A Synergistic Strategy for the Development of Advanced, Scalable Lithium-Sulfur Batteries.

Lithium-sulfur (Li-S) batteries are identified as one of the most promising next-generation battery technologies. However, commercialization of Li-S batteries has not been widespread due to severe technical challenges, such as lithium polysulfide dissolution and shuttling inherent to the battery chemistry. In this work, we demonstrate a strategy of integrating a nanoengineered sulfur cathode with a functionalized electrolyte to overcome some of the major technical barriers and realize the high specific capacity and high-performance potentials of Li-S batteries. The nanoengineered sulfur cathode, architectured by applying an ultrathin film of nanolayer-polymer-coated-carbons on a sulfur electrode, is able to achieve a high discharge specific capacity of ∼1600 mAh/g, approaching sulfur's theoretical specific capacity of 1672 mAh/g, due to the increased redox kinetics and the PS-trapping power. The functionalized electrolyte is designed by utilizing, for the first time, 2,2,3,3-tetrafluoro-1,4-dimethoxybutane (FDMB) as a cosolvent in the Li-S electrolyte, which helps maintain the high specific capacity over extended cycles due to the strong PS-trapping power enabled by FDMB. This strategy rendered not only the highest possible specific discharge capacity but also an unprecedented cycle stability (90% capacity retention after 500 cycles at 1 C rate) in the resultant Li-S batteries. The unprecedented level of performance, along with the near-theoretical high specific capacity, was realized without using complex processes and costly materials. The synergistic strategy used in this work represents a significant advancement of the Li-S battery technology, with unprecedented high specific capacity, which can render high energy density, robust cycle life, and enhanced safety, toward commercialization.