Energy storage device and method for manufacturing the same

Abstract

To provide an energy storage device with high conductivity. [Solution] The present invention provides a method for manufacturing an energy storage device comprising an electrode body 20, a case, and a first electrode terminal 30 attached to the bottom wall 12a of the case. This manufacturing method includes a connection step of electrically connecting a first current collector 50 to the first electrode of the electrode body 20, an insertion step of inserting the electrode body 20 into the case body and arranging at least a part 52 of the first current collector 50 in the first recess 30r of the first electrode terminal 30, and a welding step of irradiating an energy ray LB from the first electrode terminal 30 side and welding the portion of the first current collector 50 arranged in the first recess 30r to the first electrode terminal 30.

Description

Technical Field

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

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 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 (first current collecting member) 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 first current collecting member and the first electrode terminal, and the difficulty of joining increases. Therefore, there is a need to stably join the first current collecting member and the first electrode terminal to provide a power storage device with high conduction reliability.

[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 relates to 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 via a first current collector, 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 that seals the opening of the case body, wherein the first electrode terminal is attached to the bottom wall of the case body and has a first recess on the inside of the case body, and the first current collector is at least partially above A manufacturing method is provided, comprising: a connection step of electrically connecting the first current collector member to the first electrode, wherein the first current collector member is placed in a first recess, and the portion of the electrode body placed in the first recess is welded to the first electrode terminal; an insertion step of inserting the electrode body into the case body after the connection step and placing at least a portion of the first current collector member in the first recess of the first electrode terminal; and a welding step of irradiating the portion of the first current collector member placed in the first recess with the first electrode terminal after the insertion step by irradiating it with an energy ray from the first electrode terminal side.

[0007] According to the method described above, the first current collector and the first electrode terminal can be stably welded together, improving the conductivity reliability of the joint. Consequently, a highly reliable 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 diagram showing the configuration of the electrode body. [Figure 4] Figure 4 is a magnified view of the area near the positive terminal in Figure 2. [Figure 5] Figure 5(A) is a schematic plan view of the spacer, and Figure 5(B) is a schematic cross-sectional view of the spacer. [Figure 6]Figure 6 is a schematic longitudinal cross-sectional view of a one-piece molded product including the case body. [Figure 7] Figure 7 is a longitudinal cross-sectional view of the combined object. [Figure 8] Figure 8 is an explanatory diagram of the welding process. [Figure 9] Figure 9 is a schematic longitudinal cross-sectional view showing an electrode body according to a modified example. [Figure 10] Figure 10 is a modified version of Figure 2. [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 the line II-II 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.

[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, 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 housing the electrode body 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 body 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 on the outer peripheral edge of the bottom wall, and an opening facing the bottom wall. Here, the case body 12 is a bottomed and angular container having an opening 12h on the upper surface. Specifically, as shown in FIG. 1, the case body 12 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, and is a bottomed angular cylindrical shape. The case body 12 is preferably a bottomed angular cylindrical 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-like member. The sealing plate 14 faces the bottom wall 12a of the case body 12. Here, the sealing plate 14 is substantially rectangular. The sealing plate 14 constitutes the upper 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 FIG. 2, a joint portion (e.g., a welding joint portion) 10w is formed at the fitting portion between the case body 12 and the sealing plate 14. Thereby, the case 10 is hermetically sealed.

[0018] As shown in FIGS. 1 and 2, an electrolytic solution injection hole 15, a gas discharge valve 17, and terminal lead-out holes 18 and 19 are provided in the bottom wall 12a of the case body 12. The electrolytic solution injection hole 15 is a through hole for injecting the electrolytic solution into the case 10 after assembling the sealing plate 14 to the case body 12. The electrolytic solution injection hole 15 is sealed by a sealing member 16 after injecting the electrolytic solution. Incidentally, the electrolytic solution injection hole 15 may be provided in the sealing plate 14. The gas discharge valve 17 is a thin-walled portion configured to break when the pressure in the case 10 becomes a predetermined value or more and discharge the gas in the case 10 to the outside. Incidentally, the gas discharge valve 17 may be provided in the sealing plate 14. The terminal lead-out holes 18 and 19 are respectively formed at both ends in the long side direction Y of the bottom wall 12a. The terminal lead-out holes 18 and 19 penetrate the bottom wall 12a. As will be described in detail later, a positive electrode terminal 30 and a negative electrode terminal 40 are respectively inserted into the terminal lead-out holes 18 and 19 of the bottom wall 12a.

[0019] The electrode body 20 is housed inside the case 10. The number of electrode bodies 20 housed in one case 10 is not particularly limited; there may be one or multiple (for example, two or more, three or more). As shown in Figure 2, the electrode body 20 is placed inside the case 10 covered by an electrode body holder 29 made of a resin sheet. This prevents the electrode body 20 from coming into direct contact with the case body 12. The material of the electrode body holder 29 may 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).

[0020] Figure 3 is a schematic diagram showing the configuration of the electrode body 20. In Figure 3, 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.

[0021] As shown in Figure 3, 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, as described in the modified example (2) below, the electrode body 20 may be a stacked electrode body. In this embodiment, the electrode body 20 has a flattened external shape. In this embodiment, the electrode body 20 is housed inside the case 10 such that the winding axis WL substantially coincides with the vertical direction Z. 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."

[0022] As shown in Figure 3, 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).

[0023] As shown in Figure 3, 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. The number of positive electrode tabs 22t attached to one electrode body 20 can be several tens or more, for example, about 40 to 60. Each of the plurality of positive electrode tabs 22t is convex and protrudes outward (to the left side in Figure 3). The plurality of positive electrode tabs 22t are identical in shape and are each approximately rectangular. 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 part 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.

[0024] Multiple positive electrode tabs 22t are stacked at one end of the electrode body 20 in the winding axis direction WD, forming a positive electrode tab group 27 (see Figure 2). As shown in Figure 2, the tip of the positive electrode tab group 27 (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 positive electrode tab group 27 (multiple positive electrode tabs 22t) and the positive electrode current collector 50. Preferably, the positive electrode 22 is electrically connected to the positive electrode current collector 50 via the positive electrode tab group 27.

[0025] As shown in Figure 3, 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.

[0026] As shown in Figure 3, 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.

[0027] As shown in Figure 3, 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).

[0028] As shown in Figure 3, 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 3) as the positive electrode tabs 22t. The multiple negative electrode tabs 24t are provided at predetermined intervals (intermittently) along the longitudinal direction LD. The number of negative electrode tabs 24t attached to one electrode body 20 is approximately the same as the number of positive electrode tabs 22t, and can be several tens or more. Each of the multiple negative electrode tabs 24t is convex and protrudes outward (left side in Figure 3). The multiple negative electrode tabs 24t are identical in shape and are approximately rectangular. 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. 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.

[0029] 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. Preferably, the negative electrode 24 is electrically connected to the negative electrode current collector 60 via the negative electrode tab group 28. Preferably, the electrode body 20 has a positive electrode tab group 27 and a negative electrode tab group 28 at one end.

[0030] As shown in Figure 3, 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, various additives, etc.

[0031] As shown in Figure 3, 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 (e.g., a heat resistance layer (HRL) or adhesive layer) formed on at least one surface of the base material. The heat resistance 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.

[0032] 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.

[0033] As shown in Figures 1 and 2, the positive terminal 30 and the negative terminal 40 are attached to the bottom wall 12a of the bottomed cylindrical 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). The positive terminal 30 is inserted through the terminal lead-out hole 18 of the bottom wall 12a, with a portion exposed to the outside of the case 10. The negative terminal 40 is inserted through the terminal lead-out hole 19 of the bottom wall 12a, with a portion exposed to the outside of the case 10. When the positive electrode 22 is the "first electrode", the positive terminal 30 is an example of the "first electrode terminal". When the negative electrode 24 is the "first electrode", the negative terminal 40 is an example of the "first electrode terminal".

[0034] 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.

[0035] 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. For example, the terminals can be fixed to the case body 12 by connecting them to an external conductive member located on the outside of the case body 12 by crimping and / or welding. Alternatively, the terminals can be fixed to the case body 12 by crimping and / or welding to an internal conductive member located on the inside of the case body 12. Alternatively, they may be fixed to the bottom wall 12a via an adhesive layer (such as an adhesive).

[0036] In the following explanation, the case where the positive electrode 22 is the "first electrode" will be used as an example, but the negative electrode 24 can also be configured similarly. In that case, the term "positive electrode" below can be appropriately replaced with "negative electrode". The technology disclosed herein is more preferably applied to both the positive electrode 22 side and the negative electrode 24 side.

[0037] Figure 4 is a magnified view of the vicinity of the positive electrode terminal 30. The positive electrode terminal 30 is inserted through a terminal lead-out hole 18 in the bottom wall 12a and extends from the inside (upper side of Figure 4) to the outside (lower side of Figure 4) 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. 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. As shown in Figure 4, the positive electrode terminal 30 is electrically connected here to the positive electrode tab group 27 of the positive electrode 22. The positive electrode terminal 30 is preferably made of metal, and more preferably of aluminum or an aluminum alloy, for example. The positive electrode terminal 30 has a first recess 30r. The positive terminal 30 further includes a cylindrical portion 31, an outer flange portion 32, an inner flange portion 33, a second recess 32r, and a partition wall 30s.

[0038] The cylindrical portion 31 is the part located inside the terminal exit hole 18. The cylindrical portion 31 extends in the vertical direction Z. Although not shown in the figure, the cylindrical portion 31 is annular in XY plan view. That is, the outer shape of the cylindrical portion 31 is cylindrical. The outer flange portion 32 is connected to the lower end of the cylindrical portion 31 (the end on the outer surface side of the bottom wall 12a) and is a part with a larger outer shape than the cylindrical portion 31. The outer flange portion 32 is located outside the case body 12 (on the outer surface side of the bottom wall 12a) of the terminal exit hole 18. As shown in Figure 1, the outer flange portion 32 is approximately rectangular in XY plan view. The inner flange portion 33 is connected to the upper end of the cylindrical portion 31 (the end on the electrode body 20 side) and is a part with a larger outer shape than the cylindrical portion 31. The inner flange portion 33 is positioned on the inside side (electrode body 20 side) of the case body 12 relative to the terminal lead-out hole 18. The outer shape of the outer flange portion 32 or the inner flange portion 33 can be larger than the inner diameter of the terminal lead-out hole 18. In addition, the plan view shape of the outer flange portion 32 and the inner flange portion 33 may be circular.

[0039] The first recess 30r is provided on the inside of the case body 12, as shown in Figure 4. The first recess 30r is provided along the terminal lead hole 18. The first recess 30r is provided within the terminal lead hole 18. The first recess 30r is provided on the inner circumference of the cylindrical portion 31. The first recess 30r extends from the cylindrical portion 31 to the outer flange portion 32. The first recess 30r is formed in a cylindrical shape here. The first recess 30r is an unpenetrating hole and has a bottom surface 30b. The bottom surface 30b is preferably circular in shape in an XY plan view. In an XY plan view, the center of the bottom surface 30b coincides with the center of the terminal lead hole 18 here. A part of the positive electrode current collector member 50 (specifically the second connection portion 52), which will be described later, is placed in the first recess 30r.

[0040] In this embodiment, the inner flange portion 33 has a chamfered portion 33c at the corner on the first recess 30r side (the portion that can first come into contact with the positive electrode current collector 50). The chamfered portion 33c is formed continuously along the outer edge of the first recess 30r. The shape of the chamfered portion 33c is not particularly limited, but for example, it can be a C-shaped chamfered surface with the corner cut off at a predetermined angle (e.g., 45 degrees), or an R-shaped chamfered surface with the corner rounded. By providing a chamfered portion 33c on the inner flange portion 33, it becomes easier to insert the positive electrode current collector 50 into the first recess 30r of the positive electrode terminal 30 in the insertion step (step 4) of the manufacturing method described later, thereby improving insertability.

[0041] The second recess 32r is provided on the outer surface of the positive terminal 30, as shown in Figure 4. The second recess 32r is provided on the outer flange portion 32. The second recess 32r is provided on the outside of the case body 12. The second recess 32r is formed in a cylindrical shape here. Although not particularly limited, it is preferable that the length of the long side Y of the second recess 32r (here, the diameter) Φ2 is the same as or smaller than the length of the long side Y of the first recess 30r (here, the diameter) Φ1 (Φ2 ≤ Φ1).

[0042] The second recess 32r is located opposite the first recess 30r. In an XY plan view, the second recess 32r is located in a position that overlaps with the first recess 30r. The second recess 32r has a bottom surface 32b. The bottom surface 32b is preferably circular in shape in an XY plan view. In an XY plan view, the center of the bottom surface 32b coincides with the center of the terminal lead-out hole 18. The center of the bottom surface 32b coincides with the center of the bottom surface 30b of the first recess 30r. A welded joint J with the positive electrode current collector member 50 is formed on the bottom surface 32b.

[0043] As shown in Figure 4, the partition wall 30s separates the first recess 30r and the second recess 32r in the vertical direction Z. The partition wall 30s is located on the outer flange portion 32 (outside the case body 12 from the terminal lead-out hole 18). The partition wall 30s extends along the inner surface of the bottom wall 12a. A welded joint J between the partition wall 30s and the positive electrode current collector member 50 is formed continuously from the bottom surface 32b.

[0044] The positive electrode current collector 50 is a conductive member and constitutes a conductive path between the positive electrode 22 (specifically the positive electrode tab group 27) and the positive electrode terminal 30. By interposing the positive electrode current collector 50 between the positive electrode tab group 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 tab 22t and / or the positive electrode terminal 30. As shown in Figure 4, the positive electrode current collector 50 has an asymmetrical shape in the long side direction Y. 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".

[0045] The first connection portion 51 is provided at the upper end (the end on the electrode body 20 side) of the positive electrode current collector member 50. The first connection portion 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 connection portion 51 is joined (for example, by welding such as ultrasonic welding) to the positive electrode tab group 27 (multiple positive electrode tabs 22t). The first connection portion 51 is flat in this case and extends along the inner surface of the bottom wall 12a. As shown in Figure 4, in the long side direction Y, the width of the first connection portion 51 is wider than the width of the positive electrode tab group 27.

[0046] The second connection portion 52 is provided at the lower end (the end on the bottom wall 12a side) of the positive electrode current collector member 50. The second connection portion 52 is a protruding portion (convex portion) that extends from the first connection portion 51. The second connection portion 52 is located on the opposite side of the positive electrode tab group 27, with the first connection portion 51 in between. The second connection portion 52 is located in a position that does not overlap with the positive electrode tab group 27 in an XY plan view. The second connection portion 52 is located within the first recess 30r of the positive electrode terminal 30. The second connection portion 52 is inserted into the first recess 30r of the positive electrode terminal 30. This makes it easier to maintain a more stable electrical connection between the positive electrode terminal 30 and the positive electrode current collector member 50. Therefore, conductivity reliability can be improved.

[0047] The second connecting portion 52 is columnar, specifically cylindrical in shape. Preferably, the second connecting portion 52 is circular in shape when viewed in the XY plane. If both the second connecting portion 52 of the positive electrode current collector 50 and the first recess 30r of the positive electrode terminal 30 are circular in shape when viewed in the XY plane, it becomes easier to insert the second connecting portion 52 into the first recess 30r in the insertion step (step 4) of the manufacturing method described later, thereby improving insertability.

[0048] The second connecting portion 52 has a chamfered portion 52c at the corner of its tip (lower end in Figure 4). The chamfered portion 52c is formed continuously in the circumferential direction. The shape of the chamfered portion 52c is not particularly limited, but for example, it can be a C-shaped chamfer where the corner is cut off at a predetermined angle (e.g., 45 degrees), or an R-shaped chamfer where the corner is rounded. The tip of the second connecting portion 52 is the part that first contacts the first recess 30r of the positive electrode terminal 30 in the insertion step (step 4) of the manufacturing method described later. Having a chamfered portion 52c at the tip of the second connecting portion 52 makes it easier to insert the second connecting portion 52 into the first recess 30r, thereby improving insertability. The tip of the second connecting portion 52 abuts against the bottom surface 30b of the first recess 30r. A welded joint portion J with the positive electrode terminal 30 is formed at the tip of the second connecting portion 52, continuously from the partition wall 30s.

[0049] In the cross-sectional view of Figure 4, the length (here, diameter) Φ3 of the long side Y of the second connection portion 52 is preferably smaller than the diameter Φ1 of the first recess 30r of the positive terminal 30 (Φ3 < Φ1). The ratio of the diameter Φ1 of the first recess 30r to the diameter Φ3 of the second connection portion 52 (Φ1 / Φ3) is preferably slightly greater than 1. The difference (Φ1 - Φ3) between the diameter Φ3 of the second connection portion 52 and the diameter Φ1 of the first recess 30r is preferably 0.5 mm or more, more preferably 0.8 mm or more, and even more preferably 1 mm or more. By ensuring play within the first recess 30r, it becomes easier to insert the second connection portion 52 into the first recess 30r in the insertion step (step 4) of the manufacturing method described later, thereby improving insertability.

[0050] Furthermore, it is preferable that the diameter Φ3 of the second connection portion 52 is larger than the diameter Φ2 of the second recess 32r of the positive electrode terminal 30 (Φ2 < Φ3). This makes it easier to stably weld the positive electrode terminal 30 and the positive electrode current collector member 50 together when energy rays are irradiated into the second recess 32r during the welding process (step 5) of the manufacturing method described later.

[0051] The positive electrode current collector 50 is welded to the positive electrode terminal 30 at the portion located within the first recess 30r of the positive electrode terminal 30. In this embodiment, as shown in Figure 4, the partition wall 30s of the positive electrode terminal 30 (from the bottom surface 32b of the second recess 32r to the bottom surface 30b of the first recess 30r) and the second connecting portion 52 of the positive electrode current collector 50 (the portion located within the first recess 30r, particularly the tip) are welded together. A welded joint J is formed at the boundary between the positive electrode current collector 50 and the positive electrode terminal 30. The welded joint J is a portion that has been melted by irradiation with an energy ray such as laser welding and then solidified.

[0052] In this embodiment, the welded joint J between the positive electrode current collector 50 (first current collector) and the positive electrode terminal 30 (first electrode terminal) extends from the bottom surface 32b of the second recess 32r of the positive electrode terminal 30 to the bottom surface 30b of the first recess 30r, and further extends into the interior of the positive electrode current collector 50. This allows for a stronger bond between the positive electrode terminal 30 and the positive electrode current collector 50, improving the conductivity reliability of the welded joint J.

[0053] As shown in Figures 1 and 2, the welded joint J is located within the second recess 32r. By positioning the welded joint J within the second recess 32r, it becomes difficult for the welded joint J to protrude outward from the outer surface of the bottom wall 12a. The welded joint J is contained within the second recess 32r. This prevents the welded joint J from being damaged or broken by interference with other components or jigs. Furthermore, it allows external connecting members such as busbars to be brought into suitable contact with the outer surface of the positive electrode terminal 30.

[0054] The negative electrode terminal 40 is electrically connected to the negative electrode 24 of the electrode body 20 via the negative electrode current collector 60. The negative electrode terminal 40 has the same configuration as the positive electrode terminal 30. As shown in Figure 2, the negative electrode terminal 40 is electrically connected to the negative electrode tab group 28 of the negative electrode 24. 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 first recess 40r and a second recess 42r.

[0055] The negative electrode current collector 60 is a conductive member and constitutes a conductive path between the negative electrode 24 (specifically the negative electrode tab group 28) and the negative electrode terminal 40. 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. Here, the negative electrode current collector 60 has the same configuration as the positive electrode current collector 50. As shown in Figure 2, 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".

[0056] As shown in Figure 2, the spacer 80 is positioned inside the case 10 between the bottom wall 12a (specifically the inner surface, the upper surface in Figure 2) and the electrode body 20 (specifically the lower surface in Figure 2). The spacer 80 has a portion that is positioned between the positive electrode current collector 50 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 as the material of the electrode body holder 29.

[0057] Figure 5(A) is a schematic plan view of the spacer 80, and Figure 5(B) is a schematic cross-sectional view of the spacer 80. In addition, the side walls of the case body 12 (a pair of long side walls 12b and a pair of short side walls 12c) are shown together with dashed lines in Figure 5(A) and (B). As shown in Figures 5(A) and (B), the spacer 80 has a flat base portion 89 and a pair of support portions 85 and 86. The spacer 80 also has a central through hole 81.

[0058] As shown in Figure 2, the central through-hole 81 is located in the portion opposite to the electrolyte injection hole 15 and the gas discharge valve 17 (the portion that overlaps in the XY plane view). As a result, 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.

[0059] The support portion 85 is the part that supports the conductive path on the positive electrode 22 side during the (step 4) insertion process and (step 5) welding process of the manufacturing method described later. As shown in Figures 5(A) and (B), the support portion 85 is provided with a stepped portion 85s and a through hole 85h. As can be seen from Figure 2, the positive electrode current collector member 50 is positioned in the stepped portion 85s. Here, the first connecting portion 51 is fitted into the stepped portion 85s. The stepped portion 85s is in contact with the electrode body 20 side surface of the positive electrode current collector member 50. The through hole 85h is provided inside the stepped portion 85s. As can be seen from Figure 2, the positive electrode tab group 27 is inserted through the through hole 85h. A notch 85n is provided on one side of the through hole 85h in the short side direction X. In the assembly process described later (Step 3), the conductive path on the positive electrode 22 side is inserted into the support portion 85 via the notch 85n.

[0060] The support portion 86 is the part that supports the conductive path on the negative electrode 24 side during the (step 4) insertion process and (step 5) welding process of the manufacturing method described later. As shown in Figures 5(A) and (B), the support portion 86 is provided with a stepped portion 86s and a through hole 86h. The support portion 86 is provided symmetrically with respect to the support portion 85. As can be seen from Figure 2, the negative electrode current collector 60 is positioned in the stepped portion 86s. Here, the first connecting portion 61 is fitted into the stepped portion 86s. The stepped portion 86s is in contact with the electrode body 20 side surface of the negative electrode current collector 60. The through hole 86h is provided inside the stepped portion 86s. As can be seen from Figure 2, the negative electrode tab group 28 is inserted through the through hole 86h. A notch 86n is provided on one side of the through hole 86h in the short-side direction X (the front side in Figure 5(A), the same side as the notch 85n). In the assembly process (step 3) described later, the conductive path on the negative electrode 24 side is inserted into the support portion 86 through the notch 86n.

[0061] In this case, the spacer 80 is integrated (more specifically, mechanically connected) with the current collector (positive electrode current collector 50 and / or negative electrode current collector 60) by having the conductive path for the positive electrode 22 side located in the support portion 85 and the conductive path for the negative electrode 24 side located in the support portion 86. The spacer 80 is assembled to the current collector. The spacer 80 is attached to the current collector. In this case, the spacer 80 is also integrated (connected) with the electrode body 20 via the current collector.

[0062] As shown in Figure 2, the base portion 89 extends along the bottom wall 12a of the case body 12. As shown in Figure 5(A), in an XY plan view, it is preferable that the outer edge of the spacer 80 (more specifically the base portion 89) abuts against or is close to the inner surface of the side wall of the case body 12. The gap between the spacer 80 and the side wall of the case body 12 (the difference between the inner dimensions of the case body 12 and the outer dimensions of the spacer 80) is preferably 1 mm or less, more preferably 0.8 mm or less, and even more preferably 0.5 mm or less.

[0063] As shown in Figure 5(B), the base portion 89 has a first surface 89a facing the bottom wall 12a and a second surface 89b facing the electrode body 20. The first surface 89a is preferably in contact with or close to the bottom wall 12a. This makes it difficult for the spacer 80 to move in the vertical direction Z (especially towards the bottom wall 12a) even when the energy storage device 100 is positioned such that the bottom wall 12a side is positioned vertically downward. Consequently, damage to the electrode tab group (positive electrode tab group 27 and / or negative electrode tab group 28) and the conduction path can be effectively suppressed, and the conductivity reliability can be improved. The second surface 89b here faces the electrode body 20 via the electrode body holder 29. In this case, it is preferable that the electrode body holder 29 has through holes or notches through which the electrode tab group passes in the portion facing the support portions 85 and 86. As shown in Figure 2, it is preferable that the second surface 89b is in contact with the electrode body 20 (or electrode body holder 29).

[0064] The spacer 80 has a base portion 89 that abuts against or is close to the inner surface of the side wall of the case body 12, and also has support portions 85 and 86, which makes it easier to guide the electrode body 20 and the current collector members (positive electrode current collector member 50 and / or negative electrode current collector member 60) to the desired position in the insertion step (step 4) of the manufacturing method described later. In other words, the spacer 80 can also function as a guide member for the electrode body 20 and a positioning member for the current collector members. Consequently, in the welding step (step 5) of the manufacturing method described later, it becomes easier to stably abut the current collector members against the terminals (positive electrode terminal 30 and / or negative electrode terminal 40) and join them.

[0065] In this embodiment, the spacer 80 is a single component. However, as described in the modified example (4-1) below, the spacer 80 may be composed of multiple components. In this embodiment, the current collectors (positive electrode current collector 50 and / or negative electrode current collector 60) are placed on the support portions 85 and 86 of the spacer 80, thereby integrating (mechanically connecting) the two components. However, as described in the modified example (4-2) below, the two components can also be integrated by a different mechanism.

[0066] [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 1A) Case preparation step; (Step 1B) Electrode preparation step; (Step 2) Connection step; (Step 3) Assembly step; (Step 4) Insertion step; (Step 5) Welding step; (Step 6) Sealing step. However, the order of (Step 1A) Case preparation step and (Step 1B) Electrode preparation step is not particularly limited and may be reversed or approximately simultaneous. Also, the order of (Step 1A) Case preparation step and (Step 2) Connection step is not particularly limited and may be reversed or approximately simultaneous. Also, the order of (Step 2) Connection step and (Step 3) Assembly step is not particularly limited and may be reversed or approximately simultaneous. Furthermore, (Step 3) Assembly step is an optional step and may be omitted. In addition, the manufacturing method disclosed herein may include other steps at any stage. For example, after (Step 6) Sealing step, a step of pouring electrolyte into the case 10 may be included.

[0067] (Step 1A) In the case preparation process, the case body 12 and the sealing plate 14 are prepared before the (Step 4) insertion process. Specifically, a bottomed cylindrical case body 12 having a bottom wall 12a, side walls 12b and 12c and an opening 12h, and a sealing plate 14 that seals the opening 12h are prepared. The case body 12 and the sealing plate 14 may be purchased from a supplier, etc., or they can be manufactured in-house. Figure 6 is a schematic longitudinal cross-sectional view of an integrally molded product including the case body 12. Note that in Figure 6, the bottom wall 12a of the case body 12 is in an inverted position facing vertically upward, taking into consideration the workability in the (Step 5) welding process described later.

[0068] In the integrally molded product shown in Figure 6, terminals (positive terminal 30 and / or negative terminal 40) are attached to the bottom wall 12a of the case body 12. Preferably, the terminals are attached to the bottom wall 12a in an insulated state via an insulating member (in this case, a gasket 90). The method of attaching the terminals is not particularly limited. In this case, the terminals are attached to the bottom wall 12a together with the gasket 90 by insert molding (integral molding). That is, the case body 12 is prepared here as an integrally molded product integrated with the gasket 90 and the 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, or they may be attached to the bottom wall 12a via an adhesive layer (adhesive, etc.). Also, as described in the modified example (5) below, the terminals do not necessarily have to be attached to the bottom wall 12a beforehand; for example, they can be attached to the bottom wall 12a by an insertion process or welding process described later.

[0069] (Step 1B) In the electrode preparation 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. In one example, 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 in the longitudinal direction LD with the 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, the cylindrically wound electrode body (cylindrical body) is pressed into a flat shape, for example, to produce a flat electrode body 20. Then, multiple positive electrode tabs 22t are bundled together and integrated as a positive electrode tab group 27. Similarly, multiple negative electrode tabs 24t are bundled together and integrated as a negative electrode tab group 28.

[0070] (Step 2) In the connection step, the first current collector (positive electrode current collector 50 or negative electrode current collector 60) is electrically connected to the first electrode (positive electrode 22 or negative electrode 24) of the electrode body 20. That is, a conductive path is formed between the first electrode and the first current collector. In this embodiment, the first connection portion 51 of the positive electrode current collector 50 is joined to the positive electrode tab group 27 of the positive electrode 22, thereby electrically connecting the positive electrode current collector 50 to the positive electrode 22. Similarly, the first connection portion 61 of the negative electrode current collector 60 is joined to the negative electrode tab group 28 of the electrode body 20, thereby electrically connecting the negative electrode current collector 60 to the negative electrode 24. 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 joining by irradiation with an energy ray, such as ultrasonic welding, resistance welding, or laser welding. As a result, the electrode body 20 is integrated (mechanically connected) with the current collector. The electrode body 20 is then covered with an electrode body holder 29 (such as a resin sheet).

[0071] (Step 3) In the assembly process, after the connection process and before the insertion process (before inserting the electrode body 20 into the case body 12), the spacer 80 is assembled to the first current collector (positive electrode current collector 50 or negative electrode current collector 60). As described above, the spacer 80 of this embodiment has notches 85n and 86n (see Figure 5(A)), so the spacer 80 can be assembled to the first current collector by sliding (inserting) the spacer 80 from the side of the first current collector. As a result, the spacer 80 is integrated with the first current collector, and a combined object including the electrode body 20, the first current collector and the spacer 80 is produced. Figure 7 is a schematic longitudinal cross-sectional view of the combined object. Note that in Figure 7, as in Figure 6, the first current collector is in an inverted position facing upward in the vertical direction.

[0072] As described above, the spacer 80 of this embodiment has a pair of support portions 85 and 86. Therefore, when the spacer 80 is assembled to the first current collector (positive electrode current collector 50 or negative electrode current collector 60), as shown in Figure 7, the first connecting portion 51 of the positive electrode current collector 50 is fitted into the support portion 85 (specifically, the stepped portion 85s) of the spacer 80, and the electrode body 20 side of the first connecting portion 51 is supported by the support portion 85 (specifically, the stepped portion 85s). Also, the first connecting portion 61 of the negative electrode current collector 60 is fitted into the support portion 86 (specifically, the stepped portion 86s) of the spacer 80, and the electrode body 20 side of the first connecting portion 61 is supported by the support portion 86 (specifically, the stepped portion 86s). Furthermore, the positive electrode tab group 27 is inserted through the support portion 85 (specifically the through hole 85h) of the spacer 80, and the negative electrode tab group 28 is inserted through the support portion 86 (specifically the through hole 86h). As a result, a portion of the spacer 80 (here, the stepped portions 85s and 86s) is positioned between the first current collector and the electrode body 20. In addition, the second surface 89b of the spacer 80 is supported by the end face of the electrode body 20.

[0073] In this embodiment, in step 2 (connection step), the first current collector is electrically connected to the first electrode of the electrode body 20, and in step 3 (assembly step), the spacer 80 is attached to the first current collector. However, as described above, the order of these steps is not particularly limited. For example, the spacer 80 may be attached to the first current collector first, and then the first current collector may be electrically connected to the first electrode of the electrode body 20, in the opposite direction to this embodiment.

[0074] (Step 4) In the insertion step, after the connection step, the electrode body 20 is inserted into the case body 12, and at least a portion of the first current collector (positive electrode current collector 50 and negative electrode current collector 60) is placed in the first recess (first recess 30r or first recess 40r) of the first electrode terminal (positive electrode terminal 30 or negative electrode terminal 40). In this embodiment, the combined product shown in Figure 7, which was integrated in the (Step 3) assembly step, is inserted into the one-piece molded product shown in Figure 6, which was prepared in the (Step 1A) case preparation step. Specifically, the combined product shown in Figure 7 is inserted through the opening 12h of the case body 12 of the one-piece molded product shown in Figure 6, so that the side of the combined product shown in Figure 7 to which the current collector (positive electrode current collector 50 and / or negative electrode current collector 60) is attached faces the bottom wall 12a.

[0075] As described above, the combined object in Figure 7 includes an electrode body 20 and a spacer 80, and the spacer 80 is configured such that its outer peripheral edge abuts against or is close to the inner surface of the side walls (a pair of long side walls 12b and a pair of short side walls 12c) of the case body 12. Therefore, when the combined object is inserted into the case body 12 through the opening 12h, the spacer 80 moves towards the bottom wall 12a so as to follow the side walls 12b and 12c of the case body 12. The spacer 80 is positioned between the bottom wall 12a and the electrode body 20. By prefabricating the combined object as shown in Figure 7, it is easier to maintain the electrode body 20 in a horizontal position, and it is possible to prevent the electrode body 20 from being housed in the case body 12 in a tilted position or from getting caught on the side walls during movement. In other words, the spacer 80 in this embodiment can function as a guide member that guides the electrode body 20 to a desired position.

[0076] Furthermore, since the combined structure in Figure 7 also includes current collectors (positive electrode current collector 50 and negative electrode current collector 60), as the spacer 80 moves along the side walls 12b and 12c of the case body 12 toward the bottom wall 12a, the current collectors also move toward the bottom wall 12a. As a result, as shown in Figure 4, the columnar second connection portion 52 of the positive electrode current collector 50 is inserted into the first recess 30r of the positive electrode terminal 30, and at least a portion of the positive electrode current collector 50 is positioned within the first recess 30r of the positive electrode terminal 30. In this embodiment, the tip of the second connection portion 52 of the positive electrode current collector 50 abuts against the bottom surface 30b of the first recess 30r of the positive electrode terminal 30. Similarly, the columnar second connection portion 62 of the negative electrode current collector 60 is inserted into the first recess 40r of the negative electrode terminal 40, and at least a portion of the negative electrode current collector 60 is positioned within the first recess 40r of the negative electrode terminal 40. In this embodiment, the current collector can be stably inserted into the first recess of the terminal provided on the bottom wall 12a. That is, the spacer 80 in this embodiment can also function as a positioning member that guides the current collector to a desired joining position.

[0077] In this embodiment, as shown in Figures 6 and 7, the process is performed in an inverted position where the bottom wall 12a of the case body 12 faces upward in the vertical direction. However, if the electrode body 20 is heavy, for example, the process may be performed in a position where the side walls (a pair of long side walls 12b or a pair of short side walls 12c) are positioned vertically above and below, and the short or long side of the bottom wall 12a is horizontal.

[0078] (Step 5) In the welding process, after the insertion process, energy rays are irradiated from the first electrode terminal (positive electrode terminal 30 or negative electrode terminal 40) side to weld the portion of the first current collector (positive electrode current collector 50 or negative electrode current collector 60) that is positioned in the first recess (first recess 40r or first recess 40r) to the first electrode terminal. Figure 8 is an explanatory diagram of the welding process. Note that in Figure 8, the vicinity of the positive electrode terminal 30, which is a key part, is partially enlarged. Also, as in Figure 6, the bottom wall 12a is in an inverted position facing vertically upward.

[0079] In this embodiment, after the insertion process, the spacer 80 is positioned between the bottom wall 12a and the electrode body 20. As shown in Figure 8, the electrode body 20-side surface of the first current collector (positive electrode current collector 50) is supported vertically downward by the support portion 85 (specifically, the stepped portion 85s) of the spacer 80. Therefore, while the bottom wall 12a is inverted with the bottom wall 12a facing vertically upward, the electrode body 20 is pressed from the opening 12h side towards the bottom wall 12a side, as indicated by the arrow in Figure 8, thereby pressing the first current collector (positive electrode current collector 50) against the first electrode terminal (positive electrode terminal 30) via the spacer 80. This allows the positive electrode current collector 50 and the positive electrode terminal 30 to come into contact more precisely, enabling welding and joining in a suitably contacting state. Furthermore, it is preferable to provide a gap between the bottom wall 12a side surface of the first connection part 51 (top surface in Figure 8) and the portion of the positive terminal 30 facing the first connection part 51 (lower end of the inner flange 33 in Figure 8) while the tip of the second connection part 52 (upper end in Figure 8) is in contact with the positive terminal 30. This ensures that the tip of the second connection part 52 makes stable and reliable contact with the positive terminal 30.

[0080] The electrode body 20 may be pressed directly against the lower vertical end face (the end face opposite to the side where the first current collector is placed), or it may be pressed via another member (for example, the electrode body holder 29, another spacer, or the sealing plate 14, etc.).

[0081] Furthermore, in this embodiment, as shown in Figure 8, the inner surface of the bottom wall 12a and the spacer 80 do not come into contact during this process, but are in close proximity. That is, a small gap S1 is maintained between the inner surface of the bottom wall 12a and the part of the spacer 80 closest to the bottom wall 12a (the left end in Figure 8, near the short side wall 12c). As a result, the first current collector (positive electrode current collector 50) is effectively pressed against the first electrode terminal (positive electrode terminal 30) by the spacer 80.

[0082] Then, with the first current collector (positive electrode current collector 50) pressed against the first electrode terminal (positive electrode terminal 30), the contact points of the two members are welded together. More specifically, the portion of the positive electrode current collector 50 inserted into the first recess 30r is welded to the positive electrode terminal 30. In this embodiment, as shown in Figure 8, the first electrode terminal (positive electrode terminal 30) has a second recess 32r, and an energy ray (in this case, laser LB) is irradiated onto the bottom surface 30b of the second recess 32r. As a result, the tip of the second connection portion 52 of the positive electrode current collector 50 is welded to the bottom surface 30b of the first recess 30r of the positive electrode terminal 30. Irradiating the second recess 32r with an energy ray allows for a more stable bond between the positive electrode current collector 50 and the positive electrode terminal 30.

[0083] As described above, in this embodiment, the diameter Φ3 of the second connection portion 52 is larger than the diameter Φ2 of the second recess 32r of the positive electrode terminal 30 (Φ2 < Φ3, see Figure 4). As a result, even if the position of the second connection portion 52 shifts slightly in the XY plane when energy rays are irradiated into the second recess 32r, the positive electrode terminal 30 and the positive electrode current collector member 50 can be stably welded.

[0084] The type of energy ray used for irradiation is not particularly limited, but a laser is preferred. In some embodiments, it is preferable to perform through-welding by irradiating the case body 12 with an energy ray such as a laser from the outside (the outer surface side of the bottom wall 12a). Irradiating the case body 12 with an energy ray from the outside allows the joint to be visually inspected, making it easier to more stably join the first current collector member and the first electrode terminal. In this embodiment, as shown in Figure 4, the welded joint J (the part that melts and solidifies due to irradiation with an energy ray) is formed to penetrate the partition wall 30s of the positive electrode terminal 30 and reach the second connection part 52 of the positive electrode current collector member 50.

[0085] (Step 6) 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 joint between 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.

[0086] [Uses of energy storage devices] The energy storage device 100 can be used for various purposes, but it is particularly suitable for applications where a load may be applied to the terminals (positive terminal 30 and / or negative terminal 40) during use, such as a power source (driving power supply) for a motor mounted on a mobile vehicle (typically a passenger car, truck, or other vehicle). 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).

[0087] 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.

[0088] (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.

[0089] 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.

[0090] (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.

[0091] (2) Electrode body: For example, in the embodiment of FIG. 3 described above, the electrode body 20 was a wound electrode body. However, it is not limited to this. In a modified example, the electrode body 20 may 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 via a separator, for example. FIG. 9 is a longitudinal sectional view schematically showing the electrode body 120 according to the modified example. Note that FIG. 9 shows the state in the electrode body preparation step (step 1B), that is, the state before being housed in the case 10.

[0092] As shown in FIG. 9, the electrode body 120 of this modified example includes a plurality of positive electrode plates 122, a plurality of negative electrode plates 124, and a plurality of separators 126. The positive electrode plates 122 and the negative electrode plates 124 are stacked along the short side direction X. The positive electrode plate 122 includes a positive electrode active material layer 122a, and the negative electrode plate 124 includes a negative electrode active material layer 124a. In the vertical direction Z, the length of the negative electrode active material layer 124a is longer than the length of the positive electrode active material layer 122a. The length of the separator 126 is longer than the length of the negative electrode active material layer 124a. The separator 126 protrudes beyond the upper and lower sides of the negative electrode active material layer 124a, respectively. Note that the lower side in FIG. 9 is the side facing the bottom wall 12a of the case body 12 when housed in the case 10, and the upper side is the side facing the sealing plate 14 when housed in the case 10.

[0093] The separator 126 has a first protruding portion P1 protruding downward (toward the bottom wall 12a) from the lower end of the negative electrode active material layer 124a and a second protruding portion P2 protruding upward (toward the sealing plate 14) from the upper end of the negative electrode active material layer 124a. In this modified example, in the state where the separator 126 extends as shown in FIG. 9, it is preferable that the length D2 in the vertical direction Z of the second protruding portion P2 is longer than the length D1 in the vertical direction Z of the first protruding portion P1 (that is, D1 < D2). The ratio (D2 / D1) of the length D2 of the second protruding portion P2 to the length D1 of the first protruding portion P1 is preferably 1.2 or more, and more preferably 1.5 or more. Note that in the state where the electrode body 120 is housed in the case 10, the first protruding portion P1 and the second protruding portion P2 are in a folded state, respectively.

[0094] Also, the length T1 in the vertical direction Z of the electrode body 120 in the state where the separator 126 is extended (see FIG. 9) is preferably longer than the length T2 in the vertical direction Z of the inner dimension of the case 10 (not shown) (that is, T2 < T1). Further, at a position away from the terminals (the positive electrode terminal 30 and / or the negative electrode terminal 40) (for example, near the short side wall 12c), the length T1 in the vertical direction Z of the electrode body 120 is more preferably longer than the length T3 (not shown) obtained by subtracting the thickness of the spacer (the length in the vertical direction Z) from the above-mentioned length T2 (that is, T3 < T1). Furthermore, at a position away from the terminals (the positive electrode terminal 30 and / or the negative electrode terminal 40) (for example, near the short side wall 12c), the length T1 in the vertical direction Z of the electrode body 120 is even more preferably longer than the length T4 (not shown) obtained by subtracting the thickness of the electrode body holder 29 (for two upper and lower layers) from the above-mentioned length T3 (that is, T4 < T1).

[0095] When the length T1 of the electrode body 120 satisfies any of the above relationships, in the (step 4) insertion process, when the electrode body 120 is inserted into the inside of the case body 12, the first protruding portion P1 and / or the second protruding portion P2 of the electrode body 120 is folded along the inner surface of the case body 12. Thereby, the electrode body 120 can be preferably pressed against the bottom wall 12a of the case body 12, and in the (step 5) welding process, it becomes easier to make the first current collecting member abut against the first electrode terminal more stably.

[0096] (3) Current collecting member: For example, in the above-described embodiments of FIGS. 2 and 4, the second connection portion 52 of the positive electrode current collecting member 50 is arranged at a position that does not overlap with the positive electrode tab group 27 in a plan view in the XY plane (a position shifted from the positive electrode tab group 27). However, it is not limited to this. FIG. 10 is a view corresponding to FIG. 2 according to a modified example. As shown in FIG. 10, the power storage device 200 of this modified example has a positive electrode current collecting member 150. The positive electrode current collecting member 150 has a first connection portion 151 and a second connection portion 152. The positive electrode current collecting member 150 has a shape that is symmetric about the long side direction Y. The second connection portion 152 is arranged at a position that overlaps with the positive electrode tab group 27 of the electrode body 20 in a plan view in the XY plane.

[0097] (4) Spacer: (4-1) For example, in the embodiment shown in Figure 5 above, the spacer 80 was a single component. However, it is not limited to this. In modified examples, the spacer 80 may be composed of multiple components. The spacer may have, for example, a first part and a second part divided in the short-side direction X. In that case, in the (step 3) assembly step, the spacer may be assembled to the current collector (positive electrode current collector 50 and / or negative electrode current collector 60) by sandwiching the current collector (positive electrode current collector 50 and / or negative electrode current collector 60) from both sides in the short-side direction X between the first part and the second part of the spacer.

[0098] (4-2) In addition, in the embodiment described above, for example, current collectors (positive electrode current collector 50 and / or negative electrode current collector 60) were arranged on the support portions 85 and 86 of the spacer 80 so that the two members were integrated (mechanically connected) and both could move toward the bottom wall 12a. However, it is not limited to this. The term "integration" as used herein may include, for example, all of the following embodiments. (4-2a) A configuration in which the spacer has a through hole, and a part of the current collector (for example, a columnar second connecting part) is inserted through the through hole of the spacer. (4-2b) A configuration in which a recess is provided on the upper or lower surface of the spacer, and a part of the current collector (for example, a flange portion such as the first connection portion described above) is fitted into the recess of the spacer. (4-2c) A configuration in which a fixing claw portion is provided on the upper or lower surface of the spacer, and the current collector member is fixed by hooking a part of the current collector member (for example, a flange portion such as the first connection portion described above) with the said claw portion.

[0099] (4-3) In addition, for example, in the embodiment described above, the base portion 89 of the spacer 80 was flat. However, it is not limited to this. In the modified example shown in (3) above in Figure 10, the spacer 180 has a thin-walled region A1 that is provided on the periphery of the terminals (positive terminal 30 and / or negative terminal 40) and is relatively thin, and a thick-walled region A2 that is provided at a position away from the terminals (in this case, near a pair of short side walls 12c) and is relatively thick. In the modified example, by having the thick-walled region A2, 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 electrode body 20 can be supported by the bottom wall 12a via the thick-walled region A2. Therefore, damage to the conductive path, such as the positive electrode tab group 27 and / or the negative electrode tab group 28, or the joint between the positive electrode tab group 27 and the positive electrode current collector 50 and / or the joint between the negative electrode tab group 28 and the negative electrode current collector 60, can be effectively suppressed due to the weight of the electrode body 20.

[0100] (4-4) In addition, for example, in the embodiment described above, the spacer 80 functioned as a positioning member for the current collector (positive electrode current collector 50 and / or negative electrode current collector 60). However, the method of positioning the current collector is not limited to this. The spacer 80 does not have to function as a positioning member. In a modified example, the electrode holder 29 may function as a positioning member for the current collector. In this case, it is preferable that the outer edge of the electrode body 20 enclosed in the electrode holder 29 abuts against or is close to the inner surface of the side wall of the case body 12. The gap between the outer edge of the electrode body 20 enclosed in the electrode holder 29 and the side wall of the case body 12 (the difference between the inner dimensions of the case body 12 and the outer dimensions of the electrode holder 29) is preferably 1 mm or less, more preferably 0.8 mm or less, and even more preferably 0.5 mm or less. Furthermore, it is preferable that the electrode holder 29 has an end through-hole on the side where the current collecting members (positive electrode current collecting member 50 and / or negative electrode current collecting member 60) are arranged, and that the current collecting member (more specifically, the second connecting portion inserted into the through-hole of the terminal) passes through the end through-hole.

[0101] (5) Terminal installation: For example, in the embodiment described above, as shown in Figure 6, 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 1A) case preparation step. However, the invention is not limited to this. The terminals can also be attached to the bottom wall 12a in the (Step 5) welding step, for example. In one example, first, in the (Step 4) insertion step, the terminal exit holes 18 and 19 of the bottom wall 12a are sandwiched between the terminals (positive terminal 30 and / or negative terminal 40) and the current collector members (positive current collector member 50 and / or negative current collector member 60) from both the inside and outside of the case body 12, and at least a part of the current collector members is placed in the first recesses 30r and 40r of the terminals. Then, in the (Step 5) welding step, the terminals and the current collector members are welded together. This allows the terminals to be attached to the bottom wall 12a (via an insulating member, if necessary) at approximately the same time as forming the welded joint J.

[0102] 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 via a first current collector, 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 that seals the opening of the case body, wherein the first electrode terminal is attached to the bottom wall of the case body and has a first recess on the inside of the case body, and the first current collector is at least a part of the above A method for manufacturing an energy storage device, comprising: a connection step of electrically connecting the first current collector member to the first electrode, wherein the first current collector member is placed in a first recess, and the portion of the electrode body placed in the first recess is welded to the first electrode terminal; an insertion step of inserting the electrode body into the case body after the connection step and placing at least a portion of the first current collector member in the first recess of the first electrode terminal; and a welding step of irradiating the portion of the first current collector member placed in the first recess with the first electrode terminal after the insertion step by irradiating it with an energy ray from the first electrode terminal side. Item 2: The manufacturing method according to Item 1, wherein in the welding process, a spacer is placed between the bottom wall and the electrode body, and the electrode body is pressed towards the bottom wall, thereby joining the first current collector member and the first electrode terminal while the first current collector member is pressed against the first electrode terminal via the spacer. Item 3: The manufacturing method according to Item 2, wherein in the welding process, the electrode body side surface of the first current collector is supported by the spacer. Item 4: The manufacturing method according to any one of items 1 to 3, further comprising a case preparation step of preparing the case body on which the first electrode terminal is attached to the bottom wall, prior to the insertion step. Item 5: The manufacturing method according to item 2 or 3, wherein the spacer is integrated with the first current collector before the insertion step. Item 6: The manufacturing method according to item 2 or 3, wherein a portion of the spacer is placed between the first current collector and the electrode body after the connection step and before the insertion step. Item 7: The manufacturing method according to any one of items 1 to 6, wherein the first electrode terminal further has a second recess on its outer surface at a position opposite to the first recess, and in the welding process, the energy ray is irradiated onto the bottom surface of the second recess. 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 via a first current collector, 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 that seals the opening of the case body, the first electrode terminal being attached to the bottom wall of the case body and having a first recess on the inside of the case body, and at least a portion of the first current collector being disposed within the first recess, with the portion disposed within the first recess being welded to the first electrode terminal. Item 9: The energy storage device according to item 8, further comprising a spacer disposed between the bottom wall and the electrode body, wherein the spacer has a portion disposed between the first current collector and the electrode body. Item 10: The energy storage device according to Item 9, wherein the spacer is integrated with the first current collector. Item 11: The energy storage device according to any one of items 8 to 10, wherein the first electrode terminal further has a second recess on its outer surface opposite to the first recess, and the welded joint between the first current collector and the first electrode terminal extends from the bottom surface of the second recess to the bottom surface of the first recess and further into the interior of the first current collector. [Explanation of Symbols]

[0103] 10 cases 12 Case body 12a Bottom wall 14 Sealing plate 20 Electrode body 22 Positive electrode (1st electrode / 2nd electrode) 24 Negative electrode (1st electrode / 2nd electrode) 27 Positive electrode tab group 30 Positive terminal (first electrode terminal) 30r First recess 40 Negative terminal 50 Positive electrode current collector (first current collector) 60 Negative electrode current collector 80 Spacer 100 Energy storage devices

Claims

1. An electrode body including a first electrode and a second electrode, A case for housing the electrode body, A first electrode terminal electrically connected to the first electrode via a 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, The first electrode terminal is attached to the bottom wall of the case body and has a first recess on the inside side of the case body. The first current collector member is positioned in the first recess, at least a portion of which is welded to the first electrode terminal, A connection step of electrically connecting the first current collector to the first electrode, After the connection step, the insertion step involves inserting the electrode body into the case body and placing at least a portion of the first current collector in the first recess of the first electrode terminal, After the insertion step, a welding step is performed in which an energy ray is irradiated from the first electrode terminal side to weld the portion of the first current collector member that is positioned in the first recess to the first electrode terminal, A method for manufacturing an energy storage device, including the method described above.

2. In the welding process described above, a spacer is placed between the bottom wall and the electrode body. By pressing the electrode body toward the bottom wall, the first current collector is pressed against the first electrode terminal via the spacer, thereby joining the first current collector and the first electrode terminal. The manufacturing method according to claim 1.

3. In the welding process, the electrode side surface of the first current collector is supported by the spacer. The manufacturing method according to claim 2.

4. Prior to the insertion step, the process further includes a case preparation step of preparing the case body on which the first electrode terminal is attached to the bottom wall. The manufacturing method according to any one of claims 1 to 3.

5. The spacer is integrated with the first current collector before the insertion step. The manufacturing method according to claim 2 or 3.

6. After the connection step and before the insertion step, a portion of the spacer is placed between the first current collector and the electrode body. The manufacturing method according to claim 2 or 3.

7. The first electrode terminal further has a second recess on its outer surface at a position opposite to the first recess, In the welding process, the energy ray is irradiated onto the bottom surface of the second recess. The manufacturing method according to any one of claims 1 to 3.

8. An electrode body including a first electrode and a second electrode, A case for housing the electrode body, A first electrode terminal electrically connected to the first electrode via a 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, The first electrode terminal is attached to the bottom wall of the case body and has a first recess on the inside side of the case body. The first current collector member is positioned in the first recess, at least a portion of which is welded to the first electrode terminal. Energy storage device.

9. The system further comprises a spacer disposed between the bottom wall and the electrode body, The spacer has a portion that is positioned between the first current collector and the electrode body. The energy storage device according to claim 8.

10. The spacer is integrated with the first current collector. The energy storage device according to claim 9.

11. The first electrode terminal further has a second recess on its outer surface at a position opposite to the first recess, The welded joint between the first current collector and the first electrode terminal extends from the bottom surface of the second recess to the bottom surface of the first recess, and further extends into the interior of the first current collector. The energy storage device according to any one of claims 8 to 10.

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