PEMFC Performance Modeling Framework: Analyzing Pt Particle Size Distribution and Carbon Support Structure Impact

A cathode catalyst layer model framework that accounts for the position of the platinum particles on the carbon support structure is proposed. Combining a discrete platinum particle size distribution (PSD) with the binary classification of whether the platinum particle is decorated on the support surface (Pt<inf>outer</inf>) or buried inside the pore structure (Pt<inf>inner</inf>) allows the differentiation of distinct loss mechanisms. Additional mass transport and proton accessibility issues are modelled for Pt<inf>inner</inf> due to the extended diffusion path and worsened proton conduction inside the ionomer-free primary pores of the carbon support. Pt<inf>outer</inf> particles suffer from the adsorption of sulphonic acid groups (ionomer poisoning) and the densification of ionomer thin film that builds a compact layer above the outer Pt particle. The influence of carbon support type such as high and low surface area carbon on the cell performance is simulated and discussed for different scenarios. A parameter study is conducted that gives insight into the complex interaction between the contribution of current generation obtained from Pt<inf>inner</inf> and those from Pt<inf>outer</inf>. The impact on mass activity and mass transport resistance is analyzed as well. The effect of PSD evolution on the cell performance is discussed.