Method for manufacturing electrode, and raw material and slurry for electrode used therefor

Abstract

This electrode for a water electrolysis device comprises a base material and Raney nickel supported on the base material. This method for manufacturing an electrode comprises a step for obtaining Raney nickel. The step for obtaining Raney nickel includes an alkali treatment step for eluting aluminum from a NiAl alloy using an alkaline substance. The component composition of the NiAl alloy excluding unavoidable impurities is represented by compositional formula (I).　(I): Al3.00Ni(2.00-(x+y))CuxFey [In composition formula (I), y is a value satisfying 0.00≤y≤0.30; when y is a value satisfying y=0.00, x is a value satisfying 0.00<x<0.30; and when y is a value satisfying 0.00<y≤0.30, x and y are values satisfying 0.00<x+y≤0.45 and 0.00<x≤0.40.]

Description

Method for manufacturing electrodes, and raw materials and slurries for electrodes used therein.

[0001] This disclosure relates to a method for manufacturing electrodes, and to raw materials and slurries for electrodes used therein.

[0002] Water electrolysis is the process of electrolyzing water into hydrogen and oxygen, and is used, for example, as a technology for producing hydrogen. A water electrolysis apparatus includes, for example, an electrolytic cell containing an electrolyte such as alkaline water, and an anode and a cathode arranged in the electrolytic cell with a separator in between. In such a water electrolysis apparatus, alkaline water is electrolyzed by passing an electric current between the anode and the cathode, generating oxygen at the anode and hydrogen at the cathode.

[0003] Patent document 1 (Japanese Patent Publication No. 01-028837) discloses the use of Raney nickel as the anode of a water electrolysis apparatus. Raney nickel is obtained by dissolving aluminum from a NiAl alloy containing nickel and aluminum using an alkaline substance. Numerous pores are formed in Raney nickel due to the dissolution of aluminum.

[0004] Special Publication No. 01-028837

[0005] There is a need for electrodes in water electrolysis devices that exhibit superior water electrolysis performance.

[0006] This disclosure aims to provide a method for manufacturing electrodes having excellent water electrolysis performance in a water electrolysis apparatus, as well as raw materials and slurries for electrodes used therein.

[0007] The method for manufacturing an electrode is a method for manufacturing an electrode for a water electrolysis apparatus, wherein the electrode comprises a substrate and Raney nickel supported on the substrate, the manufacturing method includes a step of obtaining the Raney nickel, the step of obtaining the Raney nickel includes an alkali treatment step of dissolving aluminum from the NiAl alloy with an alkaline substance, and the component composition of the NiAl alloy excluding unavoidable impurities is the following composition formula (I): Al ３．００ Ni(2.00-(x+y))Cu ｘ Fe ｙ(I) [In the compositional formula (I), y is a value satisfying 0.00 ≦ y ≦ 0.30. When y is a value satisfying y = 0.00, x is a value satisfying 0.00 < x < 0.30. When y is a value satisfying 0.00 < y ≦ 0.30, x and y are values satisfying 0.00 < x + y ≦ 0.45 and 0.00 < x ≦ 0.40.] It is represented by.

[0008] The raw material of the electrode is the raw material of the electrode of the water electrolysis device, and includes a base material, a NiAl alloy and Ni metal supported on the base material. The NiAl alloy is the raw material of Raney nickel and elutes aluminum with an alkaline substance. The Ni metal is a metal that may contain Al, the content of Ni in the Ni metal is more than 50% by mass, and the amount of substance of Al contained in the Ni metal is smaller than the amount of substance of Ni. The component composition excluding the inevitable impurities of the NiAl alloy is the following compositional formula (I): Al ３．００ Ni(2.00 - (x + y))Cu ｘ Fe ｙ (I) [In the compositional formula (I), y is a value satisfying 0.00 ≦ y ≦ 0.30. When y is a value satisfying y = 0.00, x is a value satisfying 0.00 < x < 0.30. When y is a value satisfying 0.00 < y ≦ 0.30, x and y are values satisfying 0.00 < x + y ≦ 0.45 and 0.00 < x ≦ 0.40.] It is represented by.

[0009] The slurry is the slurry used for manufacturing the electrode of the water electrolysis device. The slurry includes a powder of NiAl alloy, a powder of Ni metal, and a solvent. The NiAl alloy is the raw material of Raney nickel and elutes aluminum with an alkaline substance. The Ni metal is a metal that may contain Al, the content of Ni in the Ni metal is more than 50% by mass, and the amount of substance of Al contained in the Ni metal is smaller than the amount of substance of Ni. The component composition excluding the inevitable impurities of the NiAl alloy is the following compositional formula (I): Al ３．００ Ni(2.00 - (x + y))Cu ｘ Fe ｙ(I) [In empirical formula (I), y is a value that satisfies 0.00 ≤ y ≤ 0.30, and when y is a value that satisfies y = 0.00, x is a value that satisfies 0.00 < x < 0.30, and when y is a value that satisfies 0.00 < y ≤ 0.30, x and y are values ​​that satisfy 0.00 < x + y ≤ 0.45 and 0.00 < x ≤ 0.40.] This is represented by

[0010] According to the electrode manufacturing method, electrode raw materials, and slurry of this disclosure, an electrode that exhibits excellent water electrolysis performance in a water electrolysis apparatus can be obtained.

[0011] This is a flowchart showing an example of a method for manufacturing an electrode according to the embodiment.

[0012] Embodiments of this disclosure will be described below with reference to the drawings. In this specification, numerical ranges such as "m to n" include upper and lower limits unless otherwise specified, and represent numerical ranges of "m or more and n or less".

[0013] <Method for Manufacturing an Electrode> Figure 1 is a flowchart showing an example of a method for manufacturing an electrode according to this embodiment. The electrode manufactured by the electrode manufacturing method of this embodiment (hereinafter also referred to as "this manufacturing method") is used in a water electrolysis apparatus. The water electrolysis apparatus is preferably an alkaline water electrolysis apparatus.

[0014] This manufacturing method is for manufacturing electrodes for a water electrolysis apparatus, and the electrode comprises a substrate and Raney nickel supported on the substrate. This manufacturing method includes a step of obtaining Raney nickel, and the step of obtaining Raney nickel includes an alkali treatment step of dissolving aluminum from the NiAl alloy with an alkaline substance. In this manufacturing method, the component composition of the NiAl alloy, excluding unavoidable impurities, is represented by the composition formula (I) shown below. Al ３．００ Ni(2.00-(x+y))Cu ｘ Fe ｙ (I) [In empirical formula (I), y is a value that satisfies 0.00 ≤ y ≤ 0.30, and if y is a value that satisfies y = 0.00, then x is a value that satisfies 0.00 < x < 0.30, and if y is a value that satisfies 0.00 < y ≤ 0.30, then x and y are values ​​that satisfy 0.00 < x + y ≤ 0.45 and 0 < x ≤ 0.40.]

[0015] This manufacturing method can include a step of obtaining an electrode. The step of obtaining an electrode may be, for example, a step of obtaining Raney nickel in a state where a NiAl alloy (hereinafter, also referred to as "NiAl alloy (I)") having a component composition excluding inevitable impurities represented by the compositional formula (I) is supported on a substrate, and then obtaining an electrode, or may be a step of obtaining an electrode by supporting Raney nickel obtained from the NiAl alloy (I) on the substrate.

[0016] For example, this manufacturing method may be a method of manufacturing an electrode by: [i] obtaining a NiAl alloy (I); [ii] preparing a slurry containing the NiAl alloy (I); [iii] applying the slurry to a substrate and firing it as necessary to support the NiAl alloy (I) on the substrate; and [iv] subjecting the NiAl alloy (I) supported on the substrate to an alkali treatment or the like to obtain Raney nickel supported on the substrate.

[0017] As described above, the electrode obtained by this manufacturing method contains Raney nickel obtained using the NiAl alloy (I). By using the electrode containing this Raney nickel, an electrode with excellent water electrolysis performance can be obtained in a water electrolysis device. More specifically, in a water electrolysis device, a cathode showing high catalytic activity for hydrogen generation and an anode showing high catalytic activity for oxygen generation can be obtained.

[0018] The electrode obtained by this manufacturing method can be used for either the cathode, which is the hydrogen generation electrode of a water electrolysis device, or the anode, which is the oxygen generation electrode.

[0019] Hereinafter, the substrate and Raney nickel contained in the electrode, the NiAl alloy used in this manufacturing method, and each step of this manufacturing method will be described in detail.

[0020] (Substrate) The substrate of the electrode produced by this manufacturing method is a carrier supporting Raney nickel, and is, for example, a conductor. The substrate preferably contains nickel (Ni) or a Ni alloy. The substrate may be entirely formed of Ni or a Ni alloy, or may have a core layer and a surface layer, where the surface layer is formed of Ni or a Ni alloy and the core layer may be formed of a material other than Ni and Ni alloys. For example, the substrate may have a surface layer coated with Ni or a Ni alloy on a core layer of iron or stainless steel. The substrate is preferably Ni or a Ni alloy, and more preferably Ni.

[0021] The substrate may be a porous substrate or a non-porous substrate. Examples of the porous substrate include punched metal, mesh, foamed metal, and expanded metal. Examples of the non-porous substrate include metal foil and metal plate. The substrate is preferably a porous substrate capable of supporting Raney nickel in the pores.

[0022] (Raney nickel) Raney nickel can be used as a catalyst for the electrodes of a water electrolysis device. Raney nickel is obtained by an alkali treatment that elutes aluminum from a NiAl alloy (I) with an alkali substance. As will be described later, Raney nickel may be a porous body obtained by subjecting a NiAl alloy (I) to an alkali treatment, or may be a porous body with an oxidized surface obtained by subjecting the surface of the porous body to an oxidation treatment.

[0023] (NiAl alloy) The NiAl alloy (I) used in the alkali treatment step of this manufacturing method is an alloy whose component composition excluding inevitable impurities is represented by the above compositional formula (I). The compositional formula (I) means that the molar ratio of aluminum (Al), nickel (Ni), copper (Cu), and iron (Fe) in the entire alloy excluding inevitable impurities is Al:Ni:Cu:Fe = 3.00:(2.00-(x + y)):x:y. The NiAl alloy (I) may or may not contain Fe. The NiAl alloy (I) contains Al ３．００ Ni(2.00-(x + y))Cu ｘ Fe ｙThe alloy may consist of a single phase, or it may consist of multiple phases with different compositions.

[0024] The multiple phases may include, for example, at least a primary phase and further include secondary phases. In this specification, the primary phase of NiAl alloy (I) means a phase that satisfies at least one of the following volume and area conditions.

[0025] Volume Condition: The main phase of NiAl alloy (I) is defined as one phase whose volume ratio exceeds 50% of the total NiAl alloy (I), or two phases whose combined volume ratio (the volume ratio of the phase with the largest volume ratio and the volume ratio of the next largest phase) exceeds 50% of the total NiAl alloy (I). The volume ratio when there is one main phase, and the combined volume ratio when there are two main phases, may be 60% or more, 70% or more, 80% or more, or 90% or more. The volume of each phase constituting NiAl alloy (I) can be calculated, for example, by performing Rietveld analysis on X-ray diffraction (XRD) measurement data of NiAl alloy (I).

[0026] Area Condition: The main phase of NiAl alloy (I) is defined as one phase whose area ratio to the entire cross-section of NiAl alloy (I) exceeds 50%, or two phases whose combined area ratio (the area ratio of the phase with the largest area ratio in any cross-section of NiAl alloy (I) plus the area ratio of the next largest phase) exceeds 50%. Any cross-section of NiAl alloy (I) may be the NiAl alloy (I) observed in the cross-section of the molded body used to calculate the proportion of the area occupied by a specific Al region. The area ratio when there is one main phase, and the total area ratio when there are two main phases, may be 60% or more, 70% or more, 80% or more, or 90% or more. The area of ​​each phase in the cross-section of NiAl alloy (I) can be calculated, for example, by image analysis of elemental mapping data of the cross-section of NiAl alloy (I) obtained by scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX).

[0027] The phases contained in NiAl alloy (I), excluding unavoidable impurities, are Al ４ Ni３ phase, AlNi phase, Al ３ Ni ２ In contrast, Al ３ Ni phase, Al ３ Ni ５ Phase, and AlNi ３ Equivalent Al-Ni base phase; a phase in which some of the Ni in the Al-Ni base phase is replaced with Cu and / or Fe; Al ３ Cu phase, Al ２ Cu phase, AlCu phase, Al ９ Cu １２ In contrast, Al ２ Cu ３ In contrast, Al ４ Cu ９ Phase, and AlCu ３ Equivalent Al-Cu base phase; a phase in which some of the Cu contained in the Al-Cu base phase is replaced with Ni and / or Fe; Al ３ Fe phase, Al ５ Fe ２ In contrast, Al ２ Fe phase, AlFe phase, and AlFe ３ Examples include an equivalent Al-Fe base phase; and a phase in which some of the Fe in the Al-Fe base phase is replaced with Ni and / or Cu. In composition formula (I), when y = 0.00, it is considered that a phase in which some of the Cu in the Al-Cu base phase is replaced with Fe, an Al-Fe base phase, and a phase in which some of the Al-Fe base phase is replaced with Ni and / or Cu will not be formed.

[0028] NiAl alloy (I) may contain one or more of these phases as a main phase or a secondary phase, and may also contain phases that are inevitably formed during manufacturing. For example, NiAl alloy (I) may have Al as the main phase. ３ Ni ２ It may also be an alloy in which the phase is such that the molar ratio of Al, Ni, and Cu in the entire alloy, excluding unavoidable impurities, is Al:Ni:Cu:Fe = 3.00:(2.00-(x+y)):x:y.

[0029] When y in empirical formula (I) is a value that satisfies y = 0.00, empirical formula (I) is represented by empirical formula (I-1) shown below. Al ３．００ Ni(2.00-(x1+y1))Cu ｘ１(I-1) [In the empirical formula (I-1), x1 is a value that satisfies 0.00 < x1 < 0.30.]

[0030] In the composition formula (I-1), x may be in the range of 0.00 < x1 < 0.30, but may also be 0.01 ≤ x1 ≤ 0.29, preferably 0.02 ≤ x1 ≤ 0.28, 0.03 ≤ x1 ≤ 0.27, 0.05 ≤ x1 ≤ 0.25, or 0.07 ≤ x1 ≤ 0.23.

[0031] When y in empirical formula (I) satisfies the value 0.00 < y ≤ 0.30, empirical formula (I) is represented by empirical formula (I-2) shown below. Al ３．００ Ni(2.00-(x2+y2))Cu ｘ２ Fe ｙ２ (I-2) [In the empirical formula (I-2), x² and y² are values ​​that satisfy 0.00 < x² + y² ≤ 0.45, 0.00 < x² ≤ 0.40, and 0.00 < y² ≤ 0.30.]

[0032] In the composition formula (I-2), x² + y² may be in the range of 0.00 < x² + y² ≤ 0.45, but may also be 0.04 ≤ x² + y² ≤ 0.43, preferably 0.05 ≤ x² + y² ≤ 0.42, may also be 0.08 ≤ x² + y² ≤ 0.40, may also be 0.10 ≤ x² + y² ≤ 0.35, may also be 0.12 ≤ x² + y² ≤ 0.32, and may also be 0.15 ≤ x² + y² ≤ 0.30.

[0033] In the composition formula (I-2), x² may be in the range of 0.00 < x² ≤ 0.40, but may also be 0.01 ≤ x² ≤ 0.38, preferably 0.02 ≤ x² ≤ 0.35, 0.03 ≤ x² ≤ 0.30, 0.05 ≤ x² ≤ 0.25, 0.07 ≤ x² ≤ 0.23, or 0.10 ≤ x² ≤ 0.20.

[0034] In the composition formula (I-2), y2 may be in the range of 0.00 < y2 ≤ 0.30, but may also be 0.01 ≤ y2 ≤ 0.29, preferably 0.02 ≤ y2 ≤ 0.28, 0.03 ≤ y2 ≤ 0.25, 0.05 ≤ y2 ≤ 0.23, or 0.07 ≤ y2 ≤ 0.20. In the composition formula (I-2), y2 may be greater than x2, less than x2, or the same as x2.

[0035] In the composition formula (I-2), the ranges of x² and y² can be any combination of the above-mentioned ranges. For example, these combinations may be 0.00 < x² ≤ 0.40 and 0.00 < y² ≤ 0.30, 0.01 ≤ x² ≤ 0.38 and 0.01 ≤ y² ≤ 0.29, 0.02 ≤ x² ≤ 0.35 and 0.02 ≤ y² ≤ 0.28, 0.03 ≤ x² ≤ 0.30 and 0.03 ≤ y² ≤ 0.25, 0.05 ≤ x² ≤ 0.25 and 0.05 ≤ y² ≤ 0.23, 0.07 ≤ x² ≤ 0.23 and 0.07 ≤ y² ≤ 0.20, or 0.10 ≤ x² ≤ 0.20 and 0.07 ≤ y² ≤ 0.20.

[0036] In the composition formula (I-2), the ranges of x² + y², x², and y² can be any combination of the above ranges. For example, this combination is 0.00 < x² + y² ≤ 0.45, 0.00 < x² ≤ 0.40, and 0.00 < y² ≤ 0.30, and may also be 0.04 ≤ x² + y² ≤ 0.43, 0.01 ≤ x² ≤ 0.38, and 0.01 ≤ y² ≤ 0.29, and may also be 0.05 ≤ x² + y² ≤ 0.42, 0.02 ≤ x² ≤ 0.35, and 0.02 ≤ y² ≤ 0.28, and 0.08 ≤ x² + y² ≤ 0.40, 0.03 ≤ It may also be x² ≤ 0.30 and 0.03 ≤ y² ≤ 0.25, and it may also be 0.10 ≤ x² + y² ≤ 0.35, 0.05 ≤ x² ≤ 0.25, and 0.05 ≤ y² ≤ 0.23, and it may also be 0.12 ≤ x² + y² ≤ 0.32, 0.07 ≤ x² ≤ 0.23, and 0.07 ≤ y² ≤ 0.20, and it may also be 0.15 ≤ x² + y² ≤ 0.30, 0.10 ≤ x² ≤ 0.20, and 0.07 ≤ y² ≤ 0.20.

[0037] In the process of obtaining Raney nickel, an alkali treatment step is used to dissolve Al from the NiAl alloy (I). When the amount of Al in the NiAl alloy increases, the amount of Al that can be dissolved increases, resulting in a larger porosity and specific surface area of ​​Raney nickel. Such Raney nickel tends to exhibit excellent catalytic activity, but its strength and durability tend to decrease. When the amount of Al in the NiAl alloy decreases, the porosity and specific surface area of ​​Raney nickel decrease, so catalytic activity tends to decrease, but strength and durability tend to improve. The amount of Al in NiAl alloy (I) is greater than the amount of Ni and Cu in NiAl alloy (I) in terms of molars, and the content of Al, Ni, and Cu are in the relationship shown in compositional formula (I). Therefore, Raney nickel obtained using NiAl alloy (I) has an appropriate porosity and specific surface area, so it can exhibit good catalytic activity while also having good durability.

[0038] Raney nickel obtained using NiAl alloy (I) exhibits superior catalytic activity compared to Raney nickel obtained using Cu-free NiAl alloy or Cu and Fe-free NiAl alloy. Therefore, electrodes obtained by this manufacturing method can be used to obtain electrodes for water electrolysis devices that exhibit excellent water electrolysis performance. Fe contained in Raney nickel can improve the catalytic activity of Raney nickel with a small amount compared to Cu, so in compositional formula (I), if y > 0.00, y may be smaller than x.

[0039] The Raney nickel contained in the electrodes obtained by this manufacturing method is thought to exhibit catalytic activity by generating complex (acid) hydroxides during the operation of the water electrolysis apparatus. Complex (acid) hydroxides refer to a compound of at least two (acid) hydroxides from among Ni(O)OH, Fe(O)OH, Cu(O)OH, and Al(O)OH. In compositional formula (I), when y = 0.00, it is considered that the complex (acid) hydroxide is a compound of at least two (acid) hydroxides from among Ni(O)OH, Cu(O)OH, and Al(O)OH. When x in compositional formula (I) is greater than 0.00, the electrodes obtained by this manufacturing method tend to generate complex (acid) hydroxides that exhibit high activity during the operation of the water electrolysis apparatus, and thus tend to exhibit high catalytic activity. When x in compositional formula (I) is 0.40 or less and y is 0.30 or less, the electrodes obtained by this manufacturing method can suppress the elution of iron ions and copper ions into the electrolyte when used in a water electrolysis apparatus. Iron and copper ions dissolved in the electrolyte can cause increased resistance due to separator clogging, and can also cause internal short circuits by precipitation as metals or compounds on the electrode surface. Electrodes produced by this manufacturing method are less prone to increased resistance and internal short circuits in water electrolysis devices.

[0040] NiAl alloy (I) typically contains unavoidable impurities. These unavoidable impurities are those originating from the raw materials of NiAl alloy (I) or those inevitably introduced during the manufacturing process. Examples of unavoidable impurities include elements other than those mentioned above (Al, Ni, Cu, and Fe) contained in NiAl alloy (I), such as one or more selected from the group consisting of magnesium (Mg), silicon (Si), titanium (Ti), chromium (Cr), manganese (Mn), cobalt (Co), zinc (Zn), tin (Sn), and lead (Pb). The amount of unavoidable impurities contained in NiAl alloy (I) does not need to affect the catalytic properties of the Raney nickel obtained from NiAl alloy (I).

[0041] The method for producing NiAl alloy (I) is not particularly limited and can be produced by known alloy manufacturing methods such as casting, rapid solidification, mechanical alloying, and sputtering.

[0042] (Process for obtaining Raney nickel) The process for obtaining Raney nickel includes the alkali treatment process described above (Figure 1). This alkali treatment process causes Al, a component soluble in alkaline substances, to leach from the NiAl alloy (I). Therefore, this manufacturing method makes it possible to produce Raney nickel having a porous structure with a large specific surface area formed by numerous pores.

[0043] The process for obtaining Raney nickel may further include an oxidation step in which the surface of the porous body obtained by the alkali treatment step is oxidized (Figure 1). The process for obtaining Raney nickel may or may not include the oxidation step, as long as it includes the alkali treatment step.

[0044] (Alkali treatment process) The alkali treatment process is carried out by bringing the NiAl alloy (I) into contact with an alkaline substance. When the NiAl alloy (I) comes into contact with the alkaline substance, the NiAl alloy (I) and the alkaline substance react, and the Al in the NiAl alloy (I) dissolves to obtain a porous body. This porous body may be used as Raney nickel. The alkali treatment process may dissolve all the Al contained in the NiAl alloy (I), but if a porous body can be formed, some of the NiAl alloy may remain without dissolving.

[0045] Examples of alkaline substances include solutions of alkali metal compounds, preferably aqueous solutions of alkali metal compounds. Examples of alkali metal compounds include alkali metal hydroxides and alkali metal salts. Examples of alkali metal hydroxides include sodium hydroxide, potassium hydroxide, and lithium hydroxide. Examples of alkali metal salts include sodium carbonate, potassium carbonate, and lithium carbonate. The alkaline substance is preferably an alkali metal hydroxide.

[0046] The method for eluting Al from NiAl alloy (I) is not particularly limited as long as the NiAl alloy (I) and the alkaline substance are brought into contact so that the NiAl alloy (I) reacts with the alkaline substance. If the alkaline substance is a solution, the NiAl alloy (I) and the alkaline substance may be brought into contact by spraying the alkaline substance onto the NiAl alloy (I) or by immersing the NiAl alloy (I) in the alkaline substance. If the NiAl alloy (I) is in powder form, the NiAl alloy (I) and the alkaline substance may be brought into contact by adding it to a solution of the alkaline substance and stirring.

[0047] The shape and form of the NiAl alloy (I) in contact with the alkaline substance are not particularly limited. The NiAl alloy (I) may be, for example, a powder, or it may be NiAl alloy (I) supported on a first substrate (base material) that serves as the base material for the electrode. The first substrate only needs to support at least NiAl alloy (I), and may also support components other than NiAl alloy (I) together with NiAl alloy (I) (hereinafter, the components such as NiAl alloy supported on the first substrate will be collectively referred to as "supported components").

[0048] The average particle size of the powdered NiAl alloy (I) is, for example, 1 to 150 μm, but may also be 5 to 100 μm or 5 to 50 μm. The average particle size of NiAl alloy (I) refers to the particle size at 50% of the cumulative value in the particle size distribution determined by laser diffraction and scattering.

[0049] The first substrate supporting the NiAl alloy (I) is, for example, a conductor. The first substrate may also be a material that constitutes part of the electrodes of a water electrolysis device. Examples of materials that form the first substrate include the materials described above for use in the substrate. As described above for the substrate, the first substrate may be a porous substrate or a non-porous substrate, and examples of their shapes and structures include the shapes and structures described above for the substrate. Preferably, the first substrate is a porous substrate that can support the supporting component to be supported on the first substrate within its pores.

[0050] The method for supporting the supporting component on the first substrate is not particularly limited. For example, NiAl alloy (I) may be supported on the first substrate by thermal spraying. Plasma spraying is one example of a thermal spraying method. Alternatively, the process for obtaining Raney nickel may further include a step of applying a first slurry containing NiAl alloy (I) and a first solvent to the first substrate, and this application step may cause the supporting component such as NiAl alloy (I) to be supported on the first substrate. Examples of the first solvent include water, N-methyl-2-pyrrolidone (NMP), and N-ethyl-2-pyrrolidone (NEP).

[0051] The first slurry may be applied using a known coating device such as a die coater, roll coater, knife coater, blade coater, bar coater, spray coater, or screen printing device, or it may be applied by immersing the first substrate in the first slurry. The first slurry may be applied to the entire surface of the first substrate, or to a part of the surface of the first substrate. If the first substrate is in the form of a plate, the first slurry may be applied to one or both sides of the first substrate. If the first substrate is a porous substrate, the first slurry may be impregnated into the pores of the first substrate by pressing the first substrate to which the first slurry has been applied. If the first substrate is a porous substrate, any first slurry that has not impregnated into the pores and remains on the surface of the first substrate may be scraped off using a spatula or the like.

[0052] The process for obtaining Raney nickel may further include a step of drying and calcining the first slurry applied to the first substrate. In this case, the alkali treatment step is preferably carried out after the calcination step. For example, the first substrate supporting the supported component may be obtained by applying the first slurry to the first substrate and drying it, or by calcining after application and drying. The drying of the first slurry applied to the first substrate can be carried out using known drying equipment such as a hot air drying oven, an infrared drying oven, and a hot plate. The drying temperature may be, for example, 40 to 120°C, or 50 to 100°C. The drying time may be, for example, 1 to 300 minutes, or 30 to 200 minutes. After drying the first slurry, the first substrate to which the first slurry has been applied may be pressed.

[0053] The first slurry, applied to the first substrate and dried, may be fired. This firing helps to suppress unevenness in the thickness of the first substrate supporting the supported component, and if the first substrate is a porous substrate, it facilitates uniform penetration of the supported component into the first substrate. If the supported component contains Ni metal, as described later, firing facilitates bonding between NiAl alloy (I) particles and / or between NiAl alloy (I) particles and the first substrate.

[0054] If the first substrate has a supported component, the alkali treatment step only requires eluting Al from the NiAl alloy (I) contained in the supported component on the first substrate. As described above, if the step of obtaining Raney nickel includes a step of thermal spraying NiAl alloy (I) onto the first substrate, or if the step of obtaining Raney nickel includes a step of applying the first slurry to the first substrate, the NiAl alloy (I) treated in the alkali treatment step may be supported on the first substrate. The supported component supported on the first substrate may be a calcined product obtained by calcining the first slurry described above. In the alkali treatment step, for example, Al can be eluted from the NiAl alloy (I) by immersing the entire first substrate supporting the supported component in an alkaline solution. This makes it possible to obtain a first substrate with a porous body supported.

[0055] The NiAl alloy (I) contained in the first slurry is preferably in powder form. The average particle size of the powdered NiAl alloy (I) can be within the range described above.

[0056] The first slurry may further contain Ni metal. The Ni metal is a metal that may contain Al, where the Ni content of the Ni metal is more than 50% by mass, and the amount of Al contained in the Ni metal is less than the amount of Ni contained in the Ni metal. The Ni content in the Ni metal may be 60% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, or 98% by mass or more. The Ni metal may contain Al within the above-mentioned range of amounts, but may not contain Al. The metal content contained in the Ni metal can be determined, for example, by scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX).

[0057] Ni metal can function as a binder that binds NiAl alloy (I) particles together, and / or NiAl alloy (I) particles together with the first substrate, by firing the first substrate coated with the first slurry. As a result, Raney nickel particles together, and / or Raney nickel particles together with the first substrate, can be well bound.

[0058] The Ni metal may contain metals other than Ni, for example, one or more selected from the group consisting of Al, Cu, Mg, Si, Ti, Cr, Mn, Co, Zn, Sn, Pb, Fe, Ag, Pt, and Au. When the Ni metal contains metals other than Ni, the Ni metal is an alloy other than the NiAl alloy (I) described above, and more specifically, an alloy in which the amount of Al contained in the Ni metal is less than the amount of Ni contained in the Ni metal. The Ni metal may be Raney nickel, for example, Raney nickel obtained in the process for obtaining Raney nickel described herein.

[0059] It is preferable that the ratio of the amount of substance (moles) of Ni to the total amount of substance (moles) of all elements contained in the Ni metal [mol%] is greater than the ratio of the amount of substance (moles) of Ni to the total amount of substance (moles) of all elements contained in the NiAl alloy (I) [mol%]. Furthermore, it is preferable that the ratio of the total amount of substance (total moles) of metals other than Ni to the total amount of substance (moles) of all elements contained in the Ni metal [mol%] is less than the ratio of the total amount of substance (total moles) of Cu and Fe to the total amount of substance (moles) of all elements contained in the NiAl alloy (I) [mol%]. As described above, when the first slurry is fired, Al, Cu, and Fe diffuse from the NiAl alloy (I) to the Ni metal at the contact area between the NiAl alloy (I) and the Ni metal due to the thermal energy from firing and the elemental concentration gradient. This makes it easier for the NiAl alloy (I) and the Ni metal to bond. When NiAl alloy (I) and Ni metal bond together, strong electron conduction paths are more easily formed, making it easier to obtain electrodes with excellent water electrolysis performance in water electrolysis devices.

[0060] Ni metal is preferably in powder form. The average particle size of the Ni metal is, for example, 1 to 10 μm, but may also be 1 to 8 μm or 2 to 5 μm. The average particle size of the Ni metal refers to the value measured by the Fischer method.

[0061] When the NiAl alloy (I) and Ni metal contained in the first slurry are in powder form, it is preferable that the average particle size of the NiAl alloy (I) is larger than the average particle size of the Ni metal. This makes it easier for the Ni metal to penetrate the gaps in the NiAl alloy, allowing the Ni metal to function more effectively as a binder.

[0062] The Ni metal content in the first slurry may be 15 to 95% by mass, 20 to 90% by mass, or 25 to 85% by mass, relative to the total amount of NiAl alloy (I) and Ni metal. The solvent content in the first slurry may be 15 to 70% by mass, 20 to 60% by mass, 25 to 55% by mass, or 27 to 50% by mass, relative to the total amount of the first slurry.

[0063] The first slurry may further contain components other than NiAl alloy (I), the first solvent, and Ni metal. For example, the first slurry may contain a thickening agent to adjust the viscosity of the first slurry. Examples of thickening agents include carboxymethylcellulose (CMC), polytetrafluoroethylene (PTFE), and polyvinylidene fluoride (PVdF).

[0064] The treatment temperature for the alkali treatment step is preferably 90 to 150°C, but may also be 95 to 145°C or 100 to 140°C. If the alkaline substance is a solution, the alkali treatment step may be carried out while the temperature of the solution is adjusted and maintained within the above range. For example, NiAl alloy (I) may be added to an alkaline substance in solution, and then the alkali treatment step may be carried out after heating to the above treatment temperature.

[0065] The processing time for the alkali treatment step is, for example, 60 to 360 minutes, but may also be 100 to 300 minutes or 120 to 240 minutes.

[0066] The amount of alkali substance used in the alkali treatment process should be set according to the amount of Al contained in the NiAl alloy (I). The amount of alkali substance may be less than the stoichiometric amount of Al contained in the NiAl alloy (I), may be the same amount, or may be in excess. The mass ratio of NiAl alloy (I): alkali substance in solution in the alkali treatment process (NiAl alloy (I): alkali substance in solution) may be, for example, 1:10 to 1:500, 1:50 to 1:450, or 1:100 to 1:400.

[0067] When the alkaline substance is a solution of an alkali metal compound, the concentration of the solution may be, for example, 1 to 20 mol / L, 2 to 18 mol / L, or 3 to 15 mol / L.

[0068] The above-mentioned conditions in the alkali treatment process can be combined in any way. For example, if the treatment temperature in the alkali treatment process is 100°C or higher, the concentration of the alkali metal compound solution may be 3 mol / L or higher, and if the treatment temperature in the alkali treatment process is 140°C or higher, the concentration of the alkali metal compound solution may be 14 mol / L or higher. In the alkali treatment process, it is preferable to raise the treatment temperature as the concentration of the alkali metal compound solution increases.

[0069] The alkali treatment process is preferably carried out under atmospheric pressure (10¹³ hPa). This allows for easier removal of hydrogen generated during the alkali treatment process compared to carrying out the process under pressure, thus preventing the need for complex hydrogen removal equipment.

[0070] The porous material obtained through the alkaline treatment process may be washed as needed. Washing can be done with water. If powdered NiAl alloy (I) is immersed in an alkaline solution, the porous material may be recovered by solid-liquid separation such as filtration.

[0071] (Oxidation Process) The oxidation process is a process of oxidizing the surface of the porous material obtained by the alkali treatment process, in which Al is dissolved from the NiAl alloy (I) with an alkaline substance. The surface of the porous material obtained by the alkali treatment process is highly reactive with oxygen and may spontaneously ignite in air, making it difficult to handle during storage, etc. By carrying out the oxidation process to oxidize the surface of the porous material, the reactivity of the porous material with oxygen can be reduced, thereby improving the ease of handling during storage, etc. If part or all of the surface of the porous material is not oxidized, the porous material may be stored in a solvent or the like to suppress contact with air.

[0072] The oxidation process is carried out by bringing the porous material into contact with an acidic substance. When the acidic substance comes into contact with the surface of the porous material, the surface of the porous material is oxidized. The porous material with an oxidized surface may be used as Raney nickel. The oxidation process only needs to oxidize at least a portion of the surface of the porous material, but it is preferable to oxidize the entire surface of the porous material.

[0073] Examples of acidic substances include acidic solutions. Examples of acidic solutions include aqueous solutions of hydrogen peroxide, sodium peroxide, sodium percarbonate, and sodium perborate, with aqueous hydrogen peroxide being preferred.

[0074] The shape and form of the porous body that comes into contact with the acidic substance are not particularly limited. The porous body may be, for example, a powdered porous body, or a porous body supported on a first substrate. The porous body supported on the first substrate may be obtained by treating the first substrate supporting the supporting component in an alkali treatment step. The porous body supported on the first substrate may be supported on the first substrate in a state mixed with components other than the porous body or their raw materials.

[0075] The method for bringing a porous material into contact with an acidic substance is not particularly limited as long as the surface of the porous material is oxidized. If the acidic substance is an acidic solution, the porous material may be brought into contact with the acidic substance by spraying the acidic solution onto the porous material; or by immersing a powdered porous material or a porous material supported on a first substrate in an acidic solution. If the porous material is in powder form, the porous material may be brought into contact with the acidic substance by adding it to an acidic solution and stirring.

[0076] The processing temperature for the oxidation process is, for example, 10 to 80°C, but may also be 15 to 70°C or 15 to 60°C. The processing time for the oxidation process is, for example, 5 to 720 minutes, but may also be 60 to 700 minutes or 120 to 650 minutes. When an acidic solution is used as the acidic substance, the concentration of the acidic solution is, for example, 0.1 to 10.0 mol / L or 0.3 to 8.0 mol / L. The mass ratio of the porous material to the acidic solution (porous material: acidic solution) in the oxidation process is, for example, 1:5 to 1:100, but may also be 1:7 to 1:80 or 1:9 to 1:50.

[0077] The Raney nickel obtained through the oxidation process may be washed if necessary. Washing can be done with water. If the powdered porous material is immersed in an acidic solution, the Raney nickel may be recovered by solid-liquid separation such as filtration.

[0078] (Step to obtain electrodes) The step to obtain electrodes may be to carry out the step to obtain Raney nickel while NiAl alloy (I) is supported on a first substrate, or it may be a step to obtain electrodes by supporting the Raney nickel obtained from NiAl alloy (I) on a substrate (hereinafter also referred to as the "second substrate").

[0079] Methods for supporting NiAl alloy (I) on a first substrate, and for performing an alkali treatment step and an oxidation step while NiAl alloy (I) is supported on the first substrate, include the methods described above. This makes it possible to obtain an electrode in which Raney nickel is supported on the first substrate. From the viewpoint of making it difficult for Raney nickel to fall off the first substrate, the method of supporting NiAl alloy (I) on the first substrate is preferably one using the first slurry described above, and preferably includes a step of applying the first slurry to the first substrate.

[0080] When obtaining an electrode by supporting Raney nickel on a second substrate, it is preferable to perform an alkali treatment step and, if necessary, an oxidation step on the NiAl alloy (I) that is not supported on a substrate such as the first substrate to obtain Raney nickel.

[0081] The second substrate is, for example, a conductor and can be formed from a carbon material, a metal material, or a polymer electrolyte. The second substrate may be a porous substrate or a non-porous substrate. The second substrate may be one of those described in the description of the first substrate.

[0082] One method for supporting Raney nickel on a second substrate is to coat the second substrate with a second slurry containing Raney nickel and a second solvent. Examples of the second solvent include water; alcohols such as methanol, ethanol, and propanol; and mixed solvents of water and alcohol.

[0083] The second slurry may contain components other than Raney nickel and the second solvent. Examples of such components include conductive porous carbon, ionomers, and conductive oxides. Examples of porous carbon include carbon black such as Ketjenblack and acetylene black, activated carbon, graphite, and carbon nanotubes. Examples of ionomers include fluorine-based resins such as perfluorocarbon sulfonic acid polymers. Examples of conductive oxides include niobium-substituted titanium dioxide.

[0084] The second slurry can be applied by the method described for the application of the first slurry. The second slurry may be applied to the entire surface of the second substrate, or to a portion of the surface of the second substrate. If the second substrate is in the form of a plate, the second slurry may be applied to one or both sides of the second substrate. If the second substrate is a porous substrate, the second slurry may be impregnated into the pores of the second substrate by pressing the second substrate to which the second slurry has been applied. If the second substrate is a porous substrate, any second slurry that has not impregnated into the pores and remains on the surface of the second substrate may be scraped off using a spatula or the like.

[0085] After applying the second slurry to the second substrate, the second slurry may be dried. The drying of the second slurry can be carried out, for example, using the apparatus, temperature, and time described for drying the first slurry. After drying the second slurry, the second substrate coated with the second slurry may be pressed.

[0086] <Electrode Raw Materials> The electrode raw materials of this embodiment are used in the manufacture of electrodes for a water electrolysis apparatus. The electrode raw materials include a first substrate (base material), and NiAl alloy (I) and Ni metal supported on the first substrate. NiAl alloy (I) is a raw material for Raney nickel and dissolves aluminum with an alkaline substance. The Ni metal is a metal that may contain Al, the Ni content of the Ni metal is more than 50% by mass, and the amount of Al contained in the Ni metal is less than the amount of Ni.

[0087] Since the electrode raw materials can be used in the manufacture of electrodes for water electrolysis devices, it is possible to obtain a cathode that exhibits good catalytic activity for hydrogen generation and an anode that exhibits good catalytic activity for oxygen generation in a water electrolysis device.

[0088] Examples of the first substrate, NiAl alloy (I), and Ni metal include those described above. NiAl alloy (I) can be manufactured by the manufacturing method described above. Examples of alkaline substances and methods for eluting Al from NiAl alloy (I) using alkaline substances include those described above. Examples of methods for obtaining Raney nickel from NiAl alloy (I) include those described above.

[0089] As a method for supporting the NiAl alloy (I) and Ni metal on the first substrate, the method described above can be used, but it is preferable to apply a slurry containing the NiAl alloy (I) and Ni metal to the first substrate. The slurry may be the first slurry described above.

[0090] The NiAl alloy (I) and Ni metal supported by the first substrate may be in powder form. The average particle size of the powdered NiAl alloy (I) and Ni metal may be within the range described above. The first substrate may also contain other components besides the NiAl alloy (I) and Ni metal. Examples of other components include the thickeners described above.

[0091] <Slurry> The slurry of this embodiment is a slurry used in the manufacture of electrodes for a water electrolysis apparatus (hereinafter also referred to as "this slurry"). This slurry contains NiAl alloy (I) powder, Ni metal powder, and a solvent. NiAl alloy (I) is a raw material for Raney nickel and dissolves aluminum with an alkaline substance. Ni metal is a metal that may contain Al, wherein the Ni content of the Ni metal is more than 50% by mass, and the amount of Al contained in the Ni metal is less than the amount of Ni.

[0092] This slurry can be used to manufacture electrodes for a water electrolysis apparatus, thereby enabling the production of a cathode that exhibits good catalytic activity for hydrogen generation and an anode that exhibits good catalytic activity for oxygen generation in a water electrolysis apparatus. This slurry may also be the first slurry described above.

[0093] Examples of NiAl alloys include those listed above. The average particle size range of the NiAl alloy powder is within the range listed above. NiAl alloys can be manufactured by the manufacturing method described above. The process for obtaining Raney nickel may be the process described above, and may include the alkali treatment process described above, and may also include the oxidation process described above if necessary. Examples of alkali substances and methods for dissolving Al from NiAl alloys with alkali substances include the alkali substances and methods described above.

[0094] Examples of Ni metals include those listed above. The average particle size range of the Ni metal powder is within the range described above. Examples of solvents include those described in the first solvent section above.

[0095] This slurry may contain other components besides NiAl alloy powder, Ni metal powder, and solvent. Examples of other components include the thickening agents mentioned above.

[0096] The present disclosure will be explained in more detail below with reference to test examples. [Test Examples 1-21] (Preparation of NiAl alloy) Aluminum, nickel, copper (if present), and iron (if present) were mixed to obtain a mixture with the compositional formulas shown in Tables 1 and 2. This mixture was heated and melted at 1600°C using a high-frequency induction melting furnace, and then cooled to obtain an alloy ingot of NiAl alloy represented by the compositional formulas shown in Tables 1 and 2. By crushing the obtained alloy ingot, a powder of NiAl alloy with the above composition was obtained. The average particle size of the obtained powder was measured by laser diffraction and scattering methods and was in the range of 40 to 60 μm in all cases.

[0097] (Preparation of electrode raw materials) Next, NiAl alloy powder (2 g) was immersed in a 14M sodium hydroxide aqueous solution (30 g) and subjected to alkaline treatment at 140°C for 3 hours (alkaline treatment step). Subsequently, a porous body was obtained from which aluminum had leached out of the NiAl alloy by filtration and washing with water.

[0098] A porous material powder (1.5 g) was immersed in a 5% by mass hydrogen peroxide aqueous solution (14 g) and subjected to oxidation treatment at 20°C for 10 hours (oxidation step). Subsequently, by filtration and washing with water, a Raney nickel powder with an oxidized porous material surface was obtained.

[0099] (Electrode preparation) A slurry was prepared by dispersing Raney nickel powder, Ketjenblack, and a 20% Nafion® dispersion (DE2020CS type: manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) in a mixed solvent of water and ethanol. An electrode was obtained by coating the prepared slurry onto a glassy carbon substrate (second substrate), and this was used as the working electrode.

[0100] [Evaluation of catalytic activity for hydrogen generation] The working electrodes obtained in Test Examples 1 to 8 were used in a three-electrochemical measuring device to evaluate the hydrogen generation activity of Raney nickel powder.

[0101] The working electrode and the platinum coil (counter electrode) were immersed in a 7 mol / L potassium hydroxide solution as the electrolyte. A mercury-mercury oxide electrode was used as the reference electrode and connected to the electrolyte via a liquid junction. The potential of the working electrode was swept at 10 mV / s relative to the reference electrode, and the hydrogen generation current relative to the electrode potential was 10 mA / cm². ２ The overpotential [mV] was measured under these conditions. The results are shown in Table 1. A smaller overpotential indicates better catalytic activity for hydrogen generation.

[0102]

[0103] [Evaluation of catalytic activity for oxygen evolution] The working electrodes obtained in Test Examples 9 to 21 were used in a three-electrochemical measuring device to evaluate the oxygen evolution activity of Raney nickel powder.

[0104] The working electrode and the platinum coil (counter electrode) obtained above were immersed in a 7 mol / L potassium hydroxide solution as the electrolyte. A mercury-mercury oxide electrode was used as the reference electrode and connected to the electrolyte via a liquid junction. The potential of the working electrode was swept at 10 mV / s relative to the reference electrode, and the current value [mA / cm²] when the electrode potential was 1.7 V (vs. reversible hydrogen electrode) was measured. ２ The following was measured. The results are shown in Table 2. A higher current value indicates better catalytic activity for oxygen evolution.

[0105]

[0106] [Test Examples 22 and 23] (Preparation of NiAl Alloy) Aluminum, nickel, copper (if present), and iron were mixed to obtain a mixture with the compositional formula shown in Table 3. This mixture was heated and melted at 1600°C using a high-frequency induction melting furnace, and then cooled to obtain an alloy ingot of NiAl alloy represented by the compositional formula shown in Table 3. By crushing the obtained alloy ingot, a powder of NiAl alloy with the above composition was obtained. The average particle size of the obtained powder was measured by laser diffraction and scattering methods and was in the range of 40 to 60 μm in all cases.

[0107] (Preparation of materials to be used) NiAl alloy powder: NiAl alloy powder prepared as described above Ni metal powder: Ni nickel "NIE10PB" (average particle size: 2-3 μm) (manufactured by Kojun Chemical Laboratory Co., Ltd.) Thickener: CMC "Selogen EP" (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) First solvent: Water First base material: Ni metal porous material "Cellmet (registered trademark) #8" (50 mm long, 50 mm wide, 1.2 mm thick) (manufactured by Sumitomo Electric Industries, Ltd.)

[0108] (Preparation of the first slurry) The first slurry was prepared by mixing NiAl alloy powder, Ni metal powder, a thickener, and the first solvent. The amounts of NiAl alloy powder and Ni metal powder were adjusted so that the content of Ni metal powder in the first slurry was 78% by mass relative to the total amount of NiAl alloy powder and Ni metal powder.

[0109] (Electrode Preparation) The first slurry was applied to both sides of the first substrate, and the first slurry that remained on the surface without being impregnated into the pores of the first substrate was scraped off with a spatula. The first slurry applied to the first substrate was dried at 80°C for 60 minutes, pressed, and then fired at 700°C for 2 hours to obtain the first substrate supporting the fired body. The fired body and the first substrate were immersed in a 14 mol / L sodium hydroxide aqueous solution at 130°C for 4 hours (alkali treatment step), washed with water, and obtained the first substrate supporting the porous body. The first substrate supporting the porous body was immersed in a hydrogen peroxide aqueous solution to oxidize the surface of the porous body (oxidation step), washed with water, and obtained an electrode, which was used as the working electrode.

[0110] [Evaluation of catalytic activity for oxygen evolution] The working electrode obtained in Test Example 22 or 23 and a nickel mesh as the counter electrode were immersed in a 7 mol / L potassium hydroxide solution as the electrolyte. A mercury-mercury oxide electrode was used as the reference electrode and connected to the electrolyte via a liquid junction. The working electrode potential was held at 1.5 V (vs. reversible hydrogen electrode) for 1 minute, and then the working electrode potential was held at 0.0 V (vs. reversible hydrogen electrode) for 1 minute. This cycle was repeated 1500 times. After that, the potential of the working electrode (vs. reversible hydrogen electrode) was swept at 1 mV / s relative to the reference electrode, and the current value was read when it reached 1.49 V (vs. reversible hydrogen electrode). The results are shown in Table 3. The larger the current value shown in Table 3, the better the catalytic activity for oxygen evolution in water electrolysis.

[0111]

[0112] [Note] The exemplary embodiments described above will be understood by those skilled in the art to be specific examples of the following embodiments. (Embodiment 1) A method for manufacturing an electrode for a water electrolysis apparatus, wherein the electrode comprises a substrate and Raney nickel supported on the substrate, the manufacturing method includes a step of obtaining the Raney nickel, the step of obtaining the Raney nickel includes an alkali treatment step of dissolving aluminum from the NiAl alloy with an alkaline substance, and the component composition of the NiAl alloy excluding unavoidable impurities is the following composition formula (I): Al ３．００ Ni(2.00-(x+y))Cu ｘ Fe ｙ(I) A method for manufacturing an electrode represented by the composition formula (I), where y is a value that satisfies 0.00 ≤ y ≤ 0.30, and when y is a value that satisfies y = 0.00, x is a value that satisfies 0.00 < x < 0.30, and when y is a value that satisfies 0.00 < y ≤ 0.30, x and y are values ​​that satisfy 0.00 < x + y ≤ 0.45 and 0.00 < x ≤ 0.40. (Aspect 2) The method for manufacturing an electrode according to aspect 1, wherein x and y in composition formula (I) are values ​​that satisfy 0.02 ≤ x < 0.28 and y = 0.00. (Aspect 3) The method for manufacturing an electrode according to aspect 1, wherein x and y in composition formula (I) are values ​​that satisfy 0.05 ≤ x + y ≤ 0.42, 0.00 < x ≤ 0.40, and 0.00 < y ≤ 0.30. (Aspect 4) The method for manufacturing an electrode according to aspect 1 or 3, wherein in the composition formula (I), x and y are values ​​that satisfy 0.02 ≤ x ≤ 0.35 and 0.02 ≤ y ≤ 0.28. (Aspect 5) The method for manufacturing an electrode according to any one of aspects 1 to 4, wherein the step of obtaining the Raney nickel further includes an oxidation step of oxidizing the surface of the porous body obtained by the alkali treatment step. (Aspect 6) The method for manufacturing an electrode according to any one of aspects 1 to 5, wherein the step of obtaining the Raney nickel further includes a step of applying a slurry containing the NiAl alloy powder and a solvent to the substrate, and the NiAl alloy treated in the alkali treatment step is supported on the substrate. (Aspect 7) The method for manufacturing an electrode according to aspect 6, wherein the slurry further includes Ni metal powder, and the Ni metal may contain Al, the Ni content of the Ni metal is more than 50% by mass, and the amount of Al contained in the Ni metal is less than the amount of Ni. (Aspect 8) The method for manufacturing an electrode according to aspect 6 or 7, wherein the step of obtaining the Raney nickel includes a step of drying and firing the slurry applied in the coating step, and the alkali treatment step is performed after the firing step.(Aspect 9) A raw material for an electrode of a water electrolysis apparatus, comprising a base material, a NiAl alloy and Ni metal supported on the base material, wherein the NiAl alloy is a raw material for Raney nickel and dissolves aluminum with an alkaline substance, the Ni metal may contain Al, the Ni content of the Ni metal is more than 50% by mass, and the amount of Al contained in the Ni metal is less than the amount of Ni, and the component composition of the NiAl alloy excluding unavoidable impurities is the following compositional formula (I): Al. ３．００ Ni(2.00-(x+y))Cu ｘ Fe ｙ (I) A raw material for an electrode, represented by the following compositional formula (I): [In compositional formula (I), y is a value that satisfies 0.00 ≤ y ≤ 0.30, and when y is a value that satisfies y = 0.00, x is a value that satisfies 0.00 < x < 0.30, and when y is a value that satisfies 0.00 < y ≤ 0.30, x and y are values ​​that satisfy 0.00 < x + y ≤ 0.45 and 0.00 < x ≤ 0.40.] (Aspect 10) A slurry used in the manufacture of electrodes for a water electrolysis apparatus, wherein the slurry comprises NiAl alloy powder, Ni metal powder, and a solvent, the NiAl alloy is a raw material for Raney nickel and dissolves aluminum with an alkaline substance, the Ni metal may contain Al, the Ni content of the Ni metal is more than 50% by mass, and the amount of Al contained in the Ni metal is less than the amount of Ni, and the component composition of the NiAl alloy, excluding unavoidable impurities, is the following composition formula (I): Al ３．００ Ni(2.00-(x+y))Cu ｘ Fe ｙ (I) A slurry represented by the following formula: [In the composition formula (I), y is a value that satisfies 0.00 ≤ y ≤ 0.30, and when y is a value that satisfies y = 0.00, x is a value that satisfies 0.00 < x < 0.30, and when y is a value that satisfies 0.00 < y ≤ 0.30, x and y are values ​​that satisfy 0.00 < x + y ≤ 0.45 and 0.00 < x ≤ 0.40.]

[0113] The embodiments and examples disclosed herein should be considered in all respects to be illustrative and not restrictive. The scope of this disclosure is indicated by the claims rather than the foregoing description, and all modifications are intended to be in the sense and scope equivalent to the claims.

Claims

1. A method for manufacturing an electrode for a water electrolysis apparatus, wherein the electrode comprises a base material and Raney nickel supported on the base material, the manufacturing method includes a step of obtaining the Raney nickel, the step of obtaining the Raney nickel includes an alkali treatment step of dissolving aluminum from the NiAl alloy with an alkaline substance, and the component composition of the NiAl alloy excluding unavoidable impurities is the following composition formula (I): Al ３．００ Ni(2.00-(x+y))Cu ｘ Fe ｙ (I) A method for manufacturing an electrode, represented by the composition formula (I): [In composition formula (I), y is a value that satisfies 0.00 ≤ y ≤ 0.30, and when y is a value that satisfies y = 0.00, x is a value that satisfies 0.00 < x < 0.30, and when y is a value that satisfies 0.00 < y ≤ 0.30, x and y are values ​​that satisfy 0.00 < x + y ≤ 0.45 and 0.00 < x ≤ 0.40.] 2. The method for manufacturing an electrode according to claim 1, wherein x and y in the composition formula (I) are values ​​that satisfy 0.02 ≤ x < 0.28 and y = 0.

00.

3. The method for manufacturing an electrode according to claim 1, wherein x and y in the composition formula (I) are values ​​that satisfy 0.05 ≤ x + y ≤ 0.42, 0.00 < x ≤ 0.40, and 0.00 < y ≤ 0.

30.

4. The method for manufacturing an electrode according to claim 1 or 3, wherein in the composition formula (I), x and y are values ​​that satisfy 0.02 ≤ x ≤ 0.35 and 0.02 ≤ y ≤ 0.

28.

5. The method for manufacturing an electrode according to any one of claims 1 to 4, wherein the step of obtaining the Raney nickel further includes an oxidation step of oxidizing the surface of the porous body obtained by the alkali treatment step.

6. The method for manufacturing an electrode according to any one of claims 1 to 5, wherein the step of obtaining the Raney nickel further includes a step of applying a slurry containing the NiAl alloy powder and a solvent to the substrate, and the NiAl alloy treated in the alkali treatment step is supported on the substrate.

7. The method for manufacturing an electrode according to claim 6, wherein the slurry further comprises powder of Ni metal, the Ni metal may contain Al, the Ni content of the Ni metal is more than 50% by mass, and the amount of Al contained in the Ni metal is less than the amount of Ni.

8. The method for manufacturing an electrode according to claim 6 or 7, wherein the step of obtaining the Raney nickel includes a step of drying and firing the slurry applied in the coating step, and the alkali treatment step is performed after the firing step.

9. A raw material for an electrode in a water electrolysis apparatus, comprising a base material, a NiAl alloy and Ni metal supported on the base material, wherein the NiAl alloy is a raw material for Raney nickel and dissolves aluminum with an alkaline substance, the Ni metal may contain Al, the Ni content of the Ni metal is more than 50% by mass, and the amount of Al contained in the Ni metal is less than the amount of Ni, and the component composition of the NiAl alloy, excluding unavoidable impurities, is given by the following compositional formula (I): Al ３．００ Ni(2.00-(x+y))Cu ｘ Fe ｙ (I) A raw material for an electrode, represented by the following compositional formula (I): [In compositional formula (I), y is a value that satisfies 0.00 ≤ y ≤ 0.30, and when y is a value that satisfies y = 0.00, x is a value that satisfies 0.00 < x < 0.30, and when y is a value that satisfies 0.00 < y ≤ 0.30, x and y are values ​​that satisfy 0.00 < x + y ≤ 0.45 and 0 < x ≤ 0.40.] 10. A slurry used for manufacturing an electrode of a water electrolysis device, wherein the slurry contains NiAl alloy powder, Ni metal powder, and a solvent, the NiAl alloy is a raw material of Raney nickel and elutes aluminum with an alkaline substance, the Ni metal is a metal that may contain Al, the Ni content of the Ni metal is more than 50% by mass, and the amount of substance of Al contained in the Ni metal is smaller than the amount of substance of Ni, and the component composition excluding inevitable impurities of the NiAl alloy is represented by the following composition formula (I): Al ３．００ Ni(2.00 - (x + y))Cu ｘ Fe ｙ (I) [In the composition formula (I), y is a value satisfying 0.00 ≦ y ≦ 0.

30. When y satisfies y = 0.00, x is a value satisfying 0.00 < x < 0.

30. When y satisfies 0.00 < y ≦ 0.30, x and y are values satisfying 0.00 < x + y ≦ 0.45 and 0.00 < x ≦ 0.40.] The slurry represented by this is provided.

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