Coupling a 3D Lithophilic Skeleton with a Fluorine-Enriched Interface to Enable Stable Lithium Metal Anode.

Abstract

Lithium (Li) metal anode is known as a potential anode candidate for next-generation high-energy-density rechargeable batteries. Nevertheless, the challenge caused by the uncontrollable Li dendrites' growth and the fragile solid electrolyte interface (SEI) layer seriously hinders the commercial application of Li metal batteries. Herein, we report a fluorine-enriched nitrogen-doped hollow carbon spheres decorated carbon fibers (FNCS@CF) skeleton which effectively integrates the uniformly distributed lithophilic sites and mechanically robust LiF-enriched SEI, thus endowing the composite Li metal anode with durable and dendrite-free features. The Li nucleation barrier is greatly reduced owing to the strong lithiophilicity characteristics of pyridinic/pyrrolic nitrogen. The fluorinated hollow carbon spheres can not only provide a powerful setting for Li deposition but can also promote the in situ formation of LiF-enriched SEI. As a result, the prepared FNCS@CF skeleton demonstrates excellent electrochemical performances such as ultrahigh average Coulombic efficiency of 99.6% over 240 cycles at 3 mA h cm-2 and remarkable cyclability (1300 h) with a low deposition overpotential of 10 mV. Furthermore, a FNCS@CF-Li|NCM full cell was also assembled which exhibits a prominent cycling stability and capacity retention even under simulated practical working conditions, i.e., low negative-to-positive capacity (N/P) ratio of 1.5 and lean electrolyte of 10 uL mAh-1.