High Efficiency, Low Polysulfides Solubility Electrolytes for Lithium Sulfur Batteries

Abstract

Lithium-sulfur (Li-S) battery is one of the most promising next generation energy storage systems because of its high energy density, low cost and environmental benignity. 1 However, their practical application is still hindered by the severe shuttle effect of polysulfides and poor stability of lithium metal anode (LMA). 2 The electrolyte is critical to enable full potential of Li-S batteries because its formulation and structure determine the solubility of the polysulfides. It also determines properties of the solid electrolyte interphase (SEI) formed on LMA surface which acts as a kinetic barrier for the continuous reactions between the electrolyte and the LMA. 2,3 This work reports low-polysulfides-solubility electrolytes (LPSEs) for Li-S batteries, in which new solvents with low-polysulfide-solubility and good Li metal stability are used to improve the overall performance of Li-S cells. By using the optimized LPSE, the capacity retention and the Coulombic efficiency of the Li-S batteries are greatly improved compared to the cells using the conventional electrolyte adopted in Li-S batteries. In addition, the LPSE can also significantly reduce the cell self-discharge compared to the baseline electrolyte. The systematic investigations and fundamental insights into LPSEs can guide further design of advanced electrolytes for Li-S batteries. The details will be discussed during the presentation.