Controlled-synthesis of NiS hierarchical hollow microspheres with different building blocks and their application in lithium batteries

Hierarchical hollow microspheres with nickel sulfide (NiS) nanorods as the in situ formed building blocks have been fabricated via a novel precursor hydrothermal method in alkaline solution of Na(2)S. In addition, hierarchical hollow microspheres with NiS nanoparticles as the in situ formed building blocks have also been successfully controlled-synthesized through the adjustment of experimental parameters. The NiS powders have been characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, selected area electron diffraction and high-resolution transmission electron microscopy. The reported controlled experiments allow us to propose the formation mechanism of nanorod-based NiS hierarchical hollow spheres, which involves sulfuration of Ni(OH)(2) precursors and their sequential Ostwald ripening process. When the two kinds of NiS hierarchical hollow spheres prepared herein are used as cathode materials for lithium-ion batteries, nanorod-based hierarchical hollow microspheres exhibit enhanced electrochemical properties as compared with nanoparticle-based hierarchical hollow microspheres. Electrochemical measurements have also shown that the initial discharge capacity of nanorod-based hierarchical hollow microspheres is 587.8 mAh.g(-1), which is close to the theoretical capacity of NiS (590 mAh.g(-1)). The results described in the present work may open up another way for the design of novel nanostructured materials for various applications.