Square battery

Abstract

To provide a square battery which prevents a laser from passing through the inside of a battery during laser welding.SOLUTION: Disclosed is a square battery 100 comprising a battery case 10 and an electrode body 20 which is stored in the battery case 10. The battery case 10 consists of a case body 12 in a square cylinder shape including an opening 13 in both ends and a sealing plate 14 which seals the opening 13. The sealing plate 14 includes a cover part 14a which covers an edge 13a of the opening of the case body 12 and an insert part 14b which enters the inside of the case body 12 from the cover part 14a along the inside of the case body 12. The cover part 14a and the case body 12 are welded along the edge 13a of the opening of the battery case 10.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a prismatic battery. [Background technology]

[0002] Japanese Patent Nos. 5504007 and 6640467 describe prismatic batteries in which the battery lid and the battery container are welded by fillet welding. Japanese Patent No. 7355235 describes a prismatic battery with a space between a cup-shaped exterior member and a lid-shaped exterior member. According to the publication, by providing this space, when the cup-shaped exterior member and the lid-shaped exterior member are welded together, the heat from the laser irradiation is transmitted to the electrode assembly located inside the exterior body, and thermal damage to the electrode assembly can be mitigated. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5504007 [Patent Document 2] Patent No. 6640467 [Patent Document 3] Patent No. 7355235 Summary of the Invention [Problem to be solved by the invention]

[0004] A primary object of the present disclosure is to provide a prismatic battery that prevents laser penetration into the battery during laser welding. [Means for solving the problem]

[0005] The prismatic battery disclosed herein includes a battery case and an electrode assembly housed in the battery case. The battery case includes a rectangular cylindrical case body with openings at both ends and a sealing plate that seals the opening. The sealing plate has a cover portion that covers the edge of the opening of the battery case and an insert portion that fits into the case body along the inside of the opening. The cover portion and the case body are welded together along the edge of the opening of the battery case. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a schematic perspective view of a prismatic battery 100. FIG. [Figure 2] FIG. 2 is a schematic cross-sectional view of a portion of the prismatic battery 100. [Figure 3] FIG. 3 is a side view of the sealing plate 14. As shown in FIG. [Figure 4] FIG. 4 is a schematic diagram showing the configuration of the electrode assembly 20 housed in the battery case 10. As shown in FIG. [Figure 5] FIG. 5 is a cross-sectional view schematically showing a welding method according to one embodiment. [Figure 6] FIG. 6 is a cross-sectional view that schematically shows the fusion zone 11a at the side of the edge 13a of the opening 13 of the case body 12. As shown in FIG. [Figure 7] FIG. 7 is a cross-sectional view that schematically shows a fusion zone 11 a at a corner 11 of an edge 13 a of an opening 13 of a case body 12 . [Figure 8] FIG. 8 is a cross-sectional view schematically showing a preferred embodiment of the fusion zone 11a at the corner 11. As shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0007] Preferred embodiments of the technology disclosed herein are described below. Matters necessary for implementing the technology disclosed herein, other than those specifically mentioned in this specification, can be understood as design matters for a person skilled in the art based on the prior art in the relevant field. The technology disclosed herein can be implemented based on the contents disclosed in this specification and the technical common sense in the relevant field. Furthermore, in the drawings described in this specification, components and parts that perform the same function are denoted by the same reference numerals, and redundant explanations may be omitted or simplified. Furthermore, the dimensional relationships (length, width, thickness, etc.) in each drawing do not necessarily reflect the actual dimensional relationships.

[0008] In this specification, the term "secondary battery" refers to a general term for an electricity storage device that can be repeatedly charged and discharged with the movement of charge carriers between positive and negative electrodes, and is a concept that encompasses so-called storage batteries (chemical batteries) such as lithium ion secondary batteries and sodium ion secondary batteries, and capacitors (physical batteries) such as lithium ion capacitors (LIC). Below, each of the main constituent materials of the secondary battery according to the present disclosure will be described. It should be noted that conventionally known materials can be used for constituent materials of secondary batteries not described here.

[0009] FIG. 1 is a schematic perspective view of a prismatic battery 100. Although not shown, a resin shrink film may be attached around the periphery of the battery case 10 as an insulating member. FIG. 2 is a schematic cross-sectional view of a portion of the prismatic battery 100. The prismatic battery 100 includes a battery case 10 and an electrode assembly 20 housed inside the battery case 10. The positive electrode terminal 30 is electrically connected to the positive electrode 22 of the electrode assembly 20 via a positive electrode current collector (not shown) inside the battery case 10. The negative electrode terminal 40 is electrically connected to the negative electrode 24 of the electrode assembly 20 via a positive electrode current collector (not shown) inside the battery case 10. Although not shown, the prismatic battery 100 here also includes an electrolyte housed inside the battery case 10. Each component will be described below in order.

[0010] 1. Battery case 10 As shown in Fig. 1, the battery case 10 consists of a case body 12 having openings 13 on both ends, and a sealing plate 14 that seals the openings 13. The battery case 10 is integrated by welding the sealing plate 14 along the edge 13a of the opening 13 to the case body 12. The corners of the sealing plate 14 become corners 11 of the battery case 10. The battery case 10 is hermetically sealed (sealed).

[0011] The case body 12 is a rectangular tube having openings 13 at both ends. The material of the case body 12 may be the same as that conventionally used, and is not particularly limited. The case body 12 is preferably made of metal, and more preferably made of, for example, aluminum, an aluminum alloy, iron, an iron alloy, or the like.

[0012] 1-1. Case body 12 The case body 12 is a rectangular cylindrical shape with openings 13 at both ends. In the embodiment shown in FIG. 1, the case body 12 has a substantially rectangular bottom surface 12a, a pair of long side surfaces 12b extending from the long sides of the bottom surface 12a and facing each other, and a top surface 12c connecting the upper ends of the pair of long side surfaces 12b. The top surface 12c is substantially rectangular. The top surface 12c faces the bottom surface 12a. The case body 12 is formed, for example, by bending a single metal plate into a cylindrical shape and joining the seams (for example, by welding). Here, a welded joint 12d is located on the top surface 12c.

[0013] 1-2. Sealing plate 14 FIG. 3 is a side view of the sealing plate 14. As shown in FIG. 3, the sealing plate 14 is a member that seals the opening 13. In this embodiment, the sealing plate 14 is a plate-shaped member that covers the entire opening 13 of the case body 12. The sealing plate 14 has a cover portion 14a and an insert portion 14b. The cover portion 14a is a portion of the sealing plate 14 that covers the edge 13a of the opening 13 of the case body 12. The insert portion 14b is a portion of the sealing plate 14 that fits into the inside of the case body 12, along the inside of the opening 13 of the case body 12.

[0014] 2. Electrode body 20 FIG. 4 is a schematic diagram showing the configuration of the electrode assembly 20 housed in the battery case 10. The electrode assembly 20 is a power-generating element of the prismatic battery 100. As shown in FIG. 4, the electrode assembly 20 includes a positive electrode 22, a negative electrode 24, and a separator 26. The electrode assembly 20 shown in FIG. 4 is a wound electrode assembly. This wound electrode assembly is produced by stacking the positive electrode 22, the negative electrode 24, and the separator 26 to form a long, strip-shaped laminate, and then winding the laminate around a winding axis WL. However, the structure of the electrode assembly 20 is not particularly limited, and may be any other conventionally known structure (such as a laminated electrode assembly).

[0015] As shown in FIG. 4, the positive electrode 22 has a positive electrode core 22c and a positive electrode active material layer 22a formed on at least one surface (both surfaces in this case) of the positive electrode core 22c.

[0016] The positive electrode core 22c is strip-shaped and made of a conductive metal such as aluminum, an aluminum alloy, nickel, or stainless steel. Here, the positive electrode core 22c is a metal foil, specifically an aluminum foil.

[0017] As shown in FIG. 4, the positive electrode active material layer 22a is provided in a strip-like shape along the longitudinal direction of the strip-shaped positive electrode substrate 22c. The positive electrode active material layer 22a contains a positive electrode active material capable of reversibly absorbing and releasing charge carriers. The positive electrode active material preferably contains at least one of Ni, Co, and Mn. For example, a lithium transition metal composite oxide such as a lithium nickel cobalt manganese composite oxide may be used. When the total solid content of the positive electrode active material layer 22a is taken as 100% by mass, the positive electrode active material may account for approximately 80% by mass or more, typically 90% by mass or more, for example, 95% by mass or more. The positive electrode active material layer 22a may contain optional components other than the positive electrode active material, such as a conductive material, a binder, various additives, etc. Examples of the conductive material include carbon materials such as carbon black (e.g., acetylene black (AB)). Examples of the binder include PVdF.

[0018] As shown in Fig. 4, the positive electrode tabs 22t protrude from the end of the electrode assembly 20 in the long side direction Y. The positive electrode tabs 22t are provided at intervals along the longitudinal direction of the strip-shaped positive electrode 22. The tabs are rectangular in shape here, but may also have various other shapes (e.g., trapezoidal). In at least a portion of the positive electrode tab 22t, a region is formed in which the positive electrode active material layer 22a is not formed and the positive electrode core 22c is exposed.

[0019] As shown in FIG. 4, the negative electrode 24 has a negative electrode core 24c and a negative electrode active material layer 24a formed on at least one surface (both surfaces in this case) of the negative electrode core 24c.

[0020] The negative electrode core 24c is strip-shaped and made of a conductive metal such as copper, a copper alloy, nickel, stainless steel, etc. Here, the negative electrode core 24c is a metal foil, specifically a copper foil.

[0021] The negative electrode active material layer 24a is provided in a strip shape along the longitudinal direction of the strip-shaped negative electrode substrate 24c. The negative electrode active material layer 24a contains a negative electrode active material (e.g., a carbon material such as graphite, or a silicon-based material such as Si or SiO) that can reversibly store and release charge carriers. When the total solid content of the negative electrode active material layer 24a is taken as 100 mass%, the negative electrode active material may account for approximately 80 mass% or more, typically 90 mass% or more, for example 95 mass% or more. The negative electrode active material layer 24a may contain optional components other than the negative electrode active material, such as a binder, a dispersant, and various additives. Examples of the binder that can be used include rubbers such as styrene butadiene rubber (SBR). Examples of the dispersant that can be used include celluloses such as carboxymethyl cellulose (CMC).

[0022] As shown in Fig. 4, the negative electrode tabs 24t protrude from the end of the electrode assembly 20 in the long side direction Y. The negative electrode tabs 24t are provided at intervals along the longitudinal direction of the strip-shaped negative electrode 24. The tabs are rectangular in shape here, but may also have various other shapes (e.g., trapezoidal). In at least a portion of the negative electrode tab 24t, a region is formed in which the negative electrode active material layer 24a is not formed and the negative electrode core 24c is exposed.

[0023] The separator 26 is a member that insulates the positive electrode active material layer 22a of the positive electrode 22 from the negative electrode active material layer 24a of the negative electrode 24. A porous resin sheet made of a polyolefin resin such as polyethylene (PE) or polypropylene (PP) is suitable for the separator 26. The separator 26 may have a heat resistance layer (HRL) containing an inorganic filler provided on the surface of the resin sheet. Examples of inorganic fillers that can be used include alumina, boehmite, aluminum hydroxide, and titania. An adhesive layer is preferably provided on one or both surfaces of the separator 26. The adhesive layer improves adhesion to the contacting positive electrode active material layer or negative electrode active material layer. The adhesive layer contains, for example, polyvinylidene fluoride (PVdF) as an adhesive component. The adhesive layer may also contain inorganic particles such as alumina and boehmite. The adhesive layer may be provided on the surface of the resin sheet or on the surface of the HRL.

[0024] As shown in FIG. 1 , the positive electrode terminal 30 and the negative electrode terminal 40 are each fixed to the battery case 10. Here, the positive electrode terminal 30 and the negative electrode terminal 40 are each fixed to opposing surfaces of the battery case 10 (specifically, the sealing plate 14), and are exposed on the outer surface of the battery case 10. Specifically, the positive electrode terminal 30 is attached to the sealing plate 14 located on one side in the long side direction Y (the right side in FIGS. 1 and 2 ). The negative electrode terminal 40 is attached to the sealing plate 14 located on the other side in the long side direction Y (the left side in FIGS. 1 and 2 ). Note that, although the positive electrode terminal 30 and the negative electrode terminal 40 are attached to the sealing plate 14 in the battery case 10 according to one embodiment, the positive electrode terminal 30 and the negative electrode terminal 40 may also be attached to the case body 12.

[0025] Here, the positive electrode terminal 30 and the negative electrode terminal 40 are arranged on an axis that extends in the long side direction Y and passes through the center of the sealing plate 14. However, the axis may be offset from the center of the sealing plate 14, for example, in the short side direction X. Furthermore, the positive electrode terminal 30 and the negative electrode terminal 40 do not have to be arranged on the axis. For example, one of the positive electrode terminal 30 and the negative electrode terminal 40 may be offset to one side in the short side direction X, and the other may be offset to the other side in the short side direction X.

[0026] Fig. 5 is a cross-sectional view schematically illustrating a welding method according to one embodiment. Fig. 5 illustrates a view in which a sealing plate 14 is attached to a case body 12 with an opening 13 facing upward. A cover portion 14a of the sealing plate 14 is welded to the case body 12 along an edge 13a of the opening 13 of the case body 12.

[0027] As shown in FIG. 5, the manufacturing method for the prismatic battery 100 includes a mounting step and a welding step. The mounting process is a process of mounting the sealing plate 14 to the opening 13 of the case body 12 so that the cover portion 14a covers the edge 13a of the opening 13 of the case body 12 and the insert portion 14b fits inside the case body 12. During mounting, a gap is generated between the opening 13 of the case body 12 and the insert portion 14b of the sealing plate 14 according to the difference between the inner and outer diameters of the opening 13 and the insert portion 14b of the sealing plate 14. In this specification, the gaps at the sides and corners 11 of the edge 13a of the opening 13 of the case body 12 are referred to as S1 and S2, respectively. Because FIG. 5 is a cross-sectional view of the side of the edge 13a of the opening 13 of the case body 12, the gap in this figure is referred to as S1. In the welding process, in order to properly weld the sealing plate 14 and the case body 12, welding is performed while they are pressed together with a holding jig. Then, a laser 11c is irradiated along the entire periphery of the opening 13 of the case body 12 at the boundary between the edge 13a of the opening 13 of the case body 12 and the cover portion 14a of the sealing plate 14 facing the edge 13a of the opening 13, thereby welding the case body 12 and the sealing plate 14 together.

[0028] In the manufacturing method for the prismatic battery 100 according to one embodiment, the case body 12 and the sealing plate 14 are welded together using the laser irradiation method described above, and the welding heat generated from the molten zone 11a during welding can be suitably diffused through the gap S1 or S2. In this manufacturing method, the laser 11c is irradiated along the entire periphery of the boundary between the edge 13a of the opening 13 of the case body 12 and the cover portion 14a of the sealing plate 14, so the corners 11 receive more energy from the laser 11c than the sides. Therefore, it is preferable that S2 at the corners 11 of the edge 13a of the opening 13 of the case body 12 is larger than S1 at the sides of the edge 13a of the opening 13 of the case body 12.

[0029] After the welding step is completed, if the gap S1 or S2 exists in a region of the sealing plate 14 that is within a depth of 0.5 mm from the surface of the sealing plate 14, where the thickness D of the sealing plate 14 is 1, the strength of the battery case 10 may be reduced. Therefore, from the perspective of preventing a reduction in the strength of the battery case 10 due to the gap S1 or S2, the region where the gap S1 or S2 exists is preferably at a thickness of 0.6 mm or more from the surface of the sealing plate 14, more preferably 0.7 mm or more, and particularly preferably 0.8 mm or more.

[0030] Here, in the welding process, as shown in FIG. 5, for example, the laser 11c may be irradiated from a direction perpendicular to the thickness D direction of the sealing plate 14. Even in this case, the insert portion 14b penetrates into the interior of the case body 12. When the sealing plate 14 and the case body 12 are pressed together during the above-described welding, a gap T due to improper pressing may occur at the boundary between the edge 13a of the opening 13 and the opposing cover portion 14a of the sealing plate 14. However, even if the laser 11c penetrates into such gap T during welding, the laser 11c hits the insert portion 14b. This prevents the laser 11c from penetrating into the space inside the case body 12 where the electrode body 20 is housed. As a result, damage to the electrode body 20 due to such laser penetration can be prevented. In order to effectively prevent the laser 11c from penetrating into the battery case 10, it is preferable that the distance between the insert portion 14b and the opening 13 of the battery case 10, in other words, the width of the gap S1 in the direction perpendicular to the thickness D direction of the sealing plate 14 (parallel to the direction of travel of the laser 11c), is as narrow as possible, and the laser 11c may be in contact with the insert portion 14b.

[0031] Fig. 6 is a cross-sectional view schematically showing a fusion zone 11a at a side portion of an edge 13a of an opening 13 of a case body 12. Fig. 7 is a cross-sectional view schematically showing a fusion zone 11a at a corner portion 11 of an edge 13a of an opening 13 of a case body 12. Note that in Figs. 6 and 7, a dashed line is drawn at the boundary of the fusion zone 11a between the case body 12 and the sealing plate 14 before welding.

[0032] As shown in Fig. 6, with insert portion 14b inserted inside case body 12, fusion zone 11a is formed around the entire boundary between edge 13a of opening 13 in case body 12 and cover portion 14a of sealing plate 14, and they are welded together. This attaches sealing plate 14 to case body 12, sealing opening 13. The gap S1 described above is formed between opening 13 in case body 12 and insert portion 14b of sealing plate 14. The shortest distance between the end of fusion zone 11a on the sealing plate 14 side and the outer surface of sealing plate 14 is designated as a.

[0033] As shown in FIG. 7 , the molten zone 11a may extend to the corner 11 of the battery case 10. As a result, a rounded corner 11 of the battery case 10 may be formed. In this embodiment, with the insert portion 14b inserted into the case main body 12, a laser is irradiated along the entire periphery of the boundary between the edge 13a of the opening 13 of the case main body 12 and the cover portion 14a of the sealing plate 14. In this case, the corner 11 of the battery case 10 is irradiated with the laser in the circumferential direction along the edge 13a of the opening 13 of the case main body 12, and therefore receives more laser energy. For this reason, the molten zone 11a tends to be larger at the corner 11 than at the side. Furthermore, as a result of the larger molten zone 11a, the molten zone 11a may reach the corner of the battery case 10, in other words, the outer corner of the cover portion 14a of the sealing plate 14. When the molten portion 11a reaches the corner of the cover portion 14a of the sealing plate 14, the corners around the periphery of the battery case 10 are rounded.

[0034] For example, in the prismatic battery 100, the periphery of the battery case 10 may be covered with a resin shrink film, which is an insulating material. As described above, by providing rounded corners around the periphery of the battery case 10, damage to the shrink film can be effectively prevented when the battery case 10 is covered with the shrink film. In this manner, the laser output may be adjusted so that an appropriate molten zone 11a is formed around the entire periphery at the boundary between the edge 13a of the opening 13 of the case body 12 and the cover portion 14a of the sealing plate 14. Furthermore, at the corners 11 of the edge 13a of the opening 13 of the case body 12, in addition to forming an appropriate molten zone 11a at the boundary between the edge 13a of the opening 13 of the case body 12 and the cover portion 14a of the sealing plate 14, the molten zone 11a may be melted to the extent that it reaches the corner of the cover portion 14a. The molten portion 11a may extend to the extent that it reaches the corners of the cover portion 14a on the surface and forms rounded corners of the cover portion 14a, but may not extend to the outer surface of the sealing plate 14. From this perspective, the thickness of the cover portion 14a and the output of the laser may be adjusted so that rounded corners of the cover portion 14a are formed by laser irradiation.

[0035] 8 is a cross-sectional view schematically illustrating a preferred embodiment of the fused portion 11a at the corner 11. As described above, from the viewpoint of forming a suitable rounded portion at the corner 11 and preventing damage to the shrink film, the shortest distance a between the end of the fused portion 11a on the surface of the corner 11 on the sealing plate 14 side and the outer surface of the sealing plate 14 is preferably as short as possible, and may be approximately 5 mm or less, preferably 3 mm or less, and more preferably 1 mm or less. Note that this distance may be 0 mm, in which case it can be said that the rounded portion extends to the outer surface of the sealing plate 14.

[0036] As shown in Fig. 6, at a side portion of the edge 13a of the opening 13 of the case body 12, if the total depth L from the surface of the battery case 10 is 1, the width of the fused portion 11a on the surface of the battery case 10 is W1, and the width of the fused portion 11a at a position corresponding to a depth of 0.5 is W2. On the other hand, as shown in Fig. 7, at a corner 11 of the edge 13a of the opening 13 of the case body 12, if the total depth L from the surface of the battery case 10 is 1, the width of the fused portion 11a on the surface of the battery case 10 is W3, and the width of the fused portion 11a at a position corresponding to a depth of 0.5 is W4. The welding conditions may be set in advance through experiments or the like so as to achieve the relationship between W1 and W2 as shown below. As described above, corner 11 receives more laser energy, so width W3 of fusion zone 11a at corner 11 is likely to be larger than width W1 of fusion zone 11a. In other words, width W3 of fusion zone 11a depends on width W1 of fusion zone 11a, and width W3 of fusion zone 11a increases as width W1 of fusion zone 11a increases. From the viewpoint of increasing width W3 of fusion zone 11a and favorably forming corner 11 into a rounded shape, it is preferable that width W1 of fusion zone 11a be large. According to the inventor's findings, W1 > W2 is desirable, and the ratio (W2 / W1) is preferably 0.8 or less, more preferably 0.75 or less, and particularly preferably 0.7 or less. On the other hand, if the value of W2 / W1 is too small, there is a risk of deterioration in welding quality. Therefore, the value of W2 / W1 is preferably 0.3 or more, more preferably 0.4 or more, and particularly preferably 0.5 or more.

[0037] According to the inventor's findings, it is preferable that the ratio (W4 / W3) be smaller than the ratio (W2 / W1). In other words, it is preferable that the difference between the width of the fusion zone 11a at the surface and the width of the fusion zone 11a at a depth of 0.5 is larger at the corners 11 of the edge 13a of the opening 13 than at the sides. According to the inventor's findings, it is preferable that W3 > W4, and the ratio (W4 / W3) is preferably less than 0.80, more preferably 0.75 or less, and particularly preferably 0.7 or less. On the other hand, if the value of W4 / W3 is too small, there is a risk of a decrease in welding quality, so the value of W4 / W3 is preferably 0.3 or more, more preferably 0.4 or more, and particularly preferably 0.5 or more.

[0038] In the above-described embodiment, the prismatic battery includes a battery case and an electrode assembly housed in the battery case. The battery case includes a rectangular cylindrical case body with openings at both ends and a sealing plate that seals the opening. The sealing plate has a cover portion that covers the edge of the opening of the case body and an insert portion that fits into the case body along the inside of the opening. The cover portion and the case body are welded along the edge of the opening of the case body.

[0039] In such a prismatic battery, damage to the electrode body can be prevented by preventing the laser from progressing into the interior of the battery case during welding.

[0040] In the above-described embodiment, when a shrink film is used on the outer periphery of the battery case, damage to the shrink film can be prevented.

[0041] In the above-described embodiment, by adjusting the ratios W2 / W1 and W4 / W3 to fall within predetermined ranges, it is possible to provide rounded corners of the battery case while favorably welding the battery case.

[0042] In the above-described embodiment, by adjusting the ratio W2 / W1 within a predetermined range, it is possible to provide rounded corners of the battery case while suitably welding the battery case.

[0043] In the above-described embodiment, by adjusting the ratio W4 / W3 to fall within a predetermined range, it is possible to provide rounded corners of the battery case while suitably welding the battery case.

[0044] In the above-described embodiment, the welding heat that may be concentrated at the welding point during welding can be diffused, thereby preventing explosions that may occur at the corners of the battery case.

[0045] In the above-described embodiment, the melting heat generated from the melted portion during welding can be effectively diffused at the corners of the battery case where the laser energy is more likely to be concentrated, thereby effectively preventing explosions that may occur at the corners of the battery case.

[0046] In the above-described embodiment, the method for manufacturing a prismatic battery includes a prismatic cylindrical case body having openings at both ends and a sealing plate that seals the openings. The sealing plate has a cover portion that covers the edge of the opening of the case body and an insert portion that fits into the case body from the cover portion along the inside of the case body. The method then includes the following steps: an attachment step of attaching the sealing plate to the opening of the case body so as to cover the edge of the opening of the case body with the cover portion and insert the insert portion into the interior of the case body; and a welding step of irradiating a boundary portion between an edge of the opening of the case body and the cover portion of the sealing plate facing the edge of the opening along the entire periphery of the opening of the case body with a laser, thereby welding the case body and the sealing plate together; Includes.

[0047] In the above-described method for manufacturing a prismatic battery, damage to the electrode body can be prevented by preventing the laser from progressing into the interior of the battery case during welding.

[0048] In the above-described method for manufacturing a prismatic battery, damage to the electrode body can be suitably prevented by preventing the laser from progressing into the interior of the battery case during welding.

[0049] In the above-described method for manufacturing a prismatic battery, when a resin shrink film is used as an insulating member for the outer periphery of the battery case, damage to the shrink film can be prevented.

[0050] In the above-described method for manufacturing a prismatic battery, by adjusting the ratios W2 / W1 and W4 / W3 within predetermined ranges, it is possible to manufacture a prismatic battery in which the corners of the battery case have R and the battery case and the sealing plate are suitably welded.

[0051] In the manufacturing method of the prismatic battery described above, by adjusting the ratio W2 / W1 within a predetermined range, it is possible to manufacture a prismatic battery in which the corners of the battery case have R and the battery case and the sealing plate are suitably welded.

[0052] In the manufacturing method of the prismatic battery described above, by adjusting the ratio W4 / W3 within a predetermined range, it is possible to manufacture a prismatic battery in which the corners of the battery case have R and the battery case and the sealing plate are suitably welded.

[0053] The above-described manufacturing method for a prismatic battery can diffuse welding heat that can concentrate at the welding points during welding, thereby preventing explosions that can occur at the corners of the battery case.

[0054] The above-described manufacturing method for a prismatic battery can effectively diffuse the heat generated from the fusion zone during welding at the corners of the battery case, where the laser energy is more likely to be concentrated, thereby effectively preventing explosions that may occur at the corners of the battery case.

[0055] The technology disclosed herein has been described in various ways. Unless otherwise specified, the embodiments and the like described herein do not limit the present invention. Furthermore, the technology disclosed herein can be modified in various ways, and as long as no particular problems arise, each component and each process described herein can be omitted or combined as appropriate. Furthermore, this specification includes the disclosures described in the following sections.

[0056] Section 1: A battery case and an electrode assembly housed in the battery case; Equipped with The battery case is a square cylindrical case body having openings at both ends; a sealing plate that seals the opening; Equipped with The sealing plate is a cover portion covering the edge of the opening of the case body; an insert portion that is inserted into the case body along the inside of the opening of the case body; and The cover and the case body are welded together along the edge of the opening of the case body. Square battery.

[0057] Section 2: Item 1. The prismatic battery according to item 1, wherein the battery case has at least one corner rounded.

[0058] Section 3: At the edge of the opening of the case body, the width of the molten portion on the surface of the case body is defined as W1, and the total depth from the surface of the battery case is defined as L=1, where W2 is the width of the molten portion at a position corresponding to a depth of 0.5; At the corner of the edge of the opening of the case body, if the width of the molten portion on the surface of the case body is W3 and the total depth from the surface of the battery case is L, then the width of the molten portion at a position corresponding to a depth of 0.5 is W4. Item 3. The prismatic battery according to item 1 or 2, wherein the ratio W2 / W1 of W2 to W1 is greater than the ratio W4 / W3 of W4 to W3.

[0059] Section 4: Item 4. The prismatic battery according to item 3, wherein the ratio W2 / W1 is 0.3 or more and 0.8 or less.

[0060] Section 5 Item 4. The prismatic battery according to item 3, wherein the ratio W4 / W3 is 0.3 or more and 0.8 or less.

[0061] Item 6: Item 6. The prismatic battery according to any one of items 1 to 5, wherein a gap is formed between the case body and the sealing plate where the case body and the sealing plate are not welded.

[0062] Section 7: Item 7. The prismatic battery according to item 6, wherein the gap at the side edge of the opening of the case body is smaller than the gap at the corner edge of the opening of the case body.

[0063] Section 8: a square cylindrical case body having openings at both ends; a sealing plate that seals the opening; A method for manufacturing a prismatic battery comprising: The sealing plate is a cover portion that covers the edge of the opening of the case body; an insert portion that extends from the cover portion into the case body along the inside of the opening of the case body; The method comprises the steps of: an attachment step of attaching the sealing plate to the opening of the case body so that the cover portion covers the edge of the opening of the case body and the insert portion is inserted into the inside of the case body; and a welding step of irradiating a boundary portion between an edge of the opening of the case body and the cover portion of the sealing plate facing the edge of the opening along the entire periphery of the opening of the case body with a laser, thereby welding the case body and the sealing plate together; A method for manufacturing a prismatic battery comprising the steps of:

[0064] Section 9: Item 9. The method for manufacturing a prismatic battery according to Item 8, wherein the welding step involves irradiating the sealing plate with the laser in a direction perpendicular to the thickness direction of the sealing plate.

[0065] Section 10: Item 10. The method for producing a prismatic battery according to item 8 or 9, wherein at least one corner of the battery case is rounded.

[0066] Section 11: At the edge of the opening of the case body, the width of the molten portion on the surface of the case body is defined as W1, and the total depth from the surface of the battery case is defined as L=1, where W2 is the width of the molten portion at a position corresponding to a depth of 0.5; At the corner of the edge of the opening of the case body, if the width of the molten portion on the surface of the case body is W3 and the total depth from the surface of the battery case is L, then the width of the molten portion at a position corresponding to a depth of 0.5 is W4. 11. The method for manufacturing a prismatic battery according to claim 8, wherein the case body and the sealing plate are welded together so that the ratio W2 / W1 of W2 to W1 is greater than the ratio W4 / W3 of W4 to W3.

[0067] Section 12: Item 12. The method for manufacturing a prismatic battery according to Item 11, wherein the case body and the sealing plate are welded together so that the ratio W2 / W1 is 0.3 or more and 0.8 or less.

[0068] Section 13: Item 12. The method for manufacturing a prismatic battery according to Item 11, wherein the case body and the sealing plate are welded together so that the ratio W4 / W3 is 0.3 or more and 0.8 or less.

[0069] Section 14: Item 14. The method for manufacturing a prismatic battery according to any one of items 8 to 13, wherein a gap is formed between the case body and the sealing plate where the case body and the sealing plate are not welded.

[0070] Section 15: Item 15. The method for manufacturing a prismatic battery according to item 14, wherein the case body and the sealing plate are welded together so that the gap at the edge of the opening of the case body is smaller than the gap at the corner of the opening of the case body. [Explanation of symbols]

[0071] 10 Battery case 11 Corner 11a Welded part 11c Laser 12 Case body 12a Bottom 12b long side 12c Top 12d Welded joints 13 Aperture 13a Edge of opening 14 Sealing plate 14a Cover part 14b Insert part 20 Electrode body 22 Positive electrode 22a Cathode active material layer 22c positive electrode core 22t Positive electrode tab 24 Negative electrode 24a Negative electrode active material layer 24c negative electrode core 24t negative electrode tab 26 Separator 30 Positive terminal 40 Negative terminal 100 square batteries

Claims

1. A battery case and an electrode assembly housed in the battery case; Equipped with The battery case is a square cylindrical case body having openings at both ends; a sealing plate that seals the opening; Equipped with The sealing plate is a cover portion covering the edge of the opening of the case body; an insert portion that is inserted into the case body along the inside of the opening of the case body; and The cover and the case body are welded together along the edge of the opening of the case body. Square battery.

2. The prismatic battery according to claim 1 , wherein the battery case has at least one rounded corner.

3. At the edge of the opening of the case body, the width of the molten portion on the surface of the case body is defined as W1, and the total depth L from the surface of the battery case is defined as 1, where W2 is the width of the molten portion at a position corresponding to a depth of 0.5; At the corner of the edge of the opening of the case body, when the width of the molten portion on the surface of the case body is W3 and the total depth L from the surface of the battery case is 1, the width of the molten portion at a position corresponding to a depth of 0.5 is W4, 3. The prismatic battery according to claim 1, wherein a ratio W2 / W1 of W2 to W1 is greater than a ratio W4 / W3 of W4 to W3.

4. 4. The prismatic battery according to claim 3, wherein the ratio W2 / W1 is equal to or greater than 0.3 and equal to or less than 0.

8.

5. 4. The prismatic battery according to claim 3, wherein the ratio W4 / W3 is equal to or greater than 0.3 and equal to or less than 0.

8.

6. The prismatic battery according to claim 1 or 2, wherein a gap is formed between the case body and the sealing plate where the case body and the sealing plate are not welded.

7. The prismatic battery according to claim 6 , wherein the gap at the side edge of the opening of the case body is smaller than the gap at the corner edge of the opening of the case body.

8. a square cylindrical case body having openings at both ends; a sealing plate that seals the opening; A method for manufacturing a prismatic battery comprising: The sealing plate is a cover portion that covers the edge of the opening of the case body; an insert portion that extends from the cover portion into the case body along the inside of the opening of the case body; The method comprises the steps of: an attachment step of attaching the sealing plate to the opening of the case body so that the cover portion covers the edge of the opening of the case body and the insert portion is inserted into the interior of the case body; and a welding step of irradiating a boundary portion between an edge of the opening of the case body and the cover portion of the sealing plate facing the edge of the opening along the entire periphery of the opening of the case body with a laser, thereby welding the case body and the sealing plate together; A method for manufacturing a prismatic battery comprising the steps of:

9. The method for manufacturing a prismatic battery according to claim 8 , wherein the welding step involves irradiating the sealing plate with the laser in a direction perpendicular to a thickness direction of the sealing plate.

10. The method for manufacturing a prismatic battery according to claim 8 , wherein at least one corner of the battery case is rounded.

11. At the edge of the opening of the case body, the width of the molten portion on the surface of the case body is defined as W1, and the total depth L from the surface of the battery case is defined as 1, where W2 is the width of the molten portion at a position corresponding to a depth of 0.5; At the corner of the edge of the opening of the case body, when the width of the molten portion on the surface of the case body is W3 and the total depth L from the surface of the battery case is 1, the width of the molten portion at a position corresponding to a depth of 0.5 is W4, 11. The method for manufacturing a prismatic battery according to claim 8, wherein the case body and the sealing plate are welded together so that a ratio W2 / W1 of W2 to W1 is greater than a ratio W4 / W3 of W4 to W3.

12. The method for manufacturing a prismatic battery according to claim 11, wherein the case body and the sealing plate are welded together so that the ratio W2 / W1 is 0.3 or more and 0.8 or less.

13. The method for manufacturing a prismatic battery according to claim 11, wherein the case body and the sealing plate are welded together so that the ratio W4 / W3 is 0.3 or more and 0.8 or less.

14. The method for manufacturing a prismatic battery according to claim 8 or 10, wherein a gap is formed between the case body and the sealing plate where the case body and the sealing plate are not welded.

15. 15. The method for manufacturing a prismatic battery according to claim 14, wherein the case body and the sealing plate are welded together so that the gap at the side edge of the opening of the case body is smaller than the gap at the corner edge of the opening of the case body.

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