Structural and Morphological Studies of Two-Step Synthesized LiCoO₂ and Microwave Synthesized LiFePO₄ Particles

ABSTRACT

Crystalline dispersible LiCoO₂ nanoparticles were synthesized by a rapid two-step method. In the first step, Co₃O₄ nanoparticles were obtained by facile microwave assisted hydrothermal method. In the second step, the as-sy nthesiz ed Co ₃O₄ nanoparticles were transformed into LiCoO₂ nanoparticles through solid-state reaction method. Olivine LiFePO₄ with spindle like microstructure was prepared by rapid microwave assisted hydrothermal method within short time at 140°C. The synthesized samples were characterized by X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM ) and energy dispersive X-ray spectroscopy (EDX). The XRD reflection peaks revealed that the synthesized LiCoO₂ belongs to R-3m space group with hexagonal crystal structure. No impurity phase of Co₃O₄ was detected in LiCoO₂ after calcination at 750°C for 1 h. Powder XRD results also authenticated the formation of LiFePO₄ phase with orthorhombic crystal structure. FTIR analysis revealed the structural co-ordination of the prepared L iF ePO₄ particles. SEM analysis showed the formation of monodispersed LiCoO₂ nanoparticles with spherical particle morphology. For LiFePO₄, SEM analysis revealed the formation of porous spindle like microstructure, composed of densely packed secondary nanoflakes. Further, EDX spectra of the samples confirmed the presence of corresponding elements in the synthesized samples.

GRAPHICAL ABSTRACT

Keywords:

• Cathode material
• LiCoO₂
• LiFePO₄
• Microwave synthesis
• Structural properties
• Morphology