Structural and electrical studies of LiMnVO4 cathode material for rechargeable lithium batteries

Abstract

The lithium manganese vanadate (LiMnVO 4 ) cathode material was synthesized by using sol-gel method. The thermal behavior of the material has been examined by thermogravimetric and differential thermal analysis. The structure of LiMnVO 4 compound was studied by the Rietveld refined X-ray diffraction technique. Raman spectra showed that the local environment including VO 4 tetrahedra and LiO 6 octahedra as vibrational local units. X-ray photoelectron spectroscopy studies of synthesized LiMnVO 4 powder indicate that the oxidation states of manganese and vanadate are +2 and +5, respectively. The ionic conductivity of the sample is found to be 2.7×10 −5 Scm −1 at 300°C. The temperature dependent conductivity was conformed from the Arrhenius relation and the activation energy is found to be 0.3 eV. Dielectric spectra showed the decrease in dielectric constant with increase in frequency. Dielectric loss spectra reveal that dc conduction contribution predominates in the compound.

Structural, Morphological and Optical and Electrical Properties of Ba0.4Cu0.6-xLaxTiO3 (x = 0.2, 0.4, 0.6) Nanoparticles

“…Higher impedance value at lower frequency region indicates the presence of space charge polarization. The Z' peak shift toward higher-frequency region with increase in temperature reveals the presence of frequency relaxation process [18][19]. It is observed from Figs.…”

“…As temperature increases, the magnitude of Z'' decreases, and the peak shifts toward higher-frequency region. The complex impedance data provides information about the relaxation process and gives frequency-dependent phenomenon associated with grain boundary regions and intrinsic properties of material in the system [18][19].…”

IMPEDANCE SPECTROSCOPY STUDIES OF NANO-CRYSTALLINE LiFePO4 CATHODE SYNTHESIZED BY HYDROTHERMAL METHOD

“…These plots allow the resistances related to grain interiors (bulk), grain boundaries and sample/electrode interfaces to be separated because each of them has different relaxation times, resulting in separate semicircles in the complex impedance plane. The relaxation frequency for the bulk is one or two orders of magnitude higher than the relaxation frequency for grain boundaries and the relaxation frequency resulting from the electrode process is much smaller than relaxation frequency of grain boundaries [10].…”

Impedance, dielectric and modulus analyses of compounds LiMnVO4and LiCuVO4

“…Very recently, a sol-gel synthesis of LiMnVO 4 has been suggested in Ref. 30, and an electrical study of the thus prepared samples has been carried out. This electrical study is however limited only in the temperature range from 200 to 300uC.…”