The role of an anode microporous layer in direct ethanol fuel cells at different ethanol concentrations

Ethanol crossover and ethanol electrooxidation kinetic effects on direct ethanol fuel cell (DEFC) performance were determined at different ethanol feed concentrations for cells fabricated with and without an anode microporous layer (MPL). Several characterization techniques were used, including cell performance curves, anode polarization, electrochemical impedance spectroscopy (EIS) and ethanol crossover by the voltammetric method. It was found that the optimum ethanol feed concentration depended on the anode structure design and the cell current density operation. A microporous layer could reduce ethanol crossover but induced high mass transfer resistance, resulting in a slow ethanol electrooxidation reaction rate. However, ethanol crossover was not the dominant factor affecting DEFC performance for the ethanol feed concentration range (0.5-5.0 M) studied. The MEA without an anode MPL exhibited better performance than the one with an MPL for the entire range of ethanol concentration.