Here we explore the impact of three different charging protocols on the adsorption capacity of SSA, similar to previous work. These are referred to as: (1) "negative charging" where the gasexposed electrode (Figure ) was negative for the duration of the cycle (Figure ), ( ) "positive charging" where the gas-exposed electrode was positive for the duration of the cycle (Figure ), and (3) "switching" where the negative and positive charging protocols were combined to take advantage of the full potential window (Figure ). Three-electrode electrochemistry measurements of the supercapacitors under air, nitrogen and carbon dioxide is shown in SI Figure . For the purpose of this investigation, a static gas reservoir of pure CO2 was used for our experiments to simplify the system and allow for the elucidation of the mechanism. The charging mode significantly affects the carbon dioxide capture behaviour of the system (Figure , 1c, 1d and SI Figure for the full dataset). In the negative charging mode, carbon dioxide capture takes place when the gas-exposed electrode is subjected to negative potentials (as seen by a decrease in the pressure), while carbon dioxide release occurs during discharge (Figure ). In contrast when in the positive charging mode (Figure ), carbon dioxide release occurs when the gas-exposed electrode is subjected to positive potentials, and carbon dioxide capture occurs during discharge. These measurements show that the asymmetry in the design of the gas cell, where a single electrode is preferentially exposed to the gas reservoir, manifest in an asymmetry in the behaviour of the device. Since the supercapacitor studied here is a symmetric device (with the exception of one electrode being preferentially exposed to gas), the data implies that SSA is a non-equilibrium effect. Indeed, at thermodynamic equilibrium, the same CO2 capture (or release) behaviour would be expected for both the negative and positive charging modes, which