Proton Conductivity of Polymer Electrolyte Membranes during Transient Hydration and Dehydration Cycles

摘要

Most modeling work of the polymer electrolyte membrane fuel cell (PEMFC) assumes an equilibrium relationship between membrane water content and proton conductivity. However, evidence is provided which shows that deviations from the equilibrium relationship exist during the transient hydration and dehydration cycles. Although Nafion~R membranes follow a nearly symmetric water uptake and loss, dry membranes gain conductivity much faster than they absorb water while wet membranes lose conductivity at about the same rate they desorb water. This asymmetric behavior should be accounted for when predicting the transitional behavior of PEMFCs.