Material evaluation and development trend of polymer electrolyte fuel cells

Abstract

Polymer electrolyte fuel cells (PEFCs) have been developed as power sources of electric vehicle and home co-generation system. In order to develop PEFC system, the development and the research of materials i.e. electrode catalyst, electrolyte membrane, and catalyst of fuel processing have been important. The electrode catalysts are required higher activity for oxygen reduction reaction and hydrogen oxidation reaction under CO containing fuel. The electrolyte membranes are required to maintain their ionic conductivity under dry atmosphere. CO selective oxidation catalyst, which is one of fuel processing catalysts, are required their selectivity and activity of CO oxidation. The new material must be evaluated as their own characteristics and the fuel cell assembly. For the estimation of the fuel cell assembly, the cell voltage as a function of the current must be measured. The cell voltage is important factor, because it indicates the efficiency of the energy conversion. The cell performance is affected the composition of fuel and oxidant gas, flow rate of fuel and oxidant gas, operating pressure, and cell temperature. Especially, humidity of gases, which is one of gas composition parameter, greatly affect to the cell performance because of the property of the electrolyte membrane. In the cell performance measurement, these parameters must be controlled accurately.