be provided with an overlapping area (overlap allowance, overlapping portion) with an adjacent extension portion. In that case, this overlapping portion may be welded to the adjacent extension portion (wall) in the (step 3) joining process. This prevents energy rays such as lasers from leaking to the electrode body 20 side when forming the welded joint 12w from hitting the electrode body 20. Also, even if spatter is scattered to the electrode body 20 side, it prevents the scattered spatter from adhering to the electrode body 20. Therefore, the electrode body 20 is less likely to be damaged.

[0091] Figure 10 is a diagram corresponding to Figure 6 relating to the first modified example. As shown in Figure 10, in this modified example, the pair of extension portions (the second and third extension portions P2 and P3 that constitute the pair of long side walls 12b) each have overlapping portions. That is, the first plate material 112p of this modified example has a second extension portion P12 and a third extension portion P13 instead of the second extension portion P2 and the third extension portion P3. The second extension portion P12 and the third extension portion P13 each have overlapping portions OL4 and OL5 that extend from the main body portion and overlap with adjacent extension portions (walls) in the (step 3) joining process, in addition to the main body portion that constitutes the pair of long side walls 12b. The overlapping portion OL4 is the portion that overlaps with the fourth extension portion P4, and the overlapping portion OL5 is the portion that overlaps with the fifth extension portion P5.

[0092] In this case, (Step 3) Before the joining process, the overlapping portions OL4 and OL5 are bent and brought into contact with the adjacent fourth extension portion P4 and fifth extension portion P5, respectively. Figure 11 is an explanatory diagram of the (Step 3) joining process according to this modified example. Figure 11 shows a magnified view of the vicinity of the overlapping portion OL5. As shown in Figure 11, in this modified example, first the overlapping portion OL5 is bent along the spacer 80. Next, for example, the overlapping portion OL5 is brought into contact with the adjacent fifth extension portion P5 so that it faces outward (towards the outer surface of the case 10), and the overlapping portion OL5 is welded together. Preferably, the overlapping portion OL5 is irradiated with an energy ray such as a laser to weld through the overlapping portion OL5. As a result, a welded joint portion 12w is formed in the overlapping portion OL5, and it is joined to the third extension portion P13 and the fifth extension portion P5. In this case, the welded joint 12w of the energy storage device 100 is formed at a position offset from the corner of the case 10 (in this case, a pair of short side walls 12c (the fourth and fifth walls)).

[0093] (3) Shape of the plate material: For example, in the embodiment described above, in the first step (step 1-1), the first plate material 12p for forming the case body 12 and the second plate material for forming the sealing plate 14 were prepared separately. However, it is not limited to this. The case 10 can also be made from a single plate material. Figures 12(A) to 12(F) are equivalent to Figure 6 relating to the second to seventh modified examples.

[0094] As shown in Figure 12(A), the plate material 210p according to the second modified example has a first portion P1 that constitutes the bottom wall 12a (first wall) of the case 10, second and third extension portions P22 and P23 that constitute a pair of long side walls 12b (second and third walls) of the case 10, and fourth and fifth extension portions P24 and P25 that constitute a pair of short side walls 12c (fourth and fifth walls) of the case 10, in addition to a sixth extension portion P26 that constitutes the top surface of the case 10 (corresponding to the sealing plate 14, sixth wall). In this modified example, the fourth and fifth extension portions P24 and P25 extend continuously from the short side of the third extension portion P3 that constitutes the long side wall 12b (third wall), respectively. The sixth extension portion P26 extends continuously from the long side of the second extension portion P2 that constitutes the long side wall 12b (second wall). The second to sixth extensions P2 to P6 are all roughly rectangular in shape. The longer sides of the second to sixth extensions P2 to P6 extend from adjacent extensions.

[0095] In this modified example, in step 2, the dashed lines are folded during the folding process, defining the first to sixth walls of case 10. In this modified example, the second to sixth extensions P22 to P26 are folded on the longer side, making them less prone to curvature during folding, thus improving processability and folding accuracy.

[0096] As shown in Figure 12(B), the plate material 310p according to the third modified example is the same as the second modified example (Figure 12(A)), except that it has fourth extension portions P34a, P34b and fifth extension portions P35a, P35b instead of fourth extension portion P24 and fifth extension portion P25. In this modified example, one short side wall 12c (fourth wall) is composed of two fourth extension portions P34a, P34b, and the other short side wall 12c (fifth wall) is composed of two fifth extension portions P35a, P35b. In this modified example, in the joining process (step 3), the joints of the two fourth extension portions P34a, P34b are joined, and the joints of the two fifth extension portions P35a, P35b are joined. As a result, a line-shaped welded joint portion 12w is formed along the vertical direction Z in the center of the short side direction X of the short side wall 12c. In this embodiment, where there are multiple electrode bodies 20 and there is a space between the electrode bodies 20 in the center of the short side direction X, this configuration can also be suitably adopted.

[0097] As shown in Figure 12(C), the plate material 410p according to the fourth modified example is the same as the embodiment described above (Figure 6), except that it has a sixth extension portion P46 that constitutes the upper surface (sixth wall) of the case 10. In this case, the sixth extension portion P46 extends continuously from the short side of the fifth extension portion P5 that constitutes the short side wall 12c (fifth wall).

[0098] As shown in Figure 12(D), the plate material 510p according to the fifth modified example is the same as the embodiment described above (Figure 6), except that it has a sixth extension portion P56 that constitutes the upper surface (sixth wall) of the case 10. In this case, the sixth extension portion P56 extends continuously from the long side of the second extension portion P2 that constitutes the long side wall 12b (second wall).

[0099] As shown in Figure 12(E), the plate material 610p according to the sixth modified example is the same as the fifth modified example (Figure 12(D)), except that the sixth extension portion P56 is replaced by sixth extension portions P66a and P66b. In this modified example, the upper surface (sixth wall) of the case 10 is composed of two sixth extension portions P66a and P66b. (Step 3) In the joining process, the joints of the two sixth extension portions P66a and P66b are joined. As a result, a line-shaped welded joint portion 12w is formed along the long side direction Y in the center of the short side direction X of the upper surface (sixth wall) of the case 10.

[0100] As shown in Figure 12(F), the plate material 710p according to the seventh modified example is the same as the first modified example (Figure 10) described above, except that it has sixth extension portions P76a and P76b that constitute the upper surface (sixth wall) of the case 10. In this modified example, the upper surface (sixth wall) of the case 10 is composed of two sixth extension portions P76a and P76b. (Step 3) In the joining process, similar to the sixth modified example, the joints of the two sixth extension portions P76a and P76b are joined, and a line-shaped welded joint 12w is formed in the center of the upper surface (sixth wall) of the case 10 in the short side direction X, along the long side direction Y.

[0101] As described above, specific embodiments of the technology disclosed herein include those described in the following sections. Item 1: A method for manufacturing an energy storage device, comprising an electrode body including a first electrode and a second electrode, a case housing the electrode body, and a first electrode terminal electrically connected to the first electrode, wherein the case is rectangular in shape and to which the first electrode terminal is attached, having a first wall partitioned by a first edge, a second edge, a third edge, and a fourth edge, a second wall extending from the first edge, a third wall extending from the second edge, a fourth wall extending from the third edge, a fifth wall extending from the fourth edge, and a sixth wall facing the first wall, and at least one of the first edge, second edge, third edge, and fourth edge being a bent portion formed by bending a member constituting the case. A method for manufacturing an energy storage device, comprising: preparing a member having a first portion that constitutes the first wall and at least one extension portion that extends from the first portion and constitutes at least one of the second wall, the third wall, the fourth wall, and the fifth wall; attaching the first electrode terminal to the first portion and electrically connecting the first electrode terminal to the first electrode; bending the extension portion after the connection step so that it is perpendicular to the first portion, thereby defining at least one of the second wall, the third wall, the fourth wall, and the fifth wall; and joining the wall defined in the bending step to an adjacent wall. Item 2: The manufacturing method according to Item 1, wherein the first edge, the second edge, the third edge, and the fourth edge are each bent portions formed by bending the members constituting the case. Item 3: The manufacturing method according to item 1 or 2, wherein in the connection step, a member is prepared having a second extension portion that constitutes the second wall, a third extension portion that constitutes the third wall, a fourth extension portion that constitutes the fourth wall, and a fifth extension portion that constitutes the fifth wall, and in the bending step, the second extension portion, the third extension portion, the fourth extension portion, and the fifth extension portion are each bent perpendicular to the first portion. Item 4: The manufacturing method according to any one of items 1 to 3, wherein a spacer is placed on the first portion before the bending step, and in the bending step, the at least one extension portion is bent along the spacer. Item 5: The manufacturing method according to Item 4, wherein the spacer comprises a base portion extending along the first portion and a peripheral wall portion protruding from the outer peripheral edge of the base portion. Item 6: The manufacturing method according to Item 5, wherein the peripheral wall portion has reinforcing ribs connecting the peripheral wall portion and the base portion. Item 7: The manufacturing method according to Item 4, wherein the spacer comprises a base portion extending along the first portion and a protrusion provided at at least one corner of the base portion. Item 8: An energy storage device comprising an electrode body including a first electrode and a second electrode, a case housing the electrode body, and a first electrode terminal electrically connected to the first electrode, wherein the case is rectangular in shape and to which the first electrode terminal is attached, having a first wall partitioned by a first edge, a second edge, a third edge, and a fourth edge, a second wall extending from the first edge, a third wall extending from the second edge, a fourth wall extending from the third edge, a fifth wall extending from the fourth edge, and a sixth wall facing the first wall, wherein at least one of the first edge, the second edge, the third edge, and the fourth edge is a bent portion formed by bending a member constituting the case. Item 9: The energy storage device according to Item 8, wherein the first edge, the second edge, the third edge, and the fourth edge are each bent portions formed by bending the members constituting the case. Item 10: The manufacturing method according to item 8 or 9, wherein the case comprises a bottomed rectangular tubular case body including the first wall, the second wall, the third wall, the fourth wall, the fifth wall, and an opening facing the first wall, and a sealing plate constituting the sixth wall and sealing the opening of the case body, wherein the outer edge of the sealing plate is welded to the periphery of the opening of the case body. Item 11: The manufacturing method according to any one of items 8 to 10, wherein in the above case, the four sides perpendicular to the first wall are welded joints formed by welding together. Item 12: The manufacturing method according to any one of items 8 to 11, further comprising a spacer between the first wall and the electrode body of the case, wherein the spacer has a base portion extending along the first wall and a peripheral wall portion protruding from the outer peripheral edge of the base portion. Item 13: The manufacturing method according to item 12, wherein the peripheral wall portion has reinforcing ribs connecting the peripheral wall portion and the base portion. Item 14: The manufacturing method according to any one of items 8 to 11, further comprising a spacer between the first wall and the electrode body of the case, wherein the spacer has a base portion extending along the first wall and a protrusion provided at at least one corner of the base portion. Item 15: The manufacturing method according to any one of items 8 to 14, wherein at least one of the first edge, second edge, third edge, and fourth edge is a thin-walled portion. Item 16: The manufacturing method according to any one of items 8 to 15, wherein at least one of the second wall, the third wall, the fourth wall, and the fifth wall has an overlapping portion that overlaps with an adjacent wall, and the overlapping portion is welded to the adjacent wall. [Explanation of symbols]

[0102] 10 cases 12 Case body 12a Bottom wall (1st wall) 12b Long side wall (2nd wall, 3rd wall) 12c Short side wall (4th wall, 5th wall) 12w welded joint 14 Sealing plate (6th wall) 20 Electrode body 30 Positive terminal 40 Negative terminal 80 Spacer 81 Long side perimeter wall 82 Short side perimeter wall 89 Base section 100 Energy storage devices 12p First board P1 Part 1 P2~P5 2nd~5th extension part

Claims

1. The device comprises an electrode body including a first electrode and a second electrode, a case for housing the electrode body, and a first electrode terminal electrically connected to the first electrode. The aforementioned case is, The first electrode terminal is attached to a first wall which is partitioned by a first edge, a second edge, a third edge, and a fourth edge, A second wall extending from the first edge, A third wall extending from the aforementioned second edge, A fourth wall extending from the aforementioned third edge, A fifth wall extending from the fourth edge, It is a rectangular shape having a sixth wall opposite the first wall, At least one of the first, second, third, and fourth edges is a bent portion formed by bending a member constituting the case. A method for manufacturing an energy storage device, A connection step is to prepare a member having a first portion that constitutes the first wall and at least one extension portion that extends from the first portion and constitutes at least one of the second wall, the third wall, the fourth wall, and the fifth wall, attach the first electrode terminal to the first portion, and connect the first electrode terminal to the first electrode electrically. After the connection step, a bending step is performed in which the extended portion is bent so that it is perpendicular to the first portion, thereby defining at least one of the second wall, the third wall, the fourth wall, and the fifth wall. A joining process is performed to join the wall defined in the aforementioned bending process to an adjacent wall, A method for manufacturing an energy storage device, including the method described above.

2. The first edge, the second edge, the third edge, and the fourth edge are each bent portions formed by bending the members that make up the case. The manufacturing method according to claim 1.

3. In the connection step, a member is prepared having a second extension portion that constitutes the second wall, a third extension portion that constitutes the third wall, a fourth extension portion that constitutes the fourth wall, and a fifth extension portion that constitutes the fifth wall, as the extension portion. In the bending process, the second extension portion, the third extension portion, the fourth extension portion, and the fifth extension portion are each bent so as to be perpendicular to the first portion. The manufacturing method according to claim 1 or 2.

4. Prior to the bending process, a spacer is placed in the first portion, In the bending step, the at least one extension is bent along the spacer. The manufacturing method according to claim 1 or 2.

5. The spacer has a base portion extending along the first portion and a peripheral wall portion protruding from the outer peripheral edge of the base portion. The manufacturing method according to claim 4.

6. The peripheral wall portion has reinforcing ribs connecting the peripheral wall portion and the base portion. The manufacturing method according to claim 5.

7. The spacer has a base portion extending along the first portion and a protrusion provided at at least one corner of the base portion. The manufacturing method according to claim 4.

8. The device comprises an electrode body including a first electrode and a second electrode, a case for housing the electrode body, and a first electrode terminal electrically connected to the first electrode. The aforementioned case is, The first electrode terminal is attached to a first wall which is partitioned by a first edge, a second edge, a third edge, and a fourth edge, A second wall extending from the first edge, A third wall extending from the aforementioned second edge, A fourth wall extending from the aforementioned third edge, A fifth wall extending from the fourth edge, It is a rectangular shape having a sixth wall opposite the first wall, At least one of the first, second, third, and fourth edges is a bent portion formed by bending a member constituting the case. Energy storage device.

9. The first edge, the second edge, the third edge, and the fourth edge are each bent portions formed by bending the members that make up the case. The energy storage device according to claim 8.

10. The aforementioned case is, A bottomed rectangular tubular case body including the first wall, the second wall, the third wall, the fourth wall, the fifth wall, and an opening facing the first wall, The sixth wall includes a sealing plate that seals the opening of the case body, The outer edge of the sealing plate is welded to the periphery of the opening of the case body. The energy storage device according to claim 8 or 9.

11. In the above case, the four sides perpendicular to the first wall are welded joints formed by welding together. The energy storage device according to claim 8 or 9.

12. A spacer is further provided between the first wall of the case and the electrode body. The spacer has a base portion extending along the first wall and a peripheral wall portion protruding from the outer peripheral edge of the base portion. The energy storage device according to claim 8 or 9.

13. The peripheral wall portion has reinforcing ribs connecting the peripheral wall portion and the base portion. The energy storage device according to claim 12.

14. A spacer is further provided between the first wall of the case and the electrode body. The spacer has a base portion extending along the first wall and a protrusion provided at at least one corner of the base portion. The energy storage device according to claim 8 or 9.

15. At least one of the first, second, third, and fourth edges is a thin-walled portion. The energy storage device according to claim 8 or 9.

16. At least one of the second wall, the third wall, the fourth wall, and the fifth wall has an overlapping portion that overlaps with an adjacent wall. The overlapping portion is welded to the adjacent wall. The energy storage device according to claim 8 or 9.

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