Systematic Investigation of Classical Molecular Dynamics Models for Ionic Liquid‐Based Electrolytes at Electrode Interfaces

Molecular dynamics (MD) simulations are widely used to investigate ionic liquid (IL) electrolytes and their interfaces at electrified electrodes. However, the predicted interfacial nanostructure and chemistry of electrolytes are strongly influenced by methodological choices, including electrode models and force-field treatments, whose relative performance remains insufficiently understood. Here, we systematically evaluate two electrode modelling approaches: the constant charge model (CCM) and the constant potential model (CPM), together with the role of force field polarisability, for studying interfaces of IL-based electrolytes, including neat ILs, salt-containing ILs, and hybrid systems with cosolvents or mixed cations. The aim is to assess how effective these approaches capture potential-dependent interfacial structure and chemistry relevant to battery performance. For neat and salt-containing ILs, CCM and CPM with non-polarisable force fields (NPFF) generally produce consistent results on ion layering and composition, although differences in ion orientation are observed. However, hybrid IL with a cosolvent exhibit notable discrepancies in solvent behaviour. For mixed-cation ILs, additional caution is required as distinct interfacial responses emerge between NPFF and polarisable force fields (PFF) treatments. This work provides practical guidance for modelling IL-electrode interfaces and highlights the need for careful methodological choice alongside experimental validation.