Non-template synthesis of nitrogen-doped carbon-coated CoS2 nanoparticles for enhanced long-term lithium storage

The significant volume change and low conductivity are the primary challenges to effectively utilizing transition metal sulfide anode materials for lithium-ion batteries. Given that, this study presents a facile non-template method for synthesizing nitrogen-doped carbon-coated CoS2 (CoS2@NC) nanoparticle composites with diverse morphologies. The morphology of the ZIF-67 precursor was controlled by employing different anionic salts, followed by carbonization and sulfurization processes under a nitrogen atmosphere to obtain the desired CoS2@NC composites (1-3 μm). The hollow CoS2@NC (H-CoS2@NC) provides more buffering space, effectively releasing the stress caused by volume changes. H-CoS2@NC composites demonstrate excellent lithium storage performance when used as anode materials for lithium-ion batteries, in stark contrast to the comparatively subpar performance of the composite derived from rhombic dodecahedrons CoS2@NC (D-CoS2@NC). At 500 mA·g-1, the initial theoretical specific capacity of H-CoS2@NC reached 601.8 mAh·g-1. Furthermore, after 350 cycles, the capacity remained at 544.6 mAh·g-1, with a capacity retention rate of 90.5%, and the H-CoS2@NC retained its original morphology intact. The protection provided by the nitrogen-doped carbon material and its favorable morphology result in outstanding lithium storage performance of H-CoS2@NC electrode.