The Local Oxygen Transport Resistance of Ultra-Low Platinum Loading Cathode Catalyst Layer

Abstract

This study aims at the problem of the lower performance of membrane electrode assembly with the decrease in platinum loading in proton exchange membrane fuel cells. The local oxygen transport resistances of 30wt.%Pt/C catalyst layer and 60wt.%Pt/C carbon-doped dilution catalyst layers were calculated and compared by limiting the current density test. During this process, the total mass transfer resistance was replaced by pressure-independent oxygen transport resistance to eliminate the effect of pressure-dependent mass transfer resistance, thus, Knudsen diffusion resistances in the catalyst layer and microporous layer were considered. Results showed that 60wt.%Pt/C carbon-doped dilution catalyst layer exhibited higher bulk phase Knudsen diffusion resistance and local oxygen transport resistance than that of 30wt.%Pt/C catalyst layer, thereby, decreasing the performance at high current density. In addition, the reasons for lower performance were also analyzed.