Battery case, method for manufacturing battery case, and battery

Abstract

A battery case according to one aspect of the present disclosure comprises a body in which a through-hole is provided, and a lid part which seals the through-hole. At least a portion of the body is configured from a surface treatment plate having a base plate and a surface treatment layer that covers the surface of the base plate. The through-hole is provided in the surface treatment plate. The surface treatment plate has a bent part that is provided along the edge of the through-hole and that protrudes outward from the battery case. The end surface of the tip of the bent part is excluded from the inner surface of the battery case.

Description

Battery case, method for manufacturing a battery case, and battery

[0001] The present disclosure relates to a battery case, a method for manufacturing a battery case, and a battery. This application claims priority based on Japanese Patent Application No. 2024-180699 filed in Japan on October 16, 2024, and incorporates the content thereof herein.

[0002] The battery case, which is an exterior material of the battery, has through-holes used as a liquid injection port, a cracking valve port, and the like.

[0003] The liquid injection port is used to supply an electrolytic solution into the battery case. The liquid injection port is sealed by a liquid injection plug after the electrolytic solution is injected into the battery case.

[0004] The cracking valve port is a part that releases the pressure inside the battery case when the pressure inside the battery case rises. The cracking valve port is sealed by a cracking valve. The cracking valve is a kind of safety valve and opens when a predetermined pressure is applied.

[0005] In the present disclosure, the liquid injection port and the cracking valve port are referred to as through-holes. Also, members that seal the through-holes, such as the liquid injection plug and the cracking valve, are referred to as lid parts. Patent Documents 1 to 3 disclose various methods for sealing the through-holes of the battery case.

[0006] Japanese Unexamined Patent Application Publication No. 2019-145376 Japanese Unexamined Patent Application Publication No. 2019-145294 Japanese Unexamined Patent Application Publication No. 2019-44928

[0007] In recent years, with the increase in the production volume of electric vehicles, the requirements for improving the volume energy density and weight energy density of batteries have been increasing. In order to meet such requirements, the inventors of the present invention have tried to use a steel plate as the material of the battery case. The materials of conventional battery cases are aluminum plates, stainless steel plates, and the like. Steel plates are easier to improve in workability and strength than aluminum plates and stainless steel plates. By changing the material of the battery case from an aluminum plate and a stainless steel plate to a steel plate, the thickness of the battery case can be reduced, the inner dimension can be increased without changing the outer dimension, and the volume energy density and weight energy density of the battery can be improved.

[0008] However, the inner surface of the battery case requires high corrosion resistance. This is because the inside of the battery case is filled with a highly corrosive electrolyte. If metal components from the battery case leach into the electrolyte, the battery's performance will deteriorate.

[0009] Steel plates have lower corrosion resistance than aluminum and stainless steel plates. Therefore, when using steel plates as the material for a battery case, it is necessary to provide a surface treatment layer on the surface of at least the steel plate forming the inner surface of the battery case. The surface treatment layer is, for example, a Ni-type coating layer.

[0010] The inventors attempted to use a surface-treated plate, such as a Ni-plated steel sheet, as the material for the battery case. As a result, the inventors found that the Ni-plated layer has sufficient corrosion resistance to the electrolyte. On the other hand, it also became clear that corrosion of the surface-treated plate is prone to progressing in through-holes such as the electrolyte filling port and the opening valve port. In particular, the amount of corrosion in the through-holes was large when the battery case was a neutral can. A neutral can is a battery case that is electrically insulated from the positive and negative electrodes of the battery.

[0011] Patent documents 1 to 7 disclose various methods for sealing through-holes in battery cases. However, these documents do not disclose that through-holes in battery cases made of surface-treated plates are susceptible to corrosion. Furthermore, these documents do not disclose specific methods for improving the corrosion resistance of through-holes.

[0012] In view of the above circumstances, this disclosure aims to provide a battery case in which at least a portion is composed of a surface-treated plate and the through-holes provided in the surface-treated plate have high corrosion resistance, a method for manufacturing the same, and a battery.

[0013] The gist of this disclosure is as follows:

[0014] (1) A battery case according to one aspect of the present disclosure comprises a main body portion having a through hole and a lid portion sealing the through hole, wherein at least a part of the main body portion is composed of a surface treatment plate having a base plate and a surface treatment layer covering the surface of the base plate, the through hole is provided in the surface treatment plate, the surface treatment plate is provided along the edge of the through hole and has a bent portion that protrudes toward the outside of the battery case, and the end face of the tip of the bent portion is excluded from the inner surface of the battery case. (2) Preferably, in the battery case described in (1) above, the lid portion is made of metal, the base plate is a metal plate, the surface treatment layer is plating, the battery case further comprises a weld bead joining the lid portion and the bent portion of the surface treatment plate, the weld bead is disposed between the end face of the bent portion and the inner surface of the battery case. (3) Preferably, in the battery case described in (1) or (2) above, the lid is made of metal, the base plate is a metal plate, the surface treatment layer is plated, and the battery case further comprises a weld bead that joins the lid and the bent portion of the surface treatment plate, the weld bead being positioned at the tip of the bent portion and covering the end face. (4) Preferably, in the battery case described in any one of (1) to (3) above, the lid is a rivet. (5) Preferably, in the battery case described in any one of (1) to (4) above, the end face of the bent portion is located outside the edge of the through hole and spaced apart from the edge of the through hole in a plan view along a direction perpendicular to the surface on which the through hole is provided. (6) Preferably, in the battery case described in any one of (1) to (5) above, the ratio P / t of the amount of protrusion P of the bent portion, which is the height of the bent portion with respect to the outer surface of the main body portion around the base end of the bent portion, to the plate thickness t of the main body portion around the base end is 0.2 to 30. (7) Preferably, in the battery case described in any one of (1) to (6) above, the through hole is a liquid injection port or a cleavage valve port. (8) Preferably, in the battery case described in any one of (1) to (7) above, the base plate is a steel plate and the surface treatment layer is a Ni-based plating layer.(9) Preferably, in the battery case described in any of (1) to (8) above, the thickness of the surface-treated plate in which the through-hole is formed is 0.1 to 1.4 mm.

[0015] (10) A method for manufacturing a battery case according to another aspect of the present disclosure comprises the steps of forming a preliminary through hole in a surface treatment plate having a base plate and a surface treatment layer covering the surface of the base plate, a main body having the surface treatment plate having a base plate and a surface treatment layer covering the surface of the base plate, bending the surface treatment plate around the preliminary through hole toward the outside of the main body to form a bent portion and a through hole, and installing a lid portion on the bent portion to seal the through hole, wherein when installing the lid portion on the bent portion, the end face of the tip of the bent portion is excluded from the inner surface of the battery case. (11) Preferably, in the method for manufacturing a battery case according to (10) above, the lid portion is made of metal, the base plate is made of metal plate, the surface treatment layer is plated, and when installing the lid portion on the bent portion, the lid portion is welded to the bent portion and the weld bead is placed between the end face and the inner surface of the battery case. (12) Preferably, in the method for manufacturing a battery case described in (10) or (11) above, the lid is made of metal, the base plate is made of metal, the surface treatment layer is plated, and when the lid is installed on the bent portion, the lid is welded to the bent portion, and the weld bead is placed on the tip of the bent portion so as to cover the end face. (13) Preferably, in the method for manufacturing a battery case described in any one of (10) to (12) above, the lid is made of rivets. (14) Preferably, in the method for manufacturing a battery case described in any one of (10) to (13) above, the ratio P / t of the amount of protrusion P of the bent portion, which is the height of the bent portion with respect to the outer surface of the main body portion around the base end of the bent portion, and the plate thickness t of the main body portion around the base end is 0.2 to 30. (15) Preferably, in the method for manufacturing a battery case described in any one of (10) to (14) above, when bending the surface treatment plate, the end face of the bent portion is positioned outside the edge of the through hole and separated from the edge of the through hole in a plan view along a direction perpendicular to the surface on which the through hole is provided. (16) Preferably, in the method for manufacturing a battery case described in any one of (10) to (15) above, the through hole is used as a liquid injection port or a cleavage valve port. (17) Preferably, in the method for manufacturing a battery case described in any one of (10) to (16) above, the base plate is a steel plate and the surface treatment layer is a Ni-based plating layer.(18) Preferably, in the method for manufacturing a battery case described in any one of the above items (10) to (17), the thickness of the surface treatment plate near the through hole is 0.1 to 1.4 mm.

[0016] (19) A battery according to another aspect of the present disclosure comprises a battery case as described in any one of (1) to (9) above. (20) Preferably, in the battery described in (19) above, the battery case is electrically insulated from the electrodes.

[0017] According to this disclosure, it is possible to provide a battery case in which at least a portion is made of a surface-treated plate and the through holes provided in the surface-treated plate have high corrosion resistance, a method for manufacturing the same, and a battery.

[0018] This is a perspective view of an example of a battery with a rectangular battery case. This is a plan view of the lid and through-holes along a direction perpendicular to the surface in which the through-holes are provided. This is a cross-sectional view of the lid and through-holes in Figure 2A along the line IIB-IIB. This is a cross-sectional view of an example of a conventional lid and through-hole. This is a cross-sectional view of another example of a conventional lid and through-hole. This is a cross-sectional view of a battery case in which the end face of the bent portion is covered with a weld bead. This is a cross-sectional view of a battery case in which the lid is riveted. This is a cross-sectional view of a battery case in which the lid is blind riveted during the manufacturing stage. This is a cross-sectional view of a battery case in which the lid is blind riveted. This is a cross-sectional view of a battery case in which the bending angle θ of the bent portion is approximately 135 degrees. This is a cross-sectional view of a battery case in which the bending angle θ of the bent portion is approximately 45 degrees. This is a schematic diagram illustrating the bending angle θ of the bent portion, the protrusion amount P of the bent portion, the size X of the bent portion, and the size Y of the through-hole.

[0019] The following description will explain, with reference to the drawings, a battery case and its manufacturing method according to embodiments of this disclosure, as well as the battery itself. The embodiments described below are general or specific examples. The numerical values, shapes, materials, components, arrangement and connection configurations of components, manufacturing processes, and the order of manufacturing processes shown in the following embodiments are examples only and are not intended to limit this disclosure. Dimensions in each drawing are not strictly illustrated. For example, the surface treatment layer is depicted as being extremely thicker in the drawings than it actually is. The ratio of the diameter of the through-hole to the thickness of the surface treatment plate shown in the drawings may also differ from the actual product. Unless otherwise specified, the term "cross-section" refers to a surface that passes through the center of the through-hole and is perpendicular to the outer surface of the main body around the base end of the bent portion.

[0020] (1. Battery Case 1) The battery case 1 according to this embodiment is an exterior material for a battery 2. The type of battery 2 is not particularly limited. For example, it is preferable to use the battery case 1 according to this disclosure as an exterior material for a lithium-ion battery. The shape of the battery case 1 is also not particularly limited. It is preferable to make the battery case 1 cylindrical, rectangular, or pouch-type. When using the battery case 1 according to this disclosure as an exterior material for a battery 2 of an electric vehicle, the shape of the battery case 1 can be, for example, cylindrical.

[0021] The battery case 1 according to this embodiment comprises a main body portion 11 having a through hole 112 and a lid portion 12 that seals the through hole 112, wherein at least a part of the main body portion 11 is composed of a surface treatment plate 111 having a base plate 1111 and a surface treatment layer 1112 that covers the surface of the base plate 1111, the through hole 112 is provided in the surface treatment plate 111, the surface treatment plate 111 is provided along the edge of the through hole 112 and has a bent portion 113 that protrudes toward the outside of the battery case 1, and the end face 1131 of the tip of the bent portion 113 is excluded from the inner surface 14 of the battery case 1. The surface treatment layer 1112 may be provided only on the inner surface side of the battery case 1, or it may be provided on both the inner surface side and the outer surface side of the battery case 1.

[0022] Figure 1 shows an example of a battery 2 equipped with a rectangular battery case 1. Figure 2A shows a plan view of the lid 12 and the through hole 112. Figure 2B shows a cross-sectional view of the lid 12 and the through hole 112 along the IIB-IIB line. For reference, Figures 3A and 3B show cross-sectional views of the lid 32, the through hole 312, and the weld bead 33 of a conventional battery case.

[0023] (Example of the overall structure of the main body 11) The main body 11 of the battery case 1 illustrated in Figure 1 comprises a top plate 11A, a side plate 11B, and a bottom plate 11C. The top plate 11A is provided with an electrolyte injection port 112A, which will be described later. When injecting electrolyte, it is preferable to hold the battery case 1 with the top plate 11A facing upwards. On the other hand, when using the battery 2, the battery case 1 may be held in any orientation. For example, as shown in Figure 1, the battery case 1 and battery 2 may be installed with the top plate facing horizontally.

[0024] The top plate 11A, side plates 11B, and bottom plate 11C may be joined by means of welding, crimping, or other means. Alternatively, these components may be integrally molded. For example, the side plate 11B and the top plate 11A or bottom plate 11C can be integrally molded by deep drawing of the raw material. It is preferable that the materials of the top plate 11A, side plates 11B, and bottom plate 11C are the same, but they may be different.

[0025] In the battery case 1 illustrated in Figure 1, the positive and negative electrodes are arranged separately on the top plate 11A and the bottom plate 11C. When the battery 2 is installed in the electric vehicle, the electrodes 21 are oriented toward the side of the electric vehicle. A battery case 1 having such a configuration is called a lateral terminal can. On the other hand, both the positive and negative electrodes may be arranged on either the top plate 11A or the bottom plate 11C. Furthermore, the battery case 1 may be configured so that when the battery 2 is installed in the electric vehicle, the electrodes are oriented toward the upper or lower side of the electric vehicle.

[0026] Furthermore, electrode bodies and electrolyte, etc., not shown, are arranged inside the main body 11 in Figure 1. The electrode bodies are inserted into the battery case 1 through an electrode insertion opening (not shown) provided on the top plate 11A and are electrically connected to the battery case 1. If the battery case 1 is a neutral can, an insulating material is inserted between the edge of the electrode insertion opening and the electrode 21. The insulating material is, for example, a resin component such as a gasket or packing.

[0027] (Through-hole 112 and lid portion 12) The battery case 1 according to this embodiment has a through-hole 112 and a lid portion 12 that seals the through-hole 112. Examples of the through-hole 112 are the liquid injection port 112A and the cleavage valve port 112B. Examples of the lid portion 12 are the liquid injection plug 12A and the cleavage valve 12B. The through-hole 112 and the lid portion 12 will be described below with reference to Figure 1.

[0028] The top plate 11A of the main body 11 in Figure 1 is provided with an electrolyte inlet 112A and an electrolyte plug 12A that seals the electrolyte inlet 112A. The electrolyte inlet 112A is used to inject the electrolyte 22 into the main body 11. After the electrolyte 22 has been injected, the electrolyte inlet 112A is sealed by the electrolyte plug 12A.

[0029] The top plate 11A of the main body 11 in Figure 1 is further provided with a rupture valve opening 112B and a rupture valve 12B that seals the rupture valve opening 112B. If the pressure inside the battery case 1 rises in some abnormal situation, the rupture valve 12B will rupture. Then, the pressure inside the battery case 1 will be released through the rupture valve opening 112B. This ensures the safety of the battery case 1 in the event of an abnormal situation.

[0030] In this embodiment, the liquid injection port 112A and the cleavage valve port 112B are referred to as the "through hole 112," and the liquid injection plug 12A and the cleavage valve 12B are referred to as the "lid portion 12." Figure 2A shows an enlarged plan view of an example of the through hole 112 and the lid portion 12 that seals the through hole 112. Figure 2B shows a cross-sectional view of the lid portion 12 and the through hole 112 shown in Figure 2A, along with a section IIB-IIB. In the configurations illustrated in Figures 2A and 2B, the lid portion 12 is joined to the main body portion 11 by a weld bead 13. On the other hand, as illustrated in Figures 5 and 6B, if the lid portion 12 is riveted, a weld bead 13 is not required.

[0031] As shown in Figure 3A, the base plate 3111 is exposed at the edges of the liquid filling port and the opening valve port in conventional battery cases. Furthermore, in conventional battery cases, resin materials such as gaskets are not usually applied to the edges of the liquid filling port and the opening valve port. Therefore, in conventional battery cases like the one shown in Figure 3A, the through hole 312 has problems with corrosion resistance.

[0032] For convenience, in the following explanation, the electrode insertion port in the battery 2 of Figure 1 will be considered not to correspond to the "through hole 112" described above. The corrosion resistance of the edge of the electrode insertion port can be improved by the resin material used as an insulating material. Therefore, in this embodiment, the liquid injection port 112A and the opening valve 12B are distinguished from the electrode insertion port. However, in order to further improve the corrosion resistance of the electrode insertion port, the configuration of the through hole 112 in the battery case 1 according to this embodiment may be applied to the electrode insertion port.

[0033] The material of the lid portion 12 is not particularly limited. For example, it is preferable to use the same material for the lid portion 12 as the material for the bent portion 113, which will be described later. This further improves the corrosion resistance at the contact point between the lid portion 12 and the bent portion 113. Therefore, the lid portion 12 may be made of a surface-treated plate.

[0034] When the lid portion 12 and the bent portion 113 are joined by a weld bead 13, suitable examples of the material for the lid portion 12 are nickel-plated steel, stainless steel, nickel, and copper. The material for the bent portion 113 is a surface-treated plate 111, which will be described later, and a suitable example of this is nickel-plated steel sheet. When aluminum and steel are welded together, a thick intermetallic compound is formed in the weld bead 13, reducing the joint strength. Therefore, when the bent portion 113 is a plated steel sheet and the lid portion 12 and the bent portion 113 are joined by a weld bead 13, it is preferable that the material for the lid portion 12 be something other than aluminum.

[0035] When the lid portion 12 and the bent portion 113 are mechanically joined, preferred materials for the lid portion 12 are nickel-plated steel, stainless steel, nickel, aluminum, and copper. The material for the bent portion 113 is a surface-treated plate 111, which will be described later, and a preferred example thereof is nickel-plated steel sheet. When the lid portion 12 and the bent portion 113 are mechanically joined, the material for the lid portion 12 may be aluminum.

[0036] The thickness of the lid 12 is preferably selected according to its intended use. For example, if the lid 12 is a liquid filling port, it is preferable that the thickness of the lid 12 be the same as the thickness of the top plate 11A. On the other hand, if the lid 12 is a cleavage valve, it is preferable that the thickness of the lid 12 be less than the thickness of the top plate 11A. This is because the cleavage valve needs to be the weakest point in the battery case 1.

[0037] (Position of through-hole 112) In the battery case 1 according to this embodiment, at least a part of the main body 11 is made of a surface-treated plate 111. The through-hole 112 is provided in the surface-treated plate 111. In the battery 2 and battery case 1 illustrated in Figure 1, at least the top plate 11A on which the through-hole 112 is provided is made of the surface-treated plate 111. Not only the top plate 11A, but the entire main body case may be made of the surface-treated plate 111. On the other hand, only the top plate 11A may be made of the surface-treated plate 111, and the other members may be made of highly corrosion-resistant materials such as aluminum plates or stainless steel plates. The battery case 1 may have both through-holes 112 provided in the surface-treated plate 111 and through-holes 112 provided in a plate that does not have a surface-treated layer 1112. That is, it is sufficient that there is one or more through-holes 112 provided in the surface-treated plate 111.

[0038] (Surface treatment plate 111) As shown in Figure 2B, the surface treatment plate 111 has a base plate 1111 and a surface treatment layer 1112 that covers the surface of the base plate 1111. For the sake of explanation, the surface treatment layer 1112 is depicted as thick in Figure 2B, etc. However, the actual thickness of the surface treatment layer 1112 is usually much smaller than the thickness of the base plate 1111.

[0039] The surface treatment layer 1112 prevents contact between the base plate 1111 and the electrolyte 22. This improves the corrosion resistance of the base plate 1111. Therefore, corrosion resistance is not necessarily required for the base plate 1111. The surface treatment layer 1112 is disposed on at least the surfaces of the base plate 1111 that constitute the inner surface 14 of the battery case 1. Preferably, the surface treatment layer 1112 is disposed on both sides of the base plate 1111.

[0040] Note that the "surface" of the surface treatment plate 111 and the base plate 1111 is distinct from the "end face". The end faces of the surface treatment plate 111 and the base plate 1111 refer to the surfaces that form the edges of the respective surface treatment plate 111 and base plate 1111. For example, the edge of a through hole 312 formed by simple drilling in the surface treatment plate 311, as illustrated in Figure 3A, is the end face 3131 of the surface treatment plate 311. Examples of drilling processes include drilling, punching, and laser cutting. The surface treatment layer 3112 is substantially absent from the end face 3131 in Figure 3A. The base plate 3111 is exposed at the end face 3131 in Figure 3A.

[0041] A preferred example of the surface treatment plate 111 is a plated metal sheet. In a plated metal sheet, the base plate 1111 is a metal sheet, and the surface treatment layer 1112 is a plating layer. A further preferred example of the surface treatment plate 111 is a Ni-based plated steel sheet. In a Ni-based plated steel sheet, the base plate 1111 is a steel sheet, and the surface treatment layer 1112 is a Ni-based plating layer. A Ni-based plating layer is a plating layer whose main component is Ni, and which optionally contains alloying elements such as Co, Fe, and W. Specific examples of the surface treatment plate 111 will be described later.

[0042] (Bending portion 113) As shown in FIG. 2B, the surface treatment plate 111 has a bending portion 113. As shown in FIG. 2A, when the through hole 112 is viewed from the top plate side, the bending portion 113 is provided along the edge of the through hole 112. The bending portion 113 protrudes toward the outside of the battery case 1. The bending portion 113 is formed by drilling a hole in the surface treatment plate 111 and then bending the periphery of the hole to the outside of the battery case. Therefore, the bending portion 113 has a surface treatment layer 1112 and a bottom plate 1111, similar to the peripheral portion of the through hole 112. The tip of the bending portion 113 illustrated in the cross-sectional view of FIG. 2B is an end face 1131. The end face 1131 is formed when a hole is drilled in the surface treatment plate 111. The surface treatment layer 1112 does not substantially exist on the end face 1131 at the tip of the bending portion 113.

[0043] (Position of the end face 1131 at the tip of the bending portion 113) As shown in FIG. 2B, the end face 1131 at the tip of the bending portion 113 is excluded from the inner surface 14 of the battery case 1. The inner surface 14 of the battery case 1 is the region where the electrolyte 22 contacts when the electrolyte 22 is injected into the battery case 1. For example, when the through hole 112 is sealed with a rivet, a very fine gap may occur between the through hole 112 and the rivet. However, the surface that constitutes a gap narrow enough to prevent the intrusion of the electrolyte 22 is not regarded as the inner surface 14 of the battery case 1.

[0044] The position of the end face 1131 is not particularly limited as long as it is excluded from the inner surface 14 of the battery case 1. The method for excluding the end face 1131 from the inner surface 14 of the battery case 1 is also not particularly limited. For example, in the configuration shown in FIG. 2B, a welding bead 13 is provided between the end face 1131 and the inner surface 14 of the battery case 1. For example, in the configuration shown in FIG. 4, the end face 1131 is covered by the welding bead 13. For example, in the configuration shown in FIG. 5, the contact portion between the rivet and the bending portion 113 is arranged between the end face 1131 and the inner surface 14 of the battery case 1. In any configuration, the end face 1131 is excluded from the inner surface 14 of the battery case 1.

[0045] (Effects) In the battery case 1 according to this embodiment, through holes 112, which are used as liquid injection ports 112A and cleavage valve ports 112B, etc., are provided in the surface treatment plate 111. The surface treatment layer 1112 can improve the corrosion resistance of the main body portion 11 of the battery case 1 in the area surrounding the through holes 112.

[0046] However, the inventors have found that there is a high risk of corrosion of the main body 11 at the edge of the through hole 112. This is thought to be because the surface treatment layer 1112 is substantially absent at the end face 1131 that constitutes the edge of the through hole 112, and the base plate 1111 is exposed. Figure 3A shows a schematic cross-sectional view of a through hole 312 formed by simple drilling in the surface treatment plate 311. At the edge of the through hole 312 formed by drilling, i.e., the end face 3131, the corrosion resistance improvement effect of the surface treatment layer 3112 cannot be obtained. For the reasons above, it is presumed that the electrolyte 22 corrodes the base plate 3111 at the end face 3131 of the through hole 312.

[0047] The inventors of the present invention repeatedly studied a method for enhancing the corrosion resistance of the through-hole 112. Then, as illustrated in FIGS. 2B, FIG. 4, FIG. 5, etc., the inventors bent the surface treatment plate 111 around the through-hole 112 to the outside of the battery case 1 and excluded the end face 1131 from the inner surface 14 of the battery case 1. According to the battery case 1 according to the present embodiment, it is possible to prevent contact between the end face 1131 where the surface treatment layer 1112 is not formed, which is formed at the tip of the bent portion 113, and the electrolytic solution 22. As a result, the corrosion resistance of the through-hole 112 is dramatically enhanced. Incidentally, it is difficult to enhance the corrosion resistance of the through-hole only by providing a bent portion in the through-hole. It is necessary to exclude the end face from the inner surface of the battery case. The battery case shown in FIG. 3B has a bent portion 313 formed by bending the surface treatment plate 311 around the through-hole 312 to the outside of the battery case 1. However, in the bent portion 313 shown in FIG. 3B, the end face 3131 is not excluded from the inner surface 34 of the battery case. No special sealing treatment is applied to the end face 3131. Although the end face 3131 is in contact with the lid portion 32, the electrolytic solution 22 can penetrate into the gap between the end face 3131 and the lid portion 32. In the battery case shown in FIG. 3B, a sealing material 36 arranged on the outer surface side of the battery case seals the side surface 321 of the lid portion 32 and the side surface of the bent portion 313. The sealing material 36 is, for example, a welding metal or the like. The sealing material 36 prevents leakage of the electrolytic solution 22 from the battery case and corrosion of the side surface 321 of the lid portion 32 due to the external environment. However, in the example shown in FIG. 3B, it is considered that there is no effect of improving the corrosion resistance of the end face 3131.

[0048] As described above, the most basic aspect of the battery case 1 according to the present embodiment has been described. Hereinafter, a more preferable aspect will be described.

[0049] (Sealing with a welding bead 13) One example of a means for assembling the lid portion 12 to the bent portion 113 is a welding bead 13 formed by laser welding, arc welding, etc. For example, as shown in Figures 2A and 2B, or Figure 4, the battery case 1 may further include a welding bead 13 that joins the lid portion 12 to the bent portion 113 of the surface treatment plate 111. In this case, it is preferable that the lid portion 12 is made of metal, the base plate 1111 is a metal plate, and the surface treatment layer 1112 is plated. The welding bead 13 can firmly join the lid portion 12 to the bent portion 113 and seal the through hole 112. For example, as shown in Figure 2A, it is preferable that the welding bead 13 surrounds the through hole 112.

[0050] When welding the lid portion 12 and the bent portion 113, the weld bead 13 may be positioned between the end face 1131 of the bent portion 113 and the inner surface 14 of the battery case 1, as shown in Figures 2A and 2B. In this case, the weld bead 13 separates the end face 1131 of the bent portion 113 from the inner surface 14 of the battery case 1. As a result, the end face 1131 at the tip of the bent portion 113 is excluded from the inner surface 14 of the battery case 1.

[0051] When welding the lid portion 12 and the bent portion 113, as shown in Figure 4, the weld bead 13 may be positioned at the tip of the bent portion 113 and cover the end face 1131. In this case as well, the end face 1131 at the tip of the bent portion 113 is excluded from the inner surface 14 of the battery case 1. Furthermore, the weld bead 13 prevents the base plate 1111 from being exposed to the outside of the battery case 1 at the end face 1131 of the bent portion 113.

[0052] (Sealing with Rivets) Another example of a means of assembling the lid portion 12 to the bent portion 113 is riveting. For example, as shown in Figures 5 and 6B, the lid portion 12 of the battery case 1 may be riveted. Since the bent portion 113 is provided on the edge of the through hole 112, the shaft of the rivet will inevitably contact the area inside the end face 1131 of the bent portion 113. The contact portion C between the shaft of the rivet and the bent portion seals the through hole 112. Also, the contact portion C between the shaft of the rivet and the bent portion will inevitably be located between the end face 1131 of the bent portion 113 and the inner surface 14 of the battery case 1. The contact portion C between the shaft of the rivet and the bent portion separates the end face 1131 of the bent portion 113 from the inner surface 14 of the battery case 1. As a result, the end face 1131 at the tip of the bent portion 113 is excluded from the inner surface 14 of the battery case 1.

[0053] The type of rivet is not particularly limited. The rivet exemplified in Figure 5 is a normal rivet having a shaft and a head. On the other hand, as exemplified in Figures 6A and 6B, the cover portion 12 may be a blind rivet. Figure 6A is a schematic cross-sectional view of the through hole 112 before the blind rivet is crimped, and Figure 6B is a schematic cross-sectional view of the through hole 112 after the blind rivet has been crimped. The specific configuration of the blind rivet can be, for example, in accordance with JIS B 0147:2004 "Blind rivets - Terms and definitions".

[0054] (Bending Angle) The bent portion 113 can be manufactured by bending the surface-treated plate 111 around the through-hole 112 toward the outside of the main body portion 11. The larger the bending angle θ, the easier it is to exclude the end face 1131 of the tip of the bent portion 113 from the inner surface 14. On the other hand, the smaller the bending angle θ, the lower the height of the bent portion 113 and the lid portion 12. This makes it easier to prevent interference between the battery 2 and other components. Also, the smaller the bending angle θ, the easier it is to manufacture the bent portion 113. An appropriate bending angle θ can be selected depending on the configuration and application of the battery case 1 and the battery 2.

[0055] In this disclosure, the term "bending angle θ" is defined as the angle between the flat portion at the tip of the bent portion 113 and the central surface of the main body portion 11 around the base end of the bent portion 113. Here, the base end of the bent portion 113 refers to the portion of the bent portion 113 that has curvature. The central surface of the main body portion 11 refers to the intermediate surface between the inner surface 14 and the outer surface 15 of the main body portion 11. A bending angle θ of 0 degrees means that the periphery of the through hole 112 is not bent at all. A bending angle θ of 180 degrees means that the periphery of the through hole 112 is completely folded back, and the tip of the bent portion 113 is parallel to the surface-treated plate 111. The bending angle θ is measured on a plane that passes through approximately the center of the through hole 112 and is perpendicular to the outer surface 15 of the main body portion 11 around the base end of the bent portion 113. The center of a through-hole is its center if the through-hole is circular, and its centroid if it is non-circular, such as an ellipse. Figures 7, 8, and 9 illustrate the bending angle θ.

[0056] An example of a configuration with a large bending angle will be explained with reference to Figures 2A and 2B. The bent portion 113 shown in Figures 2A and 2B is bent approximately 180 degrees toward the outside of the battery case 1. That is, in the battery case 1 shown in Figure 2B, the bending angle, which is the angle between the tip of the bent portion 113 and the surface treatment plate 111 around the base end of the bent portion 113, is approximately 180 degrees. As a result, as shown in Figure 2A, in a plan view along the direction perpendicular to the surface on which the through hole 112 is provided, the end face 1131 of the bent portion 113 is outside the edge of the through hole 112, and the end face 1131 and the edge of the through hole 112 are separated. As a result, the end face 1131 of the tip of the bent portion 113 can be easily and reliably excluded from the inner surface 14.

[0057] However, setting the bending angle θ to 180 degrees is not a necessary requirement for positioning the end face 1131 of the bent portion 113 outside the edge of the through hole 112, and for separating the end face 1131 from the edge of the through hole 112. To position the end face 1131 of the bent portion 113 outside the edge of the through hole 112, and for separating the end face 1131 from the edge of the through hole 112, the bending angle θ should be greater than 90 degrees. Figure 7 shows an example of a battery case 1 in which the bending angle θ is greater than 90 degrees but less than 180 degrees. The bending angle θ of the bent portion 113 shown in Figure 7 is approximately 135 degrees. Also, the end face 1131 of the bent portion 113 shown in Figure 7 is outside the edge of the through hole 112. In addition, in the battery case 1 shown in Figure 7, the surface of the lid portion 12 is tapered to match the surface of the bent portion 113. This further strengthens the sealing of the through-hole 112.

[0058] An example of a configuration with a small bending angle θ will be explained with reference to Figure 8. The bent portion 113 shown in Figure 8 is bent at approximately 45 degrees toward the outside of the battery case 1. That is, in the battery case 1 shown in Figure 2B, the bending angle θ, which is the angle between the tip of the bent portion 113 and the surface treatment plate 111 around the base end of the bent portion 113, is set to approximately 45 degrees. As a result, in a plan view along the direction perpendicular to the surface in which the through hole 112 is provided, the end face 1131 of the bent portion 113 is in contact with the edge of the through hole 112. When the bending angle is 90 degrees or less, in a plan view, the end face 1131 of the bent portion 113 is in contact with the edge of the through hole 112.

[0059] Even if the bending angle θ is less than 90 degrees, the end face 1131 at the tip of the bent portion 113 can be excluded from the inner surface 14 of the battery case 1. For example, as shown in Figure 8, the surface of the lid portion 12 is tapered to match the end face 1131 of the bent portion 113. Then, a welding bead 13 is placed on the edge of the through hole 112. As a result, the welding bead 13 is positioned between the end face 1131 of the bent portion 113 and the inner surface 14 of the battery case 1. Thus, the end face 1131 at the tip of the bent portion 113 is excluded from the inner surface 14 of the battery case 1. In the battery case 1 shown in Figure 8, the end face 1131 at the tip of the bent portion 113 can also be excluded from the inner surface 14 of the battery case 1 by using rivets for the lid portion 12.

[0060] The bending angle θ can be any value greater than 0 degrees. Preferably, the bending angle θ is 30 degrees or more, 45 degrees or more, 60 degrees or more, 90 degrees or more, or 135 degrees or more.

[0061] (Protrusion Amount P) In this disclosure, the term "protrusion amount P" is defined as the height of the bent portion 113, with respect to the outer surface 15 of the main body portion 11 around the base end of the bent portion 113. The protrusion amount P is measured along a direction perpendicular to the outer surface 15 on a plane that passes through the center of the through hole 112 and is perpendicular to the outer surface 15 of the main body portion 11 around the base end of the bent portion 113. The center of the through hole is the center of the through hole if it is circular, and the centroid if it is non-circular, such as an ellipse. Figure 9 illustrates the protrusion amount P.

[0062] In the battery case 1 according to this embodiment, preferably, the ratio P / t of the amount of protrusion P of the bent portion to the plate thickness t of the main body portion around the base end of the bent portion is 0.2 to 30. By setting P / t within this range, the cut end surface is protected, the corrosion resistance of the area around the through hole is improved, the airtightness of the through hole is improved, and the size of the battery case can be reduced and the weight reduced. P / t may be 1.0 or more, 2.0 or more, or 3.0 or more. P / t may be 25 or less, 20 or less, or 10 or less.

[0063] (Through-hole size Y) In this disclosure, the term "through-hole size Y" is defined as the size of the through-hole 112 when viewed in plan along a direction perpendicular to the outer surface 15 of the main body portion 11 around the base end of the bent portion 113. If the through-hole 112 is circular, the through-hole size Y is the diameter of the through-hole 112. If the through-hole 112 is elliptical or rounded rectangle, the through-hole size Y is the arithmetic mean of the major axis and minor axis of the through-hole 112.

[0064] When the through-hole 112 is a liquid injection port 112A, the size Y of the through-hole is preferably 0.5 to 5.0 mm. When the through-hole 112 is a cleavage valve port, the size Y of the through-hole is preferably 5.0 to 40 mm. The size Y of the through-hole may also be determined according to the thickness of the surface-treated plate 111 on which the through-hole 112 is provided. For example, the size Y of the through-hole may be set to 1 to 100 times the plate thickness t of the main body portion around the base end of the bent portion 113. By setting the size of the through-hole within the above range, the formation of the through-hole can be facilitated and the strength of the battery case can be ensured.

[0065] (Size X of the outer edge of the bent portion) In this disclosure, the term "size X of the outer edge of the bent portion" is defined as the size of the outer edge of the inner surface 14 of the battery case at the bent portion when the bent portion is viewed in plan along a direction perpendicular to the outer surface 15 of the main body portion 11 around the base end of the bent portion 113. If the outer edge of the bent portion is circular, the size X of the outer edge of the bent portion is the diameter of the outer edge of the bent portion. If the outer edge of the bent portion is elliptical or rounded rectangle, the size X of the outer edge of the bent portion is the arithmetic mean of the major axis and minor axis of the outer edge of the bent portion. However, if the bending angle θ is less than 90 degrees, as illustrated in Figure 8, the size X of the outer edge of the bent portion is considered to be equal to the size Y of the through hole.

[0066] The size X of the outer edge of the bent portion is preferably determined according to the size Y of the through hole. For example, the ratio X / Y of the size X of the outer edge of the bent portion to the size Y of the through hole is preferably 10 or less, 5 or less, or 3 or less. This makes it easy to form the bent portion.

[0067] (Types of through-holes 112) As described above, the through-holes 112 are, for example, liquid injection ports 112A or cleavage valve ports 112B. The number of through-holes 112 provided with bent portions 113 in the battery case 1 may be two or more. In this case, one through-hole 112 can be a liquid injection port 112A and another through-hole 112 can be a cleavage valve port 112B. The electrode insertion port can also be a through-hole 112 in the battery case 1 according to this embodiment.

[0068] When the through-hole is the opening of the cleavage valve and the lid is the cleavage valve, it is preferable that the cleavage valve be made of metal foil having a predetermined strength. Furthermore, it is preferable that the cleavage valve and the bent portion of the cleavage valve opening are joined by a weld bead 13. The cleavage valve ruptures when pressure exceeding a specified value is applied. It is preferable that the cleavage valve and the cleavage valve opening be welded before the contents are placed in the battery case. This makes it possible to avoid the adverse effects of spatter generated during welding.

[0069] If the through-hole is a liquid injection port, the sealing of the through-hole is performed after the contents are placed in the battery case. Therefore, if the through-hole is a liquid injection port, it is preferable to use rivets for the lid and crimp the lid to join the bent portion of the through-hole. When welding the lid to the bent portion of the liquid injection port, it is preferable to prevent the weld bead 13 from being exposed to the internal space of the battery case, as illustrated in Figure 7. This makes it possible to avoid the adverse effects of spatter generated during welding.

[0070] (Use of Ni-plated steel sheet) The surface treatment plate 111 may be a Ni-plated steel sheet. That is, the base plate 1111 may be a steel sheet and the surface treatment layer 1112 may be a Ni-plated layer. Steel sheets have high tensile strength. By using a steel sheet for the base plate 1111, the strength of the battery case 1 can be ensured while making the battery case 1 thinner and reducing its weight. By using a Ni-plated layer for the surface treatment layer 1112, the corrosion resistance of the surface treatment plate 111 can be dramatically improved.

[0071] The base steel sheet for the Ni-plated steel sheet is preferably low-carbon aluminum-killed steel, or IF steel (International Free Steel / ultra-low carbon steel). Specific examples of the chemical composition of the base steel sheet are as follows. The units for the elemental content shown below are in mass percent. (Example 1) Low-carbon aluminum-killed steel C: 0.057, Si: 0.004, Mn: 0.29, P: 0.014, S: 0.007, Al: 0.050, Cu: 0.034, Ni: 0.021, remainder: iron and impurities (Example 2) IF steel C: 0.004, Si: 0.01, Mn: 0.16, P: 0.013, S: 0.006, Al: 0.029, Cu: 0.027, Ni: 0.022, Ti: 0.013, remainder: iron and impurities (Example 3) IF steel C: 0.0012, Si: less than 0.01, Mn: 0.16, P: 0.013, S: 0.006, Al: 0.029, Cu: 0.027, Ni: 0.022, Ti: 0.020, remainder: iron and impurities

[0072] The Ni-based plating layer of a Ni-plated steel sheet may be an alloyed plating layer that is alloyed with the underlying steel sheet. In this case, the Ni-based plating layer may be a fully diffused plating layer in which the Fe of the underlying steel sheet is diffused to its surface, or it may be a partially diffused plating layer in which the Fe of the underlying steel sheet is not diffused to its surface. On the other hand, the Ni-based plating layer may not be alloyed with the underlying steel sheet.

[0073] The Ni-based plating layer is a plating layer mainly composed of Ni, optionally containing alloying elements such as Co, Fe, and W. The thickness of the Ni-based plating layer can be, for example, within the range of 0.3 μm to 3.0 μm. Furthermore, the amount of Ni deposited in the Ni-based plating layer can be, for example, 2.6 to 35.6 g / m². ２ It can be within the range of

[0074] (Thickness of surface treatment plate 111) The thickness of the flat portion of the surface treatment plate 111 near the through hole 112 is preferably 0.1 to 1.4 mm, and particularly preferably 0.3 to 1.0 mm. The vicinity of the through hole 112 may be considered as a range within 5 mm from the edge of the through hole. The thickness of the surface treatment plate 111 is the sum of the thickness of the base plate 1111 and the thickness of the surface treatment layer 1112. By making the thickness of the surface treatment plate 111 0.1 mm or more, the strength of the battery case 1 can be increased. By making the thickness of the surface treatment plate 111 1.4 mm or less, the weight of the battery case 1 can be reduced. The thickness of the surface treatment plate 111 near the through hole 112 may be 0.2 mm or more, 0.3 mm or more, or 0.5 mm or more. The thickness of the surface treatment plate 111 near the through hole 112 may be 1.2 mm or less, 1.0 mm or less, or 0.8 mm or less. Furthermore, the plate thickness t of the main body near the through-hole and around the base end of the bent portion described above can be considered the same as the thickness of the surface-treated plate 111.

[0075] (2. Method for Manufacturing Battery Case 1) A method for manufacturing a battery case 1 according to another aspect of the present disclosure comprises the steps of: forming a preliminary through hole in the surface treatment plate 111 of a main body 11 having a base plate 1111 and a surface treatment layer 1112 covering the surface of the base plate 1111; bending the surface treatment plate 111 around the preliminary through hole toward the outside of the main body 11 to form a bent portion 113 and a through hole 112; and installing a lid portion 12 on the bent portion 113 to seal the through hole 112, wherein when installing the lid portion 12 on the bent portion 113, the end face 1131 at the tip of the bent portion 113 is excluded from the inner surface 14 of the battery case 1.

[0076] The manufacturing method of the battery case 1 according to this embodiment will be described below. Naturally, the preferred embodiments of the battery case 1 described above can also be applied to the manufacturing method of the battery case 1.

[0077] (S1 Formation of preliminary through-holes) First, preliminary through-holes are formed in the main body portion 11. A preliminary through-hole is a through-hole formed before the bent portion 113 along its edge is formed. The preliminary through-hole has substantially the same configuration as a conventional through-hole in a battery case formed by a simple drilling process, as illustrated in Figure 3A.

[0078] The main body 11 is composed of at least a portion of a surface treatment plate 111. The surface treatment plate 111 has a base plate 1111 and a surface treatment layer 1112 that covers the surface of the base plate 1111. The surface treatment plate 111 is preferably a plated metal plate, and more preferably a Ni-plated steel plate.

[0079] The surface treatment plate 111 is positioned at least in the locations where the preliminary through holes are formed in the main body. In other words, the preliminary through holes are formed in the surface treatment plate 111. The thickness of the surface treatment plate 111 on which the preliminary through holes are formed is preferably, for example, 0.1 to 1.4 mm.

[0080] Pre-drilled holes are formed by drilling. The means of drilling are not particularly limited. Pre-drilled holes can be formed by various drilling methods such as drilling, punching, and laser cutting.

[0081] The diameter of the preliminary through-hole must be smaller than the diameter of the through-hole 112 in which the bent portion is formed. This is because the diameter of the through-hole 112 will be enlarged when the bent portion 113 is formed, as described later. The increase in the diameter of the through-hole 112 due to the formation of the bent portion 113 is proportional to the bending angle and the length of the bent portion 113. The length of the bent portion is the distance from the tip to the base of the bent portion, measured along the inner surface 14. The base of the bent portion is the boundary between the curvatured portion of the bent portion 113 and the flat portion of the surface-treated plate 111 around the bent portion 113, as viewed in cross-section. It is preferable to apply a diameter to the preliminary through-hole that is suitable for the planned bending angle and the length of the bent portion 113.

[0082] The surface treatment layer 1112 is substantially absent from the end faces of the pre-holes. Therefore, the corrosion resistance of the end faces of the pre-holes is low. However, in the manufacturing method of the battery case 1 according to this embodiment, it is not necessary to add an additional surface treatment layer 1112 to the end faces of the pre-holes.

[0083] (S2 Bending of surface treatment plate 111) Next, the surface treatment plate 111 around the through hole 112 is bent outwards from the main body 11. This forms the bent portion 113 and the through hole 112. The through hole 112 is preferably, for example, an injection port 112A or a cleavage valve port 112B.

[0084] The means for forming the bent portion 113 are not particularly limited. Preferably, the bent portion 113 can be manufactured by first burring the edge of the pre-through hole to form a cylindrical projection, and then flaring the projection to widen the tip of the projection.

[0085] The bending conditions are not particularly limited. Bending conditions include, for example, the bending angle when forming the bent portion 113 and the length of the bent portion 113. Suitable bending conditions are exemplified below. Specific examples of bending conditions are exemplified below. When the through hole is an injection port with a diameter of approximately 5.0 mm and the thickness of the surface-treated plate in which the through hole is provided is 0.8 mm, it is preferable to perform the ironing burring and flaring processes under the following conditions: - Diameter of the preliminary through hole: approximately 1.0 mm - Outer diameter of the punch for ironing burring: approximately 5.0 mm - Inner diameter of the die for ironing burring: approximately 5.8 mm - Apex angle of the tip of the punch for flaring: approximately 170 degrees - Shape of the die for flaring: flat When the through hole is an opening valve port with a diameter of 10 mm and the thickness of the surface-treated plate in which the through hole is provided is 0.8 mm, it is preferable to perform the ironing burring and flaring processes under the following conditions.・Diameter of the pre-punched hole: Approximately 5.0 mm ・Outer diameter of the punch for burring: Approximately 10.0 mm ・Inner diameter of the die for burring: Approximately 11.6 mm ・Angle of the tip of the punch for flaring: Approximately 170 degrees ・Shape of the die for flaring: Flat When the pre-punched hole is made into a 10 mm diameter cleavage valve opening and the thickness of the surface-treated plate in which the pre-punched hole is made is 0.8 mm, ironing burring and flaring may be performed under the following conditions: ・Diameter of the pre-punched hole: Approximately 5.0 mm ・Outer diameter of the punch for burring: Approximately 10.0 mm ・Inner diameter of the die for ironing burring: Approximately 10.8 mm ・Angle of the tip of the punch for flaring: Approximately 170 degrees ・Shape of the die for flaring: Flat The various values ​​mentioned above are merely examples of suitable values. For example, the above values ​​can be appropriately changed within a range of ±0.5 mm.

[0086] The ratio P / t of the protrusion amount P of the bent portion, which is the height of the bent portion relative to the outer surface of the main body around the base end of the bent portion, and the plate thickness t of the main body around the base end may be set to 0.2 to 30. The larger the protrusion amount, the easier it is to exclude the end face 1131 of the bent portion 113 from the inner surface 14 of the battery case 1. On the other hand, the smaller the protrusion amount, the easier it is to avoid interference between the battery case 1 and other components.

[0087] Furthermore, when bending the surface-treated plate 111, the end face 1131 of the bent portion 113 may be positioned outside the edge of the through-hole 112 in a plan view along a direction perpendicular to the surface on which the through-hole 112 is provided. This allows for the manufacture of a battery case 1 having the configuration illustrated in Figures 2A and 2B.

[0088] (S3 Sealing of through hole 112) After the bent portion 113 is formed, the cover portion 12 is installed on the bent portion 113 to seal the through hole 112. When installing the cover portion 12 on the bent portion 113, the end face 1131 of the tip of the bent portion 113 is excluded from the inner surface 14 of the battery case 1.

[0089] The means for sealing the through-hole 112 are not particularly limited. One example of a sealing means is welding. The through-hole 112 can be sealed by welding the lid portion 12 to the bent portion 113. The welding can be, for example, laser welding, arc welding, or electron beam welding. For example, as shown in Figure 2A, it is preferable to employ a welding method that can form a weld bead 13 that surrounds the through-hole 112. When welding the lid portion 12 to the bent portion 113, it is preferable to make the lid portion 12 out of metal, the base plate 1111 out of metal, and the surface treatment layer 1112 out of plating. Also, as illustrated in Figures 7 and 8, it is preferable to select a shape for the lid portion 12 that matches the shape of the bent portion 113.

[0090] Another example of a means for sealing the through-hole 112 is riveting. That is, the lid portion 12 may be made of rivets. In this case, the through-hole 112 can also be sealed by riveting and crimping of the bent portion 113. It is preferable that the rivet has a shape that matches the shape of the bent portion 113.

[0091] The means for excluding the end face 1131 at the tip of the bent portion 113 from the inner surface 14 of the battery case 1 are not particularly limited. If the sealing means is welding, the end face 1131 at the tip of the bent portion 113 can be excluded from the inner surface 14 of the battery case 1 by selecting a welding position according to the shape of the bent portion 113. As illustrated in Figure 2B, etc., a welding bead 13 may be placed between the end face 1131 and the inner surface 14 of the battery case 1. Alternatively, welding of the end face 1131 may be performed, and as illustrated in Figure 4, the welding bead 13 may be placed at the tip of the bent portion 113 so as to cover the end face 1131.

[0092] If the sealing means is riveting, there is a bent portion 113 that protrudes outward from the main body 11, so the end face 1131 of the tip of the bent portion 113 is inevitably excluded from the inner surface 14 of the battery case 1.

[0093] The basic aspects of the manufacturing method of the battery case 1 according to this embodiment have been described above. However, it should be noted that the manufacturing method of the battery case 1 according to this embodiment may have various additional steps. For example, if the battery case 1 has a top plate 11A, a side plate 11B, and a bottom plate 11C as illustrated in Figure 1, the manufacturing method of the battery case 1 according to this embodiment may further include a step of joining the top plate 11A, the side plate 11B, and the bottom plate 11C to each other.

[0094] Furthermore, it should be noted that in the actual manufacture of the battery 2, the assembly of the battery case 1 and the installation of battery components into the battery case 1 may be carried out in parallel. For example, if the through-hole 112 is the electrolyte injection port 112A, the electrolyte 22 can be injected into the battery case 1 through the through-hole 112 and then the through-hole 112 can be sealed. For example, if the battery case 1 has a top plate 11A, a side plate 11B, and a bottom plate 11C as illustrated in Figure 1, the side plate 11B and the bottom plate 11C can be joined first, then various components such as electrodes can be installed inside the battery case 1, and then the top plate 11A and the side plate 11B can be joined. If the battery case 1 is a neutral can, the steps of forming an electrode insertion port in the battery case 1 and assembling insulating material into the electrode insertion port can be added to the manufacturing method of the battery case 1 according to this embodiment. The insulating material electrically insulates the electrode 21 from the battery case 1. The steps necessary for the manufacture of the battery 2 can be appropriately added to the manufacturing method of the battery case 1 according to this embodiment.

[0095] (3. Battery) A battery 2 according to another embodiment of the present disclosure comprises a battery case 1 according to this embodiment. A more specific example of the battery 2 according to this embodiment comprises a battery case 1 according to this embodiment, an electrode body and electrolyte 22 housed in the battery case 1, and an electrode 21 electrically connected to the electrode body, wherein the through hole 112 of the battery case 1 is an electrolyte inlet 112A and / or a cleavage valve inlet 112B, and the lid of the through hole 112 of the battery case 1 is an electrolyte plug 12A that seals the electrolyte inlet 112A and / or a cleavage valve 12B that seals the cleavage valve inlet 112B. The battery 2 according to this embodiment has excellent corrosion resistance in the through hole 112.

[0096] The battery 2 according to this embodiment may be a battery cell. A battery cell is the smallest unit of a battery in a battery module. A battery module is constructed by electrically connecting multiple battery cells. Multiple battery modules can be further electrically connected to form a battery pack. A battery pack can also be constructed by electrically connecting a large number of battery cells without constructing a battery module. A battery module or battery pack can be used, for example, as a power source for an electric vehicle. However, it is not essential to use a battery module or battery pack in an electric vehicle. It is also possible to mount a large number of battery cells in an electric vehicle without constructing a module or pack.

[0097] In the battery 2 according to this embodiment, the battery case 1 is preferably a neutral case. A neutral case is a battery case 1 that is electrically insulated from the electrodes 21 of the battery 2, i.e., the positive electrode and the negative electrode.

[0098] The neutral can is electrically neutral. Therefore, the neutral can is susceptible to corrosion by the electrolyte 22. However, in the battery case 1 according to this embodiment, the base plate 1111 is protected by the surface treatment layer 1112. Furthermore, the end face 1131 of the bent portion 113, which is not protected by the surface treatment layer 1112, is excluded from the inner surface 14 of the battery case 1 and does not come into contact with the electrolyte 22. Therefore, the battery case 1 according to this embodiment exhibits high corrosion resistance even when it is a neutral can. The battery case 1 with a neutral can is suitably used, for example, as an exterior material for the battery 2 of an electric vehicle.

[0099] 1 Battery case 11 Main body 11A Top plate 11B Side plate 11C Bottom plate 111 Surface treatment plate 1111 Base plate 1112 Surface treatment layer 112 Through hole 112A Liquid injection port 112B Opening valve port 113 Bent part 1131 End face 12 Lid part 12A Liquid injection plug 12B Opening valve 13 Welding bead 14 Inner surface 15 Outer surface 2 Battery 21 Electrode 22 Electrolyte 311 Surface treatment plate 3111 Base plate 3112 Surface treatment layer 312 Through hole 3131 End face 32 Lid part 33 Welding bead 34 Inner surface 36 Sealing material C Contact area between rivet shaft and bent part θ Bending angle P Protrusion amount X Size of the outer edge of the bent section Y Size of the through hole

Claims

1. A battery case comprising: a main body portion having a through-hole; and a lid portion sealing the through-hole, wherein at least a part of the main body portion is composed of a surface-treated plate having a base plate and a surface-treated layer covering the surface of the base plate; the through-hole is provided in the surface-treated plate; the surface-treated plate is provided along the edge of the through-hole and has a bent portion that protrudes toward the outside of the battery case; and the end face of the tip of the bent portion is excluded from the inner surface of the battery case.

2. The battery case according to claim 1, wherein the lid is made of metal, the base plate is a metal plate, the surface treatment layer is plated, and the battery case further comprises a weld bead that joins the lid and the bent portion of the surface treatment plate, and the weld bead is disposed between the end face of the bent portion and the inner surface of the battery case.

3. The battery case according to claim 1, wherein the lid is made of metal, the base plate is a metal plate, the surface treatment layer is plated, and the battery case further comprises a welding bead that joins the lid and the bent portion of the surface treatment plate, the welding bead is positioned at the tip of the bent portion and covers the end face.

4. The battery case according to claim 1, wherein the lid is a rivet.

5. The battery case according to any one of claims 1 to 4, wherein the end face of the bent portion is located outside the edge of the through hole and spaced apart from the edge of the through hole in a plan view along a direction perpendicular to the surface on which the through hole is provided.

6. The battery case according to any one of claims 1 to 4, wherein the ratio P / t of the protrusion amount P of the bent portion, which is the height of the bent portion with respect to the outer surface of the main body portion around the base end of the bent portion, to the plate thickness t of the main body portion around the base end is 0.2 to 30.

7. The battery case according to any one of claims 1 to 4, wherein the through hole is a liquid injection port or a cleavage valve port.

8. The battery case according to any one of claims 1 to 4, wherein the base plate is a steel plate and the surface treatment layer is a Ni-based plating layer.

9. The battery case according to any one of claims 1 to 4, wherein the thickness of the surface-treated plate in which the through-hole is formed is 0.1 to 1.4 mm.

10. A method for manufacturing a battery case, comprising the steps of: forming a preliminary through-hole in a surface treatment plate having a base plate and a surface treatment layer covering the surface of the base plate; bending the surface treatment plate around the preliminary through-hole toward the outside of the main body to form a bent portion and a through-hole; and installing a cover portion on the bent portion to seal the through-hole, wherein when installing the cover portion on the bent portion, the end face of the tip of the bent portion is excluded from the inner surface of the battery case.

11. The method for manufacturing a battery case according to claim 10, wherein the lid portion is made of metal, the base plate is made of metal, the surface treatment layer is plated, and when installing the lid portion on the bent portion, the lid portion is welded to the bent portion, and the weld bead is placed between the end face and the inner surface of the battery case.

12. The method for manufacturing a battery case according to claim 10, wherein the lid portion is made of metal, the base plate is made of metal, the surface treatment layer is plated, and when installing the lid portion on the bent portion, the lid portion is welded to the bent portion, and the weld bead is placed on the tip of the bent portion so as to cover the end face.

13. The method for manufacturing a battery case according to claim 10, wherein the lid portion is riveted.

14. A method for manufacturing a battery case according to any one of claims 10 to 13, wherein the ratio P / t of the amount of protrusion P of the bent portion, which is the height of the bent portion with respect to the outer surface of the main body portion around the base end of the bent portion, and the plate thickness t of the main body portion around the base end is 0.2 to 30.

15. A method for manufacturing a battery case according to any one of claims 10 to 13, wherein when bending the surface-treated plate, the end face of the bent portion is positioned outside the edge of the through-hole and separated from the edge of the through-hole in a plan view along a direction perpendicular to the surface on which the through-hole is provided.

16. The method for manufacturing a battery case according to any one of claims 10 to 13, wherein the through hole is used as a liquid injection port or a slitting valve port.

17. A method for manufacturing a battery case according to any one of claims 10 to 13, wherein the base plate is a steel plate and the surface treatment layer is a Ni-based plating layer.

18. A method for manufacturing a battery case according to any one of claims 10 to 13, wherein the thickness of the surface-treated plate near the through-hole is 0.1 to 1.4 mm.

19. A battery comprising the battery case described in any one of claims 1 to 4.

20. The battery according to claim 19, wherein the battery case is electrically insulated from the electrodes.

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