Preparation and characterization of novel pyridine-containing polybenzimidazole membrane for high temperature proton exchange membrane fuel cells

A novel pyridine-containing polybenzimidazole (PDA-PBI) membrane was developed as a candidate for high-temperature polymer electrolyte membrane fuel cells. Aiming to improve the solubility and proton conductivity of the ionomer, a diacid monomer, 4,4′-(pyridine-2,6-diylbis(oxy))dibenzoic acid (PDA), was synthesized and condensation polymerized with 3,3′-diaminobenzidine (DAB) to prepare a polymer containing ether groups and pyridine rings. The soluble PDA-PBI membranes were prepared by solution casting method and then soaked in phosphoric acid solution. The polymers were characterized by Fourier transform infrared spectroscopy, element analysis and thermogravimetric analyses. The PDA-PBI has good thermal stability with onset decomposition temperature up to 350 °C. The proton conductivity of the prepared membrane is 11 mS cm−1 at 25 °C and 83 mS cm−1 at 160 °C without any humidification. The evaluations of fuel cell performance were conducted using the PDA-PBI membranes and a peak power density of 460 mWcm−2 was obtained at 160 °C with unhumidified hydrogen and oxygen.