Performance of a thermally regenerative ammonia-based battery using gradient-porous copper foam electrodes

Gradient-porous copper foam electrodes were applied to alleviate the adverse effects of the uneven current distribution of electrodes along the electrolyte flow direction in thermally regenerative ammonia-based batteries(TRABs).The results indicated that gradient-porous copper foam with a decreasing pore size(TRAB-LMS)provided the most uniform current distribution and generated the highest power density(15.5 W/m^(2)),total charge(1800 C)and energy density(1224 W h/m^(3)).With the increase in flow rate,the power density of the TRAB-LMS increased considerably within a certain range and then decreased slightly,with the optimal flowrate at 15 mL/min.Under the optimal flow rate,the performance of TRAB-LMS increased when the ammonia concentration rose from 0.5 to 2 M(1 M=1 mol L^(-1));however,it decreased slightly when the ammonia concentration further increased to 3 M.The slight decrease in the cathode potential suggested that the flow and ammonia concentration beyond the optional values facilitated not only the transfer of ammonia into the porous anode,but also the crossover of ammonia from the anode to the cathode.

Graphene oxide modified membrane for alleviated ammonia crossover and improved electricity generation in thermally regenerative batteries

Thermally regenerative batteries(TRBs) are promising for harvesting low-grade waste heat into electrical power. However, the ammonia crossover from anode to cathode causes self-discharge and then leads to the decay of capacity. To alleviate the ammonia crossover and improve electricity generation, a stable graphene oxide(GO) modified anion exchange membrane(AEM) was proposed. Compared with the original AEM, the GO modified AEM with a 39.5% lower ammonia permeability induces a 24.3% higher maximal power output and 20.2% higher energy density in TRBs. Together with the visualization result,it was demonstrated the ammonia crossover was effectively alleviated by GO modifying the AEM not at a cost of the reduced battery performance, indicating the promising application in future TRBs.