Lithiophilic SnF2 modification on carbon fiber cloth enabling uniform Li deposition for stable lithium metal anodes

Abstract

Lithium metal has been considered as the most attractive anode candidate for high-energy-density rechargeable batteries. Nevertheless, its infinite volume change and uncontrollable dendrite growth still pose a significant challenge for practical application. Herein, lithiophilic SnF2 modification on carbon fiber cloth is rationally designed to in situ form Li-Sn alloy active sites and LiF protective layer (named as Li/Li-Sn/CF electrode). The Li-Sn alloy with high ionic diffusion coefficient endows fast kinetics for homogeneous Li transfer and eliminates the random dendrite nuclei, as well as subsequently facilitates the uniform Li deposition. The LiF protective layer on the electrode can not only isolate the active Li from the electrolyte and retard the parasitic reactions, but also inhibit the dendrite growth and stabilize solid-electrolyte interphase (SEI) film due to its electronic insulative property and excellent mechanical strength. Furthermore, stabilized by the 3D carbon skeleton, the electrode can accommodate large volume variation during long-term galvanostatic cycling. Benefiting from these merits, the symmetric cell of Li/Li-Sn/CF exhibits a stable overpotential about 25 mV for over 1000 h at a current density of 1 mA cm−2 with a fixed areal capacity of 1 mA h cm−2. Impressively, the Li/Li‐Sn/CF||LFP full cells also achieve superior cycling stability and improved rate performance.