SnF-Catalyzed Lithiophilic-Lithiophobic Gradient Interface for High-Rate PEO-Based All-Solid-State Batteries.

Polyethylene oxide (PEO)-based all-solid-state lithium metal batteries (ASSLMBs) are strongly hindered by the fast dendrite growth at the Li metal/electrolyte interface, especially under large rates. The above issue stems from the suboptimal interfacial chemistry and poor Li transport kinetics during cycling. Herein, a SnF-catalyzed lithiophilic-lithiophobic gradient solid electrolyte interphase (SCG-SEI) of LiSn/LiF-LiO is in situ formed. The superior ionic LiF-LiO rich upper layer (17.1 nm) possesses high interfacial energy and fast Li diffusion channels, wherein lithiophilic LiSn alloy layer (8.4 nm) could highly reduce the nucleation overpotential with lower diffusion barrier and promote rapid electron transportation for reversible Li plating/stripping. Simultaneously, the insoluble SnF-coordinated PEO promotes the rapid Li ion transport in the bulk phase. As a result, an over 46.7 and 3.5 times improvements for lifespan and critical current density of symmetrical cells are achieved, respectively. Furthermore, LiFePO-based ASSLMBs deliver a recorded cycling performance at 5 C (over 1000 cycles with a capacity retention of 80.0 %). More importantly, impressive electrochemical performances and safety tests with LiNiMnCoO and pouch cell with LiFePO, even under extreme conditions (i.e., 100 °C), are also demonstrated, reconfirmed the importance of lithiophilic-lithiophobic gradient interfacial chemistry in the design of high-rate ASSLMBs for safety applications.