Enhancing water distribution in high-performance bipolar membrane fuel cells through optimized interface architecture

In bipolar membrane fuel cells (BPMFCs), water is an essential reactant to drive cathode half-cell reaction, making the optimization of water distribution in the cathode critical for enhancing overall performance. One promising strategy is to refine the junction interface architecture. Our research presents an innovative modification to the proton exchange membrane (PEM) and anion exchange membrane (AEM) interface microstructure, which reduces the distance for water transport to the cathode catalyst layer and maximizes the interfacial contact area. The increased interfacial contact area, with a normalized interfacial area (NIA) ranging from 1.00 to 1.65, correlates with a decrease in charge transfer impedance and a corresponding rise in oxygen reduction reaction (ORR) kinetics and peak power density. Significantly, the water distribution ratio at the cathode rose from 33.3 % in the unmodified BPMFC to 69.6 % with an NIA of 1.65. Consequently, the BPMFC with an NIA of 1.65 for the PEM|AEM interface achieved a peak power density of 1.037 W cm- 2, about 80 % higher than that of the unmodified interface. These results establish a link between the PEM|AEM interface structure, water distribution, and the fuel cell output performance, highlighting the importance of interface architecture in boosting BPMFCs' efficiency.