Natural and synthetic solid polymer hybrid dual network membranes as electrolytes for direct methanol fuel cells

Hybrid dual-network membranes comprising chitosan (CS)–polyvinyl alcohol (PVA) networks crosslinked with sulfosuccinic acid (SSA) and glutaraldehyde (GA) and modified with stabilized silicotungstic acid (SWA) are reported for their application in direct methanol fuel cells (DMFCs). Physico-chemical properties of these membranes are evaluated using thermo-gravimetric analysis and scanning electron microscopy in conjunction with their mechanical properties. Based on water sorption and proton conductivity measurements for the membranes, the optimum content of 10 wt.% SWA in the membrane is established. The methanol crossover for these membranes are studied by measuring the mass balance of methanol using density meter and are found to be lower compared to Nafion-117 membrane. The membrane–electrode assembly with 10 wt.% stabilized SWA–CS–PVA hybrid membrane with SSA and GA as crosslinking agent delivers a peak power density of 156 mW cm⁻² at a load current density of 400 mA cm⁻² and 88 mW cm⁻² at a load current density of 300 mA cm⁻², respectively, in DMFC at 70 °C.