Performance of an Intermediate-Temperature Fuel Cell with a CsH5(PO4)2-Doped Polybenzimidazole Membrane

Abstract

CsH5(PO4)2-doped polybenzimidazole (PBI) membranes exhibit good proton conductivity and mechanical properties. However, their application in fuel cells is impeded by poor performance. In this study, a novel method is confirmed to greatly improve the performance of a fuel cell based on a CsH5(PO4)2-doped PBI membrane. By coating phosphoric acid (PA) on the surface of the catalytic layer of the gas diffusion electrode, the interfacial contact between the electrolyte membrane and catalytic layer is improved, thereby reducing the ohmic resistance and improving the fuel cell performance. The cell performance is improved by ∼700%. Moreover, the effects of humidity and temperature on the performance and resistance analysis of membrane electrode assembly with a CsH5(PO4)2—doped PBI membrane are studied. Testing under a temperature range of 160 °C–220 °C and humidity range from dry to 30% relative humidity, a maximum peak power density of 554 mW cm−2 is found at 200 °C and 20% relative humidity. A durability test of the membrane electrode assembly indicates that its performance remains stable in a humid atmosphere but gradually decreases in a dry atmosphere. This means for the long-term operation of the molten proton conductor electrolyte membrane, a humid atmosphere is necessary to inhibit the performance decay.