Stable Anion-Derived Solid Electrolyte Interphase in Lithium Metal Batteries

High-energy-density lithium (Li) metal batteries are severely hindered by the dendritic Li deposition dictated by non-uniform solid electrolyte interphase (SEI). Despite its unique advantages in improving the uniformity of Li deposition, the current anion-derived SEI is unsatisfactory under practical conditions. Herein regulating the electrolyte structure of anions by anion receptors was proposed to construct stable anion-derived SEI. Tris(pentafluorophenyl)borane (TPFPB) anion acceptors with electron-deficient boron atoms interact with bis(fluorosulfonyl)imide anions (FSI-) and decrease the reduction stability of FSI-. Furthermore, the type of aggregate cluster of FSI- in electrolyte changes, FSI- interacting with more Li ions in the presence of TPFPB. Therefore, the decomposition of FSI- to form Li2S is promoted, improving the stability of anion-derived SEI. In working Li | LiNi0.5Co0.2Mn0.3O2 batteries under practical conditions, the anion-derived SEI with TPFPB undergoes 194 cycles compared with 98 cycles of routine anion-derived SEI. This work inspires a fresh ground to construct stable anion-derived SEI by manipulating the electrolyte structure of anions.

Automated summary

By regulating the electrolyte structure of anions using TPFPB anion acceptors, a stable anion-derived SEI was constructed to improve the stability and cycling performance of lithium metal batteries under practical conditions.