Degradation behavior of proton exchange membrane fuel cells under hydrogen starvation in freezing conditions

Proton exchange membrane fuel cells suffer from cell reversal due to hydrogen starvation, which can be exacerbated by hydrogen channel blockage after extensive ice formation under freezing conditions. The cell reversal degradation of conventional anodes and reversal-tolerant anodes (RTAs) at sub-zero temperature (−30 °C to −5 °C) is investigated. During freezing cell reversal, a water electrolysis plateau is observed with a low reversal voltage, but the typical subsequent carbon corrosion plateau usually observed at above-zero temperature is absent. Reversal tests indicate that the reversal time of RTAs at freezing temperature is significantly shorter than that at above-zero temperature. Local water starvation can occur in freezing cell reversal, as evidenced by the consistent changing trend of the reversal voltage and internal resistance because of the reduced water diffusion capacity in the proton exchange membrane. The 300 min accumulated long-term cyclic freezing reversal of RTAs reveals a low degradation rate. The suppression of the sub-zero temperature on the oxidation of the carbon support and the platinum–carbon catalyst and the influence of the water content in the catalyst layer on cell reversal explain the low degradation rate in freezing cell reversal.