Study on high dispersion technology of bifunctional oxygen electrodes in proton exchange membrane unitized regenerative fuel cells
Proton exchange membrane unitized regenerative fuel cells(PEM-URFCs)are considered to be one of the most ideal energy storage devices.In PEM-URFCs,the processes carried out in a fuel cell and water electrolysis are integrated.Bifunctional oxygen electrodes(BOEs)constitute the core structure of the oxygen reduction reaction and that of the oxygen evolution reaction;this is facilitated by preparing a slurry of Pt and IrO2 materials.Since dispersing this catalyst slurry is difficult,this results in low catalyst utilization and poor durability.To overcome the above problems,in this study,the dispersion effect and stability of the Pt-IrO2 slurry were improved by combining the HS-PEG-COOH stabilizer with the interval ultrasonic dispersion process.Subsequently,the BOE was prepared by using this slurry.The experimental results show that the BOE prepared in this study is rich in nanoscale pores,and has a higher catalyst utilization rate and better round-trip efficiency(RTE)than the BOE prepared by the continuous ultrasonic dispersion process.The polarization performance test results show that the RTE of the PEM-URFC assembled by the BOE prepared in this study can reach up to 51.12%under the working condition of 0.5 A/cm²,which is 9%higher than that of reached by the PEM-URFC assembled by the BOE prepared by the continuous ultrasonic dispersion process.Additionally,after 3000 accelerated experiments,it was found that the RTE of the PEM-URFC assembled by the BOE prepared by this study decreased by only 0.249%,which was lower than that of the PEM-URFC assembled by the BOE prepared by the continuous ultrasonic dispersion process by 1.675%.Hence,the proposed method of combining the HS-PEG-COOH stabilizer and interval ultrasonic dispersion technology to improve the dispersion effect of the slurry used to prepare the BOE contributes to the existing knowledge regarding optimizing the preparation process of the BOE.
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