Separator engineering toward suppressed shuttle effect and homogenized lithium deposition in lithium−sulfur batteries

Abstract

Lithium−sulfur (Li−S) batteries are ideal energy storage devices due to their high energy density (2600 Wh kg−1), but polysulfide shuttling and lithium dendrite growth seriously preclude their practical application. Herein, a multifunctional layer composed of MnO, MnWO4 and carbon black (CB) is constructed to modify the polypropylene separator (MnO-MnWO4/CB@PP) of Li−S batteries. The MnO-MnWO4/CB layer possesses the ability to adsorb polysulfides through physical and chemical adsorption mechanisms, as well as catalyze their conversion. Results show that the adsorption-catalysis characteristic of MnO-MnWO4/CB enhances the capture capability for polysulfides to suppress its shuttling. Moreover, it acts as a buffer layer, facilitating the parallel electrodeposition of Li and inhibiting the growth of Li dendrite. As a result, the Li/Li symmetrical cell with MnO-MnWO4/CB@PP enables durable Li plating/stripping over 8000 h at 1.0 mA cm−2 with a capacity of 1.0 mAh cm−2. In addition, the Li−S battery with this modified separator demonstrates a competitive initial capacity of 1527.7 mAh g−1 at 0.2 C and a capacity retention of 80.8% after 1000 cycles at 2.0 C. This work presents an effective and straightforward approach for designing separator of Li−S battery.