In this work we have found new insights into the mechanism of SSA with both experiments and computational modelling. The COMSOL model showed that when the supercapacitor is charged in a negative direction, the concentration of bicarbonate ions decreases at the top electrode allowing for more CO2 to diffuse in leading to the capture of CO2. The converse is true when charging in a positive direction where an increase in the bicarbonate concentration at the gasexposed electrode leads to the desorption of CO2. The limiting behaviours of the system were probed to understand the difference in the kinetic and thermodynamic regimes. When the supercapacitor was charged slowly or had a long voltage hold, the capture of CO2 was reversible showing that SSA is inherently a kinetic effect and only occurs on shorter timescales. SSA is also limited by the current density where, when charging fast enough, the system becomes mass transport limited. By rational design of the device and materials to allow for faster mass transport of CO2 and HCO3 -ions, faster current densities would be favoured thus improving the productivity of the CO2 capture. This information can be used to inform future device and material design to increase the performance of SSA.