Lithium metal anodes have long been considered as "holy grail" in the field of energy storage batteries, but dendrite growth and large volume changes hinder their practical applications. Herein, a facile and eco-friendly CF4 plasma treatment is employed for the surface modification of Li anodes, and an artificial layer consisting of LiF and Li2 C2 is fabricated for the first time. Experimental results and theoretical calculations reveal that the high adsorption energy of LiF and low Li+ diffusion barriers in Li2 C2 induce uniform nucleation and planar growth of Li, guaranteeing a stable and dendrite-free Li structure during the repeated plating/stripping process of cycling. Symmetric cells using CF4 plasma-treated Li operate stably for more than 6500 h (at 2 mA cm-2 and 1 mAh cm-2 ) or 950 h (at 1 mA cm-2 and 10 mAh cm-2 ). When paired with a LiFePO4 cathode, full batteries deliver a high reversible capacity of 136 mAh g-1 (at 1 C) with considerable cycling stability (97.2% capacity retention over 200 cycles) and rate performance (116 mAh g-1 up to 5 C). This powerful application of plasma technology toward novel LiF-Li2 C2 artificial layers provide new routes for constructing environment-friendly and high-performance energy storage devices.
Keywords: CF4 plasma; LiF-Li2C2 artificial layer; dendrite-free; lithium metal anodes.
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