LAUSR

Abstract Engineering low-Pt membrane electrode assembly without sacrificing performance is essential to accelerate the commercialization of proton exchange membrane fuel cells (PEMFCs). The increased oxygen transport resistance, however, limits the performance improvement in the low-Pt fuel cell. Herein, a cross-dimensional agglomerate model (1-2D model) focusing on oxygen transport behaviors is proposed and developed by coupling a 1-D oxygen transport sub-model with a 2-D two-phase multicomponent PEMFC sub-model. The oxygen dissolution, adsorption and diffusion from gas pore to active sites in cathode catalyst layer (CCL) are considered in the 1-D sub-model. With the aid of the developed 1-2D model, the oxygen transport characteristics under different structural parameters and operation conditions are analyzed. It is found that the oxygen transport resistance in cathode backing layer (CBL-OTR) is larger than the OTR in cathode microporous layer (CMPL-OTR), and both are much higher than the OTR in the gas pores of the CCL (bulk OTR). When changing the structural parameters and operation conditions, the CBL-OTR, CMPL-OTR, and the bulk OTR remain almost unchanged. While, the OTR in the CCL that is caused by the oxygen transport penetrating through ionomer film from water film to active sites (local OTR) is markedly varied. The local OTR possesses a largest contribution to the total OTR, which is more than 50%. When Pt loading goes to 0.1 mg cm−2, the ratios of the CBL-OTR, the CMPL-OTR, the bulk OTR, and the local OTR are respectively 20%, 18%, 7%, and 55%. If reducing Pt loading to 0.05 mg cm−2, the local OTR takes over 72% of the total OTR. Moreover, based on the understanding of oxygen transport behaviors, the PEMFC with an optimized CCL shows a high peak power density, even better than that with a 1.2 mgPt cm−2 original CCL, saving the 91% Pt loading. This work provides a deep insight into oxygen transport behaviors and offers an effective way to construct a high-performance ultra-low-Pt fuel cell.