In Situ Construction of a LiF/LiCl-Rich Solid Electrolyte Interphase for Lithium Ion Unimpeded Transport

Abstract

Lithium metal batteries have attracted significant research attention because of their satisfactory specific capacity and low overpotential. However, uneven Li deposition and uncontrolled dendrite growth limit the further development of this technique. In this study, we propose the addition of C 4 H 2 Cl 2 S to the electrolyte to induce Li deposition and inhibit Li dendrite growth. The additive reacts with the surface of the lithium metal anode to promote the decomposition of TFSI − anionic groups and participate in the film formation reaction, which is confirmed by density functional theory calculation and X-ray photoelectron spectroscopy results. This results in the formation of a dense and robust solid electrolyte interphase (SEI) rich in LiF/LiCl, which enhances interphase reactivity and promotes the flux distribution of lithium ions, significantly facilitating the unimpeded transport of Li + and effectively inhibiting the growth of Li dendrites. Furthermore, the excellent mechanical strength of LiF/LiCl, the key component of the SEI, effectively inhibits the SEI rupture caused by the increase in volume of lithium metal during plating/stripping. The assembled Li||Li battery exhibited a stable cycle of over 2200 h (current density: 1 mA cm −2 , deposition capacity: 1 mAh cm −2 ). In addition, the Li−S battery also showed excellent magnification performance and excellent cycle stability; after 500 cycles at 1C, the capacity remained at 659 mAh g −1 . This study provides a simple and convenient method for constructing an SEI with strong mechanical toughness and high flux to improve the cycle stability of lithium metal batteries.