الفهرس 
Characterization techniquesOnly 14 pages are availabe for public view
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Abstract
Lithium-ion batteries (LIBs) are regarded as reliable energy
storage technology for portable electronic technologies. The
disordered rocksalt Li-excess cathode materials are considered
promising materials for their significant properties. Despite most
studies are directed to the electrochemistry of Li-ion batteries
electrode materials, adequately few fundamental studies were
presented.
The thesis contains four chapters: chapter one, a survey of Li-
ion batteries with a review of the literature about its components,
electrolytes, anode, and cathode materials were presented. In
addition, the disordered rocksalt Li-excess (DRX) transition metal
(TM) oxide cathode materials were discussed. The fundamental and
theoretical background of optical, magnetic, thermodynamic, and
dielectric properties were presented. Chapter two presents the
experimental techniques of the synthesis and characterization
procedures of Li1.3Nb0.3Mn0.4O2 (LNMO) and Li1.3Nb0.3Fe0.4O2
(LNFO) in detail.
Chapter three presents the results of fundamental properties
investigation for the synthesized LNMO and LNFO cathode
materials and a discussion of these output results. Chapter four
presents the outcome results.
Since the electrochemical properties of the disordered rocksalt
Li-excess (DRX) Li1.3Nb0.3Me0.4O2 (Me = Mn, Fe), LNMO, and
LNFO only published, this work throw light on the fundamental
properties such as structural, optical, magnetic, thermodynamic, and
dielectric properties. Both LNMO and LNFO were prepared by
using the molten-salt method. The characterization of the as-
VIII
prepared samples was performed by different techniques: Powder
X-ray Diffraction (XRD), Field-Emission Scanning Electron
Microscope (FE-SEM), and Fourier Transform Infrared (FTIR)
spectroscopy.
The transient absorption spectroscopy (TAS) used the ultra-
fast laser to study the dynamics of charge carriers and electron-
phonon coupling in LNMO and LNFO systems. Magnetic DC and
AC susceptibility as well as the magnetization as a function of the
applied magnetic field revealed the magnetic ordering at low
temperatures that LNMO and LNFO have an antiferromagnetic
(AFM) transition at Néel temperatures (TN) of 6.5 K and 4.94 K,
respectively, with the coexistence of other canted AFM or weak
ferromagnetic (FM) phases as observed from the hysteresis loop.
The specific heat measurements at the different applied magnetic
fields are consistent with the observed magnetic behavior at low
temperatures. The thermal stability of LNMO and LNFO is
examined by thermogravimetry analysis (TGA) and differential
scanning calorimetry (DSC).
The dielectric properties of LNMO and LNFO show high
permittivity with losses in the low-frequency region. Furthermore,
the electrical modulus, as well as the AC conductivity as a function
of the frequency and temperature, were presented.