Stabilize lithium metal anode through in-situ forming a multi-component composite protective layer

Abstract Lithium (Li) metal anode is regarded as the “Holy Grail” due to its high theoretical specific capacity and low electrochemical redox potential. However, the poor battery life and serious safety concerns caused by uncontrolled growth of Li dendrites and the extreme instability of the interface during long-term Li plating/striping process have always been obstacles to the commercialization of Li metal batteries (LMBs). Herein, a multi-component composite protective layer (MCPL) consisted of Li-Zn alloy, LiBr and organic products for stabilizing Li metal anode is prepared by multiple chemical reactions on Li metal anode. Under the protection of this artificial protective layer, the modified Li metal anode reduces the risk of excessive corrosion by electrolyte, and keeps the Li plating/striping cycle under a stable interface, which greatly reduces the formation of Li dendrites and the volume expansion effect. As a result, the symmetric Li/Li battery with multi-component composite protective layer shows better cycling stability at the current density of 0.5 mA cm−2 with a super-flat voltage plateau for about 4000 h. More importantly, the Li/Li4Ti5O12 full batteries show superior C-rate performance and higher capacity retention rate of 85.2% after 1000cycles at 1.0C. Furthermore, MCPL can effectively alleviate air corrosion, greatly reducing assembly and storage risks. This work provides a simple and effective method for achieving safe LMBs by designing a reasonable multi-component composite artificial protective layer.