Polybenzimidazole Membranes as Nafion Replacement in Aqueous HCl Electrolyzers

Abstract

We demonstrate the use of para-polybenzimidazole (PBI) membranes as replacements for Nafion membranes in aqueous HCl oxygen-depolarized electrolyzers. Both para-PBI and densified para-PBI membranes reduce the cell voltage needed at 0.5 A cm–2 by ≥100 mV. We examine the effect of HCl(aq) flow rate, back-pressure, electrolyzer temperature, and, for the densified para-PBI membranes, H3PO4 swell time on electrolyzer performance. Increased proton conductivity, measured as reduced area-specific membrane resistance, is identified as the primary mechanism to explain the improved performance of the electrolyzer.