Method for manufacturing power storage device, and power storage device

Abstract

The invention provides a method for manufacturing a power storage device and a power storage device. A method for manufacturing an electricity storage device includes a case preparation step, a sealing plate preparation step, an assembly step, and a formal welding step. In the case preparation step, a rectangular case having an opening is prepared. In the sealing plate preparation step, a sealing plate attached to the opening along the edge of the opening is prepared. In the assembling process, the sealing plate is installed on the opening of the shell. In the main welding step, the housing and the sealing plate are laser-welded over the entire periphery of the peripheral edge portion of the sealing plate. In the main welding step, the starting point of the laser welding is set at a position closer to the inner side than the peripheral edge part of the sealing plate.

Description

Technical Field

[0001] This invention relates to a method for manufacturing energy storage devices and to energy storage devices themselves. Background Technology

[0002] Japanese Patent Application Publication No. 2018-202478 discloses a laser welding apparatus comprising a unit for splitting a laser beam into two beams and a unit for moving the two split laser beams parallel to each other along the interface between two components. The apparatus is configured such that the two split laser beams are symmetrically positioned at equal distances from the interface, preventing them from entering the interface. According to Japanese Patent Application Publication No. 2018-202478, high-quality welding can be achieved when welding two components. For example, in the manufacture of a lithium battery comprising a container with an opening and a cap fitted to the opening and welded to the container, the laser welding apparatus described above can suppress sputtering.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2018-202478 Summary of the Invention

[0004] However, the inventors of this application wish to improve the bonding strength between the shell and the sealing plate.

[0005] The method for manufacturing an energy storage device disclosed herein includes: a step of preparing a square housing with an opening; a step of preparing a sealing plate to be installed along the edge of the opening; an assembly step of installing the sealing plate into the opening of the housing; and a formal welding step of laser welding the housing and the sealing plate around the periphery of the sealing plate. In the formal welding step, the starting point of the laser welding is set at a position inside the periphery of the sealing plate. According to this manufacturing method, the bonding strength between the housing and the sealing plate can be improved. Attached Figure Description

[0006] Figure 1 It is a schematic three-dimensional diagram representing an energy storage device.

[0007] Figure 2 It is an exploded 3D view of the energy storage device.

[0008] Figure 3 This is a flowchart illustrating an example of a method for manufacturing an energy storage device.

[0009] Figure 4 This is a diagram used to illustrate temporary welding procedures.

[0010] Figure 5 This is a diagram used to illustrate the formal welding process.

[0011] Figure 6 This is a schematic diagram showing the area near the starting point of laser welding in the formal welding process.

[0012] Figure 7 It is a schematic top view showing the shell and sealing plate after the formal welding process is completed.

[0013] Figure 8 It is Figure 7 An enlarged image of the area near the inner protrusion.

[0014] Figure 9 This is a schematic diagram representing the area near the starting point of laser welding in the formal welding process involved in other methods. Detailed Implementation

[0015] Hereinafter, one embodiment of the technology disclosed herein will be described with reference to the accompanying drawings. The embodiments described herein are not intended to specifically limit the invention. The drawings are schematic depictions and do not necessarily reflect the actual object. Furthermore, components and parts that perform the same function are appropriately labeled with the same reference numerals, and repeated descriptions are omitted where appropriate. In the drawings, reference numerals X, Y, and Z represent the front-back direction, left-right direction, and up-down direction, respectively. The Y direction is orthogonal to the X direction. The Z direction is orthogonal to both the X and Y directions. Reference numerals F, Rr, L, R, U, and D in the drawings refer to front, back, left, right, up, and down, respectively. However, these are merely directions for ease of explanation and do not limit the arrangement of the energy storage device. Additionally, unless specifically mentioned, the designations "X~Y" and similar terms indicating numerical ranges in this specification mean "X and above and Y and below".

[0016] In this specification, "energy storage device" refers to a device capable of charging and discharging. Energy storage devices include not only batteries commonly referred to as lithium-ion batteries or lithium secondary batteries, but also batteries such as lithium polymer batteries and nickel-metal hydride batteries. Secondary batteries typically refer to batteries that can be repeatedly charged and discharged through the movement of charge carriers between the positive and negative electrodes. Energy storage devices can use either liquid electrolytes or solid electrolytes. For example, a secondary battery can be either a secondary battery using a liquid electrolyte system or a so-called all-solid-state battery using a solid electrolyte. Additionally, energy storage devices also include capacitors such as double-layer capacitors and lithium-ion capacitors.

[0017] Figure 1 This is a schematic three-dimensional view of the energy storage device 10. Figure 2 This is an exploded perspective view of the energy storage device 10. (For example...) Figure 1 and Figure 2 As shown, the energy storage device 10 includes a housing 11 and a sealing plate 13.

[0018] The shell 11 is a square shell formed in a generally cuboid shape. When viewed from above, the shell 11 has a short side extending along the X direction and a long side extending along the Y direction. The shell 11 has a bottom surface 11a, a pair of narrow surfaces 11b, and a pair of wide surfaces 11c. The bottom surface 11a is formed as a rectangle with a short side and a long side. The pair of narrow surfaces 11b are opposite each other in the Y direction. The pair of narrow surfaces 11b extends upward from both ends of the bottom surface 11a in the Y direction. The pair of wide surfaces 11c are opposite each other in the X direction. The pair of wide surfaces 11c extends upward from both ends of the bottom surface 11a in the X direction. The pair of narrow surfaces 11b and the pair of wide surfaces 11c constitute the sides of the shell 11. Figure 2 As shown, the housing 11 has a rectangular opening 11d at the top. From the viewpoint of ensuring lightweight design and required rigidity, the housing 11 is formed, for example, of aluminum or an aluminum alloy primarily composed of aluminum. Although not shown in the figure, electrodes with positive and negative terminals are housed inside the housing 11. Furthermore, although not shown in the figure, in the case where the energy storage device 10 is a liquid-based battery, an electrolyte is also housed inside the housing 11.

[0019] The sealing plate 13 is a component used to block the opening 11d of the housing 11. The sealing plate 13 is installed along the edge of the opening 11d of the housing 11. Figure 1 In the arrangement shown, the sealing plate 13 is formed as a rectangular flat plate. The sealing plate 13 may also be formed of the same material as the housing 11. For example, the sealing plate 13 may also be formed of aluminum or an aluminum alloy.

[0020] The sealing plate 13 has an exhaust valve 14 for discharging gas from the interior of the housing 11. The exhaust valve 14 is located at the center of the sealing plate 13 in the Y direction. The exhaust valve 14 is, for example, a thin-walled portion designed to break when the internal pressure of the housing 11 rises above a predetermined value. When the internal pressure of the housing 11 reaches or exceeds the predetermined value, the exhaust valve 14 breaks, thereby discharging the gas inside the housing 11 to the outside of the housing 11.

[0021] Electrode terminals 17 are provided in pairs at both ends of the sealing plate 13 in the Y direction. The method of mounting the electrode terminals 17 to the sealing plate 13 is not particularly limited. For example, the electrode terminals 17 can also be mounted to the sealing plate 13 by riveting. Alternatively, the electrode terminals 17 can be integrally formed with the sealing plate 13. The electrode terminals 17 are electrically connected to an electrode body housed inside the housing 11. One of the pair of electrode terminals 17 is the positive terminal electrically connected to the positive electrode. The other of the pair of electrode terminals 17 is the negative terminal electrically connected to the negative electrode.

[0022] In such Figure 1In the energy storage device 10 shown, with the electrode body housed inside the housing 11, laser welding is performed on the housing 11 and the sealing plate 13 around its entire periphery 13a. This joins the housing 11 to the sealing plate 13, thereby sealing the interior of the housing 11. For example, in the case of a liquid-cooled battery, sealing the interior of the housing 11 prevents electrolyte leakage from inside the housing 11.

[0023] However, in the energy storage device 10 described above, the housing 11 sometimes expands due to factors such as the generation of gas accompanying charging and discharging. If the housing 11 expands, a load is applied to the joint between the housing 11 and the sealing plate 13. Therefore, a specified joint strength is required for the joint between the housing 11 and the sealing plate 13. However, the inventors of this application have confirmed that, particularly near the starting point of laser welding, it is sometimes impossible to ensure the specified joint strength at the joint between the housing 11 and the sealing plate 13. The inventors of this application have conducted in-depth research on the reasons for this and have considered the following.

[0024] Laser welding is a method of joining two components by irradiating the area near the boundary of the two parts to melt them. The joint strength depends on the weld depth, which is the depth of the molten portion within the components. A deeper weld depth results in higher joint strength, while a shallower weld depth results in lower joint strength. Therefore, to improve the joint strength between the housing 11 and the sealing plate 13, laser welding needs to be performed with a sufficiently deep weld depth. However, it is believed that immediately after the start of laser welding, the temperatures of the housing 11 and the sealing plate 13 may not rise sufficiently, resulting in incomplete melting of the housing 11 and the sealing plate 13. This is believed to cause the weld depth to sometimes be shallow near the starting point of the laser welding.

[0025] Furthermore, due to factors such as manufacturing dimensional tolerances, the positional relationship between the housing 11 and the sealing plate 13 and the laser used for laser welding sometimes deviates from the ideal positional relationship. Moreover, the ideal positional relationship mentioned here refers to the positional relationship between the housing 11 and the sealing plate 13 and the laser that is most suitable for proper laser welding. Additionally, when the sealing plate 13 is installed on the housing 11, gaps sometimes occur between the housing 11 and the sealing plate 13 due to factors such as manufacturing dimensional tolerances. According to the inventors' findings, when the laser is relatively deviated towards the housing 11 side compared to the ideal positional relationship, and a gap occurs between the housing 11 and the sealing plate 13, the joint strength tends to be lower near the starting point of laser welding. According to the inventors' findings, when the laser, housing 11, and sealing plate 13 are in this positional relationship, the sealing plate 13 is particularly difficult to melt immediately after the start of laser welding, therefore the weld depth tends to be shallow near the starting point of laser welding.

[0026] Furthermore, according to the inventors of this application, when manufacturing relatively large energy storage devices 10 with a housing 11 width of 30 cm or more, the welding depth near the starting point of laser welding tends to be particularly shallow. The inventors of this application understand the reasons for this as follows: When manufacturing relatively large energy storage devices 10, the dimensional tolerances of the housing 11 and the sealing plate 13 tend to increase, resulting in relatively large gaps between the housing 11 and the sealing plate 13. Compared to the ideal positional relationship, the laser tends to deviate significantly towards the housing 11 side. According to the inventors of this application, for example, when the housing 11 width is approximately 30 cm, a gap of approximately 0.2 mm sometimes occurs between the housing 11 and the sealing plate 13. Additionally, according to the inventors of this application, for example, when the housing 11 width is approximately 30 cm, the laser sometimes deviates relatively by approximately 0.2 mm towards the housing 11 side compared to the ideal positional relationship. Furthermore, in this specification, the width of the housing 11 refers to the length of the housing 11 in the Y direction.

[0027] Therefore, the inventors of this application desire to achieve a sufficiently deep weld throughout the entire circumference of the periphery 13a of the sealing plate 13, even when the laser, housing 11, and sealing plate 13 are in the positional relationship described above. More specifically, the inventors of this application desire to ensure that the sealing plate 13 is fully melted near the starting point of laser welding in the periphery 13a of the sealing plate 13, even when the laser, housing 11, and sealing plate 13 are in the positional relationship described above.

[0028] Figure 3 This is a flowchart illustrating an example of a method for manufacturing an energy storage device 10. The method for manufacturing the energy storage device 10 includes a housing preparation step S01, a sealing plate preparation step S02, an assembly step S03, a temporary welding step S04, and a formal welding step S05. Alternatively, the method for manufacturing the energy storage device 10 may omit the temporary welding step S04.

[0029] In the housing preparation step S01, a square housing 11 with an opening 11d is prepared. The method for preparing the housing 11 in the housing preparation step S01 is not particularly limited. The housing 11 can be prepared, for example, by bending a rectangular flat plate. The width of the housing 11 prepared in the housing preparation step S01 can also be 30 cm or more. By preparing such a relatively large housing, a relatively large electrode body can be housed inside the housing 11, thus enabling the acquisition of a high-capacity energy storage device.

[0030] In the sealing plate preparation process S02, a sealing plate 13 is prepared to be installed along the edge of the opening 11d of the housing 11. In the sealing plate preparation process S02, the sealing plate 13 with electrode terminals 17 are prepared. The method for preparing the sealing plate 13 in the sealing plate preparation process S02 is not particularly limited. For example, the sealing plate 13 can be prepared by machining a rectangular flat plate, such as by making a hole, and then installing the electrode terminals 17. Alternatively, the sealing plate 13 can be prepared by integrally forming it together with the electrode terminals 17. The sealing plate preparation process S02 can be performed before or after the housing preparation process S01. The sealing plate preparation process S02 can also be performed simultaneously with the housing preparation process S01.

[0031] In assembly step S03, the electrode body is inserted into the housing 11. Then, the sealing plate 13 is installed in the opening 11d of the housing 11.

[0032] Figure 4 This diagram illustrates the temporary welding process S04. Figure 4 The diagram shows the housing 11 and the sealing plate 13 as viewed from above. In the temporary welding step S04, with the sealing plate 13 installed in the opening 11d, a temporary weld is performed between the housing 11 and the sealing plate 13. This temporary welding is performed to position the sealing plate 13 relative to the housing 11. In the temporary welding step S04, the welding between the housing 11 and the sealing plate 13 is performed intermittently. Figure 4 In the illustrated method, temporary welding is performed at 16 predetermined locations along the boundary between the housing 11 and the sealing plate 13. Furthermore, Figure 4 The reference numerals W1 to W16 in the attached drawings indicate the locations where temporary welding is performed. Figure 4 In the manner shown, as indicated by reference numerals W1 to W4, temporary welding is performed at a predetermined location near the exhaust valve 14 at the boundary between the housing 11 and the sealing plate 13. Figure 4 In the illustrated manner, as indicated by reference numerals W5 to W12, temporary welding is performed at predetermined locations near the electrode terminals 17 within the boundary between the housing 11 and the sealing plate 13. However, the locations and number of temporary welds are not limited to [specific details needed]. Figure 4 The method shown can be appropriately modified according to the size of the housing 11 and the size of the sealing plate 13. Furthermore, the welding apparatus used in the temporary welding step S04 can be the same as or different from the welding apparatus used in the formal welding step S05. Various conventionally known welding apparatuses can also be used in the temporary welding step S04.

[0033] Figure 5 This diagram is used to illustrate the formal welding process S05. Figure 5The image shows the casing 11 and the sealing plate 13 as viewed from above. Figure 5 The arrow indicated by the reference WT in the attached diagram represents the welding trajectory in formal welding operation S05. (By...) Figure 5 The point indicated by reference numeral P1 in the attached drawing is the starting point of the formal welding. Furthermore, in the following description, the starting point of the formal welding is sometimes simply referred to as the starting point P1. In the formal welding step S05, the housing 11 and the sealing plate 13 are formally welded. The formal welding is performed to seal the opening 11d. In the formal welding step S05, laser welding is performed on the housing 11 and the sealing plate 13 along the entire circumference of the periphery 13a of the sealing plate 13. (As shown...) Figure 3 As shown, the formal welding process S05 includes a first process S05a and a second process S05b. Furthermore, various conventionally known laser welding apparatuses can also be used in the formal welding process S05.

[0034] Figure 6 This is a schematic diagram representing the area near the starting point P1. Figure 6 The reference numeral P2 in the attached drawing indicates the end point of the first step S05a. Furthermore, in the following description, the end point P2 of the first step S05a may sometimes be simply referred to as end point P2. Figure 6 In the attached diagram, reference numeral D1 represents the distance between the starting point P1 and the ending point P2. In the formal welding process S05, the starting point P1 for laser welding is set at a position inside the periphery 13a of the sealing plate 13. Figure 6 In the configuration shown, the starting point P1 is located to the left of the left electrode terminal 17. Figure 6 In the illustrated configuration, the starting point P1 is located at the center of the sealing plate 13 in the X direction. The ending point P2 is located at the periphery 13a of the sealing plate 13. The distance D1 between the starting point P1 and the ending point P2 corresponds to the distance for laser welding in the first step S05a. The distance D1 between the starting point P1 and the ending point P2 can be, for example, 0.5mm to 1.5mm. However, the distance D1 between the starting point P1 and the ending point P2 can be appropriately varied depending on factors such as the output value of the laser used for laser welding, the material of the sealing plate 13, and the welding speed.

[0035] In the first process S05a, laser welding is performed from the starting point P1 toward the periphery 13a of the sealing plate 13. Figure 6 In the method shown, in the first step S05a, laser welding is performed to the left from the starting point P1 to the ending point P2. Figure 6In the illustrated method, in the first step S05a, laser welding is performed with the welding trajectory WT perpendicular to the periphery 13a of the sealing plate 13. In the first step S05a, the laser output is controlled to increase as the welding position approaches the periphery 13a of the sealing plate 13 from the starting point P1. In the first step S05a, the laser output is controlled to reach a predetermined value when the welding position reaches the ending point P2.

[0036] Step 2 S05b is performed consecutively with step 1 S05a. In step 2 S05b, after step 1 S05a ends, laser welding is performed on the housing 11 and the sealing plate 13 along the entire circumference of the sealing plate 13's periphery 13a. In step 2 S05b, laser welding begins from the end point P2 of step 1 S05a. In step 2 S05b, the laser output is controlled to maintain it at a predetermined value. Figure 6 In the illustrated method, in the second step S05b, laser welding is performed clockwise, starting from the end point P2 of the first step S05a. Alternatively, in the second step S05b, laser welding can also be performed counterclockwise, starting from the end point P2 of the first step S05a. In the second step S05b, starting from the end point P2 of the first step S05a, the laser welder circles the periphery 13a of the sealing plate 13, returning to the end point P2 of the first step S05a, and then ends the laser welding. The second step S05b concludes, thus ending the formal welding step S05. When the formal welding step S05 concludes, the shell 11 and the sealing plate 13 are seamlessly welded, making the interior of the shell 11 sealed.

[0037] Figure 7 This is a schematic top view showing the shell 11 and sealing plate 13 after the formal welding process S05 is completed. Figure 7 In the diagram, the section with the cross-section line represents the weld mark 30 formed by laser welding performed in the formal welding process S05. Figure 7 The weld mark 30 is exaggeratedly shown in the image. The weld mark 30 forms around the entire circumference of the periphery 13a of the sealing plate 13. The weld mark 30 has an inner protrusion 30a and a main body 30b. (See image below.) Figure 7As shown, the main body 30b is formed in a ring shape around the periphery 13a of the sealing plate 13. The main body 30b is formed by laser welding performed in the second step S05b. The inner protrusion 30a is formed by protruding from the main body 30b. The inner protrusion 30a protrudes to a position inside the periphery 13a of the sealing plate 13. The inner protrusion 30a is formed by laser welding performed in the first step S05a.

[0038] Figure 8 It is Figure 7 An enlarged view of the vicinity of the inner protrusion 30a. Figure 8 The dashed line in the figure represents the periphery 13a of the sealing plate 13. Figure 8 In the attached drawing, reference numeral D2 is the distance from the periphery 13a of the sealing plate 13 to the end of the inner protrusion 30a. The distance D2 from the periphery 13a of the sealing plate 13 to the end of the inner protrusion 30a is the length of the weld mark formed by laser welding in the first process S05a.

[0039] exist Figure 6 Near the starting point P1, the temperature of the sealing plate 13 may not rise sufficiently, resulting in it not melting and sometimes no weld marks are formed. In this case, the distance D2 from the periphery 13a of the sealing plate 13 to the end of the inner protrusion 30a is shorter than the distance D1 between the starting point P1 and the ending point P2. On the other hand, when the temperature at the starting point P1 rises sufficiently, the sealing plate 13 melts at the starting point P1, thus forming weld marks there as well. Furthermore, in this case, sometimes the portion of the sealing plate 13 that is closer to the starting point P1 also melts, forming weld marks. In this case, the distance D2 from the periphery 13a of the sealing plate 13 to the end of the inner protrusion 30a may sometimes be greater than the distance D1 between the starting point P1 and the ending point P2. Based on these conditions, the distance D2 from the periphery 13a of the sealing plate 13 to the end of the inner protrusion 30a is sometimes shorter than, sometimes equal to, and sometimes longer than the distance D1 between the starting point P1 and the ending point P2. That is, the length of the weld mark formed by laser welding in the first step S05a and the distance of laser welding in the first step S05a vary depending on the laser output value, the material of the sealing plate 13, and the welding speed. For example, when the distance D1 between the starting point P1 and the ending point P2 is approximately 1 mm, the distance D2 from the periphery 13a of the sealing plate 13 to the end of the inner protrusion 30a can be between 0.5 mm and 2 mm.

[0040] If the formal welding process S05 is completed, the following steps are performed: injecting electrolyte into the housing 11, charging the energy storage device 10 and aging it for a specified time, and checking for internal short circuits in the energy storage device 10, thereby manufacturing the energy storage device 10.

[0041] The manufacturing method of the energy storage device 10 according to this embodiment includes a formal welding step S05 in which laser welding is performed on the housing 11 and the sealing plate 13 around the entire circumference of the periphery 13a of the sealing plate 13. The formal welding step S05 includes a first step S05a and a second step S05b. In the formal welding step S05, the starting point P1 of the laser welding is set at a position inside the periphery 13a of the sealing plate 13. In the first step S05a, laser welding is performed from the starting point P1 toward the ending point P2 set at the periphery 13a of the sealing plate 13. In the second step S05b, starting from the ending point P2, laser welding is performed on the housing 11 and the sealing plate 13 around the entire circumference of the periphery 13a of the sealing plate 13.

[0042] According to the manufacturing method of this embodiment, in the first step S05a, since the laser is irradiated at a position closer to the inner side of the periphery 13a of the sealing plate 13, the temperature of the sealing plate 13 easily rises. Therefore, when the welding position reaches the end position of the first step S05a, i.e., the endpoint P2, the sealing plate 13 is fully melted at the endpoint P2. Furthermore, after the first step S05a ends, the second step S05b is performed continuously. Therefore, the second step S05b begins when the temperature of the sealing plate 13 has risen sufficiently. As a result, in the second step S05b, a sufficiently deep weld can be performed throughout the entire periphery 13a of the sealing plate 13. In particular, a sufficiently deep weld can also be performed at the beginning position of the second step S05b, i.e., the endpoint P2. Therefore, the bonding strength between the shell 11 and the sealing plate 13 can be improved.

[0043] According to this embodiment, in the first step S05a, as the welding position in laser welding approaches the periphery 13a of the sealing plate 13 from the starting point P1, the output of the laser used for laser welding increases. Therefore, since a rapid increase in the temperature of the sealing plate 13 can be suppressed, sputtering can be suppressed.

[0044] As described above, according to the inventors' findings, when manufacturing relatively large energy storage devices 10 with a housing 11 width of 30 cm or more, a relatively large gap tends to form between the housing 11 and the sealing plate 13, and the laser tends to deviate significantly towards the housing 11 side compared to the ideal positional relationship. Therefore, when manufacturing relatively large energy storage devices 10, the welding depth at the starting point of laser welding tends to be shallow. On the other hand, relatively large energy storage devices 10 require particularly high bonding strength. Therefore, when manufacturing relatively large energy storage devices 10, even if the laser, housing 11, and sealing plate 13 are in the positional relationship described above, formal welding is still required throughout the entire circumference of the periphery 13a of the sealing plate 13 to achieve a sufficiently deep weld. According to the manufacturing method of this embodiment, welding with a sufficiently deep depth can be performed without omission throughout the entire circumference of the periphery 13a of the sealing plate 13. Therefore, the manufacturing method of this embodiment is particularly effective when manufacturing relatively large batteries.

[0045] The above describes one embodiment of the technology presented herein. However, the above embodiment is only one example, and it can be implemented in other ways.

[0046] Figure 9 This is a schematic diagram illustrating the area near the starting point P1 of laser welding in the formal welding process S05, which involves other methods. Figure 9 In the manner shown, in the first step S05a, laser welding is performed at an angle relative to the periphery 13a of the sealing plate 13. Here, from the viewpoint of ensuring that the temperature of the sealing plate 13 rises sufficiently, the angle θ between the welding trajectory WT in the first step S05a and the periphery 13a of the sealing plate 13 is preferably 30° to 150°, and more preferably 45° to 135°.

[0047] exist Figure 6 In the arrangement shown, the starting point P1 is located to the left of the left electrode terminal 17. However, the position of the starting point P1 is not limited to... Figure 6 The method shown is as follows. For example, the starting point P1 can also be set to the right of the right electrode terminal 17. In this case, in the first step S05a, laser welding can be performed from the starting point P1 toward the right until the periphery 13a of the sealing plate 13. Alternatively, the starting point P1 can also be set between the exhaust valve 14 and the left electrode terminal 17. In this case, in the first step S05a, laser welding can also be performed from the starting point P1 toward the front or rear until the periphery 13a of the sealing plate 13. Similarly, the starting point P1 can also be set between the exhaust valve 14 and the right electrode terminal 17.

[0048] Furthermore, the manufacturing method of the energy storage device 10 may also include steps other than those described above. For example, the manufacturing method of the energy storage device 10 may also include a clamping step of pressing the housing 11 against the sealing plate 13 before the formal welding step S05. This can suppress the occurrence of laser penetration. Laser penetration refers to the phenomenon where a laser beam passes through the gap between the housing 11 and the sealing plate 13 and enters the interior of the housing 11. Similarly, the manufacturing method of the energy storage device 10 may include a clamping step before the temporary welding step S04.

[0049] The above provides various descriptions of the technology disclosed herein. Unless specifically stated otherwise, the embodiments described herein are not intended to limit the invention. Furthermore, the technology disclosed herein is capable of various modifications; unless specific problems arise, the constituent elements and processes mentioned herein can be appropriately omitted or combined. Additionally, this specification includes the disclosures described in the following items.

[0050] Item 1:

[0051] A method for manufacturing an energy storage device, comprising:

[0052] The process of preparing a square shell with an opening;

[0053] The process of preparing to install the sealing plate along the edge of the opening;

[0054] The assembly process of installing the sealing plate onto the opening of the housing; and

[0055] The formal welding process involves laser welding of the shell and the sealing plate around the entire periphery of the sealing plate.

[0056] In the aforementioned formal welding process,

[0057] The starting point for laser welding is set at a position inside the periphery of the aforementioned sealing plate.

[0058] Item 2:

[0059] In the method for manufacturing the energy storage device described in item 1,

[0060] The aforementioned formal welding process includes:

[0061] The first step involves laser welding from the aforementioned starting point toward the aforementioned periphery of the sealing plate; and

[0062] In the second step, after the completion of the first step, laser welding is performed on the shell and the sealing plate along the periphery of the sealing plate, covering the entire periphery of the sealing plate.

[0063] Item 3:

[0064] In the manufacturing method of the energy storage device described in item 1 or 2,

[0065] In the aforementioned formal welding process,

[0066] As the welding position for laser welding approaches the periphery of the sealing plate from the aforementioned starting point, the output of the laser used for laser welding increases.

[0067] Item 4:

[0068] In any of the manufacturing methods of the energy storage device described in items 1 to 3,

[0069] The width of the shell prepared in the process of preparing the shell is 30 cm or more.

[0070] Item 5:

[0071] An energy storage device is obtained by the manufacturing method of the energy storage device described in any one of items 1 to 4, wherein,

[0072] Weld marks are formed around the entire periphery of the aforementioned sealing plate.

[0073] The aforementioned weld mark has an inner protrusion that extends to a position inside the periphery of the aforementioned sealing plate.

Claims

1. A method for manufacturing an energy storage device, characterized in that, Include: The process of preparing a square shell with an opening; The process of preparing a sealing plate to be installed along the edge of the opening; The assembly process of installing the sealing plate into the opening of the housing; as well as The formal welding process involves laser welding of the shell and the sealing plate around the entire periphery of the sealing plate. In the formal welding process, The starting point for laser welding is set at a position inside the periphery of the sealing plate.

2. The method for manufacturing the energy storage device according to claim 1, characterized in that, The formal welding process includes: The first step involves laser welding from the starting point toward the periphery of the sealing plate; and The second step involves laser welding the housing and the sealing plate along the periphery of the sealing plate, covering the entire periphery of the sealing plate.

3. The method for manufacturing the energy storage device according to claim 1, characterized in that, In the formal welding process, As the welding position for laser welding approaches the periphery of the sealing plate from the starting point, the output of the laser used for laser welding increases.

4. The method for manufacturing the energy storage device according to claim 1, characterized in that, The width of the shell prepared in the process of preparing the shell is 30 cm or more.

5. An energy storage device, obtained by the manufacturing method of the energy storage device according to any one of claims 1 to 4. The energy storage device is characterized in that... Weld marks are formed around the entire periphery of the sealing plate. The weld mark has an inner protrusion that extends to a position inside the periphery of the sealing plate.

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