Optimizing interlayer thickness for enhanced performance and chemical durability in sandwich-structured PEM fuel cells

Polymer electrolyte membrane (PEM) fuel cells are a leading technology for clean energy conversion, but their widespread adoption is hindered by the trade-off between high performance and long-term chemical durability. Here, we report an engineered multilayer PEM that sandwiches a gas barrier interlayer between cast Nafion outer layers. A blend of poly(vinyl alcohol) and poly(vinylsulfonic acid) (PVA/PVS) is used as the interlayer material, designed to suppress gas crossover and mitigate chemical attack without sacrificing ionic conductivity. The optimized membrane (designated PVA-100) has an interlayer loading of 100 μg/cm 2 and achieves power density equivalent to pristine Nafion at 0.6 V. Crucially, under accelerated stress testing, this membrane exhibits 1.8x higher chemical durability compared with a conventional membrane, maintaining superior voltage stability and superior power output retention at 0.6 V. These findings establish interlayer engineering as a scalable and effective strategy to overcome the durability–performance trade-off in PEM fuel cells. • Multilayer PEMs designed with a PVA/PVS gas barrier interlayer. • Effect of interlayer thickness on PEFC performance is systematically studied. • Optimized interlayers do not negatively impact initial cell performance. • Significantly improved durability compared to equivalent Nafion membranes. • More stable rated power output than Nafion during the durability test.