Surface-treated steel sheet, manufacturing method for surface-treated steel sheet, and manufacturing method for battery components

Abstract

A surface-treated steel sheet according to one embodiment of the present invention comprises a base steel sheet, a Ni-containing layer disposed on the surface of the base steel sheet, and a Ni-W alloy layer disposed on the surface of the Ni-containing layer, the Ni-containing layer having an Fe diffusion alloy layer, and the Ni-W alloy layer being porous. A method for producing a surface-treated steel sheet according to another embodiment of the present invention comprises a step of electrolytically plating a base steel sheet with Ni, a step of pickling the base steel sheet with the Ni-plated layer, a step of electrolytically plating the base steel sheet with the Ni-plated layer with Ni-W alloy, and a step of annealing the base steel sheet with the Ni-plated layer and the Ni-W alloy layer disposed thereon, wherein the pickling bath is a 70-100 g / L sulfuric acid bath, the time for immersing the base steel sheet with the Ni-plated layer in the bath during the pickling is 25-35 seconds, the annealing temperature during the annealing is 630-860° C., and the annealing time during the annealing is 10-180 s.

Description

[Technical field]

[0001] The present invention relates to a surface-treated steel sheet, a method for manufacturing a surface-treated steel sheet, and a method for manufacturing a battery component. [Background technology]

[0002] Ni-plated steel sheets have been used as surface-treated steel sheets for battery cans. Due to the excellent chemical stability of Ni, Ni-plated steel sheets are used for various battery containers, such as battery cans for alkaline manganese dry batteries, lithium ion batteries, and nickel-metal hydride batteries.

[0003] In recent years, Ni-W alloy plated steel sheets containing an alloy of Ni and W as the main components have also begun to be used as materials for battery cans, etc. Examples of Ni-W alloy plated steel sheets are the steel sheets described in Patent Documents 1-4.

[0004] Patent Document 1 discloses a plated steel sheet for battery containers, characterized in that an iron-nickel alloy layer, a nickel layer, and a nickel-tungsten alloy layer are formed, in that order from the bottom, on the side of the steel sheet that will become the inner surface of the battery container.

[0005] Patent Document 2 discloses a Ni-containing surface-treated steel sheet for containers formed by press molding, which includes a steel sheet having a first surface that will become the outside of the container after the press molding, a Ni-containing layer disposed on the first surface of the steel sheet, and a Ni-W alloy plating layer disposed on the Ni-containing layer. The Ni-containing layer has an Fe-Ni diffusion alloy layer, and the amount of Ni contained in the Ni-containing layer is 5 g / m 2 More than 89g / m 2 the thickness of the Ni-W alloy plating layer is 0.02 μm or more and 2 μm or less; and the W concentration in the Ni-W alloy plating layer is, in mass %, 10% or more and 65% or less.

[0006] Patent Document 3 discloses a steel sheet for a non-aqueous electrolyte secondary battery case, comprising: a steel sheet; and a Ni-W-Fe alloy plating layer formed on the surface of the steel sheet, containing a Ni-W-Fe alloy, and serving as the inner surface of the non-aqueous electrolyte secondary battery case.

[0007] Patent Document 4 discloses a steel sheet for use in battery cans of inside-out type alkaline batteries, characterized in that the steel sheet has a plating layer selected from nickel-tungsten (Ni-W) and nickel-cobalt-tungsten (Ni-Co-W) alloys on the surface of one main surface of a base material made of a plate-shaped steel material, and the plating layer has irregularities on the surface formed by dissolution of the tungsten. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2007-51325 A [Patent Document 2] International Publication No. 2012 / 137823 [Patent Document 3] International Publication No. 2017 / 006834 [Patent Document 4] JP 2020-155202 A Summary of the Invention [Problem to be solved by the invention]

[0009] A tab is resistance welded to the battery can. The tab is usually a thin plate made of a material with low electrical resistance, such as nickel or copper. Because the tab has a low electrical resistance and is thin, it is very difficult to resistance weld the tab to the battery can. This is because resistance heating is unlikely to occur in the tab during resistance welding.

[0010] Increasing the welding current value can increase the amount of resistance heat generated. However, resistance welding using a large current can cause holes in the thin tabs, making them unusable. Therefore, there is a strong demand for a surface-treated steel sheet for battery cans that can reduce the appropriate current range when resistance welding the tabs.

[0011] The appropriate current range is the range of welding current values ​​that allows resistance welding without causing welding defects. Normally, a welding current below the lower limit of the appropriate current range cannot melt the surface-treated steel sheet and the tab, which are the welding base material, and cannot form a nugget that joins the two. Also, a welding current above the upper limit of the appropriate current range causes damage to the welding base material.

[0012] In Patent Document 1, suppression of contact resistance and improvement of discharge characteristics are taken as issues to be addressed, but no particular consideration is given to the weldability between the plated steel sheet and the tab.

[0013] In Patent Document 2, improving corrosion resistance after press forming is taken as an issue, but no particular consideration is given to the weldability between the plated steel sheet and the tab.

[0014] Patent Document 3 addresses the issue of suppressing deterioration of battery performance and corrosion of the case due to metal elution when the potential of the battery case increases, but does not specifically address the weldability of the plated steel sheet and the tab.

[0015] In Patent Document 4, the improvement of the high-load discharge performance and long-term storage performance of the steel sheet is taken as an issue, but no particular consideration is given to the weldability between the plated steel sheet and the tab.

[0016] In view of the above circumstances, an object of the present invention is to provide a surface-treated steel sheet that can reduce the appropriate current range when resistance welding battery tabs without impairing workability, and a manufacturing method thereof. [Means for solving the problem]

[0017] The gist of the present invention is as follows.

[0018] (1) A surface-treated steel sheet according to one embodiment of the present invention comprises a base steel sheet, a Ni-containing layer disposed on a surface of the base steel sheet, and a Ni-W alloy layer disposed on the surface of the Ni-containing layer, wherein the Ni-containing layer has an Fe-diffused alloy layer, and the Ni-W alloy layer is porous. (2) In the surface-treated steel sheet according to the above (1), the Ni—W alloy layer preferably has an average W concentration of 10 to 45 mass %. (3) Preferably, in the surface-treated steel sheet according to the above (1) or (2), the Ni--W alloy layer has a thickness of 0.01 to 2.0 μm. (4) In the surface-treated steel sheet according to any one of the above (1) to (3), preferably, the Ni coating weight contained in the Ni-containing layer and the Ni-W alloy layer is 1.8 to 35.6 g / m 2 It is. (5) Preferably, in the surface-treated steel sheet according to any one of the above (1) to (4), the Fe-diffused alloy layer has a thickness of 0.1 to 3.0 μm. (6) Preferably, in the surface-treated steel sheet according to any one of the above (1) to (5), only a part of the Ni-containing layer is the Fe-diffused alloy layer. (7) In the surface-treated steel sheet according to any one of the above (1) to (6), preferably, the entire Ni-containing layer is the Fe-diffusion alloy layer, and a portion of the Ni-W alloy layer is the Fe-diffusion alloy layer.

[0019] (8) A method for producing a surface-treated steel sheet according to another embodiment of the present invention includes the steps of electrolytically Ni-plating a base steel sheet, pickling the base steel sheet having a Ni-plated layer, electrolytically Ni-W alloy plating the base steel sheet having the Ni-plated layer, and annealing the base steel sheet having the Ni-plated layer and a Ni-W alloy layer disposed thereon, wherein a pickling bath in the pickling step is a 70-100 g / L sulfuric acid bath, a time for immersing the base steel sheet having the Ni-plated layer in the bath in the pickling step is 25-35 seconds, an annealing temperature in the annealing step is 630-860°C, and an annealing time in the annealing step is 10-180 s.

[0020] (9) A method for producing a battery component according to another aspect of the present invention includes a step of resistance welding a tab to the surface-treated steel sheet according to (1) or (2) above. (10) In the method for producing a battery component described above in (9), preferably, a welding voltage in the resistance welding is set to 2.0 V to 3.5 V, and a current application time in the resistance welding is set to 1.0 ms to 10.0 ms. Effect of the Invention

[0021] According to the present invention, it is possible to provide a surface-treated steel sheet and a manufacturing method thereof that are capable of reducing the appropriate current range when resistance welding battery tabs without impairing workability. [Brief description of the drawings]

[0022] [Figure 1] 1 is a schematic cross-sectional view of an example of a surface-treated steel sheet according to an embodiment of the present invention, and an enlarged view of a Ni—W alloy layer. [Diagram 2] FIG. 2 is a schematic cross-sectional view of another example of the surface-treated steel sheet according to the present embodiment. [Figure 3A] 1 is a TEM observation photograph of an example of a Ni—W alloy layer of a surface-treated steel sheet according to an embodiment of the present invention. [Figure 3B] 1 is a TEM observation photograph of an example of a Ni—W alloy layer of a surface-treated steel sheet according to an embodiment of the present invention. [Figure 3C] 1 is a TEM observation photograph of an example of a Ni—W alloy layer of a surface-treated steel sheet according to an embodiment of the present invention. [Figure 4] 2 is a flowchart illustrating an example of a method for manufacturing a surface-treated steel sheet according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] (1. Surface-treated steel sheet 1) As shown in Fig. 1 etc., a surface-treated steel sheet 1 according to one embodiment of the present invention comprises a base steel sheet 11, a Ni-containing layer 12 disposed on the surface of the base steel sheet 11, and a Ni-W alloy layer 13 disposed on the surface of the Ni-containing layer 12, the Ni-containing layer 12 having an Fe-diffused alloy layer 14, and the Ni-W alloy layer 13 being porous. Hereinafter, the surface-treated steel sheet 1 according to this embodiment will be described in detail. Note that the entire plating layer including the Ni-containing layer 12 and the Ni-W alloy layer 13 may be simply referred to as the "plating layer".

[0024] (Base material steel plate 11) The surface-treated steel sheet 1 has a base steel sheet 11. The base steel sheet 11 is a steel sheet that serves as a substrate for the surface-treated steel sheet 1. The components, sheet thickness, metal structure, and the like of the base steel sheet 11 are not particularly limited and can be appropriately selected depending on the application of the surface-treated steel sheet 1.

[0025] (Ni-containing layer 12) The surface-treated steel sheet 1 has a Ni-containing layer 12 disposed on the surface of a base steel sheet 11. The Ni-containing layer 12 is a layer containing Ni that is provided on the surface of the base steel sheet 11. The Ni-containing layer 12 may be provided on only one surface of the base steel sheet 11, or on both surfaces.

[0026] (Ni-W alloy layer 13) The surface-treated steel sheet 1 further has a Ni-W alloy layer 13 disposed on the surface of the Ni-containing layer 12. The Ni-W alloy layer 13 is an alloy plating layer containing Ni as a main component and further containing W. The Ni-W alloy plating is harder than Ni. By analyzing the component distribution of the plating layer using glow discharge optical emission spectrometry, which is an analytical method capable of measuring the distribution of chemical components in the depth direction from the surface of the plating layer, it is possible to distinguish between the Ni-W alloy layer 13 having a high W concentration and the Ni-containing layer 12 having a low W concentration.

[0027] The Ni-W alloy layer 13 may be provided on only one surface or both surfaces of the base steel sheet 11. A surface treatment layer such as a coating film may be further provided on the surface of the Ni-W alloy layer 13.

[0028] (Fe diffusion alloy layer 14) At least a portion of the Ni-containing layer 12 is an Fe-diffusion alloy layer 14. That is, the Ni-containing layer 12 has an Fe-diffusion alloy layer 14. The Fe-diffusion alloy layer 14 is an alloy layer formed by diffusing Fe of the base steel sheet 11 into the inside of the plating layer. The Fe-diffusion alloy layer 14 is obtained, for example, by plating the surface of the base steel sheet 11 and then performing an alloying treatment such as annealing.

[0029] In the cross-sectional schematic diagram illustrated in FIG. 1, only a part of the Ni-containing layer 12 is the Fe diffusion alloy layer 14 in contact with the base steel plate 11. On the other hand, as illustrated in FIG. 2, the entire Ni-containing layer 12 may be the Fe diffusion alloy layer 14. Also, as illustrated in FIG. 2, the Fe diffusion alloy layer 14 may extend to the Ni-W alloy layer 13. That is, the Ni-W alloy layer 13 may have the Fe diffusion alloy layer 14. Only a part of the Ni-W alloy layer 13 may be the Fe diffusion alloy layer 14, or the entire Ni-W alloy layer 13 may be the Fe diffusion alloy layer 14. The Fe diffusion alloy layer 14 formed in the Ni-containing layer 12 may be referred to as a Ni-Fe alloy layer, and the Fe diffusion alloy layer 14 formed in the Ni-W alloy layer 13 may be referred to as a Ni-W-Fe alloy layer. In general, a surface-treated steel sheet in which only a portion of the Ni-containing layer 12 is the Fe diffusion alloy layer 14 and a surface-treated steel sheet in which the entire Ni-containing layer 12 is the Fe diffusion alloy layer 14 and only a portion of the Ni-W alloy layer 13 is the Fe diffusion alloy layer 14 are referred to as a partial diffusion-plated steel sheet. Also, a surface-treated steel sheet in which the entire Ni-containing layer 12 and the entire Ni-W alloy layer 13 are the Fe diffusion alloy layer 14 are referred to as a fully diffusion-plated steel sheet.

[0030] (Porous structure of Ni-W alloy layer 13) The Ni-W alloy layer 13 of the surface-treated steel sheet 1 according to this embodiment is porous. That is, as shown in the schematic diagram of FIG. 1 and the enlarged photographs of FIG. 3A to FIG. 3C, the Ni-W alloy layer 13 has a large number of voids B. The voids B are very small, with a diameter of about 5 nm to 10 nm. The presence of the voids B can be identified by observing the cross section of the Ni-W alloy layer 13 with a high-resolution TEM. The voids B contained in the Ni-W alloy layer 13 are a different concept from pinholes. A pinhole is a fine and long hole that penetrates from the surface of the plating layer to the base steel sheet. On the other hand, the voids B in the Ni-W alloy layer 13 of the surface-treated steel sheet 1 according to this embodiment are granular.

[0031] An example of a cross-sectional photograph of the Ni-W alloy layer 13 is shown in FIG. 3A to FIG. 3C. The photographs in FIG. 3A to FIG. 3C are a BF (bright-field) image, a HAADF (high-angle annular dark field) image, and element mapping images of Fe, Ni, O, and W of the same region. The white area present from the center to the top of the HAADF image is the Ni-W alloy layer 13. The gray area present at the bottom of the HAADF image is the Ni-containing layer 12. The HAADF image of the Ni-W alloy layer 13 contains many small dark dots. These dots are voids B. In the HAADF image, areas with low mass density in the direction perpendicular to the paper are shown dark. The dark dots in the HAADF image in FIG. 3B have a lower mass density than their surroundings. Since light elements are not intentionally added to the Ni-W alloy layer 13, it is not considered that light elements are segregated in the dark areas. Therefore, it is considered that the dark dots in the HAADF image in FIG. 3B are voids B.

[0032] In the HAADF image of FIG. 3B, one of the many voids B is surrounded by a dashed line. As shown in the HAADF image of FIG. 3B, in the surface-treated steel sheet 1 according to this embodiment, many voids B are formed throughout the entire cross section of the Ni-W alloy layer 13. On the other hand, when no voids B are formed, the TEM photograph of the Ni-W alloy layer 13 has a flat color tone. Therefore, by performing high-resolution TEM observation, it is easy to determine whether the Ni-W alloy layer 13 is porous or not.

[0033] (Action and effect) The surface-treated steel sheet 1 according to this embodiment has a Ni-W alloy layer 13. W has the function of increasing the electrical resistance of the plating layer. Therefore, the Ni-W alloy layer 13 increases the surface resistance of the surface-treated steel sheet 1 and improves weldability.

[0034] However, W hardens the Ni plating layer, impairing its workability. A plating layer with poor workability is prone to cracks during press forming and other processes. A crack is a break that extends from the surface of the plating layer to the base material. Cracks expose the base material to the outside of the plating, accelerating corrosion of the base material. Ni plating and Ni-W alloy plating do not have a sacrificial corrosion protection effect, so Ni-plated steel sheets and Ni-W alloy-plated steel sheets are prone to corrosion starting from cracks in the plating.

[0035] In order to improve the workability of the plating layer, the present inventors provided a Ni-containing layer 12 between the Ni-W alloy layer 13 and the base steel sheet 11. Furthermore, at least a part of the Ni-containing layer 12 was alloyed. The Ni-containing layer 12 and the Fe-diffused alloy layer 14 prevent cracks from progressing to the base steel sheet 11, and thus prevent the base steel sheet 11 from being exposed to a corrosive environment.

[0036] However, the present inventors considered that it would be more preferable to improve the workability of the Ni-W alloy layer 13 itself. Therefore, they investigated a method for increasing the electrical resistance of the Ni-W alloy layer 13 while suppressing the W content of the Ni-W alloy layer 13. Then, the present inventors found that it is possible to increase the electrical resistance of the Ni-W alloy layer 13 while suppressing the W content by making the Ni-W alloy layer 13 porous. The present inventors presume that the voids B have the effect of narrowing the cross-sectional area of ​​the current path and increasing the current density, thereby increasing the surface resistance of the surface-treated steel sheet 1. Therefore, when comparing the electrical resistance of the porous Ni-W alloy layer 13 and a normal Ni-W alloy layer having the same W content, the electrical resistance of the porous Ni-W alloy layer 13 is higher than that of the normal Ni-W alloy layer.

[0037] There is no particular limitation on the means for making the Ni-W alloy layer 13 porous. According to the findings of the present inventors, for example, the Ni plating layer is subjected to an appropriate pickling treatment before the formation of the Ni-W alloy layer 13, and the Ni-W alloy layer 13 is subjected to an alloying treatment under specific conditions, thereby making the Ni-W alloy layer 13 porous.

[0038] As described above, in the surface-treated steel sheet 1 according to this embodiment, the porous Ni-W alloy layer 13 is used to improve the surface resistance. Note that W contained in the Ni-W alloy layer 13 reduces the workability of the surface-treated steel sheet, but the Ni-containing layer 12 and the Fe-diffusion alloy layer 14 compensate for this. Furthermore, in the surface-treated steel sheet 1 according to this embodiment, since the Ni-W alloy layer 13 is porous, the W content of the Ni-W alloy layer 13 can be suppressed to a low value while maintaining a high surface resistance value. As a result, the surface-treated steel sheet 1 according to this embodiment can reduce the appropriate current range when resistance welding a battery tab without impairing the workability.

[0039] The above describes the most basic aspect of the surface-treated steel sheet 1 according to this embodiment. Next, a more preferred aspect of the surface-treated steel sheet 1 according to this embodiment will be described.

[0040] (Average W concentration in Ni-W alloy layer 13) The Ni-W alloy layer 13 contains Ni as a main component and further contains W. "The main component of the Ni-W alloy layer 13 is Ni" means that Ni is the component with the highest mass concentration in the Ni-W alloy layer 13. The average W concentration in the Ni-W alloy layer 13 is not particularly limited, but may be within the range of 10 to 45 mass %, for example.

[0041] W increases the electrical resistance of the Ni-W alloy layer 13. The inventors presume that W has the function of making the Ni-W alloy layer 13 porous under specific annealing conditions. By setting the average W concentration within the above-mentioned range, the electrical resistance of the Ni-W alloy layer 13 can be further increased. The average W concentration in the Ni-W alloy layer 13 may be 15 mass% or more, 20 mass% or more, 25 mass% or more, or 30 mass% or more. In addition, by reducing the W concentration in the Ni-W alloy layer 13, the workability of the Ni-W alloy layer 13 can be further improved. Therefore, the average W concentration in the Ni-W alloy layer 13 may be 45 mass% or less, 42 mass% or less, 40 mass% or less, or 38 mass% or less. For example, the Ni-W alloy layer 13 may contain Cr, Mo, etc.

[0042] (Thickness of Ni-W alloy layer 13) The thickness of the Ni-W alloy layer 13 is not particularly limited. Even if the thickness is small, the Ni-W alloy layer 13 increases the surface resistance value of the surface-treated steel sheet 1. In addition, from the viewpoint of further increasing the workability of the Ni-W alloy layer 13, it is advantageous for the Ni-W alloy layer 13 to have a small thickness. On the other hand, from the viewpoint of further increasing the surface resistance value of the Ni-W alloy layer 13, it is advantageous for the Ni-W alloy layer 13 to have a large thickness. Therefore, the thickness of the Ni-W alloy layer 13 may be, for example, 0.01 μm or more. This can further increase the surface resistance of the surface-treated steel sheet 1. The thickness of the Ni-W alloy layer 13 may be 0.05 μm or more, 0.08 μm or more, or 0.10 μm or more. The upper limit of the thickness of the Ni-W alloy layer 13 is not particularly specified. For example, the Ni-W alloy layer 13 may be 2.0 μm or less, 1.5 μm or less, or 1.0 μm or less.

[0043] (Thickness of Ni-containing layer 12) The thickness of the Ni-containing layer 12 is not particularly limited. Even if the Ni-containing layer 12 is only slightly thick, it has the effect of suppressing the progress of cracks. On the other hand, from the viewpoint of further improving the workability of the surface-treated steel sheet 1, it is advantageous for the Ni-containing layer 12 to be thicker. Therefore, the thickness of the Ni-containing layer 12 may be, for example, 0.2 μm or more. This further improves the workability of the surface-treated steel sheet 1. The thickness of the Ni-containing layer 12 may be 0.7 μm or more, 1.0 μm or more, or 1.5 μm or more. The upper limit of the thickness of the Ni-containing layer 12 is not particularly specified. For example, the Ni-containing layer 12 may be 4.0 μm or less, 3.0 μm or less, or 2.0 μm or less.

[0044] (Ni deposition amount) The amount of Ni contained in the plating layer (i.e., the Ni-containing layer 12 and the Ni-W alloy layer 13) is not particularly limited, but is, for example, 1.8 to 35.6 g / m 2 The Ni coating weight may be within the range of 1.8 g / m 2 Setting the Ni coating weight to 35.6 g / m or more further improves the corrosion resistance of the surface-treated steel sheet 1. 2 By setting the Ni coating amount to 4.5 g / m or less, the manufacturing cost of the surface-treated steel sheet 1 can be reduced. 2 More than 6.2g / m 2 or more than 8.9 g / m 2 The Ni coating weight may be 26.7 g / m or more. 2 Below, 17.8g / m 2 or less than 13.4 g / m 2 It may be the following.

[0045] The thickness of the plating layer (that is, the total thickness of the Ni-containing layer 12 and the Ni-W alloy layer 13) is not particularly limited. For example, the thickness of the plating layer may be within a range of 0.2 μm to 4.0 μm.

[0046] (Thickness of Fe-diffused alloy layer 14) The thickness of the Fe diffusion alloy layer 14 is not particularly limited. Even if the thickness is small, the Fe diffusion alloy layer 14 can suppress the progress of cracks, improve the workability of the surface-treated steel sheet 1, and improve the corrosion resistance of the processed part. On the other hand, the thickness of the Fe diffusion alloy layer 14 may be, for example, 0.1 μm or more. This can further improve the workability of the surface-treated steel sheet 1. The thickness of the Fe diffusion alloy layer 14 may be 0.2 μm or more, 0.5 μm or more, or 1.0 μm or more. The upper limit of the thickness of the Fe diffusion alloy layer 14 is not particularly specified. For example, the entire plating layer may be the Fe diffusion alloy layer 14. On the other hand, the Fe diffusion alloy layer 14 may be 3.0 μm or less, 2.5 μm or less, or 2.0 μm or less.

[0047] (Components of Ni-containing layer 12) The Ni-containing layer 12 is a layer mainly composed of Ni and Fe diffused from the base steel sheet 11. For example, the total content of Ni and Fe in the Ni-containing layer 12 may be 98.0 mass% or more, 98.5 mass% or more, or 99.0 mass% or more. The total content of Ni and Fe in the Ni-containing layer 12 may be 100 mass% or less, 99.5 mass% or less, or 99.0 mass% or less. The ratio of Ni and Fe in the Ni-containing layer 12 is not uniform in the thickness direction of the Ni-containing layer 12 (thickness direction of the surface-treated steel sheet). This is because, as described above, a part or the whole of the Ni-containing layer 12 is made into the Fe diffusion alloy layer 14, and the amount of Fe diffused from the base steel sheet 11 in the Fe diffusion alloy layer 14 differs in the thickness direction of the Fe diffusion alloy layer 14. In the Fe diffusion alloy layer 14, the Fe content increases closer to the base steel sheet 11. The thickness of the Fe diffusion alloy layer 14 can be appropriately selected.

[0048] The Ni-containing layer 12 may contain elements other than Ni and Fe. For example, the Ni-containing layer 12 may contain Cr and Mo. For example, the Ni-containing layer 12 may contain one or more of Cr and Mo, and the total content thereof may be more than 0 mass% and 0.1 mass% or less. In addition, various alloy elements contained in the base steel plate 11 may diffuse into the Ni-containing layer 12 during the alloying treatment. Therefore, the Ni-containing layer 12 may contain various impurity elements. In addition, W may diffuse into the Ni-containing layer 12 from the Ni-W alloy layer 13. However, the W content of the Ni-containing layer 12 is usually less than 1.0%.

[0049] (Components of Ni-W alloy layer 13) As described above, the Ni-W alloy layer 13 contains Ni as a main component and further contains W. As illustrated in FIG. 2, when a part or all of the Ni-W alloy layer 13 is the Fe diffusion alloy layer 14, the Ni-W alloy layer 13 may further contain Fe. When the Ni-W alloy layer 13 does not have the Fe diffusion alloy layer 14, the total content of Ni and W in the Ni-W alloy layer 13 may be 95.0 mass% or more, 96.0 mass% or more, or 97.0 mass% or more. When the Ni-W alloy layer 13 does not have the Fe diffusion alloy layer 14, the total content of Ni and W in the Ni-W alloy layer 13 may be 100 mass% or less, 99.0 mass% or less, or 98.0 mass% or less. When the Ni-W alloy layer 13 has the Fe diffusion alloy layer 14, the total content of Ni, W, and Fe in the Ni-W alloy layer 13 may be 95.0 mass% or more, 96.0 mass% or more, or 97.0 mass% or more. When the Ni--W alloy layer 13 has the Fe-diffused alloy layer 14, the total content of Ni, W, and Fe in the Ni--W alloy layer 13 may be 100 mass % or less, 99.0 mass % or less, or 98.0 mass % or less.

[0050] Like the Ni-containing layer 12, the Ni-W alloy layer 13 may contain elements other than Ni, W, and Fe. For example, the Ni-W alloy layer 13 may contain Cr and Mo. For example, the Ni-W alloy layer 13 may contain one or more of Cr, Co, and Mo, and the total content thereof may be more than 0 mass% and 5 mass% or less. The Ni-W alloy layer 13 may also contain various impurity elements.

[0051] (11 types of base steel plate, etc.) The components and metal structure of the base steel sheet 11 are not particularly limited. The components and metal structure of the base steel sheet 11 can be appropriately selected depending on the application of the surface-treated steel sheet 1. For example, the chemical components of the base steel sheet 11 may contain, in unit mass%, C: 0.0001 to 0.08, Si: 0.001 to 0.03, Mn: 0.01 to 0.4, P: 0.001 to 0.03, S: 0.000 to 0.03, and the balance may contain iron and impurities. The base steel sheet 11 may contain elements other than C, Si, Mn, P, and S.

[0052] When the surface-treated steel sheet 1 is used as a material for a battery container, for example, the base steel sheet 11 is preferably low carbon aluminum-killed steel, IF steel (Interstitial Free Steel / ultra-low carbon steel), etc. Specific examples of the chemical composition (unit: mass%) of the base steel sheet 11 are as follows: (Example 1) Low carbon aluminum killed steel C: 0.057, Si: 0.004, Mn: 0.29, P: 0.014, S: 0.007, Al: 0.050, Cu: 0.034, Ni: 0.021, balance: Fe and impurities (Example 2) IF steel C: 0.004, Si: 0.01, Mn: 0.16, P: 0.013, S: 0.006, Al: 0.029, Cu: 0.027, Ni: 0.022, Ti: 0.013, balance: iron and impurities (Example 3) IF steel C: 0.0012, Si: less than 0.01, Mn: 0.16, P: 0.013, S: 0.006, Al: 0.029, Cu: 0.027, Ni: 0.022, Ti: 0.020, balance: iron and impurities

[0053] There is also no particular limitation on the thickness of the base steel sheet 11. When the surface-treated steel sheet 1 is used, for example, as a material for a battery container, the thickness of the base steel sheet 11 is preferably, for example, 0.15 to 2.00 mm.

[0054] (Measurement method) The determination of whether the Ni-W alloy layer 13 is porous or not is performed by the following procedure. First, the surface-treated steel sheet 1 is processed into a foil piece using a FIB (Focused Ion Beam) so that the cross section can be observed along the plate thickness direction. The sample obtained in this way is analyzed using a FE-SEM (Field-Emission Scanning Electron Microscopy) with a STEM (Scanning Transmission Electron Microscope) mode capable of elemental analysis by EDS. The type of the device is Titan (Thermo Fischer Scientific). The acceleration voltage was 300 kV. The measurement magnification was 140,000 times. When looking at the HAADF image, the smaller the mass in the transmission direction, the darker the image becomes, so the black parts are considered to be elements lighter than Ni and W, or voids, but the presence of elements lighter than Ni is unlikely, and they can be determined to be voids. When a large number of voids are formed throughout the entire cross section of the Ni-W alloy layer 13, the Ni-W alloy layer 13 is determined to be porous. Specifically, five arbitrary 100 nm × 100 nm regions are observed from the Ni-W alloy layer 13 in the obtained HAADF image, and the number of voids with a diameter of 5 nm or more is counted. The numbers of voids with a diameter of 5 nm or more identified in the five 100 nm × 100 nm regions are added together and divided by 5 to obtain the average number of voids with a diameter of 5 nm or more per region. If the average number of voids with a diameter of 5 nm or more per region in the five regions is 5 or more, the Ni-W alloy layer 13 is determined to be porous.

[0055] The method for measuring the average W concentration in the Ni-W alloy layer 13 is as follows. Measurement is performed using XPS (X-ray Photoelectron Spectroscopy). First, the surface of the surface-treated steel sheet 1 is sputtered using argon and / or xenon. Next, the components of the Ni-W alloy layer 13 of the surface-treated steel sheet 1 are measured from the surface toward the inside. After the measurement is completed, the cycle of sputtering again and then measuring is repeated. The analysis results of the W concentration along the depth direction are plotted on a graph in which the horizontal axis represents the depth from the surface of the Ni-W alloy layer 13 and the vertical axis represents the W concentration. The value obtained by integrating the graph of the W concentration is divided by the width of the interval (i.e., the thickness of the Ni-W alloy layer 13) and is regarded as the average W concentration. The above-mentioned calculation performed on the W concentration is also applied to the Ni and Fe analysis results, so that the average Ni concentration and the average Fe concentration in the Ni-W alloy layer 13 can be obtained. The component measurement of the plating layer using XPS is performed using a Mg radiation source. In the analysis using the Mg radiation source, there were no Auger peaks overlapping with the photoelectron peaks of Ni, W, or Fe. Peaks of 2p orbitals of Fe, 2p orbitals of Ni, and 4f orbitals of W were observed.

[0056] The Ni deposition amount is measured by inductively coupled plasma optical emission spectroscopy (ICP-OES). First, a plated layer of a specified area is dissolved in acid. Next, the total Ni amount contained in the solution is quantitatively analyzed by ICP-OES. The total Ni amount quantified by ICP-OES is divided by the specified area described above to obtain the Ni deposition amount per unit area.

[0057] The thickness of the Ni-containing layer 12, the Ni-W alloy layer 13, and the Fe-diffused alloy layer 14 are measured by GDS (Glow Discharge Optical Emission Spectrometry). By using GDS to measure the distribution of element concentrations in the Ni-containing layer 12 and the Ni-W alloy layer 13 in the depth direction from the plating layer surface, element concentration curves can be obtained.

[0058] The measurement is performed using a high-frequency glow discharge optical emission surface analyzer (manufactured by Horiba, Ltd., model number: GD-Profiler2). The GDS measurement conditions are as follows: Anode diameter: φ4mm Gas: Ar Gas pressure: 600Pa Output: 35W

[0059] In the surface-treated steel sheet 1 according to this embodiment, a region in the plating layer containing an Fe concentration of 5.0 mass % or more is regarded as an Fe-diffused alloy layer 14. When a component analysis is performed continuously from the surface of the plating layer in the depth direction, the Fe concentration increases closer to the base steel sheet 11. A location with an Fe concentration of 5.0 mass %, identified by a component analysis performed continuously from the surface of the plating layer in the depth direction, is regarded as an interface between the Fe-diffused alloy layer 14 and a plating layer that is not the Fe-diffused alloy layer 14.

[0060] Moreover, in the surface-treated steel sheet 1 according to this embodiment, the region where the Ni concentration is 1.0 mass % or more is regarded as the plating layer, and the other region is regarded as the base steel sheet 11. In the plating layer of the surface-treated steel sheet 1 manufactured by alloying treatment, the Ni concentration decreases toward the base steel sheet 11. A location where the Ni concentration is 1.0 mass %, which is identified by continuously performing component analysis from the surface of the plating layer in the depth direction, is regarded as the interface between the plating layer and the base steel sheet 11 (i.e., the interface between the Fe-diffused alloy layer 14 and the base steel sheet 11).

[0061] The distance between these interfaces is regarded as the thickness of the Fe-diffused alloy layer 14 in the sample obtained by the above-mentioned procedure. This measurement is performed on five samples, and the average value is calculated. This average value is regarded as the thickness of the Fe-diffused alloy layer 14 of the surface-treated steel sheet 1.

[0062] Furthermore, in the surface-treated steel sheet 1 according to this embodiment, a region in the plating layer where the W concentration is 1.0 mass% or more is regarded as the Ni-W alloy layer 13, and a region where the W concentration is less than 1.0 mass% is regarded as the Ni-containing layer 12. A location where the W concentration is 1.0 mass%, which is identified by continuously performing a component analysis from the surface of the plating layer in the depth direction, is regarded as the interface between the Ni-W alloy layer 13 and the Ni-containing layer 12.

[0063] The distance from the interface between the Ni-W alloy layer 13 and the Ni-containing layer 12 to the interface between the plating layer and the base steel sheet 11 is regarded as the thickness of the Ni-containing layer 12 in the sample obtained by the above-mentioned procedure. This measurement is performed on five samples, and the average value is calculated. This average value is regarded as the thickness of the Ni-containing layer 12 of the surface-treated steel sheet 1. In addition, the distance from the surface of the plating layer to the interface between the Ni-W alloy layer 13 and the Ni-containing layer 12 is regarded as the thickness of the Ni-W alloy layer 13 in the sample obtained by the above-mentioned procedure. This measurement is performed on five samples, and the average value is calculated. This average value is regarded as the thickness of the Ni-W alloy layer 13 of the surface-treated steel sheet 1.

[0064] (2. Method for producing surface-treated steel sheet 1) Next, a method for producing a surface-treated steel sheet according to the present embodiment will be described. For example, the method for producing a surface-treated steel sheet 1 having the above-mentioned components can be suitably obtained by the method according to the present embodiment.

[0065] As illustrated in FIG. 4, a method for producing a surface-treated steel sheet according to another embodiment of the present invention includes the steps of: (S1) a step of electrolytically plating a base steel sheet 11 with Ni; (S2) A step of pickling the base steel sheet 11 having a Ni plating layer; (S3) a step of performing electric Ni-W alloy plating on the base steel sheet 11 having a Ni plating layer; (S4) annealing the base steel sheet 11 having the Ni plating layer and the Ni-W alloy layer 13 disposed thereon; In the pickling, the pickling bath is a 70 to 100 g / L sulfuric acid bath, the time for immersing the base steel sheet having the Ni plating layer in the bath (immersion time) is 25 to 35 seconds, the annealing temperature in the annealing is 630 to 860°C, and the annealing time in the annealing is 10 to 180 seconds.

[0066] (S1 Electroplating) First, a base steel sheet 11 is electroplated with Ni. The plating base material is the same as the base steel sheet 11 of the surface-treated steel sheet 1 according to the present embodiment described above. As a result, a Ni-containing layer 12 is provided on the surface of the base steel sheet 11, as shown in Fig. 4. The plated steel sheet obtained by electroplating with Ni is hereinafter referred to as a Ni-plated steel sheet.

[0067] (S2 pickling) Next, the Ni-plated steel sheet is pickled under the following pickling conditions: Pickling bath: 70~100g / L sulfuric acid bath Immersion time: 25-35 seconds In addition, it is desirable to rinse the Ni-plated steel sheet with water in the rinse section after pickling, and then drain the water. This prevents the pickling bath from mixing with the electric Ni-W alloy plating bath, which will be described later. Note that pickling must be performed before electric Ni-W alloy plating.

[0068] (S3 Electric Ni-W alloy plating) Next, the Ni-plated steel sheet pickled under the above-mentioned conditions is subjected to electric Ni-W alloy plating. As a result, a Ni-W alloy layer 13 is provided on the surface of the Ni-plated steel sheet, as shown in Fig. 4. The plated steel sheet obtained by electric Ni-W alloy plating is hereinafter referred to as a multi-layer plated steel sheet.

[0069] (S4 Annealing) Next, the multi-layer plated steel sheet (i.e., the base steel sheet 11 having the Ni plating layer and the Ni-W alloy layer 13 disposed thereon) is annealed. As a result, as shown in Fig. 4, Fe of the base steel sheet 11 is diffused into a part of the plating layer to form an Fe diffused alloy layer 14. In this way, a surface-treated steel sheet 1 can be obtained which includes the base steel sheet 11, the Ni-containing layer 12 disposed on the surface of the base steel sheet 11, and the Ni-W alloy layer 13 disposed on the surface of the Ni-containing layer 12, and in which the Ni-containing layer 12 has the Fe diffused alloy layer 14.

[0070] In the annealing, the annealing temperature is set to 630 to 860° C., and the annealing time is set to 10 to 180 seconds, whereby the Ni—W alloy layer 13 can be made porous.

[0071] The present inventors presume that the reason why the Ni-W alloy layer 13 can be made porous by setting the pickling conditions and annealing conditions within the above-mentioned ranges is as follows. During electroplating, metal ions contained in the plating bath are electrodeposited on the substrate surface, and at the same time, hydrogen ions contained in the plating bath are taken into the plating layer. The present inventors presume that this hydrogen forms voids B during annealing.

[0072] However, the present inventors have found that the Ni-containing layer 12 needs to be pickled under the above-mentioned conditions before the electric Ni-W alloy plating. The present inventors presume that pickling under appropriate conditions removes the oxide film on the surface of the Ni-containing layer 12, making it easier for hydrogen contained in the Ni-containing layer 12 to diffuse into the Ni-W alloy layer 13. On the other hand, when the sulfuric acid concentration in the pickling is insufficient or the immersion time is short, the oxide film on the surface of the Ni-containing layer 12 is not sufficiently removed, which the present inventors presume prevents hydrogen contained in the Ni-containing layer 12 from diffusing into the Ni-W alloy layer 13.

[0073] The present inventors also presume that when the Ni plating contains W, W affects the behavior of hydrogen. Furthermore, the present inventors presume that by making the Ni plating contain W and setting the annealing conditions within the above-mentioned range, hydrogen supplied from the Ni-containing layer 12 to the Ni-W alloy layer 13 forms a large number of voids B in the Ni-W alloy layer 13, thereby making the Ni-W alloy layer 13 porous.

[0074] The above describes the most basic aspect of the method for producing the surface-treated steel sheet 1 according to this embodiment. Next, a more preferred aspect of the method for producing the surface-treated steel sheet 1 according to this embodiment will be described.

[0075] (Bath ingredients) The Ni plating bath used in the electric Ni plating contains Ni as a main component. For example, the proportion of Ni element contained in the plating bath to all metal elements contained in the plating bath may be 95 mass% or more, 96 mass% or more, or 97 mass% or more. In addition to Ni, the Ni plating bath may contain Cr, Mo, etc.

[0076] The Ni-W plating bath used in the electric Ni-W alloy plating contains Ni and W as main components. For example, the ratio of the W element contained in the plating bath to all metal elements contained in the plating bath may be within the range of 10 to 60 mass%. Also, for example, the ratio of the total of the Ni element and the W element contained in the plating bath to all metal elements contained in the plating bath may be 95 mass% or more, 96 mass% or more, or 97 mass% or more. In addition to Ni and W, the Ni-W plating bath may contain Cr, Mo, etc.

[0077] (Ni deposition amount) In the Ni electroplating and Ni-W alloy electroplating, the Ni coating weight is not particularly limited, but is, for example, 1.8 to 35.6 g / m 2 As a result, the Ni deposition amount in the Ni-containing layer 12 and the Ni-W alloy layer 13 may be 1.8 to 35.6 g / m 2The more preferable Ni coating weight may be the same as the more preferable Ni coating weight in the surface-treated steel sheet 1 according to the present embodiment described above. The Ni coating weight can be controlled via the components of the plating bath and the amount of current.

[0078] Additionally, the various aspects described with respect to the surface-treated steel sheet 1 according to the present embodiment can be applied to the manufacturing method of the surface-treated steel sheet according to the present embodiment. For example, it goes without saying that the preferred aspects of the base steel sheet 11 in the surface-treated steel sheet 1 according to the present embodiment can be applied to the manufacturing method of the surface-treated steel sheet according to the present embodiment.

[0079] (3. Manufacturing method of battery components) Next, a method for manufacturing a battery component according to another embodiment of the present invention will be described. The method for manufacturing a battery component according to this embodiment includes a step of resistance welding a tab and a surface-treated steel sheet 1, and the surface-treated steel sheet 1 is the surface-treated steel sheet 1 according to this embodiment. The resistance welding is, for example, spot welding.

[0080] The surface-treated steel sheet 1 according to the present embodiment has a high surface resistance and an appropriate current value for resistance welding with the tab is low. Therefore, in the resistance welding of the surface-treated steel sheet 1 according to the present embodiment, there is little risk of the tab being damaged by an overcurrent. Therefore, the battery component manufacturing method according to the present embodiment can suitably manufacture the battery component.

[0081] Although the resistance welding conditions are not particularly limited, it is preferable that the welding voltage in the resistance welding is 2.0 V to 3.5 V and the current application time is 1.0 ms to 10.0 ms, for example, which can further suppress poor bonding between the tab and the surface-treated steel sheet 1 and breakage of the tab. EXAMPLES

[0082] The effects of one embodiment of the present invention will be explained more specifically with reference to an example. However, the conditions in the example are merely an example of conditions adopted to confirm the feasibility and effects of the present invention. The present invention is not limited to this example of conditions. Various conditions may be adopted in the present invention as long as they do not deviate from the gist of the present invention and the object of the present invention is achieved.

[0083] (Experiment 1) Various surface-treated steel sheets were prepared by subjecting base steel sheets to Ni electroplating, pickling, Ni-W alloy electroplating, and annealing. The components of the base steel sheets are shown in Table 1. The components of the plating bath used in the Ni-W alloy electroplating are shown in Table 2. The manufacturing conditions of the surface-treated steel sheets are shown in Table 3. The evaluation results of the surface-treated steel sheets are shown in Table 4. In Tables 3 and 4, values ​​outside the range of this embodiment are underlined. Note that conditions not listed in the tables were the same in all examples, and their details are as follows:

[0084] The components of the plating bath for electric Ni plating were NiSO4·6H2O: 230g / L and H3BO3: 45g / L. The pH of the plating bath for electric Ni plating was 4, and the temperature was 50°C. The current density for electric Ni plating was 30A / dm 2 The plating weight in the Ni electroplating was controlled by adjusting the current flow time.

[0085] In the pickling after the Ni electroplating, the Ni-plated steel sheet was immersed in a 85 g / L sulfuric acid bath for 30 seconds, then rinsed with water and drained.

[0086] The Ni ion source for electric Ni-W alloy plating was NiSO4·6H2O, and the W ion source was Na2WO4·2H2O. The composition (W content) of the Ni-W alloy plating was adjusted by changing the ratio of Ni ion concentration and W ion concentration. In addition, 0.5 mol / L of citric acid was added to the plating bath for electric Ni-W alloy plating to stabilize the W ions in the bath. The pH of the plating bath for electric Ni-W alloy plating was 6, and the temperature was 50°C. The current density for electric Ni-W alloy plating was 20 A / dm 2The plating weight in the electric Ni-W alloy plating was controlled by adjusting the current flow time.

[0087] The presence or absence of porosity in the Ni-W alloy layer was determined by the above-mentioned method using a STEM-equipped FE-SEM capable of elemental analysis by EDS. The determination results are shown in Table 4.

[0088] The average W concentration in the Ni-W alloy layer was measured by the above-mentioned method using XPS. The measurement results are shown in Table 4.

[0089] The thickness of the Ni-W alloy layer and the thickness of the Fe-diffused alloy layer were measured by the above-mentioned method using GDS. The measurement results are shown in Table 4.

[0090] The weldability was evaluated by the following procedure. Each sample was welded to a tab (material and size: nickel thin film 10 x 100 x 0.01 mm). The welding voltage was 2.5 V and the current time was 5.0 ms. After welding, the degree of bonding between the tab and the steel plate was visually evaluated. The evaluation criteria were as follows: 1: No poor bonding or broken tabs 2: No bond failure or damage to the tab, but discoloration of the sample or tab is observed 3: Poor connection or broken tab

[0091] [Table 1]

[0092] [Table 2]

[0093] [Table 3]

[0094] [Table 4]

[0095] In the test pieces of Examples 4, 5, and 8, the Ni-W alloy layer was not porous. The weldability of these test pieces was poor. In the production of Example 4, the annealing time was insufficient. In the production of Example 5, the annealing temperature was excessive and the annealing time was insufficient. In the production of Example 8, pickling was not performed. The present inventors presume that in Examples 4, 5, and 8, the porous Ni-W alloy layer was not obtained due to inappropriate production conditions.

[0096] On the other hand, the Ni-W alloy layer of the specimens obtained by the proper manufacturing method was porous.The weldability of these specimens was good.

[0097] (Experiment 2) Various surface-treated steel sheets were prepared by subjecting the base steel sheet to Ni electroplating, pickling, Ni-W alloy electroplating, and annealing. The pickling conditions were as shown in Table 5. The manufacturing conditions other than the pickling conditions were the same as those of Example 1 disclosed in Tables 3 and 4.

[0098] [Table 5]

[0099] The surface-treated steel sheets manufactured by the above-mentioned procedure were evaluated in the same manner as in Experiment 1. The evaluation results are shown in Table 6.

[0100] [Table 6]

[0101] The manufacturing conditions of Examples 101 to 105 were the same as those of Example 1, except for the pickling conditions. However, unlike Example 1, the Ni-W alloy layers of the test pieces of Examples 101 to 105 were not porous. Unlike Example 1, the weldability of the test pieces of Examples 101 to 105 was inferior.

[0102] In Examples 101 and 103, the sulfuric acid concentration of the pickling bath was insufficient. It is presumed that, in Examples 101 and 103, the oxide film on the surface of the Ni-containing layer was not sufficiently removed, and the Ni-W alloy layer was not made porous. In Example 103, instead of lowering the sulfuric acid concentration of the pickling bath, hydrochloric acid was added to the bath. However, even when a bath containing hydrochloric acid was used, it was not possible to obtain a surface-treated steel sheet having good weldability like Example 1. It is presumed that the reason for this is that hydrochloric acid has a poor pickling effect compared to sulfuric acid.

[0103] In Example 102, the sulfuric acid concentration in the pickling bath was excessive, and the Ni-W alloy layer in Example 102 was not made porous.

[0104] The effect of an excessive sulfuric acid concentration on the Ni-W alloy layer is unclear, but the present inventors presume as follows. When the sulfuric acid concentration is excessive, the surface of the Ni-containing layer becomes finely uneven. When a Ni-W alloy layer is provided on this, the interface area between the Ni-containing layer and the Ni-W alloy layer becomes large. It is generally believed that diffusible hydrogen is easily trapped at the interface of a plating layer. The present inventors presume that the increase in the interface area reduces the amount of diffusible hydrogen in the Ni-W alloy layer, preventing the Ni-W alloy layer from becoming porous due to diffusible hydrogen.

[0105] In Example 104, the base steel sheet having the Ni-plated layer was immersed in the pickling bath for an insufficient time, which is presumably why the oxide film on the surface of the Ni-containing layer was not sufficiently removed in Example 104, and the Ni-W alloy layer was not made porous.

[0106] In Example 105, the base steel sheet having a Ni-plated layer was immersed in the bath for an excessive amount of time during pickling. As a result, the Ni-W alloy layer was not made porous in Example 105. The effect of excessive pickling time on the Ni-W alloy layer is unclear, but the present inventors presume that the same phenomenon as in the example in which the sulfuric acid concentration was excessive occurred. That is, it is presumed that excessive pickling expanded the area of ​​the interface between the Ni-containing layer and the Ni-W alloy layer, preventing the Ni-W alloy layer from being made porous by diffusible hydrogen. [Explanation of symbols]

[0107] 1. Surface-treated steel sheets 11 Base steel plate 12 Ni-containing layer 13 Ni-W alloy layer 14 Fe diffusion alloy layer B Void

Claims

1. A base steel plate; A Ni-containing layer disposed on a surface of the base steel sheet; A Ni-W alloy layer disposed on a surface of the Ni-containing layer; Equipped with The Ni-containing layer has an Fe diffusion alloy layer, The Ni—W alloy layer is porous. Surface treated steel sheet.

2. The average W concentration in the Ni--W alloy layer is 10 to 45 mass %. The surface-treated steel sheet according to claim 1 .

3. The thickness of the Ni--W alloy layer is 0.01 to 2.0 μm. The surface-treated steel sheet according to claim 1 or 2.

4. The Ni-containing layer and the Ni-W alloy layer have a Ni coating weight of 1.8 to 35.6 g / m ２ is The surface-treated steel sheet according to claim 1 or 2.

5. The thickness of the Fe diffusion alloy layer is 0.1 to 3.0 μm. The surface-treated steel sheet according to claim 1 or 2.

6. Only a portion of the Ni-containing layer is the Fe diffusion alloy layer. The surface-treated steel sheet according to claim 1 or 2.

7. The entire Ni-containing layer is the Fe diffusion alloy layer, and a part of the Ni-W alloy layer is the Fe diffusion alloy layer. The surface-treated steel sheet according to claim 1 or 2.

8. The present invention includes a step of resistance welding a tab and the surface-treated steel sheet according to claim 1 or 2. Manufacturing method for battery components.

9. The welding voltage in the resistance welding is set to 2.0 V to 3.5 V. The current application time in the resistance welding is set to 1.0 ms to 10.0 ms. The method for manufacturing a battery component according to claim 8 .

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