Regulating Anions in the Solvation Sheath of Lithium\nIons for Stable Lithium Metal Batteries

Abstract

Safe\nlithium (Li) metal batteries have been plagued by dendrite\ngrowth due to a heterogeneous solid electrolyte interphases (SEI)\non the Li metal anode. Modulating the solvation sheath of Li ions\nenhances the uniformity and stability of SEI significantly. However,\nanion regulation in the solvation sheath for constructing stable SEI\nis rarely touched. Herein, the solvation structure of original bis­(fluorosulfonyl)­imide\n(FSI^–) anions in the solvation sheath is altered\nby introduction of other anions, promoting the complete decomposition\nof FSI^– and forming a stable SEI on the Li metal\nanode. Moreover, both the oxidation stability window of the electrolyte\nand current collector protection were enhanced. Furthermore, the components\nand structure of the solvation sheath were disclosed by combining ¹⁷O nuclear magnetic resonance and molecular dynamics simulations.\nThis work provides fresh insight into the interrelation among various\nanions on regulating the solvation sheath of Li ions and demonstrates\nguidance in rationally designing electrolytes for stable and safe\nLi metal batteries.