Bismuth-Contained Lithiophilic Protective Layer on Lithium Metal Anode In Situ Generated via Electrochemical Method

Lithium metal anode (LMA) faces the challenge of poor electrochemical performances in the exfoliation of the interfacial protective layer from the anode, which is caused by the dramatic volumetric variation of the lithium metal during cycling. In this work, a bismuth-contained lithiophilic protective layer was spontaneously formed on the Li metal by the Bi(TFSI)3 salt additive. The protective layer formed via electrochemical way is relatively dense and homogeneous with a small size of ∼38 nm Li3Bi alloy and abundant LiF. This layer shows excellent property of uniform lithium deposition and displays enough mechanical strength with the Young's modulus of ∼6 GPa to suppress Li dendrite growth and reduces the interfacial side reactions. Utilized in LiFePO4/Li cells, the cyclic performance has been improved with the retention capacity of ∼70.6% in 300 cycles.