Thermoanalytical study of synthesis of mixed lithium cobalt oxides

The synthesis of LiCoO2 from different precursor mixtures, such as Li2CO3-Co3O4, Li(CH3COO).2H2O-Co3O4, Li2CO3-2CoCO(3) . 3Co(OH)(2) and Li(CH3COO). 2H(2)O-Co (CH3COO)(2) . 4H(2)O in air has been studied by means of TG, DTG and DTA techniques. The thermal events have been characterized by X-ray diffraction and chemical analysis. It is suggested that the synthesis proceeds through reaction between lithium carbonate and cobalt oxide intermediates. A lower synthesis temperature has been observed in the case of acetate precursors. The effect of the precursor on the electrical properties of the samples has been also studied. Measurements of electrical conductivity in the temperature range 600 to 900 degrees C in air show typical semiconductive behaviour for all the samples of LiCoO2. The Arrhenius plots show two linear regions with a temperature break due to phase transition near 850 degrees C. The two values of activation energies in the temperature ranges 600-820 and 850-900 degrees C have been found to be similar for all the samples, suggesting that the conduction behaviour should not be influenced by the nature of the precursor.