Spray-casting ABPBI membranes for high temperature PEM fuel cells

Abstract

The preparation and characterization of membranes of poly[2,5-benzimidazole] (ABPBI) by spray casting at room temperature from an ethanol solution is described. The prepared membranes doped with 11 M H3PO4 sorbed 1.5 molecules of acid per imidazole ring exhibiting a proton conductivity of 0.05 S · cm−1 at 153◦C. The 80 μm thick, homogeneous, membranes obtained were used for the preparation of a membrane electrode assembly (MEA). Fuel cell test conducted with the prepared MEA at temperatures between 100 and 180◦C shows an increase in the performance with temperature, with a maximum power density of 200 mW · cm−2 at 180◦C. The described ABPBI membrane preparation method from an ethanol solution at low temperature opens a simple route for overcoming the processability problems of the aforementioned polymer.