Impedance studies on the 5-V cathode material, LiCoPO 4

Abstract

Olivine-structured LiCoPO 4 is synthesized by a Pechini-type polymer precursor method. The structure and the morphology of the compounds are studied by the Rietveld-refined X-ray diffraction, scanning electron microscopy, Brunauer, Emmett, and Teller surface area technique, infrared spectroscopy, and Raman spectroscopy techniques, respectively. The ionic conductivity (σ ionic), dielectric, and electric modulus properties of LiCoPO 4 are investigated on sintered pellets by impedance spectroscopy in the temperature range, 27-50 °C. The σ (ionic) values at 27 and 50 °C are 8.8×10 -8 and 49×10 -8 S cm -1, respectively with an energy of activation (E a)00.43 eV. The electric modulus studies suggest the presence of non-Debye type of relaxation. Preliminary charge-discharge cycling data are presented.