A hybrid membrane of modified polybenzimidazole and heteropoly acid for direct methanol fuel cell

We have synthesized monomer for modified polybenzimidazole (mPBI) and use the monomers to synthesize the polymer. The properties of the monomer and polymer are characterized by FTIR. The analysis results show that the molecular structure of the synthesized monomer and mPBI is consistent with our designed structure. An effective proton exchange membrane is then developed in this work by doping silicotungstic acid hydrate (SWA) -SiO₂ in mPBI to combine the desired lower methanol permeability from mPBI with high proton conductivity of SWA. The proton conductivity of the proton exchange membrane is characterized by AC impedance spectroscopy under realistic operating conditions. We found when the new membrane contains 37.5wt% of SWA -SiO₂/PBI, the membrane is very stable mechanically at the operation conditions and its proton conductivity is excellent, 3.12×10^-3 Scm^-1 at room temperature.