High-performance direct hydroboron fuel cell membrane electrode and preparation method thereof
By using anion exchange membrane and cation exchange membrane solutions as binders in direct borohydride fuel cells, the catalyst layer was optimized, solving the problems of fuel permeation and mixing potential, and achieving high-performance and stable electrochemical reactions.
Patent Information
- Application Number
- CN202510878698.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-27
- Publication Date
- 2025-11-11
AI Technical Summary
Existing direct borohydride fuel cells (DBFCs) perform worse than traditional proton exchange membrane fuel cells, mainly due to the low potassium/sodium ion conductivity of the cation exchange membrane, which leads to fuel permeation and mixing potential problems, affecting power density.
Anion exchange membranes and cation exchange membrane solutions are used as binders to optimize the composition of the catalyst layer. The cation exchange resin in the cathode catalyst layer and the anion exchange membrane solution in the anode catalyst layer are used to improve ionic conductivity and reduce fuel permeation.
It improves the performance and durability of direct borohydride fuel cells, exhibiting excellent electrochemical performance and high power density, and stable cycle performance.
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Figure CN120933407A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of fuel cell technology, specifically relating to a high-performance direct borohydride fuel cell membrane electrode and its preparation method. Background Technology
[0002] Fuel cells have attracted increasing attention due to their advantages such as high energy conversion efficiency and low environmental pollution. In particular, proton exchange membrane fuel cells (PEMFCs) have garnered significant attention in recent years due to their broad application prospects in automotive power and other fields. However, because hydrogen storage, transportation, and supply still face some insurmountable difficulties, researchers are attempting to develop direct liquid fuel cells using electrochemically active solution- or liquid hydrogen-rich compounds as fuel. Direct borohydride fuel cells (DBFCs) are a representative example of such direct liquid fuel cells. DBFCs directly use an alkaline solution of borohydride as the anode fuel, typically sodium borohydride or potassium borohydride. Borohydrides (KBH4, NaBH4, etc.) are compounds with a very high hydrogen content, exhibiting a higher specific capacity by weight than metal hydrides and a higher specific capacity by volume than compressed hydrogen and liquid hydrogen. For example, sodium borohydride contains 10.6 wt% hydrogen. Boron hydrides are easily oxidized by catalysts such as Pt, Ru, Pd, and Ni. The complete oxidation of each mole of borohydride releases 8 electrons, resulting in a theoretical anode voltage of -1.24 V. However, researchers have devoted considerable effort to catalyst research and commonly use cation exchange membranes to separate the anode and cathode, maximally preventing liquid fuel from permeating to the cathode and causing a mixed potential, thus reducing fuel cell performance. However, the potassium / sodium ion conductivity of cation exchange membranes is much lower than that of protons; therefore, the reported performance of DBFCs is currently inferior to that of traditional proton exchange membrane fuel cells. Improving the power density is a necessary prerequisite for the commercial application of DBFCs. Summary of the Invention
[0003] To address or partially address the problems existing in related technologies, this invention provides a high-performance direct borohydride fuel cell membrane electrode and its preparation method.
[0004] This invention provides a high-performance direct borohydride fuel cell membrane electrode, comprising an anion exchange membrane, an anode catalyst layer located at the anode of the anion exchange membrane, and a cathode catalyst layer located at the cathode of the anion exchange membrane, wherein the binder of the cathode catalyst layer is a cation exchange membrane solution, and the binder of the anode catalyst layer is an anion exchange membrane solution or a cation exchange membrane solution.
[0005] Preferably, the main chain of the anion exchange membrane is polyphenylene ether, polyarylether sulfone, polyarylether ketone, polyolefin, polybenzimidazole, or pure aromatic polymer; the side chain functional groups are quaternary ammonium compounds, guanidine salts, or imidazole compounds.
[0006] More preferably, the anion exchange membrane is an Alkymer. ® Anion exchange membrane.
[0007] Preferably, the cation exchange membrane solution is a solution of perfluorosulfonic acid, partially fluorinated, or sulfonated aromatic ionomers.
[0008] More preferably, the cation exchange membrane solution is Nafion. ® membrane solution.
[0009] Preferably, the anode catalyst in the anode catalyst layer is a noble metal or noble metal alloy catalyst; the cathode catalyst in the cathode catalyst layer is a noble metal, noble metal alloy, perovskite, or transition metal alloy.
[0010] A method for preparing a high-performance direct borohydride fuel cell membrane electrode includes the following steps: (1) Immerse the anion exchange membrane in potassium hydroxide solution for a period of time, then take it out and rinse it with water until neutral to obtain the treated anion exchange membrane; (2) After mixing isopropanol with the cathode catalyst, the cathode catalyst suspension is obtained by sonication under ice bath conditions; then, cation exchange membrane solution is added to the cathode catalyst suspension and the cathode catalyst slurry is obtained by sonication under ice bath conditions. (3) After mixing isopropanol with the anode catalyst, the anode catalyst suspension is obtained by ultrasonication under ice bath conditions; then, cation exchange membrane solution or anion exchange membrane solution is added to the anode catalyst suspension, and the anode catalyst slurry is obtained by ultrasonication under ice bath conditions. (4) The cathode catalyst slurry is evenly sprayed onto carbon paper to obtain a cathode catalyst layer; (5) The anode catalyst slurry is evenly sprayed onto the carbon cloth to obtain the anode catalyst layer; (6) The membrane electrode was obtained by overlapping the anode catalyst layer, the treated anion exchange membrane, and the cathode catalyst layer in that order.
[0011] Preferably, in step (1), the concentration of the potassium hydroxide solution is 2M, the temperature is 60℃, and the time is 12h.
[0012] Preferably, in step (2), isopropanol and cathode catalyst are reacted at a ratio of 3-6 mg / mL. -1 The concentration of the cathode catalyst is mixed.
[0013] Preferably, in step (3), isopropanol and the anode catalyst are reacted at a ratio of 3-6 mg / mL. -1 The concentration of the anode catalyst is mixed.
[0014] Preferably, in step (2), the mass of the cation exchange membrane in the cation exchange membrane solution is 20-40% of the mass of the cathode catalyst.
[0015] Preferably, in step (3), the mass of the cation exchange membrane in the cation exchange membrane solution or the anion exchange membrane in the anion exchange membrane solution is 20-40% of the mass of the anode catalyst.
[0016] Preferably, the loading of the cathode catalyst in the cathode catalyst layer is 1.5-3.0 mg cm⁻¹. -2 The loading of noble metals in the anode catalyst layer is 0.1-0.5 mg cm⁻¹. -2 .
[0017] The technical solution provided by this invention can include the following beneficial effects: The membrane electrode assembly obtained by optimizing the catalyst layer binder and ion exchange membrane exhibits excellent electrochemical performance in an O2-NaBH4 fuel cell. Thanks to the higher ionic conductivity of the anion exchange membrane and the cation exchange resin in the cathode catalyst layer, the BH4 permeates into the cathode... - The amount of [something] is greatly reduced, thus effectively improving the performance and durability of DBFC. Attached Figure Description
[0018] Figure 1 The graphs show the polarization curves of the membrane electrodes prepared in Examples 1-4 and their corresponding power density versus current density. The horizontal axis represents current density, in mA / cm². -2 The left vertical axis represents voltage in volts (V), and the right vertical axis represents power density in mW / cm². -2 .
[0019] Figure 2 The graphs show the polarization curves of the membrane electrodes prepared in Example 1 and Comparative Examples 1-3, as well as the corresponding power density versus current density graphs. The horizontal axis represents current density, in mA / cm². -2 The left vertical axis represents voltage in volts (V), and the right vertical axis represents power density in mW / cm². -2 .
[0020] Figure 3 The graph shows the cycling performance under Example 1. The horizontal axis represents the cycling performance test duration in hours (h), and the vertical axis represents the voltage in volts (V). Detailed Implementation
[0021] The preparation steps of the Mn-Co spinel catalyst in the examples and comparative examples are as follows: (a) Take 1 g of BLACK PEARLS ® 2000 conductive carbon black was placed in a 500 mL single-necked flask, 200 mL of 6M nitric acid was added, and the mixture was heated at 80°C under reflux for 6 h. Finally, it was washed by centrifugation with deionized water and vacuum dried in an oven at 80°C for 12 h to obtain the acidified carbon support.
[0022] (ii) Disperse 60 mg of the acidified carbon support prepared in step (i) and 63.5 mg of cobalt acetate tetrahydrate in a 100 mL conical flask, add 30 mL of deionized water, and sonicate for 15 min.
[0023] (iii) Place the conical flask in a water bath and start heating. While stirring with a magnetic force, slowly add 0.5 mL of ammonia water. After the temperature reaches 60°C, slowly add 62.5 mg of manganese acetate tetrahydrate and keep warm for 2 h.
[0024] (iv) The solution obtained in step (iii) is sonicated for 10 min, poured into the lining of a polytetrafluoroethylene hydrothermal reactor, and placed in an oven at 150°C for hydrothermal reaction for 3 h.
[0025] (v) The hydrothermal reaction product in step (iv) was washed by centrifugation with deionized water, and the collected solid was then freeze-dried for 12 h to obtain the Mn-Co spinel catalyst.
[0026] Example 1 A method for preparing a high-performance direct borohydride fuel cell membrane electrode includes the following steps: (1) Alkymer ® The anion exchange membrane was placed in 300 mL of 2 M potassium hydroxide solution and then placed in an oven at 60 °C for 12 h. After that, the anion exchange membrane was rinsed with deionized water until the pH of the deionized water became 7, thus obtaining the treated anion exchange membrane.
[0027] (2) Pour 30 mg of a commercial Pt / C catalyst with a noble metal content of 40 wt.% into a 10 mL sample vial, add 6 mL of isopropanol, and ultrasonically disperse in an ice bath for 30 min. The resulting slurry is denoted as solution A. Then weigh 200 mg of 5 wt% Nafion. ® The (cation exchange resin) membrane solution was added dropwise to solution A, and ultrasonic dispersion was continued in an ice bath for 30 min. The resulting slurry was denoted as solution B.
[0028] (3) Dry the carbon cloth on a heating table at 80°C for 30 min, then pour solution B into a spray gun and evenly spray the catalyst onto the middle of the carbon cloth to obtain the anode catalyst layer, controlling the noble metal loading to be 0.15 mg. Pt cm -2 .
[0029] (4) Pour 30 mg of Mn-Co spinel catalyst into a 10 mL sample vial, add 6 mL of isopropanol, and ultrasonically disperse in an ice bath for 30 min. The resulting slurry is denoted as solution C. Then weigh 200 mg of 5 wt% Nafion. ® The (cation exchange resin) membrane solution was added dropwise to solution C, and ultrasonic dispersion was continued in an ice bath for 30 min. The resulting slurry was denoted as solution D.
[0030] (5) Dry the carbon paper on a heating table at 80°C for 30 min, then pour solution D into a spray gun and evenly spray the catalyst onto the middle of the carbon paper to obtain a cathode catalyst layer, controlling the catalyst loading to be 1.5 mg cm⁻¹. -2 .
[0031] (6) The membrane electrode was obtained by overlapping the anode catalyst layer, the treated anion exchange membrane, and the cathode catalyst layer in that order, and was denoted as Pt / C-CoMn, C / A / C.
[0032] Example 2 A method for preparing a high-performance direct borohydride fuel cell membrane electrode includes the following steps: (1) Alkymer ® The anion exchange membrane was placed in 300 mL of 2 M potassium hydroxide solution and then placed in an oven at 60 °C for 12 h. After that, the anion exchange membrane was rinsed with deionized water until the pH of the deionized water became 7, thus obtaining the treated anion exchange membrane.
[0033] (2) Pour 30 mg of a commercial Pt / C catalyst with a noble metal content of 40 wt.% into a 20 mL sample vial, add 10 mL of isopropanol, and ultrasonically disperse in an ice bath for 30 min. The resulting slurry is denoted as solution A. Then weigh 120 mg of 5 wt% Nafion. ® The (cation exchange resin) membrane solution was added dropwise to solution A, and ultrasonic dispersion was continued in an ice bath for 30 min. The resulting slurry was denoted as solution B.
[0034] (3) Dry the carbon cloth on a heating table at 80°C for 30 min, then pour solution B into a spray gun and evenly spray the catalyst onto the middle of the carbon cloth to obtain the anode catalyst layer, controlling the noble metal loading to be 0.5 mg. Pt cm -2.
[0035] (4) Pour 30 mg of a commercial Pt / C catalyst with a noble metal content of 40 wt.% into a 10 mL sample vial, add 5 mL of isopropanol, and ultrasonically disperse in an ice bath for 30 min. The resulting slurry is denoted as solution C. Then weigh 240 mg of 5 wt% Nafion. ® The (cation exchange resin) membrane solution was added dropwise to solution C, and ultrasonic dispersion was continued in an ice bath for 30 min. The resulting slurry was denoted as solution D.
[0036] (5) Dry the carbon paper on a heating table at 80°C for 30 min, then pour solution D into a spray gun and evenly spray the catalyst onto the middle of the carbon paper to obtain a cathode catalyst layer, controlling the catalyst loading to be 3.0 mg cm⁻¹. -2 .
[0037] (6) The membrane electrode was obtained by overlapping the anode catalyst layer, the treated anion exchange membrane, and the cathode catalyst layer in that order, and was denoted as Pt / C-Pt / C, C / A / C.
[0038] Example 3 A method for preparing a high-performance direct borohydride fuel cell membrane electrode includes the following steps: (1) Alkymer ® Anion exchange membrane placed in 300 mL 2 M mL -1 The anion exchange membrane was placed in a potassium hydroxide solution and then placed in an oven at 60°C for 12 hours. After that, it was rinsed with deionized water until the pH of the deionized water became 7, thus obtaining the treated anion exchange membrane.
[0039] (2) Pour 30 mg of a commercial Pt / C catalyst with a noble metal content of 40 wt.% into a 10 mL sample vial, add 5 mL of isopropanol, and ultrasonically disperse in an ice bath for 30 min. The resulting slurry is denoted as solution A. Then weigh 240 mg of 5 wt% Alkymer. ® The (anion exchange resin) membrane solution was added dropwise to solution A, and ultrasonic dispersion was continued in an ice bath for 30 min. The resulting slurry was denoted as solution B.
[0040] (3) Dry the carbon cloth on a heating table at 80°C for 30 min, then pour solution B into a spray gun and evenly spray the catalyst onto the middle of the carbon cloth to obtain the anode catalyst layer, controlling the noble metal loading to be 0.1 mg. Pt cm -2 .
[0041] (4) Pour 30 mg of Mn-Co spinel catalyst into a 20 mL sample vial, add 10 mL of isopropanol, and ultrasonically disperse in an ice bath for 30 min. The resulting slurry is denoted as solution C. Then weigh 120 mg of 5 wt% Nafion. ® The (cation exchange resin) membrane solution was added dropwise to solution C, and ultrasonic dispersion was continued in an ice bath for 30 min. The resulting slurry was denoted as solution D.
[0042] (5) Dry the carbon paper on a heating table at 80°C for 30 min, then pour solution D into a spray gun and evenly spray the catalyst onto the middle of the carbon paper to obtain a cathode catalyst layer, controlling the catalyst loading to be 2.0 mg cm⁻¹. -2 .
[0043] (6) The membrane electrode was obtained by overlapping the anode catalyst layer, the treated anion exchange membrane, and the cathode catalyst layer in that order, and was denoted as Pt / C-CoMn, A / A / C.
[0044] Example 4 A method for preparing a high-performance direct borohydride fuel cell membrane electrode includes the following steps: (1) Alkymer ® The anion exchange membrane was placed in 300 mL of 2 M potassium hydroxide solution and then placed in an oven at 60 °C for 12 h. After that, the anion exchange membrane was rinsed with deionized water until the pH of the deionized water became 7, thus obtaining the treated anion exchange membrane.
[0045] (2) 30 mg of a commercial PtIr / C catalyst with a noble metal content of 40 wt.% was poured into a 10 mL sample vial, 6 mL of isopropanol was added, and the mixture was ultrasonically dispersed in an ice bath for 30 min. The resulting slurry was designated as solution A. Then, 200 mg of 5 wt% Nafion was weighed. ® The (cation exchange resin) membrane solution was added dropwise to solution A, and ultrasonic dispersion was continued in an ice bath for 30 min. The resulting slurry was denoted as solution B.
[0046] (3) Dry the carbon cloth on a heating table at 80°C for 30 min, then pour solution B into a spray gun and evenly spray the catalyst onto the middle of the carbon cloth to obtain the anode catalyst layer, controlling the noble metal loading to be 0.15 mg. Pt cm -2 .
[0047] (4) Pour 30 mg of Mn-Co spinel catalyst into a 10 mL sample vial, add 6 mL of isopropanol, and ultrasonically disperse in an ice bath for 30 min. The resulting slurry is denoted as solution C. Then weigh 200 mg of 5 wt% Nafion.® The (cation exchange resin) membrane solution was added dropwise to solution C, and ultrasonic dispersion was continued in an ice bath for 30 min. The resulting slurry was denoted as solution D.
[0048] (5) Dry the carbon paper on a heating table at 80 °C for 30 min, then pour solution D into a spray gun and evenly spray the catalyst onto the middle of the carbon paper to obtain a cathode catalyst layer, controlling the catalyst loading to be 1.5 mg cm⁻¹. -2 .
[0049] (6) The membrane electrode was obtained by overlapping the anode catalyst layer, the treated anion exchange membrane, and the cathode catalyst layer in that order, and was denoted as PtIr / C-CoMn, C / A / C.
[0050] Comparative Example 1 A method for preparing a high-performance direct borohydride fuel cell membrane electrode includes the following steps: (1) Pour 30 mg of a commercial Pt / C catalyst with a noble metal content of 40 wt.% into a 10 mL sample vial, add 6 mL of isopropanol, and ultrasonically disperse in an ice bath for 30 min. The resulting slurry is denoted as solution A. Then weigh 200 mg of 5 wt% Nafion. ® The (cation exchange resin) membrane solution was added dropwise to solution A, and ultrasonic dispersion was continued in an ice bath for 30 min. The resulting slurry was denoted as solution B.
[0051] (2) Dry the carbon cloth on a heating table at 80°C for 30 min, then pour solution B into a spray gun and evenly spray the catalyst onto the middle of the carbon cloth to obtain the anode catalyst layer, controlling the noble metal loading to be 0.15 mg. Pt cm -2 .
[0052] (3) Pour 30 mg of Mn-Co spinel catalyst into a 10 mL sample vial, add 6 mL of isopropanol, and ultrasonically disperse in an ice bath for 30 min. The resulting slurry is denoted as solution C. Then weigh 200 mg of 5 wt% Nafion. ® The (cation exchange resin) membrane solution was added dropwise to solution C, and ultrasonic dispersion was continued in an ice bath for 30 min. The resulting slurry was denoted as solution D.
[0053] (4) Dry the carbon paper on a heating table at 80°C for 30 min, then pour solution D into a spray gun and evenly spray the catalyst onto the middle of the carbon paper to obtain a cathode catalyst layer, controlling the catalyst loading to be 1.5 mg cm⁻¹. -2 .
[0054] (5) According to the anode catalyst layer, Nafion ®The membrane electrode, denoted as Pt / C-CoMn, C / C / C, is formed by sequentially overlapping the cation exchange membrane and the cathode catalyst layer.
[0055] Comparative Example 2 A method for preparing a high-performance direct borohydride fuel cell membrane electrode includes the following steps: (1) Alkymer ® Anion exchange membrane placed in 300 mL 2 M mL -1 The anion exchange membrane was placed in a potassium hydroxide solution and then placed in an oven at 60°C for 12 hours. After that, it was rinsed with deionized water until the pH of the deionized water became 7, thus obtaining the treated anion exchange membrane.
[0056] (2) Pour 30 mg of a commercial Pt / C catalyst with a noble metal content of 40 wt.% into a 10 mL sample vial, add 6 mL of isopropanol, and ultrasonically disperse in an ice bath for 30 min. The resulting slurry is denoted as solution A. Then weigh 200 mg of 5 wt% Nafion. ® The (cation exchange resin) membrane solution was added dropwise to solution A, and ultrasonic dispersion was continued in an ice bath for 30 min. The resulting slurry was denoted as solution B.
[0057] (3) Dry the carbon cloth on a heating table at 80°C for 30 min, then pour solution B into a spray gun and evenly spray the catalyst onto the middle of the carbon cloth to obtain the anode catalyst layer, controlling the noble metal loading to be 0.15 mg. Pt cm -2 .
[0058] (4) Pour 30 mg of Mn-Co spinel catalyst into a 10 mL sample vial, add 6 mL of isopropanol, and ultrasonically disperse in an ice bath for 30 min. The resulting slurry is denoted as solution C. Then weigh 200 mg of 5 wt% Alkymer. ® The (anion exchange resin) membrane solution was added dropwise to solution C, and ultrasonic dispersion was continued in an ice bath for 30 min. The resulting slurry was denoted as solution D.
[0059] (5) Dry the carbon paper on a heating table at 80°C for 30 min, then pour solution D into a spray gun and evenly spray the catalyst onto the middle of the carbon paper to obtain a cathode catalyst layer, controlling the catalyst loading to be 1.5 mg cm⁻¹. -2 .
[0060] (6) The membrane electrode was obtained by overlapping the anode catalyst layer, the treated anion exchange membrane, and the cathode catalyst layer in that order, and was denoted as Pt / C-CoMn, C / A / A.
[0061] Comparative Example 3 A method for preparing a high-performance direct borohydride fuel cell membrane electrode includes the following steps: (1) Alkymer ® Anion exchange membrane placed in 300 mL 2 M mL -1 The anion exchange membrane was placed in a potassium hydroxide solution and then placed in an oven at 60°C for 12 hours. After that, it was rinsed with deionized water until the pH of the deionized water became 7, thus obtaining the treated anion exchange membrane.
[0062] (2) Pour 30 mg of a commercial Pt / C catalyst with a noble metal content of 40 wt.% into a 10 mL sample vial, add 6 mL of isopropanol, and ultrasonically disperse in an ice bath for 30 min. The resulting slurry is denoted as solution A. Then weigh 200 mg of 5 wt% Alkymer. ® The (anion exchange resin) membrane solution was added dropwise to solution A, and ultrasonic dispersion was continued in an ice bath for 30 min. The resulting slurry was denoted as solution B.
[0063] (3) Dry the carbon cloth on a heating table at 80 °C for 30 min, then pour solution B into a spray gun and evenly spray the catalyst onto the middle of the carbon cloth to obtain the anode catalyst layer, controlling the noble metal loading to be 0.15 mg. Pt cm -2 .
[0064] (4) Pour 30 mg of Mn-Co spinel catalyst into a 10 mL sample vial, add 6 mL of isopropanol, and ultrasonically disperse in an ice bath for 30 min. The resulting slurry is denoted as solution C. Then weigh 200 mg of 5 wt% Alkymer. ® The (anion exchange resin) membrane solution was added dropwise to solution C, and ultrasonic dispersion was continued in an ice bath for 30 min. The resulting slurry was denoted as solution D.
[0065] (5) Dry the carbon paper on a heating table at 80 °C for 30 min, then pour solution D into a spray gun and evenly spray the catalyst onto the middle of the carbon paper to obtain a cathode catalyst layer, controlling the catalyst loading to be 1.5 mg cm⁻¹. -2 .
[0066] (6) The membrane electrode was obtained by overlapping the anode catalyst layer, the treated anion exchange membrane, and the cathode catalyst layer in that order, and was denoted as Pt / C-CoMn, A / A / A.
[0067] Example of effect In the examples and comparative examples, the specific operating steps and test parameters for using the prepared membrane electrode in single-cell assembly and testing are as follows: (i) The back of the carbon paper of the membrane electrode contacts the graphite plate with a single serpentine flow channel, and the back of the carbon cloth of the membrane electrode contacts the graphite plate with a double serpentine flow channel. The size of the graphite plate is 1.5 cm × 1.5 cm. The anode and cathode use 0.3 mm high-temperature resistant silicone rubber as sealing gaskets, and the clamping force of the fixture is 6 N·m.
[0068] (ii) During the test, the cathode gas O2 temperature was 80℃, the humidity was 80%, and the flow rate was 0.5 nlpm. The anode fuel composition was 1 M KOH + 3 M NaBH4. The temperature was maintained at 80℃, and the flow rate was 5 mL min. -1 .
[0069] Figure 1 The figures show the polarization curves of the membrane electrodes prepared in Examples 1-4 and their corresponding power density versus current density. It can be seen that when a cation exchange resin is used as a binder in the cathode catalyst layer and an anion exchange membrane is used as the separator, the voltage does not decrease rapidly with increasing current density, thus exhibiting a maximum of approximately 1.5 W / cm². -2 The power density.
[0070] Figure 2 The graphs shown are polarization curves and corresponding power density versus current density graphs of the membrane electrodes prepared in Examples 1 and Comparative Examples 1-3. It can be seen that when anion exchange resin is used as a binder in the cathode catalyst layer, the open-circuit voltage is significantly reduced, and the polarization phenomenon is more severe. This is due to the presence of BH4 in the anode fuel. - Fuel permeation can easily pass through the anion exchange membrane and the anion exchange resin in the catalyst layer. This severe fuel permeation can also lead to a mixed potential, thus affecting battery performance. However, when a cation exchange membrane is used as the separator, K... + Or Na + Its conductivity is lower than that of OH - The conductivity in high-performance commercial anion exchange membranes is low, resulting in poor performance.
[0071] Figure 3 The graph shows the cycling performance under Example 1, at 500 mA cm⁻¹. -2 Under a constant current density, the voltage retention rate was approximately 96.2% after about 10 hours, demonstrating excellent stability.
[0072] The membrane electrodes prepared in Comparative Examples 1-3 were tested at 500 mA cm⁻¹. -2 Time polarization is quite severe.
[0073] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.
Claims
1. A high-performance direct borohydride fuel cell membrane electrode, characterized in that: It includes an anion exchange membrane, an anode catalyst layer located at the anode of the anion exchange membrane, and a cathode catalyst layer located at the cathode of the anion exchange membrane, wherein the binder of the cathode catalyst layer is a cation exchange membrane solution, and the binder of the anode catalyst layer is either anion exchange membrane solution or a cation exchange membrane solution.
2. The high-performance direct borohydride fuel cell membrane electrode according to claim 1, characterized in that: The main chain of the anion exchange membrane is polyphenylene ether, polyarylether sulfone, polyarylether ketone, polyolefin, polybenzimidazole or pure aromatic polymer, and the side chain functional groups are quaternary ammonium, guanidine salt or imidazole; the cation exchange membrane is a perfluorosulfonic acid, partially fluorinated or sulfonated aromatic ionomer.
3. The high-performance direct borohydride fuel cell membrane electrode according to claim 1, characterized in that: The anode catalyst in the anode catalyst layer is a noble metal or noble metal alloy catalyst; the cathode catalyst in the cathode catalyst layer is a noble metal, noble metal alloy, perovskite or transition metal alloy.
4. The method for preparing the high-performance direct borohydride fuel cell membrane electrode according to any one of claims 1-3, characterized in that: Includes the following steps: (1) Immerse the anion exchange membrane in potassium hydroxide solution for a period of time, then take it out and rinse it with water until neutral to obtain the treated anion exchange membrane; (2) After mixing isopropanol with the cathode catalyst, the cathode catalyst suspension is obtained by sonication under ice bath conditions; then, cation exchange membrane solution is added to the cathode catalyst suspension and the cathode catalyst slurry is obtained by sonication under ice bath conditions. (3) After mixing isopropanol with the anode catalyst, the anode catalyst suspension is obtained by ultrasonication under ice bath conditions; then, cation exchange membrane solution or anion exchange membrane solution is added to the anode catalyst suspension, and the anode catalyst slurry is obtained by ultrasonication under ice bath conditions. (4) The cathode catalyst slurry is evenly sprayed onto carbon paper to obtain a cathode catalyst layer; (5) The anode catalyst slurry is evenly sprayed onto the carbon cloth to obtain the anode catalyst layer; (6) The membrane electrode was obtained by overlapping the anode catalyst layer, the treated anion exchange membrane, and the cathode catalyst layer in that order.
5. The method for preparing the high-performance direct borohydride fuel cell membrane electrode according to claim 4, characterized in that: In step (1), the concentration of potassium hydroxide solution is 2 mol / L, the temperature is 60℃, and the time is 12h.
6. The method for preparing the high-performance direct borohydride fuel cell membrane electrode according to claim 4, characterized in that: In step (2), isopropanol and the cathode catalyst are reacted at a ratio of 3-6 mg / mL. -1 The concentration of the cathode catalyst is mixed.
7. The method for preparing the high-performance direct borohydride fuel cell membrane electrode according to claim 4, characterized in that: In step (3), isopropanol and the anode catalyst are reacted at a ratio of 3-6 mg / mL. -1 The concentration of the anode catalyst is mixed.
8. The method for preparing the high-performance direct borohydride fuel cell membrane electrode according to claim 4, characterized in that: In step (2), the mass of the cation exchange membrane in the cation exchange membrane solution is 20-40% of the mass of the cathode catalyst.
9. The method for preparing the high-performance direct borohydride fuel cell membrane electrode according to claim 4, characterized in that: In step (3), the mass of the cation exchange membrane in the cation exchange membrane solution or the anion exchange membrane in the anion exchange membrane solution is 20-40% of the mass of the anode catalyst.
10. The method for preparing the high-performance direct borohydride fuel cell membrane electrode according to claim 4, characterized in that: The loading of the cathode catalyst in the cathode catalyst layer is 1.5-3 mg cm⁻¹. -2 The loading of noble metals in the anode catalyst layer is 0.1-0.5 mg cm⁻¹. -2 .