The effect of catalyst layer design on catalyst utilization in PEMFC studied via stochastic reconstruction method

Catalyst utilization is an important determinant of proton exchange membrane fuel cell performance, and increasing the catalyst utilization is one of the most critical approaches to reducing the catalyst loading in PEMFC. 4-phase stochastic reconstruction method based on the variable-resolution Quartet Structure Generation Set (QSGS) algorithm is utilized to elucidate the influence of different parameters of electrode preparation, including the porosity, the dispersion degree of carbon agglomerate, ionomer content, and carbon support size, on the catalyst utilization in the catalyst layer. It was found that there exist optimal values for the porosity, dispersion degree of carbon agglomerate, ionomer content, and carbon support sizes in CLs and any deviations from these optimal values would lead to transport issues of electron, proton and mass within CLs. Taking electron, proton and mass transport into consideration simultaneously, the optimal Pt utilization is 46.55% among 48 cases in this investigation, taken at the carbon support diameter of 40 nm, the porosity of 0.4, the agglomerate spatial density of 25 mu m- 3 and I/C at 0.7. The selection of porosity, ultrasonic dispersion technique and ionomer content for conventional electrode preparation requires compromises on mass, electron and proton transport, leading to catalyst utilization in CLs hardly exceeding 50%. Therefore, the next generation of catalyst layer design and preparation technology is desired.