Design and experimental validation of an HT-PEFC stack with metallic BPP

This paper provides detailed insight into the design, construction, production and verification of a metallic bipolar plate for High Temperature Polymer Electrolyte Fuel Cell stacks. With a focusing on applications with power demands of 5-10 kW, the active cell area is set to a maximum of 100 cm2. The double-plate-concept allows for liquid cooling in the inner bipolar plate compartment. Due to the bipolar plate production by hydroforming of thin stainless steel foils the structure of the coolant compartment is dependent on the gas flow field design. To ensure proper cooling functionality a co-design is necessary. The flow field design, in conjunction with the flow configuration of the reactants (reformate, air) and coolant, considers the effects of hydrogen and oxygen depletion on current density distribution, as well as the temperature profile on carbon monoxide poisoning. These specifications are based on previously published results. For validation, a 5-cell stack with commercial Membrane Electrode Assemblies was operated at 160 °C and 0.2 A/cm2 and regularly interrupted for the polarization curve measurement. After 4700 h of continuous operation, the test was terminated due to a rapid voltage drop in one of the cells. In this paper, it is shown that novel metallic bipolar plates from thin metal sheets can be used for the long-term operation of High Temperature Polymer Electrolyte Fuel Cell stacks.