Performance of a thermally regenerative ammonia-based flow battery with 3D porous electrodes: Effect of reactor and electrode design

The thermally regenerative ammonia-based batteries (TRABs) provide a promising approach for recovering electrical energy from low-grade waste heat. To promote the power generation, the reactor design, electrode pore density, and flow rate are investigated in this study. The results show that different reactor designs induce different mass transfer effects and significantly influence the power generation of the TRABs. TRAB without an electrolyte chamber but with a flow-through electrode on each side (TRAB-FT) results in the most effective mass transfer, obtaining the highest maximum power density (22.9 W m(-2)), total charge (1268.3C), and energy density (818.2 Wh m(-3)). Regarding the electrode pore density, the maximum performance increases initially and later decreases as the electrode pore density (pores per linear inch, PPI) of the electrode increases, and the optimal electrode pore density is 100 PPI for the TRAB-FT. This is attributed to the electrode porosity effect on the electrode specific surface and mass transfer resistance. In addition, the electrolyte flow rate significantly influences the performance of the TRAB-FT. With the increase in the flow rate, the power production shows an increasing trend with a gradually reduced increasing rate, obtaining an optimal electrolyte flow rate of 15 mL min(-1). (c) 2019 Elsevier Ltd. All rights reserved.