Battery manufacturing method and battery

Abstract

A manufacturing method for a battery according to an embodiment involves: spacing, in a lid member, the outer circumference of which is formed by a first edge and a second edge that extend in a first direction and a third edge and a fourth edge that extend in a second direction that crosses the first direction, a second terminal away from a first terminal toward the side where the fourth edge is located; and attaching the pair of terminals to the lid member. In the manufacturing method, a proximal portion that is closer to the first terminal than the third edge is formed on the first edge, and the outer circumference of the lid member is welded to an exterior container by a plurality of instances of laser welding. At least the proximal portion is welded in the initial laser welding, and at least one starting point and at least one ending point of the multiple laser welds are located in a range between the pair of terminals.

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION Embodiments of the present invention relate to a method for manufacturing a battery and a battery. [Background technology]

[0002] Some batteries, such as lithium-ion secondary batteries, have an exterior portion formed from an outer container and a lid member. In such batteries, an electrode group is housed in an internal cavity of the outer container, and the internal cavity is open to the outside of the outer container. The lid member is attached to the outer container in a state where it closes the opening of the internal cavity. A pair of terminals is attached to the lid member in a state where they are exposed to the outside, and each of the pair of terminals is electrically connected to the electrode group. In addition, in battery manufacturing, the lid member is attached to the outer container by welding the entire outer periphery of the lid member to the outer container by laser welding or the like. Therefore, a welded portion where the lid member is welded to the outer container is formed in the battery. In addition, an insulator and a gasket are provided at each attachment portion of the terminal to the lid member. In addition, at each attachment portion of the terminal to the lid member, the insulator and the gasket electrically insulate the terminal from the lid member, and the gasket prevents gas from leaking to the outside through the attachment portion of the terminal.

[0003] As described above, in batteries in which the exterior part is formed from an outer container and a lid member, a large current is achieved by, for example, increasing the volume of each terminal. Here, as the volume of each terminal increases, the distance between the terminal, the gasket, and the insulator and the welded portion of the lid member to the outer container decreases. Furthermore, when the lid member is welded to the outer container by laser welding, heat is generated by the welding, causing the temperature at the welded portion and its vicinity to rise. In batteries in which the exterior part is formed from an outer container and a lid member, even when the volume of each of the pair of terminals is increased, it is necessary to reduce the impact of heat generated by welding the lid member to the outer container on the gasket, insulator, etc. That is, even when manufacturing a battery in which the gasket and insulator are close to the welded portion of the lid member to the outer container, it is necessary to reduce the temperature rise of the gasket, etc. caused by heat generated by welding when the lid member is welded to the outer container. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 8-250079 [Patent Document 2] Japanese Patent Application Publication No. 2018-116881 Summary of the Invention [Problem to be solved by the invention]

[0005] The problem that the present invention aims to solve is to provide a battery and a method for manufacturing such a battery in which the impact of heat generated when welding a lid member to an outer container on a gasket, etc. is reduced by realizing a large current by increasing the volume of the terminals. [Means for solving the problem]

[0006] In a manufacturing method of a battery according to an embodiment, an outer container is formed in which an internal cavity is open to the outside, and a lid member is formed in which a first edge and a second edge along a first direction and a third edge and a fourth edge along a second direction intersecting the first direction form an outer periphery. In the manufacturing method, the second terminal is separated from the first terminal toward the side where the fourth edge is located in the first direction, and the first terminal and the second terminal are attached to the lid member, and a first adjacent portion closer to the first terminal than the third edge is attached to the first edge. , a second adjacent portion closer to the first terminal than the third edge, and a second adjacent portion closer to the second edge, respectively. In the manufacturing method, an electrode group electrically connected to the first terminal and the second terminal is housed in an internal cavity of the outer container, and the opening of the internal cavity is closed with a lid member. In the manufacturing method, the lid member that has closed the opening of the internal cavity is laser-welded multiple times to weld the entire outer periphery of the lid member to the outer container. In the first laser welding, at least a first adjacent portion of a first edge is welded, a second laser welding at least a second adjacent portion of the second edge; One or more start points and one or more end points of the multiple laser weldings are located in an intermediate range between the first terminal and the second terminal in the first direction. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view showing a battery according to a first embodiment. [Figure 2] FIG. 2 is a schematic diagram showing the battery according to the first embodiment as viewed from one side in the depth direction, with a cross section of a portion perpendicular or substantially perpendicular to the depth direction. [Figure 3] FIG. 3 is a perspective view showing the lid member and its vicinity of the battery according to the first embodiment, with a pair of terminals omitted. [Figure 4] FIG. 4 is a plan view showing the battery according to the first embodiment as viewed from the side where the lid member is located in the height direction. [Figure 5] FIG. 5 is a schematic view showing an example of welding a lid member to an outer container, which is performed during the manufacture of the battery according to the first embodiment. [Figure 6] FIG. 6 is a cross-sectional view that schematically shows an example of a portion where one weld mark overlaps another weld mark at a welded portion of the lid member to the outer casing of the battery according to the first embodiment. [Figure 7] FIG. 7 is a schematic diagram showing an example of a welding mark formed by laser welding. [Figure 8] FIG. 8 is a schematic view showing an example of welding a lid member to an outer container performed during the manufacture of a battery according to a modified example of the first embodiment. [Figure 9] FIG. 9 is a schematic view showing an example of welding a lid member to an outer container performed during the manufacture of a battery according to the second embodiment. [Figure 10] FIG. 10 is a schematic view showing an example of welding a lid member to an outer container in a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments will be described with reference to the drawings.

[0009] FIGS. 1 and 2 show a battery 1 according to a first embodiment. As shown in FIGS. 1 and 2, the battery 1 includes an electrode group 2, an outer casing 3, and a lid member 5. The outer casing 3 and the lid member 5 form an exterior of the battery 1. The outer casing 3 and the lid member 5 are each made of a metal such as aluminum, an aluminum alloy, iron, copper, or stainless steel, and are electrically conductive. The exemplary battery 1 (outer casing 3) shown in FIGS. 1 and 2 has a lateral direction (indicated by arrow X1), a depth direction (indicated by arrow Y1) that intersects (orthogonal or substantially perpendicular to) the lateral direction, and a height direction (indicated by arrow Z1) that intersects (orthogonal or substantially perpendicular to) both the lateral and depth directions. The dimensions of the battery 1 and the outer casing 3 along the depth direction are smaller than the dimensions along the lateral direction and the height direction, respectively. Note that FIG. 1 is a perspective view, and FIG. 2 shows a view from one side in the depth direction, partially illustrating a cross section perpendicular or substantially perpendicular to the depth direction.

[0010] The outer container 3 includes a bottom wall 6 and a peripheral wall 7. An internal cavity 8 is formed inside the outer container 3, and the internal cavity 8 opens toward the side opposite the bottom wall 6 in the height direction of the battery 1. The peripheral wall 7 covers the entire periphery of the internal cavity 8 from the outer periphery. The peripheral wall 7 is connected to the bottom wall 6 and extends from the bottom wall 6 along the height direction of the battery 1. The edge of the opening of the internal cavity 8 is formed by the end of the peripheral wall 7 opposite the bottom wall 6. The peripheral wall 7 includes side walls 11A, 11B, 12A, and 12B. The side walls 11A and 11B face each other in the depth direction, sandwiching the internal cavity 8 therebetween. The side walls 12A and 12B face each other in the lateral direction, sandwiching the internal cavity 8 therebetween. Each of the side walls 11A and 11B extends in the lateral direction between the side walls 12A and 12B. Each of the side walls 12A and 12B extends in the depth direction between the side walls 11A and 11B.

[0011] 1 and 2, the dimensions of each of the side walls 11A, 11B in the lateral direction are larger than the dimensions of each of the side walls 12A, 12B in the depth direction. Therefore, the dimensions of the internal cavity 8 and the opening of the internal cavity 8 in the lateral direction are larger than the dimensions in the depth direction. The cover member 5 is attached to the peripheral wall 7 at the end opposite the bottom wall 6. Therefore, the cover member 5 closes the opening of the internal cavity 8. The cover member 5 and the bottom wall 6 face each other in the height direction, sandwiching the internal cavity 8 therebetween.

[0012] The electrode group 2 is housed in the internal cavity 8. The electrode group 2 includes a positive electrode and a negative electrode (neither of which is shown). In the electrode group 2, a separator (not shown) is interposed between the positive electrode and the negative electrode. The separator has electrical insulation properties and electrically insulates the positive electrode from the negative electrode. In one example, the electrode group 2 has a wound structure. In this case, in the electrode group 2, the positive electrode, the negative electrode, and the separator are wound with the separator sandwiched between the negative electrodes. In another example, the electrode group 2 has a stack structure. In this case, in the electrode group 2, a plurality of positive electrodes and a plurality of negative electrodes are alternately stacked, and a separator is provided between the positive electrode and the negative electrode.

[0013] In addition, in the internal cavity 8, the electrode group 2 is held (impregnated) with an electrolytic solution (not shown). The electrolytic solution may be a non-aqueous electrolytic solution in which an electrolyte is dissolved in an organic solvent, or may be an aqueous electrolytic solution such as an aqueous solution. Instead of the electrolytic solution, a gel electrolyte or a solid electrolyte may be used. When a solid electrolyte is used as the electrolyte, the solid electrolyte is interposed between the positive electrode and the negative electrode in place of a separator in the electrode group 2. In this case, the positive electrode is electrically insulated from the negative electrode by the solid electrolyte.

[0014] In the battery 1, a pair of terminals (electrode terminals) 13A, 13B of opposite polarity are attached to the cover member 5. Each of the terminals 13A, 13B is made of a conductive material such as metal. One of the pair of terminals 13A, 13B serves as the positive terminal of the battery 1, and the other of the pair of terminals 13A, 13B serves as the negative terminal of the battery 1. Each of the terminals 13A, 13B is attached to the cover member 5 with a portion exposed to the outside. In the example shown in FIGS. 1 and 2, the terminals 13A, 13B are spaced apart from each other in the lateral direction of the battery 1.

[0015] FIG. 3 shows the lid member 5 and its vicinity, omitting the pair of terminals 13A and 13B. As shown in FIG. 3 and other figures, a pair of through holes 15 is formed in the lid member 5, and each of the through holes 15 penetrates the lid member 5 from the outer surface to the inner surface. The pair of through holes 15 is formed spaced apart from each other in the lateral direction of the battery 1. Each of the terminals 13A and 13B is inserted into the internal cavity 8 through a corresponding one of the pair of through holes 15. In the internal cavity 8, each of the terminals 13A and 13B is electrically connected to the electrode group 2 via one or more leads (not shown). In the battery 1, one of the terminals 13A and 13B, which is a positive terminal, is electrically connected to the positive electrode of the electrode group 2 via one or more leads. The other of the terminals 13A and 13B, which is a negative terminal, is electrically connected to the negative electrode of the electrode group 2 via one or more leads. In addition, in the internal cavity 8, the leads electrically connecting the terminals 13A and 13B to the electrode group 2 are electrically insulated from the outer container 3 and the lid member 5 by an insulating member (not shown).

[0016] As shown in Figures 1 to 3, a pair of insulators 16 are disposed on the outer surface of the cover member 5. Each of the insulators 16 is electrically insulating and is sandwiched between a corresponding one of the terminals 13A, 13B and the outer surface of the cover member 5. As shown in Figure 3, the battery 1 also includes a pair of gaskets 17, one of which is disposed in each of the pair of through holes 15. Each of the gaskets 17 is electrically insulating. In each of the through holes 15, the gasket 17 is sandwiched between a corresponding one of the terminals 13A, 13B and the periphery of the through hole 15. The outer periphery of each of the gaskets 17 is covered by a corresponding one of the insulators 16. The corresponding one of the insulators 16 and the corresponding one of the gaskets 17 prevents each of the terminals 13A, 13B from contacting the cover member 5, and the terminals 13A, 13B are electrically insulated from the cover member 5. Furthermore, in each of the through holes 15, the gap between the corresponding one of the terminals 13A, 13B and the periphery is kept airtight and liquidtight by the gasket 17. Therefore, each of the gaskets 17 seals the corresponding one of the through holes 15, and prevents leakage of gas, electrolyte, and the like to the outside through the attachment portion of the corresponding one of the terminals 13A, 13B.

[0017] In the battery 1, a gas release valve and a liquid filling port may be formed in the cover member 5. In this case, a sealing plate that closes the liquid filling port is welded to the outer surface of the cover member 5. The gas release valve and the liquid filling port are disposed between the pair of terminals 13A, 13B in the lateral direction of the battery 1. In addition, the battery 1 does not necessarily have to be provided with a gas release valve, a liquid filling port, etc., as in the examples shown in FIGS. 1 to 3, etc.

[0018] FIG. 4 shows the battery 1 as viewed from the side where the lid member 5 is located in the height direction. As shown in FIGS. 1 to 4, the lid member 5 is formed in a plate shape or a substantially plate shape. The lid member 5 has a first direction (the direction indicated by arrow X2), a second direction (the direction indicated by arrow Y2) that intersects (is perpendicular or substantially perpendicular to) the first direction, and a thickness direction (a direction perpendicular or substantially perpendicular to the plane of the paper in FIG. 4) that intersects (is perpendicular or substantially perpendicular to) both the first and second directions. The dimension of the lid member 5 along the first direction is larger than the dimension along the second direction. Therefore, in the example shown in FIG. 4, the first direction is also referred to as the longitudinal direction, and the second direction is also referred to as the lateral direction. Furthermore, the dimension of the lid member 5 along the second direction is larger than the dimension along the thickness direction.

[0019] The lid member 5 has a pair of edges 21A, 21B extending along a first direction and a pair of edges 22A, 22B extending along a second direction. The edges 21A, 21B are spaced apart from each other in the second direction, and each of the edges 21A, 21B extends along the first direction (longitudinal direction) between the edges 22A, 22B. The edges 22A, 22B are spaced apart from each other in the first direction, and each of the edges 22A, 22B extends along the second direction (transverse direction) between the edges 21A, 21B. The edges 21A, 21B, 22A, and 22B form an outer periphery (outer periphery) of the lid member 5, and the lid member 5 is surrounded by the edges 21A, 21B, 22A, and 22B. The dimensions of edge (first edge) 21A and edge (second edge) 21B along the first direction are greater than the dimensions of edge (third edge) 22A and edge (fourth edge) 22B along the second direction, respectively. For this reason, edges 21A and 21B are also referred to as long edges, and edges 22A and 22B are also referred to as short edges.

[0020] The cover member 5 is formed in a rectangular or substantially rectangular shape when viewed in the plate thickness direction. The cover member 5 has four corners 25 to 28. Corner (first corner) 25 is formed between edge 21A and edge 22A, corner (second corner) 26 is formed between edge 21B and edge 22A, corner (third corner) 27 is formed between edge 21A and edge 22B, and corner (fourth corner) 28 is formed between edge 21B and edge 22B. In addition, in the cover member 5, a pair of terminals 13A, 13B are arranged spaced apart from each other in the first direction (longitudinal direction). In this embodiment, terminal (first terminal) 13A is positioned closer to edge (third edge) 22A than terminal (second terminal) 13B, and terminal 13B is attached to cover member 5 away from terminal 13A in the first direction toward the side where edge (fourth edge) 22B is located.

[0021] Edge (first edge) 21A has a proximal portion (first proximal portion) P1 that is located closer to terminal 13A than edge (third edge) 22A, and edge (second edge) 21B has a proximal portion (second proximal portion) P2 that is located closer to terminal 13A than edge 22A. The distances of proximal portions P1 and P2 from terminal 13A are smaller than the distance of edge 22A from terminal 13A. The distances of proximal portions P1 and P2 from gasket 17, insulator 16, etc., which are disposed in the mounting portion of terminal 13A, are also smaller than the distance of edge 22A from gasket 17, insulator 16, etc., which are disposed in the mounting portion of terminal 13A. Here, a distance La1 of a proximal portion P1 of edge (first edge) 21A, a distance La2 of a proximal portion P2 of edge (second edge) 21B, and a distance Lb1 of edge (third edge) 22A are defined for gasket 17 at the mounting portion of terminal (first terminal) 13A. Each of distances La1 and La2 is smaller than distance Lb1.

[0022] Edge (first edge) 21A has a proximal portion (third proximal portion) P3 that is located closer to terminal 13B than edge (fourth edge) 22B, and edge (second edge) 21B has a proximal portion (fourth proximal portion) P4 that is located closer to terminal 13B than edge 22B. The distances of proximal portions P3 and P4 from terminal 13B are smaller than the distance of edge 22B from terminal 13B. The distances of proximal portions P3 and P4 from gasket 17, insulator 16, etc., that are disposed in the mounting portion of terminal 13B are also smaller than the distance of edge 22B from gasket 17, insulator 16, etc., that are disposed in the mounting portion of terminal 13B. Here, a distance La3 of the adjacent portion P3 of edge (first edge) 21A, a distance La4 of the adjacent portion P4 of edge (second edge) 21B, and a distance Lb2 of edge (fourth edge) 22B are defined for gasket 17 of the mounting portion of terminal (second terminal) 13B. Each of distances La3 and La4 is smaller than distance Lb2.

[0023] The lid member 5 is attached to the outer container 3 with its plate thickness direction coinciding or approximately coinciding with the height direction of the battery 1 (outer container 3). Furthermore, in the lid member 5 attached to the outer container 3, the first direction (longitudinal direction) coincides or approximately coincides with the lateral direction of the battery 1, and the second direction (transverse direction) coincides or approximately coincides with the depth direction of the battery 1. Therefore, when the lid member 5 is attached to the outer container 3, the edges 21A and 21B each extend along the lateral direction of the battery 1, and the edges 22A and 22B each extend along the depth direction of the battery 1.

[0024] The lid member 5 has an outer periphery formed by edges 21A, 21B, 22A, and 22B, which is welded to the outer container 3 along the entire periphery. Therefore, a welded portion between the lid member 5 and the outer container 3 is formed along the entire circumferential direction of the lid member 5. The lid member 5 is attached to the outer container 3 by welding the outer periphery of the lid member 5 to the outer container 3 along the entire periphery. In this embodiment, in manufacturing the battery 1, the lid member 5 is welded to the outer container 3 by laser welding the lid member 5 multiple times with the opening of the internal cavity 8 closed by the lid member 5, thereby forming a welded portion of the lid member 5 to the outer container 3. The lid member 5 is welded to the side wall 11A of the outer container 3, the edge 21B is welded to the side wall 11B of the outer container 3, the edge 22A is welded to the side wall 12A of the outer container 3, and the edge 22B is welded to the side wall 12B of the outer container 3.

[0025] In manufacturing the battery 1, first, the outer container 3 and the lid member 5 are formed. At this time, an internal cavity 8 is formed in the outer container 3, and edges 21A, 21B, 22A, and 22B and corners 25-28 are formed in the lid member 5. Then, the terminals 13A and 13B are attached to the lid member 5. At this time, the terminal 13B is attached to the lid member 5 away from the terminal 13A toward the side where the edge (fourth edge) 22B is located in the first direction. Furthermore, an insulator 16 and a gasket 17 are attached to the lid member 5 at the attachment portions of the terminals 13A and 13B to the lid member 5. Then, each of the terminals 13A and 13B attached to the lid member 5 is electrically connected to the electrode group 2 via one or more leads or the like. At this time, one of the terminals 13A and 13B is electrically connected to the positive electrode of the electrode group 2, and the other of the terminals 13A and 13B is electrically connected to the negative electrode of the electrode group 2.

[0026] Then, with terminals 13A and 13B electrically connected to electrode group 2, electrode group 2 is inserted into internal cavity 8 of outer container 3, and the opening of internal cavity 8 is closed with lid member 5. Then, with the opening of internal cavity 8 closed with lid member 5, laser welding is performed multiple times on lid member 5 to weld lid member 5 to outer container 3, thereby forming a welded portion of lid member 5 to outer container 3. Here, in manufacturing battery 1, one weld mark is formed each time laser welding is performed to attach lid member 5 to outer container 3. In this embodiment, laser welding is performed multiple times, and therefore multiple weld marks are formed in the welded portion of lid member 5 to outer container 3 in battery 1. In battery 1, the same number of weld marks are formed in the welded portion of lid member 5 to outer container 3 as the number of times laser welding was performed to attach lid member 5 to outer container 3.

[0027] FIG. 5 shows an example of welding the lid member 5 to the outer container 3 during the manufacture of the battery 1. In FIG. 5, the battery 1 is shown as viewed from the side where the lid member 5 is located in the height direction. In the example shown in FIG. 5, five laser welding processes are performed to weld the lid member 5 to the outer container 3. In the first laser welding, welding is performed between a midpoint (first midpoint) α1 of the edge (first edge) 21A and the corner (first corner) 25, passing through a proximal portion (first proximal portion) P1. In the example shown in FIG. 5, welding is performed from the midpoint α1 to the corner 25, passing through the proximal portion P1 (arrow A1). That is, welding is performed starting from the midpoint α1 and ending at the corner 25, passing through the proximal portion P1. As a result, the portion between the midpoint α1 and the corner 25, including the proximal portion P1, is welded to the outer container 3.

[0028] Note that the first laser welding may be performed from corner 25 to midpoint α1 through adjacent portion P1, i.e., in the opposite direction from arrow A1. In this case, welding is performed starting from corner 25 and ending at midpoint α1 through adjacent portion P1. Even when the first laser welding is performed in the opposite direction from arrow A1, welding is performed between midpoint (first midpoint) α1 and corner (first corner) 25 through adjacent portion (first adjacent portion) P1.

[0029] In the second laser welding, welding is performed from corner (second corner) 26 to corner (fourth corner) 28, passing through edge (second edge) 21B (arrow A2). That is, welding is performed starting from corner 26 and ending at corner 28, passing through adjacent portions P2 and P4 in that order. As a result, the portion between corner 26 and corner 28, including adjacent portions P2 and P4, is welded to the outer container 3, and the entire edge 21B is welded to the outer container 3. Note that the second laser welding is performed only from corner 26 to corner 28, and not from corner 28 to corner 26. That is, the second laser welding is not performed in the opposite direction to arrow A2.

[0030] In the third laser welding, welding is performed from the corner (third corner) 27 to the midpoint (second midpoint) α2 of the edge (first edge) 21A, passing through the adjacent portion P3 and the midpoint α1 (arrow A3). That is, welding is performed starting from the corner 27 and ending at the midpoint α2, passing through the adjacent portion P3 and the midpoint α1 in that order. As a result, the portion between the corner 27 and the midpoint α2, including the adjacent portion P3, is welded to the outer container 3. Note that the third laser welding is performed only from the corner 27 toward the midpoint α2, and is not performed from the midpoint α2 toward the corner 27. That is, the third laser welding is not performed in the opposite direction to the arrow A3.

[0031] Furthermore, the midpoint α2 is located on the side of the corner 25 relative to the midpoint α1. Therefore, the third laser welding is performed beyond the midpoint α1, passing through the portion where the first laser welding was performed. Therefore, the third laser welding is performed overlapping the welding portion where the first laser welding was performed between the midpoints α1 and α2 on the edge (first edge) 21A. Furthermore, an intermediate range M is defined between the terminals 13A and 13B in the first direction (longitudinal direction). In the example of FIG. 5, the midpoints α1 and α2 are located in the intermediate range. Therefore, the portion where the third laser welding is performed overlapping the first laser welding, i.e., the portion of the edge 21A between the midpoints α1 and α2, is located in the intermediate range M.

[0032] In the fourth laser welding, welding is performed between corner (first corner) 25 and corner (second corner) 26, passing through edge (third edge) 22A. In the fourth laser welding, either corner 25 or 26 may be the starting point. In one example of FIG. 5 , in the fourth laser welding, welding is performed starting from corner 25, passing through edge 22A, and ending at corner 26 (arrow A4). However, in another example, in the fourth laser welding, welding may be performed starting from corner 26, passing through edge 22A, and ending at corner 25. In the fourth laser welding, the portion between corners 25 and 26 is welded to the outer container 3, and the entire edge 22A is welded to the outer container 3. Here, at corner 25, a fourth laser welding is performed overlapping the welded portion that was welded the first time. Then, at corner 26, a fourth laser welding is performed overlapping the welded portion that was welded the second time.

[0033] In the fifth and final laser welding, the corner (third corner) 27 and the corner (fourth corner) 28 are welded through the edge (fourth edge) 22B. The fifth laser welding may start from either corner 27 or 28. In one example shown in FIG. 5 , the fifth laser welding starts from corner 28, passes through edge 22B, and ends at corner 27 (arrow A5). However, in another example, the fifth laser welding may start from corner 27, passes through edge 22B, and ends at corner 28. In the fifth laser welding, the portion between corners 27 and 28 is welded to the outer container 3, and the entire edge 22B is welded to the outer container 3. Here, at corner 27, a fifth laser welding is performed overlapping the welded portion that was welded the first time. At corner 28, a fifth laser welding is performed overlapping the welded portion that was welded the second time.

[0034] Because the lid member 5 is welded to the outer container 3 as described above, in this embodiment, five weld marks are formed in the welded portion of the lid member 5 to the outer container 3. The first weld mark corresponding to the first laser welding extends between the intermediate position α1 of the edge 21A and the corner 25 through the adjacent portion P1. The second weld mark corresponding to the second laser welding extends between the corner 26 and the corner 28 through the edge 21B including the adjacent portion P2. The third weld mark corresponding to the third laser welding extends between the corner 27 and the intermediate position α2 through the adjacent portion P3 and the intermediate position α1, which is located on the side of the edge 21A where the corner 25 is located relative to the intermediate position α1. The fourth weld mark corresponding to the fourth laser welding extends between the corners 25 and 26 through the edge 22A. The fifth weld mark corresponding to the fifth laser welding extends between the corners 27 and 28 through the edge 22B.

[0035] In the battery 1 of this embodiment, the third weld mark overlaps the first weld mark between midpoints α1 and α2 on the edge 21A at the welded portion of the lid member 5 to the outer container 3. In the example shown in FIG. 5 , the midpoints α1 and α2 are located in an intermediate range M between the terminals 13A and 13B in the first direction, and therefore the portion where the third weld mark overlaps the first weld mark is located in the intermediate range M. In the battery 1, the fourth weld mark overlaps the first weld mark at corner 25, and the fourth weld mark overlaps the second weld mark at corner 26. The fifth weld mark overlaps the third weld mark at corner 27, and the fifth weld mark overlaps the second weld mark at corner 28.

[0036] FIG. 6 shows an example of a portion where one weld mark 32 overlaps another weld mark 31 in the welded portion 30 of the lid member 5 to the outer container 3. In the example shown in FIG. 6, after the weld mark 31 is formed by laser welding, the weld mark 32 overlaps the weld mark 31 by a subsequent laser welding. The overlapping weld mark 31 of the two weld marks 31, 32 is, for example, a first laser mark formed by the first laser welding, and the overlapping weld mark 32 of the two weld marks 31, 32 is, for example, a third laser mark formed by the third laser welding. In the portion where the weld mark 32 overlaps the weld mark 31, both the overlapping weld mark 31 and the overlapping weld mark 32 are visible in a cut cross section. Therefore, in the battery 1, both the overlapping weld mark 31 and the overlapping weld mark 32 are visible.

[0037] Here, when welding the lid member 5 to the outer container 3, the weld mark 31 is formed by laser welding, and the light reflectivity on the surface of the portion where the weld mark 31 is formed is higher than before the weld mark 31 was formed. When the weld mark 32 overlaps the weld mark 31, laser welding is performed on the portion where the light reflectivity on the surface has been increased by the weld mark 31. For this reason, when further laser welding is performed on the portion where the weld mark 31 is formed, the laser output is lowered and the penetration depth of the laser welding becomes shallower. For this reason, in the portion where the weld mark 32 overlaps the weld mark 31, the weld mark 32 formed by the later laser welding is shallower and wider than the weld mark 31 formed by the earlier laser welding. For this reason, in the portion where the weld mark 32 overlaps the weld mark 31, the weld marks 31 and 32 can be distinguished from each other in a cut cross section.

[0038] Furthermore, when welding is performed by laser welding, a start mark indicating the start point of the laser welding and an end mark indicating the end point of the laser welding are formed in the weld mark. FIG. 7 shows an example of a weld mark 35 formed by laser welding. In the example of FIG. 7, welding is performed from the start point to the end point along the arrow A0. In the weld mark 35 formed by laser welding, multiple spot marks 36 are connected in the direction of the arrow A0. The weld mark 35 extends from the extended end Q1 to the extended end Q2. In the weld mark 35, a start mark 37 is formed at the end on the side where the extended end Q1 is located, and an end mark 38 is formed at the end on the side where the extended end Q2 is located. In the start mark 37, the spot mark 36 forming the extended end Q1 overlaps with an adjacent spot mark 36. On the other hand, in the end mark 38, the spot mark 36 forming the extended end Q2 does not overlap with another spot mark 36. Therefore, it becomes possible to identify the start mark 37 and the end mark 38 in the weld mark 35, and from the start mark 37 and the end mark 38, it becomes possible to recognize the start point and the end point of the laser welding that formed the weld mark 35.

[0039] In battery 1, an end mark indicating the end mark of the third laser welding that formed the third weld mark is formed at midpoint (second midpoint) α2. In addition, one of the start mark and end mark of the fourth laser welding is formed at corner 25, and the other of the start mark and end mark of the fourth laser welding is formed at corner 26. Then, one of the start mark and end mark of the fifth laser welding is formed at corner 27, and the other of the start mark and end mark of the fifth laser welding is formed at corner 28. Therefore, in battery 1, the end mark of the third laser welding, the start and end marks of the fourth laser welding, and the start and end marks of the fifth laser welding can be recognized from the welded portion of lid member 5 to outer container 3.

[0040] In Battery 1, the start and end marks of the first laser welding cannot be identified because the third and fourth welding marks overlap the first welding mark. Similarly, the start and end marks of the second laser welding cannot be identified because the fourth and fifth welding marks overlap the second welding mark. And the start mark of the third laser welding cannot be identified because the fifth welding mark overlaps the third welding mark.

[0041] In this embodiment, since the lid member 5 is welded to the outer container 3 as described above, the adjacent portion P1 is welded by the first laser welding, and then the adjacent portion P2 is welded by the second laser welding. This shortens the time from when the adjacent portion P1 is welded to when the adjacent portion P2 is welded, thereby reducing the temperature rise in the terminal 13A and its vicinity due to the heat generated by welding. Furthermore, in this embodiment, the adjacent portion P4 is welded by the second laser welding, and then the adjacent portion P3 is welded by the third laser welding. This shortens the time from when the adjacent portion P4 is welded to when the adjacent portion P3 is welded, thereby reducing the temperature rise in the terminal 13B and its vicinity due to the heat generated by welding.

[0042] As described above, in this embodiment, even if the distance from the welded portion of the lid member 5 to the outer container 3 to terminal 13A, and the insulator 16 and gasket 17 corresponding to terminal 13A, respectively, is reduced, the influence of heat generated by welding the lid member 5 to the outer container 3 on gasket 17, insulator 16, etc. is reduced. Furthermore, even if the distance from the welded portion of the lid member 5 to the outer container 3 to terminal 13B, and the insulator 16 and gasket 17 corresponding to terminal 13B, respectively, is reduced, the influence of heat generated by welding the lid member 5 to the outer container 3 on gasket 17, insulator 16, etc. is reduced. Therefore, even if the volume of each of terminals 13A and 13B is increased and the battery 1 is made larger in current, the influence of heat generated by welding to each of the pair of gaskets 17 and the pair of insulators 16 is appropriately reduced.

[0043] When lid member 5 is welded to outer container 3, the effect of heat generated by welding gasket 17 and insulator 16 is reduced, and therefore, in the manufactured battery 1, the sealing performance of gasket 17 is appropriately ensured at the attachment portions of terminals 13A and 13B to lid member 5. Furthermore, when lid member 5 is welded to outer container 3, the effect of heat generated by welding gasket 17 and insulator 16 is reduced, and therefore, in the manufactured battery 1, each of terminals 13A and 13B is appropriately insulated from lid member 5 by the corresponding one of insulator 16 and the corresponding one of gasket 17. As described above, in battery 1 of this embodiment, a large current can be achieved by increasing the volume of terminals 13A and 13B, and the effect of heat generated by welding on gasket 17 and the like is reduced when lid member 5 is welded to outer container 3 during manufacturing.

[0044] In this embodiment, the second laser welding starts at corner 26, passes through edge 21B, and ends at corner 28. This further shortens the time from when adjacent portion P1 is welded to when adjacent portion P2 is welded, further reducing the impact of heat generated by welding on gasket 17 and other components corresponding to terminal 13A. In addition, the third laser welding starts at corner 27, passes through adjacent portion P3 of edge 21A, and ends at midpoint α2. This further shortens the time from when adjacent portion P4 is welded to when adjacent portion P3 is welded, further reducing the impact of heat generated by welding on gasket 17 and other components corresponding to terminal 13B.

[0045] In a modification of the first embodiment, during the manufacture of the battery 1, the lid member 5 is welded to the outer casing 3 as shown in Fig. 8. In the modification of Fig. 8, laser welding is performed eight times to weld the lid member 5 to the outer casing 3.

[0046] In the first laser welding, welding is performed between midpoint (seventh midpoint) β1 of edge (first edge) 21A and corner (first corner) 25 through the adjacent portion (first adjacent portion) P1. At this time, in one example, welding is performed in the direction of arrow B1, i.e., from midpoint β1 toward corner 25. In another example, welding is performed in the opposite direction of arrow B1, i.e., from corner 25 toward midpoint β1.

[0047] In the second laser welding, welding is performed between midpoint (eighth midpoint) β2 of edge (second edge) 21B and corner (second corner) 26 through the adjacent portion (second adjacent portion) P2. At this time, in one example, welding is performed in the direction of arrow B2, i.e., from corner 26 toward midpoint β2. In another example, welding is performed in the opposite direction of arrow B2, i.e., from midpoint β2 toward corner 26.

[0048] In the third laser welding, welding is performed between the midpoint (ninth midpoint) β3 of the edge (first edge) 21A and the corner (third corner) 27 through the proximal portion (third proximal portion) P3. The midpoint β3 is located on the side of the corner 27 relative to the midpoint β1. In the example shown in FIG. 8 , the midpoints β1 and β3 are located in the intermediate range M between the terminals 13A and 13B in the first direction. In one example, welding is performed in the direction of the arrow B3, i.e., from the corner 27 toward the midpoint β3. In another example, welding is performed in the opposite direction to the arrow B3, i.e., from the midpoint β3 toward the corner 27.

[0049] In the fourth laser welding, welding is performed between the corner (fourth corner) 28 and a midpoint (tenth midpoint) β4 of the edge (second edge) 21B through the adjacent portion (fourth adjacent portion) P4. The midpoint β4 is located on the side of the corner 28 relative to the midpoint β2. In the example shown in FIG. 8 , the midpoints β2 and β4 are located in the intermediate range M. In one example, welding is performed in the direction of arrow B4, i.e., from the midpoint β4 toward the corner 28. In another example, welding is performed in the opposite direction to the arrow B4, i.e., from the corner 28 toward the midpoint β4.

[0050] In the fifth to eighth laser welding, one of the following four laser welding patterns φ1 to φ4 is performed. Each of the laser welding patterns φ1 to φ4 may be performed in any one of the fifth to eighth laser welding patterns, and the order in which the laser welding patterns φ1 to φ4 are performed is not particularly limited.

[0051] The laser welding φ1 is performed on the edge (first edge) 21A between an intermediate position (eleventh intermediate position) β5 and an intermediate position (twelfth intermediate position) β6. In one example, welding is performed in the direction of arrow B5, i.e., from intermediate position β5 to intermediate position β6. In another example, welding is performed in the opposite direction to arrow B5, i.e., from intermediate position β6 to intermediate position β5. The intermediate position β5 is located on the side where corner 27 is located relative to intermediate position β3, and the intermediate position β6 is located on the side where corner 25 is located relative to intermediate position β1. Therefore, between intermediate positions β3 and β5 on the edge (first edge) 21A, the laser welding φ1 is further performed overlapping the welded portion where the third laser welding was performed, and between intermediate positions β1 and β6 on the edge 21A, the laser welding φ1 is further performed overlapping the welded portion where the first laser welding was performed. 8, the portion where laser welding φ1 is performed overlapping the first laser welding, i.e., the portion of edge 21A between midpoints β1 and β6, is located in intermediate range M. Furthermore, the portion where laser welding φ1 is performed overlapping the third laser welding, i.e., the portion of edge 21A between midpoints β3 and β5, is located in intermediate range M.

[0052] The laser welding φ2 is performed on the edge (second edge) 21B between the midpoint (thirteenth midpoint) β7 and the midpoint (fourteenth midpoint) β8. In one example, welding is performed in the direction of arrow B6, i.e., from the midpoint β7 to the midpoint β8. In another example, welding is performed in the opposite direction to arrow B6, i.e., from the midpoint β8 to the midpoint β7. The midpoint β7 is located on the side of the corner 26 relative to the midpoint β2, and the midpoint β8 is located on the side of the corner 28 relative to the midpoint β4. Therefore, between the midpoints β2 and β7 on the edge (second edge) 21B, the laser welding φ2 is further performed overlapping the welded portion where the second laser welding was performed, and between the midpoints β4 and β8 on the edge 21B, the laser welding φ2 is further performed overlapping the welded portion where the fourth laser welding was performed. 8, the portion where laser welding φ2 overlaps with the second laser welding, i.e., the portion of edge 21B between midpoints β2 and β7, is located in intermediate range M. Furthermore, the portion where laser welding φ2 overlaps with the fourth laser welding, i.e., the portion of edge 21B between midpoints β4 and β8, is located in intermediate range M.

[0053] Laser welding φ3 is performed between corner (first corner) 25 and corner (second corner) 26, passing through edge (third edge) 22A. At this time, in one example, welding is performed in the direction of arrow B7, i.e., from corner 26 toward corner 25. In another example, welding is performed in the opposite direction of arrow B7, i.e., from corner 25 toward corner 26. At corner 25, laser welding φ3 is performed again on the welded portion where the first laser welding was performed. Then, at corner 26, laser welding φ3 is performed again on the welded portion where the second laser welding was performed.

[0054] The laser welding φ4 is performed between the corner (third corner) 27 and the corner (fourth corner) 28, passing through the edge (fourth edge) 22B. At this time, in one example, welding is performed in the direction of arrow B8, i.e., from corner 28 toward corner 27. In another example, welding is performed in the opposite direction to arrow B8, i.e., from corner 27 toward corner 28. At corner 27, laser welding φ4 is further performed overlapping the welded portion where the third laser welding was performed. At corner 28, laser welding φ4 is further performed overlapping the welded portion where the fourth laser welding was performed.

[0055] As described above, the lid member 5 is welded to the outer container 3, and in this modified example, eight weld marks are formed in the welded portion of the lid member 5 to the outer container 3. The first weld mark corresponding to the first laser welding extends between midpoint β1 of the edge 21A and corner 25 through adjacent portion P1, the second weld mark corresponding to the second laser welding extends between corner 26 and midpoint β2 through adjacent portion P2, the third weld mark corresponding to the third laser welding extends between corner 27 and midpoint β3 through adjacent portion P3, and the fourth weld mark corresponding to the fourth laser welding extends between corner 28 and midpoint β4 through adjacent portion P4. The fifth weld mark corresponding to laser weld φ1 extends between intermediate positions β5 and β6 on edge 21A, passing through intermediate positions β1 and β3, and the sixth weld mark corresponding to laser weld φ2 extends between intermediate positions β7 and β8 on edge 21B, passing through intermediate positions β2 and β4. The seventh weld mark corresponding to laser weld φ3 extends between corners 25 and 26 through edge 22A, and the seventh weld mark corresponding to laser weld φ4 extends between corners 27 and 28 through edge 22B.

[0056] In the battery 1 of this modification, at the welded portion of the lid member 5 to the outer container 3, the fifth weld mark overlaps the first weld mark between midpoints β1 and β6 on the edge 21A, and the fifth weld mark overlaps the third weld mark between midpoints β3 and β5 on the edge 21A. Then, the sixth weld mark overlaps the second weld mark between midpoints β2 and β7 on the edge 21B, and the sixth weld mark overlaps the fourth weld mark between midpoints β4 and β8 on the edge 21B. 8, the portion where the fifth weld mark overlaps the first weld mark, the portion where the fifth weld mark overlaps the third weld mark, the portion where the sixth weld mark overlaps the second weld mark, and the portion where the sixth weld mark overlaps the fourth weld mark are each located in an intermediate range M between terminals 13A and 13B in the first direction. Furthermore, in battery 1, the seventh weld mark overlaps the first weld mark at corner 25, and the seventh weld mark overlaps the second weld mark at corner 26. Furthermore, the eighth weld mark overlaps the third weld mark at corner 27, and the eighth weld mark overlaps the fourth weld mark at corner 28.

[0057] In battery 1 of this modified example, one of the start mark and end mark of laser welding φ1, which formed a fifth weld mark, is formed at midpoint β5, and the other of the start mark and end mark of laser welding φ1 is formed at midpoint β6. Then, one of the start mark and end mark of laser welding φ2, which formed a sixth weld mark, is formed at midpoint β7, and the other of the start mark and end mark of laser welding φ2 is formed at midpoint β8. Also, one of the start mark and end mark of laser welding φ3 is formed at corner 25, and the other of the start mark and end mark of laser welding φ3 is formed at corner 26. Then, one of the start mark and end mark of laser welding φ4 is formed at corner 27, and the other of the start mark and end mark of laser welding φ4 is formed at corner 28.

[0058] In this modification, after the adjacent portion P1 is welded by the first laser welding, the adjacent portion P2 is welded by the second laser welding. This shortens the time from when the adjacent portion P1 is welded until the adjacent portion P2 is welded, thereby reducing the temperature rise in terminal 13A and its vicinity due to the heat generated by welding. Also, in this modification, after the adjacent portion P3 is welded by the third laser welding, the adjacent portion P4 is welded by the fourth laser welding. This shortens the time from when the adjacent portion P3 is welded until the adjacent portion P4 is welded, thereby reducing the temperature rise in terminal 13B and its vicinity due to the heat generated by welding.

[0059] As described above, in this modification as well, even if the distance from the welded portion of the lid member 5 to the outer container 3 to terminal 13A, and to insulator 16 and gasket 17 corresponding to terminal 13A, respectively, is reduced, the influence of heat generated by welding the lid member 5 to the outer container 3 on gasket 17, insulator 16, etc. is reduced. Furthermore, even if the distance from the welded portion of the lid member 5 to the outer container 3 to terminal 13B, and to insulator 16 and gasket 17 corresponding to terminal 13B, respectively, is reduced, the influence of heat generated by welding the lid member 5 to the outer container 3 on gasket 17, insulator 16, etc. is reduced. Therefore, in this modification as well, it is possible to increase the volume of terminals 13A and 13B, thereby achieving a larger current, and the influence of heat generated by welding the lid member 5 to the outer container 3 during manufacturing is reduced on gasket 17, etc.

[0060] 5 etc., and the modified example shown in FIG. 8, at least a proximal portion (first proximal portion) P1 of edge (first edge) 21A is welded in the first laser welding, and one or more start points and one or more end points of the multiple laser weldings are located in the intermediate range M. Then, at least a proximal portion (second proximal portion) P2 of edge (second edge) 21B is welded in the second laser welding, and at least a proximal portion (third proximal portion) P3 of edge 21A is welded in the third laser welding.

[0061] In each of the battery 1 formed by welding according to the first embodiment shown in Fig. 5 etc. and the battery 1 formed by welding according to the modified example shown in Fig. 8, the multiple weld marks forming the welded portion of the lid member 5 to the outer container 3 include a first weld mark extending through a proximal portion P1 of the edge 21A, and one extending end of the first weld mark is located in an intermediate range M between the terminals 13A and 13B in the first direction. Another weld mark among the multiple weld marks overlaps a portion of the first weld mark at the edge 21A. The multiple weld marks of the welded portion include a second weld mark extending through a proximal portion P2 of the edge 21B and a third weld mark extending through a proximal portion P3 of the edge 21A.

[0062] 8, it is possible to shorten the time from welding the adjacent portion P1 to welding the adjacent portion P2, and to shorten the time from welding one of the adjacent portions P3, P4 to welding the other of the adjacent portions P3, P4. Therefore, even if the increased volume of each of the terminals 13A, 13B increases the current capacity of the battery 1 and forms the adjacent portions P1, P3 of the edge 21A and the adjacent portions P2, P4 of the edge 21B, the effects of heat generated by welding to the gasket 17 and the insulator 16 are appropriately reduced.

[0063] In a second embodiment, which is a modification of the first embodiment, during the manufacture of the battery 1, the lid member 5 is welded to the outer casing 3 as shown in Fig. 9. In the second embodiment, laser welding is performed twice to weld the lid member 5 to the outer casing 3. As a result, a first weld mark corresponding to the first laser welding and a second weld mark corresponding to the second laser welding are formed in the welded portion of the lid member 5 to the outer casing 3 of the battery 1.

[0064] In the first laser welding, welding is performed from midpoint (third midpoint) γ1 of edge (first edge) 21A to midpoint (fourth midpoint) γ2 of edge (second edge) 21B, passing through proximal portion (first proximal portion) P1, corner (first corner) 25, edge (third edge) 22A, corner (second corner) 26, and proximal portion (second proximal portion) P2 in that order. Therefore, in the first laser welding, welding is performed in the order of proximal portion P1 of edge 21A, edge 22A, and proximal portion P2 of edge 21B, with midpoint γ1 as the starting point and midpoint γ2 as the end point.

[0065] In the second laser welding, welding is performed from midpoint (fifth midpoint) γ3 of edge (first edge) 21A to midpoint (sixth midpoint) γ4 of edge (second edge) 21B, passing through proximal portion (third proximal portion) P3, corner (third corner) 27, edge (fourth edge) 22B, corner (fourth corner) 28, and proximal portion (fourth proximal portion) P4 in this order. Therefore, in the second laser welding, welding is performed in the order of proximal portion P3 of edge 21A, edge 22B, and proximal portion P4 of edge 21B, starting from midpoint γ3 and ending at midpoint γ4. Midpoint γ3 is located on the side of edge 21A where corner 25 is located relative to midpoint γ1. Midpoint γ4 is located on the side of edge 21B where corner 26 is located relative to midpoint γ2.

[0066] Between midpoints γ1 and γ3 on edge (first edge) 21A and between midpoints γ2 and γ4 on edge (second edge) 21B, second laser welding is performed to overlap the welded portions where the first laser welding was performed. In the example of Fig. 9, midpoints γ1 to γ4 are located in an intermediate range M between terminals 13A and 13B in the first direction. Therefore, the portions where the second laser welding is performed overlapping the first laser welding, i.e., the portion between midpoints γ1 and γ3 on edge 21A and the portion between midpoints γ2 and γ4 on edge 21B, are located in the intermediate range M.

[0067] As described above, the lid member 5 is welded to the outer container 3, and in this embodiment, two weld marks are formed in the welded portion of the lid member 5 to the outer container 3. The first weld mark, which corresponds to the first laser welding, extends between midpoint γ1 on edge 21A and midpoint γ2 on edge 21B, passing through adjacent portion P1, corner 25, edge 22A, corner 26, and adjacent portion P2. The second weld mark, which corresponds to the second laser welding, is formed between midpoint γ3 on edge 21A on the side where corner 25 is located relative to midpoint γ1, and midpoint γ4 on edge 21B on the side where corner 26 is located relative to midpoint γ2. The second weld mark then extends through adjacent portion P3, corner 27, edge 22B, corner 28, and adjacent portion P4.

[0068] Furthermore, in the battery 1 of this embodiment, the second weld mark overlaps the first weld mark at each of the edges 21A and 21B in the welded portion of the lid member 5 to the outer container 3. That is, the second weld mark overlaps the first weld mark between midpoints γ1 and γ3 at edge 21A and between midpoints γ2 and γ4 at edge 21B. Furthermore, in the battery 1 of this modification, the start mark of the second laser welding that formed the second weld mark is formed at midpoint γ3, and the end mark of the second laser welding is formed at midpoint γ4.

[0069] In this embodiment, the first laser welding welds the adjacent portion P1 and then the adjacent portion P2 in this order. This shortens the time from when the adjacent portion P1 is welded until the adjacent portion P2 is welded, thereby reducing the temperature rise in terminal 13A and its vicinity due to the heat generated by welding. Also, in this embodiment, the second laser welding welds the adjacent portion P3 and then the adjacent portion P4 in this order. This shortens the time from when the adjacent portion P3 is welded until the adjacent portion P4 is welded, thereby reducing the temperature rise in terminal 13B and its vicinity due to the heat generated by welding.

[0070] As described above, in this embodiment as well, even if the distance from the welded portion of the lid member 5 to the outer container 3 to terminal 13A, and to insulator 16 and gasket 17 corresponding to terminal 13A, respectively, is reduced, the influence of heat generated by welding the lid member 5 to the outer container 3 on gasket 17, insulator 16, etc. is reduced. Furthermore, even if the distance from the welded portion of the lid member 5 to the outer container 3 to terminal 13B, and to insulator 16 and gasket 17 corresponding to terminal 13B, respectively, is reduced, the influence of heat generated by welding the lid member 5 to the outer container 3 on gasket 17, insulator 16, etc. is reduced. Therefore, in this embodiment as well, it is possible to achieve a larger current by increasing the volume of terminals 13A and 13B, and the influence of heat generated by welding on gasket 17, etc. is reduced when the lid member 5 is welded to the outer container 3 during manufacturing.

[0071] In any of the above-described embodiments, at least a proximal portion (first proximal portion) P1 of edge (first edge) 21A is welded in the first laser welding, and one or more start points and one or more end points of the multiple laser weldings are located in intermediate range M. Also, in any of the above-described embodiments of battery 1, the multiple weld marks forming the welded portion of lid member 5 to outer container 3 include a first weld mark that extends through proximal portion P1 of edge 21A, and one extended end of the first weld mark is located in intermediate range M between terminals 13A and 13B in the first direction. Furthermore, a weld mark other than the first weld mark among the multiple weld marks overlaps a portion of the first weld mark at edge 21A.

[0072] By performing welding in a manner similar to any of the above-described embodiments, it is possible to shorten the time from welding adjacent portion P1 to welding adjacent portion P2, and to shorten the time from welding one of adjacent portions P3, P4 to welding the other of adjacent portions P3, P4. Therefore, even if the battery 1 is made larger in current by increasing the volume of each of terminals 13A, 13B, and adjacent portions P1, P3 of edge 21A and adjacent portions P2, P4 of edge 21B are formed, the effects of heat generated by welding to gasket 17 and insulator 16 are appropriately reduced.

[0073] Here, as a verification related to the embodiments, a simulation analysis was performed to calculate the change in temperature over time of a gasket 17 disposed at an attachment portion of a terminal 13A when a lid member 5 was attached to an outer casing 3. In the verification, the change in temperature over time of the gasket 17 was calculated for each of the following cases: welding in the same manner as in the first embodiment shown in FIG. 5 etc.; meltdown in the same manner as in the second embodiment shown in FIG. 9 etc.; and welding in the comparative example shown in FIG. 10. In the comparative example, as shown in FIG. 10, laser welding was performed only once to weld the lid member 5 to the outer casing 3. In one laser welding, welding was performed in the following order from a start point ε1 of a corner (first corner) 25 to an edge (third edge) 22A, a corner (second corner) 26, an edge (second edge) 21B, a corner (fourth corner) 28, an edge (fourth edge) 22B, a corner (third corner) 27, and an edge (first edge) 21A. Then, after welding the outer periphery of the cover member 5 once, the edge 22A was welded beyond the corner 25, and the welding was continued up to the end point ε2 of the corner .

[0074] In a simulation, the maximum temperature of the gasket 17 during welding was lower when the gasket 17 was welded according to the first embodiment and the second embodiment than when the gasket 17 was welded according to the comparative example, and the temperature rise of the gasket 17 due to the heat generated by welding was reduced. In the comparative example, the time from welding the adjacent portion P2 of the edge 21B to welding the adjacent portion P1 of the edge 21A was longer, so the temperature of the gasket 17 increased, especially when the adjacent portion P1 was being welded. In fact, the maximum temperature of the gasket 17 during welding was lower by about 15% when the gasket 17 was welded according to the first embodiment and by about 12% when the gasket 17 was welded according to the second embodiment than when the gasket 17 was welded according to the comparative example.

[0075] In another verification related to the embodiments, the temperature was measured around the periphery of the through hole 15 formed in the attachment portion of the terminal 13A when the lid member 5 was attached to the outer container 3. In the verification, the temperature around the periphery of the through hole 15 was measured for both the case where the welding was performed in the same manner as in the first embodiment shown in FIG. 5 etc., and the case where the welding was performed in the comparative example shown in FIG. 10. In the verification, the temperature increase around the periphery of the through hole 15 from the state before welding was reduced when the welding was performed in the first embodiment compared to when the welding was performed in the comparative example. In fact, the temperature increase around the periphery of the through hole 15 due to welding was reduced by 10.6°C when the welding was performed in the first embodiment compared to when the welding was performed in the comparative example.

[0076] According to at least one of these embodiments or examples, a pair of terminals is attached to a lid member having an outer periphery formed by first and second edges along a first direction and third and fourth edges along a second direction intersecting the first direction, with the second terminal spaced from the first terminal toward the side where the fourth edge is located in the first direction, and a first proximal portion closer to the first terminal than the third edge is formed on the first edge. Then, the entire outer periphery of the lid member is welded to the outer container by multiple laser welding passes. The first laser welding passes welds at least the first proximal portion, and one or more start points and one or more end points of the multiple laser welding passes are located in a mid-range between the first and second terminals in the first direction. This allows for increased terminal volume, enabling a battery capable of handling large currents, and reducing the impact of heat generated during welding of the lid member to the outer container on the gasket and other components, as well as a method for manufacturing such a battery.

[0077] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. The following are additional notes. [1] forming an outer container having an internal cavity that opens to the outside; forming a cover member having a first edge and a second edge along a first direction, and a third edge and a fourth edge along a second direction intersecting the first direction, which form an outer periphery; attaching the first terminal and the second terminal to the cover member while separating the second terminal from the first terminal toward a side where the fourth edge is located in the first direction, and forming a first proximity portion on the first edge that is closer to the first terminal than the third edge; storing an electrode group electrically connected to the first terminal and the second terminal in the internal cavity of the outer container, and closing an opening of the internal cavity with the lid member; welding the outer periphery of the lid member to the outer container along the entire periphery by performing laser welding a plurality of times on the lid member that closes the opening of the internal cavity, wherein at least the first adjacent portion of the first edge is welded by a first laser welding, and one or more start points and one or more end points of the plurality of laser weldings are positioned in an intermediate range between the first terminal and the second terminal in the first direction; A method for manufacturing a battery, comprising: [2] By attaching the first terminal and the second terminal to the cover member, a second adjacent portion closer to the first terminal than the third edge is formed on the second edge, and a third adjacent portion closer to the second terminal than the fourth edge is formed on the first edge; welding at least the second adjacent portion of the second edge with a second laser weld in the plurality of laser welds; welding at least the third adjacent portion of the first edge by a third laser welding of the plurality of laser weldings; [1] Manufacturing method. [3] In forming the lid member, a first corner is formed between the first edge and the third edge, a second corner is formed between the second edge and the third edge, a third corner is formed between the first edge and the fourth edge, and a fourth corner is formed between the second edge and the fourth edge, In the first laser welding, welding is performed between a first intermediate position of the first edge and the first corner portion through the first adjacent portion; the second laser welding is performed from the second corner to the fourth corner through the second edge including the second adjacent portion; In the third laser welding, welding is performed from the third corner portion through the third proximal portion and the first intermediate position in this order to a second intermediate position on the first edge on the side where the first corner portion is located with respect to the first intermediate position, a fourth laser welding among the plurality of laser weldings, welding between the first corner portion and the second corner portion through the third edge; a fifth laser welding among the plurality of laser weldings, welding between the third corner portion and the fourth corner portion through the fourth edge; [2] Manufacturing method. [4] The first intermediate position is located in the intermediate range, The second intermediate position is located on the side where the first corner portion is located relative to the first intermediate position in the intermediate range. [3] Manufacturing method. [5] By attaching the first terminal to the cover member, a second proximal portion is formed on the second edge, the second proximal portion being closer to the first terminal than the third edge; By attaching the second terminal to the cover member, a third proximal portion closer to the second terminal than the fourth edge is formed on the first edge, and a fourth proximal portion closer to the second terminal than the fourth edge is formed on the second edge; the first laser welding is performed in the order of the first adjacent portion of the first edge, the third edge, and the second adjacent portion of the second edge; a second laser welding of the plurality of laser weldings sequentially welding the third adjacent portion of the first edge, the fourth edge, and the fourth adjacent portion of the second edge; [1] Manufacturing method. [6] In forming the lid member, a first corner is formed between the first edge and the third edge, a second corner is formed between the second edge and the third edge, a third corner is formed between the first edge and the fourth edge, and a fourth corner is formed between the second edge and the fourth edge, In the first laser welding, welding is performed from a third midpoint of the first edge to a fourth midpoint of the second edge, passing through the first proximal portion, the first corner portion, the third edge, the second corner portion, and the second proximal portion in this order; In the second laser welding, welding is performed from a fifth midpoint on the first edge on a side where the first corner portion is located relative to the third midpoint to a sixth midpoint on the second edge on a side where the second corner portion is located relative to the fourth midpoint, sequentially passing through the third adjacent portion, the third corner portion, the fourth edge, the fourth corner portion, and the fourth adjacent portion. [5] Manufacturing method. [7] The third intermediate position and the fourth intermediate position are located in the intermediate range, the fifth intermediate position is located on the side of the intermediate range where the first corner portion is located relative to the third intermediate position, the sixth intermediate position is located on the side of the intermediate range where the second corner portion is located relative to the fourth intermediate position; [6] Manufacturing method. [8] An outer container having an internal cavity that opens to the outside; a lid member that includes a first edge and a second edge along a first direction, and a third edge and a fourth edge along a second direction intersecting the first direction, and that has an outer periphery formed by the first edge, the second edge, the third edge, and the fourth edge, and that closes an opening of the internal cavity of the outer container; an electrode group housed in the internal cavity of the outer container; a first terminal attached to the cover member in a state electrically connected to the electrode group, the first proximal portion of the first edge being located closer than the third edge; a second terminal attached to the cover member in a state electrically connected to the electrode group, and disposed away from the first terminal on a side where the fourth edge is located in the first direction; a welded portion including a plurality of weld marks, the outer periphery of the lid member being welded to the outer container over the entire periphery by the plurality of weld marks, the plurality of weld marks including a first weld mark extending through the first adjacent portion of the first edge, one or both extending ends of the first weld mark being located in an intermediate range between the first terminal and the second terminal in the first direction, and a weld mark other than the first weld mark among the plurality of weld marks overlapping a portion of the first weld mark at the first edge; A battery comprising: [9] At the second edge, a second proximal portion is located closer to the first terminal than the third edge; At the first edge, a third proximate portion is located closer to the second terminal than the fourth edge; the plurality of weld marks of the welded portion include a second weld mark extending through the second adjacent portion of the second edge and a third weld mark extending through the third adjacent portion of the first edge. [8] Battery.

[10] The cover member has a first corner between the first edge and the third edge, a second corner between the second edge and the third edge, a third corner between the first edge and the fourth edge, and a fourth corner between the second edge and the fourth edge, the first weld mark extends between a first intermediate position of the first edge and the first corner portion through the first adjacent portion; the second weld mark extends between the second corner and the fourth corner through the second edge including the second adjacent portion; the third weld mark extends between the third corner portion and a second intermediate position on the first edge on the side where the first corner portion is located with respect to the first intermediate position, through the third adjacent portion and the first intermediate position; The third welding mark overlaps the first welding mark between the first midpoint and the second midpoint on the first edge, the welded portion includes a fourth weld mark extending through the third edge between the first corner and the second corner, and a fifth weld mark extending through the fourth edge between the third corner and the fourth corner. [9] Battery.

[11] The battery of

[10] , wherein an end mark indicating the end point of the laser welding that formed the third welding mark is formed at the second midpoint.

[12] At the second edge, a second proximal portion is located closer to the first terminal than the third edge; At the first edge, a third proximate portion is located closer to the second terminal than the fourth edge; At the second edge, a fourth proximal portion is located closer to the second terminal than the fourth edge; the first weld mark extends through the first adjacent portion of the first edge, the third edge, and the second adjacent portion of the second edge; the plurality of weld marks of the welded portion include a second weld mark extending through the third adjacent portion of the first edge, the fourth edge, and the fourth adjacent portion of the second edge; The second welding mark overlaps the first welding mark at each of the first edge and the second edge. [8] Battery.

[13] The cover member has a first corner between the first edge and the third edge, a second corner between the second edge and the third edge, a third corner between the first edge and the fourth edge, and a fourth corner between the second edge and the fourth edge, the first weld mark extends between a third intermediate position on the first edge and a fourth intermediate position on the second edge through the first adjacent portion, the first corner portion, the third edge, the second corner portion, and the second adjacent portion; the second weld mark extends through the third proximal portion, the third corner portion, the fourth edge, the fourth corner portion, and the fourth proximal portion between a fifth intermediate position on the first edge on a side where the first corner portion is located relative to the third intermediate position and a sixth intermediate position on the second edge on a side where the second corner portion is located relative to the fourth intermediate position, the second welding mark overlaps the first welding mark between the third midpoint and the fifth midpoint on the first edge, and between the fourth midpoint and the sixth midpoint on the second edge, respectively.

[12] Battery.

[14] A start mark indicating a start point of the laser welding that formed the second welding mark is formed at the fifth midpoint, An end mark indicating an end point of the laser welding that formed the second welding mark is formed at the sixth midpoint.

[13] Battery.

[15] Any one of the batteries [8] to

[14] , wherein the portion of the first weld mark where the other weld mark overlaps the first weld mark is located in the intermediate range.

Claims

1. forming an outer container having an internal cavity opening to the exterior; forming a cover member having a first edge and a second edge along a first direction, and a third edge and a fourth edge along a second direction intersecting the first direction, which form an outer periphery; attaching the first terminal and the second terminal to the cover member while separating the second terminal from the first terminal toward the side where the fourth edge is located in the first direction, and forming a first proximal portion on the first edge that is closer to the first terminal than the third edge, and a second proximal portion on the second edge that is closer to the first terminal than the third edge; storing an electrode group electrically connected to the first terminal and the second terminal in the internal cavity of the outer container, and closing an opening of the internal cavity with the lid member; welding the outer periphery of the lid member to the outer container along the entire periphery by performing laser welding a plurality of times on the lid member that closes the opening of the internal cavity, wherein at least the first adjacent portion of the first edge is welded by a first laser welding and at least the second adjacent portion of the second edge is welded by a second laser welding, and one or more start points and one or more end points of the plurality of laser weldings are positioned in an intermediate range between the first terminal and the second terminal in the first direction; A method for manufacturing a battery, comprising:

2. a third proximal portion is formed on the first edge by attaching the first terminal and the second terminal to the lid member, the third proximal portion being closer to the second terminal than the fourth edge; welding at least the third adjacent portion of the first edge by a third laser welding of the plurality of laser weldings; The method of claim 1.

3. In forming the lid member, a first corner is formed between the first edge and the third edge, a second corner is formed between the second edge and the third edge, a third corner is formed between the first edge and the fourth edge, and a fourth corner is formed between the second edge and the fourth edge, In the first laser welding, welding is performed between a first intermediate position of the first edge and the first corner portion through the first adjacent portion; the second laser welding is performed from the second corner to the fourth corner through the second edge including the second adjacent portion; In the third laser welding, welding is performed from the third corner portion through the third proximal portion and the first intermediate position in this order to a second intermediate position on the first edge on the side where the first corner portion is located with respect to the first intermediate position, a fourth laser welding among the plurality of laser weldings, welding between the first corner portion and the second corner portion through the third edge; a fifth laser welding among the plurality of laser weldings, welding between the third corner portion and the fourth corner portion through the fourth edge; The method of claim 2.

4. the first intermediate position is located in the intermediate range, the second intermediate position is located on a side of the intermediate range where the first corner portion is located relative to the first intermediate position; The method of claim 3.

5. By attaching the second terminal to the cover member, a third proximal portion closer to the second terminal than the fourth edge is formed on the first edge, and a fourth proximal portion closer to the second terminal than the fourth edge is formed on the second edge; the first laser welding is performed in the order of the first adjacent portion of the first edge, the third edge, and the second adjacent portion of the second edge; a second laser welding of the plurality of laser weldings is performed to weld the third adjacent portion of the first edge, the fourth edge, and the fourth adjacent portion of the second edge in this order; The method of claim 1.

6. In forming the lid member, a first corner is formed between the first edge and the third edge, a second corner is formed between the second edge and the third edge, a third corner is formed between the first edge and the fourth edge, and a fourth corner is formed between the second edge and the fourth edge, In the first laser welding, welding is performed from a third midpoint of the first edge to a fourth midpoint of the second edge, passing through the first proximal portion, the first corner portion, the third edge, the second corner portion, and the second proximal portion in this order; In the second laser welding, welding is performed from a fifth midpoint on the first edge on a side where the first corner portion is located relative to the third midpoint to a sixth midpoint on the second edge on a side where the second corner portion is located relative to the fourth midpoint, sequentially passing through the third adjacent portion, the third corner portion, the fourth edge, the fourth corner portion, and the fourth adjacent portion. The method of claim 5.

7. the third midpoint position and the fourth midpoint position are located in the intermediate range, the fifth midpoint is located on the side of the intermediate range where the first corner portion is located relative to the third midpoint, the sixth midpoint is located on the side of the intermediate range where the second corner portion is located relative to the fourth midpoint; The method of claim 6.

8. an outer container having an internal cavity that is open to the outside; a lid member having a first edge and a second edge along a first direction and a third edge and a fourth edge along a second direction intersecting the first direction, the lid member having an outer periphery formed by the first edge, the second edge, the third edge, and the fourth edge, the lid member closing an opening of the internal cavity of the outer container; an electrode group housed in the internal cavity of the outer container; a first terminal attached to the cover member in a state electrically connected to the electrode group, the first proximal portion of the first edge and the second proximal portion of the second edge being located closer to the third edge; a second terminal attached to the cover member in a state of being electrically connected to the electrode group, and disposed away from the first terminal on a side where the fourth edge is located in the first direction; a welded portion comprising a plurality of weld marks, the outer periphery of the lid member being welded to the outer container over the entire periphery by the plurality of weld marks, the plurality of weld marks comprising a first weld mark extending through the first adjacent portion of the first edge and a second weld mark extending through the second adjacent portion of the second edge, one or both extending ends of the first weld mark being located in an intermediate range between the first terminal and the second terminal in the first direction, and a weld mark other than the first weld mark among the plurality of weld marks overlapping a portion of the first weld mark at the first edge; A battery comprising:

9. At the first edge, a third proximal portion is located closer to the second terminal than the fourth edge; the plurality of weld marks of the welded portion include a third weld mark extending through the third adjacent portion of the first edge.

9. The battery of claim 8.

10. the cover member has a first corner between the first edge and the third edge, a second corner between the second edge and the third edge, a third corner between the first edge and the fourth edge, and a fourth corner between the second edge and the fourth edge, the first weld mark extends between a first intermediate position of the first edge and the first corner through the first adjacent portion; the second weld mark extends through the second edge including the second adjacent portion between the second corner and the fourth corner; the third welding mark extends between the third corner portion and a second intermediate position on the first edge on the side where the first corner portion is located with respect to the first intermediate position, through the third adjacent portion and the first intermediate position; the third welding mark overlaps the first welding mark between the first midpoint and the second midpoint on the first edge; the welded portion includes a fourth weld mark extending through the third edge between the first corner and the second corner, and a fifth weld mark extending through the fourth edge between the third corner and the fourth corner.

10. The battery of claim 9.

11. The battery of claim 10 , wherein an end mark indicating an end point of the laser welding that formed the third weld mark is formed at the second midpoint.

12. At the first edge, a third proximal portion is located closer to the second terminal than the fourth edge; At the second edge, a fourth proximate portion is located closer to the second terminal than the fourth edge; the first weld mark extends through the first adjacent portion of the first edge, the third edge, and the second adjacent portion of the second edge; the second weld mark extends through the third adjacent portion of the first edge, the fourth edge, and the fourth adjacent portion of the second edge; the second welding mark overlaps the first welding mark at each of the first edge and the second edge; 9. The battery of claim 8.

13. the cover member has a first corner between the first edge and the third edge, a second corner between the second edge and the third edge, a third corner between the first edge and the fourth edge, and a fourth corner between the second edge and the fourth edge, the first welding mark extends between a third intermediate position on the first edge and a fourth intermediate position on the second edge, passing through the first proximal portion, the first corner portion, the third edge, the second corner portion, and the second proximal portion; the second welding mark extends through the third proximal portion, the third corner portion, the fourth edge, the fourth corner portion, and the fourth proximal portion between a fifth intermediate position on the first edge on a side where the first corner portion is located relative to the third intermediate position and a sixth intermediate position on the second edge on a side where the second corner portion is located relative to the fourth intermediate position, the second welding mark overlaps the first welding mark between the third midpoint and the fifth midpoint on the first edge and between the fourth midpoint and the sixth midpoint on the second edge, respectively.

13. The battery of claim 12.

14. a start mark indicating a start point of the laser welding that formed the second welding mark is formed at the fifth midpoint; an end mark indicating an end point of the laser welding that formed the second welding mark is formed at the sixth midpoint; 14. The battery of claim 13.

15. The battery according to claim 8 , wherein a portion of the first weld mark where the other weld mark overlaps the first weld mark is located in the intermediate range.

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