Boosting Polysulfide Transformation by NiCo2S4 Hollow Dodecahedra@Nitrogen-Doped Carbon Core/Shell Nanostructures as Cathodes for Lithium–Sulfur Batteries

Lithium–sulfur batteries are promising for high-capacity energy storage, but their performance is limited by the shuttle effect and unfavorable volume changes during the charging and discharging cycles. To address these issues, we synthesized NiCo2S4 hollow dodecahedra@nitrogen-doped carbon core/shell nanostructures (NiCo2S4@NC) using the ZIF-67 template and polydopamine carbonization. The high chemical conversion rate and large specific surface area of NiCo2S4 hollow dodecahedra promote fast and stable polysulfide conversion, while the N-doped carbon shell mitigates structural collapse and volume changes caused by reversible reactions of lithium sulfides. Coupling the superior polysulfide conversion of NiCo2S4 with the excellent polysulfide adsorption of the N-doped carbon shell, NiCo2S4@NC/S (72% sulfur loading) delivers an initial specific capacity of 1170 mA h g–1 at 0.2 C, a capacity retention of 61% after 300 cycles, and a reversible specific capacity of 420 mA h g–1 after 500 cycles at a high current density of 1 C. Our results suggest that NiCo2S4@NC can serve as a promising cathode material for lithium–sulfur batteries with improved performance and stability.