Operation Strategies Based on Carbon Corrosion and Lifetime Investigations for High Temperature Polymer Electrolyte Membrane Fuel Cell Stacks

This paper is aimed to develop operation strategies or high temperature polymer electrolyte fuel cells (HT-PEMFCs) stacks in order to enhance the endurance by mitigating carbon oxidation reaction. The testing protocols are carefully designed to suit the operating cycle for the realistic application. A 5 cell co-flow stack is assembled with BASF Celtec((R)) P membrane electrode assembly (MEA) with an active area of 163.5 cm(2). The oxidation rate of carbon is systematically investigated employing potentiostatic experiments under variation of both cell voltage and temperature using on-line mass spectrometry. The experimental results show that more CO2 is measured for the open circuit voltage (OCV) operation, indicating that the lifetime of the stack is strongly affected by a factor of approximately 12-26 between OCV and 700 mV depending on temperature. Protective start-stop algorithms are developed to avoid the formation of aggressive cell potentials. The startup procedures let degrade the catalyst support to a higher extent than the stop procedures, which is presumably due to both OCV exposure and hydrogen front passing through the anode. A model for lifetime prediction is developed from carbon corrosion experiments and validated with a durability test for 1,562 cycle events.