In-situ construction of multifunctional interlayer enabled dendrite-free garnet-based solid-state batteries

Garnet-based Li6.5La3Zr1.5Ta0.5O12 (LLZTO) is a prospective solid-state electrolyte with fast ionic mobility and distinguished chemical/electrochemical stabilities toward Li metal. However, Li dendrite propagated within LLZTO bulk is one of the main obstacles to the practical application of solid-state batteries. Herein, we propose to inhibit Li dendrite growth through in-situ construction of a multifunctional interlayer of Li2S/LiSn alloy achieved via a conversion reaction of SnS layer coated on the surface of the LLZTO pellet. DFT calculation reveals that the interfacial contact of LLZTO and Li is considerably improved via Li2S/LiSn interlayer, consequently contributing to a low interfacial impendence (5.1 Ω cm2). Furthermore, the electronic insulativity of LLZTO is also meliorated to suppress electron tunneling. As a result, with effectively restraining the Li dendrite, the Li|[email protected]2S/LiSn|Li symmetrical battery exhibits a superb long-term Li plating/stripping performance over 1500 h and 700 h under 0.2 and 0.4 mA cm−2, respectively. Furthermore, the LFP|[email protected]2S/LiSn|Li full battery displays notable cycling performance (99.8% capacity retention after 100 cycles at 1 C) and rate properties (160.6 mAh g−1 at 0.1 C and 116.3 mAh g−1 at 1 C). This facile and effective method may provide a feasible strategy for eliminating the interfacial issue and achieving dendrite-free solid-state Li metal batteries.