Structural and electrochemical properties of LiNi0.3Co0.7O2 synthesized by different low-temperature techniques

Single phase LiNi1-yCoyO2 (y = 0.7) with fine particles were prepared by two different low-temperature methods, namely sol-gel and combustion techniques. It was found that bulk quantities of submicron-sized particles of layered LiNi0.3Co0.7O2 can be obtained at temperatures below 400 degrees C by these solution techniques. The methods involved the mixing of either acetates or nitrates of the metals, Ni and Co, with a chelating agent, carboxylic acid (sol-gel method) or a complexing agent, glycine (combustion method) in an aqueous medium. Both carboxylic acid and glycine acted as fuels, decomposed the homogeneous precipitate of metal complexes at low temperature, and yielded the free impurity LiNi0.3Co0.7O2 compound. The synthesized products were characterized by structural (XRD, SEM), spectroscopic (FTIR) and thermal (DTA-TG) analyses. The electrochemical performance of the synthesized products in rechargeable Lithium cells were evaluated using a non-aqueous organic electrolyte mixture of 1M LiPF6 in EC + DMC. The electrochemical behavior of synthesized LiNi0.7Co0.3O2 is discussed in relation with its synthesis procedures. (C) 1999 Elsevier Science Ltd. All rights reserved.