Study of substrate-free microporous layer of proton exchange membrane fuel cells

The gas diffusion layer (GDL) is a vital constituent of proton exchange membrane fuel cells (PEMFCs), which directly affects the performance and cost of PEMFCs. Also, the GDL integration can simplify the structure of PEMFC. Herein, a novel substrate-free microporous layer (sfMPL) has been successfully prepared by a dry-press method, which broadens the usable humidity range of PEMFCs and improves the performance under different humidity conditions. Precisely, the maximum power density of a single-cell assembled by sfMPL (with optimised 10 wt.% binder content and 1.0 g pore-forming agent) is 754 mW cm(-2) at 40% relative humidity, which is 36.6% higher than that with conventional GDL (552 mW cm(-2)). Furthermore, the sfMPL shows outstanding stability after high potential oxidation (1.6 V vs RHE). Our results highlight a promising new class of low-cost, substrate-free MPL for PEMFCs and provide a basis for future research on substrate-free MPL.