Direct fabrication of thin-film LiNiO2 electrodes in LiOH solution by electrochemical-hydrothermal method

The formation of the ternary oxide thin films on nickel substrates in LiOH solution was studied under hydrothermal or electrochemical-hydrothermal conditions. While the purely hydrothermal treatment of nickel substrates at 150 degrees C leads to the formation of Ni(OH)(2) films, by the use of the electrochemical-hydrothermal approach under supplementary galvanostatic charge with the same hydrothermal conditions, LiNiO2 films are directly fabricated. The structural purity and chemical composition of the obtained films were confirmed by X-ray diffraction pattern analysis and X-ray photoelectron spectroscopy, respectively. The fabricated films show, according to X-ray diffraction, a good crystallinity without any post-synthesis annealing. In comparison with the fabrication of Ni(OH)(2) films by the hydrothermal method, it has been found that the electrochemical anodic process is necessary to obtain the desired LiNiO2 films.