Fast Ion Transportation Associated with Recovering Hydration Shells in a Nanoelectrolyte between Conical Carbon Nanopores during Charging Cycles

Electric double-layer capacitors using nanoporous carbons store electricity efficiently, with high power density and a long life. Smooth ion adsorption and a high concentration of carbon nanopores are crucial factors for achieving high-capacitance performance in such devices. Previous studies have investigated the static properties of nanoelectrolytes using experiments and simulations. An analysis of the dynamic properties performed here sheds new light on the mechanism of ion transportation between electrodes. In this study, the dynamics of a nanoelectrolyte under switching between plus and minus partial charges in conical carbon electrodes were investigated using molecular dynamics simulations. Fast ion transportation between the conical carbon electrodes was observed during charging and discharging cycles, behavior that was associated with increasing hydration numbers and decreasing hydrogen bonding numbers. Smooth ion transportation was thus made possible by the breaking of hydrogen bonding networks that resulted from the recovery of the hydration shell.