JP2024053770A - Method of manufacturing power storage device, and power storage device - Google Patents

Abstract

To provide a method of manufacturing a power storage device, and the like, capable of facilitating melting of a peripheral edge part of a lid member at laser welding and of suppressing generation of a burned part on a resin member between the lid member and terminal members.SOLUTION: A method of manufacturing a power storage device 1 includes: a closing step S3 of closing an opening 21 of a main body member 20 with a lid member 30 of a lid assembly 7 obtained by integrating terminal members 50 and 60 to the lid member 30 via resin members 70 and 80; and a welding step S4 of laser welding the whole circumference by irradiating the opening 21 of the main body member 20 and a peripheral edge part 31 of the lid member 30 with laser light LB. The lid member 30 has a recessed groove 35 provided at a position between the peripheral edge part 31 and insertion hole peripheral parts 33 and 34 so as to be separated from a molten metal part 18Z to suppress heat transfer from an irradiation portion P of the laser light LB to the insertion hole peripheral parts 33 and 34.SELECTED DRAWING: Figure 7

Description

The present invention relates to a manufacturing method for an electricity storage device such as a battery or capacitor in which a terminal member is fixed to a case via a resin member, and to the electricity storage device.

As an electricity storage device, a rectangular battery is known in which positive and negative terminal members are fixed to a rectangular box-shaped case via a resin member. Specifically, the case is made up of a base-closed rectangular cylindrical main body member having a rectangular annular opening, and a rectangular plate-shaped lid member that is laser welded to the main body member over its entire circumference in a manner that closes the opening. The positive and negative terminal members are inserted into a pair of insertion holes drilled in the lid member, respectively, and extend from inside the case to outside the case. A pair of resin members are joined to the lid member and the terminal members, respectively, while insulating the lid member from the positive and negative terminal members. Examples of related prior art include Patent Documents 1 and 2 (see Figures 1 and 2 of Patent Document 1 and Figures 1 to 4 of Patent Document 2).

JP 2021-086813 A JP 2004-039445 A

In the manufacturing process of such a battery, when the opening of the main body member is sealed with a lid member and the opening of the main body member is laser welded to the entire peripheral edge of the lid member, it is possible to provide a thermal insulating groove near the peripheral edge of the lid member to suppress heat dissipation from the area irradiated with the laser light, make the peripheral edge of the lid member easier to melt, and improve weldability.
However, when a groove is provided near the peripheral portion of the cover member in this manner, a part of the molten metal forming the molten metal portion formed by the irradiation of the laser light may flow into this groove. As a result, the molten metal portion may have a shape different from that in the case where the molten metal portion does not flow into the groove. Specifically, when a part of the molten metal flows into the groove, the molten metal portion may have a shape having a slope that becomes lower toward the groove. It has been found that the high-intensity scattered light of the laser light irradiated onto this slope is irradiated onto the resin member that insulates between the cover member and the terminal member, causing a burnt portion in the resin member.

The present invention was made in consideration of the current situation, and provides a manufacturing method for an electricity storage device that can easily melt the peripheral portion of the lid member when the main body member and the lid member are laser-welded to form a case, and can prevent the occurrence of burnt portions in the resin member that insulates between the lid member and the terminal member due to scattered laser light, and provides an electricity storage device.

(1) One aspect of the present invention for solving the above problem is a method for manufacturing an electric storage device including a case having a bottomed cylindrical main body member having an opening, and a lid member that is laser welded to the main body member over the entire circumference in a manner that closes the opening, a terminal member inserted into an insertion hole that penetrates the lid member in the lid thickness direction, and a resin member that is bonded to the insertion hole periphery of the lid member and the terminal member while insulating between the insertion hole periphery surrounding the insertion hole of the lid member and the terminal member, and the lid member is a part of a lid assembly in which the terminal member is integrated with the lid member via the resin member. The method for manufacturing an electric storage device includes a closing step for closing the opening of the main body member, and a welding step for forming the case by irradiating the lid member with a laser beam from the outside in the lid thickness direction, melting and mixing the opening of the main body member and the peripheral portion of the lid member to form a molten metal portion, and then solidifying the molten and solidified portion by performing laser welding over the entire circumference, and the lid member is provided between the peripheral portion and the insertion hole peripheral portion and at a position separated from the molten metal portion, and has a recessed groove recessed in the lid thickness direction and suppressing heat transfer from the laser beam irradiation portion toward the insertion hole peripheral portion.

In the manufacturing method of the above-mentioned electric storage device, a cover member having the above-mentioned groove between the peripheral portion and the insertion hole peripheral portion is used. As a result, in the welding process, the groove suppresses heat transfer from the laser light irradiation site toward the insertion hole peripheral portion, making it easier to melt the peripheral portion of the cover member and improving weldability. Meanwhile, this groove is separated from the molten metal portion formed by the irradiation of the laser light, and the molten metal does not flow into the groove. This prevents the molten metal from flowing into the groove and causing the molten metal portion to have a shape with a lower slope toward the groove side, and prevents the scattered light of the laser light irradiated to the molten metal portion from being irradiated to the resin member and causing a burnt portion in the resin member.

The "groove" of the cover member may be provided, for example, between the peripheral portion and the surrounding portion of the insertion hole along the entire circumference of the peripheral portion, or along only a part of the peripheral portion. The "groove" may be provided on the outer surface of the cover member or on the inner surface of the cover member.
Examples of "electricity storage devices" include secondary batteries such as lithium ion secondary batteries, capacitors such as lithium ion capacitors, and all-solid-state batteries.

(2) The method for manufacturing an electric storage device according to (1) may further include a method for manufacturing an electric storage device in which the opening of the main body member is a rectangular ring having a pair of long side openings and a pair of short side openings, the peripheral portion of the lid member is a rectangular ring having a pair of long side peripheral portions and a pair of short side peripheral portions, and the closing step includes closing the opening of the main body member with the lid member by placing the pair of long side peripheral portions of the lid member opposite the pair of long side openings of the main body member and the pair of short side peripheral portions of the lid member opposite the pair of short side openings of the main body member, and the grooves are located between the pair of long side peripheral portions and the insertion hole peripheral portion of the lid member, respectively, and include a pair of long side grooves extending along the long side peripheral portions.

In this manufacturing method, the rectangular annular opening of the main body member and the rectangular annular peripheral portion of the cover member are laser welded. In this case, the resin member provided on the cover member is likely to be in close proximity to a part of the long side peripheral portion of the peripheral portion of the cover member, and in the vicinity of the peripheral portion close to the long side peripheral portion of the resin member, molten metal flows into the groove, and the molten metal portion has a shape with a slope that is lower toward the groove side. As a result, the scattered light of the laser light irradiated to the molten metal portion is irradiated to the resin member (periphery adjacent portion), and a burnt portion is likely to occur in this portion. This is because the distance that the scattered light of the laser light reaches the resin member (periphery adjacent portion) is short.
In contrast, in the above-described method for manufacturing an electricity storage device, the groove provided in the cover member includes a long-side groove located between the long-side peripheral portion and the insertion hole peripheral portion and extending along the long-side peripheral portion, which makes it possible to suppress the occurrence of scorching in the resin member, particularly in the peripheral portion close to the long-side peripheral portion, where scorching is likely to occur.

(3) The method for manufacturing the electric storage device according to (1) or (2) may further include an outer groove provided on the outer surface of the lid member, the outer groove having a peripheral portion side inner surface located on the peripheral portion side and a hole peripheral portion side inner surface located on the insertion hole peripheral portion side, and the peripheral portion side inner surface of the outer groove has a shape that is farther away from the peripheral portion toward the outer surface side in the thickness direction of the lid.

In the manufacturing method of the electric storage device described above, an outer groove is provided on the outer surface of the lid member, in which the inner surface on the peripheral portion is farther from the peripheral portion toward the outer surface in the thickness direction of the lid. This lengthens the distance from the molten metal portion to the opening of the outer groove, preventing the molten metal from flowing into the outer groove, while allowing the internal space of the outer groove to be located closer to the site irradiated with the laser light (closer to the peripheral portion) than when an outer groove is provided in which the inner surface on the peripheral portion extends in the thickness direction of the lid. This makes it possible to more effectively suppress the transfer of heat from the site irradiated with the laser light toward the area surrounding the insertion hole, improving weldability.

(4) In the method for manufacturing an electric storage device according to (1) or (2), the groove may further include an inner groove provided on the inner surface of the lid member.

In the manufacturing method of the electric storage device described above, an inner groove is provided on the inside surface of the cover member. There is no risk of molten metal flowing into the inner groove, as there is in the outer groove. Therefore, the inner groove can be provided closer to the laser light irradiation site (closer to the periphery) than when an outer groove is provided, so that heat transfer from the laser light irradiation site toward the periphery of the insertion hole can be more effectively suppressed, improving weldability.

(5) Another aspect is an electric storage device including a case having a bottomed cylindrical main body member having an opening, and a lid member laser-welded to the main body member over the entire circumference in a form that closes the opening, a terminal member inserted into an insertion hole penetrating the lid member in the lid thickness direction, and a resin member bonded to the insertion hole surrounding portion of the lid member and the terminal member while insulating between the insertion hole surrounding portion surrounding the insertion hole of the lid member and the terminal member, the lid member being provided between the peripheral portion of the lid member and the insertion hole surrounding portion and at a position separated from the molten metal portion formed by the irradiation of the laser light, recessed in the lid thickness direction, and having a groove that suppresses heat transfer from the irradiated portion of the laser light toward the insertion hole surrounding portion, and the resin member being an electric storage device in which the occurrence of a burnt portion is suppressed by the groove of the lid member.

In the above-mentioned electricity storage device, the occurrence of burnt areas in the resin member is suppressed, so the original appearance of the resin member can be maintained and the decrease in insulation resistance between the cover member and the terminal member due to the burnt areas can be suppressed.

(6) The electric storage device according to (5) may further be such that the opening of the main body member is a rectangular ring having a pair of long side openings and a pair of short side openings, the peripheral portion of the lid member is a rectangular ring having a pair of long side peripheral portions and a pair of short side peripheral portions, the grooves are located between the pair of long side peripheral portions and the insertion hole peripheral portion of the lid member, respectively, and include a pair of long side grooves extending along the long side peripheral portions, and the resin member is an electric storage device in which the generation of burnt portions is suppressed in peripheral vicinity portions of the resin member that are close to the long side peripheral portions due to the long side grooves of the lid member.

In the above-mentioned energy storage device, the occurrence of burnt areas is suppressed in the peripheral area of the resin member close to the long side peripheral edge of the lid member, where burnt areas are particularly likely to occur. This allows the original appearance of the resin member to be maintained even in this peripheral area, and also suppresses a decrease in insulation resistance.

(7) The electric storage device according to (5) or (6) may further include an outer groove provided on the outer surface of the lid member, the outer groove having a peripheral portion side inner surface located on the peripheral portion side and a hole peripheral portion side inner surface located on the insertion hole peripheral portion side, and the peripheral portion side inner surface of the outer groove has a shape that is farther away from the peripheral portion toward the outer surface side in the thickness direction of the lid.

In the above-mentioned energy storage device, the grooves, including the outer grooves, prevent the occurrence of burnt areas in the resin member, so that the original appearance of the resin member can be maintained and the insulation resistance between the cover member and the terminal member can be prevented from decreasing due to the burnt areas.

(8) In the electric storage device described in (5) or (6), the groove may further include an inner groove provided on the inner surface of the lid member.

In the above-mentioned energy storage device, the grooves, including the inner grooves, prevent the occurrence of burnt areas in the resin member, so that the original appearance of the resin member can be maintained and the insulation resistance between the cover member and the terminal member can be prevented from decreasing due to the burnt areas.

FIG. 1 is a perspective view of a battery according to a first embodiment. 1 is a cross-sectional view of a battery according to a first embodiment taken along a battery height direction and a battery width direction. 1A is a partially enlarged cross-sectional view of the opening of the main body member and the peripheral portion of the cover member of the battery of embodiment 1, where (a) is a partially enlarged cross-sectional view along the battery height direction and battery width direction, and (b) is a partially enlarged cross-sectional view along the battery height direction and battery thickness direction. 2 is a flowchart of a method for manufacturing a battery according to the first embodiment. 4 is an explanatory diagram showing a lid assembly formed in a lid assembly forming step in the manufacturing method of the battery according to the first embodiment. FIG. 4 is an explanatory diagram showing the state in which the opening of the main body member is closed with the lid member constituting the lid assembly in the closing step in the manufacturing method of the battery according to the first embodiment. FIG. 1A is an explanatory diagram showing the state in which the opening (long side opening) of the main body member and the peripheral portion (long side peripheral portion) of the cover member are laser welded together in a welding process in the manufacturing method for a battery of embodiment 1; FIG. 1B is an explanatory diagram showing the state in which the irradiation of the laser light is started; and FIG. 1B is an explanatory diagram showing the state in which a molten metal portion is formed by the irradiation of the laser light. 5A and 5B are enlarged partial cross-sectional views corresponding to FIG. 3 in the vicinity of the opening of the main body member and the peripheral portion of the cover member of the battery of embodiment 3, where (a) is a partially enlarged cross-sectional view along the battery height direction and the battery width direction, and (b) is a partially enlarged cross-sectional view along the battery height direction and the battery thickness direction. 10A is an explanatory diagram showing the state before the first press is performed to form a groove in the lid member in the lid forming process of the battery manufacturing method of embodiment 3, and FIG. 10B is an explanatory diagram showing the state after the first press is performed. 10A is an explanatory diagram showing the state before the second press is performed on the lid member in the lid forming process of the battery manufacturing method of embodiment 3, and FIG. 10B is an explanatory diagram showing the state after the second press is performed. 10A is an explanatory diagram showing the state before forging is performed on the lid member in the lid forming process of the battery manufacturing method of embodiment 3, and FIG. 10B is an explanatory diagram showing the state after forging to form a groove. 8A and 8B are explanatory diagrams corresponding to FIG. 7 and relating to a method for manufacturing a battery according to a comparative embodiment, in which (a) is an explanatory diagram showing the state in which irradiation of laser light has commenced, and (b) is an explanatory diagram showing the state in which a molten metal portion has been formed by irradiation of laser light.

(Embodiment 1)
A first embodiment of the present invention will be described below with reference to the drawings. Fig. 1 shows a perspective view of a battery (electricity storage device) 1 according to this embodiment 1, Fig. 2 shows a cross-sectional view of the entire battery 1, and Fig. 3 shows an enlarged cross-sectional view of a portion of the battery 1 near an opening 21 of a main body member 20 and a peripheral portion 31 of a lid member 30. In the following description, the battery height direction AH, battery width direction BH, and battery thickness direction CH of the battery 1 are defined as the directions shown in Figs. 1 to 3. The battery 1 is a rectangular (rectangular) sealed lithium ion secondary battery that is mounted on vehicles such as hybrid cars, plug-in hybrid cars, and electric cars.

The battery 1 is composed of a case 10, an electrode body 40 housed in the case 10, and positive and negative terminal members 50, 60 supported on the case upper part 11 of the case 10 via resin members 70, 80. Inside the case 10, the electrode body 40 is covered by a bag-shaped insulating holder 5 made of insulating film and opening to the upper side AH1 in the battery height direction AH. Also housed within the case 10 is an electrolyte 3, a part of which is impregnated into the electrode body 40 and the remainder is stored on the case bottom 12 of the case 10.

The case 10 is a rectangular box made of metal (aluminum in this embodiment 1) and has a rectangular case upper part 11 located on the upper side AH1 in the battery height direction AH, a rectangular case bottom part 12 facing it and located on the lower side AH2 in the battery height direction AH, and four rectangular case sides (a pair of case long sides 13, 14 and a pair of case short sides 15, 16) connecting the two.

The case 10 is composed of a main body member 20 and a lid member 30. The main body member 20 is a rectangular cylindrical member with a bottom having a rectangular ring-shaped opening 21 with a pair of long side openings 21b and a pair of short side openings 21c on the upper side AH1 of the battery height direction AH, and forms the case bottom 12, case long side parts 13, 14, and case short side parts 15, 16 of the case 10. On the other hand, the lid member 30 is a rectangular plate having an outer side 30m and an inner side 30n, and forms the case upper part 11 of the case 10. The lid member 30 is laser welded to the main body member 20 around its entire circumference in a form that closes the opening 21 of the main body member 20, and a melted and solidified part 18 is formed between the lid member 30 and the main body member 20. Specifically, a pair of long side openings 21b of the rectangular annular opening 21 of the main body member 20 is welded to a pair of long side peripheral portions 31b of the rectangular annular peripheral portion 31 of the cover member 30 to form the melted solidified portion 18 (see FIG. 3(b)). Also, a pair of short side openings 21c of the opening 21 of the main body member 20 is welded to a pair of short side peripheral portions 31c of the peripheral portion 31 of the cover member 30 to form the melted solidified portion 18 (see FIG. 3(a)).

The cover member 30 is provided with a safety valve 38 that breaks and opens when the internal pressure of the case 10 exceeds a valve opening pressure. The cover member 30 is also formed with a liquid injection hole 30k that communicates between the inside and outside of the case 10, and is airtightly sealed with a disk-shaped sealing member 39 made of aluminum.
The lid member 30 has rectangular insertion holes 33h, 34h near an end of one side BH1 in the battery width direction BH and near an end of the other side BH2, respectively, penetrating in the lid thickness direction DH. A positive electrode terminal member 50 made of aluminum is inserted into one of the insertion holes 33h and is fixed to the lid member 30 in a state insulated from the lid member 30 via a resin member 70. A negative electrode terminal member 60 made of copper is inserted into the other insertion hole 34h and is fixed to the lid member 30 in a state insulated from the lid member 30 via a resin member 80.

These terminal members 50, 60 each have a rectangular plate-shaped external terminal portion 51, 61 arranged on the cover member 30, and an internal terminal portion 52, 62 arranged mainly inside the case 10 and connected to the external terminal portion 51, 61 via the insertion holes 33h, 34h of the cover member 30. The positive internal terminal portion 52 is joined to the positive electrode tab 40a of the electrode body 40 inside the case 10 and is electrically connected. On the other hand, the negative internal terminal portion 62 is joined to the negative electrode tab 40b of the electrode body 40 inside the case 10 and is electrically connected.

The positive electrode resin member 70 surrounds the insertion hole 33h of the cover member 30, and is bonded to the insertion hole surrounding portion 33 of the cover member 30 and the terminal member 50 while insulating the rectangular annular insertion hole surrounding portion 33 having a pair of long side surrounding portions 33e and a pair of short side surrounding portions 33f from the terminal member 50. Similarly, the negative electrode resin member 80 surrounds the insertion hole 34h of the cover member 30, and is bonded to the insertion hole surrounding portion 34 of the cover member 30 and the terminal member 60 while insulating the rectangular annular insertion hole surrounding portion 34 having a pair of long side surrounding portions 34e and a pair of short side surrounding portions 34f from the terminal member 60.

These resin members 70, 80 are made of polyphenylene sulfide (PPS) and have rectangular plate-shaped external insulating parts 71, 81 arranged on the lid member 30, and internal insulating parts 72, 82 arranged inside the case 10 and in the insertion holes 33h, 34h of the lid member 30 and connected to the external insulating parts 71, 81. Of these, the external insulating parts 71, 81 insulate between the external terminal parts 51, 61 of the terminal members 50, 60 and the insertion hole surrounding parts 33, 34 of the lid member 30. On the other hand, the internal insulating parts 72, 82 insulate between the internal terminal parts 52, 62 of the terminal members 50, 60 and the insertion hole surrounding parts 33, 34 of the lid member 30.

In addition, on the outer surface 30m of the lid member 30, between the peripheral portion 31 and the insertion hole surrounding portions 33, 34, and at a position away from the molten metal portion 18Z formed by irradiation with laser light LB (see Figures 7(a) and (b)) described below, a groove (outer groove) 35 is provided along the entire circumference of the peripheral portion 31, recessed in the lid thickness direction DH toward the lower side AH2 in the battery height direction AH.

That is, the grooves 35 of this embodiment 1 are located between a pair of long side peripheral portions 31b of the peripheral portion 31 of the cover member 30 and a pair of long side peripheral portions 33e, 34e of the insertion hole peripheral portions 33, 34, respectively, and include long side grooves 36 (see Figures 1 and 3(b)) that extend along the long side peripheral portions 31b, and short side grooves 37 (see Figures 1 and 3(a)) that are located between a pair of short side peripheral portions 31c of the peripheral portion 31 of the cover member 30 and a pair of short side peripheral portions 33f of the insertion hole peripheral portions 33, 34, respectively, and extend along the short side peripheral portions 31c.

The groove 35 in the first embodiment has a U-shaped cross section. That is, the groove 35 has a peripheral portion-side inner surface 35a located on the peripheral portion 31 side of the lid member 30 (left side in Figs. 3(a) and 3(b)) and extending in the lid thickness direction DH, a hole-periphery portion-side inner surface 35b located on the insertion hole peripheral portions 33 and 34 side of the lid member 30 (left side in Figs. 3(a) and 3(b)) and extending in the lid thickness direction DH parallel to the peripheral portion-side inner surface 35a, and a bottom surface 35c perpendicular to the peripheral portion-side inner surface 35a and the hole-periphery portion-side inner surface 35b, respectively, and parallel to the outer surface 30m and the inner surface 30n of the lid member 30.
As described below, this type of groove 35 suppresses heat transfer from the irradiation site P of the laser light LB toward the insertion hole surrounding areas 33, 34, and prevents the occurrence of burnt areas BP (see Figure 12 (b)) in the resin members 70, 80.

The electrode body 40 is a flat rectangular parallelepiped, and is a laminated electrode body in which multiple positive electrode plates 41 and multiple negative electrode plates 42, each of which has a rectangular shape extending in the battery height direction AH and the battery width direction BH, are alternately stacked in the battery thickness direction CH via separators 43 made of a porous resin film. Each positive electrode plate 41 has a positive electrode current collector 41r extending to the upper side AH1, and the positive electrode current collectors 41r overlap each other in the thickness direction to form the positive electrode tab 40a described above. This positive electrode tab 40a is connected to the internal terminal portion 52 of the positive electrode terminal member 50 as described above. Each negative electrode plate 42 has a negative electrode current collector 42r extending to the upper side AH1, and the negative electrode current collectors 42r overlap each other in the thickness direction to form the negative electrode tab 40b described above. This negative electrode tab 40b is connected to the internal terminal portion 62 of the negative electrode terminal member 60 as described above.

In the battery 1 of this embodiment 1, the groove 35 prevents the occurrence of burnt parts BP in the resin members 70, 80, so that the original appearance of the resin members 70, 80 can be maintained, and the insulation resistance between the cover member 30 and the terminal members 50, 60 can be prevented from decreasing via the burnt parts BP. In particular, in this embodiment 1, the long side groove 36 of the groove 35 prevents the occurrence of burnt parts BP even in the peripheral vicinity parts 70e, 80e of the resin members 70, 80 that are close to the long side peripheral part 31b of the cover member 30, where the burnt parts BP are likely to occur. Therefore, the original appearance of the resin members 70, 80 can be maintained even in the peripheral vicinity parts 70e, 80e, and the decrease in insulation resistance can be prevented.

Next, a method for manufacturing the battery 1 will be described (see Figures 4 to 7). First, in the "lid formation step S1" (see Figure 4), the lid member 30 is formed. That is, an aluminum plate is prepared and punched out into a rectangular shape using a press, and the liquid injection hole 30k, the insertion holes 33h, 34h, the recessed groove 35, and the safety valve 38 are provided to obtain the lid member 30.

Next, in the "lid assembly formation process S2" (see FIG. 4), the lid assembly 7 is formed (see FIG. 5). That is, the terminal members 50, 60 are further prepared, and the resin members 70, 80 are insert molded to integrate the terminal members 50, 60 with the lid member 30 via the resin members 70, 80. Specifically, the positive terminal member 50 is made of an aluminum plate, and the negative terminal member 60 is made of a copper plate, each of which is press processed. Then, with the terminal members 50, 60 inserted into the insertion holes 33h, 34h of the lid member 30, the resin members 70, 80 are insert molded to integrate the terminal members 50, 60 with the lid member 30 via the resin members 70, 80.

Next, an electrode body 40 is prepared by stacking a positive electrode plate 41, a negative electrode plate 42, and a separator 43, and the internal terminal portions 52, 62 of the terminal members 50, 60 integrated with the above-mentioned lid member 30 are connected by welding to the positive electrode tab 40a and the negative electrode tab 40b of the electrode body 40, respectively. After that, the electrode body 40 is wrapped in a bag-shaped insulating holder 5. Thus, a lid assembly 7 consisting of the lid member 30, the terminal members 50, 60, the resin members 70, 80, the electrode body 40, and the insulating holder 5 is formed.

Next, in the "closing step S3" (see FIG. 4), the main body member 20 is prepared, the electrode body 40 covered with the insulating holder 5 of the lid assembly 7 is inserted into the main body member 20, and the opening 21 of the main body member 20 is closed with the lid member 30 (see FIG. 6). Specifically, a pair of long side peripheral portions 31b of the peripheral portion 31 of the lid member 30 are opposed to a pair of long side openings 21b of the opening 21 of the main body member 20, and a pair of short side peripheral portions 31c of the peripheral portion 31 of the lid member 30 are opposed to a pair of short side openings 21c of the opening 21 of the main body member 20, thereby closing the opening 21 of the main body member 20 with the lid member 30.

Next, in the "welding process S4" (see Figure 4), laser light LB is irradiated to the opening 21 of the main body member 20 and the peripheral portion 31 of the cover member 30 from the outside DH1 in the cover thickness direction DH of the cover member 30 (the upper side AH1 in the battery height direction AH), and the opening 21 and the peripheral portion 31 are melted and mixed to form a molten metal portion 18Z, which is then solidified to form a molten and solidified portion 18. Laser welding is then performed around the entire circumference to form the case 10 (see Figures 7 (a) and (b)).
In this case, a thermal insulating groove 35 is provided between the peripheral portion 31 of the cover member 30 and the insertion hole surrounding portions 33, 34, so that the groove 35 suppresses heat transfer from the irradiation site P of the laser light LB toward the insertion hole surrounding portions 33, 34, making the peripheral portion 31 of the cover member 30 easier to melt and improving weldability.

12(a) and (b) show comparative examples. When the distance between the peripheral portion 31 and the groove 935 is short, the molten metal ML forming the molten metal portion 918Z formed by the irradiation of the laser light LB flows into the groove 935. Then, the shape of the molten metal portion 918Z has a lower slope 918Zm toward the groove 935 (right side in FIG. 12). Therefore, the scattered light LC of the laser light LB irradiated to the slope 918Zm is irradiated to the resin members 70 and 80, and the burnt portion BP is likely to occur in the resin members 70 and 80. In particular, the resin members 70 and 80 provided on the cover member 30 are close to a part of the long side peripheral portion 31b of the peripheral portion 31 of the cover member 30. For this reason, the peripheral adjacent portions 70e, 80e of the resin members 70, 80 that face and are adjacent to the long side peripheral portion 31b of the peripheral portion 31 of the cover member 30 are irradiated with high-intensity scattered light LC, and are therefore particularly susceptible to the occurrence of burnt portions BP.

In contrast, in this embodiment 1 (see Figs. 7(a) and 7(b)), the long side grooves 36 and the short side grooves 37 of the grooves 35 are both formed at positions sufficiently separated from the peripheral portion 31, so that they are separated from the molten metal portion 18Z formed by the irradiation of the laser light LB, and the molten metal ML does not flow into the grooves 35. This prevents the molten metal ML from flowing into the grooves 35 and the shape of the molten metal portion 18Z from having a slope that is lower (lower in Fig. 7) toward the groove 35, and prevents the scattered light LC of the laser light LB irradiated to the molten metal portion 18Z from being irradiated to the resin members 70 and 80, and the occurrence of burnt portions BP in the resin members 70 and 80 (even in the peripheral vicinity portions 70e and 80e) can be prevented.

Next, in a "pouring and sealing step S5", the electrolyte 3 is poured into the case 10 through the filling hole 30k, and the electrolyte 3 is impregnated into the electrode body 40. Thereafter, the filling hole 30k is covered from the outside with a sealing member 39, and the sealing member 39 is welded to the lid member 30 around its entire periphery to hermetically seal the gap between the sealing member 39 and the lid member 30.
Next, in the "initial charging and aging step S6", a charging device (not shown) is connected to the battery 1 to perform an initial charge on the battery 1. After that, the initially charged battery 1 is left to stand for a predetermined time to age the battery 1. In this way, the battery 1 is completed.

In the manufacturing method of the battery 1 of the present embodiment 1, a cover member 30 having a groove 35 between the peripheral portion 31 and the insertion hole surrounding portions 33, 34 is used. As a result, in the welding step S4, the groove 35 suppresses the heat transfer from the irradiation portion P of the laser light LB toward the insertion hole surrounding portions 33, 34, making it easier to melt the peripheral portion 31 of the cover member 30 and improving the weldability. On the other hand, the groove 35 is separated from the molten metal portion 18Z, and the molten metal ML does not flow into the groove 35. Therefore, the molten metal ML is prevented from flowing into the groove 35 and the molten metal portion 18Z is prevented from having a shape having a lower slope toward the groove 35 side, and the scattered light LC of the laser light LB irradiated to the molten metal portion 18Z is irradiated to the resin members 70, 80, and the scorched portion BP is prevented from being generated in the resin members 70, 80.
Furthermore, in the present embodiment 1, the groove 35 includes a long side groove 36 that is located between the long side peripheral portion 31b and the insertion hole peripheral portions 33, 34 and extends along the long side peripheral portion 31b. Therefore, it is possible to suppress the occurrence of the burnt portion BP in the peripheral vicinity portions 70e, 80e of the resin members 70, 80 that are close to the long side peripheral portion 31b and where the burnt portion BP is particularly likely to occur.

(Embodiment 2)
Next, a second embodiment will be described. Note that the description of the same parts as those of the first embodiment will be omitted or simplified. In the battery 1 of the first embodiment, a groove (outer groove) 35 is provided on the outer side surface 30m of the cover member 30. In contrast, in the battery 100 of the second embodiment, a groove (inner groove) 135 is provided on the inner side surface 30n of the cover member 30 instead of the groove (outer groove) 35, as shown by the dashed lines in Figs. 3 and 7.

That is, on the inner surface 30n of the lid member 30, between the peripheral portion 31 and the insertion hole surrounding portions 33, 34, and at a position away from the molten metal portion 18Z formed by the irradiation of the laser light LB, a groove (inner groove) 135 recessed toward the upper side AH1 in the battery height direction AH in the lid thickness direction DH is provided along the entire circumference of the peripheral portion 31. This groove 135 has a long side groove 136 (see FIG. 3(b)) that extends along the long side peripheral portion 31b of the peripheral portion 31, and a short side groove 137 (see FIG. 3(a)) that extends along the short side peripheral portion 31c of the peripheral portion 31, similar to the groove 35 of the first embodiment.

The groove 135 of this embodiment 2 also has a U-shaped cross section. That is, the groove 135 has a peripheral portion side inner surface 135a located on the peripheral portion 31 side of the lid member 30 and extending in the lid thickness direction DH, a hole peripheral portion side inner surface 135b located on the insertion hole peripheral portions 33, 34 side of the lid member 30 and extending in the lid thickness direction DH parallel to the peripheral portion side inner surface 135a, and a bottom surface 135c perpendicular to the peripheral portion side inner surface 135a and the hole peripheral portion side inner surface 135b, respectively, and parallel to the outer surface 30m and inner surface 30n of the lid member 30.

In the battery 100 of the second embodiment, in the welding step S4, the groove 135 suppresses heat transfer from the irradiation site P of the laser light LB toward the insertion hole surrounding parts 33, 34, making it easier to melt the peripheral part 31 of the cover member 30 and improving weldability. Meanwhile, the groove 135 is separated from the molten metal part 18Z, and the molten metal ML does not flow into the groove 135, so that it is possible to prevent the generation of scorched parts BP in the resin members 70, 80 due to the scattered light LC of the laser light LB, as in the first embodiment.
In particular, in the second embodiment, the groove 135 is an inner groove provided on the inner side surface 30n of the cover member 30, so there is no risk of the molten metal ML flowing in as in the outer groove. Therefore, the groove 135 can be provided at a position closer to the irradiation site P of the laser light LB (a position closer to the peripheral portion 31) than in the case of providing an outer groove, so that the heat transfer from the irradiation site P of the laser light LB can be more effectively suppressed and the weldability can be improved. Other parts similar to those of the first embodiment provide the same functions and effects as those of the first embodiment.

(Embodiment 3)
Next, the third embodiment will be described. The description of the same parts as those of the first or second embodiment will be omitted or simplified. In the battery 1 of the first embodiment, the groove (outer groove) 35 provided on the outer surface 30m of the cover member 30 has a U-shaped cross section in which the peripheral portion side inner surface 35a and the hole surrounding portion side inner surface 35b extend parallel to each other in the cover thickness direction DH (see Figs. 3 and 7). In contrast, in the battery 200 of the third embodiment, the groove (outer groove) 235 provided on the outer surface 30m of the cover member 30 has a different shape from the groove 35 of the first embodiment (see Figs. 8(a) and (b)).

That is, the groove 235 of this embodiment 3, like the groove 35 of embodiment 1, is provided on the outer surface 30m of the cover member 30 between the peripheral edge 31 and the insertion hole surrounding parts 33, 34, and at a position separated from the molten metal part 18Z, around the entire circumference of the peripheral edge 31. The groove 235 also has a long side groove 236 (see FIG. 8(b)) that extends along the long side peripheral edge 31b of the peripheral edge 31, and a short side groove 237 (see FIG. 8(a)) that extends along the short side peripheral edge 31c of the peripheral edge 31.

However, the groove 235 of this embodiment 3 has a cross-sectional shape different from that of the groove 35 of embodiment 1. Specifically, the groove 235 has a peripheral portion side inner surface 235a located on the peripheral portion 31 side of the cover member 30 (left side in Figs. 8(a) and (b)), a hole surrounding portion side inner surface 235b located on the insertion hole surrounding portion 33, 34 side of the cover member 30 (right side in Figs. 8(a) and (b)), and a bottom surface 235c connecting them. Of these, the hole surrounding portion side inner surface 235b extends in the cover thickness direction DH, similar to the hole surrounding portion side inner surface 35b of the groove 35 of embodiment 1. The bottom surface 235c extends parallel to the outer surface 30m and inner surface 30n of the cover member 30, similar to the bottom surface 35c of the groove 35 of embodiment 1. On the other hand, the inner surface 235a on the peripheral edge side is a flat surface that is farther away from the peripheral edge 31 (to the right in Figures 8(a) and (b)) toward the outer surface 30m in the lid thickness direction DH (upper side AH1 in the battery height direction AH).

The groove 235 is formed by the following method (see Figures 9 to 11). That is, in the lid forming process S1, first, a lid member 30Z without a groove 235 is formed. Specifically, an aluminum plate is prepared, and it is punched into a rectangular shape by a press, and a liquid injection hole 30k, insertion holes 33h, 34h, and a safety valve 38 are provided, thereby obtaining a lid member 30Z without a groove 235 (see Figure 9 (a)).

Next, a first press is performed on the lid member 30Z before the groove is formed to form the groove 235. Specifically, as shown in FIG. 9(a), a first mold KA is placed on the outer surface 30m of the lid member 30Z, and a second mold KB is placed on the inner surface 30n of the lid member 30Z, and the lid member 30Z is sandwiched between the first mold KA and the second mold KB in the lid thickness direction DH. Then, as shown in FIG. 9(b), a third mold KC is moved downward in FIG. 9(b) toward the lid member 30Z and the second mold KB in the lid thickness direction DH, and the third mold KC and the second mold KB press and thin the peripheral vicinity portion 32Z of the lid member 30Z, including the peripheral portion 31Z.

Then, a second press is performed on the peripheral portion 32Z of the lid member 30Z. Specifically, as shown in FIG. 10(a), a fourth mold KD is placed on the outer surface 30m of the lid member 30Z, and a fifth mold KE is placed on the inner surface 30n of the lid member 30Z, and the lid member 30Z is sandwiched between the fourth mold KD and the fifth mold KE in the lid thickness direction DH. Then, as shown in FIG. 10(b), a sixth mold KF is moved downward in the lid thickness direction DH toward the lid member 30Z and the fifth mold KE, and the peripheral portion 32Z of the lid member 30Z is pressed with the sixth mold KF and the fourth mold KD to provide a recess 32Zv in the peripheral portion 32Z. This recess 32Zv has a generally V-shaped cross section and has a peripheral portion side inner surface 32Zva that forms a flat surface that approaches the peripheral portion 31Z toward the outer surface 30m in the lid thickness direction DH, and a hole surrounding portion side inner surface 32Zvb that extends in the lid thickness direction DH.

Then, forging is performed on the peripheral vicinity 32Z of the lid member 30Z. Specifically, as shown in FIG. 11(a), the seventh die KG is placed on the outer surface 30m of the lid member 30Z, and the eighth die KH is placed on the inner surface 30n of the lid member 30Z, and the lid member 30Z is sandwiched between the seventh die KG and the eighth die KH in the lid thickness direction DH. Then, as shown in FIG. 11(b), the ninth die KI is moved upward in the lid thickness direction DH toward the lid member 30Z and the seventh die KG, and the peripheral vicinity 32Z of the lid member 30Z is struck to plastically deform the peripheral vicinity 32Z. This forms the lid member 30 having the groove 235 in a form in which the peripheral portion side inner surface 235a is farther away from the peripheral portion 31 as it approaches the outer surface 30m in the lid thickness direction DH. Thereafter, the lid assembly forming process S2 and subsequent processes are performed in the same manner as in the first embodiment to manufacture the battery 200.

In the battery 200 of this embodiment 3, in the welding process S4, the groove 235 suppresses the heat transfer from the irradiation site P of the laser light LB toward the insertion hole surrounding parts 33, 34, making it easier to melt the peripheral part 31 of the cover member 30 and improving weldability. On the other hand, this groove 235 is separated from the molten metal part 18Z, and the molten metal ML does not flow into the groove 235, so as in embodiment 1, it is possible to prevent the scattered light LC of the laser light LB from causing scorched parts BP in the resin members 70, 80.

In particular, in this embodiment 3, the inner surface 235a on the peripheral side of the groove 235 is configured to be farther away from the peripheral portion 31 of the lid member 30 toward the outer surface 30m in the lid thickness direction DH, so that the distance from the molten metal portion 18Z to the opening of the groove 235 is increased, preventing the molten metal ML from flowing into the groove 235, while providing the internal space of the groove 235 at a position closer to the irradiation site P of the laser light LB (closer to the peripheral portion 31) than the groove 35 in embodiment 1. This makes it possible to more effectively suppress the transfer of heat from the irradiation site P of the laser light LB toward the insertion hole surrounding portions 33, 34, improving weldability.

In the above, the present invention has been described in accordance with embodiments 1 to 3. However, the present invention is not limited to embodiments 1 to 3, and it goes without saying that the present invention can be modified and applied as appropriate without departing from the spirit of the present invention.
For example, in the first to third embodiments, the laminated electrode body 40 is exemplified as the electrode body housed in the case 10, but the electrode body may be a flat wound electrode body. Also, a plurality of electrode bodies may be housed in the case.

1,100,200 Battery (electricity storage device)
7 Lid assembly 10 Case 18 Melted and solidified portion 18Z Molten metal portion 20 Body member 21 Opening 21b Long side opening 21c Short side opening 30 Lid member 31 Peripheral portion 31b Long side peripheral portion 31c Short side peripheral portion 33, 34 Insertion hole peripheral portion 33h, 34h Insertion hole 33e, 34e Long side peripheral portion 33f, 34f Short side peripheral portion 35, 235 Groove (outer groove)
135 Groove (inner groove)
35a, 135a, 235a Inner surface on peripheral portion side 35b, 135b, 235b Inner surface on hole surrounding portion side 35c, 135c, 235c Bottom surface 36, 136, 236 Long side groove 37, 137, 237 Short side groove 40 Electrode body 50, 60 Terminal member 70, 80 Resin member 70e, 80e Periphery adjacent portion DH (of the resin member adjacent to the long side peripheral portion of the lid member) Lid thickness direction DH1 Outside DH2 (in the lid thickness direction) Inside LB (in the lid thickness direction) Laser light LC Scattered light P Irradiation portion ML Molten metal BP Burnt portion S1 Lid forming process S2 Lid assembly forming process S3 Closing process S4 Welding process S5 Liquid injection and sealing process S6 Initial charging and aging process

Claims (8)

a case including a bottomed tubular main body member having an opening, and a cover member that is laser welded to the main body member over an entire periphery thereof in a manner that closes the opening;
a terminal member inserted into an insertion hole passing through the cover member in a thickness direction of the cover;
a resin member joined to the insertion hole surrounding portion of the lid member and the terminal member while insulating the insertion hole surrounding portion of the lid member and the terminal member,
a closing step of closing the opening of the main body member with the lid member of a lid assembly formed by integrating the terminal member with the lid member via the resin member;
a welding process for forming the case by irradiating the lid member with a laser beam from the outside in the lid thickness direction, melting and mixing the opening of the main body member and the peripheral edge of the lid member to form a molten metal portion, and then solidifying the molten metal portion to form a molten solidified portion over the entire periphery,
The cover member is
A manufacturing method for an electricity storage device having a groove provided between the peripheral portion and the insertion hole surrounding portion and at a position away from the molten metal portion, recessed in the thickness direction of the lid, and suppressing heat transfer from the laser light irradiated portion toward the insertion hole surrounding portion. A method for producing the electricity storage device according to claim 1, comprising the steps of:
The opening in the body member is
A rectangular ring having a pair of long side openings and a pair of short side openings,
The peripheral portion of the cover member is
A rectangular ring shape having a pair of long side peripheral edges and a pair of short side peripheral edges,
The blocking step includes:
the pair of long side peripheral portions of the cover member are opposed to the pair of long side openings of the main body member, and the pair of short side peripheral portions of the cover member are opposed to the pair of short side openings of the main body member, respectively, to close the openings of the main body member with the cover member;
The groove is
A method for manufacturing an electricity storage device, comprising: the cover member including a pair of long side grooves located between the pair of long side peripheral portions and the insertion hole peripheral portion, respectively, and extending along the long side peripheral portions. A method for producing the electricity storage device according to claim 1 or 2, comprising the steps of:
The groove is
an outer groove provided on an outer surface of the cover member, the outer groove having a peripheral portion-side inner surface located on the peripheral portion side and a hole peripheral portion-side inner surface located on the insertion hole peripheral portion side;
The inner surface of the outer groove on the peripheral edge side is
A method for manufacturing an electricity storage device having a configuration in which the outer surface side in a thickness direction of the lid becomes farther from the peripheral portion. A method for producing the electricity storage device according to claim 1 or 2, comprising the steps of:
The groove is
The method for manufacturing an electricity storage device includes an inner groove provided on an inner surface of the cover member. a case including a bottomed tubular main body member having an opening, and a cover member that is laser welded to the main body member over an entire periphery thereof in a manner that closes the opening;
a terminal member inserted into an insertion hole passing through the cover member in a thickness direction of the cover;
a resin member that insulates between an insertion hole surrounding portion surrounding the insertion hole of the lid member and the terminal member and is joined to the insertion hole surrounding portion of the lid member and the terminal member,
The cover member is
a recessed groove provided between the peripheral edge of the lid member and the peripheral portion of the insertion hole and at a position separated from the molten metal portion formed by the irradiation of the laser light, the recessed groove being recessed in the thickness direction of the lid and suppressing heat transfer from the irradiated portion of the laser light toward the peripheral portion of the insertion hole,
The resin member is
The groove of the lid member prevents the occurrence of burnt portions in the electricity storage device. The electricity storage device according to claim 5 ,
The opening in the body member is
A rectangular ring having a pair of long side openings and a pair of short side openings,
The peripheral portion of the cover member is
A rectangular ring shape having a pair of long side peripheral edges and a pair of short side peripheral edges,
The groove is
the cover member includes a pair of long side grooves located between the pair of long side peripheral portions and the insertion hole peripheral portion and extending along the long side peripheral portions,
The resin member is
The long side groove of the cover member prevents the occurrence of burnt portions in the peripheral portion of the resin member adjacent to the long side peripheral portion. The electricity storage device according to claim 5 or 6,
The groove is
an outer groove provided on an outer surface of the cover member, the outer groove having a peripheral portion-side inner surface located on the peripheral portion side and a hole peripheral portion-side inner surface located on the insertion hole peripheral portion side;
The inner surface of the outer groove on the peripheral edge side is
The electricity storage device has a shape in which the outer surface side in the thickness direction of the lid becomes farther from the peripheral edge portion. The electricity storage device according to claim 5 or 6,
The groove is
The electricity storage device further comprises an inner groove provided on an inner surface of the cover member.

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