MXene-Modulated Garnet Electrolyte Interface for Uniform Li Flux and Dendrite-Free Solid-State Lithium Metal Batteries

Garnet-type solid electrolytes hold great promise for solid-state Li-metal batteries owing to their high ionic conductivity, large shear modulus, and excellent Li metal stability. However, their air instability and poor interfacial contact cause high Li/garnet interfacial resistance and Li dendrite growth. Herein, an ionic/electronic mixed-conductive artificial interlayer (denoted as MLPL), consisting of MXene nanosheets, Li 6.4 La 3 Zr 1.4 Ta 0.6 O 12 (LLZT) particles, and a poly(ethylene oxide)/lithium salt (PEO/LiTFSI) matrix, is fabricated at the LLZT/Li interface to address these issues. Incorporating MXene and LLZT suppresses PEO crystallization, enhances segmental motion, and efficiently boosts ionic conductivity. The as-obtained MLPL interlayer is thin (15 μm) and exhibits excellent chemical/electrochemical stability and high ionic conductivity (1.48 × 10 −4 S cm −1 at 60°C). Furthermore, it homogenizes interlayer electric field distribution, mitigates electron-induced garnet attack, improves interfacial contact, accelerates Li + transport, and suppresses dendrite growth, as confirmed by field-emission scanning electron microscopy, electrochemical measurements and COMSOL simulations. Consequently, LiFePO 4 /LLZT@MLPL/Li cells exhibit excellent rate performance (95.4 mA h g −1 at 2.0C) and cycling stability (124.2 mA h g −1 after 100 cycles at 0.1C, 135.6 mA h g −1 after 70 cycles at 0.5C, 60°C). This work offers a universal and feasible strategy for interfacial engineering toward high-performance solid-state batteries. Graphical A mixed ionic/electronic conductive MLPL interlayer stabilizes the garnet/Li interface, homogenizes the electric field, and suppresses Li dendrites for high-performance solid-state Li metal batteries.