Abstract:
Mg substituted lithium nickel phosphates, LiNi0.925Mg0.075PO4 and LiNi0.9Mg0.1PO4 cathode
materials are synthesized by three steps solid state reaction method. These materials are
characterized by thermogravimetric analysis (TGA), differential thermogravimetric analysis
(DTA), x-ray powder diffraction (XRD), energy dispersive spectroscopy (EDS), Fourier
transform infrared (FT-IR) spectroscopy and complex impedance spectroscopy (CIS)
techniques. From TGA/DTA study, compound formation temperatures as well as the weight
loss regions are identified. XRD studies of the prepared samples confirm the formation
of good crystallization and well-defined diffraction peaks without impurities. The single-
phase formations of both samples are also confirmed by EDS analysis. From FT-IR study,
different peaks are observed at different wavelength regions, which are responsible for the
formation of LiNi0.925Mg0.075PO4 and LiNi0.9Mg0.1PO4 compounds. From the impedance
analysis, it is found that the dielectric constant decreases sharply at low frequency as
compared to that at high frequency and become almost constant on further increasing the
frequency for both samples. The dc conductivity values of LiNi0.925Mg0.075PO4 and
LiNi0.9Mg0.1PO4 are 3.8 x 10-9
Scm-1
and 3.94 x 10-9
Scm-1
, respectively. The obtained
conductivity results are found in the range of the electrical conductivity of semiconductor
(10-7
to 103
S/cm), indicating the semiconductor behavior of the samples.
