Insight into the potential strategies for mitigating Pt degradation in proton exchange membrane fuel cells (PEMFCs): From the perspective of Pt ion transport

Abstract

To explore the potential strategies for mitigating catalyst degradation from the perspective of Pt ion transport, here we employ a mathematical method to investigate the effects of the position of Pt band and Pt ion diffusivity in the membrane on Pt degradation under H2 | Air conditions. Results show that promoting the Pt band away from the cathode and lowering the Pt ion diffusivity are both efficient to mitigate the total electrochemical surface area (ECSA) loss and obtain a more uniform distribution of ECSA and Pt mass after cycling, so that greatly improve the fuel cell durability. Meanwhile, an inversive transport of Pt ions from membrane to the cathode is revealed during the cathodic sweep, when the Pt band is ≥ 8 μm away from the cathode or the Pt ion diffusivity of the membrane is ≤0.4 times normal. Moreover, the limit values of mitigated ECSA loss are evaluated, which are predicted to reach about 20.8% and 10.1% by moving the Pt band toward the anode and suppressing the Pt ion diffusivity in the membrane, respectively. Accordingly, several possible strategies for mitigating Pt degradation are discussed and two main solutions are finally concluded.