Performance of an All-Aqueous Thermally Regenerative Flow Battery Using CNT/Carbon Cloth Composite Electrodes

All-aqueous thermally regenerative battery (ATRB) is a promising electrochemical device for converting low-grade waste heat into electrical energy, while the low specific surface area of electrodes limits its performance. To improve the performance, the carbon nanotube/carbon cloth (CNT/CC) composite electrode with a highly specific surface area is proposed for ATRB in this study. The use of the CNT/CC composite electrodes induces a 37.4% higher maximum power density of ATRB (409.6 W/m2) compared with that of ATRB with the carbon cloth (CC) electrodes. The optimal CNT loading amount is determined to further enhance ATRB performance. Increasing the flow rate helps facilitate mass transfer, the optimal flow rate (50 mL/min) is selected considering the influence of the hydrodynamic loss. Concerning the expend application, a series stack of ATRB is constructed to successfully drive an electrochemical CO2 reduction device, resulting in a comparable Faraday efficiency for the conversion of CO2 to CO.