High-Performance Lithium Metal Cathode Achieved by Electrochemical Stripping of In-Situ Fluoro-Oxygen Doped Graphene

Abstract

As traditional lithium-ion batteries have been unable to meet the energy density requirements of various emerging fields, lithium-metal batteries (LMB), known for their high energy density, are considered promising next-generation energy storage batteries. However, a series of problems, including low coulombic efficiency and low safety caused by dendrites, limit lithium metal batteries’ application. Herein, Fluoro-oxygen co-doped graphene (FGO) was used to modify the copper current collector (FGO@Cu). The FGO-coated current collector provides more even nucleation sites to lower the local effective current density. FGO is partly reduced during cycling and helps form stable LiF-rich SEI. Moreover, the oxygen and fluorine functional groups of graphene reconstructs the current density distribution, promoting the uniform lithium plating. The FGO@Cu current collector shows superior properties than commercial Cu foil. The FGO@Cu delivers a 97% high CE for over 250 cycles at 1 mA cm-2. Symmetric battery cycled at 1 mA cm-2 for over 650 h. LiFePO4 Full cell with lithium-plated FGO@Cu collector as anode exhibits superior cycling stability.

Keywords: Li metal anode, Fluoro-oxygen co-doped graphene, LiF, stable SEI.