Nanocrystalline LiMn2O4 preparation and kinetics of thermal process of precursor

Abstract

Nanocrystalline LiMn2O4 was synthesized by calcining LiMn2(CO3)2.5·0.8H2O above 600 °C in air. The precursor and its calcined products were characterized by thermogravimetry and differential scanning calorimetry, X-ray powder diffraction, and scanning electron microscopy. The result showed that highly crystallization LiMn2O4 with cubic structure [space group Fd-3m(227)] was obtained when the precursor was calcined at 600 °C in air for 1.5 h. The thermal process of the precursor in air experienced three steps which involved, at first, the dehydration of 0.8 water molecules, then decomposition of MnCO3 into Mn2O3, at last, reaction of Mn2O3 and Li2CO3 into cubic LiMn2O4. Based on Starink equation, the values of the activation energies associated with the thermal process of LiMn2(CO3)2.5·0.8H2O were determined. Besides, most probable mechanism functions and thermodynamic functions (ΔS≠, ΔH≠, and ΔG≠) of thermal processes of LiMn2(CO3)2.5·0.8H2O were also determined.