Improved lithium ion battery performance by mesoporous Co3O4 nanosheets grown on self-standing NiSix nanowires on nickel foam

Abstract

Novel three-dimensional (3D) hierarchical NiSi_x/Co₃O₄ core–shell nanowire arrays composed of NiSi_x nanowire cores and branched Co₃O₄ nanosheet shells have been successfully synthesized by combining chemical vapor deposition and a simple but effective chemical bath deposition process followed by a calcination process. The resulting hierarchical NiSi_x/Co₃O₄ core–shell nanowire arrays directly serve as binder- and conductive-agent-free electrodes for lithium ion batteries, which demonstrate remarkably improved electrochemical performances with excellent capacity retention and high rate capability on cycling. They can maintain a stable reversible capacity of 1279 mA h g⁻¹ after 100 cycles at a current density of 400 mA g⁻¹ and a capacity higher than 340 mA h g⁻¹ even at a current density as high as 8 A g⁻¹. Such superior electrochemical performance of the electrodes made by directly growing electro-active highly porous Co₃O₄ on a nanostructured NiSi_x conductive current collector makes them very promising for applications in high-performance lithium ion batteries.