Effects of Microporous Layer on PBI-based Proton Exchange Membrane Fuel Cell Performance

摘要

This study investigates the influence of microporous layer (MPL) on the performance of a high- temperature proton exchange membrane fuel cell utilizing a phosphoric-acid-doped polybenzimidazole(PBI) electrolyte. The effects of MPL compositions including polytetrafluorethylene (PTFE) andcarbon black are considered. Under the same catalyst loading, phosphoric acid doping level, andoperation conditions, the fuel cell performance is measured to evaluate the importance of MPL anddetermine the optimal PTFE content and carbon loading. The method of electrochemical impedancespectroscopy is employed to characterize the variations in the ohmic resistance and polarization losseswithin the cell. The results show that both the PTFE content and carbon loading in the MPL may affectthe cell performance significantly. The MPL with a PTFE content of 40 wt% and carbon loading of 1.0-2 mg cm is found to give the optimal cell performance.