Atomic-scale insights into phosphorene-ionic liquid interface with Ab initio molecular dynamics

Abstract

The development of high-performance electrodes for supercapacitors and batteries remains hindered by an incomplete atomic-scale understanding of how material structure and polarization govern electric double-layer formation. In this work, we employ ab initio molecular dynamics (AIMD) simulations to probe the interface between a neutral phosphorene electrode and the ionic liquid EMIM-BF4, elucidating the mechanisms of charge redistribution and ionic ordering. Key findings include a detailed quantification of phosphorene’s structural flexibility, interplanar P−P distances averaging 0.224 and 0.231 nm with angular fluctuations up to 10°, and the characterization of a weak yet functionally significant electrode− electrolyte interaction energy of −138.2 kJ mol−1 nm−2 that drives pronounced interfacial ionic layering. Electron density and Hartree potential profiles reveal alternating regions of charge accumulation and depletion extending ∼2.5 nm from the surface, with local electric fields reaching 108 V/m. Under zero bias, no appreciable charge transfer is observed, yet substantial local polarization effects underscore the critical role of the ionic liquid in modulating interfacial electrostatics.