Substrate-Free Gas Diffusion Layer Based on a Nonsolvent-Induced Phase Inversion Approach for High-Performance Proton Exchange Membrane Fuel Cells

The superior mass transfer capacity of the gas diffusion layers (GDLs) is the key to the design and fabrication of a high-performance proton exchange membrane fuel cell (PEMFC) for various applications. However, the conventional GDLs easily generate abrupt pore gradient change and interfacial resistance between the microporous layer and the carbon paper substrate, leading to mass transport limitation and ultimately leading to lower output power for the PEMFC. Here the substrate-free GDLs (sfGDLs) with varying thicknesses, bimodal pore distribution, and superhydrophobic surfaces were designed by nonsolvent-induced phase inversion and rapid solidification. The cell power density of sfGDL with thickness of 230 μm and mesopores of 85.41% exhibited maximal limiting current density of up to 6.31 A cm^-2 and peak power density of 1.60 W cm^-2 at high humidity, superior to that of sfGDLs reported in the literature under counterpart test conditions. In this work, the distinguishing performances verified that the synergistic effect of the appropriate thickness and abundant mesopores can significantly promote the mass transfer efficiency of membrane electrode assembly, ensuring gas transport to the catalyst layer and excellent cell performance.