Sealing can body, battery cell case, and method for manufacturing sealing can body

Abstract

Provided are: a sealing can body (1) including a lid (10), a body (20), and a welding metal (30) that joins the lid (10) and the body (20), the sealing can body (1) being characterized in that the lid (10) is made of a stainless steel material and the body (20) is made of a plated steel material having a Ni-based plating layer on the surface of a base steel material, or the lid (10) is made of a plated steel material having a Ni-based plating layer on the surface of a base steel material and the body (20) is made of a stainless steel material, and in that [Cr] + 4 × [Ni] ≧ 5.0 is satisfied when [Cr] denotes the average amount of Cr in the welding metal (30) and [Ni] denotes the average amount of Ni in the welding metal (30); and a method for manufacturing said sealing can body.

Description

Sealed can body, battery cell case, and method of manufacturing sealed can body

[0001] This disclosure relates to a sealed can body, a battery cell case, and a method for manufacturing a sealed can body. This disclosure claims priority to Japanese Patent Application No. 2023-203653, filed on December 1, 2023, the contents of which are incorporated herein by reference.

[0002] Many of the batteries used in electric vehicles are lithium-ion batteries, and the battery cell cases that house the cells of these batteries come in a variety of shapes, including cylindrical, rectangular, and pouch-shaped. Of these, rectangular lithium-ion battery cell cases are often made of aluminum, as described in Patent Document 1. Patent Document 1 discloses an aluminum can for a secondary battery assembled by laser welding a lid and an exterior body made of an aluminum alloy plate, and a method for manufacturing the same.

[0003] Lithium-ion battery cell cases include stainless steel cases and cases made of plated steel. For example, Patent Document 2 discloses a rectangular sealed container for a prismatic battery in which a metal cover plate is fitted into a rectangular opening formed at one end of the metal case and the fitting is sequentially laser-welded. The case is made of nickel-plated steel.

[0004] Japanese Unexamined Patent Publication No. 2013-097900 Japanese Unexamined Patent Publication No. 08-315788

[0005] Prismatic battery cell cases such as those described above are often assembled by laser welding the top lid and body. However, the laser welded portion is covered with a small proportion of Ni plating, and compared to the base material that makes up the top lid and body, it is difficult to obtain the corrosion resistance improvement effect of plating. Therefore, under extremely severe conditions, it is possible that the inner surface of the welded portion may corrode. Furthermore, it is difficult to apply corrosion-resistant treatment to the inner surface of the welded portion after laser welding the top lid and body of the battery cell case.

[0006] The present disclosure has been made in view of the above, and aims to provide a sealed can body with highly corrosion-resistant laser welded parts, a method for manufacturing the same, and a battery cell case using the sealed can body.

[0007] (1) A sealed can body according to one aspect of the present disclosure is a sealed can body including a lid, a body, and a weld metal joining the lid and the body, wherein the lid is made of a stainless steel material, the body is made of a plated steel material having a Ni-based plating layer on a surface of a base steel material, and wherein, when an average Cr content of the weld metal is [Cr] and an average Ni content of the weld metal is [Ni], [Cr] + 4 × [Ni] ≥ 5.0 is satisfied. (2) In the sealed can body described in (1) above, the body may not have a weld. (3) A sealed can body according to one aspect of the present disclosure includes a lid, a body, and a weld metal joining the lid and the body, wherein the lid is made of a plated steel material having a Ni-based plating layer on a surface of a base steel material, and the body is made of a stainless steel material, and where the average Cr content of the weld metal is [Cr] and the average Ni content of the weld metal is [Ni], the following relationship is satisfied: [Cr] + 4 × [Ni] ≥ 5.0. (4) In the sealed can body described in (3) above, the body may have a welded portion. (5) In the sealed can body described in any one of (1) to (4) above, the C content of the base steel may be greater than 0 and not greater than 0.07 mass%. (6) In the sealed can body described in any one of (1) to (5) above, the stainless steel material may have a thickness of 0.1 to 1.4 mm, and the plated steel material may have a thickness of 0.1 to 1.4 mm. (7) In the sealed can body described in any one of (1) to (6) above, the Ni-based plating layer may have a thickness of 0.3 to 10 μm. (8) In the sealed can body described in any one of (1) to (7) above, an Fe—Ni alloy layer may be present between the Ni-based plating layer and the base steel material. (9) In the sealed can body described in any one of (1) to (8) above, the sealed can body may further include a bottom cover provided opposite the lid body, and at least one of the lid body and the bottom cover may be made of plated steel having a Ni-based plating layer on a surface of the base steel material. (10) A battery cell case according to one aspect of the present disclosure uses the sealed can body described in any one of (1) to (9) above.(11) A method for manufacturing a sealed can body according to one aspect of the present disclosure is a method for manufacturing a sealed can body including a lid, a body, and a weld metal joining the lid and the body, comprising the steps of: processing a stainless steel material to form the lid, processing a plated steel material having a Ni-based plating layer on a surface of a base steel material to form the body, and joining the lid and the body by welding, wherein, when the average Cr content of the weld metal is [Cr] and the average Ni content of the weld metal is [Ni], [Cr] + 4 × [Ni] ≥ 5.0 is satisfied. (12) In the method for manufacturing a sealed can body described in (11) above, the processing of the body may be deep drawing. (13) A method for manufacturing a sealed can body according to one aspect of the present disclosure is a method for manufacturing a sealed can body including a lid, a body, and a weld metal joining the lid and the body, the method including: a step of forming the lid by processing a stainless steel material; a step of forming the body by processing a non-plated steel material; a step of providing a Ni-based plating layer on a surface of the body; and a step of joining the lid and the body by welding, wherein when an average Cr content of the weld metal is [Cr] and an average Ni content of the weld metal is [Ni], the method satisfies [Cr] + 4 × [Ni] ≥ 5.0. (14) A method for manufacturing a sealed can body according to one aspect of the present disclosure is a method for manufacturing a sealed can body including a lid, a body, and a weld metal joining the lid and the body, comprising the steps of: processing a stainless steel material to form the body, processing a plated steel material having a Ni-based plating layer on a surface of a base steel material to form the lid, and joining the lid and the body by welding, wherein, when the average Cr content of the weld metal is [Cr] and the average Ni content of the weld metal is [Ni], [Cr] + 4 × [Ni] ≥ 5.0 is satisfied. (15) In the method for manufacturing a sealed can body described in (14) above, the processing of the body may be welding.

[0008] The laser welded portions of the sealed can body according to the present disclosure and the battery cell case using the sealed can body according to the present disclosure have high corrosion resistance. Furthermore, the method for manufacturing a sealed can body according to the present disclosure can provide a sealed can body with highly corrosion-resistant laser welded portions.

[0009] 1 is a schematic perspective view illustrating a sealed can body according to an embodiment of the present disclosure; FIG. 2 is a schematic perspective view illustrating a modified example of a sealed can body according to an embodiment of the present disclosure; FIG. 3 is a view illustrating an example of a lid and a body in the vicinity of a welded portion of a sealed can body according to an embodiment of the present disclosure, the view being a schematic cross-sectional view of the sealed can body taken on a plane perpendicular to the weld line; FIG. 4 is a view illustrating another example of a lid and a body in the vicinity of a welded portion of a sealed can body according to an embodiment of the present disclosure, the view being a schematic cross-sectional view of the sealed can body taken on a plane perpendicular to the weld line; FIG. 5 is a view illustrating another example of a lid and a body in the vicinity of a welded portion of a sealed can body according to an embodiment of the present disclosure, the view being a schematic cross-sectional view of the sealed can body taken on a plane perpendicular to the weld line; FIG. 6 is a schematic perspective view illustrating a modified example of a sealed can body according to an embodiment of the present disclosure; FIG. 7 is a view illustrating another example of a lid and a body in the vicinity of a welded portion of a sealed can body according to an embodiment of the present disclosure, the view being a schematic cross-sectional view of the sealed can body taken on a plane perpendicular to the weld line. FIG. 10 is a diagram for explaining another example of a lid body and a body body in the vicinity of a welded portion of a sealed can body according to an embodiment of the present disclosure, and is a schematic cross-sectional view of the sealed can body taken along a plane perpendicular to the weld line.

[0010] Hereinafter, embodiments of the present disclosure will be described using examples, but it is clear that the present disclosure is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be used as examples, but other numerical values ​​and materials may be applied as long as the effects of the invention according to the present disclosure are obtained. Furthermore, the components of the following embodiments can be combined with each other. Furthermore, in this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. In this specification, the term "process" includes not only an independent process, but also a process that cannot be clearly distinguished from other processes as long as the intended purpose of the process is achieved.

[0011] In the following embodiments, the term "steel material" refers to a steel plate, a part machined from a steel plate into a shape other than a flat plate, or a steel plate formed by joining different types of steel plates together. The term "stainless steel material" refers to a stainless steel plate or a part machined from a stainless steel plate into a shape other than a flat plate.

[0012] [Sealed Can Body] Fig. 1 shows a sealed can body 1 according to this embodiment. The sealed can body 1 of this embodiment includes a lid body 10, a body body 20, and a weld metal 30 that joins the lid body 10 and the body body 20. A sealed can body has a sealed structure that prevents contents such as a liquid from leaking to the outside of the sealed can body. The sealed can body 1 of this embodiment has a structure in which the lid body 10 and the body body 20 are joined by the weld metal 30, and therefore prevents contents inside the sealed can body 1 from leaking to the outside. To achieve this structure, a weld is formed around the entire periphery of the joint between the lid body 10 and the body body 20. The weld is a portion that includes the weld metal 30.

[0013] [Lid] The lid 10 is joined to the body 20 to form the sealed can body 1. As will be described later, the material forming the lid 10 is a stainless steel material or a plated steel material having a Ni-based plating layer on the surface of a base steel material. In the example of Fig. 1, the surface of the lid 10 is parallel to the X- and Y-coordinate axes.

[0014] The lid 10 may be made of, for example, a single steel plate, or may be made by overlapping a plurality of steel plates, stainless steel plates, or the like. Alternatively, it may be made by joining these metal plates by welding or the like. The lid 10 may be provided with a liquid injection port for injecting an electrolyte after sealing the sealed can 1, a hole for passing an electrode, a notch, a protrusion, a recess, or the like.

[0015] 1, the lid 10 is connected to an opening 21 of the body 20, which will be described later, and is disposed so as to face the bottom surface 20e. As will be described later, the lid 10 may be provided with a raised portion 11 and an edge portion 12, or alternatively with the edge portion 12, on its outer periphery.

[0016] [Fuselage] As illustrated in Fig. 1, the fuselage 20 is composed of opposing side surfaces 20a and 20b, opposing side surfaces 20c and 20d, and a bottom surface 20e. Side surfaces 20a, 20b, 20c, and 20d are each connected at one end to a corresponding end of the bottom surface 20e and are configured to rise from the bottom surface 20e. Each of the side surfaces 20a, 20b, 20c, and 20d intersects with the bottom surface 20e. In the example of Fig. 1, the bottom surface 20e is parallel to the X and Y coordinate axes, and the side surfaces 20a, 20b, 20c, and 20d are parallel to the Z coordinate axis.

[0017] One of the ends of side surface 20a extending in a direction intersecting with bottom surface 20e is connected to the end of side surface 20c, and the other is connected to the end of side surface 20d. One of the ends of side surface 20b extending in a direction intersecting with bottom surface 20e is connected to the end of side surface 20c, and the other is connected to the end of side surface 20d. In the example of FIG. 1, side surface 20a and side surface 20b are parallel to the Y coordinate axis and the Z coordinate axis, and side surface 20c and side surface 20d are parallel to the X coordinate axis and the Z coordinate axis. Also, in the example of FIG. 1, each end connecting side surface 20a, side surface 20b, side surface 20c, and side surface 20d to each other is parallel to the Z coordinate axis.

[0018] The body 20 has an opening 21, and the lid 10 is joined to this opening 21. The opening 21 is defined by the end of each of the side surfaces 20a, 20b, 20c, and 20d that faces the end connected to the bottom surface 20e. Because the sealed can 1 is sealed as described above, it is preferable that the outer shape of the lid 10 and the inner or outer shape of the opening 21 of the body 20 match each other. The inner shape of the opening 21 of the body 20 refers to a shape that corresponds to the inner shape of the body 20. Furthermore, the outer shape of the opening 21 of the body 20 refers to a shape that corresponds to the outer shape of the body 20.

[0019] [Bottom lid] Fig. 2 is a schematic perspective view illustrating a modified example of the sealed can body 1 according to the present embodiment. As illustrated in Fig. 2, the body 20 may not be provided with the bottom surface 20e, and a member similar to the lid body 10 may be used as the bottom lid 40.

[0020] The material constituting the bottom cover 40 may be the same as that of the cover body 10, or may be different. The bottom cover 40 and the body 20 are preferably joined with a weld metal having substantially the same composition as the weld metal 30 joining the cover body 10 and the body 20. The shape of the bottom cover 40 may also be the same as that of the cover body 10. In the example of FIG. 2 , the bottom cover 40 is connected to an opening 22 provided on the opposite side of the opening 21 of the body 20, and the cover body 10 and the bottom cover 40 are arranged so that their surfaces face each other. The bottom cover 40 may have a raised portion and an edge, or an edge, on the outer periphery, and these portions may be joined to the body 20.

[0021] The X, Y, and Z coordinate axes in FIGS. 1 and 2 are perpendicular to each other.

[0022] [Stainless Steel Material] The chemical composition of the stainless steel material is as follows: Cr (chromium): more than 10.00 and 30.00 mass% or less, C (carbon): 0 to 0.100 mass%, Si (silicon): 0 to 1.20 mass%, Mn (manganese): 0 to 5.00 mass%, P (phosphorus): 0 to 0.050 mass%, S (sulfur): 0 to 0.0500 mass%, Ni (nickel): 0 to 25.00 mass%, Mo (molybdenum): 0 to 4.00 mass%, Cu (copper): 0 to 3.00 mass%, Ti (titanium): 0 to 0.800 mass%, Al (aluminum): 0 to 0.30 mass%, Co (cobalt): 0 to 1.00 mass%, Nb (niobium): 0 to 0.800 mass%, N (nitrogen): 0 to 0.3000 mass%, Preferably, the stainless steel contains 0 to 0.500 mass% Sn (tin), with the remainder containing Fe (iron) and impurities. Impurities refer to components contained in raw materials or components mixed in during the manufacturing process, but not intentionally added. For example, trace amounts of components other than Fe, such as W, Mg, and B, may also be mixed in as impurities. Stainless steel materials with such a chemical composition are preferred in that they have excellent corrosion resistance (particularly corrosion resistance to the electrolyte contained therein (electrolyte resistance)).

[0023] The chemical composition of the stainless steel material is measured using ICP (Inductively Coupled Plasma) optical emission spectrometry, except that C (carbon), S (sulfur), and N (nitrogen) are measured by well-known gas analysis.

[0024] It is more preferable that the thickness of the stainless steel material is 0.1 to 1.4 mm. This has the advantage of producing a battery cell case that is lightweight and has excellent mechanical strength. The thickness of the stainless steel material is measured at five points using a micrometer, and the arithmetic average of these measurements is taken as the thickness of the stainless steel material.

[0025] [Plated Steel Material] The plated steel material is a steel material having a Ni-based plating layer on its surface. The chemical composition of the base steel material is: C (carbon): more than 0 and 0.090 mass% or less; Si (silicon): more than 0 and 0.800 mass% or less; Mn (manganese): more than 0 and 1.00 mass% or less; P (phosphorus): more than 0 and 0.05 mass% or less; S (sulfur): more than 0 and 0.050 mass% or less; Mo (molybdenum): 0 to 0.300 mass%; Cu (copper): 0 to 0.30 mass%; Ti (titanium): 0 to 0.100 mass%; Al (aluminum): 0 to 0.10 mass%; Co (cobalt): 0 to 0.1 mass%; Nb (niobium): 0 to 0.100 mass%; N (nitrogen): 0 to 0.0300 mass%; Sn (tin): 0 to 0.03 mass%; Cr (chromium): 0 to 0.20 mass%; Ni (nickel): 0 to 0.2 mass%. It is preferable that the steel sheet contains 0 to 0.0030 mass% of B (boron), with the remainder being Fe (iron) and impurities. Impurities refer to components contained in raw materials or components mixed in during the manufacturing process, but not intentionally added. For example, trace amounts of components other than Fe, such as W, Mg, and V, may also be mixed in as impurities. A base steel sheet having such a chemical composition is preferable in that it has excellent formability.

[0026] The chemical composition of the base steel material of the plated steel material is measured using ICP (Inductively Coupled Plasma) optical emission spectroscopy in accordance with JIS G 1258-1:2014, except that C (carbon), S (sulfur), and N (nitrogen) are measured by well-known gas analysis.

[0027] The carbon content of the base steel material (substrate) is more preferably greater than 0 and not greater than 0.07% by mass. This provides the advantage of even better formability. Dissolution of metal ions into the electrolyte may adversely affect battery performance. Therefore, materials used for battery cell cases are required to have corrosion resistance (electrolyte resistance). In terms of corrosion resistance, Ni-based plated steel and stainless steel are suitable. On the other hand, platings such as zinc-based plated steel, which exhibit corrosion resistance, particularly in the natural environment, through a sacrificial corrosion protection mechanism, can dissolve large amounts of ions into the electrolyte, making them unsuitable for use as materials for battery cell cases. For example, zinc-based plated steel, which does not require electrolyte resistance and is less expensive than Ni-based plated steel, is used as a material for general structures such as building materials.

[0028] A Ni-based plating layer is provided on the surface of a base steel material that constitutes a plated steel material. The Ni-based plating layer is a plating layer containing Ni as a main component. Specifically, the Ni-based plating layer is defined as a layer having a Ni concentration of 80 mass% or more when measured using GDS (Glow Discharge Optical Emission Spectrometry).

[0029] The thickness of the Ni-based plating layer is more preferably 0.3 to 10.0 μm. Increasing the thickness of the Ni-based plating layer improves the electrolyte resistance, but increases the cost. Setting the thickness of the Ni-based plating layer to 0.3 to 10.0 μm has the advantage of achieving an excellent balance between electrolyte resistance and cost. The thickness of the Ni-based plating layer can be measured using a GDS device. Using the GDS device, the thickness of the plating layer is measured at any five points, and the arithmetic mean value of these measurements is taken as the thickness of the Ni-based plating layer.

[0030] An Fe—Ni alloy layer may be present between the Ni-based plating layer and the base steel material. The Fe—Ni alloy layer is a layer having a Ni concentration of 10 to less than 80 mass %. The presence of the Fe—Ni alloy layer improves corrosion resistance and formability. The Fe—Ni alloy layer can be measured using a GDS device.

[0031] From the viewpoint of improving workability, the thickness of the Fe—Ni alloy layer is preferably 0.2 μm or more, and more preferably 0.5 μm or more. The thickness of the Fe—Ni alloy layer can be measured using a GDS device. The thickness is measured at five points using the GDS device, and the arithmetic average value of these measurements is taken as the thickness of the Fe—Ni alloy layer.

[0032] A Ni-W-based plating layer may be further provided on the Ni-based plating layer. Having a Ni-W-based plating layer on the surface improves corrosion resistance and formability. The Ni-W-based plating layer is defined as the range in which the W concentration is 10 mass% or more when measured using GDS. The thickness of the Ni-W-based plating layer can be measured using a GDS device. The thickness is measured at five points using the GDS device, and the arithmetic average of these measurements is defined as the thickness of the Ni-W-based plating layer.

[0033] It is more preferable that the thickness of the plated steel material be 0.1 to 1.4 mm. This has the advantage of producing a battery cell case that is lightweight and has excellent mechanical strength. The thickness of the plated steel material is measured at five points using a micrometer, and the arithmetic average of these measurements is taken as the thickness of the plated steel material.

[0034] In the sealed can body 1 of this embodiment, the lid body 10 is made of stainless steel, and the body body 20 is made of plated steel having a Ni-based plating layer on the surface of the base steel. With this configuration, the amount of alloy elements in the weld metal can be increased, thereby improving the corrosion resistance of the weld metal. By using stainless steel for one of the lid body 10 and the body body 20 and plated steel for the other, it is not necessary to use expensive stainless steel as the entire constituent material of the sealed can body 1. Furthermore, because plated steel has good formability, using plated steel for the body 20 can reduce manufacturing costs.

[0035] As illustrated in Figure 2, if the body 20 does not have a bottom surface 20e and a material similar to the lid body 10 is used as the bottom cover 40, the body 20 (side surface 20a, side surface 20b, side surface 20c, and side surface 20d) may be made of plated steel, and the lid body 10 and the bottom cover 40 may be made of stainless steel.

[0036] When the body 20 is made of plated steel, it is preferable that there are no welds in the body 20. For example, the body 20 can be formed by deep drawing or the like to form a body 20 without any welds. Because there are no welds, the body 20 has excellent corrosion resistance without the need for special treatment.

[0037] Alternatively, in the sealed can body 1 of this embodiment, the lid body 10 is made of a plated steel material having a Ni-based plating layer on the surface of the base steel material, and the body body 20 is made of a stainless steel material. With such a configuration, the amount of alloy elements in the weld metal can be increased, and the corrosion resistance of the weld metal can be improved. By using stainless steel for one of the lid body 10 and the body body 20 and plated steel for the other, it is not necessary to use expensive stainless steel for all of the constituent materials of the sealed can body 1.

[0038] 2, when the body 20 does not have a bottom surface 20e and a member similar to the lid 10 is used as the bottom cover 40, the body 20 (side surfaces 20a, 20b, 20c, and 20d) may be made of stainless steel, and the lid 10 and the bottom cover 40 may be made of plated steel. Alternatively, the body 20 may be made of stainless steel, and only one of the lid 10 and the bottom cover 40 may be made of plated steel, and the other may be made of stainless steel.

[0039] When the body 20 is made of stainless steel, it is preferable that there be welds in the body 20. For example, the body 20 having welds can be formed by forming the body 20 by welding or the like. Compared to plated steel, stainless steel has low formability, so welding has the advantage of being easy to process into a predetermined shape.

[0040] [Weld Metal] In the sealed can body 1 of this embodiment, when the average Cr content of the weld metal is [Cr] and the average Ni content is [Ni], [Cr] + 4 × [Ni] (corrosion resistance index) is 5.0 or more. The average Cr content of the weld metal 30 is measured using ICP (Inductively Coupled Plasma) optical emission spectroscopy. The Cr content of five points in the weld metal is measured, and the arithmetic average of these values ​​is defined as the average Cr content. The average Ni content in the weld metal is also calculated using the same method as the average Cr content.

[0041] The weld metal 30 is a portion of the welded joint where steel materials or the like are melted and solidified by irradiation with a laser beam during laser welding. It is a metal that melts and solidifies during welding. When a filler is used during laser welding, the source of the material for the weld metal 30 is the multiple steel materials to be joined and the filler. When the steel materials are plated, the components of the plating also melt and become materials that make up the weld metal. In addition to elements from these sources, the weld metal may also incorporate oxygen and nitrogen from the air, as well as unavoidable impurities. As described above, by using stainless steel for one of the lid body 10 and the body 20 and plated steel for the other, the amount of alloying elements in the weld metal can be increased, improving the corrosion resistance of the weld metal.

[0042] In the sealed can body 1 illustrated in FIG. 1 , the weld metal 30 extends along the X and Y coordinate axes and is formed around the outer periphery of the lid body 10 and the entire periphery of the opening 21 of the body body 20 .

[0043] For example, the thickness of the plated steel material that makes up the lid or body may be reduced to adjust the components that dissolve into the weld metal. The thickness adjustment process is preferably performed by pressing so as not to affect the plated layer.

[0044] (Joint Shape 1) An example of a joint shape at the joint between the lid body 10 and the body 20 will be described below. FIG. 3 is a diagram for explaining an example of the lid body 10 and the body 20 in the vicinity of the welded portion of the sealed can body according to this embodiment. FIG. 3 is a schematic cross-sectional view of the sealed can body 1 in a plane perpendicular to the extending direction of the weld line of the weld metal 30. In the example of FIG. 3 , the lid body 10 has a rising portion 11 and an edge portion 12. The rising portion 11 and the edge portion 12 are provided along the outer periphery of the lid body 10. By providing such a rising portion 11 and the edge portion 12, the edge portion 12 of the lid body 10 can engage with the opening 21 of the body 20 and support the lid body 10.

[0045] 3 , the weld metal 30 is provided over the end of the body 20 on the opening 21 side and at least the edge 12. The weld metal 30 may extend up to the rising portion 11.

[0046] (Joint Shape 2) Fig. 4 is a diagram for explaining another example of the lid 10 and the body 20 in the vicinity of the welded portion of the sealed can body according to the present embodiment. Fig. 4 is a schematic cross-sectional view of the sealed can body 1 in a plane perpendicular to the extending direction of the weld line of the weld metal 30. In the example of Fig. 4, the lid 10 has a raised portion 11. The raised portion 11 is provided along the outer periphery of the lid 10. Providing such a raised portion has the advantage that the cut end surface of the plated steel material, which is less protected by the plating, is not exposed to the inner surface.

[0047] As shown in FIG. 4 , the weld metal 30 is provided on the end of the body 20 on the opening 21 side, the vicinity thereof, and across the rising portion 11 .

[0048] (Joint Shape 3) Fig. 5 is a diagram illustrating another example of the lid 10 and the body 20 near the welded portion of the sealed can body according to this embodiment. Fig. 5 is a schematic cross-sectional view of the sealed can body 1 taken along a plane perpendicular to the direction in which the weld line of the weld metal 30 extends. In the example of Fig. 5, the lid 10 is made of stainless steel, and the body 20 is made of plated steel having a Ni-based plating layer on the surface of the base steel. Although the cut end surface of the lid 10 is exposed to the inner surface, the lid 10 has high corrosion resistance because it is made of stainless steel. Since there is no need to provide the raised portion 11 or edge portion 12 on the lid 10 or the body 20, there is an advantage in that manufacturing costs can be reduced.

[0049] As shown in FIG. 5 , the weld metal 30 is provided on the end of the body 20 on the opening 21 side and its vicinity, and across the cut end surface of the lid 10 .

[0050] (Joint Shape 4) Fig. 6 is a diagram illustrating another example of the lid 10 and the body 20 near the weld of the sealed can body according to this embodiment. Fig. 6 is a schematic cross-sectional view of the sealed can body 1 taken along a plane perpendicular to the direction in which the weld line of the weld metal 30 extends. In the example of Fig. 6, the lid 10 is made of a plated steel material having a Ni-based plating layer on the surface of the base steel material, and the body 20 is made of a stainless steel material. Although the cut end surface of the body 20 is exposed to the inner surface, the body 20 has high corrosion resistance because it is made of a stainless steel material. Since there is no need to provide the raised portion 11 or edge portion 12 on the lid 10 or the body 20, there is an advantage in that manufacturing costs can be reduced.

[0051] As shown in FIG. 6 , the weld metal 30 is provided on the end of the body 20 on the opening 21 side and its vicinity, and across the cut end surface of the lid 10 .

[0052] For example, when the sealed can body 1 of the present embodiment is used as a battery cell case that houses cells of a lithium-ion battery for an electric vehicle, by making the joint shape of the body 20 a shape that does not protrude toward the outer surface of the body 20, as illustrated in FIGS. 3 to 6, there are advantages in that the cell cases can be arranged without gaps and do not interfere with other components when they are arranged.

[0053] In the sealed can 1 according to this embodiment, the length L of the body 20 in the direction perpendicular to the lid 10 may be longer than the length W of the lid 10 in the longitudinal direction. For example, without any particular limitation, the length L of the body 20 in the direction perpendicular to the lid 10 may be 1.5 times or more the length W of the lid 10 in the longitudinal direction. This has the advantage that, even in a space with limited vertical space, the lid 10 equipped with terminals can be arranged horizontally to achieve a battery space factor. For example, by using a battery with terminals arranged on the lid 10 arranged horizontally as the battery of an electric vehicle, the thickness of the floor of the electric vehicle can be reduced, thereby expanding the living space of the electric vehicle.

[0054] 7 illustrates a sealed can 1 in which the length L of the body 20 in a direction perpendicular to the lid 10 is longer than the length W of the lid 10 in the longitudinal direction. The direction perpendicular to the lid 10 refers to the direction perpendicular to the plate surface of the lid 10. In the example of FIG. 7, the length L of the body 20 in the direction perpendicular to the lid 10 is the length in a direction parallel to the Z coordinate axis of the body 20. The length W of the lid 10 in the longitudinal direction refers to the maximum length of the lid 10 in a direction parallel to the plate surface of the lid 10. In the example of FIG. 7, the length W of the lid 10 in the longitudinal direction is the length in a direction parallel to the X coordinate axis of the lid 10.

[0055] 7, a bottom cover 40 is provided opposite the lid 10, similar to the example of FIG. 2. Furthermore, in the sealed can body 1 shown in FIG. 7, a welded portion (weld metal 31) is present in the body 20. Such a sealed can body 1 is not particularly limited, and can be manufactured, for example, by a manufacturing method (manufacturing method 3B of a sealed can body) which will be described later.

[0056] A method for manufacturing a sealed can body according to this embodiment will be described below. This manufacturing method makes it possible to suitably manufacture a sealed can body having highly corrosion-resistant laser welded parts. However, it is obvious that a sealed can body obtained by a method other than the manufacturing method described below can also be considered as the above-described sealed can body as long as it satisfies the requirements of the present application.

[0057] [Method 1A for manufacturing a sealed can body] A method for manufacturing a sealed can body according to this embodiment includes the steps of: forming a lid by processing a stainless steel material; processing a plated steel material having a Ni-based plating layer on the surface of a base steel material to form a body; and joining the lid and the body by welding.

[0058] (Lid forming process) The lid 10 is formed by processing a stainless steel material into a predetermined shape. As described in the above embodiment, the lid 10 may have a raised portion 11 and a rim 12, or the rim 12 may be provided on the outer periphery thereof.

[0059] (Process for forming the body) The body 20 is formed by processing a plated steel material having a Ni-based plating layer on the surface of the base steel material. Examples of processing include deep drawing and welding. Deep drawing is, for example, press-forming a single plated steel sheet to form the body 20 having the side surface 20a, side surface 20b, side surface 20c, side surface 20d, and bottom surface 20e described in the above embodiment. When steel material is processed by deep drawing, the body 20 is made of a single steel material (e.g., a steel sheet), and therefore no welds are present on the side surface 20a, side surface 20b, side surface 20c, side surface 20d, and bottom surface 20e.

[0060] In welding, for example, plated steel sheets that will become side surface 20a, side surface 20b, side surface 20c, side surface 20d, and bottom surface 20e are prepared and then welded together to form body 20. Alternatively, side surface 20a, side surface 20b, side surface 20c, side surface 20d, and bottom surface 20e may be formed by bending a single steel sheet, and then these ends may be joined to form body 20. When steel is processed by welding, at least one weld is present in body 20. In this case, the weld metal of the welded portion of body 20 is welded using a filler wire or the like such that [Cr] + 4 × [Ni] (corrosion resistance index) is 5.0 or greater, where [Cr] is the average Cr content of the weld metal and [Ni] is the average Ni content of the weld metal.

[0061] When the plated steel material is processed into the body 20, it is preferable to use deep drawing for processing the body 20. The body 20 formed by deep drawing does not have any welds, and therefore has excellent corrosion resistance without the need for special treatment (for example, plating treatment, film formation treatment, or painting after welding).

[0062] (Joining Step) In the joining step, the lid body 10 and the body 20 are joined by laser welding. In the laser welding, as long as appropriate welding can be performed, for example, the laser beam may be irradiated from any of the directions indicated by arrows A to F in the figure.

[0063] 8 shows an example in which the weld metal 30 is provided over the end of the body 20 on the opening 21 side and at least the edge 12 in the joint shape shown in FIG. 3. In this case, the laser light may be irradiated from the direction of arrow A or B in FIG. 8, for example.

[0064] 9 shows the joint shape shown in FIG. 4 , in which weld metal 30 is provided in the vicinity of the end of body 20 on the opening 21 side and in the vicinity of the end of rising portion 11. In this case, the laser light may be irradiated from the direction of arrow D or E in FIG. 9 , for example.

[0065] [Method 1B for manufacturing a sealed can body] When manufacturing a sealed can body 1 configured with a lid body 10, a body body 20, and a bottom lid 40 as illustrated in FIG. 2, the process for forming the body body 20 is different from the method 1A for manufacturing a sealed can body described above.

[0066] For example, body 20 having opening 21 may be formed from a plated steel material by deep drawing as described above, and the bottom surface may be cut away to form opening 22. Alternatively, side surfaces 20a, 20b, 20c, and 20d may be formed by bending a single steel plate in the same direction. In this case, the ends of the bent steel plate may be joined by caulking or welding. Alternatively, body 20 having side surfaces 20a, 20b, 20c, and 20d may be formed by joining multiple steel plates.

[0067] The bottom cover 40 may be manufactured by the same process as the cover 10. In the joining process, the joining of the bottom cover 40 and the body 20 may be performed under the same conditions as the joining of the cover 10 and the body 20.

[0068] [Method 2A for manufacturing a sealed can body] A method for manufacturing a sealed can body according to this embodiment includes the steps of: forming a lid by processing a stainless steel material; forming a body by processing a non-plated steel material; providing a Ni-based plating layer on the surface of the body; and joining the lid and the body by welding.

[0069] (Lid forming process) The lid 10 is formed by processing a stainless steel material into a predetermined shape. As described in the above embodiment, the lid 10 may have a raised portion 11 and a rim 12, or the rim 12 may be provided on the outer periphery thereof.

[0070] (Process for forming the body) The body 20 is formed by processing an unplated steel material. Examples of processing include deep drawing and welding. Deep drawing is performed by press-forming, for example, a single unplated steel plate, to form the body 20 having the side surface 20a, the side surface 20b, the side surface 20c, the side surface 20d, and the bottom surface 20e described in the above embodiment. When steel material is processed by deep drawing, the body 20 is made of a single steel material (for example, a steel plate), and therefore no welds are present on the side surface 20a, the side surface 20b, the side surface 20c, the side surface 20d, and the bottom surface 20e.

[0071] In the welding process, for example, unplated steel materials that will become side surface 20a, side surface 20b, side surface 20c, side surface 20d, and bottom surface 20e are prepared and then welded together to form body 20. Alternatively, side surface 20a, side surface 20b, side surface 20c, side surface 20d, and bottom surface 20e may be formed by bending a single steel plate, and then these ends may be joined together to form body 20. Note that, since a Ni-based plating layer is provided so as to cover the welded portion after welding, the weld metal included in the weld between unplated steel materials does not need to satisfy the composition requirements of weld metal 30 described above.

[0072] (Step of Providing a Ni-Based Plating Layer) After forming the body 20, a Ni-based plating layer is provided on the surface of the body 20. There are no limitations on the method for providing a Ni-based plating layer on the surface of the body 20, but for example, a Ni-based plating layer can be provided on the surface of the body 20 by electroplating the body 20 using a Ni plating bath (a Watts bath (pH = 3.0) containing 250 g / L of nickel sulfate, 50 g / L of nickel chloride, and 30 g / L of boric acid). It should be noted that the surface of the body 20 refers to both the inner and outer surfaces of the body 20.

[0073] (Joining Step) In the joining step, the lid body 10 and the body 20 are joined by laser welding. In the laser welding, as long as appropriate welding can be performed, for example, the laser beam may be irradiated from any of the directions indicated by arrows A to F in the figure.

[0074] [Method 2B for manufacturing a sealed can body] When manufacturing a sealed can body 1 including a lid body 10, a body body 20, and a bottom lid 40 as shown in FIG. 2, the process for forming the body body 20 is different from the method 2A for manufacturing a sealed can body described above.

[0075] For example, the body 20 having the opening 21 may be formed from an unplated steel material by deep drawing as described above, and the bottom surface may be cut away to form the opening 22. Alternatively, the side surfaces 20a, 20b, 20c, and 20d may be formed by bending a single steel plate in the same direction. In this case, the ends of the bent steel plate may be joined by caulking or welding. Alternatively, the body 20 having the side surfaces 20a, 20b, 20c, and 20d may be formed by joining a plurality of steel plates.

[0076] The bottom cover 40 may be manufactured by the same process as the cover 10. In the joining process, the joining of the bottom cover 40 and the body 20 may be performed under the same conditions as the joining of the cover 10 and the body 20.

[0077] [Method 3A for manufacturing a sealed can body] A method for manufacturing a sealed can body according to this embodiment includes the steps of: forming a body by processing a stainless steel material; forming a lid by processing a plated steel material having a Ni-based plating layer on the surface of a base steel material; and joining the lid and the body by welding.

[0078] (Lid forming process) The lid 10 is formed by processing a plated steel material having a Ni-based plating layer on the surface of the base steel material into a predetermined shape. As described in the above embodiment, the lid 10 may have a raised portion 11 and a rim portion 12, or the rim portion 12 may be provided on the outer periphery.

[0079] (Process for forming the body) The body 20 is formed by processing a stainless steel material. Examples of processing include deep drawing and welding. Deep drawing is performed by press-forming, for example, a single piece of stainless steel plate, to form the body 20 having the side surface 20a, the side surface 20b, the side surface 20c, the side surface 20d, and the bottom surface 20e described in the above embodiment. When steel material is processed by deep drawing, the body 20 is made of a single piece of steel material (for example, a steel plate), and therefore no welds are present on the side surface 20a, the side surface 20b, the side surface 20c, the side surface 20d, and the bottom surface 20e.

[0080] In the welding process, for example, stainless steel plates that will become side surface 20a, side surface 20b, side surface 20c, side surface 20d, and bottom surface 20e are prepared and welded together to form fuselage 20. Alternatively, a single steel plate may be bent to form side surface 20a, side surface 20b, side surface 20c, side surface 20d, and bottom surface 20e, and then these ends may be joined together to form fuselage 20. Note that the weld metal contained in the weld between stainless steel materials has excellent corrosion resistance and does not need to meet the composition requirements of weld metal 30. Alternatively, a single steel plate may be bent into a cylindrical shape, and laser welding may be performed to join the ends of the steel plate together with weld metal 31 to produce a cylindrical intermediate material, and this cylindrical intermediate material may be expanded into a rectangular shape to form fuselage 20.

[0081] When a stainless steel material is processed into the body 20, welding is preferably used for processing the body 20. Since stainless steel material has lower formability than plated steel material, welding makes it easier to process into a predetermined shape.

[0082] (Joining Step) In the joining step, the lid body 10 and the body 20 are joined by laser welding. In the laser welding, as long as appropriate welding can be performed, for example, the laser beam may be irradiated from any of the directions indicated by arrows A to F in the figure.

[0083] [Method 3B for manufacturing a sealed can body] When manufacturing a sealed can body 1 including a lid body 10, a body body 20, and a bottom lid 40 as shown in FIG. 2, the process for forming the body body 20 is different from the method 3A for manufacturing a sealed can body described above.

[0084] For example, the body 20 having the opening 21 may be formed from a stainless steel material by deep drawing as described above, and the bottom surface may be cut away to form the opening 22. Alternatively, the side surfaces 20a, 20b, 20c, and 20d may be formed by bending a single steel plate in the same direction. In this case, the ends of the bent steel plate may be joined by caulking or welding. Alternatively, the body 20 having the side surfaces 20a, 20b, 20c, and 20d may be formed by joining a plurality of steel plates.

[0085] The bottom cover 40 may be manufactured by the same process as the cover 10. In the joining process, the joining of the bottom cover 40 and the body 20 may be performed under the same conditions as the joining of the cover 10 and the body 20.

[0086] The sealed can body according to the above-described embodiment can be preferably used as a battery case or a battery cell case. In particular, the sealed can body according to the above-described embodiment can be preferably used as a prismatic lithium-ion battery cell case. The battery cell case is a case for accommodating battery cells. A battery cell is the smallest unit of a battery in a battery module. A battery module is formed by electrically connecting multiple battery cells. A battery pack can also be formed by further electrically connecting multiple battery modules. A battery pack can also be formed by electrically connecting multiple battery cells without forming a battery module. A battery module or battery pack is 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 multiple battery cells in an electric vehicle without forming a module or pack.

[0087] When the sealed can body according to the embodiment is used as a battery cell case, the sealed can body accommodates a positive electrode active material, a separator, a negative electrode active material, and an electrolyte. Furthermore, when the sealed can body according to the embodiment is used as a battery cell case, a positive electrode lead, a negative electrode lead, a positive electrode terminal, a negative electrode terminal, etc. may be further provided. The positive electrode lead, the negative electrode lead, the positive electrode terminal, the negative electrode terminal, etc. may be provided on the lid body 10 and / or the bottom lid 40. Alternatively, the positive electrode lead, the negative electrode lead, the positive electrode terminal, the negative electrode terminal, etc. may be provided on the body 20. When the sealed can body according to the embodiment is used as a battery cell case, it may be a negative electrode case in which the battery cell case main body serves as the negative electrode terminal. When the sealed can body according to the embodiment is used as a battery cell case, it may be a neutral case insulated from the positive electrode terminal and the negative electrode terminal. Furthermore, the lid body 10, the bottom lid 40, and the body 20 may be provided with holes for attaching a safety valve, an electrolyte inlet, electrodes, etc. In this case, by providing holes in the portion made of stainless steel, corrosion resistance of the holes can be ensured.

[0088] The invention according to the present disclosure will be specifically described below using examples, but the invention according to the present disclosure is not limited thereto.

[0089] Example 1 In this example, a battery was produced using a sealed can body, in which a lid body and a body body were joined by laser welding, as a battery cell case, and its performance was evaluated.

[0090] In the following Example 1 or Example 2, the following steel sheets (base steel sheets) were prepared as the base materials (substrates) of the plated steel sheets: Aluminum-killed steel (manufactured by Nippon Steel Corporation) with a thickness of 0.3 mm, general cold-rolled steel SPCC (manufactured by Nippon Steel Corporation) with a thickness of 0.2 to 0.3 mm, and Nb-SULC steel (manufactured by Nippon Steel Corporation) with a thickness of 0.2 to 1.4 mm were prepared as materials for the body and the lid.

[0091] The above-mentioned base steel sheets were plated with Ni or Ni-W plating to obtain plated steel sheets for the body and lid. The plating conditions for each plating were as follows. The main constituent of the plating layer of the following two types of Ni plating was separately identified using the above-mentioned method, and it was confirmed that it was Ni.

[0092] [Ni-based plating] A Ni-based plating layer was formed on a bare steel sheet by electroplating using a plating bath having the following components. After plating, the sheet was subjected to heat treatment under the following conditions: Ni plating bath: Watts bath (pH = 3.0) containing 250 g / L of nickel sulfate, 50 g / L of nickel chloride, and 30 g / L of boric acid. Plating bath temperature: 50°C. Current density: 20 A / dm2. Heat treatment conditions: 750 to 800°C x 20 seconds.

[0093] [Ni—W-based plating] Using the above Ni plating bath and the Ni—W alloy plating bath shown below, the base steel sheet was electroplated with Ni and then with Ni—W alloy plating to form a Ni—W-based plating layer. After plating, the steel sheet was subjected to heat treatment under the following conditions: Ni—W alloy plating bath: 65 g / L sodium tungstate, 50 g / L nickel sulfate, 100 g / L diammonium hydrogen citrate, 13 g / L sodium formate, plating bath temperature: 50°C, current density: 20 A / dm2, heat treatment conditions: 750 to 800°C x 20 seconds

[0094] In Example 1, the bodies of sealed can bodies were produced by deep drawing using each of the plated steel sheets shown in Table 1. For the bodies of sealed can bodies in which cracks were found after forming in the formability evaluation described below, the bodies were re-produced by press working and laser welding, and subjected to the elution test described below. Filler P shown in Table 3 was used during laser welding of the bodies. The filler was supplied at half the welding speed. The formed shape of the body was equivalent to a size of PHEV2 according to the DIN standard (depth: 91 mm, width: 26.5 mm, depth: 148 mm). Table 1 also shows the chemical compositions of the base steel sheets of the plated steel sheets (the balance including Fe and impurities).

[0095]

[0096] S-Ni is a plating layer with an Fe-Ni alloy layer between the Ni-based plating layer and the base steel, while Ni-W is a plating layer with an Ni-W-based plating layer on top of S-Ni.

[0097] Furthermore, lids for sealed can bodies were produced using the stainless steel sheets shown in Table 2. The lids were formed into any of joint shapes 1 to 3 and then joined to the body. The balance of the chemical composition in Table 2 includes Fe and impurities.

[0098]

[0099] Using the above-mentioned lids and bodies, sealed cans were produced in the combinations shown in Tables 4 and 5. A battery was housed inside the sealed can to produce a battery cell case. The battery was produced as follows.

[0100] (Battery Fabrication) ・Positive Electrode Plate Lithium cobalt oxide was used as the positive electrode active material. This was mixed with acetylene black and polyvinylidene fluoride (PVDF) in a mass ratio of 10:10:1, then applied as an aqueous dispersion to Al foil and dried. This was rolled to a predetermined thickness and cut to a predetermined size to form the positive electrode plate. ・Negative Electrode Plate Amorphous carbon was used as the negative electrode active material. This was dry-mixed with acetylene black, a conductive material, and N-methyl-2-pyrrolidone (NMP) in which polyvinylidene fluoride had been dissolved was uniformly dispersed in the mixture to create a paste with a mass ratio of carbon:acetylene black:PVDF = 88:5:7. This was applied to Cu foil, dried, rolled to a predetermined thickness, and cut to a predetermined size to form the negative electrode plate. ・Separator A polyethylene microporous membrane was used as the separator. Electrolyte The electrolyte used was a solution in which ethylene carbonate and diethyl carbonate were mixed in a volume ratio of 1:1 to which 1 mol / L of lithium hexafluorophosphate was added (1M-LiPF6 EC / DEC (1 / 1)).

[0101] The electrode group, which was made by sandwiching a separator between positive and negative plates and winding them, was crushed into a shape that would fit into the body of a battery cell case (sealed can), and the positive plate was welded to an Al lead, and the negative plate was welded to a Ni lead. The Al lead was welded to the positive electrode terminal attached to the lid, and the Ni lead was welded to the negative electrode terminal attached to the lid.

[0102] The lid was laser welded to the body. In some experimental examples, the filler shown in Table 3 was used during laser welding. The remainder of the chemical composition in Table 3 includes Fe and impurities. The filler was supplied at half the welding speed.

[0103]

[0104] The inside of the battery was dried in an atmosphere with a dew point of -76°C to remove moisture. In the same atmosphere, the above electrolyte was injected through the inlet. The battery was charged at 3.6 to 4.2 V in the same atmosphere. This procedure electrolytically removed any moisture remaining in the battery. The inlet was then closed with a plug.

[0105] The laser welding conditions for the lid and body were adjusted as follows to obtain a penetration depth equivalent to the plate thickness of the lid: Continuous wave, Output: 0.8 to 4.0 kW, Speed: 2.0 to 5.0 m / min, Focus offset: 0 to 10 mm (focus diameter during JF: 0.6 mm), Shielding gas: Ar.

[0106] The following evaluations were carried out on each of the obtained sealed can bodies, and the results are shown in Tables 4 and 5.

[0107] (Composition of Weld Metal) The average Cr content and the average Ni content of the weld metal were measured by the following method. The weld metal was cut out from the case to obtain a weld metal sample. Using an optical emission spectrometer (Shimadzu Corporation: ICPS-8100), measurements of this component were performed at five points, and the arithmetic mean value was taken as the average Cr content or the average Ni content.

[0108] When the average Cr content of the weld metal is [Cr] and the average Ni content is [Ni], the value of [Cr] + 4 × [Ni] (Equation 1) was taken as the corrosion resistance index.

[0109] (Formability) The body used for each sealing can body was observed before the battery cell case was produced. If the body could be formed from the steel plate without wrinkles or cracks, it was rated as ◯ (Good), and if cracks were observed after the body was formed, it was rated as × (Bad).

[0110] (Elution Test) After sealing the inlet, the battery cell case was held at 80°C for 750 hours. After holding, part of the battery cell case was disassembled in an atmosphere with a dew point of -76°C, and the electrolyte was collected using a pipette or the like. The amount of metal elution in the electrolyte was analyzed using an ICP-MS (model number: Agilent 7700x manufactured by Agilent Technologies Inc.). If the Fe component in the solution was 50 ppm or less, it was rated as Excellent (◎); if it was more than 50 ppm and less than 75 ppm, it was rated as Good (○); and if it was more than 75 ppm, it was rated as Bad (×).

[0111]

[0112]

[0113] As can be seen from the results in Tables 4 and 5, in the examples that met the requirements of the present application, the amount of Fe component dissolved into the solution was a trace amount of 75 ppm or less, and the formability of the fuselage was also good.

[0114] Example 2 In this example, a battery was produced using a sealed can body, in which a lid and a body were joined by laser welding, as a battery cell case, and its performance was evaluated.

[0115] In Example 2, a body of a sealed can was produced by press working and welding using each stainless steel sheet shown in Table 2. The formed shape of the body was equivalent to the size of PHEV2 according to the DIN standard (depth: 91 mm, width: 26.5 mm, depth: 148 mm). In addition, a lid of a sealed can was produced using each plated steel sheet shown in Table 1. The shape of the lid was formed into one of joint shapes 1, 2, or 4, and then joined to the body.

[0116] Using the above-mentioned lids and bodies, sealed cans were produced in the combinations shown in Tables 6 and 7. A battery was housed inside the sealed can to produce a battery cell case. The battery production conditions were the same as those for the battery of Example 1.

[0117] Each of the obtained sealed can bodies was evaluated for the composition of the weld metal and subjected to an elution test in the same manner as in Example 1. The results are shown in Tables 6 and 7.

[0118]

[0119]

[0120] As can be seen from the results in Tables 6 and 7, in the examples that met the requirements of the present application, only a small amount of Fe component dissolved into the solution.

[0121] The laser-welded joints of the sealed can body according to the present disclosure and the battery cell case using the sealed can body according to the present disclosure have high corrosion resistance. Furthermore, the method for manufacturing the sealed can body according to the present disclosure can provide a sealed can body having highly corrosion-resistant laser-welded joints. Therefore, the present invention is extremely useful industrially.

[0122] REFERENCE SIGNS LIST 1 Sealed can body 10 Lid body 20 Body 30, 31 Welded metal 40 Bottom lid

Claims

1. A sealed can body comprising a lid, a body, and a weld metal joining the lid and the body, wherein the lid is made of stainless steel, the body is made of plated steel having a Ni-based plating layer on the surface of the base steel, and wherein, when the average Cr content of the weld metal is [Cr] and the average Ni content of the weld metal is [Ni], the relationship [Cr] + 4 × [Ni] ≧ 5.0 is satisfied.

2. The sealed can body according to claim 1, characterized in that there are no welds in the body.

3. A sealed can body comprising a lid, a body, and a weld metal joining the lid and the body, wherein the lid is made of plated steel having a Ni-based plating layer on the surface of the base steel, the body is made of stainless steel, and wherein, when the average Cr content of the weld metal is [Cr] and the average Ni content of the weld metal is [Ni], the relationship [Cr] + 4 × [Ni] ≧ 5.0 is satisfied.

4. The sealed can body according to claim 3, characterized in that a weld is present in the body.

5. A sealed can body according to any one of claims 1 to 4, characterized in that the C content of the base steel material is more than 0 and 0.07 mass% or less.

6. A sealed can body according to any one of claims 1 to 4, characterized in that the stainless steel material has a thickness of 0.1 to 1.4 mm, and the plated steel material has a thickness of 0.1 to 1.4 mm.

7. The sealed can body according to any one of claims 1 to 4, characterized in that the Ni-based plating layer has a thickness of 0.3 to 10 μm.

8. The sealed can body according to any one of claims 1 to 4, characterized in that an Fe-Ni alloy layer is provided between the Ni-based plating layer and the base steel material.

9. A sealed can body according to any one of claims 3 or 4, further comprising a bottom lid provided opposite said lid body, and at least one of said lid body and said bottom lid being made of plated steel having a Ni-based plating layer on a surface of a base steel material.

10. A battery cell case using the sealed can body according to any one of claims 1 to 4.

11. A method for manufacturing a sealed can body including a lid, a body, and a weld metal joining the lid and the body, comprising: a step of processing a stainless steel material to form the lid; a step of processing a plated steel material having a Ni-based plating layer on the surface of a base steel material to form the body; and a step of joining the lid and the body by welding, wherein, when the average Cr content of the weld metal is [Cr] and the average Ni content of the weld metal is [Ni], the relationship [Cr] + 4 × [Ni] ≧ 5.0 is satisfied.

12. The method for manufacturing a sealed can body according to claim 11, characterized in that the processing of the body is a deep drawing process.

13. A method for manufacturing a sealed can body including a lid, a body, and a weld metal joining the lid and the body, comprising the steps of: processing a stainless steel material to form the lid; processing a non-plated steel material to form the body; providing a Ni-based plating layer on the surface of the body; and joining the lid and the body by welding, wherein when the average Cr content of the weld metal is [Cr] and the average Ni content of the weld metal is [Ni], the relationship [Cr] + 4 × [Ni] ≧ 5.0 is satisfied.

14. A method for manufacturing a sealed can body including a lid, a body, and a weld metal joining the lid and the body, comprising: a step of processing a stainless steel material to form the body; a step of processing a plated steel material having a Ni-based plating layer on the surface of a base steel material to form the lid; and a step of joining the lid and the body by welding, wherein, when the average Cr content of the weld metal is [Cr] and the average Ni content of the weld metal is [Ni], the relationship [Cr] + 4 × [Ni] ≧ 5.0 is satisfied.

15. The method for manufacturing a sealed can body according to claim 14, characterized in that the processing of the body is a welding process.

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