Dynamic modeling of Pt degradation and mitigation strategies in polymer electrolyte membrane fuel cells

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The durability issue of polymer electrolyte membrane fuel cells must be resolved before their widespread commercialization in transportation. A central issue in fuel cell durability is the loss of Pt electrochemical active surface area (ECSA) during automotive conditions, which is induced primarily by the Pt mass loss and Pt particle growth mechanisms. A comprehensive Pt degradation model to study the evolution of the ECSA distribution, induced mechanisms and mitigation strategies is developed. After validation with experimental results, the importance of the Pt mass loss and particle growth mechanisms is studied. Results reveal that the Pt mass loss mechanism occurs primarily near the proton-exchange-membrane/catalyst-layer (PEM/CL) interface and becomes more critical with improved electrode potential. The ECSA loss by the particle growth (Ostwald ripening) mechanism is, for the most part, uniformly distributed along the thickness direction, whereas it is suppressed near the PEM/CL interface by the Pt mass loss mechanism. The model also studies possible mitigation strategies for ECSA loss by suppressing the mass loss mechanism. Both the graded PEM structure and reduced Pt 2+ ion diffusivity can help mitigate the ECSA loss process. • Modeling of Pt degradation in the membrane electrode assembly is developed. • The model distinguishes Pt ECSA loss by mass loss and particle growth types. • Pt mass loss mechanism distributes nonuniformly and increases with cell voltage. • Pt growth mechanism distributes uniformly and increases with voltage cycling. • The model proposes mitigation strategies for ECSA loss by reducing Pt mass loss.