In Situ‐Formed LiF‐Rich Multifunctional Interfaces toward Stable Li10GeP2S12‐Based All‐Solid‐State Lithium Batteries

Abstract Li 10 GeP 2 S 12 (LGPS) solid electrolyte with extremely high ionic conductivity is a promising candidate for all‐solid‐state lithium batteries. However, continued LGPS reduction at Li/LGPS interface is huge challenge. Thus, developing a simple and effective strategy to improve Li/LGPS interfacial stability is highly urgent. Herein, LiF‐rich multifunctional interfaces on Li metal (Li@LiF), consisting of three functional components of LiF, carbon particles, and thin CF bond top‐layer, are in situ constructed on the Li metal surface by spontaneous reaction between Li metal and poly(tetrafluoroethylene) at room temperature. LiF, as the main component, significantly suppresses the interfacial reaction due to low electronic conductivity and promotes smooth lithium plating on the Li metal surface arising from high interfacial energy against Li. Meanwhile, carbon particles with excellent Li + affinity and thin strong polar CF bond top‐layer enable homogenous Li + flux as well as fast Li + migration across the LiF‐rich interface, respectively. Consequently, the LGPS‐based symmetric lithium cell possesses significantly prolonged cycling stability and increased critical current density. The LGPS‐based all‐solid‐state lithium cells employing LiCoO 2 cathode and Li@LiF anode exhibit excellent rate capability and impressive cycling stability, achieving a high capacity retention of 80.9% over 300 cycles at 0.1 C under 25 °C.