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

Abstract

The present invention provides a battery case with high electrolyte resistance, a battery, and a method for manufacturing the battery case. [Solution] A battery case comprising a lid 11, a body 12, and at least one weld metal 30, wherein the lid 11 and the body 12 each comprise a Ni-plated steel material having a base steel material and a Ni-based plating layer, and the battery case 1 is characterized in that when the average Cr content of the weld metal 30 is [Cr] and the average Ni content of the weld metal 30 is [Ni], the condition [Cr] + 4 × [Ni] ≥ 5.00 is satisfied.

Description

[Technical Field]

[0001] This invention relates to a battery case, a battery, and a method for manufacturing a battery case. [Background technology]

[0002] Lithium-ion batteries are widely used as batteries for electric vehicles. The battery cases that make up lithium-ion batteries come in various shapes, such as cylindrical, rectangular, and pouch-type. Of these, rectangular battery cases are often made of aluminum, as described in Patent Document 1. For example, Patent Document 1 discloses an aluminum can for secondary batteries, assembled by laser welding a lid and an outer casing made of aluminum alloy plates, and a method for manufacturing the same.

[0003] Furthermore, battery cases for lithium-ion batteries include those made of stainless steel and those made of plated steel. For example, Patent Document 2 discloses a rectangular sealed container for a rectangular battery in which a lid plate made of metal sheet is fitted into a rectangular opening formed at one end of a metal case, and the fitting portion is laser-welded. Ni (nickel) plated steel sheet is used as the material for this case. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2013-097900 [Patent Document 2] Japanese Patent Publication No. 08-315788 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The rectangular battery cases described above are often assembled by laser welding the top cover (lid) and the body. However, in battery cases using plated steel sheets, the laser-welded joints are less likely to exhibit improved corrosion resistance (resistance to electrolytes) compared to the base material that makes up the plated top cover and body. Therefore, under extremely harsh conditions, there is a possibility that the welded joints on the inner surface of the battery case may corrode. Furthermore, it is difficult to apply corrosion-resistant treatment to the inner surface of the welded joints after the top cover and body of the battery case have been laser-welded.

[0006] The present invention has been made in view of the above, and aims to provide a battery case with high resistance to electrolytes and a method for manufacturing a battery case. [Means for solving the problem]

[0007] (1) A battery case relating to one aspect of the present application is: A battery case comprising a lid, a body, and at least one weld metal, The lid and the body each include a base steel material and a Ni-plated steel material having a Ni-based plating layer. When the average Cr content of the weld metal is [Cr] and the average Ni content of the weld metal is [Ni], the following conditions are met: [Cr] + 4 × [Ni] ≥ 5.00. It is characterized by the following: (2) In the battery case described in (1) above, The fuselage does not have any welded parts containing the weld metal. The lid and the body may be joined together via the weld metal. (3) In the battery case described in (2) above, The carbon content of the raw steel material of the fuselage may be greater than 0% by mass and less than or equal to 0.070% by mass. (4) In the battery case described in (1) above, The fuselage has a welded section containing the weld metal, The lid and the body may be joined together via the weld metal. (5) In the battery case described in (1) above, The fuselage has a welded section containing the weld metal, The lid and the body may be joined by crimping. (6) In the battery case described in any one of the above items (1) to (5), The length of the body in the direction perpendicular to the lid may be 1.5 times or more the length of the lid in the longitudinal direction. (7) In the battery case described in any one of the above items (1) to (6), The thickness of the Ni-plated steel material may be 0.1 to 1.4 mm. (8) In the battery case described in any one of the above items (1) to (7), The thickness of the Ni-based plating layer may be 0.1 to 10.0 μm. (9) In the battery case described in any one of the above items (1) to (8), The basis weight of the aforementioned Ni-based plating layer is 2.0 to 89.0 g / m². 2 That's fine. (10) In the battery case described in any one of the above items (1) to (9), An Fe-Ni alloy layer may be present between the Ni-based plating layer and the base steel material. (11) In the battery case described in any one of the above items (1) to (10), The excess height of the weld metal may be 50% or less of the plate thickness of the Ni-plated steel material. (12) The battery case described in any one of the above items (1) to (11) is: A neutral can is also acceptable. (13) A battery according to one aspect of the present invention is a battery comprising the battery case described in any one of the above paragraphs (1) to (12). (14) A method for manufacturing a battery case according to one aspect of the present application is: A method for manufacturing a battery case, comprising a lid, a body, and at least one weld metal, A lid forming step involves processing a plated steel material having a base steel material and a Ni-based plating layer to form the lid, A fuselage forming step involves processing a plated steel material having a base steel material and a Ni-based plating layer to form the fuselage, A joining step of joining the lid body and the body, including, when the average Cr amount of the weld metal is [Cr] and the average Ni amount of the weld metal is [Ni], [Cr] + 4×[Ni] ≥ 5.00 is satisfied, which is characterized by this. (15) In the method for manufacturing a battery case according to (14) above, in the body forming step, the body is formed by deep drawing, in the joining step, the lid body and the body may be joined by welding. (16) In the method for manufacturing a battery case according to (14) above, in the body forming step, the body is formed by welding, in the joining step, the lid body and the body may be joined by welding. (17) In the method for manufacturing a battery case according to (14) above, in the body forming step, the body is formed by welding, in the joining step, the lid body and the body may be joined by winding. (18) In the method for manufacturing a battery case according to any one of (14) to (17) above, the weld metal may be formed using an austenitic filler wire. (19) In the method for manufacturing a battery case according to any one of (14) to (18) above, the weld metal is formed using a filler wire, and the supply speed of the filler wire may be 0.1 to 3.0 times the welding speed.

Effect of the Invention

[0008] The battery case according to the present invention and the battery using the battery case according to the present invention have high electrolyte resistance. Further, according to the method for manufacturing a battery case according to the present invention, a battery case with high electrolyte resistance can be provided.

Brief Description of the Drawings

[0009] [Figure 1] This is a schematic perspective view illustrating a battery case according to one embodiment of the present invention. [Figure 2] This is a schematic perspective view illustrating a battery case according to another embodiment of the present application. [Figure 3] This is a schematic cross-sectional view illustrating one embodiment of a welded joint. [Figure 4] This is a schematic cross-sectional view illustrating another embodiment of the welded joint. [Figure 5] This is a schematic cross-sectional view illustrating the structure of the crimping mechanism. [Figure 6] This is a schematic perspective view illustrating a modified example of a battery case according to one embodiment of the present invention. [Figure 7] This figure illustrates an example of welding of the lid and body of a battery case near the welded area according to one embodiment of the present application, and is a schematic cross-sectional view of the battery case in a plane perpendicular to the weld line. [Figure 8] This figure illustrates another example of welding of the lid and body near the weld of a battery case according to one embodiment of the present application, and is a schematic cross-sectional view of the battery case in a plane perpendicular to the weld line. [Figure 9] This figure illustrates an example of a method for manufacturing a battery case according to one embodiment of the present invention. [Figure 10] This figure illustrates another example of a method for manufacturing a battery case according to one embodiment of the present invention. [Modes for carrying out the invention]

[0010] The embodiments of the present invention will be described below with reference to examples, but it is obvious that the present invention is not limited to the examples described below. In the following description, specific numerical values ​​and materials may be given as examples, but other numerical values ​​and materials may be applied as long as the effects of the present invention are obtained. In addition, each component of the following embodiments can be combined with one another. Furthermore, in this specification, numerical ranges represented using "~" mean a range that includes the numbers written before and after "~" as the lower and upper limits, respectively. In this specification, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes, as long as their intended purpose is achieved.

[0011] In the following embodiments, the term "steel material" includes steel plates, parts obtained by machining steel plates into shapes other than flat plates, and steel plates formed by joining different types of steel plates together. The battery case has a sealed structure to prevent the contents, such as electrolyte, contained within the case from leaking out.

[0012] <Embodiment 1> First, Figure 1 shows an example of a battery case 1 according to this embodiment.

[0013] [Battery case] The battery case 1 shown in Figure 1 includes a lid 11, a body 12, and weld metal 30. The battery case 1 shown in Figure 1 has a body 12 manufactured by deep drawing, which will be described later. Therefore, there are no welds on the body 12. In addition, the sides (12a, 12b, 12c and side 12d) and bottom surface 12e of the body 12 are formed by deep drawing. Since there are no welds on the body 12 of such a battery case 1, it has the advantage of having excellent corrosion resistance without requiring any special treatment of the body 12.

[0014] [Lid] The lid 11 is joined to the body 12 to form the battery case 1. The material that makes up the lid 11 is nickel-plated steel, which has a nickel-based plating layer on the surface of the base steel material, as will be described later.

[0015] The lid 11 may be made of, for example, a single Ni-plated steel sheet. The lid 11 may be provided with an inlet for pouring electrolyte after sealing the battery case 1, holes for passing electrodes, notches, protrusions, recesses, etc. In the example shown in Figure 1, the lid 11 is connected to the opening 15 of the body 12, which will be described later, and is positioned to face the bottom surface 12e.

[0016] Note that the X, Y, and Z coordinate axes in Figures 1 and 2 are orthogonal to each other. In the example in Figure 1, the surface of the lid 11 is parallel to the X and Y coordinate axes, but this is not the only example.

[0017] [body] As illustrated in Figure 1, the fuselage 12 is composed of opposing sides 12a and 12b, opposing sides 12c and 12d, and a bottom surface 12e. Each of the sides 12a, 12b, 12c, and 12d is connected at one end to each end of the bottom surface 12e and is configured to rise from the bottom surface 12e. The surfaces of each of the sides 12a, 12b, 12c, and 12d intersect with the surface of the bottom surface 12e. In the example shown in Figure 1, the base surface 12e is parallel to the X and Y coordinate axes, and the sides 12a, 12b, 12c, and 12d are parallel to the Z coordinate axis, but this is not limited to the example shown.

[0018] One end of side surface 12a, which extends in a direction intersecting the base surface 12e, is connected to the end of side surface 12c, and the other end is connected to the end of side surface 12d. One end of side surface 12b, which extends in a direction intersecting the base surface 12e, is connected to the end of side surface 12c, and the other end is connected to the end of side surface 12d. In the example in Figure 1, sides 12a and 12b are parallel to the Y and Z coordinate axes, and sides 12c and 12d are parallel to the X and Z coordinate axes. Also, in the example in Figure 1, each end connecting sides 12a, 12b, 12c, and 12d is parallel to the Z coordinate axis.

[0019] The fuselage 12 has an opening 15. The opening 15 is formed by the ends of each of the sides 12a, 12b, 12c, and 12d: the end connected to the bottom surface 12e and the end located on the opposite side of each side. The lid 11 is joined to the fuselage 12 by weld metal 30, which will be described later, so as to close this opening 15.

[0020] As described above, since the battery case 1 is sealed, it is preferable that the outer shape of the lid 11 (end face of the lid 11) and the inner or outer shape of the opening 15 of the body 12 are the same shape. The inner shape of the opening 15 of the body 12 means the shape corresponding to the inner surface shape of the body 12 at the opening 15. Also, the outer shape of the opening 15 of the body 12 means the shape corresponding to the outer surface shape of the body 12 at the opening 15.

[0021] The material constituting the fuselage 12 is a nickel-plated steel material having a nickel-based plating layer on the surface of the base steel material, as will be described later. The fuselage 12 may be made of, for example, a single nickel-plated steel sheet.

[0022] [Weld metal] In the battery case 1 shown in Figure 1, a welded portion including weld metal 30 is formed around the entire circumference of the connection between the lid 11 and the body 12. The connection is the point where the lid 11 and the body 12 meet. However, the weld metal 30 does not necessarily need to join the lid 11 and the body 12 over the entire range of the connection; as long as the battery case 1 can be sealed, the weld metal 30 may join the lid 11 and the body 12 in only a part of the connection. In addition, a raised portion is provided on the outer circumference of the lid 11, rising from the plate surface of the lid 11, and this raised portion may be joined to the body 12.

[0023] In the battery case 1 of this embodiment, when the average amount of Cr in the weld metal 30 is [Cr] and the average amount of Ni is [Ni], the [Cr] + 4 × [Ni] (corrosion resistance index) is 5.00 or higher. The average Cr content of the weld metal 30 is measured using ICP (Inductively Coupled Plasma) emission spectroscopy. The Cr content at five arbitrary points in the weld metal is measured by ICP, and the arithmetic mean of these values ​​is taken as the average Cr content. The measurement points can be any part of the weld metal excluding the end portion. The end portion of the weld metal is recessed compared to the steady portion excluding the end portion, so the end portion can be identified by its appearance. The average Ni content in the weld metal is calculated using the same method as the average Cr content.

[0024] Weld metal 30 is the part of the weld where filler, steel, etc., melt and solidify due to irradiation with a laser beam during laser welding. It is a part of the weld and is the metal that melted and solidified during welding. When filler is used during laser welding, the source of material for weld metal 30 is the multiple steel materials being joined and the filler. If the steel material is plated, the components of the plating also melt and become part of the material that makes up the weld metal. In addition to elements from these sources, oxygen and nitrogen from the air are incorporated into the weld metal 30, and unavoidable impurities may also be incorporated.

[0025] In the weld metal 30 of the battery case 1 according to this embodiment, the electrolyte resistance of the weld metal 30 can be improved by having a [Cr] + 4 × [Ni] (corrosion resistance index) of 5.00 or higher.

[0026] In the battery case 1 illustrated in Figure 1, the weld metal 30 extends continuously along the X and Y coordinate axes and is formed around the entire circumference of the opening 15 of the body 12, but the form of the weld metal 30 is not limited to this.

[0027] [Ni-plated steel] The Ni-plated steel used for the lid 10 and body 12 is a steel material having a Ni-based plating layer on the surface of the base steel material. The chemical composition of the base steel material is as follows: C (carbon): more than 0 and 0.150% by mass or less, Si (silicon): greater than 0 and less than 0.800% by mass, Mn (manganese): greater than 0 and less than or equal to 1.00 mass%, P (phosphorus): more than 0 and 0.05% by mass or less, S (sulfur): more than 0 and 0.050% by mass or less, Mo (Molybdenum): 0-0.300 mass%, Cu (copper): 0~1.00% by mass, Ti (Titanium): 0-0.100 mass%, Al (aluminum): 0-0.10% by mass, Co (cobalt): 0-1,000 mass%, Nb (niobium): 0-0.100 mass%, N (nitrogen): 0~0.030% by mass, Sn (tin): 0~0.100% by mass, Cr (chromium): 0-0.40 mass%, Ni (nickel): 0-1.0000 mass%, B (Boron): 0-0.0100% by mass, Mg (Magnesium): 0-0.0500 mass%, Zr (Zirconium): 0-0.5% by mass, W (Tungsten): 0-0.200 mass%, Ca+REM: 0~0.1% by mass, Preferably, it contains [a certain component], with the remainder being Fe (iron) and impurities. Impurities refer to components contained in the raw materials or components that are introduced during the manufacturing process and are not intentionally included. Steel sheets with such a chemical composition are preferable in that they have excellent formability.

[0028] The chemical composition of the base steel material for plated steel materials is measured using ICP (Inductively Coupled Plasma) emission spectrometry in accordance with JIS G 1258-1:2014. However, carbon (C), sulfur (S), and nitrogen (N) are measured by well-known gas analysis methods.

[0029] The carbon content of the base steel material (substrate) is more preferably greater than 0 and less than or equal to 0.070% by mass. This has the advantage of further improving the formability of the nickel-plated steel material.

[0030] A nickel-based plating layer is provided on the surface of the base steel material that constitutes nickel-plated steel. A nickel-based plating layer is a plating layer whose main component is nickel. Specifically, the nickel-based plating layer is defined as the range in which the nickel concentration is 80% by mass or more when measured using GDS (Glow discharge optical emission spectrometry).

[0031] From the viewpoint of corrosion resistance, the chemical composition of the Ni-based plating layer is more preferably Ni: 50-95% by mass, Fe: 5-50% by mass, and a layer consisting of impurities. The chemical composition of the Ni-based plating layer can be measured by GDS. The Ni-based plating layer may also contain a total of 30% by mass or less of one or more alloying elements from Co, Sn, Zn, W, Mo, or Cr.

[0032] A thickness of 0.1 to 10.0 μm is more preferable for the Ni-based plating layer. Increasing the thickness of the Ni-based plating layer improves electrolyte resistance but also increases costs. A thickness of 0.1 to 10.0 μm for the Ni-based plating layer offers the advantage of a good balance between electrolyte resistance and cost. The thickness of the Ni-based plating layer can be measured using GDS. Using GDS, the thickness of five arbitrary points on the plating layer is measured, and the arithmetic mean of these measurements is taken as the thickness of the Ni-based plating layer.

[0033] The basis weight of the Ni-based plating layer is 2.0 to 89.0 g / m². 2 Alternatively, the basis weight of the Ni-based plating layer is measured by ICP emission spectrometry (ICP-OES). To measure the basis weight, first, a predetermined area of ​​the Ni-based plating layer is dissolved in acid. Next, the total amount of Ni contained in the solution is quantitatively analyzed by ICP-OES. By dividing the total amount of Ni quantified by ICP-OES by the predetermined area, the basis weight per unit area can be determined. This makes it possible to improve the corrosion resistance of the base steel sheet while suppressing the cost increase caused by Ni plating.

[0034] An Fe-Ni alloy layer may be present between the Ni-based plating layer and the base steel material. The Fe-Ni alloy layer has a Ni concentration of 10% by mass or more and less than 80% by mass. The presence of the Fe-Ni alloy layer improves corrosion resistance and formability. The Fe-Ni alloy layer can be measured by GDS. Furthermore, the Ni-based plating layer of the Ni-plated steel sheet may be an alloyed plating layer that is alloyed with the base steel sheet. In this case, the Ni-based plating layer may be a fully diffused plating layer in which the Fe from the base steel sheet is diffused to its surface, or it may be a partially diffused plating layer in which the Fe from the base steel sheet is not diffused to its surface. On the other hand, the Ni-based plating layer may not be alloyed with the base steel sheet.

[0035] 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 GDS. Using GDS, the thickness of any five points on the cross-section of the Ni-plated steel material is measured, and the arithmetic mean of these measurements is taken as the thickness of the Fe-Ni alloy layer.

[0036] A Ni-W plating layer may be further provided on top of the Ni-based plating layer. Having a Ni-W plating layer on the surface improves corrosion resistance and formability. The Ni-W plating layer is defined as the range in which the W concentration is 10% by mass or more when measured using GDS. The thickness of the Ni-W plating layer can be measured using GDS. The thickness is measured at five points using GDS, and the arithmetic mean of these measurements is taken as the thickness of the Ni-W plating layer.

[0037] The thickness of the plated steel is more preferably 0.1 to 1.4 mm. This has the advantage of producing a battery case that is lightweight and has excellent mechanical strength. The thickness of plated steel is determined by measuring the thickness at five points on a flat surface, excluding processed areas such as bent sections, using a micrometer, and taking the arithmetic mean of these measurements as the thickness of the plated steel.

[0038] Furthermore, in the Ni-plated steel material described above, various chemical conversion coating layers (not shown) may be present between the base steel material and the plating layer. The presence of such chemical conversion coating layers makes it possible to further improve the adhesion between the base steel material and the plating 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 material.

[0039] 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.

[0040] <Embodiment 2> Next, other embodiments of the battery case will be described with reference to Figure 2. In the battery case 2 according to this embodiment, the configuration of the battery case 1 according to Embodiment 1 can be appropriately adopted. The battery case 2 shown in Figure 2 includes a lid 21, a body 22, welded metal (31, 32), and a bottom cover 24. As will be described later, the battery case 2 shown in Figure 2 has a body 22 that is manufactured by bending and welding steel. Therefore, there are welded parts on the body 22.

[0041] The battery case 1 shown in Figure 1 and the battery case 2 shown in Figure 2 differ mainly in the configuration of their bodies. The body 22 of the battery case 2 is composed of opposing sides 22a and 22b, and opposing sides 22c and 22d, as illustrated in Figure 2. One end of side surface 22a, which extends in a direction intersecting the lid 21 and bottom lid 24, is connected to the end of side surface 22c, and the other end is connected to the end of side surface 22d. One end of side surface 22b, which extends in a direction intersecting the lid 21 and bottom lid 24, is connected to the end of side surface 22c, and the other end is connected to the end of side surface 22d.

[0042] In the example in Figure 2, the plate surfaces of the lid 21 and bottom lid 24 are parallel to the X and Y coordinate axes, and the sides 12a, 12b, 12c, and 12d are parallel to the Z coordinate axis, but this is not limited to the example. Also, in the example in Figure 21, the sides 22a and 22b are parallel to the Y and Z coordinate axes, and the sides 22c and 22d are parallel to the X and Z coordinate axes. Also, in the example in Figure 2, the ends connecting the sides 22a, 22b, 22c, and 22d are parallel to the Z coordinate axis.

[0043] As shown in Figure 2, the body 22 has an opening 25. The body 22 also has an opening 26 located on the opposite side of each side from the opening 25. The cover 21 is joined to the body 22 so as to close the opening 25 with weld metal 32, which will be described later, and the bottom cover 24 is joined to the body 22 so as to close the opening 26.

[0044] As described above, since the battery case 2 is sealed, it is preferable that the outer shape of the lid 21 (end face of the lid 21) and the inner or outer shape of the opening 25 of the body 22 are the same shape. Also, it is preferable that the outer shape of the bottom lid 24 (end face of the bottom lid 24) and the inner or outer shape of the opening 26 of the body 22 are the same shape.

[0045] The lid 21 of the battery case 2 shown in Figure 2 can adopt the same configuration as the lid 11 of the battery case 1 shown in Figure 1 according to Embodiment 1, so its explanation is omitted here.

[0046] Furthermore, the bottom cover 24 can adopt the same configuration as the lid 21. The shape of the bottom cover 24 may also be the same as that of the lid 21. In the example shown in Figure 2, the bottom cover 24 is connected to an opening 26 provided on the opposite side of the opening 25 of the body 22, and the lid 21 and the bottom cover 24 are arranged so that their plate surfaces face each other.

[0047] A welded joint containing weld metal 31 is formed in the body 22 of the battery case 2. This welded joint joins the end faces of the Ni-plated steel material that makes up the body 22. As shown in Figure 2, the welded joint is formed along the Z coordinate axis, from the end on the opening 25 side to the end on the opening 26 side of the side surface 22a of the body 22.

[0048] Figure 3 shows a cross-sectional view of the battery case 2 taken from a plane perpendicular to the extension direction of the weld metal 31. Figure 3 is a cross-section perpendicular to the Z coordinate axis along line AA in Figure 2. As shown in Figure 3, the end faces of the Ni-plated steel materials constituting the body 22 are joined together by the weld metal 31. With this configuration, the base steel material of the Ni-plated steel is not exposed on the inner surface of the battery case 2 (the surface located on the inside side of the battery case and on the positive direction side of the X coordinate axis), thus ensuring electrolyte resistance on the inner surface of the battery case 2.

[0049] Furthermore, by having a corrosion resistance index of 5.00 or higher for the weld metal 31, the electrolyte resistance of the weld metal 31 can be improved.

[0050] The formation of a welded section containing the weld metal 31 on the side surface of the body 22 has the advantage of suppressing deformation of the Ni-plated steel material due to the thermal history during welding. In the example shown in Figure 2, the so-called weld bead formed by the weld metal 31 is formed in a straight line on the side surface 22a, but the weld bead may include curves or other shapes as long as the battery case 2 is sealed. Furthermore, the weld metal 31 may be formed on any side surface of the body 22 as long as the battery case 2 can be sealed, and the weld metal 30 may be formed across multiple sides.

[0051] In the example in Figure 2, the Ni-plated steel material is joined on the side surface 22a, but the weld is not limited to this, and the weld may be located at the end of the side surface. That is, the side surfaces may be joined together at their ends by the weld metal 31.

[0052] Figure 4 shows an example in which the sides are joined together by weld metal 31. Figure 4 is a cross-sectional view of the battery case 2 taken with a plane perpendicular to the extension direction of the weld metal 31. In the example in Figure 4, the end face of the side surface 22a and the plate surface of the side surface 22c that constitute the body 22 are joined together by weld metal 31. Even with this configuration, the base steel material of the Ni-plated steel is not exposed on the inner surface of the battery case 2 (the surface located on the inside side of the battery case and on the positive direction side of the X and Y coordinate axes), so the electrolyte resistance of the inner surface of the battery case 2 can be ensured. In this way, by joining the sides of the fuselage 22 at their ends, the amount of Ni-based plating components of the Ni-plated steel material that dissolve into the weld metal 31 increases, which has the advantage of forming a weld metal 31 with high corrosion resistance.

[0053] In battery case 2, the lid 21 and the body 22 and / or the bottom lid 24 and the body 22 may be joined by a weld, similar to battery case 1. In that case, the weld metal 32 provided at the weld between the lid 21 and / or the bottom lid 24 and the body 22 can have the same configuration as the weld metal 31 of battery case 1. Furthermore, the weld metal 31 or weld metal 32 in this embodiment can have the same configuration as the weld metal 30 described in Embodiment 1.

[0054] Alternatively, the lid 21 and the body 22, and the bottom lid 24 and the body 22 may be joined by crimping. Figure 5 shows an example of how the lid 21 and the body 22 are joined by crimping. Figure 5 illustrates a cross-sectional view of the end of the side surface 22a of the body 22 located on the lid 21 side, in a plane perpendicular to the direction of extension. As for the crimping structure, for example, a structure generally known as a double crimping structure can be adopted. The crimping does not necessarily need to join the lid 21 (or bottom lid 24) and the body 22 over the entire range of the connection; as long as the battery case 2 can be sealed, the joining by crimping may be applied to only a part of the connection. In addition, a rising portion is provided on the outer circumference of the lid 21 (or bottom lid 24) rising from the plate surface of the lid 21, and the rising portion may be joined to the body 22 by crimping.

[0055] In the battery case 2 according to this embodiment, the length L of the body 22 in the direction perpendicular to the lid 21 may be 1.5 times or more the length W of the lid 21 in the longitudinal direction. This has the advantage that even in a space with limited height, the lid 21 equipped with terminals can be positioned laterally to increase the battery's space utilization. For example, by using a battery with terminals on a laterally positioned lid 21 as the battery for an electric vehicle, the thickness of the electric vehicle's floor can be reduced, and the passenger space of the electric vehicle can be expanded.

[0056] Figure 6 illustrates a battery case 2 in which the length L of the body 22 in the direction perpendicular to the lid 21 is 1.5 times or more the length W of the lid 21 in the longitudinal direction. The direction perpendicular to the lid 21 means the direction perpendicular to the plate surface of the lid 21. In the example in Figure 6, the length L of the body 22 in the direction perpendicular to the lid 21 is the length in the direction parallel to the Z coordinate axis of the body 22. The longitudinal length W of the lid 21 means the maximum length of the lid 21 in the direction parallel to the plate surface of the lid 21. In the example in Figure 6, the longitudinal length W of the lid 21 is the length in the direction parallel to the X coordinate axis of the lid 21.

[0057] In the above embodiment, the weld metal (30, 31, 32) may have a weld height of 50% or less of the thickness of the Ni-plated steel sheet. Weld metal refers to the portion that protrudes beyond the surface of the Ni-plated steel sheet, and its definition is as disclosed in JIS Z 3001. The weld metal (30, 31, 32) weld height is as disclosed in JASS 6-20011. The weld metal (30, 31, 32) weld height is determined by cutting out three cross-sections of the steady portion, excluding the end portion, observing these cross-sections, and taking the arithmetic mean of the measured values. The excess reinforcement height is 50% or less of the thickness of the Ni-plated steel sheet, preferably 30% or less, and more preferably 10% or less. This reduces the external dimensions and improves the battery loading efficiency. In addition, in the case of contact surfaces with cooling plates, the gap filler is reduced, which can lower manufacturing costs.

[0058] In the above embodiment, when the lids (11, 21) and / or bottom lid 24 and the body (12, 22) are joined by welding, the joint shape may be as follows.

[0059] (Joint shape 1) Figure 7 illustrates an example of the lid 40 and body 50 near the weld of the battery case 3. Figure 7 is a schematic cross-sectional view of the battery case 3 in a plane perpendicular to the direction of extension of the weld line of the weld metal 33. In the example shown in Figure 7, the lid 40 includes a raised portion 41 and an edge portion 42. The raised portion 41 and the edge portion 42 are provided along the outer circumference of the lid 40. By having such a raised portion 41 and edge portion 42, the edge portion 42 of the lid 40 engages with the opening 51 of the body 50, and the lid 40 can be supported.

[0060] As illustrated in Figure 7, the weld metal 33 is provided at the end of the body 50 on the opening 51 side and at least along the edge 42. The weld metal 33 may also extend up to the rising portion 41.

[0061] (Joint shape 2) Figure 8 illustrates another example of the lid 60 and body 70 near the weld of the battery case 4 according to this embodiment. Figure 8 is a schematic cross-sectional view of the battery case 1 in a plane perpendicular to the direction of extension of the weld line of the weld metal 34. In the example shown in Figure 8, the lid 60 is provided with a raised portion 61. The raised portion 61 is provided along the outer circumference of the lid 60. Having such a raised portion has the advantage that the cut end surface, where the plating protection of the plated steel is weak, is not exposed to the inner surface.

[0062] As illustrated in Figure 8, the weld metal 34 is provided along the end of the fuselage 70 on the opening 71 side and its vicinity, as well as across the rising portion 61.

[0063] For example, when using the battery case of this embodiment as a battery cell case to house lithium-ion battery cells in an electric vehicle, as illustrated in Figure 7 or Figure 8, the joint shape of the body does not protrude toward the outer surface of the body, which has the advantages of allowing the cell cases to be arranged without gaps and preventing interference with other parts.

[0064] The following describes a method for manufacturing a battery case according to the present invention. These manufacturing methods allow for the suitability of producing battery cases with high electrolyte resistance. However, it is obvious that battery cases obtained by methods other than those described below can also be considered as battery cases of the present invention, as long as they satisfy the requirements of the present invention.

[0065] <Embodiment 3> The method for manufacturing a battery case according to this embodiment includes a lid forming step of processing a plated steel material having a base steel material and a Ni-based plating layer to form a lid, a body forming step of processing a plated steel material having a base steel material and a Ni-based plating layer to form a body, and a joining step of joining the lid and the body. Furthermore, in the method for manufacturing a battery case according to this embodiment, when the average amount of Cr in the weld metal is [Cr] and the average amount of Ni in the weld metal is [Ni], the condition [Cr] + 4 × [Ni] ≥ 5.00 is satisfied.

[0066] The battery case manufacturing method according to this embodiment can be used to manufacture the battery case 1 according to Embodiment 1. Below, the manufacturing method for the battery case will be described using the steps for manufacturing the battery case 1 as an example.

[0067] (Lid formation process) The lid 11 is formed by processing Ni-plated steel into a predetermined shape. The outer circumference of the lid 11 may be provided with a raised portion or the like, as described in the above embodiment. The lid 11 may also have an inlet for injecting electrolyte after sealing the battery case 1, holes for passing electrodes, notches, protrusions, recesses, etc.

[0068] (Body formation process) In the battery case manufacturing method according to this embodiment, the body 12 is formed by deep drawing a plated steel material having a Ni-based plating layer on the surface of a base steel material. By deep drawing, a single plated steel sheet is press-formed to form the body 12 having the side surfaces 12a, 12b, 12c, 12d and bottom surface 12e as described in the above embodiment.

[0069] When steel is processed by deep drawing, the fuselage 12 is made of a single Ni-plated steel material (for example, Ni-plated steel sheet), and therefore there are no welds on the sides 12a, 12b, 12c, 12d and bottom 12e that make up the fuselage 12. Since there are no welds in the fuselage 12 formed by deep drawing, it has excellent electrolyte resistance without the need for special treatment (for example, post-weld plating, coating, or painting).

[0070] (Joining process) In the joining process, the lid 11 and the body 12 are joined by laser welding. Specifically, the lid 11 and the body 12 are positioned in predetermined locations, and a welded joint is formed around the entire circumference of the connection between the lid 11 and the body 12.

[0071] In laser welding, it is preferable to form the weld metal 30 using an austenitic filler wire. Using an austenitic filler wire has the advantage of improving corrosion resistance compared to using a ferritic filler wire.

[0072] The chemical composition of austenitic filler wires is as follows: C (carbon): more than 0 and 0.090% by mass or less, Si (silicon): 0% or less by mass, Mn (manganese): greater than 0 and less than or equal to 3.0% by mass. P (phosphorus): more than 0 and 0.05% by mass or less, S (sulfur): more than 0 and 0.050% by mass or less, Cr (chromium): 11.00~30.00 mass%, Ti (Titanium): 0 or less by mass, V (Vanadium): Greater than 0 and less than or equal to 0.10 mass%, W (Tungsten): Greater than 0% by mass and less than or equal to 0.20% by mass. Mo (Molybdenum): Greater than 0 and less than or equal to 5.00% by mass. Nb (niobium): more than 0 and 1.000% by mass or less, Ni (Nickel): 6.00~30.00 mass%, Cu (copper): more than 0 and less than 5.000% by mass, Sn (tin): more than 0 and 0.100% by mass or less, Co (cobalt): greater than 0 and less than 3,000 mass%, Al (aluminum): greater than 0 and less than 0.100% by mass, Mg (Magnesium): Greater than 0 and less than or equal to 0.0500 mass%, B (Boron): Greater than 0, less than or equal to 0.0100% by mass. N (nitrogen): more than 0 and 0.1000% by mass or less, It is preferable that the product contains more than 0% by mass of oxygen (O). Furthermore, the chemical composition of the filler wire may include As, Zr, Hf, Sb, Sr, or REM in an amount of 1.0% by mass or less. The chemical composition of the filler wire shall be measured using ICP (Inductively Coupled Plasma) emission spectroscopy in accordance with JIS G 1258-1:2014. However, carbon (C), sulfur (S), and nitrogen (N) shall be measured by well-known gas analysis methods.

[0073] In the joining process, the filler wire supply rate is preferably 0.1 to 3.0 times the welding rate. Too much filler results in excessive weld bead. Too little filler prevents proper corrosion resistance. Therefore, the filler wire supply rate should be 0.1 to 3.0 times the welding rate. More preferably, the filler wire supply rate should be 0.3 to 1 time the welding rate. If the welding speed is too slow, the cycle time will increase, leading to higher costs. If the welding speed is too fast, there will be a lot of spatter, which will increase the cost of spatter removal. Therefore, a welding speed of 0.5 to 20 m / min is ideal. More preferably, a welding speed of 2 to 10 m / min is preferable.

[0074] If the diameter of the filler wire is too thin, the tip of the wire may shake during welding, the laser light may not hit it, and the filler may remain unmelted. If the diameter of the filler wire is too thick, the heat capacity of the wire becomes large, and it may remain unmelted even when the laser light hits it. Therefore, the diameter of the filler wire is more preferably 0.6 to 2 mm in diameter. More preferably, the diameter of the filler wire is 0.8 to 1.2 mm in diameter.

[0075] The dilution rate of the Ni-plated steel sheet and the filler wire is the ratio of the volume of the filler in the volume of the weld metal. That is, the dilution rate can be expressed by the following formula. Dilution rate = Volume of filler (mm 3 / s) / Volume of weld metal (mm 3 / s) Here, each item is as follows. Volume of weld metal (mm 3 / s) = Volume of filler supplied (mm 3 / s) + Volume of steel sheet melted (mm 3 / s) Volume of filler supplied (mm 3 / s) = (Filler wire diameter (mm) / 2) 2 × π × Filler wire supply speed (mm / s) Supply speed ratio = Filler wire supply speed (mm / s) / Welding speed (mm / s)

[0076] By the above joining process, a weld metal 30 that joins the lid body 11 and the body 12 is formed. The weld metal 30 according to the present embodiment satisfies [Cr] + 4 × [Ni] ≧ 5.00 when the average Cr amount is [Cr] and the average Ni amount of the weld metal is [Ni]. Therefore, the electrolytic solution resistance of the weld metal 30 can be improved.

[0077] <Embodiment 4> The method for manufacturing a battery case according to this embodiment includes a lid forming step of processing a plated steel material having a base steel material and a Ni-based plating layer to form a lid, a body forming step of processing a plated steel material having a base steel material and a Ni-based plating layer to form a body, and a joining step of joining the lid and the body. Furthermore, in the method for manufacturing a battery case according to this embodiment, when the average amount of Cr in the weld metal is [Cr] and the average amount of Ni in the weld metal is [Ni], the condition [Cr] + 4 × [Ni] ≥ 5.00 is satisfied.

[0078] The battery case manufacturing method according to this embodiment can be used to manufacture the battery case 2 according to Embodiment 2. The following describes the process for manufacturing the battery case 2 as an example.

[0079] (Lid formation process) The lid 11 is formed by processing Ni-plated steel into a predetermined shape. The outer circumference of the lid 11 may be provided with a raised portion or the like, as described in the above embodiment. The lid 11 may also have an inlet for injecting electrolyte after sealing the battery case 1, holes for passing electrodes, notches, protrusions, recesses, etc.

[0080] (Body formation process) In the battery case manufacturing method according to this embodiment, a nickel-plated steel material having a nickel-based plating layer on the surface of a base steel material is bent, and the ends of the bent nickel-plated steel material are joined by laser welding to form the body 22. This forms the body 22 having sides 22a, 22b, 22c, and 22d as described in the above embodiment.

[0081] An example of the fuselage formation process is shown in Figure 9. For the bending process, a Ni-plated steel material S as shown in Figure 9(a) is bent into the shape shown in Figure 9(b) to obtain the shape shown in Figure 9(c). Then, the weld metal 31 is formed by laser welding to form the fuselage 22.

[0082] Another example of the fuselage formation process is shown in Figure 10. A Ni-plated steel material S, as shown in Figure 10(a), is bent into a cylindrical shape as shown in Figure 10(b), and the ends of the Ni-plated steel material are joined together by laser welding with weld metal 31. In this way, a cylindrical intermediate material is created as shown in Figure 10(b). Then, this cylindrical intermediate material is expanded into a rectangular shape to obtain the shape shown in Figure 10(c).

[0083] When the fuselage 22 is formed using the method described above, the fuselage 22 has at least one welded joint. When the body 22 is formed using the method described above, the radius of the corners of the body 22 can be made smaller compared to deep drawing. This has the advantage of increasing the volume of the battery case 2.

[0084] (Joining process) In the joining process, the lid 21 and the body 22 are joined by laser welding. Specifically, the lid 21 and the body 22 are positioned in predetermined locations, and a welded joint is formed around the entire circumference of the connection between the lid 21 and the body 22.

[0085] When laser welding is performed in the joining process, the specific configuration is the same as in Embodiment 4, so a description is omitted here. Furthermore, in the joining process, the bottom cover 24 and the body 22 are joined by laser welding. The joining of the bottom cover 24 and the body 22 may be carried out under the same conditions as the joining of the cover 21 and the body 22.

[0086] In the joining process, instead of laser welding, the lid 21 and the body 22, and / or the bottom lid 24 and the body 22, may be joined by crimping. As for the crimping method, a common double crimping method can be used. That is, the crimped structure can be formed by wrapping the portion near the end of the lid 11 around the portion near the end of the body 12 and pressing them together. With double crimping, the materials constituting the lid 11 and the materials constituting the body 12 overlap, creating a sealed structure.

[0087] The battery according to the above 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. Battery modules or battery packs are used, for example, as a power source for electric vehicles. However, the use of battery modules or battery packs in electric vehicles is not essential. It is also possible to mount a large number of battery cells in an electric vehicle without constructing a module or pack.

[0088] In other words, the battery case according to the above embodiment can be preferably used as a battery cell case. In particular, the battery case according to the above embodiment can be preferably used as a prismatic lithium-ion battery cell case. When used as a battery cell case, the case contains the positive electrode active material, separator, negative electrode active material, and electrolyte.

[0089] Furthermore, when the battery case according to the above embodiment is used as a battery cell case, positive lead, negative lead, positive terminal, negative terminal, etc. may be provided. When the battery case according to the embodiment is used as a battery cell case, the battery cell case body may be used as a negative terminal case. When the battery case according to the embodiment is used as a battery cell case, it may be a neutral case (neutral can) insulated from the positive terminal and negative terminal.

[0090] A battery case can be manufactured by the battery case manufacturing method according to the embodiment described above. [Examples]

[0091] The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.

[0092] In this example, a battery was created using a battery case in which the lid and body were joined by laser welding as the battery cell case, and its performance was evaluated.

[0093] In the following examples, the following steel sheets (base steel sheets) were prepared as the base material (substrate) for the Ni-plated steel sheets. For the lid and body, we prepared aluminum-killed steel with a plate thickness of 0.3 mm (manufactured by Nippon Steel Corporation, used for S6 in Table 1), general cold-rolled steel sheet SPCC with a plate thickness of 0.2 to 0.3 mm (manufactured by Nippon Steel Corporation, used for S4, S7, and S8 in Table 1), and Nb-SULC steel with a plate thickness of 0.2 to 1.4 mm (manufactured by Nippon Steel Corporation, used for S1 to S3, S5, and W1 in Table 1).

[0094] The above-mentioned base steel sheet was subjected to either a Ni-based plating or a Ni-W-based plating to produce Ni-plated steel sheets for use as the material for the lid and body. The plating conditions for each plating are as follows. Separately, the main constituent components of the plating layer for the following two types of Ni-based plating were identified using the method described above, and it was confirmed that they were Ni.

[0095] [Ni-based plating] A nickel-based plating layer was formed on a steel sheet by electroplating using a plating bath containing the following components. After plating, heat treatment was performed under the conditions described below. Ni plating bath: Watts bath containing 250 g / L nickel sulfate, 50 g / L nickel chloride, and 30 g / L boric acid (pH=3.0) Plating bath temperature: 50℃ Current density: 20A / dm 2 Heat treatment conditions: 750-800°C x 20 seconds

[0096] [Ni-W plating] Using the Ni plating bath described above and the Ni-W alloy plating bath described below, the base steel sheet was plated in the order of electroplating Ni followed by Ni-W alloy plating to form a Ni-W plating layer. After plating, heat treatment was performed under the conditions described below. Ni-W alloy plating bath: Sodium tungstate 65g / L, nickel sulfate 50g / L, diammonium hydrogen citrate 100g / L, sodium formate 13g / L Plating bath temperature: 50℃ Current density: 20A / dm 2 Heat treatment conditions: 750-800°C x 20 seconds

[0097] The battery case body was created by bending and welding each of the Ni-plated steel sheets shown in Table 1. The Ni-plated steel sheet before bending had dimensions of 240 mm x 300 mm. The formed shape of the body was 300 mm (depth) x 20 mm (width) x 100 mm (height). The opening of the body was 20 mm x 100 mm. Table 1 also shows the chemical composition of the base steel sheet for the Ni-plated steel sheet (the remainder being Fe and impurities).

[0098] In Table 1, the notation S-Ni in the plating type column means that the plating layer has an Fe-Ni alloy layer between the Ni-based plating layer and the base steel material. The notation Ni-W in the plating type column means that the plating layer has a Ni-W-based plating layer on top of the S-Ni layer.

[0099] The plating thickness was measured on both the front and back surfaces of the Ni-plated steel sheet using the method described in the above embodiment.

[0100] [Table 1]

[0101] For the bent nickel-plated steel sheets, the ends of the sheets were joined together by laser welding along the direction of the depth of the fuselage. The laser welding of the fuselage was adjusted to the following conditions to ensure complete penetration. Continuous wave Output: 0.8~6.0kW Speed: 0.5~20.0m / min Focus shift: 0-10mm (Gathering diameter with JF: 0.6mm) Shielding gas: Ar

[0102] A filler was used in the laser welding. The steel grade of the filler is shown in Table 2. The remainder of the chemical composition in Table 2 includes Fe and impurities.

[0103] [Table 2]

[0104] Each of the Ni-plated steel sheets shown in Table 1 was processed into the predetermined shape to create the battery case cover.

[0105] Using the above-mentioned lids and bodies, each battery case was created using the combinations of lids, bodies, and filler steel types shown in Tables 3A, 3B, 4A, and 4B. The battery was placed inside the battery case to create a battery cell case. The battery was created as follows:

[0106] (Battery construction) • Positive plate Lithium cobalt oxide was used as the positive electrode active material. Acetylene black and polyvinylidene fluoride (PVDF) were mixed with this in a mass ratio of 10:10:1, and then coated onto aluminum foil as an aqueous dispersion and dried. This was rolled to a predetermined thickness and cut to a predetermined size to form the positive electrode plate. • Negative plate Amorphous carbon was used as the negative electrode active material. This was dry-mixed with acetylene black, a conductive material, and then N-methyl-2-pyrrolidone (NMP), which is polyvinylidene fluoride dissolved in it, was uniformly dispersed in the mixture to create a paste with a mass ratio of carbon:acetylene black:PVDF = 88:5:7. This paste was applied to a Cu foil, dried, rolled to a predetermined thickness, and then 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 (1M-LiPF6 EC / DEC(1 / 1)) prepared by mixing ethylene carbonate and diethyl carbonate in a 1:1 volume ratio and adding 1 mol / L of lithium hexafluorophosphate.

[0107] The electrode group, wound with a separator in between the positive and negative electrode plates, was flattened to fit into the body of the battery cell case. The positive electrode plate was welded to an Al lead, and the negative electrode plate to a Ni lead. The Al lead was welded to the positive terminal on the cover, and the Ni lead was welded to the negative terminal on the cover.

[0108] The lid and body were joined by laser welding or crimping. For laser welding, filler wire of the filler steel type shown in Table 2 was used. The filler was supplied at half the welding speed.

[0109] The inside of the battery was dried in an atmosphere with a dew point of -76°C to remove moisture. The electrolyte was then injected through the injection port in the same atmosphere. The battery was then charged to 3.6-4.2V in the same atmosphere. This procedure electrolyzed any remaining moisture inside the battery. After that, the injection port was closed with a stopper.

[0110] In the example where the lid and body were joined by laser welding, the following conditions were adjusted to obtain a penetration depth approximately equal to the plate thickness of the lid. Continuous wave Output: 0.8~6.0kW Speed: 2.0~20.0m / min Focus shift: 0-10mm (Gathering diameter when using JF: 0.4mm) Shielding gas: Ar

[0111] In the example where the lid and body were joined by seam crimping, the seam crimping was performed using a double seam crimping method.

[0112] The dilution ratios for the Ni-plated steel sheet and filler wire are shown in Tables 3 and 4.

[0113] [Table 3A]

[0114] [Table 3B]

[0115] [Table 4A]

[0116] [Table 4B]

[0117] The following evaluations were performed on each of the obtained battery cases. The results are shown in Tables 3 and 4.

[0118] (Composition of weld metal) The average Cr content and average Ni content of the weld metal were measured using the following method. From the battery cell case, weld metal used to join the lid and the body, and weld metal used to form the body, were cut out, and samples of each weld metal were taken. Using an emission spectrometer (Shimadzu Corporation: ICPS-8100), the components of these samples were measured at five points, and the arithmetic mean was taken as the average Cr content or average Ni content.

[0119] When the average Cr content of the weld metal is [Cr] and the average Ni content is [Ni], [Cr] + 4 × [Ni] ... Equation 1 This value was used as the corrosion resistance index for the weld metal.

[0120] (Leaching test) After sealing the injection port, the battery cell case was held at 80°C for 750 hours. After holding, a portion of the battery case was disassembled in an atmosphere with a dew point of -76°C, and the electrolyte was collected using a pipette or similar tool. The amount of metal leached from the electrolyte was analyzed using an ICP-MS (model: Agilent 7700x, manufactured by Agilent Technologies, Inc.). A score of ○ (Good) was given if the Fe component in the solution was 75 ppm or less, and × (Bad) if it was greater than 75 ppm.

[0121] As can be seen from the results in Tables 3A, 3B, 4A, and 4B, in the examples that met the requirements of the present application, the amount of Fe component dissolved in the solution was trace, less than 75 ppm, and the electrolyte resistance was good.

[0122] Furthermore, the battery case body was created by deep drawing each of the Ni-plated steel sheets shown in Table 1. The molded shape of the body was 148 mm (depth) x 26.5 mm (width) x 91 mm (height).

[0123] Each Ni-plated steel sheet shown in Table 1 was processed into a predetermined shape to create the lid of the battery case. Then, using the above lids and bodies, each battery case was created using the combinations of lids, bodies, and filler steel types shown in Table 5. A battery was placed inside the battery case to create a battery cell case. The method of manufacturing the battery is as described above.

[0124] The lid and body were joined using laser welding. During laser welding, filler wires of the filler steel types shown in Table 2 were used. The following conditions were adjusted to achieve a penetration depth approximately equal to the thickness of the lid plate. Continuous wave Output: 0.8~6.0kW Speed: 2.0~20.0m / min Focus shift: 0-10mm (Gathering diameter when using JF: 0.4mm) Shielding gas: Ar The dilution ratios for the Ni-plated steel sheet and filler wire were as shown in Table 5. The filler was supplied at half the welding speed. Subsequent electrolyte injection and other procedures were carried out as described above.

[0125] For each battery case obtained, the weld metal composition and elution test were evaluated under the conditions described above. The results are shown in Table 5.

[0126] [Table 5]

[0127] As can be seen from the results in Table 5, in the examples that met the requirements of this application, the amount of Fe component dissolved in the solution was trace, less than 75 ppm, and the electrolyte resistance was good. In the example of Experiment No. 112, deep drawing could not be performed due to problems with the formability of the base steel sheet. [Industrial applicability]

[0128] The battery case and battery according to the present invention have high electrolyte resistance. Furthermore, the method for manufacturing the battery case according to the present invention can provide a battery case with high electrolyte resistance. Therefore, the present invention is extremely useful in industry. [Explanation of symbols]

[0129] 1, 2 Battery case 11, 21 Lid 12, 22 Torso 12a, 12b, 12c, 12d, 22a, 22b, 22c, 22d side 12e bottom 30, 31, 32 Weld metal

Claims

1. A battery case comprising a lid, a body, and at least one weld metal, The lid and the body each include a Ni-plated steel material having a base steel material and a Ni-based plating layer. When the average Cr content of the weld metal is [Cr] and the average Ni content of the weld metal is [Ni], the following conditions are met: [Cr] + 4 × [Ni] ≥ 5.

00. A battery case characterized by the following features.

2. The fuselage does not have any welded parts containing the weld metal. The lid and the body are joined together via the weld metal. The battery case according to feature 1.

3. The carbon content of the base steel material of the fuselage is greater than 0% by mass and less than or equal to 0.070% by mass. The battery case according to feature 2.

4. The fuselage has a welded section containing the weld metal, The lid and the body are joined together via the weld metal. The battery case according to feature 1.

5. The fuselage has a welded section containing the weld metal, The lid and the body are joined together by a crimping mechanism. The battery case according to feature 1.

6. The length of the body in the direction perpendicular to the lid is 1.5 times or more the length of the lid in the longitudinal direction. The battery case according to feature 1.

7. The thickness of the Ni-plated steel material is 0.1 to 1.4 mm. A battery case according to any one of claims 1 to 6.

8. The thickness of the Ni-based plating layer is 0.1 to 10.0 μm. A battery case according to any one of claims 1 to 6.

9. The basis weight of the Ni-based plating layer is 2.0 to 89.0 g / m². ２ That is, A battery case according to any one of claims 1 to 6.

10. A Fe-Ni alloy layer is provided between the Ni-based plating layer and the base steel material. A battery case according to any one of claims 1 to 6.

11. The excess height of the weld metal is 50% or less of the plate thickness of the Ni-plated steel material. A battery case according to any one of claims 1 to 6.

12. It is a neutral can. A battery case according to any one of claims 1 to 6.

13. A battery comprising the battery case according to any one of claims 1 to 6.

14. A method for manufacturing a battery case comprising a lid, a body, and at least one weld metal, A lid forming step involves processing a plated steel material having a base steel material and a Ni-based plating layer to form the lid, A fuselage forming step involves processing a plated steel material having a base steel material and a Ni-based plating layer to form the fuselage, A joining step of joining the lid and the body, Includes, When the average Cr content of the weld metal is [Cr] and the average Ni content of the weld metal is [Ni], the following conditions are met: [Cr] + 4 × [Ni] ≥ 5.

00. A method for manufacturing a battery case, characterized by the following features.

15. In the fuselage formation process, the fuselage is formed by deep drawing. In the joining process, the lid and the body are joined by welding. The method for manufacturing a battery case according to claim 14.

16. In the fuselage formation step, the fuselage is formed by welding. In the joining process, the lid and the body are joined by welding. The method for manufacturing a battery case according to claim 14.

17. In the fuselage formation step, the fuselage is formed by welding. In the joining process, the lid and the body are joined by crimping. The method for manufacturing a battery case according to claim 14.

18. The weld metal is formed using an austenitic filler wire. A method for manufacturing a battery case according to any one of claims 14 to 17.

19. The weld metal is formed using a filler wire. The feed rate of the filler wire is 0.1 to 3.0 times the welding rate. A method for manufacturing a battery case according to any one of claims 14 to 17.

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