Optimizing catalyst layer structure design for improved water management of anion exchange membrane fuel cells

Recent research into anion exchange membrane fuel cells (AEMFCs) highlights challenges in achieving high performance, primarily due to poor water management. This study delves into how the structure and thickness of the catalyst layer, specifically the pore design, affect AEMFC efficiency. Our study reveals that H2/O2 AEMFC performance is significantly influenced by the distribution and structure of anode porous sizes, which affects water generation and transport kinetics. It has become evident that, instead of oxygen availability at the cathode, the primary factors constraining AEMFC performance are water supply through back-diffusion and water flooding at the anode. Notably, by controlling the carbon content of the anode catalyst layer to create gradient pores, we successfully alleviate mass transport limitations of gases in AEMFCs, while simultaneously improving water transport. Furthermore, insights from surface water transport and detailed phase field model analysis further confirmed that these gradient pores enhance water transportation rates. These results indicate that the fabrication of a porosity-gradient anode catalyst layer using carbon powder significantly increased the limit current density by 24 % (from 4.10 W cm−2 to 5.20 W cm−2) and the power density by 34.6 % (from 1.56 W cm−2 to 2.10 W cm−2), compared to the catalyst layer without carbon powder.