Embedding Cobalt Atom Clusters in CNT-Wired MoS2 Tube-in-Tube Nanostructures with Enhanced Sulfur Immobilization and Catalyzation for Li-S Batteries

Lithium-sulfur batteries are one of the most promising next-generation energy storage systems. The efficient interconversion between sulfur/lithium polysulfides and lithium sulfide is a performance-determining factor for lithium-sulfur batteries. Herein, a novel strategy to synthesize a unique tube-in-tube CNT-wired sulfur-deficient MoS2 nanostructure embedding cobalt atom clusters as an efficient polysulfide regulator is successfully conducted in Li-S batteries. It is confirmed that encapsulating MWCNTs into hollow porous sulfur-deficient MoS2 nanotubes embedded with metal cobalt clusters not only can accelerate electron transport and confine the dissolution of lithium polysulfide by physical/chemical adsorption, but also can catalyze the kinetics of polysulfide redox reactions. Based on DFT calculations, in situ spectroscopic techniques, and various electrochemical studies, catalytic effects of CNT/MoS2-Co nanocomposite in Li-S battery are deeply investigated for the first time. The CNT/MoS2-Co composite cathode exhibits a very remarkable rate capability (641 mAh g(-1) at 5.0 C) and excellent cycling stability (capacity decay rate of 0.050% per cycle at 5.0 C) even at high sulfur mass loading of 3.6 mg cm(-2). More crucially, CNT/MoS2-Co tube-in-tube nanostructures present a superior specific capacity of 650 mAh g(-1) in a Li-S pouch cell at 0.2 C (4.0 mg cm(-2)).

Automated summary

Using CNT/MoS2-Co composite materials in lithium-sulfur batteries can enhance battery performance, including improved rate capability and cycling stability, while achieving high specific capacity. The composite material achieves excellent battery performance by accelerating electron transport and catalyzing polysulfide reactions, among other mechanisms.