Method for manufacturing water electrolysis stack

Abstract

The present invention relates to a method for manufacturing a water electrolysis stack, comprising the steps of: preparing an acid-treated substrate (S1); assembling a membrane electrode assembly including the acid-treated substrate (S2); assembling a dry stack including the membrane electrode assembly (S3); preparing an electrolyte by mixing a Ni precursor and an Fe precursor with an electrolyte solution (S4); and injecting the electrolyte into the dry stack and activating the dry stack by applying an electrical load thereto (S5).

Description

Method for manufacturing a water electrolysis stack

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0164267 filed November 18, 2024, the entire contents of which are incorporated herein.

[0003] Technology field

[0004] The present invention relates to a method for manufacturing a water electrolysis stack with excellent initial current density.

[0005] Recently, in order to reduce reliance on fossil fuels and expand the use of renewable energy, research is actively underway on power generation systems based on renewable energy sources such as solar and wind power, as well as fuel cells.

[0006] Amidst the continuously rising demand for research and development of alternative energy due to global warming and the depletion of fossil fuels, hydrogen energy is garnering attention as the only practical alternative for solving environmental and energy problems.

[0007] When hydrogen is used as fuel, it produces almost no pollutants during combustion, which can solve the environmental pollution problems associated with current fossil fuels. Furthermore, since it can be manufactured using an infinite supply of water as a raw material, it is gaining attention as the ultimate alternative to the future depletion of fossil energy.

[0008] However, conventional hydrogen energy generation devices had a problem in which the initial current density decreased due to the detachment of the catalyst attached to the electrode surface caused by physical shock from the flow of the electrolyte.

[0009] The present invention aims to provide a method for manufacturing a water electrolysis stack with excellent initial current density.

[0010] [1] According to one embodiment of the present invention, a method for manufacturing a water electrolysis stack is provided, comprising the steps of: manufacturing an acid-treated substrate (S1); assembling a membrane-electrode assembly including the acid-treated substrate (S2); manufacturing a dry stack including the membrane-electrode assembly (S3); preparing an electrolyte by mixing a Ni precursor and an Fe precursor with an electrolyte solution (S4); and introducing the electrolyte into the dry stack and activating it by applying an electrical load (S5).

[0011] [2] In the above [1], the step (S1) may be performed by immersing the substrate in at least one solution selected from the group consisting of sulfuric acid (H2SO4) solution, hydrochloric acid (HCl) solution, hydrofluoric acid (HF) solution and nitric acid (HNO3) solution for 0.5 to 3 hours.

[0012] [3] In the above [2], the substrate may be at least one selected from the group consisting of nickel foam, nickel felt, nickel fiber paper, nickel sponge, nickel mesh, stainless steel foam and nickel plate.

[0013] [4] In at least one of [1] to [3] above, the Ni precursor and the Fe precursor may be mixed at a molar concentration of 0.01 mM to 100 mM based on the electrolyte.

[0014] [5] In at least one of [1] to [4] above, the Ni precursor may be at least one selected from the group consisting of NiCl2, NiCl2·6H2O, NiSO4·6H2O, Ni(NO3)2·6H2O, NiBr2, NiBr2·H2O, Ni(ClO4)·6H2O, Ni(OCOCH3)2·4H2O, (NH4)2Ni(SO4)2·6H2O and 2NiCO3·3Ni(OH)2·4H2O.

[0015] [6] In at least one of [1] to [5] above, the Fe precursor may be at least one selected from the group consisting of FeCl2, FeCl3, Fe(acac)2 and Fe(NO3)3.

[0016] [7] In at least one of [1] to [6] above, the molar ratio of Ni and Fe in the electrolyte may be 5.5 : 4.5 to 9.5 : 0.5.

[0017] [8] In at least one of [1] to [7] above, the electrolyte solution may be at least one selected from the group consisting of KOH, NaOH, Ca(OH)2, NH4OH, Ba(OH)2 and Mg(OH)2.

[0018] [9] In at least one of [1] to [8] above, the molar concentration of the electrolyte solution may be 0.01M to 1M.

[0019]

[0010] In at least one of [1] to [9] above, the step (S4) may be performed by further mixing at least one selected from the group consisting of Co precursor, Bi precursor and W precursor.

[0020]

[0011] In at least one of [1] to

[0010] above, the step (S5) can be performed by at least one method selected from the group consisting of chronopotentiometry, cyclovoltammetry, and chronoamperometry.

[0021]

[0012] In at least one of [1] to

[0011] above, the chronopotentiometry is 0.1 A / cm 2 Up to 2A / cm 2 It can be performed under current density conditions.

[0022] The method for manufacturing a water electrolysis stack according to the present invention can improve the electrochemical reaction rate by using an acid-treated substrate as the anode, thereby increasing the surface of the substrate to make it more precise and increasing the catalytic active sites and the contact area with the electrolyte. Additionally, by introducing the electrolyte into the dry stack and simultaneously applying an electrical load to activate it, the electrochemical reaction starts immediately during the initial activation stage, thereby improving the initial current density.

[0023] Figure 1 is a graph showing the current density according to the applied voltage (1.4V to 2.0V) measured by linear sweep voltammetry (LSV) of water electrolysis stacks prepared according to Example 1 and Comparative Examples 1 to 4.

[0024] Figure 2 shows the structure of a membrane electrode assembly.

[0025] Figure 3 shows the structure of a unit cell.

[0026] Figure 4 shows the structure of a dry stack.

[0027]

[0028] The present invention will be described in detail below.

[0029] Terms and words used in this specification and claims shall not be interpreted as being limited to their ordinary or dictionary meanings, but shall be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0030] The terms used herein are for describing the embodiments and are not intended to limit the invention. In this specification, the singular form includes the plural form unless specifically stated otherwise in the text. As used herein, "comprises" and / or "comprising" do not exclude the presence or addition of one or more other components in addition to the components mentioned.

[0031] In this specification, the term “Membrane Electrode Assembly” may refer to a structure comprising an anode, a cathode, and an anion exchange membrane, wherein the anode / anion exchange membrane / cathode are sequentially stacked.

[0032] In this specification, the term “unit cell” refers to a concept including a membrane electrode assembly, and may mean a structure in which an anode cell frame is stacked on the anode of the membrane electrode assembly, and a cathode cell frame and a current collector are sequentially stacked on the cathode.

[0033] In this specification, the term “dry stack” refers to a structure in which at least one unit cell is stacked and end plates are disposed on both sides of the stacked unit cell, and may mean a state before the water electrolysis stack is impregnated by the injection of an electrolyte.

[0034]

[0035] A method for manufacturing a water electrolysis stack according to the present invention comprises the steps of: manufacturing an acid-treated substrate (S1); assembling a membrane-electrode assembly including the acid-treated substrate (S2); assembling a dry stack including the membrane-electrode assembly (S3); preparing an electrolyte by mixing a Ni precursor and an Fe precursor with an electrolyte solution (S4); and introducing the electrolyte into the dry stack and activating it by applying an electrical load (S5).

[0036] The inventors discovered that the initial current density of a water electrolysis stack can be improved by increasing the electrochemical reaction rate through a combination of the five processes above, and completed the present invention.

[0037]

[0038] Hereinafter, each step of the method for manufacturing a water electrolysis stack according to one embodiment of the present invention will be described in detail.

[0039]

[0040] (S1) Step

[0041] In one aspect, the above step (S1) is a process for manufacturing an acid-treated substrate, specifically a process for acid-treating the substrate. Conventional anode substrates of water electrolysis stacks are not acid-treated, so the oxide layer on the substrate surface hinders the flow of current, and the initial activation reaction is delayed due to impurities on the substrate surface, resulting in a problem where the initial current density is inhibited.

[0042] On the other hand, when an acid-treated substrate as in the present invention is used as an anode, a nanoporous structure is formed on the surface of the substrate, which can promote the oxygen evolution reaction. Furthermore, oxide layers and impurities on the substrate surface are removed during the acid treatment process, resulting in a refined surface; consequently, the active sites of the catalyst increase, thereby expanding the contact area with the electrolyte. Additionally, such an acid-treated surface optimizes the electron transfer path and improves current flow, enabling the formation of a high-performance nickel-iron hydroxide catalyst layer on the substrate surface, which has the effect of excellent initial current density.

[0043] At this time, the substrate may be at least one selected from the group consisting of nickel foam, nickel felt, nickel fiber paper, nickel sponge, nickel mesh, stainless steel foam, and nickel plate, and preferably may be nickel foam. In the case of a nickel-based substrate, since it has a porous structure and a very large surface area, the contact area with the electrolyte can be maximized to expand the reaction area and improve the electrochemical reaction, thereby improving the performance of the water electrolysis stack.

[0044] The above step (S1) can be performed by immersing the substrate in at least one solution selected from the group consisting of sulfuric acid (H2SO4) solution, hydrochloric acid (HCl) solution, hydrofluoric acid (HF) solution, and nitric acid (HNO3) solution for 0.5 to 3 hours. In this case, the oxide layer on the surface of the substrate can be effectively removed. In addition, the nickel-iron hydroxide catalyst can grow well on the surface of the substrate, and the grown catalyst can be firmly fixed to the substrate, thereby stably maintaining the substrate in a water electrolysis environment.

[0045]

[0046] (S2) Step

[0047] In one aspect, the above step (S2) is a process for assembling a membrane electrode assembly including the acid-treated substrate.

[0048] The above membrane-electrode assembly includes the anode, cathode, and anion exchange membrane, and may have a structure in which the anode / anion exchange membrane / cathode are sequentially stacked. In this case, an oxygen evolution reaction occurs at the anode, and a hydrogen evolution reaction occurs at the cathode. Additionally, by including an anion exchange membrane capable of operating in a basic environment, inexpensive metals such as Ni, Fe, and Co can be utilized as catalysts, and Ni, Fe, and Co-based catalysts can induce rapid oxygen and hydrogen production.

[0049] According to one embodiment of the present invention, the anode may be an acid-treated substrate manufactured in step (S1).

[0050] Generally, the anode of a membrane-electrode assembly is manufactured by coating catalyst particles containing transition metals such as Fe, Ni, and Co onto a substrate, such as nickel foam, to ensure that the active component is sufficiently coated or supported on the substrate. However, in this case, physical shocks caused by the generation of gas bubbles or the flow of the electrolyte during the operation of the water electrolysis stack lead to the detachment of catalyst particles attached to the substrate surface. As the catalyst particles detach, the performance of the oxygen evolution reaction rapidly decreases, leading to the failure of the water electrolysis stack. Furthermore, the use of ionomers or binders to coat the catalyst particles increases the cost and complexity of electrode fabrication, and there is a limitation in that it is difficult to uniformly coat the catalyst particles even into the interior of the substrate when using thick substrates of several millimeters.

[0051] According to one embodiment of the present invention, a membrane-electrode assembly is assembled without the acid-treated substrate being immersed in an activating component, and subsequently, the catalyst particles are mixed into the electrolyte and the electrolyte is introduced, thereby forming a catalyst layer on the surface of the acid-treated substrate during the activation process, which prevents the phenomenon of the catalyst particles on the substrate surface being detached. Furthermore, even when using a thick substrate with a thickness of several millimeters, the catalyst layer can be uniformly formed throughout the interior of the substrate by circulating and activating the electrolyte so that it passes through the interior of the substrate.

[0052] In addition, the anode may be assembled such that the conductive surface of the acid-treated substrate is positioned on the anion exchange membrane to increase current transfer efficiency.

[0053] The above cathode may include a catalyst layer and a porous transport layer. The catalyst layer may be a carbon felt coated with at least one catalyst selected from the group consisting of Pt / C, PtRu / C, Ru / C, Pd / C, NiMo, and NiFe, or a carbon paper coated with at least one catalyst selected from the group consisting of Pt / C, PtRu / C, Ru / C, Pd / C, NiMo, and NiFe, but is not limited thereto. Additionally, the porous transport layer may be at least one selected from the group consisting of nickel foam, nickel felt, nickel fiber paper, nickel sponge, nickel mesh, and stainless steel foam, but is not limited thereto. In this way, when the above cathode includes a catalyst layer and a porous transport layer, the membrane electrode assembly may have a structure in which an anode / anion exchange membrane / catalyst layer / porous transport layer are sequentially stacked.

[0054]

[0055] (S3) Step

[0056] The above step (S3) is a process of assembling a dry stack including the membrane electrode assembly.

[0057] As described above, the dry stack of the present invention comprises at least one unit cell, and the unit cell comprises a membrane electrode assembly.

[0058] The above dry stack has a structure in which at least one unit cell is stacked in the middle section, and end plates are stacked on both sides of the stacked unit cells. At this time, the end plates may be made of stainless steel.

[0059] The above unit cell may have a structure in which an anode cell frame and an anode bipolar plate are sequentially stacked on the anode of the membrane electrode assembly, and a cathode cell frame and a cathode bipolar plate are sequentially stacked on the cathode of the membrane electrode assembly. Preferably, at least one gasket or O-ring may be added between the cell frames and bipolar plates of the anode and cathode, respectively, to prevent fluid leakage and maintain a hermetic structure. At this time, the positive cell frame and the negative cell frame may each be one or more selected from the group consisting of polytetrafluoroethylene (PTFE), polyphenol sulfide (PPS), and polyether ether ketone (PEEK), and the positive bipolar plate and the negative bipolar plate may each be one or more selected from the group consisting of nickel plate (Ni Plate), stainless steel plate, nickel-plated stainless steel plate, and nickel-plated steel plate.

[0060] The above dry stack can be assembled by stacking at least one unit cell in the middle section, placing an end plate on the surface section, and then applying a pressure of 380,000 Pa to 3,800,000 Pa using a hydraulic press. At this time, since the electrolyte is not introduced into the dry stack during the assembly stage, the acid-treated substrate can be adjusted to be compatible with the electrolyte flow path so that the water electrolysis stack can subsequently receive the electrolyte uniformly.

[0061]

[0062] (S4) Step

[0063] The above step (S4) is a process of preparing an electrolyte by mixing a Ni precursor and an Fe precursor with an electrolyte solution.

[0064] Generally, the electrolyte is OH capable of effectively transmitting current within the water electrolysis stack. - The electrolyte does not contain separate catalyst particles because it contains a basic solution such as KOH to provide ions and uses a substrate with a formed catalyst layer.

[0065] However, according to one embodiment of the present invention, since the membrane electrode assembly is assembled with a substrate that is not supported on an active component to prevent the detachment of catalyst particles as described above, it may be characterized by separately mixing catalyst raw materials such as Ni precursors and Fe precursors into the electrolyte solution. In this case, when an electrical load is applied while the electrolyte is subsequently introduced into the dry stack, Ni ions and Fe ions contained in the electrolyte are electrodeposited on the substrate to form a Ni-Fe hydroxide catalyst layer having a nanoporous structure, and accordingly, a NiFe-LDH (Layered-Double Hydroxide) with an Fe content of 25% to 33% is formed in the part close to the substrate, thereby promoting the oxygen evolution reaction.

[0066] The above Ni precursor and the above Fe precursor may be mixed at a molar concentration of 0.01 mM to 100 mM, preferably 1 mM to 10 mM, based on the electrolyte. When the above range is satisfied, the concentrations of Ni and Fe ions in the electrolyte are optimized for the electrochemical catalytic reaction, preventing excessive metal deposition and maximizing reaction efficiency.

[0067] The above Ni precursor may be at least one selected from the group consisting of NiCl2, NiCl2·6H2O, NiSO4·6H2O, Ni(NO3)2·6H2O, NiBr2, NiBr2·H2O, Ni(ClO4)·6H2O, Ni(OCOCH3)2·4H2O, (NH4)2Ni(SO4)2·6H2O, and 2NiCO3·3Ni(OH)2·4H2O, and preferably may be NiCl2. The above Ni precursor dissolves well in a basic solution and can uniformly supply Ni ions.

[0068] The above Fe precursor may be at least one selected from the group consisting of FeCl2, FeCl3, Fe(acac)2, and Fe(NO3)3, and preferably FeCl2. The above Fe precursor dissolves well in basic solutions and effectively combines with Ni ions in the electrolyte to promote the formation of Ni-Fe hydroxide, thereby reducing the activation energy of the oxygen evolution reaction.

[0069] The molar ratio of Ni and Fe in the electrolyte may be 5.5 : 4.5 to 9.5 : 0.5, preferably 7 : 3 to 9 : 1. When the above range is satisfied, Ni having an optimal Ni:Fe ratio x Fe y The formation of an OOH phase reduces the activation energy of the oxygen evolution reaction, which can improve the performance of the water electrolysis stack.

[0070] The above electrolyte solution may be at least one selected from the group consisting of KOH, NaOH, Ca(OH)2, NH4OH, Ba(OH)2, and Mg(OH)2, and preferably may be KOH. OH contained in the basic solution - Ions react with Ni or Fe precursors in the electrolyte solution, and Ni x Fe yIt plays an important role in forming an OOH-type catalyst layer. In addition, a strongly basic solution creates a pH environment favorable for the oxygen evolution reaction, and when used as an electrolyte, it provides high ionic conductivity, which can promote oxidation and reduction reactions.

[0071] The molar concentration of the above electrolyte solution may be 0.01M to 1M, and preferably 0.1M to 0.5M. When the above range is satisfied, the ionic conductivity of the electrolyte is optimized so that current can flow smoothly, and the catalytic activity of the oxygen evolution reaction and hydrogen evolution reaction can be maximized.

[0072] The above step (S4) may be performed by further mixing at least one selected from the group consisting of Co precursor, Bi precursor and W precursor. In this case, the reactivity and electrical conductivity of the catalyst are improved by increasing the electron mobility between Ni and Fe atoms, and a stable structure is formed to prevent ion loss, thereby allowing the catalyst to remain structurally stable even during long-term operation.

[0073]

[0074] (S5) Step

[0075] The above step (S5) is a process of introducing the electrolyte into the dry stack and applying an electrical load to activate it. Conventionally, when the water electrolysis stack is driven without introducing an electrical load separately, the time for the electrolyte to penetrate the substrate and activate is prolonged, and the electrode surface is not activated evenly but reacts only partially, resulting in a problem of reduced uniformity of water electrolysis stack performance.

[0076] Accordingly, the present invention provides a method for reducing the initial current density by activating a dry stack in real time by introducing the electrolyte into the dry stack and applying an electrical load. In this case, a catalyst layer is formed on the surface of the acid-treated substrate from the moment the electrolyte is introduced due to the electrical load, and an electrochemical reaction begins, thereby shortening the initial activation time of the water electrolysis stack. Furthermore, by applying the electrical load, an electric field is formed, causing the electrolyte to diffuse more evenly and penetrate uniformly into the micropores or surface of the acid-treated substrate, thereby activating the electrochemical reaction and improving the initial current density.

[0077] The above step (S5) can be performed by at least one method selected from the group consisting of chronopotentiometry, cyclovoltammetry, and chronoamperometry, and preferably by chronopotentiometry. Chronopotentiometry is a method of applying a constant current to the acid-treated substrate for a certain period of time, cyclovoltammetry is a method of observing a change in current while repeatedly changing the voltage, and chronoamperometry is a method of inducing a current response while applying a constant voltage.

[0078] Specifically, when a dry stack is activated using the above-mentioned chronopotentiometry, oxide layers or impurities present on the electrode surface are removed, which has the effect of lowering the initial current density, and the evenly maintained current can promote uniform activation across the entire electrode surface.

[0079] In this case, the above chronopotentiometry is 0.1 A / cm 2 Up to 2A / cm 2It can be performed under current density conditions. When the above range is satisfied, impurities on the surface of the acid-treated substrate can be removed, the electrolyte penetrates into the micropores of the electrode, increasing the contact area between the substrate and the electrolyte, and the electrolyte is evenly distributed on the surface of the electrode by the electric field, thereby promoting the activation of the electrode.

[0080]

[0081] As described above, the present invention manufactures a water electrolysis stack by assembling a dry stack using an acid-treated substrate as the anode, introducing an electrolyte solution mixed with a Ni precursor and an Fe precursor into the dry stack, and applying an electrical load. This promotes the reaction between the dry stack and the electrolyte solution in the initial stage, thereby improving the electrochemical reaction rate and enabling excellent initial performance.

[0082]

[0083] The present invention will be explained in more detail below through specific embodiments.

[0084] Embodiments according to the present invention may be modified in various different forms, and the scope of the present invention should not be interpreted as being limited to the embodiments described below. The embodiments of the present invention are provided to more fully explain the present invention to those with average knowledge in the art.

[0085]

[0086] Examples and Comparative Examples

[0087] Example 1

[0088] (1) Acid-treated substrate manufacturing step

[0089] Nickel foam (Ni Foam) as a substrate was immersed in a 0.5 M sulfuric acid (H2SO4) solution and acid-treated for 1 hour to remove impurities and an oxide layer from the surface of the nickel foam (Ni Foam). Afterward, the sulfuric acid (H2SO4) residue was washed with distilled water and dried for 12 hours to produce an acid-treated substrate.

[0090]

[0091] (2) Membrane Electrode Assembly Assembly Step

[0092] The acid-treated substrate prepared above was used as the anode, and a cathode comprising a catalyst layer (carbon paper coated with Pt / C and PtRu / C) and a porous transport layer (nickel foam (Ni Foam)) was prepared, and then an anion exchange membrane (Sustainion of Dioxide Materials) was placed between the anode and the cathode to assemble a membrane-electrode assembly.

[0093]

[0094] (3) Dry stack assembly step

[0095] A unit cell was manufactured by sequentially stacking an anode cell frame (polytetrafluoroethylene) and a bipolar plate (nickel plate) on the anode of the above membrane electrode assembly, and sequentially stacking a cathode cell frame (polytetrafluoroethylene) and a bipolar plate (nickel plate) on the cathode of the above membrane electrode assembly.

[0096] Afterwards, the above 23 unit cells were stacked in succession, end plates (stainless steel) were placed on each side, and a dry stack was assembled by applying a pressure of 1,900,000 Pa with a hydraulic press.

[0097]

[0098] (4) Electrolyte preparation step

[0099] An electrolyte was prepared by mixing NiCl2 and FeCl2 in a 0.3M KOH solution such that the molar ratio of Ni to Fe was 8 to 2.

[0100]

[0101] (5) Activation step

[0102] Afterwards, the electrolyte is injected into the dry stack assembled in step (3) at a rate of 2300 L / min, and simultaneously, through chronopotentiometry, at a rate of 0.6 A / cm² for 1 hour until the potential reaches 1.8 V. 2 A water electrolysis stack was manufactured by activating a dry stack by applying current under current density conditions.

[0103]

[0104] Comparative Example 1

[0105] A water electrolysis stack was manufactured in the same manner as in Example 1, except that the above (1) acid-treated substrate manufacturing step was omitted and an acid-untreated nickel foam (Ni Foam) was used.

[0106]

[0107] Comparative Example 2

[0108] In the above (4) electrolyte preparation step, a water electrolysis stack was prepared in the same manner as in Example 1, except that FeCl2 was not mixed and NiCl2 was mixed at a molar concentration of 1 mM.

[0109]

[0110] Comparative Example 3

[0111] In the above (4) electrolyte preparation step, a water electrolysis stack was prepared in the same manner as in Example 1, except that NiCl2 was not mixed and FeCl2 was mixed at a molar concentration of 5 mM.

[0112]

[0113] Comparative Example 4

[0114] In the above (5) activation step, the electrolytic water stack was manufactured in the same manner as in Example 1, except that the electrolyte was introduced into the dry stack and activated without applying an electrical load.

[0115]

[0116] Experimental Example: Evaluation of Initial Current Density

[0117] The current density of the water electrolysis stacks prepared according to Example 1 and Comparative Examples 1 to 4 was measured according to the applied voltage (1.4V to 2.0V) using Linear Sweep Volutammetry (LSV).

[0118] The measurement results are shown in Figure 1, and the current density at 1.8V is shown in Table 1 below for comparison of the initial current density.

[0119] Initial current density [A / cm²] 2 Example 10.73 Comparative Example 10.49 Comparative Example 20.61 Comparative Example 30.58 Comparative Example 40.21

[0120]

[0121] Through Table 1 above and Figure 1 below, it can be seen that the water electrolysis stack manufactured according to the manufacturing method of Example 1 has a superior initial current density compared to the water electrolysis stack manufactured according to the manufacturing methods of Comparative Examples 1 to 4.

[0122]

[0123] [Explanation of the symbol]

[0124] 100: Membrane-electrode assembly

[0125] 101: Anion exchange membrane

[0126] 102: Anode

[0127] 103: Catalyst layer

[0128] 104: Porous transport layer

[0129] 105: Cathode

[0130] 110: Unit cell

[0131] 111: Positive cell frame

[0132] 112: Positive bipolar plate

[0133] 113: Cathode cell frame

[0134] 114: Cathode bipolar plate

[0135] 120: Dry stack

[0136] 121, 122: End plates

[0137]

Claims

1. Step of manufacturing an acid-treated substrate (S1); Step (S2) of assembling a membrane electrode assembly including the acid-treated substrate; Step (S3) of assembling a dry stack including the above membrane electrode assembly; A step of preparing an electrolyte by mixing Ni precursors and Fe precursors with an electrolyte solution (S4); and A method for manufacturing a water electrolysis stack comprising the step (S5) of introducing the above electrolyte into the above dry stack and activating it by applying an electrical load.

2. In Claim 1, The above step (S1) is a method for manufacturing a water electrolysis stack, wherein the substrate is immersed for 0.5 to 3 hours in at least one solution selected from the group consisting of sulfuric acid (H2SO4) solution, hydrochloric acid (HCl) solution, hydrofluoric acid (HF) solution, and nitric acid (HNO3) solution.

3. In Claim 2, A method for manufacturing a water electrolysis stack in which the substrate is at least one selected from the group consisting of nickel foam, nickel felt, nickel fiber paper, nickel sponge, nickel mesh, stainless steel foam, and nickel plate.

4. In Claim 1, A method for manufacturing a water electrolysis stack in which the above Ni precursor and the above Fe precursor are mixed at a molar concentration of 0.01 mM to 100 mM based on the electrolyte.

5. In Claim 1, A method for manufacturing a water electrolysis stack in which the above Ni precursor is at least one selected from the group consisting of NiCl2, NiCl2·6H2O, NiSO4·6H2O, Ni(NO3)2·6H2O, NiBr2, NiBr2·H2O, Ni(ClO4)·6H2O, Ni(OCOCH3)2·4H2O, (NH4)2Ni(SO4)2·6H2O, and 2NiCO3·3Ni(OH)2·4H2O.

6. In Claim 1, A method for manufacturing a water electrolysis stack in which the above Fe precursor is at least one selected from the group consisting of FeCl2, FeCl3, Fe(acac)2 and Fe(NO3)3.

7. In Claim 1, A method for manufacturing a water electrolysis stack in which the molar ratio of Ni and Fe in the above electrolyte is 5.5 : 4.5 to 9.5 : 0.

5.

8. In Claim 1, A method for manufacturing a water electrolysis stack in which the above electrolyte solution is at least one selected from the group consisting of KOH, NaOH, Ca(OH)2, NH4OH, Ba(OH)2, and Mg(OH)2.

9. In Claim 1, A method for manufacturing a water electrolysis stack in which the molar concentration of the above electrolyte solution is 0.01M to 1M.

10. In Claim 1, The above step (S4) is a method for manufacturing a water electrolysis stack, wherein at least one selected from the group consisting of a Co precursor, a Bi precursor, and a W precursor is further mixed.

11. In Claim 1, The above step (S5) is a method for manufacturing a water electrolysis stack, performed by at least one method selected from the group consisting of chronopotentiometry, cyclovoltammetry, and chronoamperometry.

12. In Claim 11, The above chronopotentiometry is 0.1 A / cm 2 Up to 2A / cm 2 A method for manufacturing a water electrolysis stack performed under current density conditions.

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