Synergistic enhancement of adsorption and catalysis of polysulfides by heterostructures of multi-metallic sulfides for lithium-sulfur batteries

The shuttle effect of lithium polysulfides (LiPSs) exerts a significant impact on the longevity of lithium‑sulfur batteries (LSBs). Here, the molybdenum‑nickel bimetallic sulfide (NiMo 2 S 4 ) is creatively synthesized and combined with (NiCo 2 S 4 ) to form a heterostructure NiCo 2 S 4 -NiMo 2 S 4 with a coral-like surface. The heterostructure combines the high conductivity of nickel‑cobalt elements and the high catalytic activity of molybdenum elements, resulting in the generation of internal electric fields at the interface between different semiconductors. This leads to an enhanced catalytic effect on LiPSs, as demonstrated by density functional theory (DFT) calculations. The material is ultimately applied in self-supporting paper-based cathode materials, demonstrating excellent electrochemical performance. It provides an initial discharge specific capacity of 1402 mA h g −1 at a current density of 0.2C, and even at a high current density of 1C, the initial discharge specific capacity remains as high as 1206 mA h g −1 . In addition, under a high sulfur loading of 7.1 mg cm −2 at 0.2C, the initial discharge specific capacity is 723 mA h g −1 , and the capacity retention rate reaches 78 % after 100 cycles. Additionally, DFT calculations confirmed the exceptional adsorption capability of this heterostructure towards LiPSs. This study provides valuable insights into the design of heterostructures and defect engineering for constructing high-performance NiCo 2 S 4 -NiMo 2 S 4 heterostructures for LSBs while enhancing our understanding of LiPSs adsorption and conversion processes.