Ceramics-Silikáty 53 (4) 260-267 (2009)

SYNTHESIS AND CHARACTERIZATION OF CITRIC ACID ASSISTED CR DOPED LITHIUM MANGANESE OXIDE SPINEL

G. Singh, A. Panwar, A. Sil, S. Ghosh

The powders in the system LiCr_xMn_2-xO₄ (0.0≤x≤0.5) were synthesized by sol-gel method using citric acid as a chelating agent. The powders were characterized by X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), Differential scanning calorimetry (DSC), Impedance spectroscopy (IS) and Electrochemical analysis. Change in particle morphology from truncated octahedral (tetradecahedra) to perfect octahedron for the higher doping concentration of Cr has been reported. Decrease in particle size has been observed with the increase in Cr content. The stability in the crystalline structure of LiMn₂O₄ cubic spinel over the temperature range of battery operation was achieved by chromium doping. The electrical conductivity at room temperature of the powdered samples in various compositions studied is of ~10-5 S/cm. Electrochemical analyses of the materials in all the compositions were carried out in the voltage range of 4.3 V to 3.0 V. The cubic to cubic phase transition in LiMn₂O₄ which occurs at around 4.15 V can be suppressed by Cr doping. The discharge capacity of the compound is maximum of ~130 mAh/g for the composition x = 0.0. The capacity decreases with increase in doping concentration and becomes minimum of ~80 mAh/g at x = 0.5.

Keywords: Sol-gel, Spinel structure, X-ray diffraction, Differential scanning calorimetry, Discharge capacity