Development of polybenzimidazole/graphene oxide composite membranes for high temperature PEM fuel cells

Abstract

In this study, phosphoric acid doped Polybenzimidazole/Graphene Oxide (PBI/GO) nanocomposite membranes were prepared by dispersion of various amounts of GO in PBI polymer matrix followed by phosphoric acid doping for high temperature proton exchange membrane fuel cell (HT-PEMFC) application. The structure of the PBI/GO composite membranes was investigated by X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and by thermogravimetric analysis (TGA). The introduction of GO into the PBI polymer matrix helps to improve the acid doping, proton conductivity and acid leaching properties. The SEM analyses have proved the uniform and homogeneous distribution of GO in composite membranes. The composite membranes were tested in a single HT-PEMFC with a 5 cm2 active area at 165 °C without humidification. HT- PEMFC tests show that PBI/GO composite membrane with 2 wt. % GO content performed better than bare PBI membrane at non humidified condition. At ambient pressure and 165 °C, the maximum power density of the PBI/GO-1 membrane can reach 0.38 W/cm2, and the current density at 0.6 V is up to 0.252 A/cm2, with H2/air. The results indicate the PBI/GO composite membranes could be utilized as the proton exchange membranes for HT-PEMFC.