Boosting the Intrinsic Stability of Lithium Metal Anodes by an Electrochemically Active Encapsulating Framework

Abstract The lithium metal anode (LMA) is a promising technology to promote the energy density of secondary batteries. However, the coupled growth of surface corrosion and deposited lithium with high reactivity causes capacity fading and safety hazards, especially at high temperatures. Great efforts have been focused on preventing the LMA from direct contact with electrolytes to extend its lifespan, but few pay attention to its stability at high temperatures, which is crucial to battery safety. Herein, a 3D Li 22 Sn 5 ‐based interpenetrated skeleton is introduced into the bulk of LMA with mechanical kneading, which enables a LMA with fast and stable cycles at high temperatures and improved safety under thermal abuse. The Li 22 Sn 5 skeleton acts as a solid electrolyte inside the bulk, allowing rapid Li + ion transport and homogenous lithium stripping/plating into the porous bulk through Li/Li 22 Sn 5 interface. The encapsulating framework expands the electrochemically active area and limits its exposure to the electrolyte, enabling a LMA with steady cyclability even at 60 °C. Trapping lithium inside the thermally stable skeleton postpones the catastrophic exothermal reactions between lithium and electrolytes. The strategy for constructing a 3D encapsulating lithiophilic framework is promising for creating safe and stable lithium metal batteries working under harsh circumstances.