Layered LiNi0.5Co0.5O2 cathode materials grown by soft-chemistry via various solution methods

The lithiated nickel-cobalt oxide LiNi0.5Co0.5O2 used as cathode material w as grown at low-temperature using different aqueous solution methods. The w et chemistry involved the mixture of metal salts (acetates or nitrates) wit h various carboxylic acid-based aqueous solutions. Physicochemical and elec trochemical properties of LiN0.5Co0.5O2 products calcined at 400-600 degree s C were extensively investigated. The four methods used involved complexin g agents such as either citric, oxalic, aminoacetic (glycine), or succinic acid in aqueous medium which functioned as a fuel, decomposed the metal com plexes at low temperature, and yielded the free impurity LiNi0.5Co0.5O2 com pounds. Thermal (TG-DTA) analyses and XRD data show that powders grown with a layered structure (R (3) over bar m space group) have been obtained at t emperatures below 400 degrees C by the acidification reaction of the aqueou s solutions. The local structure of synthesized products was characterized by Fourier transform infrared (FTIR) spectroscopy. The electrochemical prop erties of the synthesized products were evaluated in rechargeable Li cells using a non-aqueous organic electrolyte (1 M LiClO4 in propylene carbonate, PC). The LiNi0.5Co0.5O2 positive electrodes fired at 600 degrees C exhibit ed good cycling behavior. (C) 2000 Elsevier Science S.A. All rights reserve d.