Nickel-plated metal material, electrode base material for electrolysis, electrode for electrolysis, and electrolytic tank

Abstract

[Problem] 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] This nickel-plated metal material comprises: a sheet-shaped metal base material having a plurality of opening parts; and a roughened nickel layer provided on at least one surface of the metal base material. ΔRzjis on a surface on the roughened nickel layer side is 4.0 μm or less, and a developed area ratio Sdr on the surface on the roughened nickel layer side is 15.0% or more. The ΔRzjis represents the difference between the ten-point average roughness Rzjis1 of the end portion of the opening part and the ten-point average roughness Rzjis2 of the center portion between the two adjacent opening parts.

Description

Nickel-plated metal materials, electrode substrates for electrolysis, electrodes for electrolysis, and electrolytic cells

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

[0002] In recent years, demand for hydrogen produced using renewable energy (so-called green hydrogen) has been increasing. One example of a method for producing green hydrogen is water electrolysis (water electrolysis), which uses power generation from 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. Several types of water electrolysis are known, including alkaline water electrolysis (AWE type), solid polymer electrolysis (PEM type), and high-temperature steam electrolysis (SOEC type). Of these, alkaline water electrolysis has a long-term commercial track record due to its adaptability to large-scale facilities and its low cost of operation compared to other methods.

[0003] In alkaline water electrolytic cells, a "zero gap" design specification (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 is a system in which the diaphragm is sandwiched between a cathode and an 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 forming a LaNi alloy on a nickel substrate. 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－ｚ An electrode is disclosed, characterized in that at the interface between the layers, 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) is 1.5 or more and 3 or less.

[0005] Japanese Patent Application Laid-Open No. 2022-149959

[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, which makes 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.

[0008] In order to solve the above problems, the nickel-plated metal material of this embodiment is characterized in that it 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 on the roughened nickel layer side is 4.0 μm or less, and the developed area ratio Sdr on the surface on the roughened nickel layer side is 15.0% or more, where ΔRzjis is the ten-point average roughness Rzjis of the end of the apertures. １ and the ten-point average roughness Rzjis of the central portions of the two adjacent openings. ２ represents the difference between and .

[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.

[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.

[0011] 2A is a plan view schematically showing one embodiment of a nickel-plated metal material. FIG. 2B is a cross-sectional view schematically showing the A-A' section in FIG. 1. FIG. 2C is an enlarged view of the area surrounded by the dotted line in FIG. 2A. FIG. 2D is a schematic view for explaining the measurement range of the ten-point average roughness in FIG. 2. FIG. 2E is a cross-sectional view schematically showing another embodiment of the nickel-plated metal material. FIG. 2F is a schematic view showing an example of an alkaline water electrolytic cell to which the nickel-plated metal material can be applied. FIG. 2G is a schematic view of an apparatus used to evaluate the amount of gas generated from the nickel-plated metal material of the present embodiment. FIG. 2H is a schematic view showing a pressure-sensitive test method for the nickel-plated metal material.

[0012] First Embodiment A first embodiment for implementing 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 according to the present 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 according to the present 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 , this is not shown. Furthermore, although the roughened nickel layer 50 is shown standing upright in the Z direction in FIGS. 2A and 2C , this is not shown. The nickel-plated metal material 100 according to the present 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] <Substrate 20> As shown in Figures 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 Figure 1, four openings H are regularly arranged in the X direction and two in the Y direction within the substrate 20, but this is not limited to this arrangement. That is, the openings H may be arranged regularly or randomly. Furthermore, the shape of the openings H is not limited to a rectangle, and any known shape, such as a square, ellipse, or perfect circle, can be appropriately selected. In other words, the substrate 20 can be appropriately selected from known lattice plates, meshes, porous materials pressed using a punching press or rotary press, expanded metal, wire mesh, etc. Furthermore, 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 steel plate surface 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 sloped surfaces (not shown), or the cross-section of the openings H may be perpendicular to the surface of the substrate 20 (not shown). An example of the opening width h1, the opening width h20 on the surface side on which the roughened nickel layer 50 described below is formed, and the opening width h10 on the opposite surface side is shown in FIG. 2C . The opening widths h1, h10, and h20 may be approximately equal, or, for example, when the cross-section of the openings H is inclined relative to the surface of the substrate 20, h10 and h20 may be longer than the opening width h1. Furthermore, the opening width of the openings H may be h10<h20 or h10>h20. 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 Figure 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 0.1 mm to 3.0 mm, for example.

[0018] On the other hand, in a region (region B) in the base material 20 where the openings H are not arranged, a roughened nickel layer 50 (described later) is formed. More specifically, region B can be said to be a region surrounded by two adjacent openings H concentrically along the X direction and two adjacent openings H concentrically along the Y direction. The distance h between two adjacent openings H concentrically 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 may be, for example, 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 aggregation 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 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 the base material 20 has openings H as in the present disclosure, if the roughened nickel layer is formed in the 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 ends of the region B (hereinafter also referred to as the ends) near the openings than at the center of the region B (hereinafter also referred to as the center portion).

[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 are different, the parts with higher protrusions may preferentially contact the diaphragm Dp, resulting in stress concentration. Contact with the diaphragm Dp and stress concentration may result in damage to the diaphragm, which may increase the frequency of diaphragm replacement or reduce diaphragm performance. Furthermore, the roughened parts in contact with the diaphragm Dp may fall off, causing problems such as short circuits during water electrolysis or floating in the electrolytic solution as floating matter, potentially reducing the electrolysis efficiency. On the other hand, parts of the roughened nickel layer 50 with lower protrusion heights may create gaps Ga between the diaphragm Dp and the diaphragm Dp, reducing the electrolysis efficiency.

[0022] Based on the above-mentioned trends, the inventors investigated the balance between the effect on the diaphragm and the efficiency of electrolysis, and found that the above-mentioned damage to the diaphragm and the decrease in the efficiency of electrolysis can be suppressed by setting ΔRzjis to a predetermined value or less on the surface of the roughened nickel layer. 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 the efficiency of electrolysis.

[0023] In this disclosure, the above-mentioned ΔRzjis is the ten-point average roughness Rzjis of the edge １ , and the ten-point average roughness Rzjis of the central part ２, and the difference between the surface roughness and the surface roughness. The present disclosure is characterized in that 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 above-mentioned ten-point average roughness Rzjis of the edge １ , the ten-point average roughness Rzjis of the central part ２ 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 Rzjis １ , and Rzjis ２ First, the ten-point average roughness Rzjis of the central part will be explained. ２ is the ten-point average roughness measured at the center of the above-mentioned region B, and is the ten-point average roughness between two adjacent openings H. More specifically, the ten-point average roughness Rzjis ２ is the length h as shown in FIG. １０３ It is measured in a predetermined area (for example, an area of ​​128 μm×128 μm) including the center (midpoint) of the surface roughness. ２ is the length h １０３ and length h １０５ It may be measured in the area including the point where

[0026] Ten-point average roughness Rzjis of the center ２ This can contribute to improving the gas generation area. ２ The preferred value of Rz is 1.0 μm or more, and more preferably 1.2 μm or more. ２ Although there is no particular restriction on the upper limit of Rzjis, it is preferable that Rzjis is 12.0 μm or less in order to satisfy ΔRzjis of 4.0 μm or less. ２On the other hand, when considering high durability over a long period of time, Rzjis is preferably more than 4.5 μm and not more than 12.0 μm, and more preferably more than 4.5 μm and not more than 10.0 μm. ２ is preferably 1.0 μm to 4.5 μm, more preferably 1.2 μm to 4.5 μm.

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

[0028] Furthermore, the ten-point average roughness Rzjis １ In the measurement of the ten-point average roughness Rzjis of the central portion, when the shape of the opening H is rectangular as shown in FIG. 1, the measurement is made at both the side portions and corner portions of the opening H. ２ The value with the larger difference is taken as the ten-point average roughness Rzjis of the edge. １Similarly, even when the shape of the opening H is elliptical, the ten-point mean roughness Rzjis of the central portion of the ten-point mean roughness Rzjis at the end of the major axis radius and the end of the minor axis radius may be ２ The value with the larger difference is taken as the ten-point average roughness Rzjis of the edge. １ In the case where the shape of the opening H is a perfect circle, the average value of the ten-point mean roughness at a plurality of arbitrary points of the opening H may be calculated by multiplying the ten-point mean roughness Rzjis of the end １ It may also be possible to use the following.

[0029] Ten-point average roughness of edge Rzjis １ There is no particular restriction on the numerical range of ΔRzjis as long as it satisfies ΔRzjis and Sdr, but it is preferable that it is 0.1 μm to 15.0 μm in order to satisfy ΔRzjis of 4.0 μm or less.

[0030] The nickel-plated metal material in this embodiment is characterized in that the developed area ratio Sdr on the surface on the roughened nickel layer 50 side is 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, protrusions with a high height may be formed, and therefore a maximum height Sz of less than 23.0 μm is more preferable. 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 be less than 10.0 μm. On the other hand, although there is no particular restriction on the lower limit of the maximum height Sz, it 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 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] As a method for measuring the nickel deposition amount of the roughened nickel layer 50 in this embodiment, for example, the methods described in International Publication No. 2020 / 017655 and International Publication No. 2021 / 020338 can be referred to. That is, the total nickel amount can be determined by measuring the nickel deposition amount of the nickel-plated metal material 100 using ICP (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 a nickel base plating layer 30 (not shown) between the substrate 20 and the roughened nickel layer 50. The nickel base plating layer 30 may be a nickel layer that can be formed on at least one surface of the substrate 20 using, for example, a known Watts bath. The configuration disclosed in WO2021 / 020338 and the like can be applied as appropriate to the nickel base 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 satisfy 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 satisfy 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 the present 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., as described above, 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 Material> The 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 preferably, 18.0 A / dm ２ More preferably, 20.0 A / dm ２ Furthermore, the "granular nickel formation 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 according to this embodiment may include a step of forming a nickel layer by plating nickel on the substrate 20 (hereinafter also referred to as the "base nickel plating step") prior to the 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 to 300 g / L Nickel chloride hexahydrate: 20 to 60 g / L Boric acid: 10 to 50 g / L Bath temperature: 40 to 70°C pH: 3.0 to 5.0 Agitation: air agitation or jet agitation Current density: 5 to 30 A / dm2 In addition to the Watts bath, known nickel sulfamate baths and citric acid baths may also be used for 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 in the roughened nickel plating is small. The method for adjusting the chloride ion concentration, nickel ion to ammonium ion ratio, and bath conductivity of the plating bath to fall within the above ranges is not particularly limited, but an example is a method in which the plating bath contains nickel sulfate hexahydrate, nickel chloride hexahydrate, and ammonium sulfate, and the amounts of these components are appropriately adjusted. An example of plating conditions is as follows:

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

[0046] The addition of ammonia to the nickel plating bath may be carried out using aqueous ammonia or ammonium chloride instead of ammonium sulfate. 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 roughened portion to the desired shape, it is necessary to plate by controlling the bath temperature, average current density, and plating solution circulation rate to appropriate conditions.

[0048] In addition, in the 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 / dm2 from the viewpoint of improving the adhesion between the substrate and the roughened nickel plating layer. ２ Furthermore, for example, by continuously circulating the plating solution at a rate of more than 1 L / min for a plating solution with a volume of 2 L, the growth of the generated plating nuclei can be promoted.

[0049] The amount of nickel deposited in the granular nickel formation plating process is 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 to 350 g / L, nickel chloride hexahydrate 20 to 60 g / L, boric acid 10 to 50 g / L pH 3.0 to 5.0 Bath temperature: 40 to 70°C Current density: 5 to 30 A / dm ２

[0051] The upper limit of the nickel deposition amount in the nickel growth plating step is 7.0 g / m from the viewpoints of adhesion to other members, productivity, and manufacturing costs. ２ Preferably, the amount is 6.0 g / m or less, more preferably 6.0 g / m or less. ２ More preferably, it is 5.0 g / m or less. 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 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 defined as A, and the current density (A / dm ２ ) × electrolysis time (seconds) is B, then "B ≥ 0.0002 × A ２When the value of "-0.0428×A" is controlled to satisfy this, it becomes 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 is provided with a plurality of openings by the above process, it is preferable that the ΔRzjis on the surface of the roughened nickel layer side of the obtained nickel-plated metal material is 4.0 μm or less, and the developed area ratio Sdr on the surface of the roughened nickel layer side is 15.0% or more. However, the ΔRzjis is calculated by multiplying the ten-point average roughness Rzjis of the end １ and the ten-point average roughness Rzjis of the central portion ２ When the metal substrate does not have a plurality of openings, it is preferable that the ten-point average roughness Rzjis on the surface facing the roughened nickel layer be 1.0 μm or more and 12.0 μm or less, and the developed area ratio Sdr on the surface facing the roughened nickel layer be 15.0% or more.

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

[0055] EXAMPLES 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 average roughness (Rzjis), which is a surface texture parameter of the surface of the roughened nickel layer of the nickel-plated metal material, was measured using a laser microscope (Olympus Corporation, 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 obtained analysis image was then subjected to automatic correction processes, such as noise removal and tilt correction, using an analysis application. The ten-point average roughness (Rzjis) was then calculated by line roughness measurement. Note that the analysis was performed without setting any filter conditions (shape removal λf, low-pass filter λs, high-pass filter λc) during analysis. The average value was calculated from 15 measurements performed under the above conditions. In addition, the surface texture parameters of the maximum height Sz and the 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 Values ​​and Evaluation of Gas Generation Amount] Using the apparatus shown in Figures 6A and 6B, the sample was used as the working electrode, a platinum plate as the counter electrode, and Ag / AgCl as the reference electrode. A room-temperature (25°C) KOH (30 wt%) aqueous solution was used as the electrolyte, and a Hokuto Denko Corporation "Multi-Electrochemical Measurement System HZ-Pro" potentiostat was used. The evaluation method employed was linear sweep voltammetry (LSV). Specifically, the sample was first immersed in the electrolyte for 60 minutes to stabilize it in the electrolyte, a common procedure for both evaluating the amount of hydrogen generation and the amount of oxygen generation. Subsequently, when evaluating the amount of hydrogen generation, the potential of the sample immersed in the electrolyte was swept (cathodic polarization) at a constant rate from the potential (natural potential) to -2.0 V, and the change in current value was recorded. The sweep rate was 10 mV / sec, and the current sampling interval was 100 milliseconds. Regarding the amount of hydrogen gas generated, the current value when -1.5 V 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. In addition, when evaluating the amount of oxygen gas generated, the change in current value was recorded using the same procedure as above, except that the potential was swept from the natural potential to +2.0 V (anodic polarization), and the amount of oxygen gas generated was evaluated based on the absolute value of the current value when +0.8 V was applied. Note that the larger the absolute value of the current value, the larger the amount of oxygen gas generated. In addition, as shown in Figure 6B, the measurement diameter of the sample was φ10 mm, and the measurement area was 78.5 mm 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 Diaphragm Damage] A pressure sensitivity 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 FIG. 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 indicating better protection against diaphragm damage. The binarization was performed as follows. First, pressure-sensitive paper image data (640 μm × 480 μm) taken with an optical microscope was imported into graphic software (Jasc PaintShop Pro), and grayscale processing and two-tone processing (threshold: 100) were performed. From the processed image data, the center portion was trimmed (400 μm × 400 μm), and the area ratio of the black portion was read with reference to the histogram to obtain a binarized value.

[0059] Example 1 First, a cold-rolled foil (60 μm thick) of low-carbon aluminum-killed steel having the following chemical composition was prepared as a substrate: The substrate was a press-porous material formed by rolling press to form through-holes, with multiple rectangular openings and 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%, the 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 250 g / L, nickel chloride hexahydrate 45 g / L, boric acid 30 g / L, pH 4.0, bath temperature 60°C, current density 10 A / 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] <Plating conditions for forming granular nickel> Nickel sulfate hexahydrate concentration in plating bath: 10 g / L Nickel chloride hexahydrate concentration in plating bath: 10 g / L Chloride ion concentration in plating bath: 16.6 g / L Ratio of nickel ions to ammonium ions in plating bath: nickel ions / ammonium ions (weight ratio) = 0.2 pH: 6.0 Bath temperature: 50°C Average current density: 21.0 A / dm2 Electrolysis time: 10 seconds Stirring method: circulating stirring (stirring flow rate: small) Electrical conductivity of plating bath (bath conductivity): 13.8 S / m (when bath temperature was 50°C and pH = 6.0) In the examples and comparative examples, the stirring flow rate in circulating stirring was described according to the following standards. High agitation flow rate: For a 2 L volume of plating solution, the liquid circulation rate by the pump is 3 L / min or more and less than 4 L / min. Medium agitation flow rate: For a 2 L volume of plating solution, the liquid circulation rate by the pump is 2 L / min or more and less than 3 L / min. Low agitation flow rate: For a 2 L volume of plating solution, the liquid circulation rate by the pump is 1 L / min or more and less than 2 L / min. No agitation: For a 2 L volume of plating solution, the liquid circulation rate by the pump is less than 1 L / min.

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

[0065] On the outermost surface of the roughened nickel layer, the ten-point average roughness Rzjis of the edge １ , and the ten-point average roughness Rzjis of the central part ２ The ten-point average roughness Rzjis of the edge was measured. １When measuring, the ten-point average roughness Rzjis of the central part is measured at both the side and corner parts of the opening. ２ The value with the larger difference is Rzjis １ (The bold part in Table 1) In addition, since the cross section of the opening portion 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 end face (the boundary between the opening portion and the region portion) along the opening portion observed from above in the Z direction in the laser microscope measurement. On the other hand, the ten-point average roughness Rzjis of the central portion ２ When measuring the distance between two adjacent openings (h １０３ ) was 1000 μm in the X direction, so the measurement was performed by moving parallel about 500 μm toward the center from the end face (boundary between the hole and the region) along the hole observed from above in the Z direction using a laser microscope. １ and Rzjis ２ The difference (absolute value) between these values ​​is shown as ΔRzjis in Table 1. The values ​​of the developed area ratio Sdr and the 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, １ , 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: A nickel-plated metal material without a roughened nickel layer was obtained by performing the same procedures as in Example 1 up to the base nickel plating, but not performing the particulate nickel formation plating or nickel growth plating. The results are shown in Table 1.

[0068]

[0069]

[0070]

[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 rate 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 1.5 or more, which is considered to have caused significant damage to the diaphragm.

[0072] Example 11 A cold-rolled foil (thickness: 60 μm) of low-carbon aluminum-killed steel similar to that of Example 1 was prepared as a 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 the granular nickel plating. Growth nickel plating was not performed. The ten-point average roughness (Rzjis) of the central portion of the obtained nickel-plated metal material was measured. ２ The values ​​of the developed area ratio Sdr and the maximum height Sz were measured, and the amount of gas generated in 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 performed under the same conditions as the nickel undercoat 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]

[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.

[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 (SOEC type).

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

Claims

1. A nickel-plated metal material comprising: 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 the developed area ratio Sdr on the surface facing the roughened nickel layer is 15.0% or more, where ΔRzjis is the ten-point average roughness Rzjis of the edge of the apertures. 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. The nickel-plated metal material according to claim 1 or 2, 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 porosity of the openings in the metal substrate is 10 to 90%.

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

7. The nickel-plated metal material according to claim 1 or 6, wherein the thickness of the nickel-plated metal material is 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 that houses the anode, a cathode, a cathode chamber that houses the cathode, and a diaphragm that separates the anode chamber and the cathode chamber, wherein at least one of the cathode and the anode contains the nickel-plated metal material according to claim 1 or claim 6.

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