Method for manufacturing electrode for water electrolysis for hydrogen production

Abstract

The present invention relates to an electrode for water electrolysis for hydrogen production and a manufacturing method therefor. The manufacturing method according to the present invention achieves a simpler process compared with an existing iridium (IrO2) electrode manufacturing process, uses low thermal energy, shortens the time required for, especially, heat curing, facilitates the thickness adjustment of a coating layer, and can manufacture an electrode for water electrolysis at relatively low facility costs and manufacturing costs, and requires less time, labor, and energy to perform steps of the process. In addition, the electrode for water electrolysis obtained by the manufacturing method according to the present invention not only possesses generally required electrochemical stability and chemical resistance, but also exhibits high discharge efficiency of generated bubbles while preventing defects due to voids in an actual hydrogen manufacturing process.

Description

Method for manufacturing a water electrolysis electrode for hydrogen production

[0001] Cross-reference to related applications

[0002] This disclosure claims priority to Patent Application No. 10-2023-0168100, filed November 28, 2023, and Patent Application No. 10-2024-0170320, filed November 26, 2024, the entire contents of each of which are incorporated herein by reference.

[0003] Statement on Government Support

[0004] This disclosure was made possible with support from the '2023 Preliminary Hydrogen Specialized Company Development Support Project' managed by Pohang Technopark, located in Pohang, Gyeongsangbuk-do, Republic of Korea.

[0005] Technology field

[0006] The present invention relates to a water electrolysis electrode for hydrogen production and a method for producing the same.

[0007] Recently, efforts to reduce carbon emissions are intensifying across various sectors. This is premised on the adoption of new energy sources in various industries. While efforts are being made to curb carbon emissions by improving the efficiency of existing facilities and equipment, alternative energy sources are emerging as a key improvement strategy. In reality, the overall carbon reduction achieved through efficiency improvements is minimal, as the carbon emissions from Scope 2 electricity generation are difficult to reduce.

[0008] Although there is a trend toward replacing existing fossil fuels with renewable energy, there is a problem of difficulty in coping with fluctuations in energy production due to climate, such as causing instability in the power grid.

[0009] Nuclear power can be utilized as a means of stabilizing the power supply. While nuclear power is an effective means of achieving neutrality in terms of total carbon emissions, it poses numerous safety issues due to issues such as radioactivity and spent fuel rods.

[0010] Furthermore, hydrocarbon fuels (gasoline, diesel, etc.) used in internal combustion engines, the primary means of transportation today, account for a significant portion of total carbon emissions. Electric vehicles, whose adoption has recently been increasing, continue to face the challenge of increased electricity consumption.

[0011] To address these issues, the use of hydrogen as a new energy source has recently been proposed, and as related technologies advance, its use is rapidly increasing, coupled with a reduction in manufacturing costs and improvements in the overall supply chain, including production, transportation, distribution, and supply.

[0012] However, most hydrogen currently in use is gray hydrogen produced through high-temperature reforming of liquefied natural gas (LNG), and the actual production and use of green hydrogen is limited. This is because the process of water electrolysis using electric energy involves the process of electrolyzing water to produce hydrogen using supplied electric energy. Therefore, if the electric energy input into green hydrogen production is not supplied by renewable and / or nuclear energy, it is inferior in both total carbon emissions and economic feasibility.

[0013] Another problem with the traditionally used electrolysis process is related to the supply of electrolyte to maintain electrical conductivity and the discharged by-products.

[0014] In general, the process of generating hydrogen through electrolysis is as follows.

[0015] [Overall reaction] 2H2O(l) → 2H2(g) + O2(g)

[0016] [Reduction electrode] 2H2O(l) + 2e - →H2(g) + 2OH - (aq)

[0017] [Oxidizing electrode] H2O(l) → O2(g)+ 2H + (aq) + 2e -

[0018] However, when only pure water (Water, H2O) exists as described above, the electrolysis process does not occur because current cannot flow through the water due to the lack of ions that contribute to electrical conductivity.

[0019] In reality, it is common for NaCl to act as an electrolyte, like seawater, and this NaCl acts as an electrolyte while Cl at the anode. - This causes a problem of generating chlorine (Cl2) gas, a by-product caused by ions. In other words, a solution is needed to address the problem of chlorine gas being generated in proportion to the total amount of hydrogen generated.

[0020] The electrolysis reaction using seawater is as follows.

[0021] [Overall reaction] 2Cl - + 2H2O → Cl2+ H2+ 2OH -

[0022] [Cathode] 2H2O + 2e- → H2+ 2OH -

[0023] [Anode] 2Cl - → Cl2+ 2e-

[0024] Furthermore, the anode suffers from electrochemical corrosion and persistent corrosion due to the generated chlorine, which drastically shortens the electrode life. Due to these issues, iridium (IrO2)-coated electrodes are typically used. However, the use of iridium electrodes in large-scale facilities entails significant cost increases and management challenges.

[0025] As a way to solve the problems related to NaCl electrolysis, an alkaline electrolysis cell (AEC) method is being used. This is a method that replaces the existing NaCl electrolysis process with Cl - This is a method of causing electrolysis in an alkaline environment to solve problems caused by ions.

[0026] The reaction of alkaline water electrolysis is as follows.

[0027] [Overall reaction] 4OH - + 4H2O → O2+ 2H2+ 2H2O

[0028] [Cathode] 4H2O + 4e- → 2H2+ 4OH -

[0029] [Positive] 4OH - → O2+ 2H2O + 4e-

[0030] Cl - OH instead of ion - Since ions are generated, corrosion problems caused by chloride ions or chlorine gas can be alleviated. However, the need for large amounts of alkali (primarily NaOH) also leads to a sharp increase in the cost of hydrogen production. Even in this case, the problem of persistent electrochemical corrosion and dissolution of the water electrolysis electrode persists.

[0031] In addition to the above-mentioned electrolysis, low-temperature electrolysis processes include polymer electrolyte membrane electrolysis (PEM) and anion exchange membrane electrolysis (AEM), which use membranes. In these electrolysis processes, the electrode for electrolysis is a major technological barrier.

[0032] Electrodes for water electrolysis require high stability against electrochemical corrosion during water electrolysis, chemical resistance to electrolytes, and effective desorption (desorption) of hydrogen and oxygen generated on the electrode surface. Considering these electrochemical stability and chemical resistance, nickel-based electrodes are typically used in the AEM process. The PEM process primarily uses electrodes made of titanium (Ti) as a base plate with a layer of iridium (IrO2), a platinum group element, formed on its surface. These iridium-coated electrodes, in addition to manufacturing process issues, are extremely expensive, posing significant obstacles to the construction and operation of electrode manufacturing facilities.

[0033] Electrodes used in the water electrolysis process for hydrogen production require two critical properties: long-term chemical resistance and electrochemical corrosion stability in the electrolyte, and the maintenance of a surface potential for hydrogen and oxygen generation. Electrodes primarily made of IrO2, an oxide of the platinum group element iridium, are commonly used to meet these requirements. Iridium exhibits excellent process stability and satisfies both the required electrochemical and general chemical resistance. Furthermore, with a surface resistance in the tens of milliohms (mΩ), it demonstrates excellent surface potential stability for hydrogen generation.

[0034] However, due to the characteristics of IrO2 material, there are issues with the price and difficulties in the process of forming the coating layer. In the case of electrodes using IrO2 material, IrO2 material is generally coated on the surface of a titanium plate with a thickness of 10 to 20 ㎛. IrO2 material is very expensive (approximately 600,000 to 800,000 won / g), and the amount of IrO2 material required per 1 m2 of electrode is approximately 40 g (when formed with a thickness of 10 ㎛), so the cost of purchasing IrO2 to manufacture 1 m2 of electrode is approximately 24 million to 32 million won, so there is a need to alleviate the burden of manufacturing costs.

[0035] Meanwhile, since IrO2 material is a chemically resistant substance that does not dissolve in acids or organic solvents, for coating, powdered IrO2 must be suspended in a solution containing a binder and a solvent, coated on the surface of a titanium plate, and then heat-treated at approximately 600°C. This process must be repeated dozens of times to form an IrO2 coating layer of the desired thickness. In the conventional manufacturing process of an electrode with an IrO2 coating layer, not only does the coating process take a long time, but the heat treatment equipment must be maintained at high temperatures for a long period of time, which consumes a large amount of energy.

[0036] There has been a persistent need in the industry to develop an electrode that can replace an electrolytic electrode having a coating layer based on IrO2 material, as well as a manufacturing method for manufacturing such an electrode cost-effectively.

[0037] The inventors of the present invention confirmed that a conventional electrolysis electrode having a coating layer based on IrO2 material can be replaced by using graphite, a type of carbon material, and forming a coating layer on the surface of a water electrolysis electrode using a PVDF binder, thereby completing the present invention.

[0038] The purpose of the present invention is to provide a method for manufacturing an electrode having a graphite coating layer that can replace a conventional electrolysis electrode having a coating layer based on IrO2 material.

[0039] The purpose of the present invention is to provide an electrode for water electrolysis manufactured by a method for manufacturing an electrode having a graphite coating layer.

[0040] The present invention has been made to solve the above-mentioned problems, and provides a method for manufacturing a water electrolysis electrode having a flake graphite coating layer, the method comprising: (1) applying a surface roughening treatment to a base metal plate for manufacturing a water electrolysis electrode to provide surface roughness; (2) applying a chemical corrosion treatment to the base metal plate with the surface roughness provided to stabilize the surface roughness; (3) mixing and stirring flake graphite and PVDF (polyvinylidene fluoride) to obtain size-controlled flake graphite particles; (4) adding the obtained flake graphite particles to an NMP (n-methyl-2-pyrrolidone) solution to prepare a coating solution; (5) spraying the prepared coating solution onto the base metal plate with the stabilized surface roughness to form a coating layer; and (6) applying heat to the plate with the coated layer formed to obtain a plate with a thermosetting flake graphite coating layer, and then molding the plate.

[0041] The method for manufacturing a water electrolysis electrode according to the present invention is simpler than the existing iridium (IrO2) electrode manufacturing process, uses less heat energy, and can manufacture a coating layer of a desired thickness in a particularly short curing time, so it has high industrial utility value. In addition, the method for manufacturing a water electrolysis electrode according to the present invention has the advantages of being able to manufacture a water electrolysis electrode with relatively low equipment and manufacturing costs, and requiring less time, labor, and energy to perform the process steps. In addition, the water electrolysis electrode manufactured by the manufacturing method according to the present invention not only has the electrochemical stability and chemical resistance typically required, but also has the advantage of high bubble discharge efficiency generated during the actual hydrogen production process.

[0042] Figure 1 schematically illustrates a manufacturing process of an electrode for electrolysis according to one embodiment of the present invention.

[0043] Figure 2 schematically illustrates the structural features of a water electrolysis electrode manufactured according to one embodiment of the present invention.

[0044] As schematically illustrated in Fig. 1, the present invention relates to a method for manufacturing a water electrolysis electrode having a graphite coating layer formed thereon.

[0045] The method for manufacturing a water electrolysis electrode according to the present invention comprises the steps of: (1) applying a surface roughening treatment to a base metal plate for manufacturing a water electrolysis electrode to impart surface roughness; (2) applying a chemical corrosion treatment to the base metal plate with the imparted surface roughness to stabilize the surface roughness; (3) mixing and stirring flake graphite and PVDF (polyvinylidene fluoride) to obtain sized flake graphite particles; (4) adding the obtained flake graphite particles to an NMP (n-methyl-2-pyrrolidone) solution to prepare a coating solution; (5) spraying the prepared coating solution onto the base metal plate with the stabilized surface roughness to form a coating layer; and (6) applying heat to the plate with the formed coating layer to obtain a plate with a heat-cured flake graphite coating layer, and then molding the plate.

[0046] Below, the method for manufacturing an electrode for electrolysis according to the present invention is described in more detail for each step.

[0047] S1 - Step of providing a certain roughness (roughness) on the surface of the base metal plate

[0048] In the present invention, the base metal plate is commercially available and can be used without any particular limitations as long as it is made of titanium (Ti), stainless steel (STS), or nickel (Ni) alloy material. Prior to forming surface roughness (roughness) on the surface of the obtained alloy material, a surface flattening process such as acid treatment may be performed.

[0049] After the surface of the base metal plate is uniformly processed, various metal surface treatment methods, such as the shot blasting method, can be used to initially form surface roughness. By creating or imparting a uniform surface roughness to the metal surface that serves as the base layer of the electrode, the adhesion and / or bonding between the base metal surface and the coating solution containing the graphite particles can be enhanced.

[0050] In the present invention, the surface roughness (roughness) can be formed to a depth of 2 to 20 ㎛, preferably 5 to 18 ㎛, and most preferably 9 to 15 ㎛ based on the surface layer (outermost surface layer) of the base metal plate (see Fig. 2).

[0051] Surface roughness (roughness) can be appropriately adjusted in consideration of the performance of the electrode to be manufactured, such as electrochemical durability, service life, and hydrogen production efficiency.

[0052] S2 - Stabilizing surface roughness through chemical corrosion treatment

[0053] The final adjusted surface roughness is formed by applying an electrochemical corrosion method to a base metal plate having a primarily given surface roughness.

[0054] The electrochemical corrosion method used in this process can be applied by appropriately modifying a method known in the art.

[0055] S3 - Step to obtain sized impression graphite particles

[0056] Spherical graphite obtained through conventional milling exhibits a characteristic of denser grain boundaries as the graphite is finely divided. Consequently, to maintain sufficient grain boundaries, it must be processed into ultrafine particles (nano-sized). However, when mixed with binders and solvents, this ultrafine graphite exhibits poor dispersibility, making it difficult to handle during the coating process and preventing the formation of a coating layer of the desired thickness.

[0057] Furthermore, when using spherical graphite, the concentration of carbon or graphite powder in the solution varies significantly during the manufacturing process of the coating solution, making it difficult to form a uniform coating layer. To address this, a method of increasing the particle size is available. However, this method still presents a problem: the distribution of large particles causes electrolyte penetration, resulting in the inflow of electrolyte and ions, which cause corrosion, through the grain boundaries of the coating layer.

[0058] The inventors of the present invention confirmed that when spherical graphite is used instead of spherical graphite, the miscibility with the binder component and solvent is excellent, a coating layer can be formed with a desired thickness, and the coating structure after heat treatment is also maintained stably for a long period of time.

[0059] By mixing the graphite particles with a binder and a solvent, it is possible to have particles of a sufficient size for easy dispersion, and since the particles have a plate-like shape, a coating layer having a structure with a very dense grain boundary can be formed despite the relatively large particle size due to the overlapping (stacking) of the plate-like particles.

[0060] The impression graphite used in the present invention can be selected from among those available on the market, having a purity of at least 99%, preferably at least 99.5%, and an average particle size of 1 to 100 ㎛, preferably 30 to 90 ㎛, more preferably 40 to 70 ㎛, and most preferably 45 to 55 ㎛.

[0061] A binder component is used to form a surface layer film of the electrode using impression graphite. This binder component is used to effectively bond the impression graphite particles and to strengthen and stably maintain their adhesion to the electrode (metal) surface.

[0062] The present invention is characterized by using PVDF exhibiting superhydrophobicity. This PVDF can be selected from commercially available products in powder form with a particle size of 1 to 50 ㎛ and a density of 1.5 to 2.0 g / cm3 (at 25°C).

[0063] The particle size of the impression graphite particles can be adjusted by mixing impression graphite and PVDF at a certain ratio. At this time, the mixing ratio is 5 to 200 parts by weight, preferably 50 to 150 parts by weight, and more preferably 90 to 130 parts by weight, of PVDF based on 100 parts by weight of impression graphite. It is advantageous to maintain the above-mentioned mixing ratio in terms of the dispersibility of the impression graphite particles in the coating solution, the uniformity of the current flowing to the electrode during electrolysis, and the durability of the coating and electrode.

[0064] After mixing the impression graphite and PVDF, the size and shape of the impression graphite are appropriately adjusted by stirring at low speed so that the PVDF is combined with the impression graphite, and then the impression graphite particles having the desired size and shape are separated through a sieve.

[0065] S4 - Step of preparing a coating solution by mixing impression graphite particles and a solvent.

[0066] To manufacture a coating solution, the graphite particles obtained after the fractionation process must be dissolved in a suitable solvent.

[0067] The coating solution typically has a viscosity above a certain level. If it exceeds this threshold, it becomes difficult to form a uniformly thick coating layer on the base metal surface. Specifically, precise control of the coating thickness is impossible, and the resulting non-uniformity of the coating layer hinders the production of a water electrolysis electrode that exhibits optimal performance.

[0068] The inventors of the present invention have confirmed that when the obtained impression graphite particles after the fractionation process are mixed with an NMP (n-methyl-2-pyrrolidone) solvent and the viscosity of the coating solution is adjusted to a range of 10 to 500 cP, preferably 50 to 350 cP, and more preferably 100 to 200 cP, a coating layer can be formed with a desired thickness during the coating process, and the coating structure after heat treatment is also stably maintained for a long period of time.

[0069] It is recommended to use NMP with a purity of 99% or higher, commercially available. The NMP stock solution should not contain solid impurities or other organic components.

[0070] After the fractionation process, the size-adjusted graphite particles obtained, more specifically, the size-adjusted graphite particles whose size and / or shape are adjusted due to bonding / attachment with PVDF, are mixed with NMP at a certain ratio to prepare a coating solution having an appropriate viscosity. At this time, the mixing ratio is 80 to 120 parts by weight, preferably 90 to 110 parts by weight, and more preferably 100 parts by weight, of NMP based on 100 parts by weight of the size-adjusted graphite particles. It is advantageous to maintain the above-mentioned mixing ratio in terms of the dispersibility of the size-adjusted graphite particles in the coating solution, the uniformity of the current flowing through the electrode during electrolysis, and the durability of the coating and electrode.

[0071] S5 - Step of spray coating the coating solution on a base metal plate with a stabilized surface roughness.

[0072] The prepared coating solution is sprayed onto a base metal plate with a stabilized surface roughness using a mist spraying method to form a coating layer. The spraying amount can be appropriately controlled under spraying conditions that do not cause condensation of the sprayed particles during spraying. However, based on the amount of solution passing through the nozzle per unit time, it is advantageous to spray at a spraying amount of 10 to 500 mL / min per single nozzle.

[0073] The thickness of the coating layer to be formed on the base metal plate is controlled within a range of 10 to 500 μm, preferably 50 to 350 μm, and more preferably 100 to 200 μm, and can be adjusted in consideration of the target current amount and hydrogen generation amount of the electrode.

[0074] When using the coating solution according to the present invention, it has the advantage of being able to freely maintain the thickness of the coating layer during the coating process.

[0075] S6 - Step of heat-treating the base metal plate to obtain a plate having an impression graphite coating layer and forming it into an electrode.

[0076] After completing the coating of the previous step, a first heat treatment is performed at a temperature of 75 to 85°C for 30 to 60 minutes to volatilize the solvent component, and then a second heat treatment is performed at a temperature of 120 to 180°C for 20 to 60 minutes to completely form the coating (film) structure of the electrode.

[0077] In this step, the solvent in the coating solution can be completely volatilized at a relatively low temperature, and compared to the electrode manufacturing process using iridium (which requires several heat treatments at 600°C), heat curing can be completed at a relatively low temperature in a short period of time, so the electrode manufacturing process is simple, the heat energy used is low, and there is an advantage in that a coating layer of a desired thickness can be manufactured in a particularly short curing time.

[0078] After the heat treatment of the coating layer is completed, an electrode product having the desired specifications can be obtained through a process of forming the electrode into an appropriate size.

[0079] When an electrode for electrolysis is manufactured using the graphite particles and the coating solution containing the same according to the present invention as described above, a coating layer exhibiting the material properties (particularly, hydrophobicity and shape) of the graphite as well as the superhydrophobic properties of PVDF can be obtained. An electrode having such a coating layer exhibits distinct characteristics compared to conventional iridium electrodes.

[0080] Due to the nature of the electrode, which must be continuously operated in an electrolyte for electrolysis, it is inevitably exposed to electrochemical corrosion for a long period of time, and in such a situation, the possibility of corrosion and the actual corrosion degree increase depending on the degree of contact of the electrolyte with the electrode. In the case of the coating layer according to the present invention, graphite particles that are firmly bonded to a base metal with a surface slope (roughness) form a densely laminated structure, so that it is extremely difficult for electrolyte, bubbles, ions, etc. to penetrate, and since it has superhydrophobic properties, it prevents the penetration and adhesion of solutions or ionic components, and also exhibits excellent properties in preventing surface hydration, which is a phenomenon in which solutions wet the surface. Consequently, due to these superhydrophobic properties, more stable chemical resistance can be secured during the electrolysis process, and further, the lifespan of the electrode can be improved.

[0081] An electrode having a graphite coating layer obtainable by the manufacturing method according to the present invention may have a water molecule contact angle on a superhydrophobic surface of at least 150°, preferably at least 157°. This superhydrophobic characteristic can prevent oxygen and hydrogen bubbles generated on the electrode surface from sticking to the electrode surface in the form of bubbles. This is a very important characteristic for an electrolytic electrode. If bubbles stick to the electrode surface, a void is formed that causes an unsuitable gap (space), and the electrolyte cannot reach this void portion, preventing current from flowing. Consequently, this directly leads to a problem in that the electrode area is reduced (resistance increases due to this) by the amount of voids that are attached to the surface and cannot be discharged, which ultimately lowers the efficiency of producing the generated hydrogen. The surface of the superhydrophobic graphite coating layer according to the present invention not only provides low manufacturing cost and process convenience by resolving problems caused by voids, but also realizes both excellent electrochemical stability and ease of bubble discharge during operation, and is expected to have high utility in related industries.

[0082] The method for manufacturing a water electrolysis electrode according to the present invention is simpler than the existing iridium (IrO2) electrode manufacturing process, uses less heat energy, and can manufacture a coating layer of a desired thickness in a particularly short curing time, so it has high industrial applicability. In addition, the method for manufacturing a water electrolysis electrode according to the present invention has the advantages of being able to manufacture a water electrolysis electrode with relatively low equipment and manufacturing costs, and requiring less time, labor, and energy to perform the process steps. In addition, the water electrolysis electrode manufactured by the manufacturing method according to the present invention not only has the electrochemical stability and chemical resistance typically required, but also has the advantage of high bubble discharge efficiency generated during the actual hydrogen production process, and therefore is expected to have a high ripple effect in the hydrogen production-related industry.

Claims

1. A method for manufacturing a water electrolysis electrode having a graphite coating layer formed thereon, (1) A step of applying surface roughening processing to a base metal plate for manufacturing an electrode for electrolysis to provide surface roughness (roughness); (2) A step of stabilizing the surface roughness by applying the base metal plate with surface roughness to electrochemical corrosion treatment; (3) A step of mixing and stirring flake graphite and PVDF (polyvinylidene fluoride) to obtain size-controlled flake graphite particles; (4) A step of preparing a coating solution by adding the obtained size-adjusted impression graphite particles into an NMP (n-methyl-2-pyrrolidone) solution; (5) a step of forming a coating layer by spraying the manufactured coating solution on a base metal plate with a stabilized surface roughness; and (6) A step of applying heat to a plate on which a coating layer has been formed to obtain a plate having a heat-cured impression graphite coating layer, and then molding the plate, A method for manufacturing a water electrolysis electrode having a graphite coating layer formed thereon.

2. In claim 1, A method for manufacturing an electrode for electrolysis of water, wherein the base metal plate is formed with a graphite coating layer, characterized in that the base metal plate is made of a titanium (Ti), stainless steel (STS) and nickel (Ni) alloy material.

3. In claim 1, A method for manufacturing a water electrolysis electrode having a graphite coating layer formed thereon, characterized in that the surface roughness (roughness) in step (1) is formed to a depth of 2 to 20 ㎛, 5 to 18 ㎛, or 9 to 15 ㎛ based on the surface layer of the base metal plate.

4. In claim 1, A method for manufacturing a water electrolysis electrode having a graphite coating layer formed thereon, characterized in that in step (3), PVDF is mixed in an amount of 5 to 200 parts by weight, 50 to 150 parts by weight, or 90 to 130 parts by weight based on 100 parts by weight of graphite.

5. In claim 1, A method for manufacturing a water electrolysis electrode having an impression graphite coating layer formed thereon, characterized in that in step (4), the adjusted-size impression graphite particles are mixed in an NMP solvent to adjust the viscosity of the coating solution to a range of 10 to 500 cp, 50 to 350 cp, or 100 to 200 cp.

6. In claim 5, A method for manufacturing an electrode for electrolysis having a graphite coating layer formed thereon, characterized in that the viscosity is adjusted by mixing 80 to 120 parts by weight, 90 to 110 parts by weight, or 100 parts by weight of NMP based on 100 parts by weight of sized graphite particles.

7. In claim 1, A method for manufacturing an electrode for electrolysis having a graphite coating layer formed thereon, characterized in that in step (5), the coating liquid is sprayed at a spraying amount of 10 to 500 mL / min per single nozzle and coated on the surface of a base metal plate.

8. In claim 7, A method for manufacturing a water electrolysis electrode having a graphite coating layer formed thereon, characterized in that the thickness of the coating layer coated on the surface of a base metal plate is 10 to 500 ㎛, 50 to 350 ㎛, or 100 to 200 ㎛.

9. In claim 1, A method for manufacturing an electrode for electrolysis having a graphite coating layer formed thereon, characterized in that in step (6), heat curing is performed by performing a first heat treatment at a temperature of 75 to 85°C for 30 to 60 minutes to volatilize the solvent component, and then performing a second heat treatment at a temperature of 120 to 180°C for 20 to 60 minutes.

10. In claim 1, A method for manufacturing a water electrolysis electrode having a graphite coating layer formed thereon, characterized in that the surface of the water electrolysis electrode having a graphite coating layer formed thereon exhibits superhydrophobicity with a contact angle with water molecules of 150° or more.

11. An electrode for electrolysis of water having a coating layer formed thereon obtainable by the manufacturing method of any one of claims 1 to 10.

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