title: Mitigation of chemical membrane degradation in fuel cells: understanding the effect of cell voltage and iron ion redox cycle.
abstract: Chemical membrane degradation through the Fenton's reaction is one of the main lifetime-limiting factors for polymer-electrolyte fuel cells. In this work, a comprehensive, transient membrane degradation model is developed to capture and elucidate the complex in situ degradation mechanism. A redox cycle of iron ions is discovered within the membrane electrolyte assembly, which sustains the Fe(II) concentration and results in the most severe chemical degradation at open circuit voltage. The cycle strength is critically reduced at lower cell voltages, which leads to an exponential decrease in Fe(II) concentration and associated membrane degradation rate. When the cell voltage is held below 0.7 V, a tenfold reduction in cumulative fluoride release is achieved, which suggests that intermediate cell voltage operation would efficiently mitigate chemical membrane degradation and extend the fuel cell lifetime.
authors.affiliation: School of Mechatronic Systems Engineering, Simon Fraser University, 250-13450 102 Avenue, Surrey, BC V3T0A3 (Canada), Fax: (+1) 778-782-7514.
authors.forename: Ka Hung
authors.initials: KH
authors.lastname: Wong
authors.forename: Erik
authors.initials: E
authors.lastname: Kjeang
mesh_terms: D004553:Electric Conductivity; D011211:Electric Power Supplies; D004579:Electron Transport; D006861:Hydrogen Peroxide / Q000737:chemistry; D007501:Iron / Q000737:chemistry*; D008567:Membranes, Artificial; D008956:Models, Chemical
chemical_list: C045076:Fenton's reagent; D008567:Membranes, Artificial; D006861:Hydrogen Peroxide; D007501:Iron
keywords: durability; fuel cells; iron; membranes; modeling