Improving stability and reaction kinetics of CoS2 anodes by introducing NiS2 to form heterostructure for superior sodium storage

To effectively address the critical challenges of pronounced volumetric expansion and intrinsic low electrical conductivity in bimetallic sulfide anodes for sodium-ion batteries (SIBs). In this study, a cobalt-based MOF (ZIF-67) was employed as the precursor material to synthesize heterostructure CoS 2 /NiS 2 composites via a co-precipitation method and hydrothermal vulcanization process. This heterostructure design not only enhances ionic conductivity but also endows the material with exceptional cycling stability, and the well-defined hollow structure provides a high specific surface area with abundant active sites for efficient sodium storage. As a SIBs anode, the composite delivered an initial discharge capacity of 936.8 mAh g −1 at 0.1 A g −1 . After 100 cycles, it retained 704.1 mAh g −1 with 99 % Coulombic efficiency, highlighting exceptional capacity retention. Notably, at 5.0 A g −1 , the material sustained 386.6 mAh g −1 after 250 cycles, further confirming its superior sodium storage capability. This work offers a promising design strategy for advanced SIBs anodes by leveraging heterostructure engineering to simultaneously enhance stability and kinetic performance.