Localized high-concentration electrolytes (LHCEs) offer a promising avenue for enhancing the versatility of electrolytes owing to their unique physicochemical properties. LHCEs are formed by diluting high-concentration electrolytes (HCEs) with antisolvents, which minimally affect the solvation structure of lithium. This study investigates the impact of 1,1,2,2-tetrafluoroethylene 2,2,3,3-tetrafluoropropyl ether (TTE) in a concentrated electrolyte system comprising bis(fluorosulfonyl)imide (LiFSI) and 1-methyl-1-propylpyrrolidinium (pyr13) on the energetics, and solvation structure of ionic liquid electrolytes (ILs). Employing density functional theory (DFT) calculations and molecular dynamics (MD) simulations, we explore the stability of lithium (Li) in varying concentrations of fluorinated ether-based additives. Our findings reveal the addition of an antisolvent reduces the free-state solvent molecules and enhances the coordination between Li+ and solvent molecules (FSI-), resulting in a significant impact on the Li+ solvation sheath. Additionally, we observe that antisolvent enhances Li-ion mobility and transport properties with minimal contribution to initiating energy barriers. Consequently, the impact of antisolvents on the physical and electrochemical behavior of solvation structures cannot be overlooked. These findings provide valuable insights into understanding the impact of various concentrations of antisolvent on solvation structures and pave a new way to improve battery performance.