Polymer electrolyte fuel cells based on phosphoric acid doped polybenzimidazole (PBI) membranes

In order to make fuel cells with high power density the structure and morphology for the three-dimensional gas diffusion electrodes (GDEs) are very important. A preparation technique for GDEs for phosphoric acid doped polybenzimidazole (PBI) is presented. Teflon treatment of the backing material was found to be beneficial for the performance of the electrodes, and explained by higher total porosity. In general the open circuit voltage (OCV) with PBI-based cells is 0.9 V. The observed low OCV was explained by slow kinetic for the oxygen reduction and cross over of the reactants. The performance of the fuel cells is found to increase with increasing temperature; this was explained by faster reaction kinetic and higher membrane conductivity. A typical power output was 0.3–0.4 W cm−2 at 0.6 V and 175 °C.