New crowding states of ionic liquid induced by configuration change of ion adsorption on charged electrode

In ionic liquid based electrical double layer, crowding state is used to explain the unique shape of the differential capacitance curve. However, the differential capacitance values are still significantly underestimated and an impractically high electrode potential is required to observe the crowding state in simulations. In this study, based on the electrode charge distribution obtained from joint density functional theory calculations, we successfully predict the differential capacitance curve with both shape and magnitude correct. At the same time, we find a new type of ionic liquid crowding state at low potentials within the electrochemical window, which is induced by adsorption state transition of organic ions. These results provide new insights in understanding ionic liquid at electrified interfaces. [Display omitted]