Ionic liquid-electrode interface: classification of ions, saturation of layers, and structure-determined potentials

Progress in electrochemical applications of ionic liquids builds on an understanding of electrical double-layer. This computational study focuses on structure-determined quantities – maximum packing density, potentials and capacitances – evaluated using a one-electrode electrical double-layer model. Interfaces of 40 studied ions are grouped into four distinct classes according to their characteristic packing at the model surface. The simulations suggest that the exact screening by a monolayer of counter-ions (preceding the crowding of ions) is unlikely for common ions within the electrochemical stability window of corresponding ionic liquids. This work discusses how the assessed structure-determined quantities can guide the experimental tuning of (electro/mechano)chemical properties and characterising the structure of ionic liquid-electrode interfaces.