Single-ion conducting artificial solid electrolyte interphase layers for dendrite-free and highly stable lithium metal anodes

Abstract

Lithium metal anodes are regarded as “Holy Grail” anode materials, due to their ultrahigh theoretical capacity, low redox potential and low density. However, native solid electrolyte interphases (SEIs) generated from reactions of lithium metals with electrolytes are unstable and easily destroyed by huge volume change during cycling, giving rise to side reactions and lithium dendrites. We designed and fabricated a single-ion conducting artificial SEI layer for high-performance lithium metal anodes. A LiBAMB-PETMP (LP) SEI layer was prepared by a thiol-ene click reaction on lithium metal, forming a three dimensional (3D) cross-linked network structure. BAMB anions are covalently bonded in this 3D cross-linked network, achieving single-ion conduction. This BAMB anion network can guide lithium ions to uniformly distribute and deposit. Its high ionic conductivity and unity lithium ion transference number can eliminate anion depletion-induced strong electric fields on the anodes to prevent the nucleation of dendrites. The LP SEI layer is both chemically and mechanically stable during cycling and protects lithium metal from corrosion by electrolytes. Stable lithium plating/stripping at an ultrahigh current density of 8.0 mA cm⁻² is achieved for 992 h. The innovative strategy of single-ion conducting artificial SEI layer design is promising for application in lithium metal anodes.