Nickel plated metal material, electrode substrate for electrolysis, electrode for electrolysis, and electrolytic cell.

Abstract

To provide a nickel-plated metal material for water electrolysis capable of suppressing damage to a diaphragm while maintaining a suitable gas generation surface area.SOLUTION: A nickel-plated metal material comprising a sheet-shaped metal base material having a plurality of opening portions, and a roughened nickel layer provided on at least one surface of the metal base material, wherein Δ Rzjis on the surface on the side of the roughened nickel layer is 4.0 μm or less, and the developed area ratio Sdr on the surface on the side of the roughened nickel layer is 15.0% or more. Where Δ Rzjis represents a difference between a ten point-average roughness Rzjis1 of an end portion of the opening portion and a ten point-average roughness Rzjis2 of a central portion of two adjacent opening portions.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a nickel-plated metal material, an electrode substrate for electrolysis, an electrode for electrolysis, and an electrolytic cell. [Background technology]

[0002] In recent years, demand for hydrogen produced using renewable energy (so-called green hydrogen) has been increasing. One method for producing green hydrogen is water electrolysis (water electrolysis), which uses power generated by natural energy sources such as wind or solar power. In water electrolysis, oxygen is generated at the anode and hydrogen is generated at the cathode by passing an electric current through water. There are several known methods for water electrolysis, including alkaline water electrolysis (AWE type), polymer electrolyte membrane (PEM type), and high-temperature steam electrolysis (SOFC type). Of these, alkaline water electrolysis has a long track record of commercial long-term operation, due to its suitability for large-scale facilities and its low cost of operation compared to other methods.

[0003] In alkaline water electrolyzers, a design specification known as the "zero gap" (hereinafter also referred to as the zero gap system) is known, in which a mesh or porous electrode with a structure that allows gas to escape to the back side is installed by pressing it against a diaphragm. This zero gap system sandwiches the diaphragm between the cathode and anode. In these technologies, there has been a demand for an increase in the electrode surface area on the cathode and anode side to increase the area where hydrogen and oxygen are generated. There has also been a demand for an increase in the electrode surface area on the anode side to reduce oxygen overvoltage and save power.

[0004] For example, Patent Document 1 discloses a method for producing a LaNi x Nb y O 3-z (x+y is 0.8 or more and 1.2 or less, y is 0 or more and 0.2 or less, z is -0.5 or more and 0.5 or less), and the nickel substrate and LaNi x Nb y O 3-zAn electrode is disclosed in which the ratio of (extension length from one end of the interface to the other end) / (linear distance from one end of the interface to the other end) at the interface between the layers is 1.5 or more and 3 or less. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2022-149959 Summary of the Invention [Problem to be solved by the invention]

[0006] The electrode disclosed in Patent Document 1 attempts to increase the gas generation rate and improve adhesion to the catalyst by increasing the surface area through blasting. However, when using an electrode substrate that has been blasted, it is difficult to increase the surface area to the desired level, and the desired gas generation rate cannot be obtained. In addition, the blasting process generates metal powder, making it economically unreasonable.

[0007] The present disclosure has been made in view of the above-mentioned conventional circumstances, and has an object to provide a nickel-plated metal material for water electrolysis having an increased gas generation surface area. [Means for solving the problem]

[0008] In order to solve the above problems, the nickel-plated metal material of this embodiment includes (1) a sheet-like metal substrate having a plurality of apertures and a roughened nickel layer provided on at least one surface of the metal substrate, wherein ΔRzjis on the surface facing the roughened nickel layer is 4.0 μm or less, and a developed area ratio Sdr on the surface facing the roughened nickel layer is 15.0% or more, where ΔRzjis represents the difference between the ten-point mean roughness Rzjis1 of the edge of the aperture and the ten-point mean roughness Rzjis2 of the center of two adjacent apertures.

[0009] The electrode for electrolysis (hereinafter referred to as "electrode") or electrode base material for electrolysis (hereinafter referred to as "electrode base material") of this embodiment is characterized by being made of the above-mentioned nickel-plated metal material. Furthermore, the electrolytic cell of this embodiment is characterized by using the above-mentioned electrode as a cathode or an anode. [Effects of the Invention]

[0010] According to the present disclosure, it is possible to provide a nickel-plated metal material having a suitable gas generation surface area when applied to an electrode or electrode base material for electrolysis in an electrolytic cell, particularly to a zero-gap alkaline electrolytic cell. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a plan view schematically showing one embodiment of a nickel-plated metal material. FIG. [Figure 2A] FIG. 2 is a schematic cross-sectional view taken along the line AA′ in FIG. [Figure 2B] FIG. 2B is an enlarged view of the area enclosed by the dotted line in FIG. 2A. [Figure 2C] FIG. 2 is a schematic diagram for explaining the measurement range of the ten-point average roughness. [Figure 3] FIG. 2 is a schematic diagram showing the positional relationship between a nickel-plated metal material and a diaphragm. [Figure 4] FIG. 10 is a cross-sectional view schematically showing another embodiment of a nickel-plated metal material. [Figure 5] FIG. 1 is a schematic diagram showing an example of an alkaline water electrolytic cell to which a nickel-plated metal material can be applied. [Figure 6A] FIG. 2 is a schematic diagram of an apparatus used to evaluate the amount of gas generated from the nickel-plated metal material of the present embodiment. [Figure 6B] FIG. 2 is a schematic diagram of an apparatus used to evaluate the amount of gas generated from the nickel-plated metal material of the present embodiment. [Figure 7] FIG. 1 is a schematic diagram showing a pressure sensitivity test method for nickel-plated metal materials. DETAILED DESCRIPTION OF THE INVENTION

[0012] First Embodiment A first embodiment for carrying out the nickel-plated metal material of the present disclosure will be described below. FIG. 1 is a plan view schematically illustrating one embodiment of a nickel-plated metal material 100 of this embodiment. FIGS. 2A to 2C are cross-sectional views taken along the line A-A' in FIG. 1 . As shown in FIG. 2 , the nickel-plated metal material 100 of this embodiment includes a sheet-like substrate 20 made of metal and having apertures, and a roughened nickel layer 50 provided on the substrate 20. While the roughened nickel layer 50 is shown standing upright on the paper in FIG. 1 , it is not shown. While the roughened nickel layer 50 is shown standing upright in the Z direction in FIGS. 2A and 2C , it is not shown. The nickel-plated metal material 100 of this embodiment is preferably used as an electrode or electrode substrate for electrolysis, particularly as an electrode or electrode substrate for an alkaline water electrolytic cell, and is particularly preferably used as a zero-gap electrode or electrode substrate.

[0013] <Base material 20> As shown in FIGS. 1 and 2A to 2C, the substrate 20 used in the nickel-plated metal material 100 of this embodiment is sheet-shaped and has a plurality of openings H formed therein. In FIG. 1, four openings H are regularly arranged in the X direction and two in the Y direction within the substrate 20, but this arrangement is not limited thereto. That is, the openings H may be arranged regularly or randomly. The shape of the openings H is not limited to a rectangle, and any known shape, such as a square, ellipse, or perfect circle, may be appropriately selected. In other words, the substrate 20 may be made of a known lattice plate, mesh, a porous material pressed using a punching press or rotary press, expanded metal, wire mesh, or the like. The size (length and width) of the substrate 20 can also be appropriately set depending on the application. The porosity of the substrate 20 is preferably 10 to 90%, more preferably 20 to 80%, and particularly preferably 30 to 70%. In this embodiment, the porosity of the substrate 20 is the same as the porosity of the nickel-plated metal material 100. When used in the zero-gap method, if the porosity of the nickel-plated metal material 100 is too small, gas generated on the electrode surface during electrolysis is less likely to dissipate, which may result in an increase in electrode voltage. If the porosity is too large, the area in which the roughened nickel layer is formed is reduced, making it difficult to achieve the effect of increasing the surface area.

[0014] The metal material of the substrate 20 is preferably a metal material made of a pure metal selected from Fe, Al, and Ni, or a metal material made of an alloy based on one selected from Fe, Al, and Ni. From the viewpoints of strength and corrosion resistance, steel plate, Ni, Ni alloy material, etc. are particularly preferred. As the steel plate, stainless steel plate or iron-based steel plate containing less than 1.0 wt.% of Cr and other additive metal elements is preferred. Specifically, as the carbon steel plate, low-carbon steel (carbon content 0.01 to 0.15 wt.%), such as low-carbon aluminum-killed steel, ultra-low-carbon steel with a carbon content of less than 0.01 wt.%, or non-aging ultra-low-carbon steel obtained by adding Ti, Nb, or the like to ultra-low-carbon steel are preferred. From the viewpoint of electrical conductivity, low-carbon steel plate and ultra-low-carbon steel plate are preferred. Surface-treated steel plate having an iron-nickel diffusion layer or an iron-nickel diffusion layer and a nickel layer on the surface of the steel plate can also be used, as will be described in detail later.

[0015] The thickness of the substrate 20 used in the nickel-plated metal material 100 of this embodiment is preferably in the range of 0.01 mm to 5.0 mm, more preferably 0.03 mm to 3.0 mm, and particularly preferably 0.03 mm to 1.2 mm. Too thin a thickness is undesirable because it lacks strength against the pressure difference and pressing pressure in the electrolytic cell. Too thick a thickness is undesirable because it reduces flexibility. The thickness of the substrate 20 is preferably measured by cross-sectional observation using an optical microscope or a scanning electron microscope (SEM). Furthermore, thickness measurement using a micrometer or the like can be applied to measure the thickness before surface treatment, i.e., before the formation of the roughened nickel layer 50.

[0016] As shown in FIG. 2, the openings H in the substrate 20 are through-holes that communicate with both surfaces of the substrate 20. The cross-section of the openings H may have rounded ends (see FIG. 2), inclined or oblique surfaces (not shown), or the cross-section of the openings H may be perpendicular to the surface of the substrate 20 (not shown). FIG. 2C shows an example of the opening width h1, the opening width h20 on the surface side where the roughened nickel layer 50 described below is formed, and the opening width h10 on the opposite surface side. The opening widths h1, h10, and h20 may be approximately equal, or, in cases where the cross-section of the openings H is inclined with respect to the surface of the substrate 20, h10 and h20 may be longer than the opening width h1. The opening width of the openings H is h10.<h20であってもよいし、h10> Furthermore, although not shown, the cross section of the opening H may be curved relative to the surface of the substrate 20.

[0017] An example of the shape and size of the opening H in the substrate 20 is described below. The opening H shown in Fig. 2 has a rectangular shape with an opening width h1 and an opening length h3 on the long side. The opening width h1 and opening length h3 may be, for example, 0.1 mm to 3.0 mm.

[0018] On the other hand, in a region (region B) of the base material 20 where the openings H are not arranged, a roughened nickel layer 50, which will be described later, is formed. More specifically, region B can be said to be a region surrounded by two adjacent openings H that are concentric along the X direction and two adjacent openings H that are concentric along the Y direction. The distance h between two adjacent openings H that are concentric along the X direction is 103 For example, the distance h between two adjacent openings H on the same center along the Y direction may be 0.1 mm to 3.0 mm. 105 For example, the thickness may be 0.1 mm to 3.0 mm.

[0019] <Roughened nickel layer 50> As shown in FIG. 2B , in the nickel-plated metal material 100 of the present disclosure, a roughened nickel layer 50 is formed on at least one surface of the substrate 20. The roughened nickel layer 50 may be formed on both surfaces of the substrate 20. More specifically, the roughened nickel layer 50 is formed mainly in region B on the substrate 20. The roughened nickel layer 50 may also be formed on the cross section in the thickness direction of the opening H. In the present disclosure, the roughened nickel layer 50 is a layer on which numerous protrusions formed by columnar aggregations of nickel particles are formed, and can be obtained by performing a nickel granular plating process, or a granular nickel plating process followed by a growth nickel plating process, as described below. The nickel-plated steel sheet of the present disclosure has a roughened nickel layer 50 formed on its surface, in which the portions forming the protrusions are made of nickel, thereby efficiently obtaining a desired surface area and achieving excellent industrial productivity. In industrially used water electrolytic cells, electrode substrates are required to have the desired width and length, and as consumables, the electrodes must be replaceable along with the electrode substrate. Therefore, industrial mass production is required. However, conventional methods using blasting, etching, and alloy film formation have problems such as metal loss during the manufacturing process, limitations on the applicable size, and the long film formation time, making it difficult to achieve the desired increase in surface area. In contrast, the roughened nickel layer of the present disclosure has nickel as the central portion of the protrusions forming the roughened shape, allowing for an increase in surface area over a wide area in a short period of time. This makes it suitable for use as an electrode or electrode substrate for electrolysis. Note that, when nickel is used in the growth nickel plating described below, the entire roughened nickel layer is made of nickel. Alternatively, the roughened nickel layer may be formed by forming a nickel-containing alloy coating layer on the surface of protrusions formed by granular nickel plating, either by growth nickel plating or by sputtering after granular nickel plating. Examples of alloy coating layers containing nickel include FeNi alloys, NiCo alloys, FeNiW alloys, NiMo alloys, NiB alloys, NiW alloys, NiSn alloys, and FeNiSn alloys.

[0020] In the nickel-plated metal material 100 of the present disclosure, the gas generation surface area can be increased by the roughened nickel layer 50. On the other hand, when openings H are present in the base material 20 as in the present disclosure, and a roughened nickel layer is formed in region B by plating as described above, it has been found that the protrusion height of the roughened nickel layer 50 tends to be higher at the end of region B (hereinafter also referred to as the end) near the openings than at the center of region B (hereinafter also referred to as the center).

[0021] When the nickel-plated metal material 100 of the present disclosure is applied to an electrode or electrode substrate in a zero-gap alkaline electrolytic cell, as shown in FIG. 3 , the surface on which the roughened nickel layer 50 is formed is positioned adjacent to the diaphragm Dp of the alkaline electrolytic cell. If the protrusion heights of the roughened nickel layer 50 vary, the higher protrusions may preferentially contact the diaphragm Dp, potentially concentrating stress. Contact with the diaphragm Dp and stress concentration may result in damage to the diaphragm, potentially increasing the frequency of diaphragm replacement and reducing diaphragm performance. Furthermore, the roughened portion in contact with the diaphragm Dp may fall off, potentially causing problems such as short circuits during water electrolysis or drifting in the electrolytic solution as floating particles, potentially reducing electrolysis efficiency. Meanwhile, the lower protrusion height portions of the roughened nickel layer 50 may create gaps Ga between the diaphragm Dp and the diaphragm Dp, potentially reducing electrolysis efficiency.

[0022] Based on the above trends, the inventors investigated the balance between the effect on the diaphragm and the electrolysis efficiency, and found that the above-mentioned damage to the diaphragm and the decrease in electrolysis efficiency can be suppressed by setting ΔRzjis to a predetermined value or less on the surface of the roughened nickel layer side. Furthermore, they found that by controlling both ΔRzjis and the developed area ratio Sdr, a nickel-plated metal material can be obtained that satisfies the balance between the amount of gas generated, damage to the diaphragm, and electrolysis efficiency.

[0023] In the present disclosure, the above-mentioned ΔRzjis represents the difference between the ten-point mean roughness Rzjis1 of the edge portion and the ten-point mean roughness Rzjis2 of the center portion. The present disclosure is characterized in that this ΔRzjis is 4.0 μm or less. The above-mentioned developed area ratio Sdr is 15.0% or more on the surface of the nickel-plated metal material 100 on the side of the roughened nickel layer 50.

[0024] The methods for measuring and calculating the ten-point mean roughness Rzjis1 of the edge portion, the ten-point mean roughness Rzjis2 of the central portion, the difference ΔRzjis between them, and the developed area ratio Sdr are described below. The surface texture parameters (including Rzjis and Sdr) of the surface of the roughened nickel layer 50 can be measured using a known laser microscope or the like in accordance with JIS B0601-2013 and ISO25178-2:2012.

[0025] The above-mentioned Rzjis1 and Rzjis2 will be explained. First, the ten-point mean roughness Rzjis2 of the central portion is the ten-point mean roughness measured in the central portion of the above-mentioned region B, and is the ten-point mean roughness between two adjacent openings H. More specifically, the ten-point mean roughness Rzjis2 is calculated by dividing the length h 103 The ten-point average roughness Rzjis2 is measured in a predetermined area (for example, an area of ​​128 μm × 128 μm) including the center (midpoint) of the 103 and length h 105 It may be measured in the area including the point where

[0026] The ten-point average roughness Rzjis2 of the central portion can contribute to improving the gas generation area. The ten-point average roughness Rzjis2 of the central portion is preferably 1.0 μm or more, more preferably 1.2 μm or more. There is no particular upper limit to the ten-point average roughness Rzjis2 of the central portion, but it is preferably 12.0 μm or less in order to satisfy ΔRzjis of 4.0 μm or less. From the viewpoint of gas generation efficiency, Rzjis2 is preferably more than 4.5 μm and 12.0 μm or less, and more preferably more than 4.5 μm and 10.0 μm or less. On the other hand, when considering high long-term durability, Rzjis2 is preferably 1.0 μm to 4.5 μm, and more preferably 1.2 μm to 4.5 μm.

[0027] On the other hand, the ten-point mean roughness Rzjis1 of the end portion is the ten-point mean roughness measured in region B near the boundary between region B and the opening H. More specifically, the ten-point mean roughness Rzjis1 is measured in a predetermined region (e.g., a 128 μm × 128 μm region) from the aforementioned boundary toward region B. Here, when the cross section of the opening H is inclined with respect to the surface of the substrate 20, for example, as shown in FIG. 2C , when the opening width h10 or h20 is longer than the opening width h1 as viewed from the surface side of the substrate 20 as shown in FIG. 1 , the measurement region for the ten-point mean roughness Rzjis1 can be determined as follows: When measuring the surface texture of the nickel-plated metal material 100, the measurement region is determined from above, and first, point C, which forms the boundary with the opening, is determined in region B. As shown in FIG. 2C , point C may be determined as the portion with the narrowest opening width in the cross section of the opening H. It is preferable to set the starting point of the measurement region for ten-point average roughness Rzjis1 at a point moved from point C toward region B within a range of 1 to 10% of the length of h103, and then set a predetermined region toward the center from there as the measurement region for ten-point average roughness Rzjis1. It is preferable that the measurement region for ten-point average roughness Rzjis1 has a gentle slope on the surface of region B, and the image does not defocus too much in the measurement region.

[0028] Furthermore, when measuring the ten-point mean roughness Rzjis1, if the shape of the opening H is rectangular as shown in Figure 1, measurements may be taken at both the side and corner parts of the opening H, and the value which differs more from the ten-point mean roughness Rzjis2 of the center as described above may be used as the ten-point mean roughness Rzjis1 of the end part. Similarly, even if the shape of the opening H is elliptical, the value which differs more from the ten-point mean roughness Rzjis2 of the center, out of the ten-point mean roughnesses at the end part of the major axis radius and the end part of the minor axis radius, may be used as the ten-point mean roughness Rzjis1 of the end part. In cases such as when the shape of the opening H is perfectly circular, the average value of the ten-point mean roughnesses of multiple arbitrary locations on the opening H may be used as the ten-point mean roughness Rzjis1 of the end part.

[0029] There are no particular restrictions on the numerical range of the ten-point average roughness Rzjis1 of the edge as long as ΔRzjis and Sdr are satisfied, but a range of 0.1 μm to 15.0 μm is preferred in order to satisfy the requirement that ΔRzjis be 4.0 μm or less.

[0030] The nickel-plated metal material in this embodiment is characterized in that the surface on the roughened nickel layer 50 side has an developed area ratio Sdr of 15.0% or more. By setting the developed area ratio Sdr, i.e., the area increase rate due to the formation of the roughened nickel layer relative to the area of ​​the defined region, to 15.0% or more, a nickel-plated metal material can be obtained that can solve both the problem of the amount of gas generated and the problem of suppressing the influence on the diaphragm. From the viewpoint of being able to increase the amount of gas generated, a developed area ratio Sdr of 20.0% or more is more preferable. Furthermore, by setting the developed area ratio Sdr to exceed 200.0%, a further improvement in the gas generation area can be expected. On the other hand, the upper limit of the developed area ratio Sdr is preferably about 300.0%.

[0031] In the nickel-plated metal material of this embodiment, the maximum height Sz, which is a surface texture parameter, on the surface facing the roughened nickel layer 50 is preferably less than 25.0 μm. If Sz is too high, there is a possibility that protrusions with a high height will be formed, and therefore it is more preferable that it is less than 23.0 μm. From the viewpoint of being able to significantly suppress the above-mentioned damage to the diaphragm, it is particularly preferable that the maximum height Sz is less than 10.0 μm. On the other hand, the lower limit of the maximum height Sz is not particularly limited, but is preferably 1.5 μm, more preferably 3.0 μm, and even more preferably 4.0 μm.

[0032] In the nickel-plated metal material 100 of this embodiment, the amount of nickel deposited in the roughened nickel layer 50 is set to 2.0 g / m from the viewpoint of controlling the amount of gas generated and ΔRzjis. 2 ~27.0g / m 2 The amount of nickel deposited can be measured by ICP (Inductively Coupled Plasma) or the like.

[0033] In this embodiment, the method for measuring the nickel deposition amount of the roughened nickel layer 50 can be, for example, the methods described in International Publication No. 2020 / 017655 and International Publication No. 2021 / 020338. That is, the total nickel amount can be determined by measuring the nickel deposition amount of the nickel-plated metal material 100 using inductively coupled plasma (ICP) instead of X-ray fluorescence analysis (XRF) while also using a cross-sectional observation image obtained with a scanning electron microscope (SEM) or the like.

[0034] <Nickel base plating layer> The nickel-plated metal material 100 in this embodiment may have an undercoat nickel plating layer 30 (not shown) between the substrate 20 and the roughened nickel layer 50. The undercoat nickel plating layer 30 may be a nickel layer that can be formed, for example, using a known Watts bath on at least one surface of the substrate 20. The configuration disclosed in WO2021 / 020338 and the like can be applied as appropriate to the undercoat nickel plating layer 30.

[0035] The following describes the overall thickness of the nickel-plated metal material 100 in this embodiment. Note that the "thickness of the nickel-plated metal material 100" in this embodiment can be measured by cross-sectional observation with a scanning electron microscope (SEM) or by using a micrometer.

[0036] The overall thickness of the nickel-plated metal material 100 in this embodiment is preferably in the range of 0.02 mm to 5.02 mm, more preferably 0.05 mm to 3.02 mm, and particularly preferably 0.05 mm to 1.22 mm.

[0037] As described above, when the nickel-plated metal material 100 of this embodiment is used as an electrode or electrode substrate for an electrolytic cell, it can achieve a balance between the amount of gas generated and the efficiency of electrolysis. In particular, when used as an electrode or electrode substrate for an alkaline water electrolytic cell, it is preferable because it can achieve a balance between the amount of gas generated, damage to the diaphragm, and the efficiency of electrolysis.

[0038] Second Embodiment Next, a second embodiment for carrying out the nickel-plated metal material of the present disclosure will be described with reference to Fig. 4. Fig. 4 is a schematic diagram showing a cross section of a nickel-plated metal material 200 of the second embodiment. The nickel-plated metal material 200 differs from the first embodiment described above in that the substrate 25 does not have a plurality of openings H. Therefore, these differences will be mainly described below, and other features will be assigned common reference numerals and will not be described again.

[0039] The substrate 25 in the nickel-plated metal material 200 of this embodiment may be the same as that of the first embodiment described above, except that it does not have the openings H. That is, the substrate 25 may be a metal plate or metal foil having a thickness of 0.01 to 0.5 mm, and the metal material may be a pure metal or alloy selected from Fe, Al, and Ni.

[0040] In this embodiment, a roughened nickel layer 55 is formed on at least one surface of the base material 25. The roughened nickel layer 55 can increase the gas generation surface area of ​​the nickel-plated metal material 200. More specifically, by making the ten-point mean roughness Rzjis of the surface on the roughened nickel layer 55 side 1.0 μm or more and 12.0 μm or less and making the developed area ratio Sdr of the surface on the roughened nickel layer 55 side 15.0% or more, a preferable amount of gas generation can be obtained when the nickel-plated metal material 200 is used as an electrode in an alkaline electrolytic cell. From the viewpoint of preventing scratches on the diaphragm, etc., it is preferable that the maximum height Sz of the surface on the roughened nickel layer 55 side be less than 10 μm.

[0041] <Method for manufacturing nickel-plated metal materials> A method for manufacturing a nickel-plated metal material will be described below. The method for manufacturing a nickel-plated metal material of the first or second embodiment described above is characterized by including a roughened nickel plating step of forming a roughened nickel layer 50 on at least one surface of a sheet-like metal substrate. The sheet-like metal substrate may have a plurality of apertures. That is, the nickel metal material of the first embodiment is characterized by including, in this order, a step of preparing a sheet-like metal substrate having a plurality of apertures, and a step of roughened nickel plating the metal substrate. The roughened nickel plating step of forming the roughened nickel layer 50 may include a "granular nickel formation plating step" described below, or may include a "nickel growth plating step" in addition to the "granular nickel formation plating step." The "granular nickel formation plating step" is performed by applying a current having an average current density of 15.0 A / dm 2 More than 18.0A / dm is preferable. 2 More preferably, 20.0 A / dm 2 Furthermore, the "granular nickel forming plating step" may be a step of performing roughened nickel plating using a circulating bath at a bath temperature of 50°C or higher and at a flow rate of more than 1 L / min for a plating solution with a volume of, for example, 2 L.

[0042] The method for producing a nickel-plated metal material of this embodiment may include a step of forming a nickel layer by plating nickel on the substrate 20 (hereinafter also referred to as a "base nickel plating step") prior to the above-mentioned roughening nickel plating step. Examples of base nickel plating conditions in the base nickel plating step are shown below.

[0043] [Example of nickel plating bath (Watts bath) and plating conditions] ·Bath composition: Nickel sulfate hexahydrate: 200~300g / L Nickel chloride hexahydrate: 20-60g / L Boric acid: 10-50g / L Bath temperature: 40~70℃ pH: 3.0 to 5.0 Agitation: Air agitation or jet agitation Current density: 5~30A / dm2 In addition to the Watts bath, known nickel sulfamate baths and citric acid baths may also be used as the bath composition. Furthermore, known additives such as brighteners may be added to the plating bath to produce bright nickel plating or semi-bright nickel plating.

[0044] The plating bath in the granular nickel formation plating step preferably has a chloride ion concentration of 3 to 90 g / L, more preferably 3 to 75 g / L, and even more preferably 3 to 50 g / L, a nickel ion to ammonium ion weight ratio of "nickel ion / ammonium ion" of preferably 0.05 to 0.75, more preferably 0.05 to 0.60, even more preferably 0.05 to 0.50, and even more preferably 0.05 to 0.30, and a bath conductivity at 50°C of preferably 5.00 to 30.00 S / m, more preferably 5.00 to 20.00 S / m, and even more preferably 7.00 to 20.00 S / m. Note that when the chloride ion concentration is 10 g / L or more, a good roughened plating state is easily achieved even if the deposition amount of the roughened nickel plating is small. The method for adjusting the chloride ion concentration, the ratio of nickel ions to ammonium ions, and the bath conductivity of the plating bath to fall within the above ranges is not particularly limited, but an example thereof includes a method in which the plating bath contains nickel sulfate hexahydrate, nickel chloride hexahydrate, and ammonium sulfate, and the amounts of these components mixed are appropriately adjusted. An example of plating conditions is as follows.

[0045] [Granular nickel formation plating conditions] bath composition Nickel sulfate hexahydrate 10-100g / L, nickel chloride hexahydrate 1-90g / L, ammonium sulfate 10-130g / L pH 4.0~8.0 Bath temperature: 50°C or higher Average current density 15A / dm 2 End Plating time: 5 seconds to 150 seconds Electricity: 100~1500C / dm 2 Stirring, etc.: Circulating bath (for example, for a plating solution with a volume of 2 L, the amount of liquid circulated by the pump exceeds a flow rate of 1 L / min) Under the above conditions, the plating treatment can be carried out once or multiple times in the circulating bath so that the total amount of electricity is as described above.

[0046] The ammonia added to the nickel plating bath may be, instead of ammonium sulfate, ammonia water or ammonium chloride. The ammonium ion concentration in the plating bath is preferably 6 to 35 g / L, more preferably 10 to 35 g / L, even more preferably 16 to 35 g / L, and even more preferably 20 to 35 g / L. Hydrochloric acid, sodium chloride, potassium chloride, or the like may be used to control the chloride ion concentration.

[0047] The plating bath stirring conditions in the granular nickel formation plating process are preferably a circulating bath method in which the plating solution is circulated by a pump. Specifically, it is preferable to continuously circulate the plating solution at a rate of more than 1 L / min for a 2 L volume of plating solution. A high plating solution circulation rate is preferable when the bath temperature is high, a high plating solution circulation rate is preferable when the average current density is high, and a high plating solution circulation rate is preferable when the nickel ion concentration is low. There is no particular upper limit for the plating solution circulation rate, but it is preferably 20 L / min or less. However, in order to control the desired shape in the roughened area, plating must be performed by controlling the bath temperature, average current density, and plating solution circulation rate to appropriate conditions.

[0048] In addition, in the above plating bath, the average current density was 15 A / dm 2 By increasing the bath temperature to 50°C or higher, the formation of more plating nuclei can be promoted. The upper limit of the average current density is 50 A / dm from the viewpoint of improving the adhesion between the substrate and the roughened nickel plating layer. 2 The following is preferable. Furthermore, for example, by continuously circulating the plating solution at a rate of more than 1 L / min for a volume of 2 L, the growth of the generated plating nuclei can be promoted.

[0049] The nickel deposition amount in the granular nickel formation plating process is set to 2.0 g / m from the viewpoint of controlling the amount of gas generated and ΔRzjis. 2 ~27.0g / m 2 It is preferable that:

[0050] [Nickel growth plating conditions] Bath composition: Nickel sulfate hexahydrate 200-350g / L, nickel chloride hexahydrate 20-60g / L, boric acid 10-50g / L pH 3.0~5.0 Bath temperature 40~70℃ Current density 5~30A / dm 2

[0051] The upper limit of the nickel deposition amount in the nickel growth plating process is 7.0 g / m from the viewpoints of adhesion to other components, productivity, and manufacturing costs. 2 Preferably, it is 6.0 g / m or less, more preferably 6.0 g / m 2 or less, and more preferably 5.0 g / m 2 The lower limit is 0.2 g / m or less from the viewpoint of adhesion of the plating layer to the substrate. 2 More preferably, 0.4 g / m or more is preferable. 2 That's all.

[0052] The nickel growth plating step is not an essential step, but can be selected as appropriate to control ΔRzjis to 4.0 μm or less. More specifically, by controlling the current density and electrolysis time in the granular nickel formation step and the nickel growth plating step, it is possible to appropriately control ΔRzjis. This is because it is possible to suppress the growth of protrusions at the end portions. More specifically, it is preferable to control the value of current density x electrolysis time. In particular, it is preferable to control the current density (A / dm 2 ) × electrolysis time (seconds) is taken as A, and the current density (A / dm 2 ) × electrolysis time (seconds) is B, then B ≧ 0.0002 × A 2 -0.0428×A", it is possible to appropriately control ΔRzjis. On the other hand, when the value of current density × electrolysis time in the granular nickel formation step described above is equal to or less than a predetermined value, the nickel growth plating step does not need to be performed. As an example, when the value of current density × electrolysis time in the granular nickel formation step is 450 or less, the height of the protrusions of the obtained roughened nickel layer is low, so the growth plating step does not need to be performed.

[0053] When the metal substrate has a plurality of openings as a result of the above steps, it is preferable that the ΔRzjis of the surface of the obtained nickel-plated metal material facing the roughened nickel layer is 4.0 μm or less, and the developed area ratio Sdr of the surface of the roughened nickel layer is 15.0% or more. Here, the ΔRzjis represents the difference between the ten-point mean roughness Rzjis1 of the edge portion and the ten-point mean roughness Rzjis2 of the central portion. When the metal substrate does not have a plurality of openings, it is preferable that the ten-point mean roughness Rzjis of the surface of the roughened nickel layer is 1.0 μm or more and 12.0 μm or less, and the developed area ratio Sdr of the surface of the roughened nickel layer is 15.0% or more.

[0054] <Electrode substrate for electrolysis, electrode for electrolysis, and electrolytic cell> The electrolytic cell of the present disclosure may include an electrolysis electrode, as an anode or cathode, that uses the nickel-plated metal material 100 described above as an electrode substrate for electrolysis and that includes other necessary known components. An example of the configuration of the electrolysis cell is shown in FIG. 5, but any other known configuration may be used as appropriate. The electrolytic cell shown in FIG. 5 includes an anode (anode), a cathode (cathode), and a separator (diaphragm). The anode is housed in the anode chamber, and the cathode is housed in the cathode chamber. The anode and cathode chambers are separated by a separator. At least one of the anode and cathode electrodes uses the nickel-plated metal material 100 described above as a substrate. The electrolytic cell may also include a cushioning material, as a known component, between the conductive plate in the electrode chamber and the electrode for extracting gas generated at the electrode. The anode or cathode may also include a known catalyst layer. The nickel-plated metal material 100 may be used as either the anode or cathode, but is preferably used as the cathode from the viewpoint of improving gas generation.

[0055] Example The present invention will be described in more detail below with reference to examples. First, the measurement methods used in the examples will be described.

[0056] [Method for measuring surface texture parameters] The ten-point mean roughness (Rzjis), a surface texture parameter for the surface of the roughened nickel layer of the nickel-plated metal material, was measured using a laser microscope (Olympus, 3D Measuring Laser Microscope LEXT OLS5000). Rzjis was measured in accordance with JIS B0601:2013 using a 100x objective lens (lens name: MPLAPON50XLEXT) to obtain an analysis image with a field of view of 128 μm × 128 μm. The analysis image was then subjected to automatic noise removal and tilt correction using an analysis application. The ten-point mean roughness (Rzjis) was then calculated using line roughness measurement. Note that the analysis was performed without any filter conditions (shape removal λf, low-pass filter λs, high-pass filter λc). The average value was calculated from 15 measurements performed under the above conditions. Furthermore, the surface texture parameters of maximum height Sz and developed area ratio Sdr were also obtained in accordance with JIS B0601-2013 and ISO25178-2:2012. The measurement magnification was 100x.

[0057] [Method for measuring current value and evaluation of gas generation amount] The apparatus shown in Figures 6A and 6B was used, with the sample as the working electrode, a platinum plate as the counter electrode, and an Ag / AgCl reference electrode. The electrolyte was a room-temperature (25°C) KOH (30 wt%) solution, and the potentiostat was a Hokuto Denko Corporation "Multi-Electrochemical Measurement System HZ-Pro." The evaluation method employed was linear sweep voltammetry (LSV). Specifically, for both hydrogen and oxygen evolution evaluations, the sample was first immersed in the electrolyte for 60 minutes to stabilize it. To evaluate hydrogen evolution, the potential was then swept (cathodic polarization) at a constant rate from the natural potential (natural potential) of the sample immersed in the electrolyte to -2.0 V, recording the change in current. The sweep rate was 10 mV / s, and the current sampling interval was 100 ms. Regarding the amount of hydrogen gas generated, the current value when -1.5V was applied was read from the measurement data, and the amount of hydrogen gas generated was evaluated based on the absolute value of this current value. Note that the larger the absolute value of the current value, the larger the amount of hydrogen gas generated. To evaluate the amount of oxygen gas generated, the same procedure as above was used except that the potential was swept from the natural potential to +2.0V (anodic polarization), and the change in current value was recorded, and the amount of oxygen gas generated was evaluated based on the absolute value of the current value when +0.8V was applied. Note that the larger the absolute value of the current value, the larger the amount of oxygen gas generated. As shown in Figure 6B, the measurement diameter of the sample was φ10mm and the measurement area was 78.5mm 2 Furthermore, the opening diameter of the counter electrode was set to φ22 mm, and the opening area was set to approximately 380 mm 2 It was decided.

[0058] [Pressure sensitivity test and evaluation of damage to the diaphragm] A pressure-sensitive test was conducted to evaluate the damage to the diaphragm of the nickel-plated metal materials obtained in Examples 1, 4, and 10, and Comparative Example 1, as described below. The nickel-plated metal materials were cut into 35-mm squares, and pressure-sensitive paper was placed in contact with the surface of the roughened nickel layer, as shown in Figure 6 . The surface of the nickel-plated metal material without the roughened nickel layer was supported by an aluminum sheet. Both sides of the material were sandwiched between silicone rubber sheets or the like, and pressure was applied at 100 N for 60 seconds. After the pressure was applied, the pressure-sensitive paper was removed, and the surface that had been in contact with the roughened nickel layer was observed under a stereomicroscope. It was confirmed that the transfer density varied depending on the height of the protrusions on the roughened nickel layer. The image was then binarized, noise was removed, and the area ratio of the black areas was calculated. A smaller area ratio of the black areas was evaluated as being more likely to suppress damage to the diaphragm. The specific binarization method was as follows. First, the pressure-sensitive paper image data (640 μm × 480 μm) taken with an optical microscope was imported into graphics software (Jasc PaintShop Pro), and grayscale processing and two-tone processing (threshold: 100) were performed. From the processed image data, the center part was cropped (400 μm × 400 μm), and the area ratio of the black part was read using the histogram as a reference to obtain a binarized value.

[0059] Example 1 First, a cold-rolled foil (60 μm thick) of low-carbon aluminum-killed steel with the chemical composition shown below was prepared as the substrate. The substrate was a press-porous material with through-holes formed by a rolling press, and had multiple rectangular openings with an opening rate of 38.9%. C: 0.04 wt%, Mn: 0.32 wt%, Si: 0.01 wt%, P: 0.012 wt%, S: 0.014 wt%, balance: Fe and unavoidable impurities

[0060] Next, the prepared substrate was subjected to electrolytic degreasing and pickling by immersion in sulfuric acid, and then a 1.0 μm thick undercoat nickel layer was formed under the undercoat nickel plating conditions shown below.

[0061] <Conditions for nickel plating undercoat> Bath composition: Nickel sulfate hexahydrate 250g / L, Nickel chloride hexahydrate 45g / L, Boric acid 30g / L pH 4.0 Bath temperature 60℃ Current density 10A / dm 2

[0062] Next, a roughened nickel layer was formed on the base nickel layer on one side under the following conditions: The roughened nickel layer was formed by carrying out the following particulate nickel formation plating and nickel growth plating.

[0063] <Granular nickel formation plating conditions> Nickel sulfate hexahydrate concentration in plating bath: 10g / L Nickel chloride hexahydrate concentration in plating bath: 10g / L Chloride ion concentration in plating bath: 16.6 g / L Ratio of nickel ions to ammonium ions in the plating bath: nickel ions / ammonium ions (weight ratio) = 0.2 pH: 6.0 Bath temperature: 50℃ Average current density: 21.0A / dm2 Electrolysis time 10 seconds Stirring method: Circulation stirring (stirring flow rate: small) Electrical conductivity of plating bath (bath conductivity): 13.8 S / m (when bath temperature is 50°C and pH is 6.0) In the examples and comparative examples, the stirring flow rate during circulation stirring was described according to the following standards. Large stirring flow rate: For a 2L volume of plating solution, the liquid circulation rate by the pump is 3L / min or more and less than 4L / min During stirring flow rate: For a volume of 2L of plating solution, the liquid circulation rate by the pump is 2L / min or more and less than 3L / min Small stirring flow rate: For a 2L volume of plating solution, the liquid circulation rate by the pump is 1L / min or more and less than 2 / min No stirring: For a 2L volume of plating solution, the liquid circulation rate by the pump is less than 1L / min.

[0064] <Nickel growth plating conditions> Bath composition: Nickel sulfate hexahydrate 250g / L, Nickel chloride hexahydrate 45g / L, Boric acid 30g / L pH: 4.0 Bath temperature: 60℃ Current density: 10A / dm2 Electrolysis time 3.4 seconds

[0065] On the outermost surface of the roughened nickel layer, the ten-point average roughness Rzjis1 of the edge and the ten-point average roughness Rzjis2 of the center were measured. When measuring the ten-point average roughness Rzjis1 of the edge, measurements were taken at both the side and corner parts of the aperture, and the value with the larger difference from the ten-point average roughness Rzjis2 of the center was adopted as Rzjis1 (the bold part in Table 1). Furthermore, because the cross section of the aperture was inclined with respect to the surface of the substrate, the measurement was carried out by moving parallel about 70 μm toward the center from the edge face along the aperture (the boundary between the aperture and the region) observed from above in the Z direction in the laser microscope measurement. On the other hand, when measuring the ten-point average roughness Rzjis2 of the center, the distance (h 103 ) was 1000 μm in the X direction, so measurements were taken by moving parallel about 500 μm toward the center from the edge along the hole (the boundary between the hole and the region) observed from above in the Z direction using a laser microscope. The difference (absolute value) between Rzjis1 and Rzjis2 is shown in Table 1 as ΔRzjis. The values ​​of the developed area ratio Sdr and maximum height Sz are also shown in Table 1. The amount of gas generated and its evaluation are shown in Table 1, and the evaluation of damage to the diaphragm is shown in Table 2.

[0066] <Examples 2 to 10, Comparative Examples 1 and 2> By varying the above plating conditions as shown in Table 3, Rzjis1, Rzjis 2、 Nickel-plated metal materials having different parameters such as Sdr were obtained and evaluated in the same manner as in Example 1. The evaluation of damage to the diaphragm was carried out in Examples 1, 4, and 10 and Comparative Example 4. The results are shown in Tables 1 and 2.

[0067] <Comparative Example 3> The same procedures as in Example 1 were followed up to the nickel base plating, but the particulate nickel formation plating and nickel growth plating were not performed, thereby obtaining a nickel-plated metal material without a roughened nickel layer. The results are shown in Table 1.

[0068] [Table 1]

[0069] [Table 2]

[0070] [Table 3]

[0071] The nickel-plated metal materials obtained in Examples 1 to 10 were confirmed to have a tendency for the presence of a roughened nickel layer to increase the amount of gas generated during alkaline water decomposition. The improvement in gas generation was confirmed more significantly on the cathode side than on the anode side. Furthermore, it was confirmed that by setting ΔRzjis on the surface of the roughened nickel layer to 4.0 μm or less, localized stress concentration on the diaphragm was suppressed. Specifically, in Examples 1 and 4, the number and size of black areas (contact points) were small, and the area ratio of the black areas was significantly low. Although Example 10 had a somewhat large number of black dots, most of the individual black areas were small, so the area ratio of the black areas was also suppressed, and it was determined that damage to the diaphragm could be suppressed. On the other hand, in Comparative Example 1, the number of black dots was also large, and many of the black areas were large, resulting in a high area ratio of the black areas of 1.5 or more, which is considered to have caused significant damage to the diaphragm.

[0072] Example 11 A cold-rolled foil (60 μm thick) of low-carbon aluminum-killed steel similar to that used in Example 1 was prepared as the substrate, except that it did not have a plurality of apertures. A roughened nickel layer was formed under the same conditions as in Example 1 for the base nickel plating and granular nickel formation plating. Growth nickel plating was not performed. The ten-point average roughness Rzjis2, developed area ratio Sdr, and maximum height Sz of the central portion of the obtained nickel-plated metal material were measured, and the amount of gas generated at the cathode and its evaluation are shown in Table 4.

[0073] <Comparative Example 4> A low-carbon aluminum-killed steel sheet (thickness: 0.3 mm) without a plurality of apertures was used as the substrate, and nickel plating was carried out under the same conditions as the nickel base plating conditions in Example 1, except that the electrolysis time was changed to a thickness of 3.0 μm. After nickel plating, the surface roughness was adjusted by transfer from the roll in a temper rolling process. The obtained plated steel sheet was subjected to the same measurements and evaluations as in Example 11. The results are shown in Table 4.

[0074] [Table 4]

[0075] The nickel-plated metal material obtained in Example 11 was able to obtain a current value four times or more larger than that of the nickel-plated steel sheet of Comparative Example 4 without a roughened nickel layer, despite having a ten-point average roughness Rzjis significantly smaller than that of the nickel-plated steel sheet of Comparative Example 4 without a roughened nickel layer, and was therefore excellent in the amount of gas generated. In other words, simply having a high surface roughness, as in Comparative Example 4, did not lead to an increase in the amount of gas generated. On the other hand, Example 11 was able to increase the amount of gas generated by having a roughened nickel layer with an Sdr of 15% or more on the surface. [Industrial Applicability]

[0076] The above-described embodiments and examples can be modified in various ways without departing from the spirit of the present invention. The nickel-plated metal material according to the present disclosure can be suitably used as an electrode for electrolysis or an electrode substrate for electrolysis, and is particularly suitable for use as an electrode for a zero-gap alkaline electrolytic cell. Furthermore, without being limited thereto, the nickel-plated metal material according to the present disclosure can also be used as an electrode for solid polymer electrolysis (PEM type) or high-temperature steam electrolysis (SOFC type). [Explanation of symbols]

[0077] 100: Nickel-plated metal material 20: Base material 50: Roughened nickel layer

Claims

1. a sheet-like metal substrate having a plurality of apertures; a roughened nickel layer provided on at least one surface of the metal substrate; ΔRzjis on the surface on the roughened nickel layer side is 4.0 μm or less, The developed area ratio Sdr on the surface on the roughened nickel layer side is 15.0% or more. Nickel-plated metal material. However, the ΔRzjis is the ten-point average roughness Rzjis of the end of the opening. １ and the ten-point average roughness Rzjis of the central portions of the two adjacent openings. ２ represents the difference between and .

2. The nickel-plated metal material according to claim 1, wherein the developed area ratio Sdr exceeds 50.0%.

3. The ten-point average roughness Rzjis ２ The nickel-plated metal material according to claim 1 or 2, wherein the thickness of the nickel-plated metal material is 1.0 μm or more.

4. 3. The nickel-plated metal material according to claim 1, wherein the maximum height Sz of the surface on the roughened nickel layer side is less than 10 μm.

5. The nickel-plated metal material according to claim 1 or 2, wherein the openings in the metal substrate have an opening rate of 10 to 90%.

6. A sheet-like metal substrate; a roughened nickel layer provided on at least one surface of the metal substrate; Rzjis on the surface on the roughened nickel layer side is 1.0 μm or more and 12.0 μm or less, The developed area ratio Sdr on the surface on the roughened nickel layer side is 15.0% or more. Nickel-plated metal material.

7. The nickel-plated metal material according to claim 1 or 6, wherein the nickel-plated metal material has a thickness of 0.02 mm to 5.02 mm.

8. An electrode substrate for electrolysis, comprising the nickel-plated metal material according to claim 1 or 6.

9. An electrode for electrolysis, comprising the nickel-plated metal material according to claim 1 or 6.

10. An electrolytic cell having an anode, an anode chamber accommodating the anode, a cathode, a cathode chamber accommodating the cathode, and a diaphragm separating the anode chamber and the cathode chamber, 10. An electrolytic cell, wherein at least one of the cathode and the anode comprises the nickel-plated metal material according to claim 1.

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