Alleviated ammonia crossover in thermally regenerative ammonia-based batteries by optimizing the introduced intermediate-chamber

Abstract

Thermally regenerative ammonia-based batteries (TRABs) are promising for harvesting low-grade waste heat and their performance is seriously limited by the general phenomenon of ammonia crossover. The feasibility of further promoting the performance of an intermediate-chamber TRAB was investigated in this work. It is highlighted that these investigations are centered around the physical properties and chemical reactions of NH3. To further enhance the alleviation of ammonia crossover, the ammonia absorption capacity of the buffer solution is very crucial. After introducing an intermediate chamber (TRAB-C) between the anode and cathode, ammonia crossover was alleviated in TRAB-C although the voltage output decreased due to the increased ohmic resistance. Concerning the intermediate chamber, the different operating conditions including flow condition, reactor placement, and electrolyte components would not only affect the ammonia crossover but also influence the electricity generation. To obtain the optimized condition, a performance evaluation criterion (PEC) was proposed to assess the electricity generation characteristic based on the maximum power density, energy density, and power generation. The results indicated that TRAB-C with flowing supporting electrolyte had the highest PEC value, suggesting the optimized design for TRABs.