Ammonia crossover in thermally regenerative ammonia-based batteries for low-grade waste heat recovery

Abstract

Ammonia crossover usually occurs in thermally regenerative ammonia-based batteries (TRABs) and significantly deteriorates the performance. In this study, the effect of ammonia crossover on the performance of TRABs and its influencing factors are studied. In addition, an ammonia-breathing thermally regenerative ammonia-based battery with an ammonia gas chamber (ATRB) is constructed by regulating the structure of the gas diffusion layer to control ammonia transfer in the anode. The results show that the cathode performance remarkably decreases with the increase of ammonia content in the cathode, and the amount of ammonia crossover increase with the rise of initial ammonia concentration, discharging current, and temperature. The visualization results show that TRAB with the ammonia diffusion layer can effectively alleviate the ammonia crossover by regulating ammonia transfer. The content of polytetrafluoroethylene (PTFE) in the gas diffusion layer significantly influences ammonia transfer to the porous anode and the cathode. The battery performance increases firstly and decreases later with the PTFE content, and an optimal PTFE content is 20%.