A new ether-based medium-concentrated electrolyte for lithium–sulfur battery with lean Li anode

A new ether-based electrolyte with tetrahydrofuran (THF) and di-isopropyl ether (DIPE) is proposed for Lithium–Sulfur battery (LSB). By employing the common ion effect and the weakly-solvating solvent (such as DIPE), the dissolution of lithium polysulfides and the self-discharge effect are effectively inhibited. Besides, the LiFSI has be used as the co-salt in the LiTFSI-based electrolyte to improve the ionic conductivity and inhibit the side reaction on Li metal anode. It is worth mentioning that, the L1L2TD-1382 electrolyte (LiTFSI: LiFSI: THF: DIPE = 1 : 3: 8 : 2, molar ratio) ensures a stable cycling for more than 500 cycles with a high Columbic efficiency (CE) of Li deposition/stripping (>99.3%). Impressively, with selenium doped sulfurized polyacrylonitrile (SeSPAN) cathode, the Li–S cell has delivered a high capacity of 626 mAh g−1 in 500th cycle with an excellent capacity retention no less than 93%. This work provides a new insight to electrolyte design strategy of advanced electrolytes for Li–S batteries.