Relationships between the Elemental Composition of Electrolytes and the Supercapacitive Swing Adsorption of CO₂

The adsorptive and energetic performances for supercapacitive swing adsorption of CO 2 from 15% CO 2 /85% N 2 gas mixtures in the presence of different 1.0 M aqueous electrolytes with variable cations (LiCl, KCl, MgCl 2 ) and anions (NaF, NaBr, NaHCO 3, Na 2 SO 4 ) relative to 1.0 M NaCl as benchmark were determined. The adsorption and energetics for all investigated electrolytes are surprisingly similar; however, there is a somewhat greater dependence on the anions compared to the cations. The combination of the best-performing cation (Mg 2+ ) and anion (Br – ) in an MgBr 2 electrolyte led to best synergistic behavior and overall best performance. In addition, seawater was also found a suitable electrolyte performing similarly to the pure salt electrolytes. The results indicate that the liquid–solid mechanism of CO 2 adsorption occurs primarily at the positive electrode.