Methods and applications for evaluating the electrochemical active area of the anode using self-generated hydrogen in an electrolytic cell
Patent Information
- Application Number
- CN202310837169.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-07-10
- Publication Date
- 2026-09-01
- Estimated Expiration
- 2043-07-10
AI Technical Summary
然而该方法需要氢气源并需要在阴极口处设置进气管以及气体流量计，操作过于复杂，不适用于电解堆的实际应用
[0024] 1. The method of the present invention is simple and easy to implement, and does not require the addition or modification of equipment such as gas supply, flow control, gas heating and humidification for single electrolytic cells and electrolytic stacks.
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Figure CN116818876B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of water electrolysis, specifically relating to a method for evaluating the electrochemical active area of the anode using hydrogen produced by the electrolytic cell itself. Background Technology
[0002] Hydrogen is considered an ideal energy carrier for storing renewable energy. Water electrolysis, as a hydrogen production method, is considered a promising technology due to its advantages such as high hydrogen purity, fast load response time, small footprint, high efficiency, and the ability to couple with renewable energy sources. Currently, mainstream water electrolysis hydrogen production technologies can be divided into: alkaline water electrolysis (AWE), proton exchange membrane electrolysis (PEM), anion exchange membrane electrolysis (AEM), and solid oxide electrolysis (SOEC). Among these, proton exchange membrane electrolysis and anion exchange membrane electrolysis cells both include membrane electrode assemblies, which consist of an electrolyte membrane, a cathode catalyst, and an anode catalyst. These are key components that account for a large proportion of the cost of the electrolysis reactor. Therefore, improving the utilization rate of the anode and cathode catalysts and evaluating and characterizing the number of effective active sites in the catalyst layer are particularly important for reducing the cost of water electrolysis.
[0003] Currently, there are two main methods for evaluating the number of effective active sites in a catalyst layer: offline methods, such as BET surface area testing and mercury porosimetry, and online electrochemical testing methods, such as cyclic voltammetry and electrochemical impedance spectroscopy. Cyclic voltammetry is the most direct characterization method. The conventional cyclic voltammetry procedure involves: a platinum-carbon cathode catalyst layer; a specified flow rate of hydrogen gas as a reference electrode; and a nitrogen-saturated water anode as the working electrode to prevent interference from other gases and impurity ions. Then, an electrochemical workstation is used to apply a potential from the reference electrode to the working electrode for cyclic voltammetry testing. However, this method requires a hydrogen source and an inlet pipe and gas flow meter at the cathode inlet, making it overly complex and unsuitable for practical applications in electrolytic reactors. Therefore, developing a simple, easy-to-implement, and highly operable method for evaluating the electrochemical active area of water electrolysis catalysts is of great significance. Summary of the Invention
[0004] This invention provides a method for evaluating the electrochemical activity area of the anode using hydrogen produced by an electrolytic cell. The method involves a water electrolysis reaction occurring during constant current operation of the electrolytic cell, resulting in the generation of a certain amount of hydrogen at the cathode. The constant current operation is then stopped, and the hydrogen outlet valve at the cathode is closed, allowing the hydrogen to remain on the cathode side as a reference electrode. After water replacement in the circulating water system, the anode becomes the working electrode. An electrochemical workstation can then perform cyclic voltammetry, AC impedance, and other tests on the anode using the cathode, thereby evaluating the electrochemical activity area of the anode in a single electrolytic cell and an electrolytic stack. The method employed in this invention is simple, easy to implement, highly operable, and feasible for evaluation.
[0005] The present invention adopts the following technical solution: an electrolytic cell testing device, comprising an electrolytic cell, a water circulation system, an electrochemical workstation, a power supply system, a hydrogen storage system, a protective gas, and a water replenishment system, characterized in that: the hydrogen storage system and the protective gas are connected to the electrolytic cell via valves 1 and 2 respectively; a pressure gauge is installed on the supply pipeline of the hydrogen storage system to display the hydrogen pressure in real time; the inlet and outlet of the electrolytic cell are connected to the water circulation system via valves 4 and 3 respectively; the water replenishment system supplies water to the water circulation system; the power supply system is connected to the cathode and anode of the electrolytic cell to perform constant current water electrolysis to produce hydrogen; the electrochemical workstation is electrically connected to the cathode and anode of the electrolytic cell to perform electrochemical testing.
[0006] Based on the above-mentioned apparatus, the present invention also discloses a method for evaluating the electrochemical active area of the anode using self-generated hydrogen in an electrolytic cell, characterized in that:
[0007] Step 1: Water electrolysis occurs through constant current operation in the electrolytic cell, producing a certain amount of hydrogen at the cathode and oxygen at the anode.
[0008] Step 2: Stop the constant current operation and close the cathode hydrogen outlet valve to leave hydrogen gas in the cathode.
[0009] Step 3: The water circulation system is drained and replenished multiple times to replace the anode circulating water;
[0010] Step 4: Using the cathode as a reference electrode, perform electrochemical tests on the anode to obtain the anodic electrochemical active area of each cell in the single electrolytic cell and the electrolytic stack.
[0011] Preferably, step 2 further includes the following: closing the hydrogen outlet valve to ensure that hydrogen is retained at the cathode, and then maintaining the hydrogen pressure within a certain range and keeping the pressure conditions unchanged.
[0012] Preferably, step 3 further includes the following: maintaining the operating water temperature of the electrolytic cell, and performing multiple water changes in the anode water circulation system to reduce the impact of dissolved oxygen in the water generated in step 1.
[0013] Preferably, step 4 further includes the following: using an electrochemical workstation to perform electrochemical tests on each cell of the electrolytic reactor, and connecting the anode and cathode of each cell respectively.
[0014] Preferably, during constant current operation, the current density is 0.2-1 A / cm². -2 The running time is 5-30 minutes.
[0015] Preferably, the hydrogen pressure range is 100-120 kPa.
[0016] Preferably, the water in the water circulation system is deionized water that does not contain oxygen or impurities, and the water is changed 2-5 times.
[0017] Preferably, the electrochemical testing methods include: cyclic voltammetry, linear sweep potential testing, or AC impedance testing.
[0018] The preferred method is: Cyclic voltammetry test: using an electrochemical workstation, with the cathode as the reference electrode, the anode is subjected to potential cycling, the potential cycling range is 0.4-1.4V, the potential scan rate is 20mV / s, positive scan, and the number of cycles is generally 3-5 times. The integral charge q* under the entire window is obtained by measuring the curve to measure the electrochemical active area of the anode.
[0019] The preferred method is: linear potential scan test: using an electrochemical workstation, with the cathode as the reference electrode, a potential line scan is performed on the anode. The potential scan range is 0-1.4V, the potential scan rate is 20mV / s, and it is a positive scan. The obtained curves can be compared with the size of the oxidation peak of the anode catalyst layer to roughly evaluate the electrochemical active area of the anode.
[0020] Preferably, the following method is used: AC impedance testing: using an electrochemical workstation with the cathode as the reference electrode, a constant potential impedance test is performed on the anode. The potential range is 0.9-1.4V, the frequency range is 100000Hz-0.1Hz, and the amplitude is 10-50mV. The measured curves can be used to obtain the ohmic resistance and proton conduction resistance of the electrolytic cell, which can indirectly evaluate the electrochemical active area of the anode.
[0021] The present invention also discloses an application of the above method in evaluating the electrochemical active area of proton exchange membrane electrolysis and anion exchange membrane electrolysis of water.
[0022] Preferred application scenarios: based on the electrochemical active area of each individual cell in a single electrolytic cell and an electrolytic stack.
[0023] Compared with the prior art, the present invention has the following advantages:
[0024] 1. The method of the present invention is simple and easy to implement, and does not require the addition or modification of equipment such as gas supply, flow control, gas heating and humidification for single electrolytic cells and electrolytic stacks.
[0025] 2. It is feasible to apply it in scenarios such as evaluating the anodic electrochemical active area of proton exchange membrane electrolysis and anion exchange membrane electrolysis of water.
[0026] 3. It is feasible to apply it in scenarios such as evaluating the electrochemical active area of the anode in single electrolytic cells and electrolytic stacks. Attached Figure Description
[0027] Figure 1 This is a diagram of the electrolytic cell testing equipment applicable to the present invention in Example 1.
[0028] Figure 2These are the cyclic voltammetry curves obtained in Example 1, comparing the evaluation method of the present invention with the conventional evaluation method. Detailed Implementation
[0029] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention is described with reference to the following specific embodiments, but the invention is by no means limited to these examples.
[0030] Example 1
[0031] See Figure 1 As shown. An electrolytic cell testing device includes an electrolytic cell, a water circulation system, an electrochemical workstation, a power supply system, a hydrogen storage system, a protective gas system, and a water replenishment system. Its features include: the hydrogen storage system and the protective gas system are connected to the electrolytic cell via valves 1 and 2, respectively; a pressure gauge is installed on the hydrogen storage system's supply pipeline to display the hydrogen pressure in real time; the inlet and outlet of the electrolytic cell are connected to the water circulation system via valves 4 and 3, respectively; the water replenishment system supplies water to the water circulation system; the power supply system is connected to the cathode and anode of the electrolytic cell for constant current water electrolysis to produce hydrogen; and the electrochemical workstation is electrically connected to the cathode and anode of the electrolytic cell for electrochemical testing.
[0032] Example 2
[0033] A method for evaluating the electrochemical active area of an anode using self-generated hydrogen in an electrolytic cell, characterized in that:
[0034] Step 1: Water electrolysis occurs through constant current operation in the electrolytic cell, generating a certain amount of hydrogen gas at the cathode;
[0035] Step 2: Stop the constant current operation and close the cathode hydrogen outlet valve to leave the hydrogen gas in the cathode, and replace the water at the anode through the water circulation system;
[0036] Step 3: Using the cathode as a reference electrode, perform electrochemical tests on the anode to obtain the anodic electrochemical active area of each cell in the single electrolytic cell and the electrolytic stack.
[0037] The active area of the single electrolytic cell fixture used in this embodiment of the invention is 25 cm². 2 It consists of a flow collector, flow field plate, PTFE gasket, end plate, and fasteners. The cathode bipolar plate is a graphite plate, and the anode bipolar plate is a titanium plate, with a single serpentine flow field on it. The test was conducted at a 25cm depth. 2 The Pt loading in the cathode catalyst layer of the membrane electrode assembly is 0.8 mg / cm³. -2 The iridium oxide loading in the anode catalyst layer is 2 mg / cm³. -2The proton exchange membrane was Nafion 115 (127 μm). The electrolysis test conditions were: single electrolysis cell temperature 60℃, anode pump water flow rate 20 L / h. The cyclic voltammetry test conditions were: potential window 0.4–1.4 V; potential scan rate 20 mV / s; electrochemical active area was measured by the integrated charge q* over the entire window.
[0038] Example 3:
[0039] See Figure 2 As shown. The testing method of this invention: First, the electrolytic cell is operated at a constant current using a power supply system, with a current density of 1 A / cm². -2 After running for 5 minutes, the power system was shut off, stopping the constant current operation of the electrolytic cell. Simultaneously, hydrogen outlet valve 1 was closed to maintain the hydrogen pressure at atmospheric pressure. The single electrolytic cell maintained its water temperature, and the anode-side water circulation system was replenished with deionized water free of oxygen and other impurities. At this point, using the cathode as the reference electrode and the anode as the working electrode, cyclic voltammetry was performed on the single electrolytic cell using an electrochemical workstation. Calculations from the cyclic voltammetry curves showed that the integrated charge q* of iridium oxide at the anode of this single electrolytic cell, obtained using the method of this invention, was 932.76 mC / cm². -2 .
[0040] Standard testing method: The circulating water on the anode side of the single electrolytic cell is deionized water free of oxygen and other impurities. On the cathode side, hydrogen gas is introduced through the inlet using a hydrogen cylinder as the gas source, with the flow rate controlled by mass flow rate and set to 100 sccm. Using the cathode as the reference electrode and the anode as the working electrode, cyclic voltammetry testing of the single electrolytic cell is performed using an electrochemical workstation. Calculations from the cyclic voltammetry curves show that the integrated charge q* of iridium oxide at the anode of this single electrolytic cell, obtained using standard methods, is 924.92 mC / cm². -2 .
[0041] The results show that the calculation of the anodic electrochemical active area using the present invention is consistent with the results of conventional methods, and the test device does not require hydrogen cylinders, mass flow meters, and cathode gas lines, indicating that the present invention is simple and easy to implement and is suitable for evaluating the anodic electrochemical active area of a single electrolytic cell.
[0042] Example 4
[0043] This invention employs a method for evaluating the electrochemical active area of the anode using hydrogen produced by the electrolytic cell, and applies this method to scenarios involving the evaluation of the electrochemical active area of proton exchange membrane (PEM) and anion exchange membrane (EEM) water electrolysis. In particular, this invention is applied to scenarios involving the electrochemical active area of individual cells within a single electrolytic cell and an electrolytic stack.
[0044] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.
Claims
1. A method for evaluating the electrochemical active area of an anode using self-generated hydrogen in an electrolytic cell, the method being based on an electrolytic cell testing device, the electrolytic cell testing device comprising an electrolytic cell, a water circulation system, an electrochemical workstation, a power supply system, a hydrogen storage system, a protective gas system, and a water replenishment system; the hydrogen storage system and the protective gas system are connected to the electrolytic cell via valves 1 and 2, respectively; a pressure gauge is installed on the supply pipeline of the hydrogen storage system to display the hydrogen pressure in real time; the inlet and outlet of the electrolytic cell are connected to the water circulation system via valves 4 and 3, respectively; the water replenishment system supplies water to the water circulation system; the power supply system is connected to the cathode and anode of the electrolytic cell to perform constant current water electrolysis to produce hydrogen; the electrochemical workstation is electrically connected to the cathode and anode in the electrolytic cell to perform electrochemical testing; characterized in that: Step 1: Water electrolysis occurs through constant current operation in an electrolytic cell, producing a certain amount of hydrogen at the cathode and oxygen at the anode; during constant current operation, the current density is 0.2-1 A / cm². -2 The running time is 5-30 minutes; Step 2: Stop the constant current operation and close the cathode hydrogen outlet valve to leave the hydrogen in the cathode; close the hydrogen outlet valve to ensure that the hydrogen remains in the cathode. Then, the hydrogen pressure needs to be maintained within a certain range and the pressure conditions should be kept constant. Step 3: The water circulation system is drained and replenished multiple times to replace the anode circulating water; the water in the water circulation system is deionized water that does not contain oxygen impurities, and the water is replaced 2-5 times; the electrolytic cell maintains the operating water temperature, and the anode water circulation system is replaced multiple times to reduce the impact of dissolved oxygen in the water generated in Step 1. Step 4: Using the cathode as a reference electrode, perform electrochemical tests on the anode to obtain the anode electrochemical active area of each cell in the single electrolytic cell and the electrolytic stack; use an electrochemical workstation to perform electrochemical tests on each cell in the electrolytic stack, and connect the anode and cathode of each cell respectively; The hydrogen pressure range is 100-120 kPa; Electrochemical testing methods include: cyclic voltammetry, linear scan potential testing, or AC impedance testing.
2. The method for evaluating the electrochemical activity area of an anode using self-generated hydrogen in an electrolytic cell according to claim 1, characterized in that: Cyclic voltammetry test: Using an electrochemical workstation, with the cathode as the reference electrode, the anode is subjected to potential cycling. The potential cycling range is 0.4-1.4V, the potential scan rate is 20mV / s, positive scan, and the number of cycles is generally 3-5. The integral charge q under the entire window is obtained by measuring the curve to measure the electrochemical active area of the anode.
3. The method for evaluating the electrochemical activity area of the anode using self-generated hydrogen in an electrolytic cell according to claim 1, characterized in that: Linear scanning potential test: Using an electrochemical workstation, with the cathode as the reference electrode, a potential linear scan was performed on the anode. The potential scan range was 0-1.4V, the potential scan rate was 20mV / s, and it was a positive scan. The obtained curves can be compared with the size of the oxidation peak of the anode catalyst layer to roughly evaluate the electrochemical active area of the anode.
4. The method for evaluating the electrochemical activity area of an anode using self-generated hydrogen in an electrolytic cell according to claim 1, characterized in that: AC impedance testing: Using an electrochemical workstation with the cathode as the reference electrode, constant potential impedance testing was performed on the anode. The potential range was 0.9-1.4V, the frequency range was 100000Hz-0.1Hz, and the amplitude was 10-50mV. The measured curves can be used to obtain the ohmic resistance and proton conduction resistance of the electrolytic cell, which can indirectly evaluate the electrochemical active area of the anode.
5. The application of the method described in claim 1 in evaluating the electrochemical active area of proton exchange membrane electrolysis and anion exchange membrane electrolysis of water.