PNNL

Abstract

Lithium (Li) pulverization during cycling is one of the most critical barriers for safe operation of Li metal batteries (LMBs). Here we report a new approach to prevent pulverization of Li during cycling using a novel electrolyte based on the fluorinated orthoformate solvent, which is the first time used in rechargeable Li batteries. This electrolyte significantly expands the electrolyte stability window and lowers the electrolyte/Li reactivity by generating a thin, uniform, compact, and robust solid electrolyte interphase on Li metal anode. It not only eliminates porous dendritic lithium formation, but also minimizes Li loss and volumetric expansion. Furthermore, it greatly suppresses the phase transformation (from layer structure to rock salt) of the cathode surface and stabilizes the cathode structure. Therefore, excellent cell performances in terms of long-term cycling stability and high rate capability can be realized in high voltage LMBs together with reduced safety concerns.