Unique Li Composite Anode with LiF on the Surface and Li-Sn Alloy Inside for Next Generation Li Metal Batteries

Lithium metal anode (LMA) is considered a promising anode with low electrochemical redox potential and ultrahigh theoretical specific capacity (3680 mAh g-1) for next-generation high-energy batteries. However, the practical usage of LMA is still limited by the uncontrolled lithium dendrite growth, huge volume expansion, and low coulombic efficiency due to inhomogeneous lithium stripping/plating and side reactions with electrolytes. In this work, a unique Li composite anode (LiF-Li-Li22Sn5@Ni) is prepared for the first time via a facile one-step thermal fusion method. The LiF-Li-Li22Sn5@Ni anode consists of LiF on the surface, with Li-Sn alloy and Ni inside. Among them, Sn serves as the lithiophilic site, which reduces the nucleation overpotential of lithium and inhibits the formation of dendrites. Ni, which is chemically inert to Li, can maintain the structural stability of the LiF-Li-Li22Sn5@Ni anode. Furthermore, the LiF on the surface can inhibit Li dendrite growth and induce uniform Li deposition. As a result, the performance of cell is remarkably improved, with more than 1500 hours of cycling in a symmetrical cell at 1 mA cm-2 for 1 hour, and a capacity retention of 88.4 % after 800 cycles for the full cell assembled with LFP.