FABRICATION IN A SINGLE SYNTHETIC STEP OF ELECTROCHEMICALLY ACTIVE LIMO2 (M = NI AND CO) THIN-FILM ELECTRODES USING SOFT SOLUTION PROCESSING AT 20-200 DEGREES-C

Well-crystallized and electrochemically active Li1-xNi1+xO2 and LiCoO2 thin-film electrodes for lithium rechargeable microbatteries can be f abricated in a single synthetic step using an economical, less energy consuming, and environmentally friendly ''Soft Solution Processing'' m ethod in a concentrated LiOH solution at fixed temperatures between 20 and 200 degrees C without any postsynthesis annealing. While the pure ly hydrothermal treatment of cobalt plates directly leads to the forma tion of LiCoO2 films, Ni(OH)(2) films on nickel plates are fabricated under the same hydrothermal conditions. By using the electrochemical-h ydrothermal approach under supplementary galvanostatic charge with the same hydrothermal conditions, Li1-xNi1+xO2 films can only be effectiv ely prepared in a single synthetic step from nickel plates. Such diffe rent activation methods required for the preparation of LiCoO2 and Li1 -xNi1+xO2 films respectively can be ascribed to the different metal ca tion valencies between dissolved nickel species (that contain divalent nickel) and dissolved cobalt species (that should possess trivalent c obalt).