In Situ Imaging of Liquid Water and Ice Formation in an Operating PEFC during Cold Start

Cold-start capability and survivability of polymer electrolyte fuel cells PEFCs in a subzero environment remain a major challenge for automotive applications. Its fundamental mechanisms are not fully determined, but it is recognized that product water becomes ice or frost upon startup when the PEFC internal temperature is below the freezing point of water. If the local pore volume of the cathode catalyst layer CL is insufficient to contain all of the accumulated water before the cell operating temperature rises above freezing, solid water may plug the catalyst layer and stop the electrochemical reaction by starving the reagent gases. In addition, ice formation may result in serious damage to the structure of a membrane electrode assembly MEA. In spite of the importance of PEFC cold-start capability and associated MEA durability, very few studies in the literature have focused on PEFC startup dynamics, freeze/thaw cycling,

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