Catalyst layer design with inhomogeneous distribution of platinum and ionomer optimal for proton exchange membrane fuel cell cold-start

Performance of proton exchange membrane fuel cells under subfreezing environments is restrained by the properties of electrode materials, for instance, the platinum and ionomer loadings. Herein, we pro-pose an optimization strategy for the cold-start performance based on comprehensive multiphysics sim-ulation, employing a functional inhomogeneous cathode catalyst layer (CL) with appropriate platinum and ionomer loading gradients. Numerical analysis reveals the interaction modes between spatial evolu-tion of ice deposition and local species transport in CLs during cold start. As a result, increased loadings towards the membrane side of the CL and near the cathode outlet improve the cold-start performance by promoting the ice uniformity and uplifting the critical ice fractions at the failure time. A practically rel-evant, multilayer graded cathode CL has been optimally designed, which proves to significantly expand the feasible operation domains of cold start while benefiting the nominal working cell performance com-pared with homogeneous CLs.(c) 2022 Elsevier Ltd. All rights reserved.