Electrostatic spray deposition of nanoporous CoO/Co composite thin films as anode materials for lithium-ion batteries

Cobalt alkoxide suspension is obtained by heating a mixed polyalcohol solution of cobalt acetate in an oil bath at 170 °C. Thermogravimetric analysis is adopted to determine the chemical formula of the alkoxide powder in the suspension. With the suspension precursors, CoO/Co composite thin films are fabricated by electrostatic spray deposition and subsequent heat treatment in nitrogen. They are characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. Electron energy loss spectroscopy mapping is applied to determine the lateral two-dimensional chemical distribution of metallic Co in the nanocomposites. The thin film can deliver a high reversible capacity of 1182.1 mAh g−1 at 70th cycle and retain 69.5% of the initial capacity at 10C. The in situ production of metallic cobalt and the unique hollow structure of the particles can account for the good electrochemical performance.