Impacts of supercapacitor electrode structure on electrochemical CO2 capture

Abstract

Anthropogenic CO2 emissions cause global warming, driving the need for decarbonisation technologies. Supercapacitors, originally designed for energy storage, are emerging as energy-efficient and robust devices for electrochemical CO2 capture. However, impacts of electrode structure and charging protocols on CO2 capture performance remain unclear. This study develops structure-performance relationships for supercapacitor electrodes at different charging conditions. In general, we find that electrodes with large surface areas and low oxygen functionalisation perform the best, while a combination of micro- and meso-pores is essential to achieve fast capture rates. By combining these structural features, the YP80F activated carbon electrode shows the best CO2 capture performance (350 mmolCO2 kg–1 h–1 and 18 kJ molCO2–1, under 300 A kg–1, 0.8 V and pure CO2), a long lifetime over 12000 cycles, and promising CO2 selectivity over O2 and N2. This study paves the way to develop supercapacitor electrodes for electrochemical CO2 capture.

Oxygen-assisted supercapacitive swing adsorption of carbon dioxide

“…No data was provided for the adsorptive and energetic performance of the CO2/N2/O2 mixtures with the negative electrode as gas-exposed electrode. 22 Here, we report that oxygen assists the supercapacitive swing adsorption of carbon dioxide when the negative electrode as the gas-exposed electrode, leading to adsorption capacities that are up to 11 times enhanced. All experiments were performed in batch-mode under continuous gas flow allowing for actual gas separation.…”

“…[19][20][21] Recent studies from us and other researchers highlighted the possibility of enhancing the CO2 sorption capacity by tuning the voltage window, investigated critical factors contributing towards performance improvements, and proposed biomass-and non-biomass derived carbon-based materials with high surface areas and capacitances for enhancing SSA performance. 17,[22][23][24] To date, a maximum sorption capacity of ∼520 mmol.kg -1 at an energy consumption of ∼130 kJ.mol -1 CO2 is reported with 15% CO2/85% N2 gas mixtures. 24 Recently, Forse et el.…”

“…reported the supercapacitive swing adsorption of pure O2, and 20% CO2/15% O2/ 65% N2 gas mixtures. 22 Partially reversible O2 adsorption was measured in experiments with pure O2 when the negative electrode was the gas-exposed electrode, but the amounts were not quantified. No significant O2 adsorption was measured with the positive electrode as gas-exposed electrode.…”