Improved lithium ion battery performance by mesoporous Co₃O ₄ nanosheets grown on self-standing NiSi_x nanowires on nickel foam

Novel three-dimensional (3D) hierarchical NiSi_x/Co ₃O₄ 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/Co ₃O₄ 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. © 2014 the Partner Organisations.