Large-scale synthesis of aligned Co3O4 nanowalls on nickel foam and their electrochemical performance for Li-ion batteries

We first report the successful synthesis of large-scale vertically aligned single crystalline Co3O4 nanowalls grown directly on nickel foam by facile green thermal oxidation of e-beam evaporated Co thin films in static air. The resulting Co3O4 nanowalls are directly served as binder- and conductive-agent-free electrodes for lithium ion batteries and demonstrate remarkable electrochemical performance with excellent capacity retention and high rate capability on cycling due to their unique 2D nanostructure. It can retain a high reversible capacity of 835 mAh/g after 100 cycles with no capacity fading at current density of 200 mA/g and a reversible capacity up to 376 mAh/g over 20 cycles even at a current density as high as 4 A/g. Such superior electrochemical performance of the electrodes made by directly growing electro-active aligned Co3O4 nanowalls on conductive 3D nickel foam makes them have very promising applications in high-performance lithium ion batteries.