Structure of ionic liquids under external electric field: a molecular dynamics simulation

Understanding the structure of ionic liquids under external electric field (EEF) is very important for their applications in many fields, such as cells, electrowetting and electrospray. An all-atom molecular dynamic simulation was performed under EEF for [C2MIM][BF4] in order to explore the structure and properties of ionic liquids. It is found that EEF can change the distribution from disorder to order and influence the shape of cations. We investigated the hydrogen bond further and found that the hydrogen bond network can be destroyed when EEF reaches a critical value (1.14 V/angstrom). Due to the order's arrangement of ions under EEF, it is found that the diffusion coefficient of solute in the direction of electric field is greatly enhanced. However, the ions are diffused slowly in the perpendicular direction to the electric field when EEF exceeds the critical value.