Optimized Interfaces for PBI-Based High-Temperature Direct Ethanol Fuel Cells

The present study combines innovative strategies aiming at enhanced performance of direct ethanol fuel cells (DEFC) by modifying interfaces at both electrodes and electrolyte. Increasing the operating temperature to 180 °C to promote faster kinetics and thermally activated processes taking place in DEFC was possible by using phosphoric-acid-doped PBI (polybenzimidazole) composite electrolytes. The properties of the PBI electrolytes were improved by adding SiO2 as an inorganic second phase, promoting an increase in the proton conductivity and inhibiting ethanol crossover. Optimizing electrode reactions by increasing the triple-phase boundary was demonstrated by using a powdered-based PBI “ionomeric” concept to boost the performance of the proton exchange membrane fuel cell. The electrochemical characterization of the high-temperature direct ethanol fuel cells (HT-DEFC) showed that combining the strategies for the optimized electrode and electrolyte was crucial for increasing the performance of membrane electrode assemblies operating at 180 °C.