Rational design of MoSSe nanosheets on N-doped carbon hollow spheres for accelerating polysulfide redox kinetics of high-performance lithium-sulfur batteries

Abstract

Lithium-sulfur (Li-S) batteries with high theoretical energy densities offer a promising alternative for next-generation energy storage. However, the poor conductivity, shuttle effect of lithium polysulfides (LiPSs), and large volume expansion upon cycling hinder their application. Hollow nanostructures can play an important role in achieving high sulfur loading, buffering volume expansion, and inhibiting LiPSs shuttling. In this work, MoSSe nanosheets grown on N-doped carbon hollow spheres (MoSSe/NC) are used as both sulfur host and separator to achieve catalytic adsorption and conversion of LiPSs. As a sulfur host, MoSSe/NC can enhance electron/ion transport and alleviate the volume expansion of sulfur during cycling, further accelerating the redox kinetics. The MoSSe/NC-modified separator can also induce interfacial charge modulation and expose more active sites, promoting rapid anchoring and conversion of LiPSs and uniform deposition of Li2S. Theoretical calculations and experiments verify that MoSSe/NC can catalyze the conversion of LiPSs, inhibit the shuttle effect, and effectively improve the electrochemical properties of sulfur. Therefore, the MoSSe/NC based Li-S battery exhibits high initial capacity (1455 mAh g−1), excellent rate performance (891 mAh g−1 at 2 C), and good cycling stability (0.049% capacity decay rate at 800 cycles at 1 C).