High-voltage nickel-rich layered cathodes in lithium metal batteries enabled by a sulfolane/fluorinated ether/fluoroethylene carbonate-based electrolyte design

Electrolyte system with high electrochemical stability and interfacial compatibility is essential to the highperformance lithium metal battery. Herein, we introduce an electrolyte design of 1 M Lithium bistrifluoromethosulfonimide (LiTFSI) sulfolane/1,1,2,2-Tetrafluoroethyl 2,2,3,3-Tetrafluoropropyl Ether (HFE)/Fluoroethylene carbonate (FEC) to improve the high voltage performance (4.7 V) for LiNi0.8Mn0.1Co0.1O2 based lithium metal batteries. Such a designed electrolyte exhibits a high-voltage limit of 5.1 V,compared to 4.3 V of the carbonated-based electrolyte (1 M Lithium hexafluorophosphate (LiPF6) ethylene carbonate(EC)/dimethyl carbonate (DMC)/ethyl methyl carbonate (EMC) 1:1:1). The cell with the designed electrolyte improves the coulombic efficiency, rate and cycle capability. The cell with the designed electrolyte delivers a reversible capacity of -220 mAh g-1 at 0.1C, with a capacity retention of -85% after 150 cycles (0.5C charge/discharge, 3.0-4.7 V), while the commercial electrolyte only exerts a capacity retention of 71.60%. X-Ray Powder Diffraction (XRD),Scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS) analysis reveal the designed electrolyte effectively improve the structural and interfacial stability on cathode. It also suppresses the lithium-dendrite growth and facilitates the stable lithium-plating/stripping on lithium metal anode. While the carbonate-based electrolyte forms thick and unstable interface on cathode and grows dendrite -liked surface on lithium anode.

Automated summary

The designed electrolyte shows excellent performance in high-voltage lithium metal batteries, improving coulombic efficiency, rate, and cycle capability. Research indicates that the electrolyte effectively enhances structural and interfacial stability on the cathode, suppressing lithium dendrite growth and facilitating stable lithium plating/stripping processes.