Lithium Nitrate as Salt Additive for Solid Electrolyte Interphase Formation in Dual-Ion Battery

Abstract

Tuning the solid electrolyte interphase (SEI) formation in dual-ion batteries is important for improving their long-term stability. In this context, salt additives have gained importance which can sacrificially undergo reduction thereby protecting the working salt. Herein, we have considered dual salt electrolyte models of LiNO3 additive with LiPF6 and LiFSI salt to carry out ab initio molecular dynamics (AIMD) simulations and witness the evolution of SEI layer. Various contact ion pair and solvent separated ion pair models of the dual salt electrolytes have been considered to further understand the role played by solvation shells of the ions. The small size and quicker diffusion of anions through the electrolyte results in its decomposition at the electrode surface irrespective of the anion being in contact ion pair or solvated by solvent molecules. Overall, along with underlining the role of salt additives in SEI formation, this detailed study also provides insights regarding the factors beyond solvation characteristics of salt that determines the SEI growth process. © 2023 Wiley-VCH GmbH.