Flexible Artificial Solid Electrolyte Interphase Formed by 1,3-Dioxolane Oxidation and Polymerization for Metallic Lithium Anodes

Lithium–tin (Li–Sn) alloys are perfect substrate materials for anodes in high-energy density lithium metal secondary batteries. A new approach is proposed to further prevent the Li deposit on Li–Sn alloy substrates from reaction with electrolytes using an artificial solid electrolyte interphase (ASEI) based on electrochemical oxidation and polymerization of 1,3-dioxolane precursor with LiTFSI additive. This ASEI layer is flexible, stable, ion conductive, and electrically insulating, which can provide very stable cycling of Li–Sn alloy substrate anodes for Li deposition/stripping with an average Coulombic efficiency of 98.4% at a current density of 1 mA cm–2. The Li–Sn alloy substrate is kept uniform and smooth without any dendrites and cracks after cycles. When the Li–Sn alloy substrate protected by ASEI is used as the anode of lithium–sulfur full cell, the cell shows much higher discharge capacity and better cycleability. This innovative and facile strategy of ASEI formation demonstrates a new and promising approach to the solution of the tough problems of Li dendrites in Li metal batteries.