Quantitative Analysis Effect of the Cathode Catalyst Layer with Various Ionomer Ratio on PEMFC by Protonic Resistance

Abstract

Cathode catalyst layer (CL) is responsible for main efficiency losses in polymer electrolyte membrane fuel cells because of both insufficient oxygen reduction kinetics and proton conduction losses. Quantitative analysis was used to study the impact of the ratio of ionomer/carbon on membrane electrode assemblies. The protonic impedance was estimated by electrochemical impedance spectroscopy (EIS) in the absence of oxygen using a physical impedance model. The performance of the prepared electrode was comprehensively evaluated by polarization curves, cyclic voltammetry, and EIS in different gas supply conditions (H2/air, H2/N2). Examining the data of EIS analysis and oxygen reduction reaction testing together, we inferred that the optimized ionomer/carbon ratio is the key role for effective reducing the ionic resistance and boosting mass transfer. The results verify the critical influence of ionomer ratio on the performances of cathode CL and could be used to fabricate an optimized cathode electrode.