Graduate Student Jiajie Li

"Supercapacitive Swing Adsorption of Carbon Dioxide: Scaling using Bipolar Electrode Stacks and Implications for Direct Air Capture"

Supercapacitive Swing Adsorption (SSA) developed by our group is an electrostatic carbon capture technique, which is very simple and environmentally friendly compared with other electrochemical carbon capture techniques. SSA achieves reversible gas adsorption and desorption by capacitive charging and discharging the high surface area activated carbon materials. 1 In previous studies, we presented an SSA module constructed using a single pair of BPL 4x6 activated carbon electrodes and 1M aqueous NaCl as electrolyte in a radial gas flow system,2 which was able to separate CO2 from a 15%CO2/85%N2 flue gas simulant at a cell voltage of 1V. The performance was later improved by using garlic root-derived activated carbon at a cell voltage of 1.4 V.3 To make a significant impact on climate change, highly scalable CO2 capture techniques are needed to remove CO2 from the atmosphere at the gigaton scale. Recently, we demonstrated that SSA modules are readily scalable through the introduction of bipolar electrode (up to 11) stacks without reducing the adsorptive performance (~58 mmol·kg-1 sorption capacity), and with improvement of energetic performance (~60 kJ/mol, a substantially lower ~70% energy consumption compared to single cells).7 In addition, with the scaled up SSA system, there could be pairs of SSA modules which are connected in parallel, so that energy can be shuttled between the modules with minimal energy losses. Meanwhile, the high selectivity of the ionic liquid-solid mechanism suggests that SSA may be able to capture CO2 at very low concentrations and has significant potential for direct air capture (DAC). Based on the investigation of the relationships between SSA effect and different CO2 partial pressure (varying between 1% and 100%) in CO2/N2 gas mixtures, the adsorption declines less than proportional with CO2 partial pressure indicated that SSA sorption capacity may still be high enough for CO2 capture from air (~400 ppm). Currently, we are working on redesigning the scalable DAC-SSA modules with the wall flow structure by stacking stripes of bipolar electrodes having small gas flow channels to minimize pressure drop at high mass transfer for reducing the energy.

References
(1) Kokoszka, B.; Jarrah, N. K.; Liu, C.; Moore, D. T.; Landskron, K. Supercapacitive Swing Adsorption of Carbon Dioxide. Angew. Chemie - Int. Ed. 2014, 53, 3698–3701.
(2) Zhu, S.; Li, J.; Toth, A.; Landskron, K. Relationships between the Elemental Composition of Electrolytes and the Supercapacitive Swing Adsorption of CO2. ACS Appl. Energy Mater. 2019, 2, 7449-7456.
(3) Bilal, M.; Li, J.; Guo, H.; Landskron, K. High-voltage supercapacitive swing adsorption of carbon dioxide, Small, 2023, 2207834.
(4) Li, J.; Bilal, M.; Landskron, K. Scaling Supercapacitive Swing Adsorption of CO2 Using Bipolar Electrode Stacks, ChemRxiv. 2023 (preprint), https://doi.org/10.26434/chemrxiv-2023-62xjd