Lithium sulfur batteries with compatible electrolyte both for stable cathode and dendrite-free anode

Abstract

Because of high theoretical energy density and low cost, lithium-sulfur (Li-S) batteries possess great promise for next-generation energy storage and conversions. However, their adoption is plagued by poor cycle life due to the electrochemical instability of electrodes. Here, we apply a promising fluoroethylene carbonate (FEC)-based electrolyte for Li-S batteries to fully exploit its compatibility with both sulfur composite cathode and lithium anode. Li-S batteries maintain ultra-stable cycling (capacity retention of 96.3% over 4000 times at 6 C). The Coulombic efficiency of lithium plating/stripping approaches 98.1% and Li symmetrical cells show stable cycling for 2450 h at 1.0 mA cm−2 and 1350 h at 2.0 mA cm−2. Furthermore, high-loading Li-S batteries deliver stable capacity of 7.7 mAh cm−2 without polysulfide dissolution. The excellent electrochemical performances are attributed to the elastic and robust solid electrolyte interphases both at sulfur composite cathode and lithium metal anode. This work provides an alternative direction to obtain high-energy-density Li-S batteries for commercial availability.