Synthesis and characterization of spinel Li 1+ xCo yMn 2− yO 4 by oxalate precipitation

Abstract

Synthesis and high temperature phase stability of spinel Li 1+ x Co y Mn 2− y O 4 (0≤ x≤0.2, y=0, 1/9, 1/6) have been studied. The spinel powders were prepared by oxalate precipitation method. Single phase spinel was synthesized at the temperature lower than 600 °C. As a result of the thermal gravimetric-differential thermal analysis (TG-DTA) of prepared powders, phase transitions at temperatures T 1, T 2 and T 2′ were found. An X-ray diffraction (XRD) study on powders quenched from above the transition temperatures showed high temperature phases of irreversible and reversible. The reversible phases could be only transformed back into the spinel phase when they were cooled slowly. The effects of both the Li excess and Co doping on the spinel lattice constant, phase stability, transition temperatures and capacity on cycling were investigated.