Boosting Polysulfide Transformation by NiCo<sub>2</sub>S<sub>4</sub> Hollow Dodecahedra@Nitrogen-Doped Carbon Core/Shell Nanostructures as Cathodes for Lithium–Sulfur Batteries
Qiaodan Wu, Tong Guo, Zhenhua Wu, Kangsheng Shi, Xingke Yang, Ziqiang She, Ruiya Zhao, Yunjun Ruan
Abstract
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 NiCo 2 S 4 hollow dodecahedra@nitrogen-doped carbon core/shell nanostructures (NiCo 2 S 4 @NC) using the ZIF-67 template and polydopamine carbonization. The high chemical conversion rate and large specific surface area of NiCo 2 S 4 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 NiCo 2 S 4 with the excellent polysulfide adsorption of the N-doped carbon shell, NiCo 2 S 4 @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 NiCo 2 S 4 @NC can serve as a promising cathode material for lithium–sulfur batteries with improved performance and stability.