Atomistic simulation of conduction and diffusion processes in Nafion polymer electrolyte and experimental validation

Conduction and diffusion processes in Nafion 117 polymer electrolyte were analyzed using all-atom molecular dynamics models. The diffusivity of methanol, water, hydronium, and proton in Nafion and the conductivity of Nafion were evaluated in a wide range of temperatures from 20 to 120 degrees C for various water contents (lambda = 3.0, 13.0, and 22.0). To validate the simulation results, the conductivity of Nafion was evaluated using a four-probe conductivity measurement apparatus at temperatures from 20 to 120 degrees C in humidified air (RH = 50 to 100%) and in liquid water. The permeability of methanol in Nafion was evaluated using a high-temperature membrane diffusion cell. The calculated values and experimental results are generally in good agreement with maximum differences within 50% at room temperature or 100% at higher temperatures. (c) 2006 The Electrochemical Society.