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

• Optimization of DMFC performance with N117 at 50 °C for portable applications.
• Optimal balance between power density and methanol yield obtained with 1 M methanol.
• Methanol yield of 80% at low methanol concentrations and high current densities.
• Best performances with 2 mg cm−2 50 wt% PtRu and cathode with microporous layer.

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 5 cm2 cell performance were investigated. At 50 °C, a maximum power density of 84 mW cm−2 was calculated (50 mW cm−2 @ 400 mV) for the best performing MEA with a Nafion 117 membrane, 2 mgPt cm−2 at both anode and cathode with 2 M 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 0.5 M methanol solution and amounted to about 75% at 40 mW cm−2 @ 400 mV.

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