Investigations on conductivity of nitrogen-doped rGO/Li2FeSiO4 cathode material prepared by microwave-assisted method for lithium-ion batteries

Document Type : Research Article

Authors

1 Department of Materials and Metallurgical Engineering, Amirkabir University of Technology, Tehran, Iran

2 Research Institute of Petroleum Industry (RIPI), Tehran, Iran

3 Faculty of Basic Science, Tarbiat Modares University, Tehran, Iran

Abstract

Li2FeSi04 (LFS) is a promising cathode active material for lithium-ion batteries due to its significant theoretical capacity (332 mAhg-1). Nevertheless, its practical electrochemical performance faces significant hurdles due to low electron conductivity. In the research, a simple solid-state technique was used to synthesize the high-purity cathode material LFS. Additionally, nitrogen-doped reduced graphene oxide nanosheets (N-rGO) were fabricated using a household microwave-assisted process and then selectively deposited to coat the active cathode material to increase conductivity and significantly improve electrocatalysis. The properties of the as-prepared N-rGO nanosheets and LFS/N-rGO nanocomposites are studied using X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), RAMAN spectrometry and Fourier transform infrared spectroscopy techniques (FTIR). The study investigated the influence of different amounts of N-rGO coatings on the electrical conductivity of the LFS by comparing their band gap energy value. Accordingly, lower band gap, indicating higher and better electronic conductivity in the cathode of lithium-ion batteries. Therefore, diffusion reflectance spectroscopy (DRS) and electrochemical impedance spectroscopy (EIS) were used to determine the band gap size and conductivity. Studies show that coating LFS particles with only 5 wt% N-rGO reduced the bandgap energy value by about 0.78 eV and increased the electrical conductivity by 54.31%. It is concluded that LFS/5N-rGO can be a promising candidate as a high-performance cathode material for lithium-ion batteries.

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AUT Journal of Mechanical Engineering
Volume 9, Issue 2
2025
Pages 167-178

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