Enhancing electrochemical carbon dioxide capture with supercapacitors
Zhen Xu, Grace Mapstone, Zeke Coady, Mengnan Wang, Tristan Spreng, Xinyu Liu, Davide Molino, Alexander C. Forse
Abstract
Abstract Supercapacitors are emerging as energy-efficient and robust devices for electrochemical CO 2 capture. However, the impacts of electrode structure and charging protocols on CO 2 capture performance remain unclear. Therefore, this study develops structure-property-performance correlations for supercapacitor electrodes at different charging conditions. We find that electrodes with large surface areas and low oxygen functionalization generally perform best, while a combination of micro- and mesopores is important to achieve fast CO 2 capture rates. With these structural features and tunable charging protocols, YP80F activated carbon electrodes show the best CO 2 capture performance with a capture rate of 350 mmol CO2 kg –1 h –1 and a low electrical energy consumption of 18 kJ mol CO2 –1 at 300 mA g –1 under CO 2 , together with a long lifetime over 12000 cycles at 150 mA g –1 under CO 2 and excellent CO 2 selectivity over N 2 and O 2 . Operated in a “positive charging mode”, the system achieves excellent electrochemical reversibility with Coulombic efficiencies over 99.8% in the presence of approximately 15% O 2, alongside stable cycling performance over 1000 cycles. This study paves the way for improved supercapacitor electrodes and charging protocols for electrochemical CO 2 capture.