Bi-containing Electrolyte Enables Robust and Li Ion Conductive Solid Electrolyte Interphase for Advanced Lithium Metal Anodes

The notorious lithium dendrite growth, causing the safety concern, hinders the practical application of high-capacity Li metal anodes for rechargeable batteries. Here, a robust and highly ionic conductive solid electrolyte interphase (SEI) layer to protect Li metal anode is in-situ constructed by introducing trace additive of tetrapotassium heptaiodobismuthate (K4BiI7) into electrolyte. The K4BiI7-added electrolyte enables Li metal anode to display a stable cycling for over 600 cycles at 1.0 mA cm−2/1.0 mAh cm−2 and over 400 cycles at 5.0 mA cm−2/5.0 mAh cm−2. In situ optical microscopy observations also conform the suppression of Li dendrites at high current density. Moreover, the in-situ SEI layer modified Li anode exhibits an average Coulombic efficiency of 99.57% and less Li dendrite growth. The Li-S full sells with the modified electrolyte also show improved electrochemical performance. This research provides a cost-efficient method to achieve a highly ionic conductive and stable SEI layer toward advanced Li metal anodes.