Improved lithium ion battery performance by mesoporous Co[sub 3]O[sub 4] nanosheets grown on self-standing NiSi[sub x] nanowires on nickel foam.

Novel three-dimensional (3D) hierarchical NiSi[sub x]/Co[sub 3]O[sub 4] core-shell nanowire arrays composed of NiSi[sub x] nanowire cores and branched Co[sub 3]O[sub 4] 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[sub x]/Co[sub 3]O[sub 4] 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[sup -1] after 100 cycles at a current density of 400 mA g[sup -1] and a capacity higher than 340 mA h g[sup -1] even at a current density as high as 8 A g[sup -1]. Such superior electrochemical performance of the electrodes made by directly growing electro-active highly porous Co[sub 3]O[sub 4] on a nanostructured NiSi[sub x] conductive current collector makes them very promising for applications in high-performance lithium ion batteries. [ABSTRACT FROM AUTHOR]