An Alternative Electrolyte Based on Sebaconitrile for Thermally-Stable Lithium-Ion Batteries

Abstract

Volatile, flammable carbonate-based liquid electrolytes, although they show good electrochemical performance suitable for practical use, have posed a critical threat to safeties of lithium-ion batteries. This safety concern becomes more serious in newly-emerging application fields such as (hybrid) electric vehicles and grid scale energy storage systems, which employ large-sized, high-capacity lithium-ion batteries. One promising solution to address the liquid electrolyte-induced safety issues is to replace with nonflammable, thermally-stable electrolytes. Here, we demonstrate a new electrolyte system composed of 1M LiTFSI (lithium bis-trifluoromethanesulphonimide) in sebaconitrile (SBN). The SBN is featured with high boiling temperature (~ 375 oC) and nonflammability, which are expected to enable significant improvements in high-temperature performance of SBN-based electrolytes. Based on the characterization of thermal/electrochemical properties of SBN-based electrolytes, their application to lithium-ion batteries is explored as a function of operating temperature. Notably, the cell incorporating SBN-based electrolytes show stable cycling performance at 80 oC. This advantageous effect of SBN-based electrolytes on thermal stability of cell, in comparison to conventional carbonate-based liquid electrolytes, is discussed by scrutinizing the variation in AC impedance of cells and ionic conductivity of the electrolytes as a function of temperature.