Particle size distribution degradation model for PEM fuel cell Pt/C catalyst based on population balance equation

Electrochemically active surface area (ECSA) loss is the main cause of proton exchange membrane fuel cell performance degradation. It involves interactions between kinetics of Pt particle size distribution (PSD) and several degradation mechanisms, including particle dissolution, redeposition, coagulation and detachment from carbon support. A population balance equation was established to relate the PSD evolutions with the loss of ECSA. Dimensionless Damko<spacing diaeresis>hler numbers (Dardp, Dacgl, Dadet) were defined to characterize the relative magnitudes between different degradation rates. Systematic studies revealed the dimensionless transition criterions form dissolution limit to other degradation modes. Sensitivity analysis indicated the redisposition rate and dissolution rate were the two most influential parameters. The initial parameters, rather than the initial function type of the unimodal distribution, is the dominating factors for PSD degradation process. This study provides theoretical foundation for optimization of catalyst layer design and durability.