Manufacturing method of electricity storage device and fixing jig

Abstract

To provide a manufacturing method for a power storage device, in which laser passing does not occur easily.SOLUTION: The present invention discloses a manufacturing method for a power storage device 100, the power storage device including a case body 12, a sealing plate 14, and an electrode body 20. The manufacturing method includes: a jig preparation step of preparing a fixing jig 200 that includes a pair of long side clamp portions 231, 232 applying a first load P1 against the case body 12 and the sealing plate 14 from a side of a long side wall 12b of the case body 12 to hold the case body 12 and the sealing plate 14, and elastic portions 240 which are provided on respective faces of the pair of long side clamp portions 231, 232 on a side opposing an assembly 100A and which apply a second load P2 less than the first load P1 against the assembly 100A; an assembly fixing step of fixing the assembly 100A by the fixing jig 200; and a laser welding step of welding the sealing plate 14 and the case body 12 by laser while the assembly 100A is fixed.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing an electricity storage device and a fixing jig. [Background technology]

[0002] Conventionally, there has been known an electricity storage device including a case body having a rectangular bottom wall, a pair of long side walls extending from a long side of the bottom wall and facing each other, a pair of short side walls extending from a short side of the bottom wall and facing each other, and an opening facing the bottom wall, a rectangular sealing plate (lid body) disposed in the opening of the case body and having an outer peripheral edge portion laser welded to an inner peripheral edge portion of the opening of the case body, and an electrode body housed in the case body. This type of electricity storage device is manufactured, for example, by housing the electrode body inside the case body and placing the sealing plate in the opening of the case body, and then laser welding the sealing plate and the case body.

[0003] Related prior art documents include Patent Documents 1 to 4. For example, Patent Document 1 describes a method in which the upper end of the long side wall of the case body is pressed and fixed with a pair of block-shaped clamps (jigs), and in this state, the sealing plate and the case body are laser welded together. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-113160 A [Patent Document 2] JP 2013-187087 A [Patent Document 3] JP 2019-186156 A [Patent Document 4] Patent Publication No. 2021-086749 Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, the capacity of batteries mounted on vehicles and the like has been increasing, and the size of the electrode body has been increasing. As a result, when the case body and the sealing plate become longer, the processing errors (tolerance dimensions and straightness) of the case body and the sealing plate become larger, especially in the long side direction. As a result, according to the study by the present inventor, when the case body and the sealing plate are combined, a gap of up to about 0.094 mm may be generated between the long side wall of the case body and the sealing plate. If there is a large gap between the case body and the sealing plate, there is a risk that the laser light will enter the case body through the gap during laser welding, which is called laser leakage. If the laser light that has entered the case body due to laser leakage hits the electrode body, the electrode body may be burned or internally shorted, resulting in damage.

[0006] The present invention has been made in view of the above circumstances, and has an object to provide a manufacturing method and a fixing jig for an electricity storage device in which laser welding is less likely to result in laser voids. [Means for solving the problem]

[0007] The present invention provides a method for manufacturing an electricity storage device comprising: a case body having a rectangular bottom wall, a pair of long side walls extending from a long side of the bottom wall and facing each other, a pair of short side walls extending from a short side of the bottom wall and facing each other, and an opening facing the bottom wall, a rectangular sealing plate disposed within the opening of the case body and having an outer peripheral edge laser welded to an inner peripheral edge of the opening of the case body, and an electrode body contained in the case body. The manufacturing method includes an assembly fabrication process for fabricating an assembly by accommodating the electrode body inside the case body and placing the sealing plate in the opening of the case body; a jig preparation process for preparing a fixing jig that includes a pair of long side clamping portions that apply a first load to the case body and the sealing plate from the long side wall side of the case body to clamp the case body and the sealing plate, and one or more elastic portions that are provided on respective surfaces of the pair of long side clamping portions facing the assembly and apply a second load to the assembly that is smaller than the first load; an assembly fixing process for fixing the assembly with the fixing jig; and a laser welding process for laser welding the sealing plate to the case body while the assembly is fixed by the fixing jig.

[0008] In the above manufacturing method, a fixing jig having elastic parts on a pair of long side clamp parts is prepared in the jig preparation step, and the assembly is fixed with the fixing jig in the assembly fixing step. The elastic parts then act to press the long side walls of the case body toward the sealing plate at the locations where there is a gap between the long side walls and the sealing plate. As a result, compared to the case where a conventional fixing jig not having elastic parts is used, the long side walls can be brought into good contact with the sealing plate relatively, making the gap smaller. Therefore, the occurrence of laser weld failure in the laser welding step can be suppressed. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view that illustrates a schematic diagram of an electricity accumulation device according to an embodiment. [Diagram 2] FIG. 2 is a schematic vertical cross-sectional view taken along line II-II in FIG. [Diagram 3] FIG. 3 is a schematic plan view illustrating the assembly fixing step. [Figure 4] FIG. 4 is a schematic vertical cross-sectional view taken along line IV-IV in FIG. [Diagram 5] 5A and 5B are plan views for explaining the function of the elastic portion, in which FIG. 5A shows an assembly manufacturing step and FIG. 5B shows an assembly fixing step. [Figure 6] FIG. 6 is a schematic vertical cross-sectional view of the vicinity of an elastic portion according to a first modified example. [Figure 7] FIG. 7(A) is a view corresponding to FIG. 6 according to the second modified example, and FIG. 7(B) is a view corresponding to FIG. 5(B) according to the second modified example. [Figure 8] FIG. 8(A) is a view corresponding to FIG. 6 according to the third modified example, and FIG. 8(B) is a view corresponding to FIG. 5(B) according to the third modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, some preferred embodiments of the technology disclosed herein will be described with reference to the drawings. It should be noted that matters other than those specifically mentioned in this specification and necessary for implementing the technology disclosed herein (for example, the general configuration and manufacturing process of an electricity storage device that does not characterize the technology disclosed herein) can be understood as design matters of a person skilled in the art based on the conventional technology in the field. The technology disclosed herein can be implemented based on the contents disclosed in this specification and the technical common sense in the field. It should be noted that the expression "A to B" indicating a range in this specification includes the meaning of "A or more and B or less", as well as "greater than A" and "less than B".

[0011] <Electricity storage device> FIG. 1 is a schematic perspective view of the power storage device 100. FIG. 2 is a schematic longitudinal sectional view taken along line II-II in FIG. 1. In the following description, the symbols L, R, F, Rr, U, and D in the drawings represent left, right, front, rear, top, and bottom. In the drawings, the symbol X represents the short side direction (thickness direction) of the power storage device 100, the symbol Y represents the long side direction perpendicular to the short side direction, and the symbol Z represents the height direction of the power storage device 100. However, these are merely directions for the sake of convenience in the description, and do not limit the installation form of the power storage device 100 in any way.

[0012] The power storage device 100 may be, for example, a secondary battery such as a lithium ion secondary battery or a nickel-hydrogen battery, or may be a lithium ion capacitor or an electric double layer capacitor, etc. Here, the power storage device 100 is a secondary battery, specifically a lithium ion secondary battery.

[0013] As shown in Fig. 2, the electricity storage device 100 includes a battery case 10 and an electrode assembly 20. Although not shown in the figure, the electricity storage device 100 further includes a nonaqueous electrolyte. As the nonaqueous electrolyte, any electrolyte used in a general nonaqueous electrolyte secondary battery (e.g., a lithium ion secondary battery) can be used without any particular limitation. However, in other embodiments, the electrolyte may be in a solid state (solid electrolyte) and integrated with the electrode assembly 20.

[0014] The battery case 10 is a container that contains the electrode assembly 20 and the non-aqueous electrolyte. As shown in FIG. 1, the battery case 10 has a flat, bottomed rectangular parallelepiped (rectangular) outer shape. The material of the battery case 10 may be the same as that conventionally used, and is not particularly limited. The battery case 10 is made of metal, and is preferably made of, for example, aluminum, aluminum alloy, iron, iron alloy, or the like. The battery case 10 is made of aluminum here. As shown in FIG. 2, the battery case 10 includes a case body 12 and a sealing plate (lid) 14.

[0015] The case body 12 has a bottom and is a rectangular cylinder. As shown in FIG. 1, the case body 12 includes a rectangular bottom wall 12a, a pair of long side walls 12b extending from the long sides of the bottom wall 12a and facing each other, a pair of short side walls 12c extending from the short sides of the bottom wall 12a and facing each other, and an opening 12h (see FIG. 2) facing the bottom wall 12a. The thickness (plate thickness) of the long side wall 12b and the short side wall 12c is typically 1 mm or less, for example, 0.3 to 0.5 mm. In the large-capacity electricity storage device 100, the length of the long side wall 12b in the long side direction Y can be 10 cm or more, 20 cm or more, or 30 cm or more. The length of the short side wall 12c in the short side direction X can be 1 / 3 or less, 1 / 4 or less, 1 / 5 or less, or 1 / 6 or less of the length of the long side wall 12b in the long side direction Y. The long side walls 12b have a larger area than the short side walls 12c. The opening 12h is defined by the ends of the pair of long side walls 12b facing the sealing plate 14 and the ends of the pair of short side walls 12c facing the sealing plate 14. The opening 12h is rectangular.

[0016] In this specification, the term "rectangular" includes not only a perfect rectangular shape (rectangular shape) but also a shape in which the corners connecting the long and short sides of the rectangle are rounded, a shape in which the corners are notched, etc. In the following description, the opening 12h and sealing plate 14 side of the case body 12 may be referred to as "upper", and the bottom wall 12a side of the case body 12 may be referred to as "lower".

[0017] The sealing plate 14 is a rectangular plate-like member that seals the opening 12h. As shown in FIG. 2, the sealing plate 14 is disposed in the opening 12h of the case body 12. The sealing plate 14 faces the bottom wall 12a of the case body 12. In a plan view, the outer shape of the sealing plate 14 is smaller than the opening 12h. The thickness (plate thickness) of the sealing plate 14 is typically thicker than the long side wall 12b, for example, 0.5 to 5 mm, 1 to 2 mm. The outer peripheral edge of the sealing plate 14 is laser welded to the inner peripheral edge of the opening 12h of the case body 12 over the entire circumference. A laser weld W is formed over the entire circumference of the outer peripheral edge of the sealing plate 14. This allows the battery case 10 to be integrated and hermetically sealed (sealed). Note that the laser weld W is not shown in FIG. 1.

[0018] As shown in Figs. 1 and 2, a positive electrode terminal 30 and a negative electrode terminal 40 are attached to the sealing plate 14. The positive electrode terminal 30 and the negative electrode terminal 40 are fixed to the sealing plate 14 by crimping. The positive electrode terminal 30 and the negative electrode terminal 40 are insulated from the sealing plate 14 by an insulating member (not shown). As shown in Fig. 2, the positive electrode terminal 30 is electrically connected to the positive electrode of the electrode body 20 via a positive electrode current collector 50 inside the battery case 10. The negative electrode terminal 40 is electrically connected to the negative electrode of the electrode body 20 via a negative electrode current collector 60 inside the battery case 10.

[0019] The electrode body 20 is accommodated inside the battery case 10 as shown in FIG. 2. The electrode body 20 may be the same as a conventional one and is not particularly limited. Although not shown, the electrode body 20 has a positive electrode and a negative electrode. The electrode body 20 is a flat wound electrode body in which a strip-shaped positive electrode and a strip-shaped negative electrode are stacked in an insulated state via a strip-shaped separator and wound in the longitudinal direction around a winding axis. However, in other embodiments, the electrode body 20 may be a laminated electrode body in which a rectangular positive electrode sheet and a rectangular negative electrode sheet are stacked in an insulated state.

[0020] The electrode body 20 is housed inside the battery case 10 with the winding axis being approximately parallel to the bottom wall 12a and the sealing plate 14 and approximately perpendicular to the long side wall 12b and the short side wall 12c. The electrode body 20 has a pair of wide surfaces 20f (see FIG. 4) with flat outer surfaces. The wide surfaces 20f of the electrode body 20 abut against the long side wall 12b of the case body 12. Therefore, the portion of the long side wall 12b abutting against the wide surface 20f of the electrode body 20 is unlikely to bend even when a load is applied. The height (length in the height direction Z) L1 from the upper end of the long side wall 12b to the upper end of the wide surface 20f of the electrode body 20 is about 20 mm here. Meanwhile, at the upper end (part of height L1) of the long side wall 12b, the electrode body 20 is separated from the long side wall 12b. Therefore, the upper end of the long side wall 12b is likely to bend (easily deformed) when a load is applied.

[0021] As shown in FIG. 2, a positive electrode current collecting part 22 is provided at one end of the electrode body 20 in the winding axis direction (long side direction Y in FIG. 2). A negative electrode current collecting part 24 is provided at the other end. A positive electrode current collecting member 50 is attached to the positive electrode current collecting part 22. A negative electrode current collecting member 60 is attached to the negative electrode current collecting part 24. The positive electrode current collecting member 50 constitutes a conductive path that electrically connects the positive electrode terminal 30 and the positive electrode of the electrode body 20. The negative electrode current collecting member 60 constitutes a conductive path that electrically connects the negative electrode terminal 40 and the negative electrode of the electrode body 20.

[0022] <Method of manufacturing electricity storage device> The above-described power storage device 100 can be manufactured by a manufacturing method including, for example, an assembly fabrication step (S1A), a jig preparation step (S1B), an assembly fixing step (S2), a laser welding step (S3), and a liquid injection step (S4). The order of the assembly fabrication step (S1A) and the jig preparation step (S1B) is not particularly limited. The liquid injection step is not essential, and can be omitted, for example, when a solid electrolyte is used instead of a nonaqueous electrolyte. The manufacturing method of this embodiment may include other steps than the above at any stage. FIG. 3 is a schematic plan view illustrating the assembly fixing step (S2). FIG. 4 is a schematic vertical cross-sectional view taken along the line IV-IV in FIG. 3. Each step will be described below with reference to the drawings as appropriate.

[0023] In the (S1A) assembly preparation step, an assembly 100A (see Figs. 3 and 4) is prepared. Specifically, first, the above-mentioned case body 12, sealing plate 14, and electrode body 20 are prepared. Next, the sealing plate 14 and the electrode body 20 are integrated. More specifically, the positive electrode terminal 30 and the negative electrode terminal 40 are attached to the sealing plate 14 by crimping. A positive electrode current collecting member 50 is attached to the positive electrode current collecting portion 22 of the electrode body 20, and a negative electrode current collecting member 60 is attached to the negative electrode current collecting portion 24. The positive electrode current collecting member 50 is welded to the positive electrode terminal 30, and the negative electrode current collecting member 60 is welded to the negative electrode terminal 40.

[0024] Next, the electrode body 20 is housed inside the case body 12, and the sealing plate 14 is placed in the opening 12h of the case body 12 to prepare the assembly 100A. Specifically, the electrode body 20 fixed to the sealing plate 14 is inserted into the internal space of the case body 12 through the opening 12h. As a result, the sealing plate 14 is inserted into the case body 12, and the outer peripheral edge of the sealing plate 14 faces the inner peripheral edge of the opening 12h of the case body 12. Note that the "assembly" here refers to an assembly that includes the case body 12, the sealing plate 14, and the electrode body 20, and in which the case body 12 and the sealing plate 14 are in an unsealed state, that is, an intermediate product before laser welding is performed.

[0025] In addition, the outer shape of the sealing plate 14 is usually formed smaller than the opening 12h of the case body 12. This is to suppress the generation of metal powder due to friction between the metal case body 12 and the metal sealing plate 14 when the sealing plate 14 is placed in the opening 12h of the case body 12 in this process. Furthermore, according to the knowledge of the present inventor, although the processing accuracy is specified for each of the case body 12 and the sealing plate 14, processing errors (tolerance dimensions, straightness) may occur within that range. For example, the case body 12 may have a variation (deviation) in plate thickness, stress bending during the formation of the opening 12h (during trim cutting), waviness, etc. In addition, the sealing plate 14 may have a variation (deviation) in plate thickness, stress bending during cutting, waviness, crushing and expansion during crimping of the positive electrode terminal 30 and the negative electrode terminal 40, etc. Due to these processing errors, in the assembly 100A not fixed by the fixing jig 200 described later, a large gap G (see FIG. 5(A)) of up to approximately 0.094 mm may occur between the long side wall 12b of the case body 12 and the sealing plate 14.

[0026] In the jig preparation step (S1B), a fixing jig 200 as shown in Figs. 3 and 4 is prepared. The fixing jig 200 is for clamping and pressing and fixing the case body 12 and the sealing plate 14 of the assembly 100A when welding the case body 12 and the sealing plate 14 in the laser welding step (S3) described later. The fixing jig 200 of this embodiment includes a housing 210, a fixing member 221, first to third movable members 222, 223, 224, a pair of long side clamping parts 231, 232, a pair of short side clamping parts 233, 234, and a plurality of elastic parts 240, as shown in Fig. 3. The assembly 100A is arranged in an area defined by the pair of long side clamping parts 231, 232 and the pair of short side clamping parts 233, 234. It should be noted that the second and third movable members 223, 224 and the pair of short side clamp portions 233, 234 are not essential and may be omitted in other embodiments.

[0027] 3, the housing 210 includes a rectangular base portion 215, a first standing portion 211 and a second standing portion 212 extending from a long side of the rectangular base portion 215 and facing each other, and a third standing portion 213 and a fourth standing portion 214 extending from a short side of the rectangular base portion 215 and facing each other. The housing 210 is made of metal, for example, molybdenum, copper, stainless steel, or the like. An insertion hole H is formed in the second standing portion 212. The insertion hole H is a bearing (bush) of the first movable member 222 described later. The shaft portion SM of the first movable member 222 is inserted into the insertion hole H.

[0028] The fixed member 221 is supported by the first standing portion 211 as shown in Figs. 3 and 4. The fixed member 221 is made of metal here, for example, the same metal as the housing 210. The fixed member 221 is fixed to the first standing portion 211 of the housing 210. The fixed member 221 is configured so as not to be movable in the short side direction X. The fixed member 221 is provided with a long side clamp portion 231, which will be described later.

[0029] As shown in FIG. 3 and FIG. 4, the first movable member 222 is supported by the second standing portion 212 of the housing 210. The first movable member 222 is made of metal here, for example, the same metal as the housing 210. The first movable member 222 has an axis portion SM. The axis portion SM is a round bar-shaped shaft. The axis portion SM is inserted into the insertion hole H of the second standing portion 212. Unlike the fixed member 221, the first movable member 222 is configured to be movable in the short side direction X. Specifically, the first movable member 222 has two biasing springs ES1. The first movable member 222 is attached to the second standing portion 212 of the housing 210 via the biasing spring ES1. The biasing spring ES1 is, for example, a coil spring (compression spring).

[0030] The first movable member 222 is biased by the biasing spring ES1 toward the opposing first standing portion 211 (the front side in FIG. 3) as shown by the arrow A2 in FIG. 3. This allows the first movable member 222 to move in a direction toward the second standing portion 212 and a direction away from the second standing portion 212 within the range of elastic deformation of the biasing spring ES1. The first movable member 222 is provided with a long side clamp portion 232, which will be described later.

[0031] As shown in FIG. 3, the second movable member 223 is supported by the third standing portion 213 of the housing 210. The third movable member 224 is supported by the fourth standing portion 214 of the housing 210. The second and third movable members 223 and 224 are made of metal, for example, the same metal as the housing 210. The second and third movable members 223 and 224 are provided symmetrically in the long side direction Y. The second and third movable members 223 and 224 are each configured to be movable in the long side direction Y. Specifically, the second and third movable members 223 and 224 each include a biasing spring ES2. The second and third movable members 223 and 224 are each attached to the third standing portion 213 or the fourth standing portion 214 of the housing 210 via the biasing spring ES2. The biasing spring ES2 is, for example, a coil spring.

[0032] The second movable member 223 is biased by the biasing spring ES2 toward the opposing fourth standing portion 214 (the right side in FIG. 3) as shown by the arrow A3 in FIG. 3. As a result, the second movable member 223 is configured to be movable in a direction approaching the third standing portion 213 and a direction away from the third standing portion 213 within the range of elastic deformation of the biasing spring ES2. The second movable member 223 is provided with a short side clamping portion 233, which will be described later. The third movable member 224 is biased by the biasing spring ES2 toward the opposing third standing portion 213 (the left side in FIG. 3) as shown by the arrow A4 in FIG. 3. As a result, the third movable member 224 is configured to be movable in a direction approaching the fourth standing portion 214 and a direction away from the fourth standing portion 214 within the range of elastic deformation of the biasing spring ES2. The third movable member 224 is provided with a short side clamping portion 234, which will be described later.

[0033] As shown in FIG. 3, the pair of long side clamping parts 231, 232 are configured to apply a first load P1 (see FIG. 4) to the pair of long side walls 12b of the assembly 100A and the long side of the sealing plate 14 to clamp the long side wall 12b and the sealing plate 14. In detail, one long side clamping part 231 is provided on the surface of the fixed member 221 facing the assembly 100A. The other long side clamping part 232 is provided on the surface of the first movable member 222 facing the assembly 100A. The pair of long side clamping parts 231, 232 are provided so as to face the long side walls 12b of the assembly 100A. The pair of long side clamping parts 231, 232 are disposed opposite to each other in the short side direction X. The pair of long side clamping parts 231, 232 are provided symmetrically in the short side direction X across the assembly 100A.

[0034] The pair of long side clamping parts 231, 232 are made of a hard material that does not have elasticity. The pair of long side clamping parts 231, 232 are made of metal here. The pair of long side clamping parts 231, 232 are preferably made of a metal material with high thermal conductivity and hardness, such as beryllium copper. The long side clamping part 231 is a member (a different material) different from the fixed member 221 here, and is fixed to the fixed member 221 by, for example, screw fastening. Similarly, the long side clamping part 232 is a member (a different material) different from the first movable member 222 here, and is fixed to the first movable member 222 by, for example, screw fastening. However, in other embodiments, the long side clamping part 231 may be formed integrally with the fixed member 221, and the long side clamping part 232 may be formed integrally with the first movable member 222.

[0035] The pressure (first load P1) with which the pair of long side clamping parts 231, 232 clamp the long side wall 12b of the assembly 100A and the sealing plate 14 is a design item that should be appropriately changed depending on, for example, the material and thickness of the long side wall 12b of the case body 12. Although not particularly limited, when the case body 12 is made of aluminum with a thickness of 1 mm or less, the first load P1 is preferably about 100 N or more, for example, about 200 to 300 N. This makes it possible to firmly fix the long side wall 12b and the long side of the sealing plate 14 in the assembly fixing step (S2) described later. The first load P1 can be adjusted by the spring constant of the biasing spring ES1 (biasing force A2 in FIG. 3).

[0036] As shown in FIG. 3, the pair of long side clamping parts 231, 232 each extend along the long side direction Y. The length of the pair of long side clamping parts 231, 232 in the long side direction Y is preferably approximately the same as or longer than the long side wall 12b of the assembly 100A. As can be seen from FIG. 3 and FIG. 4, the pair of long side clamping parts 231, 232 each have an approximately rectangular parallelepiped shape. The pair of long side clamping parts 231, 232 each protrude toward the assembly 100A more than the fixed member 221 or the first movable member 222. Here, the pair of long side clamping parts 231, 232 are configured to directly contact (abut) the long side wall 12b of the assembly 100A to press the assembly 100A. However, as described in a modified example described later, the pair of long side clamping parts 231, 232 may be configured to indirectly press the assembly 100A with another member interposed therebetween.

[0037] As shown in FIG. 4, in the height direction Z, the pair of long side clamping parts 231, 232 are provided so as to press the upper end (end on the sealing plate 14 side) of the long side wall 12b of the assembly 100A with a length L2. The length L2 is shorter than the height L1 (here, 20 mm) from the upper end of the case body 12 to the upper end of the wide surface 20f of the electrode body 20. That is, the pair of long side clamping parts 231, 232 are configured so as not to press the lower side (bottom wall 12a side) of the upper end of the long side wall 12b. The length L2 is typically larger than the thickness of the sealing plate 14, and is preferably, for example, 5 mm or more (1 / 4 or more of the length L1) and 10 mm or less (1 / 2 or less of the length L1). Here, the length L2 is 8 to 10 mm. Here, the distance D1 between the upper end of the case body 12 and the upper ends of the long side clamping parts 231, 232 is 1 mm.

[0038] The elastic parts 240 are provided on each of the pair of long side clamp parts 231, 232. As shown in FIG. 3, the elastic parts 240 are provided on the surface facing the long side wall 12b of the assembly 100A. As shown in FIG. 4, the elastic parts 240 are configured to apply a second load P2 smaller than the first load P1 to the long side wall 12b of the assembly 100A. Although details will be described later, by providing the elastic parts 240 on the pair of long side clamp parts 231, 232, even if a large gap G (see FIG. 5(A)) is opened between the long side wall 12b and the sealing plate 14 in the state of the assembly 100A, the gap G can be reduced by bringing the long side wall 12b of the case body 12 closer to the sealing plate 14 in the assembly fixing step (S2) described later.

[0039] Here, each of the elastic parts 240 includes an abutment part C that abuts against the long side wall 12b of the assembly 100A and presses the long side wall 12b, and a compression spring S that is attached to the abutment part C and expands and contracts in a direction approaching the long side wall 12b and a direction away from the long side wall 12b (short side direction X in FIG. 3). The abutment part C has a convex outer shape. The abutment part C is supported by the compression spring S in a state in which the tip part protrudes from the long side clamp parts 231, 232 to the assembly 100A side before the assembly 100A is clamped by the pair of long side clamp parts 231, 232 (before clamping). The abutment part C is configured to be movable in a direction approaching the long side wall 12b of the assembly 100A and a direction away from the long side wall 12b of the assembly 100A (short side direction X in FIG. 3) within the range of elastic deformation of the compression spring S. The contact portion C is a pressure pin in this embodiment. The compression spring S is housed in a recess provided in the long side clamp portions 231, 232. When the assembly 100A is clamped between the pair of long side clamp portions 231, 232, the compression spring S is interposed in a compressed state between the contact portion C and the long side wall 12b of the assembly 100A. As a result, a second load P2 is applied to the long side wall 12b via the contact portion C.

[0040] The second load P2 may be smaller than the pressure (first load P1) with which the pair of long side clamping parts 231, 232 clamp the assembly 100A, and is a design item that should be appropriately changed depending on, for example, the material and thickness of the long side wall 12b of the case body 12. The second load P2 may be a pressure that can adjust the gap G (see FIG. 5(A)) to 0.06 mm or less by deforming the long side wall 12b of the assembly 100A by 0.03 to 0.05 mm toward the sealing plate 14, for example. In one example, the second load P2 is preferably 1 / 100 to 1 / 40 of the first load P1. Although not particularly limited, when the case body 12 is made of aluminum with a thickness of 1 mm or less, the second load P2 is preferably about 1 N or more, for example, about 3 to 5 N. This allows the long side wall 12b to be appropriately attached to the long side of the sealing plate 14 in the assembly fixing step (S2) described later, thereby making the gap G smaller. The second load P2 can be adjusted by the spring constant (biasing force) of the compression spring S.

[0041] As shown in FIG. 3, the elastic parts 240 are disposed opposite to each other in the short side direction X. The elastic parts 240 are symmetrically disposed on the pair of long side clamp parts 231, 232. The elastic parts 240 are disposed opposite to the long side wall 12b of the assembly 100A. The elastic parts 240 are scattered along the long side wall 12b of the assembly 100A in a plan view. In other words, the elastic parts 240 are intermittently disposed on the surface of the assembly 100A facing the long side wall 12b. This increases the degree of freedom in designing the arrangement of the elastic parts 240 and the second load P2 (see FIG. 4), for example by increasing the number of the elastic parts 240 or increasing the second load P2 in a place where the gap G is likely to be large.

[0042] The elastic parts 240 are configured to directly face (contact) the long side wall 12b and locally (partially) press the long side wall 12b. The elastic parts 240 are arranged at equal intervals in the long side direction Y. In the long side direction Y, the long side clamp parts 231, 232 and the elastic parts 240 are alternately contacted with the long side wall 12b of the assembly 100A. Since a part of the long side wall 12b is in contact with not only the elastic parts 240 but also the metallic long side clamp parts 231, 232 (especially having high thermal conductivity), heat dissipation during laser welding is improved, and laser welding can be stably performed in the laser welding step (S3) described later. Note that, although seven elastic parts 240 are illustrated here, the number can be appropriately changed depending on, for example, the length of the long side wall 12b in the long side direction Y.

[0043] As shown in FIG. 4, in the height direction Z, the elastic portion 240 is preferably provided so as to press the upper end (the end on the sealing plate 14 side) of the long side wall 12b of the assembly 100A. In other words, it is preferably provided so as to press the side closer to the opening 12h than the upper end of the electrode body 20. The distance L3 from the upper end of the long side wall 12b to the elastic portion 240 (here, the distance to the axial center of the compression spring S) is preferably 10 mm or less, more preferably 6 mm or less. As described above, the long side wall 12b is more likely to bend and deform as it approaches the sealing plate 14 (the end on the opening 12h side). Therefore, by setting the distance L3 to a predetermined value or less, the second load P2 can be set small. The distance L3 is preferably 2 mm or more, more preferably 4 mm or more. As a result, even if the height of the long side wall 12b varies within the intersection range, the effect of the technology disclosed herein can be stably exhibited. Moreover, it is preferable that the elastic portion 240 is provided so as to press below (toward the bottom wall 12a) the lower end of the sealing plate 14. This makes it easier to deflect the long side wall 12b with the second load P2.

[0044] As shown in FIG. 3, the pair of short side clamping parts 233, 234 are configured to apply a predetermined load to the pair of short side walls 12c of the assembly 100A and the short side of the sealing plate 14, thereby clamping the short side walls 12c and the sealing plate 14. In detail, one short side clamping part 233 is provided on the surface of the second movable member 223 facing the assembly 100A. The other short side clamping part 234 is provided on the surface of the third movable member 224 facing the assembly 100A. The pair of short side clamping parts 233, 234 are provided so as to face the short side walls 12c of the assembly 100A. The pair of short side clamping parts 233, 234 are arranged opposite to each other in the long side direction Y. The pair of short side clamping parts 233, 234 are provided symmetrically in the long side direction Y across the assembly 100A. The material of the pair of short side clamping portions 233 and 234 may be the same as that of the pair of long side clamping portions 231 and 232 .

[0045] As shown in FIG. 3, the pair of short side clamping parts 233, 234 each extend along the short side direction X. The length of the pair of short side clamping parts 233, 234 in the short side direction X is approximately the same as the short side wall 12c of the assembly 100A. The pair of short side clamping parts 233, 234 are configured here to directly contact (abut) the short side wall 12c of the assembly 100A and press the assembly 100A. Although not shown in the figure, in the height direction Z, the pair of short side clamping parts 233, 234 are provided so as to face the upper end (the end on the sealing plate 14 side) of the short side wall 12c of the assembly 100A, similar to the long side clamping parts 231, 232.

[0046] In this embodiment, the pair of short side clamping portions 233, 234 are not provided with the elastic portion 240. This is because the length of the short side wall 12c facing the pair of short side clamping portions 233, 234 is shorter than the long side wall 12b, and a large gap is unlikely to occur between the short side wall 12c and the sealing plate 14. However, in other embodiments, the short side clamping portions 233, 234 may also be provided with one or more elastic portions 240, similar to the long side clamping portions 231, 232.

[0047] In the (S2) assembly fixing step, as shown in Figs. 3 and 4, the assembly 100A produced in the (S1A) assembly producing step is fixed by the fixing jig 200 prepared in the (S1B) jig preparing step to perform positioning for laser welding. Specifically, for example, the assembly 100A is inserted from above into an area defined by a pair of long side clamping parts 231, 232 and a pair of short side clamping parts 233, 234 of the fixing jig 200. Then, a first load P1 is applied to the long side wall 12b of the assembly 100A via the pair of long side clamping parts 231, 232. Also, a predetermined load is applied to the short side wall 12c of the assembly 100A via the pair of short side clamping parts 233, 234. As a result, the case body 12 and the sealing plate 14 are clamped and fixed by the fixing jig 200.

[0048] In this embodiment, the pair of long side clamping portions 231, 232 of the fixing jig 200 are provided with the elastic portion 240, so that the second load P2 is further applied to the long side wall 12b of the assembly 100A via the elastic portion 240. FIGS. 5(A) and 5(B) are plan views for explaining the function of the elastic portion 240. As shown in FIG. 5(A), in the assembly 100A produced in the (S1A) assembly production process, a large gap G may be formed between the long side wall 12b and the sealing plate 14 within the range of the specified processing accuracy due to processing errors (tolerance dimensions and straightness).

[0049] In such a case, as shown in FIG. 5(B), the compression spring S of the elastic part 240 arranged in the part with the gap G expands following the surface shape (waviness, etc.) of the long side wall 12b, and the elastic part 240 (specifically, the abutting part C) presses the long side wall 12b of the case body 12 toward the sealing plate 14 side (the front side in the short side direction X in FIG. 5(B)). As a result, the long side wall 12b is pressed against the long side of the sealing plate 14. This makes it possible to relatively reduce the gap G compared to a case where a conventional fixing jig not provided with the elastic part 240 is used (for example, a case where the entire long side clamp part is made of a hard material that does not have elasticity, such as metal). As a result, the long side wall 12b and the sealing plate 14 can be suitably attached to each other over the entire long side direction Y. Therefore, it is possible to suppress the occurrence of laser voids in the laser welding process (S3) described later.

[0050] The gap G does not necessarily have to be zero as long as it is small enough to prevent laser leakage in the laser welding process (S3) described below. Although this may vary depending on the laser light irradiation conditions, in one example, it is preferable that the gap G is reduced to 0.06 mm or less. For example, in a case where a gap G of up to about 0.094 mm may occur due to processing errors, it is sufficient for the gap G to be reduced to about 0.034 mm (= 0.094 mm - 0.06 mm) by the elastic portion 240.

[0051] In the (S3) laser welding step, with the case body 12 and sealing plate 14 of the assembly 100A fixed by the fixing jig 200, the outer peripheral edge of the sealing plate 14 is laser welded to the inner peripheral edge of the opening 12h of the case body 12 over the entire circumference. The conditions for irradiating the laser light (e.g., output, beam diameter, processing speed (scanning speed of the laser light), etc.) may be the same as in the past. In the technology disclosed herein, the gap G between the case body 12 and the sealing plate 14 is kept small. This makes it possible to suppress the occurrence of laser dropout. As a result, the electrode body 20 is less likely to be hit by the laser light, and damage to the electrode body 20 can be suppressed.

[0052] In addition, in this process, high-temperature molten metal may be generated as fine particles (so-called spatter) from the welding points, but since the gap G between the long side wall 12b of the case body 12 and the sealing plate 14 is kept small, even if spatter is generated, the molten metal can be prevented from falling into the case body 12. This prevents the molten metal from mixing into the electrode body 20 and causing a short circuit in the electrode body 20. Furthermore, since the case body 12 and the sealing plate 14 are in close contact with each other, thermal strain deformation of the sealing plate 14 in this process can be kept small.

[0053] In the liquid injection step (S4), a nonaqueous electrolyte is injected into the case body 12 from an injection hole (not shown) provided in the sealing plate 14. Then, the injection hole is sealed with a liquid injection plug or the like. In this manner, the electricity storage device 100 as shown in FIGS. 1 and 2 can be manufactured.

[0054] <Applications of electricity storage devices> The electricity storage device 100 can be used for various purposes, but is particularly preferably used as a large-scale (large-capacity) electricity storage device having a large battery case 10 and high energy density. Suitable applications include, for example, a power source for a motor (power source for driving a vehicle) mounted on a vehicle such as a plug-in hybrid electric vehicle (PHEV), a hybrid electric vehicle (HEV), or a battery electric vehicle (BEV).

[0055] Although the specific examples of the present invention have been described in detail above, the above-mentioned embodiments are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples exemplified above.

[0056] For example, in the above embodiment, the elastic part 240 is composed of the contact part C and the compression spring S, and the contact part C is a pressure pin. However, this is not limited to this. In a modified example, the contact part C may be, for example, a pressure ball having a substantially spherical outer shape. The elastic part 240 may be composed of a ball plunger equipped with a pressure ball and a compression spring S. According to such an embodiment, the processing of the long side clamp parts 231, 232 (attachment of the elastic part 240) becomes easy, and the manufacturing process can be simplified.

[0057] In another modification, the elastic portion 240 may be rubber or soft resin having rubber elasticity that elastically deforms in a direction toward the long side wall 12b and a direction away from the long side wall 12b. Examples of rubber include urethane rubber, ethylene propylene rubber, butyl rubber, and fluororubber. The soft resin is a synthetic resin that can be elastically deformed. Examples of soft resin include thermoplastic elastomers (elastic bodies). The rubber or soft resin having rubber elasticity may have a compressive deformation rate in the short side direction X ((thickness in the short side direction X before applying the first load P1-thickness in the short side direction X when the first load is applied) / thickness in the short side direction X before applying the first load P1) of 2% or more. This makes it possible to suppress the gap G to 0.06 mm or less. Note that, in the case of general urethane rubber (hardness around 60), the compressive deformation rate is about 10%, which is sufficient. According to this embodiment, the contact area between the elastic portion 240 and the long side wall 12b can be increased, and the effect of the technology disclosed herein can be exerted to a high level.

[0058] For example, in the above embodiment, the elastic portion 240 is provided in plurality and is scattered along the long side wall 12b of the case body 12. However, this is not limited to this. In another modified example, the elastic portion 240 may be in a band shape extending along the long side wall 12b of the case body 12 in a plan view. In this case, the number of elastic portions 240 may be one. The band-shaped elastic portion 240 is configured to continuously press the long side wall 12b along the long side direction Y.

[0059] FIG. 6 is a schematic longitudinal sectional view of the vicinity of the elastic part 241 according to the first modified example. As shown in FIG. 6, in the first modified example, there is one elastic part 241. The elastic part 241 is made of rubber or soft resin having rubber elasticity as described above. The length of the elastic part 241 in the height direction Z is approximately the same as that of the long side clamp part 232. Although not shown in the figure, the length of the elastic part 241 in the long side direction Y is also approximately the same as that of the long side clamp part 232. The elastic part 241 covers the end part of the long side clamp part 232 on the assembly body 100A side (the front side in FIG. 6). In this case, the long side clamp part 232 does not abut (directly contact) with the long side wall 12b of the assembly body 100A. The first load P1 is applied to the assembly body 100A via the elastic part 241. In this modification, the elastic portion 241 contacts the long side wall 12b continuously along the long side direction Y, preferably over the entire long side direction Y. This makes it easier for the elastic portion 241 to follow the surface shape of the long side wall 12b, and allows the long side wall 12b to be brought into closer contact with the sealing plate 14 at a higher level. Also, a load can be applied stably to the assembly 100A.

[0060] FIG. 7(A) is a schematic vertical cross-sectional view of the vicinity of the elastic part 242 according to the second modification. As shown in FIG. 7(A), in the second modification, the elastic part 242 includes a thin heat sink M1 and a compression spring S1. The heat sink M1 is disposed on the surface facing the assembly 100A. Like the elastic part 241 of the first modification, the heat sink M1 covers the end of the long side clamp part 232 on the assembly 100A side (the front side in FIG. 7(A)). The heat sink M1 is made of metal, and is made of a metal material having high heat dissipation and flexibility, such as copper. The heat sink M1 is flexible (flexible in the short side direction X). The thickness t1 of the heat sink M1 is typically thinner than the plate thickness of the case body 12, and is preferably about 0.1 to 0.3 mm, for example. Although not shown in the drawings, a plurality of compression springs S1 are arranged (scattered) along the long side direction Y as in the embodiment. The compression springs S1 may be similar to the compression springs S in the embodiment. When it is desired to keep the gap g1 (see FIG. 7(B)) to 0.06 mm or less, the difference between the maximum tensile length and the maximum compressed length of the compression spring S1 may be 0.03 to 0.05 mm.

[0061] FIG. 7(B) is a view corresponding to FIG. 5(B) according to the second modified example. As shown in FIG. 7(B), in this modified example, the compression spring S1 of the elastic part 242 arranged in the part with the gap (the center part in FIG. 7(B)) is stretched compared to the compression spring S1 of the elastic part 242 arranged in the part without the gap (both ends in FIG. 7(B)). As a result, in the part with the gap, the heat sink M1 is pressed against the long side wall 12b, and the long side wall 12b is pressed against the sealing plate 14 side. According to this embodiment, the heat sink M1 and the long side wall 12b are in contact with each other over a larger area. In addition, the heat sink M1 is also in contact with the long side clamp part 232 made of metal on the opposite side, so that the heat generated during laser welding can be suitably released to the long side clamp part 232. Therefore, the heat dissipation can be particularly suitably improved. Therefore, the laser welding can be performed particularly stably.

[0062] FIG. 8(A) is a schematic vertical cross-sectional view of the vicinity of the elastic part 243 according to the third modified example. As shown in FIG. 8(A), in the third modified example, the elastic part 243 includes a thin heat sink M2 and an elastic body E. The heat sink M2 may be the same as the heat sink M1 of the second modified example. The heat sink M2 is connected to the metal long side clamp part 232, and a heat dissipation path is secured. The elastic body E is made of the above-mentioned rubber or soft resin having rubber elasticity. When it is desired to suppress the gap g2 (see FIG. 8(B)) to 0.06 mm or less, it is preferable that the above-mentioned compressive deformation rate of the elastic body E is 2% or more.

[0063] Fig. 8(B) is a view corresponding to Fig. 5(B) according to the third modified example. As shown in Fig. 8(B), in this modified example, the elastic body E having a thickness of 3 mm is deformed to 2 mm by the first load P1, that is, compressed by 1 mm (an amount sufficiently larger than 0.06 mm). As a result, the heat sink M2 is continuously pressed against the long side wall 12b, and the long side wall 12b is pressed toward the sealing plate 14. According to this embodiment, the elastic portion 243 has heat dissipation properties, and the heat sink M2 and the long side wall 12b come into contact with each other over a wide area, so that the effect of the technology disclosed herein can be exerted at a high level.

[0064] In addition, in the technology disclosed herein, the above-mentioned embodiment and modified examples can be appropriately combined. For example, in the long side clamping parts 231, 232, dot-like elastic parts 240 may be arranged at both ends in the long side direction Y as in the embodiment, and a strip-like elastic part 241 may be arranged at the center of the long side direction Y as in the first modified example. According to this aspect, the positioning accuracy of the assembly 100A can be improved. Conversely, in the long side clamping parts 231, 232, dot-like elastic parts 240 may be arranged at the center of the long side direction Y as in the embodiment, and a strip-like elastic part 241 may be arranged at both ends in the long side direction Y as in the first modified example. According to the study by the present inventor, a large gap is likely to occur at the end of the long side direction Y. According to this aspect, the gap can be reduced at the end of the long side direction Y, and the heat dissipation during laser welding can be suitably improved at the center of the long side direction Y.

[0065] As described above, specific aspects of the technology disclosed herein include those described in the following sections. Item 1: A method for manufacturing an electricity storage device including a case body having a rectangular bottom wall, a pair of long side walls extending from a long side of the bottom wall and facing each other, a pair of short side walls extending from a short side of the bottom wall and facing each other, and an opening facing the bottom wall, a rectangular sealing plate disposed in the opening of the case body and having an outer peripheral edge portion laser-welded to an inner peripheral edge portion of the opening of the case body, and an electrode body housed in the case body, the method including an assembly fabrication step of housing the electrode body inside the case body and disposing the sealing plate in the opening of the case body to fabricate an assembly, and a sealing plate for sealing the long side walls of the case body. a pair of long side clamping parts that apply a first load to the case body and the sealing plate from a side opposite to the assembly to clamp the case body and the sealing plate, and one or more elastic parts that are provided on respective surfaces of the pair of long side clamping parts facing the assembly and apply a second load to the assembly that is smaller than the first load; an assembly fixing step of fixing the assembly with the fixing jig; and a laser welding step of laser welding the sealing plate and the case body together while the assembly is fixed with the fixing jig. Item 2: The method for producing an electricity storage device according to item 1, wherein the elastic portion is plural, and the plural elastic portions are scattered along the long side wall in a plan view. Item 3: The method for manufacturing an electricity storage device according to item 1 or 2, wherein, when a direction from the bottom wall toward the opening is defined as a height direction, the multiple elastic portions are each arranged so as to press, in the height direction, a side of the long side wall that is closer to the bottom wall than a lower end of the sealing plate and a side that is closer to the opening than an upper end of the electrode body. Item 4: A method for manufacturing an electricity storage device according to any one of items 1 to 3, wherein at least one of the plurality of elastic members has an abutment portion that abuts against the long side wall, and a compression spring that is attached to the abutment portion and expands and contracts in a direction toward the assembly and a direction away from the assembly. Item 5: A method for manufacturing an electricity storage device described in any one of items 1 to 4, wherein at least one of the multiple elastic parts has rubber or a soft resin having rubber elasticity that elastically deforms in a direction toward the assembly and a direction away from the assembly. Item 6: The method for producing an electricity storage device according to item 1, wherein the elastic portion has a band-shaped portion extending along the long side wall in a plan view. Item 7: The method for producing an electricity storage device according to item 6, wherein the elastic portion has rubber or a soft resin having rubber elasticity that elastically deforms in a direction toward the assembly and a direction away from the assembly. Item 8: The method for producing an electricity storage device according to item 6 or 7, wherein the elastic portion has a metal heat sink on a surface facing the assembly. Item 9: A fixing jig used when laser welding an outer peripheral edge of a sealing plate to an inner peripheral edge of the opening of the case body for an assembly including a case body having a rectangular bottom wall, a pair of long side walls extending from a long side of the bottom wall and facing each other, a pair of short side walls extending from a short side of the bottom wall and facing each other, and an opening facing the bottom wall, a rectangular sealing plate disposed in the opening of the case body, and an electrode body contained in the case body, the fixing jig comprising a pair of long side clamping portions that apply a first load to the case body and the sealing plate from the long side wall side of the case body to clamp the case body and the sealing plate, and one or more elastic portions that are provided on respective surfaces of the pair of long side clamping portions facing the assembly and that apply a second load to the assembly that is smaller than the first load. [Explanation of symbols]

[0066] 10 Battery case 12 Case body 12b Long side wall 12c short side wall 12h opening 14 Sealing plate 20 Electrode body 100 Energy storage device 100A Assembly 200 Fixing jig 210 Cabinet 221 Fixing member 222 First movable member 231 Long side clamp part 232 Long side clamp part 240, 241, 242, 243 Elastic part

Claims

1. a case body having a rectangular bottom wall, a pair of long side walls extending from a long side of the bottom wall and facing each other, a pair of short side walls extending from a short side of the bottom wall and facing each other, and an opening facing the bottom wall; a rectangular sealing plate disposed within the opening of the case body, the outer peripheral edge of which is laser welded to the inner peripheral edge of the opening of the case body; An electrode body accommodated in the case body; A method for manufacturing an electricity storage device comprising: an assembly fabrication process of housing the electrode body inside the case body and disposing the sealing plate in the opening of the case body to fabricate an assembly; a jig preparation process for preparing a fixing jig including a pair of long side clamping parts that clamp the case body and the sealing plate by applying a first load to the case body and the sealing plate from the long side wall side of the case body, and one or more elastic parts that are provided on respective surfaces of the pair of long side clamping parts facing the assembly and that apply a second load to the assembly that is smaller than the first load; an assembly fixing step of fixing the assembly by the fixing jig; a laser welding process of laser welding the sealing plate and the case body together in a state where the assembly is fixed by the fixing jig; A method for manufacturing an electricity storage device, comprising:

2. The elastic portion is a plurality of elastic portions, The elastic portions are scattered along the long side wall in a plan view. A method for producing the electricity storage device according to claim 1 .

3. When the direction from the bottom wall toward the opening is defined as a height direction, the elastic portions are each disposed in the height direction so as to press a side of the long side wall that is closer to the bottom wall than a lower end of the sealing plate and that is closer to the opening than an upper end of the electrode body. The method for producing the electricity storage device according to claim 2 .

4. At least one of the plurality of elastic portions includes an abutment portion that abuts against the long side wall, and a compression spring that is attached to the abutment portion and expands and contracts in a direction toward the long side wall and a direction away from the long side wall. A method for manufacturing the electricity storage device according to claim 1 .

5. At least one of the plurality of elastic portions has rubber or a soft resin having rubber elasticity that elastically deforms in a direction toward the long side wall and in a direction away from the long side wall. A method for manufacturing the electricity storage device according to claim 1 .

6. The elastic portion has a band-shaped portion extending along the long side wall in a plan view. A method for producing the electricity storage device according to claim 1 .

7. The elastic portion has rubber or a soft resin having rubber elasticity that elastically deforms in a direction toward the long side wall and in a direction away from the long side wall. The method for producing the electricity storage device according to claim 6 .

8. the elastic portion has a metal heat sink on a surface facing the assembly; A method for producing the electricity storage device according to claim 6 or 7.

9. a case body having a rectangular bottom wall, a pair of long side walls extending from a long side of the bottom wall and facing each other, a pair of short side walls extending from a short side of the bottom wall and facing each other, and an opening facing the bottom wall; a rectangular sealing plate disposed in the opening of the case body; and an electrode body housed in the case body, the fixing jig being used when laser welding an outer peripheral edge of the sealing plate to an inner peripheral edge of the opening of the case body, a pair of long side clamps that apply a first load to the case body and the sealing plate from the long side wall side of the case body to clamp the case body and the sealing plate; one or more elastic portions provided on respective surfaces of the pair of long side clamp portions facing the assembly, the elastic portions applying a second load to the assembly that is smaller than the first load; A fixing jig comprising:

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