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

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).