Suppressing the Shuttle Effect and Dendrite Growth in Lithium-Sulfur Batteries.

Abstract

Practical applications of lithium-sulfur batteries are simultaneously hindered by two serious problems occurring separately in both electrodes, namely, the shuttle effects of lithium polysulfides and the uncontrollable growth of lithium dendrites. Herein, to explore a facile integrated approach to tackle both problems as well as guarantee the efficient charge transfer, we used two-dimension hexagonal VS2 flakes as the building blocks to assemble nanotowers on the separators, forming a symmetrical double-side-modified polypropylene separator without blocking the membrane pores. Benefiting from the "sulfiphilic" and "lithiophilic" properties, high interfacial electronic conductivity, and the unique hexagonal tower-form nanostructure, the D-HVS@PP separator not only guarantees the effective suppression of the lithium polysulfide shuttle and the rapid ion/electron transfer but also realizes uniform and stable lithium nucleation and growth during cycling. Hence, just at the expense of an 11% increase in the separator weight (0.14 mg cm-2), the D-HVS@PP separator delivers an over 16 times higher initial areal capacity (8.3 mAh cm-2) than a conventional PP separator (0.5 mAh cm-2) under high sulfur-loading conditions (9.24 mg cm-2). Even when used under a low electrolyte/sulfur ratio of 4 mL g-1 and a practically relevant N/P ratio of 1.7, the D-HVS@PP separator still enabled stable cycling with a high cell-level gravimetric energy density. The potentials in broader applications (Li-S pouch battery and Li-LiFePO4 battery) and the promising commercial prospect (large-scale production and recyclability) of the developed separator are also demonstrated.