A high performance ion-solvating membrane-type direct ammonia fuel cell

Abstract

Low-temperature direct ammonia fuel cells (DAFCs) are considered as an ideal power source for transportation due to their high energy density, easy storage and transportation, and reasonable cost. However, the alkaline electrolyte membranes suitable for DAFCs needs further research and development to achieve high power density output. Here, we conducted a pioneering study on the application of polybenzimidazole (PBI) based ion-solvating membrane (ISM) in DAFCs. The potential effect of ammonia crossover on the membrane properties during the operation of PBI ISMs based DAFCs was revealed through the treatment of poly(2,2'-(1,4-naphthylene)-5,5′-bibenzimidazole) (NPBI) and poly(2,2'-(meta-phenylene)-5,5′-bibenzimidazole) (m-PBI) ISMs with ammonia-alkali solution. More importantly, the performance of DAFCs based on PBI ISMs was reported for the first time, and the NPBI ISM based DAFC exhibited an exceptional peak power density (PPD) of 80 mW/cm2 at 80 °C, outperforming other alkaline ion membranes under identical testing conditions. Further optimization of operating conditions indicated that the performance of NPBI ISM-based DAFCs was highly dependent on concentration of KOH. This work provides a new direction and guidance for the development of alkaline polyelectrolyte membranes suitable for high performance low-temperature DAFCs.