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

Abstract

The present invention provides a battery case with suppressed thermal deformation, a battery, and a method for manufacturing a battery case. [Solution] A battery case according to one aspect of the present disclosure comprises a cylindrical body made of a bent metal plate and a pair of lids that seal the openings at both ends of the body, wherein the body has at least a pair of overlapping flanges that extend from one lid to the other lid and are provided at the ends of the metal plate, the flanges are positioned on the outer surface of the battery case, the body has a weld metal that extends from one lid to the other lid and joins the overlapping flanges to each other, the flanges have a bent portion that bends the flange toward the outer surface of the battery case along from one lid to the other lid, the weld metal is positioned closer to the tip of the flange than the bent portion of the flange, and the weld metal is spaced away from the bent portion.

Description

Technical Field

[0001] The present disclosure relates to a battery case, a battery, and a method for manufacturing a battery case.

Background Art

[0002] In order to ensure the driving range of an electric vehicle, it is necessary to mount a large number of secondary batteries on the electric vehicle. A general secondary battery is installed such that the electrode terminals are arranged upward. Such a battery is referred to as an upper-terminal type battery. However, when a plurality of upper-terminal type batteries are arranged in the floor portion of an electric vehicle, the thickness of the floor portion increases. As a result, the floor surface of the electric vehicle becomes higher, and it may be difficult for passengers to board the electric vehicle.

[0003] Due to the above circumstances, a side-terminal type battery may be adopted as the secondary battery for an electric vehicle. A side-terminal type battery is a battery in which the electrode terminals are arranged horizontally. An example of a side-terminal type battery is a long-plate-shaped rectangular battery such as a blade battery. A rectangular battery means a battery in which the shape of the exterior material is substantially a rectangular parallelepiped.

[0004] In the present disclosure, a blade battery means a long-plate-shaped rectangular battery including an exterior material having a cylindrical body and a pair of lid bodies that seal the openings at both ends thereof, and electrodes are provided on the lid bodies. Hereinafter, for the sake of convenience of explanation, the direction from one lid body of the blade battery to the other lid body is referred to as the longitudinal direction, the direction perpendicular to the longitudinal direction and parallel to the long side of the lid body is referred to as the width direction, and the direction perpendicular to the longitudinal direction and the width direction is referred to as the thickness direction. The blade battery has a length in the longitudinal direction that is extremely long with respect to the width direction, and a length in the thickness direction that is extremely short with respect to the width direction.

[0005] The cover of a blade battery mounted on an electric vehicle, where the terminals are located, is oriented laterally. For this reason, blade batteries are called lateral terminal batteries. The longitudinal direction of a blade battery mounted on an electric vehicle often coincides with the vehicle's width, and the width often coincides with the vehicle's height. In this case, the dimensions along the longitudinal direction of the blade battery correspond to the vehicle's width, and the dimensions along the width correspond to the thickness of the vehicle's floor.

[0006] The longitudinal dimension of a blade battery, i.e., the distance between a pair of covers, can exceed 900 mm. Manufacturing such a long body by deep drawing is difficult. Therefore, the body of a battery case for a rectangular battery with horizontal terminals is usually manufactured by bending a metal sheet into a cylindrical shape and joining its ends. Examples of joining methods include seam welding and butt laser welding. Methods for joining the ends of metal sheets are disclosed, for example, in Patent Documents 1 and 2. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 59-179284 [Patent Document 2] Japanese Patent Application Publication No. 7-309138 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] To ensure optimal performance of a rechargeable battery, it is necessary to maintain it within an appropriate temperature range. For example, a suitable temperature range for rechargeable batteries used in electric vehicles is 5 to 45°C. If the temperature of the rechargeable battery is too low, its internal resistance may increase, potentially reducing its capacity. Conversely, if the temperature is too high, the battery may deteriorate more rapidly.

[0009] Therefore, electric vehicles are equipped with a cooling mechanism for secondary batteries. One example of a cooling method is to place the battery 2 on a cooling plate 3 through which a refrigerant is circulated, as shown in Figure 11A. Another example of a cooling method is to place the cooling plate 3 between the batteries 2 arranged in a row, as shown in Figure 11B.

[0010] In addition, a filler 4 may be placed in the gap between the battery 2 and the cooling plate 3. The filler 4 is a resin-based material called a thermal conductive resin or gap filler. The filler 4 reduces the thermal resistance between the battery 2 and the cooling plate 3, thereby promoting the cooling of the battery 2.

[0011] If the gap between the battery 2 and the cooling plate 3 is large, the cooling performance of the cooling plate 3 will decrease, or the amount of filler 4 used will increase. An increase in the amount of filler 4 used will lead to an increase in vehicle weight and an increase in vehicle manufacturing costs.

[0012] A battery with horizontal terminals has a large length along the vehicle width direction W. The inventors focused on the fact that thermal deformation perpendicular to the vehicle width direction W is likely to occur during welding of the body.

[0013] In view of the above-mentioned problems, this disclosure aims to provide a battery case in which thermal deformation is suppressed, a battery, and a method for manufacturing a battery case. [Means for solving the problem]

[0014] The gist of this disclosure is as follows:

[0015] (1) A battery case according to one aspect of the present disclosure comprises a cylindrical body made of a bent metal plate and a pair of lids sealing openings at both ends of the body, wherein the body has at least a pair of overlapping flanges extending from one lid to the other lid and provided at the ends of the metal plate, the flanges are positioned on the outer surface of the battery case, the body has a weld metal extending from one lid to the other lid and joining the overlapping flanges to each other, the flanges have a bent portion that bends the flange toward the outer surface of the battery case, along one lid to the other lid, the weld metal is positioned closer to the tip of the flange than the bent portion of the flange, and the weld metal is spaced apart from the bent portion. (2) Preferably, in the battery case described in (1) above, the bent portion bends the flange so that it is aligned with the outer surface of the battery case. (3) Preferably, in the battery case described in (1) or (2) above, the thickness of the metal plate is 0.1 to 1.4 mm. (4) Preferably, in the battery case described in any one of the above items (1) to (3), the metal plate is a base steel plate and a nickel-plated steel plate having a nickel-plated layer provided on the surface of the base steel plate. (5) Preferably, in the battery case described in (4) above, the thickness of the Ni-based plating layer is 0.1 to 10 μm. (6) Preferably, in the battery case described in any one of the above items (1) to (5), the weld metal is seam weld metal or laser weld metal. (7) Preferably, in the battery case described in any one of the above items (1) to (6), the joint between the lid and the body is a crimped portion or laser-welded metal. (8) Preferably, in the battery case described in any one of the above items (1) to (7), the lid is made of Ni-plated steel sheet or stainless steel sheet. (9) Preferably, in the battery case described in any one of the above items (1) to (8), the distance between the pair of lids is 1.5 times or more the length of the long side of the lid. (10) Preferably, in the battery case described in any one of the above items (1) to (9), the weld metal is positioned at the tip of the flange.

[0016] (11) A battery according to another aspect of the present disclosure comprises a battery case as described in any one of paragraphs (1) to (10) above. (12) Preferably, in the battery described in (11) above, the battery case is electrically insulated from the electrodes.

[0017] (13) A method for manufacturing a battery case according to another aspect of the present disclosure is a method for manufacturing a battery case according to any one of (1) to (10) above, comprising the steps of: providing flanges at both ends of a metal plate; bending the metal plate so that the flanges overlap each other on the outer surface of the battery case to form a cylindrical body; welding the overlapping pair of flanges to form a body; bending the flanges toward the outer surface of the battery case to form a bent portion; and joining a lid to the openings at both ends of the body, wherein the bent portion is positioned closer to the base end of the flange than the weld metal, and the bent portion is separated from the weld metal. (14) Preferably, in the method for manufacturing a battery case described in (13) above, the cylindrical body is rectangular. (15) Preferably, in the method for manufacturing a battery case described in (13) above, the cylindrical body is cylindrical, and the manufacturing method further comprises a step of deforming the cylindrical body into a rectangular tubular shape before joining the lid to the openings at both ends of the body. (16) Preferably, in the method for manufacturing a battery case described in any one of the above items (13) to (15), the flange is seam-welded. (17) Preferably, in the method for manufacturing a battery case described in any one of the above items (13) to (15), the flange is laser-welded. [Effects of the Invention]

[0018] According to this disclosure, it is possible to provide a battery case in which thermal deformation is suppressed, a battery, and a method for manufacturing a battery case.

Brief Description of the Drawings

[0019] [Figure 1] This is a perspective view of the battery case according to this embodiment. [Figure 2] This is a cross-sectional view taken along line II-II of the flange provided on the body of the battery case of FIG. 1. [Figure 3] This is a cross-sectional view of the flange manufactured by laser welding. [Figure 4] This is a cross-sectional view of the flange manufactured by end welding. [Figure 5] This is a cross-sectional view of the butt laser welding portion of the body of a conventional battery case. [Figure 6] This is a cross-sectional view of the seam welding portion of the body of a conventional battery case. [Figure 7] This is a cross-sectional view for explaining a method of specifying the position of the bending portion. [Figure 8] This is a schematic view of the process of providing flanges at both ends of a metal plate. [Figure 9A] This is a schematic view of the process of bending a metal plate into a square tube shape. [Figure 9B] This is a schematic view of the process of bending a metal plate into a cylindrical shape. [Figure 9C] This is a schematic view of the process of forming a cylindrical body from two metal plates. [Figure 10A] This is a schematic view of the process of seam welding the flanges. [Figure 10B] This is a schematic view of the process of seam welding the flanges. [Figure 11A] This is a schematic view of a battery equipped with a cooling mechanism. [Figure 11B] This is a schematic view of a battery equipped with a cooling mechanism.

Modes for Carrying Out the Invention

[0020] 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. Furthermore, dimensions and other specifications in the drawings are not strictly illustrated.

[0021] (1. Battery case 1) The battery case 1 according to this embodiment is an exterior material for a battery 2 (see Figures 11A and 11B). 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.

[0022] In recent electric vehicles, long, plate-shaped batteries with horizontal terminals, such as blade batteries, are sometimes used. Multiple horizontal-terminal batteries (batteries 2) mounted on an electric vehicle are stacked in the thickness direction with their longitudinal direction oriented in the width direction W of the electric vehicle, as illustrated in Figures 11A and 11B. The battery case 1 according to this disclosure can be suitably used as an exterior material for horizontal-terminal batteries.

[0023] The battery case 1 according to this embodiment comprises a cylindrical body 11 made of a bent metal plate 11S, and a pair of lids 12 that seal the openings at both ends of the body 11, wherein the body 11 has at least a pair of overlapping flanges 1112 that extend from one lid 12 to the other lid 12 and are provided at the ends of the metal plate 11S, the flanges 1112 are arranged on the outer surface 14 of the battery case 1, and the body 11 extends from one lid 12 to the other lid 12 Furthermore, the overlapping flanges 1112 have a weld metal (for example, seam weld metal 1111S or laser weld metal 1111L) that joins them to each other, and the flange 1112 has a bent portion 1113 that bends the flange 1112 toward the outer surface 14 of the battery case 1, along from one cover 12 to the other cover 12, and the weld metal is positioned closer to the tip of the flange 1112 than the bent portion 1113 of the flange 1112, and the weld metal is spaced apart from the bent portion 1113.

[0024] Figure 1 shows a perspective view of an example of the battery case 1 according to this embodiment. Figure 2 shows a cross-sectional view of the battery case 1 of Figure 1 along line II-II. Figure 2 is an enlarged cross-sectional view of the flange 1112 provided on the body 11. Figure 3 is an enlarged cross-sectional view illustrating another aspect of the flange 1112. Hereinafter, the details of the battery case 1 according to this embodiment will be described with reference to Figures 1, 2 and 3, etc.

[0025] (Body 11 and lid 12) The battery case 1 has a body 11 and a lid 12. The body 11 and the lid 12 are joined together to form a sealed can.

[0026] The body 11 has a hollow, elongated structure with openings at both ends. That is, the body 11 is cylindrical and has openings at both ends in the longitudinal direction. The term "cylindrical" includes both cylindrical and rectangular shapes. When the battery case 1 is used as an exterior material for a battery in an electric vehicle, it is preferable that the body 11 be rectangular.

[0027] The openings at both ends of the body 11 are sealed by a pair of plate-shaped covers 12. The ends of the body 11 and the ends of the covers 12 are joined by any means. Examples of means for joining the body 11 and the covers 12 are crimping and laser welding. In this embodiment of the battery case 1, the weld metal that joins the body 11 and the covers 12 is referred to as the second weld metal 13.

[0028] The cylindrical body 11 is made from a bent metal plate. From the viewpoint of simplifying the manufacturing process, it is preferable that the body 11 be made from a single metal plate, as shown in Figure 1. On the other hand, the cylindrical body 11 can also be made from two or more metal plates. For example, the body 11 can be formed by joining two or more metal plates and bending them into a cylindrical shape. Alternatively, the body 11 can be manufactured by joining two or more bent metal plates to form a cylindrical body.

[0029] Figure 9C shows a schematic diagram of the process of manufacturing the fuselage 11 by joining two bent metal plates. In the example shown in Figure 9C, two metal plates bent into a U shape are overlapped at their ends to form a cylindrical body. By joining the two overlapping portions in the example shown in Figure 9C, a fuselage 11 having two joint portions 111 is obtained. When the cylindrical fuselage 11 is made from two or more metal plates, it is preferable that both of the two joint portions 111 have flanges 1112, which will be described later.

[0030] (Flange 1112) A bent metal plate is formed into a cylindrical shape by joining its ends. In the battery case 1 according to this embodiment, flanges 1112 are provided at both ends of the metal plate. A pair of flanges 1112 are welded together in an overlapping state. The overlapping pair of flanges 1112 and the weld metal joining them constitute a lap joint.

[0031] In this embodiment of the battery case 1, the weld metal joining the flange 1112 is referred to as the first weld metal. The first weld metal is distinct from the second weld metal 13 that joins the lid 12 and the body 11 as described above. Hereinafter, the term "weld metal" means "first weld metal." Hereinafter, the term "joint 111" means the overlap joint formed by the first weld metal and the flange 1112 to which the first weld metal is provided.

[0032] Both of the pair of overlapping flanges 1112 are positioned on the outer surface 14 of the battery case 1. For example, as shown in Figures 2 and 3, at the joint 111, the surfaces of the two flanges 1112 facing the inner surface 15 of the battery case 1 are in contact with each other. As a result, both of the pair of overlapping flanges 1112 are positioned on the outer surface 14 of the battery case 1.

[0033] Here, the conventional joint 611 of a battery case will be described with reference to Figures 5 and 6. Figure 5 is a cross-sectional view of the butt-joint laser-welded joint of the body of a conventional battery case. In the joint 611 illustrated in the cross-sectional view of Figure 5, the end faces of a pair of ends 6112 of metal plates are butted together and joined by laser welding metal 6111L. Figure 6 is a cross-sectional view of the seam-welded joint of the body of a conventional battery case. In the joint 611 illustrated in Figure 6, a pair of ends 6112 of metal plates are overlapped and joined by seam welding metal 6111S. Neither the conventional joint 611 in Figure 5 nor the conventional joint 611 in Figure 6 is provided with a flange 1112.

[0034] The joint 111 functions as a seam in the cylindrical body 11. Therefore, the flange 1112 constituting the joint 111 extends from one opening to the other opening of the cylindrical body 11. As described above, the opening of the body 11 is provided with a cover 12 to seal it. Therefore, the flange 1112 extends from one cover 12 to the other cover 12.

[0035] As illustrated in Figure 1, when the fuselage 11 is made from a single metal plate, there is one joint 111 provided on the fuselage 11. On the other hand, when the fuselage 11 is made from two or more metal plates, the fuselage 11 may be provided with two or more joints 111. In this case, the fuselage 11 will have two or more pairs of overlapping flanges 1112. For example, as illustrated in Figure 9C, a fuselage 11 having two joints 111 can be obtained by joining two U-shaped metal plates.

[0036] (Weld metal (first weld metal)) The body 11 has a first weld metal that joins two overlapping flanges 1112 to each other. The weld metal is formed along the extending direction of the flanges 1112. Thus, the first weld metal extends from one cover 12 to the other cover 12, similar to the flanges 1112.

[0037] An example of the first weld metal is the seam weld metal 1111S illustrated in Figure 2. The seam weld metal 1111S is formed by seam welding. Seam welding is a type of resistance welding in which pressure and current are applied to the base metal using a disc electrode, and the welding is performed continuously along the joint while rotating the electrode (see JIS Z 3001-6:2013 "Welding terminology - Part 6: Resistance welding").

[0038] The seam weld metal 1111S is formed inside the lap joint, as schematically shown in the cross-sectional view of Figure 2. The seam weld metal 1111S cannot be seen from the outside of the flange 1112 joined by seam welding. However, indentations 1111i are formed where the seam weld metal 1111S is provided. Indentations 1111i are depressions on the surface of the base material caused by the disc electrode as a result of welding in lap resistance welding (see JIS Z 3001-6:2013 "Welding Terminology - Part 6: Resistance Welding"). The indentations 1111i formed on the surface of the flange 1112 are easily visible.

[0039] Another example of the first weld metal is the laser weld metal 1111L illustrated in Figure 3. The laser weld metal 1111L is formed by laser welding. Laser welding is a welding method that uses laser light as the energy medium (see JIS Z 3001-5:2013 "Welding Terminology - Part 5: Laser Welding"). Figure 3 shows a schematic cross-sectional view of a flange 1112 joined by laser welding. The laser weld metal 1111L is visible on the surface of at least one flange 1112.

[0040] (Bent section 1113) As shown in the cross-sectional views of Figures 2 and 3, the flange 1112 is inclined with respect to the vertical direction V of the outer surface 14 on which the flange 1112 is provided. That is, the flange 1112 has a bent portion 1113 that bends the flange 1112 toward the outer surface 14 of the battery case 1. The bent portion 1113 is provided along the entire length of the flange 1112. That is, the bent portion 1113 is provided along one cover 12 to the other cover 12.

[0041] The angle θ formed by the mating surfaces S of the pair of flanges 1112 with respect to the vertical direction V is any value greater than 0 degrees. Preferably, the flanges 1112 are bent to conform to the outer surface 14 of the battery case 1, as shown in Figures 2 and 3. The state in which the flanges 1112 conform to the outer surface 14 of the battery case 1 means that the mating surface S of the flanges 1112 and the outer surface 14 of the battery case 1 are substantially parallel. When the flanges 1112 conform to the outer surface 14 of the battery case 1, the angle θ formed by the mating surfaces S of the flanges 1112 with respect to the vertical direction V is approximately 80 to 90 degrees. More preferably, one of the pair of flanges 1112 constituting the joint 111 is in contact with the outer surface 14 of the battery case 1.

[0042] In the cross-sectional views of Figures 2 and 3, there is one bent portion 1113 on the flange 1112, but there may be two or more. For example, a first bent portion may be provided at the base of the flange 1112, and a second bent portion may be provided between the first weld metal and the first bent portion. In this case, the angle θ formed by the mating surfaces S of the pair of flanges 1112 with respect to the vertical direction V is the sum of the bending angle at the first bent portion and the bending angle at the second bent portion. The angle θ formed by the mating surfaces S of the pair of flanges 1112 is the angle formed by the mating surfaces near the tip of the flange 1112.

[0043] The first weld metal is positioned closer to the tip of the flange 1112 than the bent portion 1113 of the flange 1112. In other words, the bent portion 1113 of the flange 1112 is closer to the base end of the flange 1112 than the first weld metal. Furthermore, the first weld metal is spaced apart from the bent portion 1113.

[0044] Whether or not a flange 1112 has a bent portion 1113 is determined by the following procedure. First, the cross-section of the joint 111 is observed. The cross-section is perpendicular to the longitudinal direction of the body. The cross-section of the joint 111 is etched by known means to make the central segregation line of the metal plate and the weld metal easier to see. Then, the shape of the base of the flange 1112 is observed. If at least one of the two flanges 1112 included in the joint 111 has a portion that is bent in the opposite direction to when the flange 1112 was formed, that portion is determined to be a bent portion 1113.

[0045] The bent portion 1113 will be described in detail below with reference to the cross-sectional view of the seam weld in Figure 7. Both the metal plate 11S on the left side of the page and the metal plate 11S on the right side of the page in Figure 7 are subjected to two bending processes. The first bending process is for forming the flange 1112. The metal plate 11S on the left side of the page is bent in a counterclockwise direction (CCW direction) during the first bending process. The metal plate 11S on the right side of the page is bent in a clockwise direction (CW direction) during the first bending process. A first plastic deformation portion α is created at the base of the flange 1112 provided on these metal plates 11S. The second bending process is for bending the flange 1112 toward the outer surface 14 of the battery case to form the bent portion 1113. Both the metal plate 11S on the left side of the page and the metal plate 11S on the right side of the page are bent in a counterclockwise direction during the second bending process. A second plastic deformation portion β is formed between the base of the flange 1112 provided on these metal plates 11S and the seam weld metal 1111S.

[0046] In the same flange 1112, if the bending direction of the first plastically deformed portion α differs from the bending direction of the second plastically deformed portion β, the second plastically deformed portion β is determined to be a bent portion 1113. In the cross-sectional view of Figure 7, in the flange 1112 of the metal plate 11S on the right side of the page, the bending direction of the first plastically deformed portion α is clockwise (CW direction), and the bending direction of the second plastically deformed portion β is counterclockwise (CCW direction). Since the two are different, the second plastically deformed portion β in the flange 1112 of the metal plate 11S on the right side of the page is determined to be a bent portion 1113. If the first weld metal is positioned closer to the tip of the flange than the second plastically deformed portion β which has been determined to be a bent portion 1113, the weld metal is considered to be positioned closer to the tip of the flange than the bent portion of the flange.

[0047] Furthermore, in the cross-sectional observation described above, if the pair of flanges 1112 do not protrude from the area within 5t of the outer surface 14 of the battery case 1, the bent portion 1113 is considered to bend the flanges 1112 so that they lie along the outer surface 14 of the battery case 1. t is the thickness of the metal plate 11S. In the cross-sectional view of Figure 7, the area below the dashed line drawn horizontally on the paper is the area within 5t of the outer surface 14 of the battery case 1. The flanges 1112 do not protrude from this area. Therefore, the bent portion 1113 shown in the cross-sectional view of Figure 7 bends the flanges 1112 so that they lie along the outer surface 14 of the battery case 1.

[0048] Furthermore, if the distance G between the apex of the bent portion 1113 and the first weld metal, measured along the outer surface 14, is 0.8 times or more the thickness of one flange 1112, the first weld metal is considered to be separated from the bent portion. The apex of the bent portion 1113 is the point of the second plastically deformed portion β that is furthest from the outer surface 14. The surface of the flange 1112 near the second plastically deformed portion β is curved. The boundary between the curved portion and the straight portion of the flange surface corresponds to the apex of the bent portion 1113. Preferably, the distance G between the apex of the bent portion 1113 and the first weld metal, measured along the outer surface 14, is 1.0 times or more, 1.5 times or more, or 2.0 times or more the thickness of one flange 1112.

[0049] (Effects and Benefits) Figures 5 and 6 show schematic cross-sectional views of a joint 111 provided on the body 11 of a conventional battery case 1. The joint 111 in Figure 5 is formed by seam welding. The joint 111 in Figure 6 is formed by laser welding. Joints 111 as shown in Figures 5 and 6 are easy to manufacture. Furthermore, joints 111 as shown in Figures 5 and 6 can flatten the outer surface 14 of the battery case 1. Therefore, these joints 111 are widely used in conventional battery cases 1.

[0050] However, the inventors have found that conventional battery cases 1 are prone to thermal deformation. In particular, when the battery case is a blade battery with a large size that conforms to the body 11, the amount of thermal strain in the direction perpendicular to the longitudinal direction of the body 11 is large.

[0051] On the other hand, in the battery case 1 according to this embodiment, the flange 1112 constituting the joint portion 111 of the body 11 is arranged on the outer surface 14 of the battery case 1, as illustrated in Figures 2 and 3. Furthermore, the flange 1112 is bent toward the outer surface of the battery case 1. The flange 1112 having such a configuration significantly improves the rigidity of the battery case 1 in the direction perpendicular to the longitudinal direction of the body 11. As a result, in the battery case 1 according to this embodiment, thermal strain in the direction perpendicular to the longitudinal direction of the body 11 is suppressed.

[0052] However, if the bent portion 1113 that tilts the flange 1112 is provided so as to overlap the first weld metal of the flange 1112, there is a risk of cracking in the first weld metal. In particular, if the metal plate is a high-strength steel plate, the hardness of the first weld metal is high. Therefore, the risk of cracking in the first weld metal due to the bending of the flange 1112 cannot be ignored.

[0053] In view of the above circumstances, in the battery case 1 according to this embodiment, the first weld metal is separated from the bent portion 1113. This suppresses cracking of the first weld metal and further enhances the reliability of the battery case 1.

[0054] The most basic embodiment of the battery case 1 according to this embodiment has been described above. A more preferred embodiment will be described below.

[0055] (Bending amount of flange 1112) In the bent portion 1113, it is preferable to bend the flange 1112 so that it follows the outer surface 14 of the battery case 1. That is, it is preferable that the mating surface S of the flange 1112 and the outer surface 14 of the battery case 1 are substantially parallel. It is also preferable that the angle θ that the mating surface S of the flange 1112 makes with respect to the vertical direction V is approximately 90 degrees. Furthermore, it is preferable that one of the pair of flanges 1112 constituting the joint portion 111 is in contact with the outer surface 14 of the battery case 1. This makes it possible to reduce the dimensions of the battery case 1. In electric vehicles, the space for mounting batteries is limited. By reducing the dimensions of the battery case, the volume occupied by the battery in the electric vehicle can be reduced, and the amount of energy stored per unit volume can be improved.

[0056] (Thickness and type of metal plate) The thickness of the metal plate is not particularly limited. A preferred thickness for the metal plate is 0.1 to 1.4 mm. The greater the thickness of the metal plate, the more the thermal distortion of the battery case 1 is suppressed. The smaller the thickness of the metal plate, the less weight the battery case 1 is reduced. The thickness of the metal plate can be applied according to the application of the battery case 1 and the battery having it. The thickness of the metal plate may be 0.2 mm or more, 0.5 mm or more, or 0.8 mm or more. The thickness of the metal plate may be 1.2 mm or less, 1.1 mm or less, or 1.0 mm or less. The thickness of the metal plate 11S can be measured using a micrometer or the like at a flat portion of the metal plate 11S.

[0057] The material of the metal plate can be aluminum plate, stainless steel plate, or steel plate. From the viewpoint of improving the corrosion resistance of the battery case 1, aluminum plate and stainless steel plate are preferred. On the other hand, from the viewpoint of reducing the thickness of the metal plate constituting the battery case 1 and making the battery case 1 lighter, it is preferable to use a steel plate, especially a high-strength steel plate, for the metal plate. When using a steel plate, it is preferable to use a nickel-plated steel plate. Nickel-plated steel plates have higher strength than aluminum plate and stainless steel plate, and corrosion resistance equal to or better than that of aluminum plate and stainless steel plate.

[0058] When the metal plate 11S is a nickel-plated steel plate, the battery case 1 according to this embodiment can also exhibit the effect of improving the corrosion resistance of the joint portion 111. This is because the joint portion 111 of the battery case 1 according to this embodiment has a configuration that excludes the end face 16 of the metal plate 11S and the first weld metal from the inner surface 15 of the battery case 1.

[0059] Conventional battery cases are obtained by assembling materials cut from nickel-plated steel sheets. At the edges of materials cut from nickel-plated steel sheets, the nickel plating layer is substantially absent, and the underlying steel sheet is exposed. Therefore, while the surface of the nickel-plated steel sheet has high corrosion resistance, the edges have low corrosion resistance.

[0060] In the joint 611 of a conventional battery case manufactured by seam welding, as illustrated in Figure 6, the end face 66 of the Ni-plated steel sheet is exposed to the inner surface 65 of the battery case. The inner surface 65 of the battery case comes into contact with the electrolyte, which is a corrosive liquid filled in the battery case. The electrolyte corrodes the end face 66 of the Ni-plated steel sheet. Fe leaches from the end face 66 into the electrolyte. The Fe leached into the electrolyte degrades the performance of the battery.

[0061] On the other hand, as shown in Figures 2 and 3, in the battery case 1 according to this embodiment, the flange 1112 of the Ni-plated steel sheet is joined to the outer surface 14 of the body 11, that is, outside the battery case 1. Therefore, the end face 16 at the tip of the flange 1112 is positioned outside the battery case 1. As a result, the end face 16 of the Ni-plated steel sheet is separated from the inner surface 15 of the battery case 1, and the corrosion resistance of the joint 111 of the battery case 1 is improved.

[0062] Unlike seam welding, laser welding can produce butt welded joints as illustrated in Figure 5. In butt welded joints, welding is performed with the end faces 66 of the base material butted together. Therefore, by laser welding both ends 6112 of the Ni-plated steel sheet as shown in Figure 5, the end faces 66 can be excluded from the inner surface 65 of the battery case 1.

[0063] However, when butt laser welding is performed, the laser weld metal 6111L is exposed on the inner surface 65. Similar to the edge of the Ni-plated steel sheet, there is no Ni-plated layer on the surface of the laser weld metal 6111L. This is because the Ni-plated layer melts and dissolves into the weld metal during laser welding. The Ni dissolved in the weld metal slightly improves the corrosion resistance of the weld metal. Therefore, the corrosion resistance of the weld metal provided on the Ni-plated steel sheet is higher than that of the base steel sheet exposed on the edge. However, the corrosion resistance of the weld metal is lower than that of the Ni-plated layer. Therefore, the weld metal may also corrode in the electrolyte, potentially degrading the performance of the battery.

[0064] On the other hand, as shown in Figures 4 and 5, and as shown in Figures 2 and 3, in the battery case 1 according to this embodiment, the flange 1112 of the Ni-plated steel sheet is joined by a first weld metal (i.e., laser weld metal 1111L or seam weld metal 1111S, etc.) located on the outside of the battery case 1. The first weld metal is excluded from the inner surface 15 of the battery case 1. This further improves the corrosion resistance of the joint 111 of the battery case 1, which is made of Ni-plated steel sheet.

[0065] Ni-plated steel sheets consist of a base steel sheet and a Ni-plating applied to the surface of the base steel sheet. The base steel sheet is preferably made of low-carbon aluminum-killed steel or IF steel (Interstitial 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: <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

[0066] Ni-based plating layers are plating layers that mainly consist of Ni and optionally contain alloying elements such as Co, Fe, and W. The amount of Ni deposited in Ni-based plating layers is, for example, 2.6 to 35.6 g / m². 2 It can be within the range of

[0067] The combined thickness of the base steel sheet and the Ni-based plating layer is preferably 0.20 mm or more. A combined thickness of 0.20 mm or more allows for the achievement of both the mechanical strength and corrosion resistance required for the battery case 1. More preferably, the combined thickness of the base steel sheet and the Ni-based plating layer is 0.25 mm or more, and even more preferably 0.30 mm or more.

[0068] On the other hand, the total thickness of the base steel sheet and the Ni-based plating layer is preferably 1.40 mm or less. By having a total thickness of 1.40 mm or less, it is possible to achieve both the mechanical strength and corrosion resistance required for the battery case 1 while suppressing an increase in the mass of the lithium-ion battery. The total thickness of the base steel sheet and the Ni-based plating layer is more preferably 1.00 mm or less, and even more preferably 0.80 mm or less.

[0069] Here, the total thickness of the base steel plate and the Ni-based plating layer may be different for the body 11 and the lid 12 of the battery case 1. For example, the total thickness of the base steel plate and the Ni-based plating layer in the Ni-based plated steel plate used as the material for the body 11 may be thinner than the total thickness of the base steel plate and the Ni-based plating layer in the Ni-based plated steel plate used as the material for the lid 12.

[0070] Furthermore, in the Ni-plated steel sheet described above, the thickness of the Ni-plated layer is preferably 0.3 μm or more per side. A thickness of 0.3 μm or more of the Ni-plated layer per side makes it possible to further improve the corrosion resistance required for the battery case 1. The thickness of the Ni-plated layer per side is more preferably 1.0 μm or more, and even more preferably 1.2 μm or more.

[0071] On the other hand, the thickness of the Ni-based plating layer per side is preferably 10.0 μm or less. By making the thickness of the Ni-based plating layer per side 10.0 μm or less, it is possible to further improve the corrosion resistance required for the battery case 1 while suppressing an increase in manufacturing costs. The thickness of the Ni-based plating layer per side is more preferably 3.0 μm or less, and even more preferably 2.0 μm or less.

[0072] Furthermore, the thickness of the Ni-based plating layer may differ between the inner surface 15 and the outer surface 14 of the battery case 1. More specifically, the thickness of the Ni-based plating layer located on the inner surface 15 of the battery case 1 may be thinner than the thickness of the Ni-based plating layer located on the outer surface 14 of the battery case 1. In this case, from the viewpoint of ensuring corrosion resistance, it is preferable that the thickness of the Ni-based plating layer located on the inner surface 15 of the battery case 1 be 0.5 μm or more, and the thickness of the Ni-based plating layer located on the outer surface 14 of the battery case 1 be 1.0 μm or more.

[0073] The thickness of the Ni-based plating layer and the total thickness of the base steel sheet and the Ni-based plating layer can be determined by observing the cross-section of the Ni-based plating steel sheet using a scanning electron microscope (SEM) (for example, a JSM-7000F manufactured by JEOL Corporation). Specifically, a sample for cross-sectional observation is cut from the Ni-based plating steel sheet located at any part of the body 11 of the battery case 1 other than the joint 111. The cutting direction for obtaining the cross-section is the thickness direction of the Ni-based plating steel sheet. After polishing the obtained sample for cross-sectional observation, SEM images are taken at any five locations on the cross-section. The thickness of the Ni-based plating layer and the thickness of the base steel sheet measured in each obtained SEM image are averaged over the number of measurement locations, and the resulting average values ​​are taken as the thickness of the Ni-based plating layer and the thickness of the base steel sheet, respectively.

[0074] Furthermore, in the Ni-plated steel sheet described above, various chemical conversion coating layers (not shown) may be present between the base steel sheet and the Ni-plated layer. The presence of such chemical conversion coating layers makes it possible to further improve the adhesion between the base steel sheet and the Ni-plated layer. In addition, the presence of such chemical conversion coating layers makes it possible to further improve the corrosion resistance of the Ni-plated steel sheet.

[0075] The chemical conversion coating layer is not particularly limited and can be formed using various chemical conversion treatments. Examples of such chemical conversion treatments include chromate-based chemical conversion treatments and non-chromate-based chemical conversion treatments. Examples of non-chromate-based chemical conversion treatments include chemical conversion treatments using inorganic compounds such as vanadium compounds, titanium compounds, zirconium compounds, and phosphate compounds, as well as silica-based chemical conversion treatments.

[0076] 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 from the underlying steel sheet is diffused to its surface, or it may be a partially diffused plating layer in which the Fe from 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.

[0077] (Type of first weld metal) As described above, preferred examples of the first weld metal are seam weld metal 1111S or laser weld metal 1111L. An example of seam weld metal 1111S is shown in Figure 2. An example of laser weld metal 1111L is shown in Figure 3. Here, the shape, etc., of the seam weld metal 1111S and laser weld metal 1111L are not particularly limited. Various forms suitable for the material and thickness of the metal plate can be applied to the first weld metal.

[0078] (Means for joining the lid 12 and the body 11) One example of a suitable joining method between the lid 12 and the body 11 is welding. Therefore, the joint 111 between the lid 12 and the body 11 may be a second weld metal 13. Suitable examples of the second weld metal 13 are arc weld metal and laser weld metal 1111L. Alternatively, flanges 1112 can be provided at the ends of the lid 12 and the ends of the body 11, and these flanges 1112 can be overlapped and joined with seam weld metal 1111S.

[0079] Another example of a suitable joining method between the lid 12 and the body 11 is crimping. Crimping is widely used as a means of joining the can body and the lid. Crimping can also be applied to the battery case 1 according to this embodiment. Therefore, the joining portion 111 between the lid 12 and the body 11 may be a crimped portion.

[0080] (Material of lid 12) The lid 12 can be manufactured from any material that can be joined to the body 11. The lid 12 is, for example, a metal plate, preferably a nickel-plated steel plate, a stainless steel plate, or an aluminum plate. The nickel-plated steel plate exemplified as the material for the body 11 can also be used for the lid 12.

[0081] (External dimensions of battery case 1) The length along the body 11 of the battery case 1, i.e., the distance X between the pair of lids 12, is preferably 1.5 times or more the length Y of the longer side of the lid 12. If the lid 12 is rectangular, the longer side Y of the lid 12 is the length of the longer side. If the lid 12 is square, the longer side Y of the lid 12 is the length of one side of the square. A battery case 1 having such a shape can be suitably used as a blade battery.

[0082] Furthermore, the distance X between the pair of lids 12 of the battery case 1 is preferably, for example, 100mm to 150mm, and more preferably 200mm to 400mm. The length of the long side Y of the lid 12 is preferably, for example, 50mm to 150mm, and more preferably 90mm to 120mm. The length of the short side Z of the lid 12 is preferably, for example, 10mm to 50mm, and more preferably 20mm to 40mm. The short side Z of the lid 12 is the length of the shorter side of the lid 12.

[0083] (edge ​​welding) The pair of flanges 1112 included in the joint 111 of the body 11 may be edge-welded, as shown in Figure 4. That is, the pair of flanges 1112 and the first weld metal may constitute an edge joint. In JIS Z 3001-1:2018, an edge joint is defined as "a joint in which the end faces of two parts are joined at an angle of 0°≦α≦30°". In the battery case 1 according to this embodiment, the first weld metal may be positioned at the tip of the flange 1112 to constitute an edge joint. This allows the first weld metal to be separated from the bent portion 1113, thereby more effectively preventing the occurrence of cracks in the first weld metal.

[0084] (2.Battery) A battery according to another aspect of the present disclosure has a battery case according to this embodiment. The battery case is the outer casing of the battery. The battery 2 further comprises an electrode body housed inside the battery case, positive and negative current collectors electrically connected to the electrode body, and an electrolyte. One lid of the battery case is provided with electrode terminals electrically connected to the current collectors. The lid is provided with an electrolyte injection port and an injection plug to seal the injection port. The lid is also provided with a cleavage valve port and a cleavage valve to seal the cleavage valve port. The cleavage valve port cleaves open when the pressure inside the battery case increases due to some abnormality, releasing the pressure inside the battery case.

[0085] In the battery according to this embodiment, thermal distortion in the direction perpendicular to the longitudinal direction of the body 11 of the battery case 1 is suppressed. Furthermore, in the battery according to this embodiment, cracking of the first weld metal is suppressed.

[0086] In the battery according to this embodiment, the battery case is preferably a neutral case. A neutral case is a battery case that is electrically insulated from the electrodes. The neutral case is electrically neutral.

[0087] Preferably, electrodes are arranged on the lid 12 of the battery case 1. By using a battery with electrodes arranged on the lid 12 as the battery for an electric vehicle, the thickness of the electric vehicle's floor can be reduced, and the passenger space in the electric vehicle can be expanded.

[0088] 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.

[0089] (3. Manufacturing method of battery case 1) A method for manufacturing a battery case 1 according to another aspect of the present disclosure is the method for manufacturing a battery case 1 as described above, comprising the steps of: providing flanges 1112 at both ends of a metal plate 11S; bending the metal plate 11S so that the flanges 1112 overlap each other on the outer surface 14 of the battery case 1 to form a cylindrical body; welding the overlapping pair of flanges 1112 to form a body 11; bending the flanges 1112 toward the outer surface 14 of the battery case 1 to form a bent portion 1113; and joining a lid 12 to the openings at both ends of the body 11, wherein the bent portion 1113 is positioned closer to the base end of the flange 1112 than the weld metal, and the bent portion 1113 is separated from the weld metal.

[0090] The method for manufacturing the battery case according to this embodiment will be described below. Naturally, the preferred embodiments of the battery case and battery described above can also be applied to the manufacturing method of the battery case 1.

[0091] (Step S1: Installing flange 1112) First, flanges 1112 are provided at both ends of the metal plate 11S. For example, as shown in Figure 8, a pair of flanges 1112 can be provided by bending both ends of the metal plate 11S. In this case, it is preferable to bend both ends of the metal plate 11S toward the surface used as the outer surface 14 of the fuselage 11. The pair of flanges 1112 extend from one end of the metal plate 11S forming one opening of the fuselage 11 to the other end of the metal plate 11S forming the other opening of the fuselage 11.

[0092] (Process S2: Bending the metal plate 11S) Next, the metal plate 11S is bent. Then, the pair of flanges 1112 are overlapped. This forms a cylindrical body. At this time, as shown in Figures 9A and 9B, for example, both of the pair of flanges 1112 are overlapped on the outer surface of the cylindrical body, i.e., the outer surface 14 of the battery case 1.

[0093] In the process of bending the metal plate 11S, the cross-sectional shape of the cylinder may be made to match the cross-sectional shape of the body 11 of the battery case 1 that is ultimately obtained. For example, if the body 11 of the battery case 1 is to be rectangular, it is preferable to make the above-mentioned cylindrical body into a rectangular cylinder, as illustrated in Figure 9A.

[0094] On the other hand, in the process of bending the metal plate 11S, the cross-sectional shape of the cylinder may be made different from the cross-sectional shape of the body 11 of the battery case 1 that is ultimately obtained. In this case, after welding the flange 1112 described later, and before joining the body 11 and the lid 12, the cylindrical body is deformed to match the shape of the body 11 of the battery case 1 that is ultimately obtained. The process of deforming the cylindrical body is sometimes referred to as the pipe expansion process. In this disclosure as well, for convenience, the process of deforming the cross-sectional shape of the cylindrical body will be referred to as the pipe expansion process. In the pipe expansion process, the cross-sectional area of ​​the cylindrical body may be increased or decreased. For example, if the cross-section of the cylindrical body is deformed from a circle to a rectangle, the cross-sectional area may decrease. Such an action is also referred to as the pipe expansion process.

[0095] If the manufacturing method of the battery case 1 includes a tube expansion step, it is preferable to make the cylindrical body cylindrical, as shown in Figure 9B, for example. In the tube expansion step, the cylindrical body can be deformed into a rectangular tube shape, as illustrated in Figure 9A, for example.

[0096] In Figures 9A and 9B, there is only one metal plate, but as illustrated in Figure 9C, the body 11 may be constructed using two or more metal plates. In the example shown in Figure 9C, each of the two metal plates is bent into a U-shape. Furthermore, both ends of each of the two metal plates are bent to form flanges 1112. The U-shaped metal plate with flanges 1112 at both ends, as shown in Figure 9C, is sometimes referred to as a hat-shaped member. By overlapping the flanges 1112 of the two metal plates, a cylindrical body can be formed.

[0097] Alternatively, one could first join multiple metal plates to form a single flat plate having a joint portion 111, and then bend this into a cylindrical shape to form a cylindrical body.

[0098] (Step S3: Welding a pair of flanges 1112) Next, the overlapping pair of flanges 1112 are welded together to form the fuselage 11. The welding is performed along the extending direction of the flanges 1112, from one opening to the other in the fuselage 11. The welding forms a first weld metal that joins the overlapping pair of flanges 1112 together.

[0099] One example of a welding method is seam welding. Figure 10A shows a schematic perspective view of a flange 1112 to be seam welded. Figure 10B shows a schematic cross-sectional view of a flange 1112 to be seam welded. In seam welding, a pair of disc electrodes 5 are used to apply pressure and current to the flange 1112, which is the base material for welding. While rotating the disc electrodes 5, the flange 1112 is resistance welded continuously along the flange 1112.

[0100] The disc electrode 5 can be, for example, a flat electrode or an R-type electrode. A flat electrode is an electrode in which the portion in contact with the base material is straight in the cross-section along the central axis of the electrode. An R-type electrode is an electrode in which the portion in contact with the base material is rounded in the cross-section along the central axis of the electrode. An R-type electrode is preferable because it concentrates the current.

[0101] The tip radius (R) of the R electrode is preferably 3 or greater. The tip radius (R) refers to the radius of curvature of the portion that contacts the base material in the cross-section along the central axis of the electrode. By setting the tip radius (R) to 3 or greater, dust generation when the nugget becomes larger can be suppressed.

[0102] To minimize the effects of electrode wear, seam welding may be replaced with wire seam welding. Wire seam welding is a type of seam welding in which a thin copper wire is belted around the circumference of a disc electrode, and this copper wire is used as the electrode.

[0103] Examples of preferred conditions for seam welding are as follows: • Diameter of disc electrode 5: Φ100~400mm • Width of disc electrode 5: 3-10 mm Welding speed: 2-20 m / min

[0104] Furthermore, it is preferable to cool the disc electrode. Cooling the disc electrode stabilizes the seam welding. For example, by circulating a coolant through the central axis to which the disc electrode is attached, seam welding can be performed while cooling the disc electrode.

[0105] As shown in Figure 10B, the distance between the disc electrode 5 used to weld the flange 1112 and the outer surface 14 around the base of the flange 1112 is preferably 0.5 mm or more, and more preferably 1 mm or more. By setting the distance between the disc electrode 5 and the outer surface 14 to 0.5 mm or more, contact between the disc electrode 5 and the outer surface 14 can be suppressed, thereby suppressing surface damage to the outer surface 14.

[0106] The upper limit of the distance between the disc electrode 5 and the outer surface 14 is a value corresponding to the width of the flange 1112. The width of the flange 1112 is preferably, for example, 2 to 15 mm. By setting the flange width to 2 mm or more, contact between the disc electrode 5 and the outer surface 14 can be suppressed, thereby preventing surface scratches on the outer surface 14. By setting the flange width to 15 mm or less, the weight of the battery case can be reduced.

[0107] In seam welding, nuggets may not be formed. If nuggets are not formed, the metal plates are pressure-welded. In the battery case manufacturing method according to this embodiment, seam welding without nugget formation is also permitted. In this disclosure, "seam-welded metal" is a concept that also includes the pressure-welded portion formed by seam welding.

[0108] Another example of a welding method is laser welding. In laser welding, laser light is used as the energy medium to weld the flange 1112. The laser welding conditions can be appropriately determined according to the thickness of the metal plate 11S, etc.

[0109] Examples of laser welding conditions are shown below. • Focusing diameter: 0.1~0.8mm • Output: Adjustable according to plate thickness and welding speed. Welding speed: 2-30 m / min • Defocusing: This is optional, but if you want to reduce sputtering, you can defocus by about 1% of the focal length. • Shielding gas: Not required, but nitrogen or argon gas may be used to suppress temper color. Furthermore, to suppress sputtering, the focusing shape may be changed using a DOE (diffraction grating) or the like.

[0110] (Step S4: bending the welded flange 1112) Next, the welded flange 1112 is bent toward the outer surface 14 of the fuselage 11, i.e., the outer surface 14 of the battery case 1. This forms a bent portion 1113 in the flange 1112 along from one opening to the other of the fuselage 11. At this time, the bend is made closer to the base end of the flange 1112 than the first weld metal. This allows the bent portion 1113 to be positioned closer to the base end of the flange 1112 than the first weld metal, and also separates the bent portion 1113 from the first weld metal.

[0111] (Step S5: Joining the lid 12 to the body 11) Finally, the lids 12 are joined to the openings at both ends of the body 11. This completes the battery case 1. One example of a method for attaching the lids 12 to the body 11 is crimping. Crimping is widely used in the manufacture of cans. Another example of a method for attaching the lids 12 to the body 11 is laser welding. In either case, the airtightness of the battery case 1 can be easily ensured.

[0112] The most basic aspects of the manufacturing method for the battery case 1 according to this embodiment have been described above. However, it should be noted that the manufacturing method for the battery case 1 according to this embodiment may have various additional steps. For example, the manufacturing method for the battery case 1 may further include a step of making through holes in the body 11 or the lid 12. Through holes include, for example, electrode insertion ports, opening valve ports, and liquid injection ports. If the body is made up of two or more metal plates, the manufacturing method for the battery case may include a step of joining the multiple metal plates that make up the body together.

[0113] Furthermore, in the manufacture of a battery comprising the battery case 1, it should be noted that the assembly of the battery case 1 and the installation of battery components into the battery case 1 can be carried out in parallel. For example, if the through-hole is a liquid injection port, the electrolyte can be injected into the battery case 1 through the through-hole and then the through-hole can be sealed. Also, various components such as electrodes can be installed inside the battery case 1 before joining the lid 12 to the body 11. When the battery case comprising the battery case 1 is a neutral can, the manufacturing method of the battery case 1 according to this embodiment can be increased by adding the steps of forming electrode insertion ports in the body 11 or lid 12 of the battery case 1 and assembling insulating material into the electrode insertion ports. The insulating material electrically insulates the electrodes from the battery case 1. Any steps necessary for manufacturing a battery can be appropriately added to the manufacturing method of the battery case 1 according to this embodiment. [Explanation of Symbols]

[0114] 1 Battery case 11 Torso 111 Joint 1111S Seam Weld Metal 1111i Indentation 1111L Laser Welded Metal 1112 Flange 1113 Bending section 11S metal plate 12 Lid 13 Second weld metal 14 Exterior 15. Inner self 2 batteries 3 Cooling plate 4. Filler 5. Disc electrodes 611 Joint 6111L Laser Welded Metal 6112 End 64 Exterior 65 Inner self S mating surface V Vertical direction θ: Angle made by the mating surfaces with respect to the vertical direction. X Distance between a pair of lids Y is the length of the longer side of the lid. Z is the length of the shorter side of the lid. α First plastic deformation part β Second plastic deformation part

Claims

1. A cylindrical body made of bent metal plates, A pair of covers that seal the openings at both ends of the body, A battery case equipped with, The body has at least a pair of overlapping flanges extending from one of the lids to the other lid and provided at the end of the metal plate, The flange is positioned on the outer surface of the battery case. The body has weld metal that extends from one of the lids to the other lid and joins the overlapping flanges to each other. The flange has a bent portion that bends the flange toward the outer surface of the battery case, extending from one cover to the other cover. The weld metal is positioned closer to the tip of the flange than the bent portion of the flange. The weld metal is separated from the bent portion. Battery case.

2. The battery case according to claim 1, wherein the bent portion bends the flange so that it conforms to the outer surface of the battery case.

3. The battery case according to claim 1 or 2, wherein the thickness of the metal plate is 0.1 to 1.4 mm.

4. The battery case according to claim 1 or 2, wherein the metal plate is a base steel plate and a Ni-plated steel plate having a Ni-plated layer provided on the surface of the base steel plate.

5. The battery case according to claim 4, wherein the thickness of the Ni-based plating layer is 0.1 to 10 μm.

6. The battery case according to claim 1 or 2, wherein the weld metal is seam weld metal or laser weld metal.

7. The battery case according to claim 1 or 2, wherein the joint between the lid and the body is a crimped portion or laser-welded metal.

8. The battery case according to claim 1 or 2, wherein the cover is made of Ni-plated steel sheet or stainless steel sheet.

9. The battery case according to claim 1 or 2, wherein the distance between the pair of lids is 1.5 times or more the length of the long side of the lids.

10. The battery case according to claim 1 or 2, wherein the weld metal is disposed at the tip of the flange.

11. A battery comprising the battery case described in claim 1 or 2.

12. The battery according to claim 11, wherein the battery case is electrically insulated from the electrodes.

13. A method for manufacturing a battery case according to claim 1 or 2, The process of attaching flanges to both ends of a metal plate, The process of bending the metal plate so that the flanges overlap each other on the outer surface of the battery case to form a cylindrical body, A step of welding the overlapping pair of flanges to form the fuselage, The process of bending the flange toward the outer surface of the battery case to form a bent portion, The process of joining the lid to the openings at both ends of the body, Equipped with, The bent portion is provided at a position closer to the base end of the flange than the weld metal. The bent portion is separated from the weld metal. A method for manufacturing battery cases.

14. The method for manufacturing a battery case according to claim 13, characterized in that the cylindrical body is rectangular in shape.

15. The aforementioned cylindrical body is cylindrical, The manufacturing method further comprises a step of deforming the cylindrical body into a rectangular tube shape before joining the lids to the openings at both ends of the body. A method for manufacturing a battery case according to claim 13.

16. The method for manufacturing a battery case according to claim 13, characterized in that the flange is seam-welded.

17. The method for manufacturing a battery case according to claim 13, characterized in that the flange is laser welded.

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