Study of Alternative Current Conduction Mechanisms on the α-LiFeO2-Based Cathode Materials

Abstract

An improved solid-state synthesis method was used to create LiFeO₂ layered oxides. The produced material adopts a cubic system (Fm-3m space group) with a refined cell parameter of a = 4.156(9) Å, as indicated by Rietveld refinement of the crystal structure. A morphological investigation revealed that the sample is composed of small primary particles with sizes ranging from 0.20 to 0.75 μm. IR spectroscopy vibrational analysis revealed the presence of FeO₆ and LiO₆ groups. The compound's semiconductor nature was confirmed when the band gap energy was generated and discovered to be 2 eV. There is a tighter dispersion of localized states within the band gap, as indicated by the obtained Urbach energy (0.39 eV), which presents just 20% from the band gap energy. The material's dielectric characteristics were assessed between 0.1 and 107 Hz in frequency and between 333 K and 523 K in temperature. The presence of both space charge and dipolar polarization is suggested by the real component of the dielectric permittivity, which indicates a high dielectric constant (between 100 and 350) at low frequency. The circuits are made up of constant phase elements (CPE) and bulk resistance R coupled in parallel. Jonscher's law was applied to interpret the frequency-dependent conductivity. The outcomes of the charge transport investigation on LiFeO₂ imply that the layered oxide material possessed a large polaron tunneling (OLPT) paradigm with activation energy E_a of 0.26 eV. Comparing the polaron R_ω (2 < R_ω < 5 Å) optimal hopping length to the Li–O interatomic gap (2.077(9) Å), it is larger. We identified and examined a correlation between the ionic conductivity and the crystal structure.