Precisely Engineered Microporous Layers for Proton Exchange Membrane Fuel Cells with High Power Density

Mass transport is vital in electrochemical processes as it directly relates to the energy conversion efficiency and limits the chemical reaction rate, which also defines the output voltage and power density of proton exchange membrane (PEM) fuel cells. Herein, combined with water and gas two-phase transport, the optimal structure, especially the pore size of the microporous layer (MPL), is analyzed as the only variable by simulations. Based on the simulation results, the precisely tailored MPLs with 32 ± 5 nm hydrophobic pore sizes are achieved experimentally using kinetic control of the pore-forming agents. Notably, up to 1.572 W cm–2 is reached in a single cell assembled from the above MPL, a significant increase compared with traditional carbon black-based MPLs. This high power density comes from a balance between water and gas transport. The results will broaden our understanding of the water and gas flow in fuel cells and give guidance for the engineering design of the next-generation sustainable electrochemical apparatus with high output and low costs.