Theoretical Insights into the Molecular Interaction in Li-Ion Battery Electrolytes from the Perspective of the Dielectric Continuum Solvation Model

Rational electrolyte design stands as a frontier in the research and development of Li-ion batteries. Nevertheless, detailed investigations about the influence of the dielectric continuum solvation model on molecular interactions are still limited. Herein, we systematically study the impacts of the dielectric constant (ε) on isolated molecules (i.e., ions and solvent molecules), isolated ion pairs, and solvation complexes via density functional theory calculations. The energy shift due to solvation cavity creation is the largest, and charged species always have larger energy shifts than neutral species. For charged species, the energy shifts gradually decrease with a decreasing proportion of Li ions and an increasing proportion of anions, while for neutral species, larger dipole moments lead to higher energy shifts. As predicted by the relative method, the energetic order of ion pairs and solvation complexes in vacuum can be dramatically changed in various dielectric continuums. Furthermore, electrochemical stability windows of charged species change dramatically with ε, while those of neutral species stay almost constant. By clarifying the impacts of dielectric continuum solvation on molecular interactions, we hope to set a benchmark for the molecular interaction calculation, which is critical for the rational design of electrolytes in Li-ion batteries.