Effect of ether medium in LiTFSI and LiFSI-based liquid electrolytes for lithium–sulfur batteries

Abstract

Liquid battery electrolytes are utilized in most battery systems to date as they provide improved electrode contact and ionic conductivity compared to solid electrolytes; however, they pose major challenges regarding safety. Being highly flammable, toxic, and volatile, leakage of such a liquid electrolyte is always considered a major safety risk. Hence, the improvement of liquid electrolytes remains an important goal, especially for high gravimetric energy battery systems like the lithium–sulfur battery (LSB), which is considered a suitable battery type to enable fully electric-powered aviation. Here, a study on the effects of a variation of the electrolyte media and salt was conducted to establish an inexpensive alternative liquid electrolyte system to the state-of-the-art DOL/DME electrolyte of LSB. The combination of DEGMEE and LiFSI led to the best cycling performance showing an increase in cycling stability (110 cycles at 97% Coulombic efficiency) and specific capacity (~500 mAh g⁻¹ in the 110th cycle) at a moderately high C-rate of 0.25 C, which for our coin cell system translates to a moderate current of ~1.8 mA (~1.2 mA cm⁻²).