Method for regenerating water electrolysis anode
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- HYDROXPAND INC
- Filing Date
- 2025-08-05
- Publication Date
- 2026-07-30
Smart Images
Figure KR2025011726_30072026_PF_FP_ABST
Abstract
Description
Regeneration method for the anode of water electrolysis
[0001] Cross-citation with related applications
[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2025-0008742 dated January 21, 2025, the entire contents of which are incorporated herein.
[0003] Technology field
[0004] The present invention relates to a method for regenerating a water electrolysis anode.
[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 suffer from a problem where voltage rises and efficiency decreases during operation due to corrosion of the anode surface and degradation of the electrolyte. This performance degradation acts as a major cause of shortened lifespan of the electrolytic anode and reduced energy efficiency. Therefore, there is a need for a method to reactivate the electrolytic anode without replacing it.
[0009] The present invention aims to provide a method for regenerating a water electrolysis anode that restores the performance of a water electrolysis anode whose performance has deteriorated as the voltage increases by more than 10% based on the initial voltage.
[0010] [1] According to one embodiment of the present invention, a method for regenerating a water electrolysis anode is provided, comprising the steps of: preparing a water electrolysis anode with a voltage increased by 10% or more based on an initial voltage (S1); preparing an electrolyte by mixing a Ni precursor and an Fe precursor with an electrolyte solution (S2); and reactivating the water electrolysis anode with a voltage increased by 10% or more based on an initial voltage by applying an electrical load (S3).
[0011] [2] In the above [1], the Ni precursor and the Fe precursor can be mixed at a molar concentration of 0.01 mM to 100 mM based on the electrolyte.
[0012] [3] In the above [1] or [2], 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.
[0013] [4] In at least one of [1] to [3] above, the Fe precursor may be at least one selected from the group consisting of FeCl2, FeCl3, Fe(acac)2 and Fe(NO3)3.
[0014] [5] In at least one of [1] to [4] above, the molar ratio of Ni and Fe in the electrolyte may be 5.5 : 4.5 to 9.5 : 0.5.
[0015] [6] In at least one of [1] to [5] 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.
[0016] [7] In at least one of [1] to [6] above, the molar concentration of the electrolyte solution may be 0.01M to 1M.
[0017] [8] In at least one of [1] to [7] above, the (S2) step may be performed by further mixing at least one selected from the group consisting of Co precursor, Bi precursor and W precursor.
[0018] [9] In at least one of [1] to [8] above, the step (S3) may be to feed the electrolyte to the degraded water electrolysis anode at a rate of 0.3 L / min to 35 L / min.
[0019]
[0010] In at least one of [1] to [9] above, the step (S3) can be performed for 0.5 to 10 hours.
[0020]
[0011] In at least one of [1] to
[0010] above, the step (S3) 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 regenerating a water electrolysis anode according to the present invention involves introducing an electrolyte containing a metal precursor into a water electrolysis anode whose performance has deteriorated and whose voltage has increased by more than 10% based on the initial voltage, and simultaneously applying an electrical load to activate it, thereby immediately initiating an electrochemical reaction, so that current density, voltage, and ohmic resistance can be restored.
[0023] Figure 1 is a graph showing the current density according to the applied voltage (0V to 2.0V) measured by linear sweep voltammetry (LSV) of the water electrolysis anodes regenerated according to Examples 1 to 4 and Comparative Examples 1 to 4.
[0024] Figure 2 is a Scanning Electron Microscope (SEM) image of a water electrolysis anode regenerated according to Example 1.
[0025] The present invention will be described in detail below.
[0026] 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.
[0027] 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.
[0028]
[0029] The method for regenerating a water electrolysis anode according to the present invention comprises the steps of: preparing a water electrolysis anode in which the voltage is increased by 10% or more based on the initial voltage (S1); preparing an electrolyte by mixing a Ni precursor and an Fe precursor with an electrolyte solution (S2); and reactivating the electrolyte by introducing it into the water electrolysis anode in which the voltage is increased by 10% or more based on the initial voltage and applying an electrical load (S3).
[0030] The inventors discovered that the performance of the water electrolysis anode can be restored and regenerated through a combination of the three processes described above, and completed the present invention.
[0031]
[0032] Hereinafter, each step of the method for regenerating a water electrolysis anode according to one embodiment of the present invention will be described in detail.
[0033]
[0034] (S1) Step
[0035] In one aspect, the above step (S1) is a process of preparing a water electrolysis anode in which the voltage is increased by more than 10% based on the initial voltage.
[0036] For example, if a water electrolysis anode is operated at a constant current for more than 2,000 hours, the operating voltage increases relative to the initial voltage due to degradation. Specifically, as electrochemical reactions proceed for a long time and oxidation reactions occur, the catalyst surface of the anode becomes excessively oxidized, reducing reactivity. Additionally, corrosion of the interface between the catalyst layer and the substrate reduces the attractive force between the substrate and the catalyst layer, which can lead to the detachment of the catalyst layer. Furthermore, there is a problem in that Ni ions and Fe ions leached from the anode react with the basic electrolyte to form precipitates, which block the porous transport layer or the micropores of the anode, thereby hindering mass transfer and increasing overvoltage.
[0037] In the present invention, a state in which the voltage increases by 10% or more relative to the initial voltage is defined as an indicator indicating that the performance of the water electrolysis anode has deteriorated. This can be measured by comparing the initial voltage and the operating voltage of the water electrolysis anode. Specifically, (1) when the water electrolysis anode is operating normally, the operating voltage measured under a specified current density is defined as the initial voltage, and (2) after driving the water electrolysis anode for a certain period of time, the operating voltage is measured after setting it to operate at the same current density as when the initial voltage was measured. (3) Afterward, [(operating voltage – initial voltage) / (initial voltage)] × 100 is calculated, and if the voltage increases by 10% or more relative to the initial voltage, the performance of the water electrolysis anode is evaluated as deteriorated.
[0038] As described above, when the voltage increases by more than 10% relative to the initial voltage, it requires higher energy to generate the same current, which reduces energy efficiency. Additionally, it oxidizes the surface of the anode or increases the leaching of metal ions, damaging the structure of the anode and lowering ion conductivity. Consequently, the performance of the anode deteriorates, leading to the problem of having to replace the water electrolysis anode.
[0039]
[0040] (S2) Step
[0041] In one aspect, the above step (S2) is a process of preparing an electrolyte by mixing a Ni precursor and an Fe precursor with an electrolyte solution.
[0042] As described above, in the case of a water electrolysis anode in which the voltage has increased by more than 10% based on the initial voltage, there is a problem in that impurities accumulate in the electrolyte and the concentration is non-uniform, causing a decrease in ion conductivity. Accordingly, it is necessary to replace the electrolyte in the water electrolysis anode whose performance has deteriorated while introducing the electrolyte.
[0043] Generally, the electrolyte can effectively transmit current within the water electrolysis anode and OH, which can promote the formation of a hydroxide catalyst layer. - To provide ions, it includes a basic solution such as KOH and does not include separate catalyst particles. However, according to one embodiment of the present invention, since catalyst raw materials such as Ni precursors and Fe precursors are separately mixed into the electrolyte solution, when an electric load is applied while the electrolyte is subsequently introduced into the water electrolysis anode, the Ni ions and Fe ions contained in the electrolyte are electrodeposited on the substrate of the water electrolysis anode 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 a part close to the anode, thereby promoting the oxygen evolution reaction of the water electrolysis anode.
[0044] At this time, the substrate of the above-mentioned water electrolysis anode may be at least one selected from the group consisting of Ni, Fe, Ni-Fe alloy and stainless steel (Stainless steel, SUS).
[0045] 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.
[0046] 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.
[0047] 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.
[0048] 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 the OOH phase reduces the activation energy of the oxygen evolution reaction, which can improve the performance of the water electrolysis anode.
[0049] 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.
[0050] 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.
[0051] The above step (S2) 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.
[0052] The electrolyte prepared as described above is introduced into a water electrolysis anode in which the voltage has increased by more than 10% relative to the initial voltage. The Ni and Fe ions contained in the electrolyte restore the damaged catalyst layer on the anode surface, thereby increasing the oxygen generation reaction rate. Additionally, by replacing the existing electrolyte containing solid precipitates and improving mass transfer in the porous transport layer and the anode, the operating voltage is restored to the initial voltage, thereby improving energy efficiency. Consequently, the durability of the water electrolysis anode is improved, the replacement cycle is extended, and there is no need to replace it with a new water electrolysis anode, which offers excellent cost-effectiveness.
[0053]
[0054] (S3) Step
[0055] In one aspect, the above step (S3) is a process of introducing the electrolyte into a water electrolysis anode in which the voltage has been increased by more than 10% based on the initial voltage and reactivating it by applying an electrical load.
[0056] Conventionally, since the water electrolysis anode is activated without applying an electrical load separately after the electrolyte is introduced, the time for the Fe precursor to penetrate and react on the surface of the Ni oxide is prolonged, and consequently, the anode surface is not evenly activated and reacts only partially, resulting in a problem of reduced uniformity in the performance of the water electrolysis anode.
[0057] On the other hand, the present invention allows for the reactivation time of the water electrolysis anode to be shortened by introducing an electrolyte and simultaneously applying an electric load, thereby forming a catalyst layer on the anode and initiating an electrochemical reaction from the moment the electrolyte is introduced. Furthermore, by circulating the electrolyte at a high speed while simultaneously applying the electric load to evenly distribute the electrolyte over a large area of the electrode, the electrolyte penetrates uniformly into the micropores or surface of the anode, thereby activating the electrochemical reaction and allowing the performance of the water electrolysis anode to be restored to an excellent level.
[0058] In the above step (S3), the electrolyte may be introduced into the water electrolysis anode, in which the voltage has been increased by 10% or more, at a rate of 0.3 L / min to 35 L / min, preferably 10 L / min to 30 L / min, more preferably 15 L / min to 25 L / min. When the above range is satisfied, impurities or inactive layers on the surface of the anode are removed, and as the electrolyte passes through the inside of the water electrolysis anode, contact with the anode becomes uniform, so that the performance of the water electrolysis anode can be restored to an excellent level.
[0059] The above step (S3) can be performed for 0.5 to 10 hours, preferably 0.5 to 5 hours, more preferably 0.5 to 1.5 hours. When the above range is satisfied, the electrolyte containing Ni ions and Fe ions can form a new active catalyst layer, and the electrolyte can flow with a uniform concentration distribution, so that the performance of the water electrolysis anode can be restored to an excellent level.
[0060] The above step (S3) 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 anode 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.
[0061] Specifically, when a water electrolysis anode is reactivated with a voltage increased by more than 10% based on the initial voltage using the above-mentioned chronopotentiometry, the oxide layer or impurities present on the anode surface are removed and a high-performance catalyst layer is re-formed, thereby increasing the initial current density.
[0062] 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, the inert oxide layer on the anode surface is converted into a catalyst layer with high activity in the oxygen evolution reaction, and the reduction in the performance of the catalyst layer due to excessive oxidation can be prevented. In addition, the porous structure of the catalyst layer grows, increasing the contact area with the electrolyte, and the electrolyte is evenly distributed on the anode surface, thereby promoting the activation of the anode.
[0063]
[0064] As described above, the present invention allows the initial density, voltage, and ohmic resistance of a water electrolysis anode to be restored to their state before operation by applying an electrical load and introducing an electrolyte solution, in which a Ni precursor and an Fe precursor are mixed with an electrolyte solution, into a water electrolysis anode with degraded performance and the voltage has increased by more than 10% based on the initial voltage.
[0065]
[0066] The present invention will be explained in more detail below through specific embodiments.
[0067] 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.
[0068]
[0069] Examples and Comparative Examples
[0070] Example 1
[0071] (1) Preparation stage of a water electrolysis anode with degraded performance
[0072] 0.6A / cm 2 Under current density conditions, an electrolytic anode was prepared in which the initial voltage per cell was 1.8V, but the voltage increased to 2.1V after operating for 2507 hours.
[0073]
[0074] (2) Electrolyte preparation step
[0075] 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.
[0076]
[0077] (3) Reactivation stage
[0078] The electrolyte is injected into the above-mentioned degraded water electrolysis anode at a rate of 20 L / min, and simultaneously, 0.6 A / cm² is injected for 1 hour until the potential reaches 1.8 V using chronopotentiometry. 2 The above-mentioned degraded water electrolysis anode was reactivated by applying current under current density conditions.
[0079]
[0080] Example 2
[0081] In the above (2) electrolyte preparation step, NiCl2 and FeCl2 were mixed such that the molar ratio of Ni:Fe was 4:6, except that the water electrolysis anode was regenerated in the same way as in Example 1.
[0082]
[0083] Example 3
[0084] In the above (2) electrolyte preparation step, the water electrolysis anode was regenerated in the same way as in Example 1, except that a 1.2M concentration KOH solution was used.
[0085]
[0086] Example 4
[0087] In the above (3) reactivation step, 3 A / cm² for 1 hour until the potential becomes 1.8 V using chronopotentiometry 2 The water electrolysis anode was regenerated in the same manner as in Example 1, except that current was applied under current density conditions.
[0088]
[0089] Comparative Example 1
[0090] Without performing the (2) electrolyte preparation step and (3) reactivation step of Example 1 above, operate for more than 2000 hours to 0.6 A / cm 2 A water electrolysis anode with degraded performance was prepared, in which the voltage per cell increased by 0.3V under current density conditions.
[0091]
[0092] Comparative Example 2
[0093] In the above (2) electrolyte preparation step, the water electrolysis anode was regenerated in the same way as in Example 1, except that FeCl2 was not mixed and NiCl2 was mixed at a molar concentration of 1 mM.
[0094]
[0095] Comparative Example 3
[0096] In the above (2) electrolyte preparation step, the water electrolysis anode was regenerated in the same way as in Example 1, except that NiCl2 was not mixed and FeCl2 was mixed at a molar concentration of 5 mM.
[0097]
[0098] Comparative Example 4
[0099] In the above (3) reactivation step, the electrolytic anode was reactivated in the same way as in Example 1, except that the electrolyte was introduced into the electrolytic anode with degraded performance and then reactivated without applying an electrical load.
[0100]
[0101] Experimental Example: Performance Evaluation of Water Electrolysis Anode
[0102] (1) Voltage evaluation
[0103] For the water electrolysis anodes according to Examples 1 to 4 and Comparative Examples 1 to 4, the voltage was varied from an initial potential (0V) to 2V at a constant scanning speed of 10 mV / s using Linear Sweep Volutammetry (LSV), and the corresponding current density was measured.
[0104] At this time, 0.6 A / cm 2 If the voltage per cell is 1.8V or less, the performance of the water electrolysis anode is evaluated as excellent, and the results are shown in Table 1 and Figure 1 below.
[0105]
[0106] Voltage [V] Example 11.68 Example 21.72 Example 31.71 Example 41.73 Comparative Example 12.00 Comparative Example 21.90 Comparative Example 31.89 Comparative Example 41.92
[0107] Referring to Table 1 above, it can be seen that the electrolytic anodes regenerated according to Examples 1 to 4 have lower voltage per cell compared to the electrolytic anodes regenerated according to Comparative Examples 1 to 4, and thus have superior performance.
[0108]
Claims
1. A step (S1) of preparing a water electrolysis anode in which the voltage has increased by more than 10% based on the initial voltage; A step (S2) of preparing an electrolyte by mixing Ni precursors and Fe precursors with an electrolyte solution; and A method for regenerating a water electrolysis anode comprising the step (S3) of introducing the above electrolyte into a water electrolysis anode in which the voltage has increased by 10% or more based on the above initial voltage and applying an electrical load to reactivate it.
2. In Claim 1, A method for regenerating a water electrolysis anode 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.
3. In Claim 1, A method for regenerating a water electrolysis anode 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.
4. In Claim 1, A method for regenerating a water electrolysis anode 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.
5. In Claim 1, A method for regenerating a water electrolysis anode in which the molar ratio of Ni and Fe in the above electrolyte is 5.5 : 4.5 to 9.5 : 0.
5.
6. In Claim 1, A method for regenerating a water electrolysis anode 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.
7. In Claim 1, A method for regenerating a water electrolysis anode in which the molar concentration of the above electrolyte solution is 0.01M to 1M.
8. In Claim 1, The above step (S2) is a method for regenerating a water electrolysis anode by further mixing at least one selected from the group consisting of a Co precursor, a Bi precursor, and a W precursor.
9. In Claim 1, The above step (S3) is a method for regenerating a water electrolysis anode, wherein the electrolyte is introduced into the deteriorated water electrolysis anode at a rate of 0.3 L / min to 35 L / min.
10. In Claim 1, The above step (S3) is a method for regenerating a water electrolysis anode performed for 0.5 to 10 hours.
11. In Claim 1, The above step (S3) is a method for regenerating a water electrolysis anode, 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 anode performed under current density conditions.