Molecular Dynamics of Heteroatom-Doped Graphene Electrodes and Hybrid Electrolytes for High-Performance Ionic Liquid Supercapacitors.

Electric double-layer capacitors (EDLCs) are advanced electrochemical devices for energy storage and have attracted strong interest due to their outstanding properties. The energy storage properties are closely related to the electrode/electrolyte interface interaction. The microstructure of the electrode surface can make a significant impact on the EDL structure. Here, we investigated boron (B), nitrogen (N), and sulfur (S) doping in graphene electrodes coupled with ionic liquid (IL) electrolytes using molecular dynamics (MD) simulations under the constant potential method (CPM). The results show that heteroatom N-doping elevates ionic conductivity by 15 mS/cm compared to pristine graphene, driven by weakened electrode-solvent interactions, with the ethanol diffusivity enhanced 36%. Notably, B-doped graphene achieves a superior double-layer capacitance (CD) of 7.75 μF/cm2 within a -1 to 2 V window, attributed to additional charge storage sites and hole carrier injection that modify the electronic structure. These results demonstrate that heteroatom doping can regulate both electronic properties and interfacial dynamics, thereby mitigating the energy-power trade-off. Our work advances the molecular-level understanding of EDLCs and provides a foundation for exploring heteroatom doping strategies to design high-performance graphene-based supercapacitors.