A Comparative Study of Dynamic Load Response of High Temperature PEM Fuel Cells

The high temperature polymer electrolyte membrane fuel cell (HT-PEMFC) based on the polybenzimidazole (PBI) membrane doped with phosphoric acid (H3PO4) presents a promising route in the development of fuel cell technology. The higher operating temperature of 160-200 degrees C results in an increased tolerance of the platinum catalyst to the carbon monoxide, an improved electrode kinetics, a higher-grade heat produced by the fuel cell, and a simplified water management due to the absence of liquid water in the system. In this study, the accelerated stress test protocol (AST) corresponding to the Driving Duty Cycle was used to characterize two sets of commercial MEAs, by Danish Power Systems Ltd. and FuMA-tech GmbH, respectively. Performance characteristics prior to and after the AST procedure were measured. The changes in the resistivity of the MEA were examined by electrochemical impedance spectroscopy (EIS). The EIS data were analysed and interpreted by a suitable equivalent circuit that consisted of a resistor and the Voigt's structure in series with constant phase elements. Conducted experiments and their analysis showed suitability of the HT-PEMFC technology in applications where dynamical load of the cell is expected. Moreover, the lower number of AST cycles did not seriously affect the cell performance. As expected, with increasing number of AST cycles, decrease in the cell performance was observed. In general, presented comparative study is expected to provide an extension of existing data for present and future development of diagnostic in the field of HT-PEMFC.