Interfacial Structural and Dynamical Properties of [BMI+] [PF6 -] Ionic Liquids on the MXene Electrode: A Molecular Dynamics Simulation Study

Abstract

Abstract Two-dimensional MXene nanomaterials are attracting more and more research interests as electrodes in energy storage applications. In this work, the interfacial structural and dynamical properties of solvent-free ionic liquids ([BMI+] [PF6 -]) on the MXene electrode are investigated using molecular dynamics simulation. Multiple alternating structures of [BMI+] cation and [PF6 -] anions on the MXene surface are observed. Interestingly, the ion diffusion coefficients are remarkably reduced (by 30~40%) in the interfacial Helmholtz layer. Importantly, an asymmetric bell-shaped differential capacitance profile with a maximum capacitance of ~7.04 μF/cm2 is observed. This is chiefly correlated with the structural properties of counterions rather than coins in the interfacial areas.