Power enhancement of passive micro-direct methanol fuel cells with self-sulfonation of P(VDF-TrFE) copolymer during lamination on Nafion membrane

Among the various advances that have taken place in fuel cells, efforts to reduce the methanol crossover and thereby increase fuel cell performance are important. One method by which crossover can be reduced is through introduction of hydrophobic surface on membrane which reduces the entry of methanol into the membrane. Here we show that coating of poly(vinylidenefluoride-trifluoroethylene) on Nafion results in reduction in crossover due to the introduction of hydrophobicity on the surface of the composite membrane which, in turn, improves the fuel cell performance. Further, FTIR results have shown that sulfonic-acid groups diffuse from Nafion into the poly(vinylidenefluoride-trifluoroethylene) during the dip-coating process which introduces proton conductivity in the lamination without the sulfonation process of polymer. Passive micro-direct methanol fuel cells are used as a platform for our experiments. Results show for the first time that 10 μm thick coating of poly(vinylidenefluoride-trifluoroethylene) on Nafion results in enhancement of power density.