Acid–gel-immobilized, nanoporous composite, protonic membranes as low cost system for Direct Methanol Fuel Cells

An alternative, low cost, proton conducting electrolyte, designed for low and intermediate temperature DMCF and formed by new type of nanoporous, composite membrane in which sulphuric acid is immobilized by gelification, is here reported. The membrane is based on a polyvinylidene fluoride polymer matrix containing dispersed SiO2 ceramic powder at nanoparticles size. The stability of the immobilized sulphuric acid gel combined with the favorable swelling effect of the extended membrane porosity give to the membrane a high proton conductivity, a low methanol crossover and a satisfactory thermal stability. Good performances both at room and intermediate temperatures are showed by Direct Methanol Fuel Cells which use this system as separator.