Anode-Design Strategies for Improved Performance of Polymer-Electrolyte Fuel Cells with Ultra-Thin Electrodes

Summary We report results of systematic, holistic, diagnostic, and cell studies to elucidate the mechanistic role of the experimentally determined influence of the anode gas-diffusion layer (GDL) on the performance of ultra-thin electrode polymer-electrolyte fuel cells, which can further enable fuel-cell market penetration. Measurements of product water balance and in situ neutron imaging of operational membrane-electrode-assembly water profiles demonstrate how improved performance is due to a novel anode GDL fiber-density modulated structure at the micrometer scale that removes water preferentially out of the anode, a key strategy to manage water in these cells. The banded structure results in low transport-resistance pathways, which affect water-droplet removal from the GDL surface. This interfacial effect is unexpectedly shown to be critical for decreasing overall water holdup throughout the cell. These studies demonstrate a new material paradigm for understanding and controlling fuel-cell water management and related high-power technologies or electrodes where multiphase flow occurs.