Appropriate balance between methanol yield and power density in portable direct methanol fuel cell

Abstract

This work aimed at the development of efficient catalysts and gas diffusion electrodes for a portable DMFC. The influence of catalyst loading, methanol concentration, working temperature, cell orientation, microporous layer and membrane thickness on 5cm2 cell performance were investigated. At 50°C, a maximum power density of 84mWcm−2 was calculated (50mWcm−2 @ 400mV) for the best performing MEA with a Nafion 117 membrane, 2mgPtcm−2 at both anode and cathode with 2M CH3OH solution and air at ambient pressure. This good performance is attributed to both the highly dense and reactive catalysts as well as the presence of a microporous layer at the cathode that allows an optimal mass transport of reactants and products within the gas diffusion electrode. Methanol yield was found to be principally dependent on methanol concentration feed at the anode. Best performances in terms of methanol yield were obtained with the 0.5M methanol solution and amounted to about 75% at 40mWcm−2 @ 400mV.