Manufacturing method for energy storage devices

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 assembly 20A, a case including a case body 12, a first current collector 50, and a first electrode terminal 30, wherein the first electrode terminal 30 is provided on the bottom wall 12a of the case body 12. This manufacturing method includes a placement step of placing at least a portion 210 of a pressing jig 200 inside the electrode assembly 20A, an insertion step of inserting the electrode assembly 20A inside the case body 12, and a joining step of joining the first electrode terminal 30 and the first current collector 50 after the insertion step, with the first current collector 50 pressed against the first electrode terminal 30 by the pressing jig 200 placed inside the electrode assembly 20A.

Description

Technical Field

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

Background Art

[0002] Patent Document 1 discloses a power storage device including 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 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

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, it is difficult to stably abut both members in the case when joining the electrode tab and the first electrode terminal, and there is a problem that the difficulty of joining increases. 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 assembly having one or more electrode bodies including a first electrode and a second electrode; a case for housing the electrode body assembly; a first current collector member electrically connected to the first electrode within the case; and a first electrode terminal electrically connected to the first current collector member, wherein the case comprises a bottomed cylindrical case body having a bottom wall, a side wall provided on the outer peripheral edge of the bottom wall, and an opening facing the bottom wall; and a sealing plate for sealing the opening of the case body, with the first electrode terminal provided on the bottom wall of the case body. This manufacturing method includes a placement step of placing at least a portion of a pressing jig inside the electrode assembly, an insertion step of inserting the electrode assembly inside the case body, and a joining step of joining the first electrode terminal and the first current collector member after the insertion step, with the first current collector member pressed against the first electrode terminal by the pressing jig placed inside the electrode assembly.

[0007] According to the above manufacturing method, in the joining process, the first electrode terminal and the first current collector can be joined while being precisely brought into contact with each other by a pressing jig. This makes it possible to stably form a conductive path with high conductivity. 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 cross-sectional view along the line III-III in Figure 1. [Figure 4] Figure 4 is a schematic diagram showing the configuration of the electrode body. [Figure 5] Figure 5 is a schematic plan view showing the first current collector. [Figure 6] Figure 6 is a plan view illustrating the merging process. [Figure 7]Figure 7 is a schematic perspective view showing a pressing jig according to one embodiment. [Figure 8] Figure 8 is a plan view illustrating the lamination process. [Figure 9] Figure 9 is a schematic perspective view showing the combined object. [Figure 10] Figure 10 is an explanatory diagram of the insertion process. [Figure 11] Figure 11 is a schematic longitudinal cross-sectional view of the positive electrode side of the second composite structure. [Figure 12] Figure 12 is an explanatory diagram of the joining process. [Figure 13] Figure 13 is a magnified view of the vicinity of the positive terminal in a modified example. [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] First, we will describe the energy storage devices manufactured by the manufacturing methods disclosed herein. In this specification, "energy storage device" refers to any device that can be repeatedly charged and discharged by 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 secondary batteries such as lithium-ion secondary batteries and nickel-metal hydride secondary batteries, as well as capacitors that utilize chemical reactions, such as lithium-ion capacitors and pseudocapacitance capacitors.

[0011] 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 transverse 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 vertical direction of the power storage device 100. The vertical 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.

[0012] As shown in Figure 2, the energy storage device 100 comprises a case 10, an electrode assembly 20A, a positive electrode terminal 30, a negative electrode terminal 40, a positive electrode current collector 50, and a negative electrode current collector 60. The energy storage device 100 further comprises a spacer 80 and a liquid electrolyte (electrolyte, not shown). However, the spacer 80 is 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] Case 10 is a housing for an electrode assembly 20A containing one or more electrode bodies 20. As shown in Figure 1, case 10 has a flattened, bottomed rectangular parallelepiped (square) shape. The material of case 10 can be the same as that conventionally used, and there are no particular restrictions. Case 10 is preferably made of metal, and more preferably of aluminum, aluminum alloy, iron, iron alloy, etc. As shown in Figure 2, case 10 comprises a case body 12 and a sealing plate (lid) 14. Case 10 (case body 12 and sealing plate 14) has a size that corresponds to the size of the electrode bodies 20 and the number of electrodes it houses (one or more).

[0014] The case body 12 is a bottomed cylindrical shape having a bottom wall, side walls provided at the outer peripheral edge of the bottom wall, and an opening facing the bottom wall. Here, the case body 12 is a bottomed and rectangular container having an opening 12h on the upper surface. Specifically, as shown in FIG. 1, the case body 12 is a bottomed rectangular tube shape, and has a substantially rectangular bottom wall 12a (first wall) having long sides and short sides, a pair of long side walls 12b (second wall and third wall) extending from the long sides of the bottom wall 12a and facing each other, a pair of short side walls 12c (fourth wall and fifth wall) extending from the short sides of the bottom wall 12a and facing each other, and an opening 12h (see FIG. 2) facing the bottom wall 12a. The case body 12 is preferably a bottomed rectangular tube shape. The opening 12h is substantially rectangular here. The bottom wall 12a constitutes the lower surface of the case 10.

[0015] In addition, in this specification, the term "substantially rectangular shape" 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 long side wall 12b has a larger area than the short side wall 12c. In the present embodiment, the long side wall 12b and the short side wall 12c are each continuously formed from the outer peripheral edge of the bottom wall 12a. In other words, the boundary portion between the bottom wall 12a and the long side wall 12b is not a welded portion (not welded and joined), but a bent portion. Similarly, the boundary portion between the bottom wall 12a and the short side wall 12c is not a welded portion (not welded and joined), but a bent portion. The case body 12 having such a shape can be formed, for example, by deep drawing a single metal plate. The long side wall 12b and the short side wall 12c are an example of the "side wall".

[0017] 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 of the case body 12. The sealing plate 14 is substantially rectangular in this case. The sealing plate 14 constitutes the top surface of the case 10. The case 10 is integrated by joining (e.g., welding) the sealing plate 14 to the periphery of the opening 12h of the case body 12. As shown in Figure 2, a joint (e.g., a welded joint) 10w is formed at the fitting portion between the case body 12 and the sealing plate 14. This seals (airtightly seals) the case 10.

[0018] As shown in Figures 1 and 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 electrolyte injection hole 15 may also be provided on the sealing plate 14. 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 gas discharge valve 17 may also be provided on the sealing plate 14. 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 terminal 30 and the negative terminal 40 are inserted through the terminal exit holes 18 and 19 of the bottom wall 12a, respectively.

[0019] The electrode assembly 20A is housed inside the case 10. The electrode assembly 20A includes one or more electrode bodies 20. The number of electrode bodies 20 is not particularly limited and may be one or multiple (e.g., two or more, three or more). As shown in Figure 3, the electrode assembly 20A here includes two electrode bodies 20. That is, the electrode assembly 20A includes a first electrode body 20 and a second electrode body 20.

[0020] As shown in Figures 2 and 3, the electrode assembly 20A is placed inside the case 10, covered by an electrode holder 29 made of a resin sheet. This prevents the electrode 20 from coming into direct contact with the case body 12. The material of the electrode holder 29 can be the same as that used conventionally, 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).

[0021] Figure 4 is a schematic diagram showing the configuration of one electrode body 20. In Figure 4, the symbol LD indicates the longitudinal direction of the electrode body 20, which is manufactured in a strip shape. The symbol WD is a direction approximately perpendicular to the longitudinal direction LD and indicates the winding axis direction of the electrode body 20.

[0022] As shown in Figure 4, the electrode body 20 includes a positive electrode 22 and a negative electrode 24. In this embodiment, the electrode body 20 is a wound electrode body constructed by stacking a strip-shaped positive electrode 22 and a strip-shaped negative electrode 24 insulated from two strip-shaped separators 26, and winding them in the longitudinal direction LD around a winding axis WL. However, the electrode body 20 may also be a laminated electrode body in which multiple rectangular positive electrodes and multiple rectangular negative electrodes are stacked in an insulated state. One of the positive electrode 22 and the negative electrode 24 is an example of a "first electrode," and the other is an example of a "second electrode."

[0023] The electrode body 20 here has a flattened shape. As shown in Figure 3, 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 WD is substantially the same as the vertical direction Z. The pair of curved portions 20r here face a pair of short side walls 12c of the case body 12. The pair of flat portions 20f here face a long side wall 12b of the case body 12. The end faces of the electrode body 20 (i.e., the laminated surface where the positive electrode 22 and the negative electrode 24 are stacked, both ends of the winding axis direction WD in Figure 4) face the bottom wall 12a and the sealing plate 14.

[0024] As shown in Figure 4, the positive electrode 22 comprises a strip-shaped positive electrode current collector 22c and a positive electrode active material layer 22a fixed to at least one surface (preferably both sides) of the positive electrode current collector 22c. The positive electrode 22 here further comprises a positive electrode protective layer 22p. However, the positive electrode protective layer 22p is not essential and can be omitted in other embodiments. The components constituting the positive electrode 22 can be made of conventionally known materials that can be used in general energy storage devices (e.g., lithium-ion secondary batteries) without particular limitation. The positive electrode current collector 22c is preferably made of a conductive metal such as aluminum, aluminum alloy, nickel, or stainless steel, and here it is a metal foil, specifically aluminum foil. However, as described in the modified example (1-1) below, the positive electrode current collector 22c may have an insulating core (e.g., a resin layer).

[0025] As shown in Figure 4, the positive electrode 22 has a plurality of positive electrode tabs 22t on one end side in the winding axis direction WD. The plurality of positive electrode tabs 22t are provided at predetermined intervals (intermittently) along the longitudinal direction LD. Each of the plurality of positive electrode tabs 22t is convex and protrudes outward (to the left in Figure 4). The plurality of positive electrode tabs 22t are identical in shape and are each approximately rectangular. The width of the positive electrode tabs 22t (length of the longitudinal direction LD) is preferably about 15 mm or more, for example, 20 to 40 mm. However, the plurality of positive electrode tabs 22t may differ in size and shape from one another. The positive electrode tabs 22t are provided integrally with the positive electrode 22. The positive electrode tabs 22t are regions in the positive electrode current collector 22c where the positive electrode active material layer 22a is not formed. The positive electrode current collector 22c is exposed in at least a portion of the positive electrode tabs 22t. However, as described in the modified example (1-2) below, the positive electrode tab 22t may be a different component from the positive electrode 22.

[0026] Multiple positive electrode tabs 22t are stacked at one end of the electrode body 20 in the winding axis direction WD, forming a group of positive electrode tabs 27 (see Figure 2). As shown in Figure 2, the tip of the group of positive electrode tabs 27 (the lower end in Figure 2) is connected (more specifically, joined) to the positive electrode current collector 50. The positive electrode 22 is electrically connected to the positive electrode terminal 30 via the group of positive electrode tabs 27 (multiple positive electrode tabs 22t) and the positive electrode current collector 50.

[0027] As shown in Figure 4, the positive electrode active material layer 22a is provided in a strip shape along the longitudinal direction LD of the positive electrode current collector 22c. The positive electrode active material layer 22a contains a positive electrode active material (for example, a lithium transition metal composite oxide such as lithium nickel cobalt manganese composite oxide) that can reversibly intercept and release charge carriers. The positive electrode active material layer 22a may also contain optional components other than the positive electrode active material, such as conductive materials, binders, and various additives.

[0028] As shown in Figure 4, the positive electrode protective layer 22p is provided in a strip shape along the longitudinal direction LD of the positive electrode current collector 22c. The positive electrode protective layer 22p is provided at the boundary between the positive electrode current collector 22c and the positive electrode active material layer 22a in the winding axis direction WD. The positive electrode protective layer 22p contains an insulating inorganic filler (for example, ceramic particles such as alumina). The positive electrode protective layer 22p may also contain optional components other than the inorganic filler, such as a binder, conductive material, various additives, etc. By providing the positive electrode protective layer 22p, it is possible to prevent the positive electrode 22 from directly contacting the negative electrode active material layer 24a and causing an internal short circuit in the energy storage device 100 when the separator 26 is damaged.

[0029] As shown in Figure 4, the negative electrode 24 comprises a strip-shaped negative electrode current collector 24c and a negative electrode active material layer 24a fixed to at least one surface (preferably both sides) of the negative electrode current collector 24c. The components constituting the negative electrode 24 can be made of conventionally known materials that can be used in general energy storage devices (e.g., lithium-ion secondary batteries) without particular limitations. The negative electrode current collector 24c is preferably made of a conductive metal such as copper, copper alloy, nickel, or stainless steel, and in this case, a metal foil, specifically a copper foil. However, as described in the modified example (1-1) below, the negative electrode current collector 24c may have an insulating core (e.g., a resin layer).

[0030] As shown in Figure 4, the negative electrode 24 has multiple negative electrode tabs 24t on one end in the winding axis direction WD. In the winding axis direction WD, the negative electrode tabs 24t are provided on the same side (left side in Figure 4) as the positive electrode tabs 22t. The multiple negative electrode tabs 24t are provided at predetermined intervals (intermittently) along the longitudinal direction LD. Each of the multiple negative electrode tabs 24t is convex and protrudes outward (left side in Figure 4). The multiple negative electrode tabs 24t are identical in shape and are approximately rectangular. The width of the negative electrode tabs 24t (length of the longitudinal direction LD) is generally 15 mm or more, for example, 20 to 40 mm. However, the multiple negative electrode tabs 24t may differ in size and shape from one another. The negative electrode tabs 24t are provided integrally with the negative electrode 24 in this case. The negative electrode tab 24t is a region in the negative electrode current collector 24c where the negative electrode active material layer 24a is not formed. At least a portion of the negative electrode tab 24t exposes the negative electrode current collector 24c. However, as described in the modified example (1-2) below, the negative electrode tab 24t may be a separate component from the negative electrode 24.

[0031] Multiple negative electrode tabs 24t are stacked at one end of the electrode body 20 in the winding axis direction WD, forming a negative electrode tab group 28 (see Figure 2). As shown in Figure 2, the tip of the negative electrode tab group 28 (lower end in Figure 2) is connected (more specifically, joined) to the negative electrode current collector 60. The negative electrode 24 is electrically connected to the negative electrode terminal 40 via the negative electrode tab group 28 (multiple negative electrode tabs 24t) and the negative electrode current collector 60.

[0032] As shown in Figure 4, the negative electrode active material layer 24a is provided in a strip shape along the longitudinal direction LD of the negative electrode current collector 24c. The negative electrode active material layer 24a contains a negative electrode active material (for example, a carbon material such as graphite, or a silicon material) that can reversibly absorb and release charge carriers. The negative electrode active material layer 24a may also contain optional components other than the negative electrode active material, such as a binder, a dispersant, or various additives.

[0033] As shown in Figure 4, the separator 26 is a component that insulates the positive electrode active material layer 22a of the positive electrode 22 and the negative electrode active material layer 24a of the negative electrode 24. For the separator 26, a porous sheet made of polyolefin resin such as polyethylene (PE) or polypropylene (PP) is preferred. The separator 26 may have a base material made of a porous sheet made of resin and a functional layer (for example, a heat-resistant layer (HRL) or adhesive layer) formed on at least one surface of the base material. The heat-resistant layer is typically a layer containing an inorganic filler and a binder. Examples of inorganic fillers include alumina, boehmite, aluminum hydroxide, and titania. Here, the separator 26 constitutes the outer surface (outermost periphery) of the electrode body 20.

[0034] 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.

[0035] As shown in Figures 1 and 2, the positive terminal 30 and the negative terminal 40 are each attached to the bottom wall 12a of the bottomed cylindrical case body 12. 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 22 is the "first electrode", the positive terminal 30 is an example of the "first electrode terminal", and the negative terminal 40 is an example of the "second electrode terminal". When the negative electrode 24 is the "first electrode", the negative terminal 40 is an example of the "first electrode terminal", and the positive terminal 30 is an example of the "second electrode terminal".

[0036] In case 10, the terminals (positive terminal 30 and / or negative terminal 40) are provided on the side opposite to the 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 joint 10w, it is possible to suppress a large load on the joint 10w even if an external force is applied to the terminals when the energy storage device 100 is in use. Therefore, the joint 10w becomes less susceptible to damage, and the sealing performance and reliability of the joint 10w can be improved.

[0037] As shown in Figures 1 and 2, the terminals (positive terminal 30 and / or negative terminal 40) are insulated from the bottom wall 12a of the case body 12 by an insulating member (in this case, a gasket 90). The terminals are fixed to the bottom wall 12a of the case body 12 via the gasket 90. The gasket 90 is preferably made of resin. The terminals may also be attached to the bottom wall 12a together with the gasket 90 by insert molding (integral molding). This increases the adhesion between the terminals, the gasket 90 and the bottom wall 12a, improving sealing performance and reliability. However, in other embodiments, the terminals may be fixed to the bottom wall 12a together with the gasket 90 by crimping or the like, or fixed to the bottom wall 12a via an adhesive layer (adhesive, etc.). Also, if the bottom wall 12a serves as one of the terminals, one of the terminals may be electrically connected to the bottom wall 12a directly or via another conductive member.

[0038] As shown in Figure 2, the positive electrode terminal 30 is inserted through a terminal lead-out hole 18 in the bottom wall 12a and extends from the inside to the outside of the case body 12. A portion of the positive electrode terminal 30 protrudes from the terminal lead-out hole 18 to the outer surface of the bottom wall 12a and is exposed to the outside of the case 10. Inside the case 10, the positive electrode terminal 30 is electrically connected to the positive electrode 22 of the electrode body 20. The positive electrode terminal 30 is electrically connected to the positive electrode 22 of the electrode body 20 via a positive electrode current collector 50 and a group of positive electrode tabs 27 (multiple positive electrode tabs 22t). The positive electrode terminal 30 is preferably made of metal, and more preferably of aluminum or an aluminum alloy. The positive electrode terminal 30 has a through hole 30h provided along the terminal lead-out hole 18. The through hole 30h is formed in a cylindrical shape. The positive electrode current collector 50 (specifically the second connecting part 52), which will be described later, is inserted through the through hole 30h.

[0039] As shown in Figure 2, the negative electrode terminal 40 is inserted through a terminal lead-out hole 19 in the bottom wall 12a and extends from the inside to the outside of the case body 12. A portion of the negative electrode terminal 40 protrudes from the terminal lead-out hole 19 towards the outer surface of the bottom wall 12a and is exposed to the outside of the case 10. Inside the case 10, the negative electrode terminal 40 is electrically connected to the negative electrode 24 of the electrode body 20. Here, the negative electrode terminal 40 is electrically connected to the negative electrode 24 of the electrode body 20 via a negative electrode current collector 60 and a group of negative electrode tabs 28 (a plurality of negative electrode tabs 24t). The negative electrode terminal 40 is preferably made of metal, and more preferably of copper or a copper alloy. The negative electrode terminal 40 has a through hole 40h provided along the terminal lead-out hole 19. Here, the through hole 40h is formed in a cylindrical shape.

[0040] The positive electrode current collector 50 is a conductive member and, as shown in Figure 2, constitutes a conductive path between the positive electrode 22 (specifically the group of positive electrode tabs 27) and the positive electrode terminal 30. By interposing the positive electrode current collector 50 between the group of positive electrode tabs 27 and the positive electrode terminal 30, the electrical connection can be made more stable. The positive electrode current collector 50 is preferably made of a metal with excellent conductivity, such as aluminum or an aluminum alloy. The positive electrode current collector 50 may also be made of the same type of metal as the positive electrode tabs 22t and / or the positive electrode terminal 30. The positive electrode current collector 50 has a first connection part 51 and a second connection part 52. When the positive electrode 22 is the "first electrode", the positive electrode current collector 50 is an example of the "first current collector", and the negative electrode current collector 60 is an example of the "second current collector".

[0041] The first connector 51 is attached to the positive electrode tab group 27 (multiple positive electrode tabs 22t) and is electrically connected to the positive electrode 22. The first connector 51 is joined to the positive electrode tab group 27 (for example, by welding such as ultrasonic welding). The first connector 51 is flat and extends along the inner surface of the bottom wall 12a. In the long side direction Y, the width of the first connector 51 is wider than the width of the positive electrode tab group 27. The second connector 52 is inserted through the through hole 30h of the positive electrode terminal 30. The second connector 52 is columnar, specifically cylindrical. The lower end surface of the second connector 52 is substantially flush with the lower end surface (outer side) of the positive electrode terminal 30 (allowing for manufacturing tolerances, etc.). The second connector 52 is joined to the positive electrode terminal 30 on the outside of the case body 12 (outer surface side of the bottom wall 12a).

[0042] A joint J between the positive electrode terminal 30 and the positive electrode current collector 50 is formed on the outer side of the case body 12. Preferably, the joint J is a welded joint formed by irradiation with an energy ray, such as laser welding. In this case, the joint J protrudes outside the through hole 30h. As shown in Figure 1, the joint J is annular (for example, circular). The joint J is continuously provided around the entire circumference at the boundary between the periphery of the through hole 30h of the positive electrode terminal 30 and the second connection portion 52 of the positive electrode current collector 50. This makes it easier to maintain a more stable electrical connection between the positive electrode terminal 30 and the positive electrode current collector 50, and improves the conductivity reliability of the joint J.

[0043] The negative electrode current collector 60 is a conductive member and, as shown in Figure 2, constitutes a conductive path between the negative electrode 24 (specifically the negative electrode tab group 28) and the negative electrode terminal 40. By interposing the negative electrode current collector 60 between the negative electrode tab group 28 and the negative electrode terminal 40, it becomes easier to maintain a more stable electrical connection. The negative electrode current collector 60 is preferably made of a metal with excellent conductivity, such as copper or a copper alloy. The negative electrode current collector 60 may also be made of the same type of metal as the negative electrode tab 24t and / or the negative electrode terminal 40. The negative electrode current collector 60 has the same configuration as the positive electrode current collector 50. The negative electrode current collector 60 has a first connection part 61 and a second connection part 62. When the negative electrode 24 is the "first electrode", the negative electrode current collector 60 is an example of the "first current collector", and the positive electrode current collector 50 is an example of the "second current collector".

[0044] The first connection portion 61 is attached to the negative electrode tab group 28 (a plurality of negative electrode tabs 24t) and is electrically connected to the negative electrode 24. The first connection portion 61 is joined to the negative electrode tab group 28 (for example, by welding such as ultrasonic welding). The first connection portion 61 is flat in shape and extends along the inner surface of the bottom wall 12a. In the long side direction Y, the width of the first connection portion 61 is wider than the width of the negative electrode tab group 28. The second connection portion 62 is inserted through the through hole 40h of the negative electrode terminal 40. The second connection portion 62 is columnar, specifically cylindrical in shape. The lower end surface of the second connection portion 62 is substantially flush with the lower end surface (outer surface) of the negative electrode terminal 40. The second connection portion 62 is joined to the negative electrode terminal 40 on the outside of the case body 12 (on the outer surface side of the bottom wall 12a).

[0045] On the exterior side of the case body 12, a joint J is formed between the negative terminal 40 and the negative current collector 60, similar to the positive terminal side. Here, the joint J protrudes outside the through hole 40h. As shown in Figure 1, the joint J here is annular (for example, circular).

[0046] As shown in Figure 2, the spacer 80 is positioned inside the case 10, between the bottom wall 12a and the electrode body 20. The spacer 80 is typically insulating and preferably made of resin. The material of the spacer 80 may be the same as that exemplified for the material of the electrode body holder 29. The spacer 80 has a flat base portion 80b and a plurality of protrusions 80p that project from the base portion 80b toward the bottom wall 12a. The base portion 80b is provided along the end face of the electrode body 20. The plurality of protrusions 80p are each provided at a distance from the terminals (positive terminal 30 and / or negative terminal 40). In this case, there are four protrusions 80p (number of terminals × 2). The presence of the protrusions 80p ensures that when the bottom wall 12a of the case body 12 is positioned vertically downward during the manufacture or use of the energy storage device 100, the weight of the electrode body 20 is supported by the protrusions 80p. Therefore, damage to the conductive path due to the weight of the electrode body 20 can be effectively suppressed.

[0047] [Manufacturing method for energy storage devices] The energy storage device 100 can be manufactured by a method including, for example, the following steps: (Step 1) placement step; (Step 2) insertion step; (Step 3) joining step; (Step 4) removal step; (Step 5) sealing step. In this embodiment, the case in which (Step 2) insertion step is performed after (Step 1) placement step is described. However, as will be described in the modified example (5) below, the order of (Step 1) placement step and (Step 2) insertion step is not particularly limited and may be reversed or performed almost simultaneously. Also, (Step 4) removal step is not mandatory and may be omitted. Furthermore, the manufacturing method disclosed herein may include other steps at any stage. For example, after (Step 5) sealing step, a step of pouring electrolyte into the case 10 may be included.

[0048] (Step 1) In the placement step, the pressing jig 200 (see Figure 7) is placed inside the electrode assembly 20A. In this embodiment, the placement step includes a preparation step (Step 1A), a combination step (Step 1B), and a lamination step (Step 1C) in that order. Figure 6 is a plan view illustrating the combination step (Step 1B), and Figure 8 is a plan view illustrating the lamination step (Step 1C).

[0049] In the preparation step (step 1A), 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 this embodiment, two wound electrode bodies as shown in Figure 4 are prepared. That is, a first electrode body 20 and a second electrode body 20 are prepared.

[0050] A wound electrode body can be manufactured, for example, as follows. First, a strip-shaped positive electrode 22 and a strip-shaped negative electrode 24 are stacked via a strip-shaped separator 26, and then wound around an axis with a winding axis WL as the center to form a cylindrical shape. At this time, multiple positive electrode tabs 22t and multiple negative electrode tabs 24t are adjusted so that they protrude from the same end and are stacked at different positions. Next, a flat-shaped electrode body 20 is manufactured by, for example, press-molding the wound cylindrical electrode body (cylindrical body) into a flat shape. Then, multiple positive electrode tabs 22t are bundled together, preferably by joining the positive electrode tabs 22t together to form a group of positive electrode tabs 27. Similarly, multiple negative electrode tabs 24t are bundled together, preferably by joining the negative electrode tabs 24t together to form a group of negative electrode tabs 28.

[0051] In this way, a first electrode body 20 and a second electrode body 20 are prepared. The first electrode body 20 has a first electrode tab group including a plurality of first electrode tabs (positive electrode tabs 22t or negative electrode tabs 24t), and the second electrode body 20 has a second electrode tab group including a plurality of second electrode tabs (positive electrode tabs 22t or negative electrode tabs 24t). The first and second electrode bodies 20 each have a positive electrode tab group 27 including a plurality of positive electrode tabs 22t and a negative electrode tab group 28 including a plurality of negative electrode tabs 24t. The outer surfaces of the first and second electrode bodies 20 are each covered with a separator 26.

[0052] In the joining process (step 1B), the first electrode tab group of the first electrode body 20 and the second electrode tab group of the second electrode body 20 (typically an electrode tab group with the same polarity as the first electrode tab group) are joined to one first current collector to produce a combined product 300 (see Figure 9). In this embodiment, the positive electrode tab group 27 (first electrode tab group) of the first electrode body 20 and the positive electrode tab group 27 (second electrode tab group) of the second electrode body 20 are joined to one positive electrode current collector 50 (first current collector), and the negative electrode tab group 28 of the first electrode body 20 and the negative electrode tab group 28 of the second electrode body 20 are joined to one negative electrode current collector 60. Specifically, first, one positive electrode current collector 50 and one negative electrode current collector 60 are prepared.

[0053] Figure 5 is a schematic plan view showing the first connection portion 51 of the positive electrode current collector 50. Here, the side facing the electrode body 20 in the state of the energy storage device 100 is shown. As shown in Figure 5, the first connection portion 51 of the positive electrode current collector 50 has a roughly rectangular shape. The first connection portion 51 of the positive electrode current collector 50 has a first region A1 to which the first electrode tab group is connected, a second region A2 to which the second electrode tab group is connected, and a recess 51r provided between the first region A1 and the second region A2 on the side facing the electrode body 20. The recess 51r extends along the long side direction Y. The recess 51r is the part into which a part of the pressing jig 200 (specifically, the tip portion 210t of the first projection 210 described later) is fitted during the lamination process (step 1C) described later. Note that the negative electrode current collector 60 has the same configuration as the positive electrode current collector 50.

[0054] Next, as shown in Figure 6, a positive electrode current collector 50 is placed between the first electrode body 20 and the second electrode body 20, the positive electrode tab group 27 of the first electrode body 20 is joined to the first region A1 of the positive electrode current collector 50, and the positive electrode tab group 27 of the second electrode body 20 is joined to the second region A2 of the positive electrode current collector 50. This forms a joint J1 between the positive electrode tab group 27 and the positive electrode current collector 50. In this embodiment, similarly on the negative electrode side, the negative electrode tab group 28 of the first electrode body 20 is joined to the first region of the negative electrode current collector 60, and the negative electrode tab group 28 of the second electrode body 20 is joined to the second region of the negative electrode current collector 60. This forms a joint J1 between the negative electrode tab group 28 and the negative electrode current collector 60. The joining method is not particularly limited, but in some embodiments, it is preferable to join by welding such as ultrasonic welding, resistance welding, or laser welding.

[0055] In the lamination process (step 1C), after the joining process, the first electrode body 20 and the second electrode body 20 are superimposed so that a pressing jig 200 is positioned between the first electrode body 20 and the second electrode body 20. In this embodiment, first, the pressing jig 200 is prepared. Figure 7 is a schematic perspective view of the pressing jig 200. The pressing jig 200 is preferably insulating. This prevents short circuits from occurring even if, for example, a part of the pressing jig 200 is chipped or scraped off during operation and remains inside the electrode body assembly 20A. The pressing jig 200 is preferably made of resin, and more preferably made of polyolefin resins such as polypropylene (PP) or polyethylene (PE), perfluoroalkoxyalkanes, or fluororesins such as polytetrafluoroethylene (PTFE). As shown in Figure 7, the pressing jig 200 has a support portion 290, a first projection 210, a second projection 220, a rib 230, and a recess 290r. The symbol VD represents the vertical direction.

[0056] The support portion 290 is the part that supports the end face of the electrode assembly 20A. More specifically, the end face of the electrode assembly 20A on the rear side in the insertion direction during the insertion process described later (Step 2), in other words, the end face on the side away from the first current collector (positive electrode current collector 50 and / or negative electrode current collector 60), is placed on the support portion 290. The support portion 290 extends along the XY plane. The support portion 290 is flat. In the long side direction Y, the length of the support portion 290 is approximately the same as (within ±1 cm) as the end face of the electrode assembly 20A described above. In an XY plane view, the area of ​​the support portion 290 is preferably the same as or larger than the end face of the electrode assembly 20A. The area of ​​the support portion 290 is preferably the same as or larger than the cross-sectional area of ​​the opening 12h of the case body 12. The presence of the support portion 290 allows the electrode assembly 20A to be stably inserted into the case body 12 during the insertion process described later. Furthermore, damage to the end faces of the electrode 20 can be suppressed.

[0057] As shown in Figure 7, the first protrusion 210 protrudes vertically in the direction VD from the support portion 290. The first protrusion 210 is positioned to contact the positive electrode current collector 50 when the pressing jig 200 is placed inside the electrode body assembly 20A. The tip portion 210t of the first protrusion 210 contacts the positive electrode current collector 50 in the lamination process (step 1C) described later and is fitted into the recess 51r. Preferably, the tip portion 210t of the first protrusion 210 has a rounded corner (R shape). This prevents damage to the electrode body 20 and peeling of the separator 26 constituting the outer surface of the electrode body 20 when inserting the pressing jig 200 inside the electrode body assembly 20A or when removing the pressing jig 200 from the electrode body assembly 20A in the removal process (step 4).

[0058] As shown in Figure 8, in some embodiments, when the protrusion height of the first protrusion 210 (see also Figure 7) is T1 and the height of the electrode body 20 (height of the main body excluding the positive electrode tab group 27 and the negative electrode tab group 28, length WD in the winding axis direction of the separator 26, see also Figure 4) is T2, it is preferable that T1 ≥ T2, and more preferably that T1 > T2. This makes it easier to stably bring the positive electrode current collector member 50 into contact with the positive electrode terminal 30 in the bonding process (step 3) described later.

[0059] Furthermore, in some embodiments, when the width of the tip portion 210t of the first projection 210 (length in the long side direction Y, see also Figure 7) is W1, and the width of the recess 51r of the positive electrode current collector member 50 (the portion that contacts the pressing jig 200, see also Figure 5) is W2, it is preferable that W1 ≥ W2, and more preferably that W1 > W2. This allows the positive electrode current collector member 50 and the pressing jig 200 to be stably brought into contact when the positive electrode current collector member 50 is pressed in the joining process (step 3) described later.

[0060] As shown in Figure 7, the second protrusion 220 protrudes vertically in the direction VD from the support portion 290. The second protrusion 220 protrudes on the same side as the first protrusion 210. The second protrusion 220 is positioned to contact the negative electrode current collector 60 when the pressing jig 200 is placed inside the electrode assembly 20A. The second protrusion 220 has the same configuration as the first protrusion 210. The protrusion height and width of the second protrusion 220 are the same as those of the first protrusion 210. The tip portion 220t of the second protrusion 220 contacts the negative electrode current collector 60 in the lamination process (step 1C) described later and is fitted into the recess 61r (see Figure 8).

[0061] As shown in Figure 7, there are multiple ribs 230, each provided along a pair of ends of the support portion 290 in the short-side direction X. Each pair of ribs 230 extends along the support portion 290 in the long-side direction Y. The pair of ribs 230 sandwich the support portion 290 from both sides in the short-side direction X. In the short-side direction X, the distance between the pair of ribs 230 is the same as or longer than the length of the case body 12 in the short-side direction X. This ensures that when the electrode assembly 20A is inserted into the case body 12 during the insertion process (Step 2) described later, the case body 12 is positioned between the pair of ribs 230. Each pair of ribs 230 faces the outer surface of the side wall of the case body 12 (specifically, the pair of long side walls 12b). That is, the pair of ribs 230 can function as positioning parts that determine the position of the pressing jig 200 relative to the case body 12 in the short-side direction X.

[0062] The recesses 290r are provided in the support portion 290, as shown in Figure 7. The recesses 290r are provided on the same surface as the first protrusions 210 and the second protrusions 220 of the support portion 290. The recesses 290r are provided on the surface facing the electrode assembly 20A in the lamination process (step 1C) described later. There are multiple recesses 290r, each provided at the boundary between the support portion 290 and the pair of ribs 230. The recesses 290r each extend in the long side direction Y. When an insulating sheet for forming the electrode holder 29 is placed around the electrode assembly 20A after the lamination process (step 1C), a portion of the insulating sheet (the portion longer than the side surface of the electrode assembly 20A, which is folded after the bonding process) is accommodated in the recesses 290r. In other words, the recesses 290r are portions for accommodating the insulating sheet.

[0063] As shown in Figure 7, the pressing jig 200 is a single component, and the length of the support portion 290 in the long side direction Y is approximately the same as the end face of the electrode assembly 20A. The pressing jig 200 also has a first projection 210 and a second projection 220, and is configured to contact the positive electrode current collector 50 and the negative electrode current collector 60 (first current collector and second current collector). However, the pressing jig 200 may be composed of multiple components, for example, arranged at spaced-apart positions. For example, it may be composed of a first component having a first projection 210 that contacts the positive electrode current collector 50, and a second component having a second projection 220 that contacts the negative electrode current collector 60.

[0064] Next, as shown in Figure 8, the pressing jig 200 is positioned so as to overlap one of the electrode bodies 20, and the first projection 210 of the pressing jig 200 is brought into contact with the positive electrode current collector 50, with the tip portion 210t fitted into the recess 51r. Similarly, the second projection 220 of the pressing jig 200 is brought into contact with the negative electrode current collector 60, with the tip portion 220t fitted into the recess 61r. Then, as indicated by the arrows in Figure 8, the pressing jig 200 is lifted vertically while the tip portion 210t of the first projection 210 of the pressing jig 200 presses the positive electrode current collector 50 and the tip portion 220t of the second projection 220 presses the negative electrode current collector 60. As a result, the first protrusion 210 and the second protrusion 220 of the pressing jig 200 are sandwiched between the first electrode body 20 and the second electrode body 20. This method makes it easier to stably position the pressing jig 200 between the first electrode body 20 and the second electrode body 20, thereby improving work efficiency. Furthermore, damage to the electrode body 20 can be effectively suppressed.

[0065] Figure 9 is a schematic perspective view of the combined object 300. As shown in Figure 9, the combined object 300 includes an electrode assembly 20A (a first electrode body 20 and a second electrode body 20) and a pressing jig 200. In the combined object 300, the electrode assembly 20A is supported by a support portion 290 of the pressing jig 200. The electrode assembly 20A is positioned between a pair of ribs 230 of the pressing jig 200. At least a portion of the pressing jig 200 (here, a first projection 210 and a second projection 220) is positioned between the first electrode body 20 and the second electrode body 20. Furthermore, the portion of the first electrode body 20 that the pressing jig 200 contacts is a separator 26, and the portion of the second electrode body 20 that the pressing jig 200 contacts is also a separator 26. This effectively suppresses damage to the electrode body 20. More specifically, it suppresses damage to the active material layers (positive electrode active material layer 22a and / or negative electrode active material layer 24a) provided on the electrodes (positive electrode 22 and / or negative electrode 24).

[0066] In this embodiment, an insulating sheet is then placed around the electrode assembly 20A. This insulating sheet is for forming the electrode holder 29. Specifically, first an insulating sheet (for example, a resin sheet as described above) is prepared. The insulating sheet is then cut to a shape and size that conforms to the outer shape of the electrode assembly 20A, and folded to form a bottomed rectangular tubular sheet molded body 29X (see Figure 10). The sheet molded body 29X here has a roughly rectangular first part, a pair of second parts extending from the long side of the first part and facing each other, and a pair of third parts extending from the short side of the first part and facing each other.

[0067] A bottomed rectangular tubular sheet molded body 29X is placed over the combined object 300 in Figure 9 from above in the vertical direction VD (see also Figure 10). As a result, the upper end surface of the electrode assembly 20A in the vertical direction VD is covered by the first part of the sheet molded body 29X. The first part has through holes at the positions of the positive electrode current collector 50 and the negative electrode current collector 60, and the positive electrode current collector 50 and the negative electrode current collector 60 are exposed from the sheet molded body 29X. In addition, the sides of the electrode assembly 20A are covered by the second and third parts of the sheet molded body. The length of the second and third parts of the sheet molded body 29X in the vertical direction VD is longer than the side of the electrode assembly 20A. Therefore, a part of the sheet molded body 29X (specifically, the part of the second part that protrudes from the side of the electrode assembly 20A) is housed in the recess 290r of the pressing jig 200.

[0068] In this embodiment, a spacer 80 (see Figure 10) is further placed over the combined object 300 shown in Figure 9 from above in the vertical direction VD. As a result, the base portion 80b of the spacer 80 is placed on the upper end surface of the electrode assembly 20A in the vertical direction VD. Through holes are provided in the base portion 80b of the spacer 80 at the positions of the positive electrode current collector 50 and the negative electrode current collector 60, and the positive electrode current collector 50 and the negative electrode current collector 60 are exposed from the spacer 80. Although the spacer 80 is separate from the sheet molded body 29X in this example, the spacer 80 may be pre-integrated with the sheet molded body 29X.

[0069] (Step 2) In the insertion step, the electrode assembly 20A is inserted into the case body 12. Figure 10 is an explanatory diagram of the insertion step. In this embodiment, first the case body 12 is prepared. The case body 12 may be a purchased item supplied by a supplier, etc., or it may be manufactured by the manufacturer. In some embodiments, it is preferable that the case body 12 has terminals (positive electrode terminal 30 and / or negative electrode terminal 40) attached to the bottom wall 12a in advance, as shown in the upper part of Figure 10. It is preferable that the terminals are attached to the bottom wall 12a in an insulated state from the bottom wall 12a via an insulating member (gasket 90 in this case). The method of attaching the terminals is not particularly limited. Here, the terminals are attached to the bottom wall 12a in advance by insert molding (integral molding) together with the gasket 90.

[0070] In other words, the case body 12 is prepared as a single molded product integrated with the gasket 90 and terminals (positive terminal 30 and / or negative terminal 40). However, in other embodiments, the terminals may be attached to the bottom wall 12a by crimping (riveting) or the like. Also, as described in the modified example (2) below, the terminals do not necessarily have to be attached beforehand, and can be attached to the bottom wall 12a in an insertion process or joining process, for example, as described below.

[0071] Next, as shown by the arrows in Figure 10, the electrode assembly 20A (combined product 300) encased in the sheet molded body 29X is inserted into the case body 12. For example, the electrode assembly 20A is inserted through the opening 12h of the case body 12 so that the side with the current collectors (positive electrode current collector 50 and / or negative electrode current collector 60) is facing the bottom wall 12a. Alternatively, the case body 12 may be placed over the electrode assembly 20A from above in the vertical direction VD.

[0072] In this embodiment, the electrode assembly 20A is inserted into the case body 12 with at least a portion of the pressing jig 200 (here, the first protrusion 210 and the second protrusion 220) positioned inside the electrode assembly 20A. This makes it easier to more reliably bring the protrusions 210 and 220 of the pressing jig 200 into contact with the current collectors (positive electrode current collector 50 and / or negative electrode current collector 60). Consequently, in the joining process (step 3) described later, it becomes easier to more stably bring the current collectors into contact with the terminals (positive electrode terminal 30 and / or negative electrode terminal 40).

[0073] Furthermore, in this embodiment, since the pressing jig 200 has a support portion 290, it is possible to prevent the electrode assembly 20A from being housed in the case body 12 in a tilted state, and the electrode assembly 20A can be stably inserted into the case body 12. In addition, since the end face of the electrode body 20 is protected by the support portion 290, damage to the electrode body 20 can be suppressed.

[0074] In this embodiment, as shown in Figure 10, the electrode assembly 20A is in an upright position along the vertical direction VD, and the bottom wall 12a of the case body 12 is in an inverted position facing upwards in the vertical direction VD. However, in other embodiments, the electrode assembly 20A may be inserted into the case body 12 without being in an upright position, with the side walls of the case body 12 (a pair of long side walls 12b or a pair of short side walls 12c) positioned above and below the vertical direction VD, and the short or long side of the bottom wall 12a extending in the vertical direction.

[0075] Figure 11 is a schematic longitudinal cross-sectional view of the positive electrode side of the second combined unit 400. As shown in Figure 11, in this embodiment, when the electrode assembly 20A is inserted into the case body 12, the second connection portion 52 of the positive electrode current collector member 50 is inserted through the through hole 30h of the positive electrode terminal 30. The end face of the second connection portion 52 of the positive electrode current collector member 50 is flush with the periphery of the through hole 30h of the positive electrode terminal 30. Although not shown in the figure, similarly, the second connection portion 62 of the negative electrode current collector member 60 is inserted through the through hole 40h of the negative electrode terminal 40. The end face of the second connection portion 62 of the negative electrode current collector member 60 is substantially flush with the periphery of the through hole 40h of the negative electrode terminal 40.

[0076] Furthermore, in the second combined object 400, the case body 12 is positioned between a pair of ribs 230 of the pressing jig 200. The pair of ribs 230 sandwich a pair of long side walls 12b of the case body 12. Each pair of ribs 230 faces the outer surface of the case body 12 (more specifically, the outer surface of the pair of long side walls 12b). Also, a part of the sheet molded body 29X for forming the electrode body holder 29 (more specifically, the part of the second and third parts that is longer than the side surface of the electrode body assembly 20A) is housed in the recess 290r of the pressing jig 200.

[0077] (Step 3) In the joining process, after the insertion process, the first current collector is pressed against the first electrode terminal by a pressing jig 200 (here, the first protrusion 210 or the second protrusion 220) located inside the electrode assembly 20A, and the first electrode terminal and the first current collector are joined. By joining the first current collector and the first electrode terminal in this manner while they are in precise contact with the pressing jig 200, a highly conductive conductive path can be stably formed. Ultimately, a highly conductive energy storage device 100 can be realized.

[0078] Figure 12 is an explanatory diagram of the joining process. Here, the vicinity of the positive electrode terminal 130 is shown in magnified view. As shown in Figure 12, in this embodiment, with the case body 12 in an inverted position with the bottom wall 12a facing upward in the vertical direction VD, the pressing jig 200 is pressed from the opening 12h side, and the first projection 210 of the pressing jig 200 presses the first connection portion 51 of the positive electrode current collector member 50 against the periphery of the through hole 30h of the positive electrode terminal 30. This maintains the state in which the second connection portion 52 of the positive electrode current collector member 50 is inserted into the through hole 30h of the positive electrode terminal 30. Preferably, the end face of the second connection portion 52 and the periphery of the through hole 30h of the positive electrode terminal 30 are kept substantially flush. Then, with the recess 51r of the positive electrode current collector member 50 pressed against the positive electrode terminal 30, the second connection portion 52 of the positive electrode current collector member 50 and the positive electrode terminal 30 are joined. More specifically, the tip of the second connecting portion 52 of the positive electrode current collector 50 and the outer surface of the positive electrode terminal 30 are joined on the outer side of the case body 12, at the periphery of the through hole 30h of the positive electrode terminal 30. This allows the positive electrode current collector 50 and the positive electrode terminal 30 to be stably joined.

[0079] In this embodiment, as shown in Figure 12, the width W1 of the first projection 210 of the pressing jig 200 and the width W2 of the recess 51r of the positive electrode current collector member 50 are W1 > W2, which suppresses the tilt of the positive electrode current collector member 50 and makes it easier to maintain the positive electrode current collector member 50 horizontally. This suppresses displacement of the positive electrode current collector member 50 and allows the positive electrode current collector member 50 and the pressing jig 200 to come into stable contact. Also in this embodiment, as shown in Figure 11, the projection height T1 of the first projection 210 and the height T2 of the electrode body 20 are T1 > T2, which allows the positive electrode current collector member 50 to come into stable contact with the positive electrode terminal 30.

[0080] Furthermore, in this embodiment, since the pressing jig 200 has a support portion 290, the self-weight of the electrode body 20 can be supported by the support portion 290 even when the case body 12 is in an inverted position. This suppresses damage to the positive electrode tab group 27 and the negative electrode tab group 28.

[0081] In this embodiment, since the pressing jig 200 also has a second projection 220, the second electrode terminal and the second current collector are joined together on the negative electrode side as well, with the second current collector pressed against the second electrode terminal by the pressing jig 200. Specifically, the first connection portion 61 of the negative electrode current collector 60 is pressed against the periphery of the through hole 40h of the negative electrode terminal 40 by the second projection 220 of the pressing jig 200. This maintains the state in which the second connection portion 62 of the negative electrode current collector 60 is inserted into the through hole 40h of the negative electrode terminal 40. Preferably, the end face of the second connection portion 62 and the periphery of the through hole 40h of the negative electrode terminal 40 are kept substantially flush. Then, with the recess 61r of the negative electrode current collector 60 pressed against the negative electrode terminal 40, the second connection portion 62 of the negative electrode current collector 60 and the negative electrode terminal 40 are joined together. More specifically, the tip of the second connection portion 62 of the negative electrode current collector 60 and the outer surface of the negative electrode terminal 40 are joined on the outer side of the case body 12, at the periphery of the through hole 40h of the negative electrode terminal 40.

[0082] The joining method is not particularly limited. In some embodiments, it is preferable to weld the case body 12 by irradiating it with an energy ray such as a laser from the outside (the outer surface side of the bottom wall 12a). By joining from the outside of the case body 12, the joint can be visually inspected, making it easier to join the current collector and the terminal more stably. In this embodiment, an annular (for example, circular) joint J is formed along the through hole 30h.

[0083] (Step 4) In the removal step, after the joining step, the pressing jig 200 is removed from the electrode assembly 20A. In this embodiment, a part of the pressing jig 200 (for example, a pair of ribs 230) is grasped and the pressing jig 200 is removed from the opening 12h of the case body 12. This increases the energy density of the energy storage device 100 by the amount of the pressing jig 200. This step may be performed with the bottom wall 12a of the case body 12 facing upward in the vertical direction VD, or with the side walls of the case body 12 (a pair of long side walls 12b or a pair of short side walls 12c) positioned above and below the vertical direction VD, and with the short or long side of the bottom wall 12a extending vertically.

[0084] In some embodiments, when removing the pressing jig 200, it is preferable to support the end of the electrode body 20 on the opening 12h side with a separate (second) jig. This reduces the load applied to the tab group (positive electrode tab group 27 and / or negative electrode tab group 28) and the joint J when removing the pressing jig 200.

[0085] In this embodiment, the pressing jig 200 is removed after the joining process, but as described in the modified example (3) below, the pressing jig 200 does not need to be removed. In other words, the pressing jig 200 may be held inside the electrode assembly 20A in the state of the energy storage device 100.

[0086] In this embodiment, next, a portion of the sheet molded body 29X that was positioned in the recess 290r of the pressing jig 200 (specifically, the portion of the second and third parts that is longer than the side surface of the electrode assembly 20A) is folded. Preferably, the second and third parts of the sheet molded body 29X are folded into a substantially L-shape so as to cover the end face of the electrode assembly 20A. This forms the electrode holder 29.

[0087] (Step 5) 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 joint 10w and seals the case 10. The joining method may be the same as in the conventional method and is not particularly limited. In some embodiments, it is preferable to weld the fitting portion between the case body 12 and the sealing plate 14 by irradiating it with an energy ray such as a laser along the periphery of the opening 12h. The energy storage device 100 can be manufactured in this manner.

[0088] <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).

[0089] 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.

[0090] (1) Current collector and electrode tab: (1-1) For example, in the embodiment described above, the positive electrode current collector 22c of the positive electrode 22 was a metal foil, specifically an aluminum foil. Also, the negative electrode current collector 24c of the negative electrode 24 was a metal foil, specifically a copper foil. However, it is not limited to this. In a modified example, the current collector (positive electrode current collector 22c and / or negative electrode current collector 24c, preferably both) is preferably configured to include an insulating core (e.g., a resin layer) and a pair of metal layers formed on a pair of surfaces (both sides) of the core. Although not particularly limited, the total thickness of the current collector is preferably 20 μm or less, and more preferably 10 μm or less.

[0091] The core is preferably made of a resin such as polyethylene terephthalate (PET), nylon, polypropylene (PP), or polyethylene (PE). The thickness of the core is preferably 50% or more of the total thickness of the current collector, which is 100%. This reduces the weight of the electrode body 20, and effectively suppresses damage to the electrode tabs and electrode body 20 when the electrode tabs (positive electrode tab 22t and / or negative electrode tab 24t) are positioned vertically downwards when the energy storage device 100 is in use. Furthermore, the metal layer is preferably made of materials such as aluminum, aluminum alloy, copper, copper alloy, nickel, nickel alloy, iron, or iron alloy.

[0092] (1-2) In addition, for example, in the embodiment described above, the electrode tabs (positive electrode tab 22t and / or negative electrode tab 24t) were regions in which the active material layer (positive electrode active material layer 22a and / or negative electrode active material layer 24a) of the current collector (positive electrode current collector 22c and / or negative electrode current collector 24c) was not formed. However, it is not limited to this. The electrode tabs may be separate components from the current collector. For example, if the current collector has a configuration including a core and a pair of metal layers as described above, a conductive member made of a metal foil or metal plate thicker than the metal layers may be attached to the metal layer portion, and the conductive member may be connected to the current collector (positive electrode current collector 50 and / or negative electrode current collector 60) as an electrode tab.

[0093] (2) Terminal installation: For example, in the embodiment described above, as shown in Figure 10, the terminals (positive terminal 30 and / or negative terminal 40) were pre-attached to the bottom wall 12a of the case body 12 in the (step 2) insertion step. That is, the case body 12 was prepared as a single molded product integrated with the gasket 90 and the terminals (positive terminal 30 and / or negative terminal 40). However, it is not limited to this. The terminals can also be attached to the bottom wall 12a in the (step 3) joining step, for example. In one example, first, in the (step 2) insertion step, the terminal exit holes 18, 19 of the bottom wall 12a are sandwiched between the terminals (positive terminal 30 and / or negative terminal 40) and the conductive members (positive current collector 50 and / or negative current collector 60) from the inside and outside of the case body 12, and at least a part of the conductive members is inserted into the terminal through holes 30h, 40h. Then, in the (step 3) joining step, the terminals and the conductive members are joined (for example, by welding). This allows the terminals to be attached to the bottom wall 12a (via insulating material, if necessary) almost simultaneously with the formation of the joint J.

[0094] (3) Arrangement of the pressing fixture: For example, in the embodiment described above, as shown in Figures 8 and 9, the first protrusion 210 and the second protrusion 220 of the pressing jig 200 were positioned between the first electrode body 20 and the second electrode body 20 during the lamination process (step 1C). However, the embodiment is not limited to this. The first protrusion 210 and the second protrusion 220 of the pressing jig 200 may be positioned, for example, inside one electrode body 20. In one example, if the electrode body 20 is a laminated electrode body, the first electrode body 20 and the second electrode body 20 may be sandwiched between a pair of separators 26 from the lamination direction and positioned inside one electrode body 20. Alternatively, if the electrode body assembly 20A is a single wound electrode body 20, a cylindrical body may be formed in the preparation process (step 1A) using a shaft that also functions as the pressing jig 200 (having the function of the pressing jig 200). In this case, in the state of the energy storage device 100, the pressing jig 200 is typically held inside the electrode assembly 20A. Alternatively, the pressing jig 200 may be inserted into the wound electrode after the wound electrode has been fabricated.

[0095] Furthermore, in this embodiment, as can be seen from Figure 11, a terminal (positive electrode terminal 30 and / or negative electrode terminal 40) is provided in the center of the bottom wall 12a in the short-side direction X, and the first protrusion 210 and the second protrusion 220 are arranged in the center of the electrode assembly 20A (between the first electrode body 20 and the second electrode body 20) in the short-side direction X. However, this is not limited to this. For example, if the number of electrode bodies 20 included in the electrode assembly 20A is odd (for example, three), the position of the terminal in the short-side direction X may be offset from the center, and the positions of the first protrusion 210 and the second protrusion 220 may be offset from the center of the electrode assembly 20A.

[0096] (4) Conductive path between terminal and current collector: In the modified example, unlike the embodiment described above, the joint J may be formed inside the case body 12. By providing the joint J inside the case body 12 (for example, inside the through hole 30h), it is possible to prevent the joint J from interfering with other members and becoming damaged or broken.

[0097] Furthermore, in this modified example, the positive electrode terminal 30 does not need to have a through hole 30h. Figure 13 is a partially enlarged view of the vicinity of the positive electrode terminal 130 in this modified example. As shown in Figure 13, the positive electrode terminal 130 has a cylindrical portion 131 located in the terminal lead-out hole 18 of the bottom wall 12a of the case body. The cylindrical portion 131 has a thin-walled portion 131t instead of the through hole described above. The thin-walled portion 131t is located opposite the positive electrode current collector 150. In this example, the thin-walled portion 131t is located inside the case body 12. Also, the positive electrode current collector 150 is flat and, unlike the embodiment described above, does not have a columnar second connecting portion. In this modified example, the positive electrode terminal 130 and the positive electrode current collector 150 are joined (for example, by welding) so as to penetrate the thin-walled portion 131t of the positive electrode terminal 130, and a joint portion Jt is formed inside the case body 12. By providing the joint Jt inside the case body 12, it is possible to prevent the joint Jt from interfering with other components and becoming damaged or broken.

[0098] (5) Sequence of processes: For example, in the embodiment described above, after the placement step (step 1) in which the pressing jig 200 is placed inside the electrode assembly 20A, an insertion step (step 2) is performed in which the electrode assembly 20A is inserted inside the case body 12. However, it is not limited to this. In a modified example, the placement step may be performed after the insertion step. In this case, for example, first in the insertion step, the case body 12 (preferably an integrally molded product integrated with terminals) is prepared, and the electrode assembly 20A is first inserted into the case body 12. Next, in the placement step, the pressing jig 200 may be inserted into the inside of the electrode assembly 20A (for example, between multiple electrode bodies 20) from the opening 12h side of the case body 12.

[0099] As described above, specific embodiments of the technology disclosed herein include those described in the following sections. Item 1: An electrode assembly comprising one or more electrode bodies including a first electrode and a second electrode; a case for housing the electrode assembly; a first current collector member electrically connected to the first electrode within the case; and a first electrode terminal electrically connected to the first current collector member, wherein the case comprises a bottomed cylindrical case body having a bottom wall, side walls provided on the outer periphery of the bottom wall, and an opening facing the bottom wall; and a sealing plate for sealing the opening of the case body, and the first electrode terminal A method for manufacturing an energy storage device, wherein a pressing jig is provided on the bottom wall of the case body, the method comprising: an arrangement step of arranging at least a part of the pressing jig inside the electrode body assembly; an insertion step of inserting the electrode body assembly inside the case body; and a joining step of joining the first electrode terminal and the first current collector member after the insertion step, with the pressing jig positioned inside the electrode body assembly pressing the first current collector member against the first electrode terminal. Item 2: The method for manufacturing an energy storage device according to Item 1, further comprising a removal step of removing the pressing jig from the electrode assembly after the joining step. Item 3: A method for manufacturing an energy storage device according to item 1 or 2, wherein the insertion step is performed after the arrangement step, and in the insertion step, the electrode assembly is inserted into the case body with at least a portion of the pressing jig positioned inside the electrode assembly. Item 4: The method for manufacturing an energy storage device according to any one of items 1 to 3, wherein the pressing jig has a support portion that supports the end face of the electrode assembly. Item 5: The method for manufacturing an energy storage device according to any one of items 1 to 4, wherein the pressing jig has ribs facing the outer surface of the side wall of the case body when inserting the electrode body assembly into the case body. Item 6: The method for manufacturing an energy storage device according to Item 4, wherein the support portion of the pressing jig has a recess on the surface facing the electrode assembly, and in the arrangement step, an insulating sheet is placed around the electrode assembly, and a portion of the insulating sheet is housed in the recess. Item 7: A method for manufacturing an energy storage device according to any one of items 1 to 6, further comprising: a second current collector member electrically connected to the second electrode within the case; and a second electrode terminal electrically connected to the second current collector member within the case and provided on the bottom wall of the case body, wherein in the joining step, the second electrode terminal and the second current collector member are joined while the second current collector member is pressed against the second electrode terminal by the pressing jig. Item 8: A method for manufacturing an energy storage device according to any one of items 1 to 7, wherein the electrode assembly comprises a first electrode and a second electrode, each further comprising a separator, and in the arrangement step, at least a portion of the pressing jig is positioned between the first electrode and the second electrode, the portion of the first electrode that the pressing jig contacts is the separator, and the portion of the second electrode that the pressing jig contacts is the separator. Item 9: A method for manufacturing an energy storage device according to any one of items 1 to 7, wherein the electrode assembly comprises a first electrode body and a second electrode body, the first electrode body having a group of first electrode tabs comprising a plurality of first electrode tabs, the second electrode body having a group of second electrode tabs comprising a plurality of second electrode tabs, the arrangement step comprising a joining step of joining the group of first electrode tabs of the first electrode body and the group of second electrode tabs of the second electrode body to a single first current collector to produce a combined product, and a stacking step of stacking the first electrode body and the second electrode body after the joining step such that the pressing jig is positioned between the first electrode body and the second electrode body, and the insertion step is performed after the arrangement step. [Explanation of symbols]

[0100] 10 cases 12 Case body 14 Sealing plate 20 Electrode body 20A Electrode Assembly 22 Positive electrode (1st electrode / 2nd electrode) 24 Negative electrode (1st electrode / 2nd electrode) 100 Energy storage devices 200 Pressing jigs 210 1st protrusion 220 Second protrusion 230 Ribs 290 Support part

Claims

1. An electrode assembly comprising one or more electrode bodies including a first electrode and a second electrode, A case for housing the electrode assembly, A first current collector member electrically connected to the first electrode within the case, A first electrode terminal electrically connected to the first current collector, Equipped with, The aforementioned case is, A bottomed cylindrical case body having a bottom wall, a side wall provided on the outer edge of the bottom wall, and an opening facing the bottom wall, A sealing plate that seals the opening of the case body, Equipped with, A method for manufacturing an energy storage device, wherein the first electrode terminal is provided on the bottom wall of the case body, The arrangement step involves placing at least a portion of the pressing jig inside the electrode assembly, An insertion step of inserting the electrode assembly into the inside of the case body, After the insertion step, the first current collector is pressed against the first electrode terminal by the pressing jig positioned inside the electrode assembly, and the first electrode terminal and the first current collector are joined together in this joining step. A method for manufacturing an energy storage device, including the method described above.

2. The process further includes a removal step of removing the pressing jig from the electrode assembly after the bonding step, A method for manufacturing an energy storage device according to claim 1.

3. After the arrangement step, the insertion step is performed. In the insertion step, with at least a portion of the pressing jig positioned inside the electrode assembly, the electrode assembly is inserted into the case body. A method for manufacturing an energy storage device according to claim 1 or 2.

4. The pressing jig has a support portion that supports the end face of the electrode assembly. A method for manufacturing an energy storage device according to claim 3.

5. The pressing jig has ribs facing the outer surface of the side wall of the case body when inserting the electrode assembly into the case body. A method for manufacturing an energy storage device according to claim 3.

6. The support portion of the pressing jig has a recess on the surface facing the electrode assembly, In the arrangement step, an insulating sheet is placed around the electrode assembly, and a portion of the insulating sheet is housed in the recess. A method for manufacturing an energy storage device according to claim 4.

7. The aforementioned energy storage device is A second current collector member electrically connected to the second electrode within the case, The second electrode terminal is electrically connected to the second current collector within the case and is provided on the bottom wall of the case body, Furthermore, In the joining process, the second current collector is pressed against the second electrode terminal by the pressing jig, and the second electrode terminal and the second current collector are joined together. A method for manufacturing an energy storage device according to claim 1 or 2.

8. The electrode assembly includes a first electrode and a second electrode. The first electrode body and the second electrode body each further include a separator, In the arrangement step, at least a portion of the pressing jig is positioned between the first electrode body and the second electrode body. In the first electrode body, the portion that the pressing jig contacts is the separator. In the second electrode body, the portion that the pressing jig contacts is the separator. A method for manufacturing an energy storage device according to claim 1 or 2.

9. The electrode assembly includes a first electrode and a second electrode. The first electrode body has a group of first electrode tabs, which includes a plurality of first electrode tabs. The second electrode body has a group of second electrode tabs, which includes a plurality of second electrode tabs. The aforementioned arrangement step is, A joining step of joining the first electrode tab group of the first electrode body and the second electrode tab group of the second electrode body to a single first current collector member to produce a combined object, After the combining step, a lamination step is performed in which the first electrode body and the second electrode body are stacked on top of each other so that the pressing jig is positioned between the first electrode body and the second electrode body. Includes, The insertion step is performed after the arrangement step. A method for manufacturing an energy storage device according to claim 1 or 2.

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