Robust, Ultrasmooth Fluorinated Lithium Metal Interphase Feasible via Lithiophilic Graphene Quantum Dots for Dendrite-Less Batteries.

Abstract

Dendrite growth and in-homogeneous solid electrolyte interphase (SEI) buildup of Li metal anodes hinder the longtime discharge-charge cycling and safety in secondary metal batteries. Here, the authors report an in-situ restructured artificial lithium/electrolyte SEI exposing an ultrasmooth and thin layer mediated through graphene quantum dots (GQDs). The reformed artificial interphase comprises a mixture of organic/inorganic-rich compositions alike as mosaic interphase, albeit the synergistic effect mediated via hydroxylated GQDs involving redeposition-borne lithium, and its accumulated salts, facilitate a homogeneous and ultrasmooth near fluorine-rich interfacial environment ensuring a facile lithium-ion (Li-ion) diffusion and dendritic-free nature. As a result, symmetrical graphene dots-lithium cells enable a dendrite-less operation up to 2000 h with good cycling stability and capacity retention at current densities 1 and 5mA cm-2 compared to bare lithium. The well-established fluorinated interface engenders a high reversible capacity and stable performance during the initial and long-term cycles upon configuring in lithium-sulfur (Li-S) cells. Thus, the authors' work illuminates the direction toward achieving dendritic-free smooth and robust metal anodes through manipulating and restructuring the critical SEI chemical components.