Very Stable Lithium Metal Stripping-Plating at a High Rate and High Areal Capacity in Fluoroethylene Carbonate-Based Organic Electrolyte Solution

We report the highly stable galvanostatic cycling of lithium metal (Li) electrodes in a symmetrical Li|electrolyte solution|Li coin-cell configuration at a high rate and high areal capacity using fluoroethylene carbonate (FEC)-based electrolyte solutions [1 M LiPF₆ in FEC/dimethyl carbonate (DMC)]. The FEC-based electrolyte solution shows cycling behavior that is markedly better than that observed for the cells cycled with an ethylene carbonate (EC)-based electrolyte solution (1 M LiPF₆ in EC/DMC). With FEC-based electrolyte solution, Li|Li cells can be cycled at 2 mA cm^-2 with an areal capacity of 3.3 mAh cm^-2 for more than 1100 cycles, and full Li|LiNi_0.6Co_0.2Mn_0.2O₂ (NMC) cells with high areal loading cathode demonstrate stable cycling with the same capacity during 90 cycles. An increase in areal capacity up to 6 mA h cm^-2 does not affect the shape of the voltage profile of the symmetric Li|Li cells. The reason for this high performance is the formation of a stable and efficient solid electrolyte interphase (SEI) on the surface of the Li metal electrodes cycled in the FEC-based solution. The composition of the SEI is analyzed by Fourier transform infrared spectroscopy.