Investigation on sub-zero start-up of polymer electrolyte membrane fuel cell using un-assisted cold start strategy

Abstract

The technical barriers for commercialization of polymer electrolyte membrane fuel cell (PEMFC) are the startup ability and survivability at sub-zero temperatures. Ice formation causes cold start fail and volume change damages the cell components leading to performance decay. Many strategies are used to assist successful cold start and to reduce the performance decay. But, unassisted cold start is very crucial and needs attention. Here, an experimental protocol is reported for successful unassisted cold start using low temperature gas purging at various temperatures (-5,-8,-10,-15, and -20 °C) as well as to recover temporary performance decay. The stability of the membrane electrode assembly is also studied in freeze/thaw and sequential cold start cycles. At temperature −10 °C, there is small performance decay after the 6th freeze/thaw cycle. However, the subsequent cold start cycle shows significant performance decay after the 6th cycle. Changes in microstructures and loss of hydrophobicity in the gas diffusion layer are attributed to the performance decay in both freeze/thaw and sequential cold start cycles. The effect of cold start temperature on the performance of a PEMFC in subsequent freeze/thaw cycles is also studied. It shows that depending upon the start-up temperature, the preferential ice formation can affect the performance decay characteristics.