Anion-derived solid electrolyte interphase realized in usualconcentration electrolyte for Li metal batteries

Constructing anion-derived solid electrolyte interphase(SEI)by recruiting anions into the solvation sheath of Li+is extremely conducive to restrain the dendrite growth of Li metal anode.However,the presence of anions in the solvation sheath of Li+is severely hindered by the solvents with strong coordinating ability in conventional electrolyte.Herein,we boost the content of anions in the primary solvation sheath of Li+by employing a solvent with low donor number,2-methyltetrahydrofuran,inducing an anion-derived SEI.As a result,the Li||Cu cells show a high average Coulombic efficiency(>99%)over 500 cycles and the Li||LiFePO4 cells under a low negative/positive capacity ratio of 2:1 exhibit an impressive capacity retention of 90%after 100 cycles.This work provides insights on constructing stable anion-derived SEI and offers guidance in designing electrolytes for stable Li metal batteries.