Effect of LiOH concentration change on simultaneous preparation of LiCoO2 film and powder by hydrothermal method

LiCoO2 film and powder applicable to rechargeable lithium microbatteries have been directly prepared at the same time by hydrothermal treatment of a cobalt metal plate in a concentrated LiOH solution. The effect of LiOH concentration (0.1–6 M) on the structural change in film and powder has been examined using the XRD, micro-Raman and SEM analyses. It is found that all the powders with a layered hexagonal structure are precipitated by homogeneous nucleation regardless of LiOH concentration, whereas the dependence of film structure on the concentration is revealed by a selection of phase such as cobalt hydroxide species, hexagonal or cubic spinel phases formed by heterogeneous nucleation.