Fuel cells – Phosphoric acid fuel cell | PAFC: Anodes and high-temperature membranes (also for HT-PEM fuel cells)

Abstract

Phosphoric acid fuel cell (PAFC) anodes accelerate the hydrogen oxidation reaction rate. The recommended PAFC anode catalyst is platinum-ruthenium alloy on a graphitized carbon support. For HT-PEM fuel cells, platinum catalysts are used. The anode materials must be stable at high operating temperatures in phosphoric acid and inexpensive to commercialization. During operation, hydrogen starvation may cause reverse polarization and electrochemical corrosion of the anode material. Carbon monoxide in the hydrogen-rich fuel gas may deteriorate cell performance especially at low operation temperatures. The operation at high temperatures requires maintaining the concentration of phosphoric acid at optimum level. At the same time, depleted reactant gases must be able to escape from the anode structure without impeding the supply of fresh reactants. The microstructure of the anode, such as catalyst layer and substrates, is important to increase the utilization of anode catalysts and to improve the anode performance, too.