CF4 Plasma-Generated LiF-Li2C2 Artificial Layers for Dendrite-Free Lithium-Metal Anodes

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 Li2C2 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 Li2C2 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-Li2C2 artificial layers provide new routes for constructing environment-friendly and high-performance energy storage devices.

Automated summary

In this study, a CF4 plasma treatment is used to modify the surface of lithium anodes, leading to the fabrication of an artificial layer consisting of LiF and Li2C2. This layer enables stable and dendrite-free lithium structures, ensuring good cycling stability and rate performance. The plasma-treated lithium exhibits stable operation for extended periods of time and when paired with a LiFePO4 cathode, delivers high reversible capacity and cycling stability.