Abstract
This study reports the cell performance of direct methanol alkaline fuel cells (DMAFCs) employing hydroxide conducting membranes. The membrane electrode assemblies (MEA) consisted of carbon-supported platinum/ruthenium for anode, platinum for cathode, and poly(vinyl alcohol) (PVA)/carbon nano-tube (CNT)/KOH membranes as polymer electrolytes. The CNT was grafted with PVA chains and PVA/CNT composite membranes were prepared using a direct mixing process and solution casting method. The aggregated hydrophilic regimes of CNT served as hydroxide-conducting micro-channels and increased the ionic conductivity of the KOH-doped PVA/CNT films. The electrolyte with CNT exhibited higher maximum power density and could be operated at a higher current density due to the reduction in methanol crossover. The maximum power density and open-circuit voltage was monitored for DMAFCs at various operating conditions. The effects of methanol concentration, methanol/KOH ratio and operating temperature on the cell performance were determined and discussed with the electrolyte characteristics.