Summarising, the relationship between the current density and the CO2 adsorption capacity is ruled by the trade-off between two competing effects. One is the thermodynamic control when charging slowly and the second is mass transport which limits adsorption capacity when charging fast. This suggests that any SSA set up would have a peak in the adsorption capacity, though the current density that this occurs at would vary between systems. For example, using a flow set-up and mixed gases of 15% CO2 and 85% N2, Landskron et al. showed that under the same charging conditions, the current density of 20 mA g -1 gave the best performance. Understanding and exploiting kinetic and thermodynamic effects in SSA is an important direction of future research.