Flexible and stable 3D lithium metal anodes based on self-standing MXene/COF frameworks for high-performance lithium-sulfur batteries

Lithium metal (Li) is believed to be the ultimate anode for lithium-ion batteries (LIBs) owing to the advantages of high theoretical capacity, the lowest electrochemical potential, and light weight. Nevertheless, issues such as uncontrollable growth of Li dendrites, large volume changes, high chemical reactivity, and unstable solid electrolyte interphase (SEI) hinder its rapid development and practical application. Herein a stable and dendrite-free Li-metal anode is obtained by designing a flexible and freestanding MXene/COF framework for metallic Li. COF-LZU1 microspheres are distributed among the MXene film framework. Lithiophilic COF-LZU1 microspheres as nucleation seeds can promote uniform Li nucleation by homogenizing the Li+ flux and lowering the nucleation barrier, finally resulting in dense and dendrite-free Li deposition. Under the regulation of the COF-LZU1 seeds, the Coulombic efficiency of the MXene/COF-LZU1 framework and electrochemical stability of corresponding symmetric cells are obviously enhanced. Li-S full cells with the modified Li-metal anode and sulfurized polyacrylonitrile (S@PAN) cathode also exhibited a superior electrochemical performance.