Studies on the morphologies of LiCoO 2 films prepared by soft solution processing

Abstract

Lithium cobalt oxide films were prepared on nickel plates and foam nickel by soft solution processing method. The films were characterized by chemical analysis, X-ray diffraction, scanning electron microscopy, and atomic force microscopy. It was found that growth of LiCoO 2 crystal on polished nickel plates and foam nickel led to different morphologies of LiCoO 2. A compact LiCoO 2 film was formed on smooth nickel plates while some grassy LiCoO 2 crystals formed and scattered on the surface of foam nickel, which indicates different mechanism of films growth. Formation of LiCoO 2 crystal on nickel plates shows the characteristic of two-dimensional nucleation while on foam nickel shows the characteristic of preferential nucleation. Further, increase of LiOH concentration in the soft solution results in morphological change of LiCoO 2 film from hexagonal platelets to spherical grains. In addition, the larger the current density, the less the grain size and the porosity inside grains are.