Electrical and dielectric study of Na 2/3 Mn 2/3 Fe 1/3 O 2 as a cathode active material for sodium-ion batteries

• Published in: New journal of chemistry 2024-07, Vol.48 (28), p.12817-12827
• Main Authors: Missaoui, Faouzi, Krimi, Moufida, Mahmoud, Abdelfattah, Boschini, Frédéric, Ben Rhaiem, Abdallah
• Format: Article
• Language: English
• ISSN: 1144-0546; 1369-9261
• DOI: 10.1039/D4NJ01969E

Na 2/3 Mn 2/3 Fe 1/3 O 2 layered oxides were synthesized using an enhanced solid-state synthesis method. Analysis via XRD confirmed the high purity of the prepared samples. Rietveld refinement of the crystal structure revealed that the synthesized materials adopt a rhombohedral system with the P 63/ mmc space group and P2 structure type. Calorimetric study confirms the presence of two-phase transitions at 393 K and 433 K. Vibrational investigation conducted using IR spectroscopy demonstrated the presence of an MO 6 group. The dielectric properties of the material were evaluated over a frequency range of 0.1–10 7 Hz across temperatures ranging from 313 K to 453 K. The study of the real part of the dielectric permittivity using impedance spectroscopy suggested a high dielectric constant at low frequency and indicated the existence of both space charge and dipolar polarizations. The dielectric losses were analyzed according to the Giuntini law to extract the relaxation process. As a result, the module revealed two relaxations attributed to grain boundaries and grain relaxations. The frequency-dependent conductivity was interpreted following Jonscher's law. The variation of the power law exponent with temperature, corresponding to the grains s 1 and s 2 , suggests that the conduction behavior of the P2-Na 2/3 Mn 2/3 Fe 1/3 O 2 compound can be ascribed to the NSPT and CBH models.