Highly Stable Passivation Layer on Metallic Lithium for High-Energy Rechargeable Batteries

摘要

Lithium metal is an attractive anode material for rechargeable batteries due to its extremely high theoretical specific capacity (3860 mA h g~(-1)), low density (0.59 g cm~(-3)) and highest negative reduction potential (-3.040 V vs. S.H.E.). Unfortunately, lithium metal itself faces many problems including inhomogeneous lithium deposition, infinite volume expansion, increased polarization, and dendrite formation. To overcome these drawbacks, several methods have been studied such as the use of an artificial solid electrolyte interphase (SEI) layer, and electrolyte additives. However, the electrolyte additives are continuously consumed during cycling and thus affect the electrochemical performance. Herein, we use the imidazolium-based ionic liquid in order to passivate the metallic lithium. This can lead to the stable and uniform SEI formation through Li stripping and plating. To achieve fundamental understanding, reactive molecular dynamic simulation (Reaxff) has been used to investigate the mechanism and compositions of the passivation layer compounds. The predicted compounds relate and even control to the cell performances of Li metal batteries.