Effect of High Potential on Carbon Corrosion of Cathode Catalyst Layer in Proton Exchange Membrane Fuel Cells

The degradation of the catalyst layer is the main reason for the performance reduction of the proton exchange membrane fuel cells. The effects of high potential holding time, cell temperature, and relative humidity (RH) on carbon corrosion of cathode catalyst layer are studied in the present paper. The fuel cell was maintained at 1.4 V under three conditions (80 °C and 100% RH, 60 °C and 100% RH, 80 °C and 40% RH) and at different durations. The carbon corrosion rate was faster under high temperature and high RH. After high-potential holding test, the membrane electrode assembly (MEA) showed a decrease in performance, electrochemical active surface area (ECSA), and proton conduction resistance within the catalyst layer, as well as an increase in charge transfer resistance. After maintaining 1.4 V for 180 min, the ECSA retention rate of MEAs are only about 30%. The changes in the ECSA and the proton conduction impedance precede the performance degradation, which could more quickly reflect the degradation of carbon materials. Furthermore, this work investigated the evolution process of carbon corrosion under high potential based on duration and proposed a three-stage degradation mechanism of the cathode catalyst layer.