Preparation and performances of highly porous layered LiCoO2 films for lithium batteries

Layered lithium cobalt oxide (LiCoO2) cathode films were successfully deposited onto an aluminum substrate with a large surface area by electrostatic spray deposition (ESD). Highly porous films were prepared by ESD using cobalt acetate tetrahydrate (CoOAc) and lithium hydroxide monohydrate (LiOH) dissolved ethyl alcohol (15 vol.%) and di(ethylene glycol)butyl ether (85 vol.%) as a precursor solution. An LiCoO2 film, the crystal structure of which contained a combination of layered and spinel regions, was synthesized by heat treatment for 2 h at 400 °C. Charge–discharge curves showed that the capacity of this film was 120 mAh g−1. Heat treatment at 650 °C was shown to be a low enough temperature for the resulting film to be used with an aluminum substrate and to allow the retention of the morphology of the surface on which the film is deposited. The discharge capacity for the layered LiCoO2 region of this film was 140 mA g−1 at a rate of 1C and it achieved a good cycle and a rate performance without the need for auxiliary materials.