Functionality of Dual-Phase Lithium Storage in a Porous Carbon Host for Lithium-Metal Anode

摘要

Lithium (Li) metal is regarded as the most attractive anode material for high-energy Li batteries, but it faces unavoidable challenges-uncontrollable dendritic growth of Li and severe volume changes during Li plating and stripping. Herein, a porous carbon framework (PCF) derived from a metal-organic framework (MOF) is proposed as a dual-phase Li storage material that enables efficient and reversible Li storage via lithiation and metallization processes. Li is electrochemically stored in the PCF upon charging to 0 V versus Li/Li+ (lithiation), making the PCF surface more lithiophilic, and then the formation of metallic Li phase can be induced spontaneously in the internal nanopores during further charging below 0 V versus Li/Li+ (metallization). Based on thermodynamic calculations and experimental studies, it is shown that atomically dispersed zinc plays an important role in facilitating Li plating and that the reversibility of Li storage is significantly improved by controlled nanostructural engineering of 3D porous nanoarchitectures to promote the uniform formation of Li. Moreover, the MOF-derived PCF does not suffer from macroscopic volume changes during cycling. This work demonstrates that the nanostructural engineering of porous carbon structures combined with lithiophilic element coordination would be an effective approach for realizing high-capacity, reversible Li-metal anodes.