If the supercapacitor is charged faster with current densities greater than 30 mA g -1 then there is a decrease in the adsorption capacity (Figure ). For this faster charging regime, the peak or trough of the pressure curves shift towards the right-hand side showing a delayed response of the pressure curve compared to the change in the cell voltage (as indicated by the red arrows in Figure ). This indicates that the whole system, including both electrodes, is becoming mass transport limited where the change in the voltage is too fast for the slow-moving diffusion of CO2 and bicarbonate ions. This limits the adsorption capacity causing its decrease at faster current densities.