A Mixed Ether Electrolyte for Lithium Metal Anode Protection in Working Lithium-Sulfur Batteries

Lithiumsulfur (Li-S) battery is considered as a promising energy storage system to realize high energy density. Nevertheless, unstable lithium metal anode emerges as the bottleneck toward practical applications, especially with limited anode excess required in a working full cell. In this contribution, a mixed diisopropyl ether-based (mixed-DIPE) electrolyte was proposed to effectively protect lithium metal anode in Li-S batteries with sulfurized polyacrylonitrile (SPAN) cathodes. The mixed-DIPE electrolyte improves the compatibility to lithium metal and suppresses the dissolution of lithium polysulfides, rendering significantly improved cycling stability. Concretely, Li | Cu half-cells with the mixed-DIPE electrolyte cycled stably for 120 cycles, which is nearly five times longer than that with routine carbonate-based electrolyte. Moreover, the mixed-DIPE electrolyte contributed to a doubled life span of 156 cycles at 0.5 C in Li | SPAN full cells with ultrathin 50 mu m Li metal anodes compared with the routine electrolyte. This contribution affords an effective electrolyte formula for Li metal anode protection and is expected to propel the practical applications of high-energy-density LiS batteries.