High-performance self-humidifying membrane electrode assembly prepared by simultaneously adding inorganic and organic hygroscopic materials to the anode catalyst layer

摘要

A novel self-humidifying membrane electrode assembly (MEA) has been successfully prepared by adding both a hydrophilic organic polymer (polyvinyl alcohol, PVA) and an inorganic oxide (silica) to the anode catalyst layer. This MEA shows excellent self-humidification performance under low-humidity conditions. A sample containing 3 wt.% PVA and 3 wt.% silica in the anode catalyst layer achieves a current density as high as 1100 mA cm~(-2) at 0.6 V, and the highest peak power density is 780 mW cm~(-2), operating at 60 ℃ and 15% relative humidity for both anode and cathode. The sample also shows excellent stability at low-humidity: after 30 h of continuous operation under the same conditions, the current density decreases just slightly, from 1100 mA cm~(-2) to ca. 900 mA cm~(-2), whereas with MEAs to which only PVA or silica alone had been added, the current densities after 30 h is just 700 mA cm~(-2) and 800 mA cm~(-2), respectively. The improved self-humidification performance can be attributed to the synergistic effect of two hygroscopic materials in the anode catalyst layer.