Abstract

• The main aim of the research work is to study the preparation and characterization of LiNi1-xCoxO2 (0.2 ≤ x ≤ 0.5) nanocrystalline powder. LiNi1-xCoxO2 (0.2 ≤ x ≤ 0.5) nanocrystalline powders for lithium ion batteries were prepared by a modified sol–gel method using lithium nitrate (LiNO3), cobalt (II) nitrate (Co(NO3)2.6H2O), nickel(II) nitrate (Ni(NO3)2.6H2O) as starting materials, de-ionized water as solvent, citric acid (C6H8O7.H2O) as chelating agents and carboxy methyl cellulose as dispersant agent. The prepared LiNi1-xCoxO2 (0.2≤ x ≤ 0.5) nanocrystalline powder was characterized by TG- DTA, XRD, FT IR and SEM analyses.TG-DTA analysis of the synthesized LiNi1-xCoxO2 (0.2 ≤ x ≤ 0.5) nanocrystalline powder was carried out to determine the appropriate calcination temperatures. The prepared LiNi0.8Co0.2O2 powders were calcined at 600, 700, 800, 900 and 1000 C. The resulting calcined powders were characterized by XRD technique. The lattice parameters and the average crystalline size of the samples calcined at different temperatures were calculated using Debye Scherrer equation. It was observed that the crystallite size increases with increasing calcination temperature which may be due to the growth of particle size but the sample calcined at 800 C was selected as optimum temperature because the sample (LiNi0.8Co0.2O2) has high crystallinity and small crystallite size at this temperature. From XRD spectrum, the observed value of average crystallite size of LiNi0.8Co0.2O2 are 29.58 nm, 32.24 nm, 17.22 nm, 29.25nm and 47.62 nm at different temperatures. Therefore, the other three compounds such as LiNi0.7Co0.3O2, LiNi0.6Co0.4O2 and LiNi0.5Co0.5O2 were also prepared by using the same methods. The prepared (LiNi0.7Co0.3O2, LiNi0.6Co0.4O2 and LiNi0.5Co0.5O2) nanopowders calcined at 800C were characterized by XRD. From XRD spectrum, the average crystalline size of prepared three compounds are 69.94 nm, 41.76 nm, and 43.43 nm at 800 C. From FT IR analysis, it was only found stretching vibration of metal- oxygen chemical bonds. Surface feature study of the prepared nanocrystalline powders were observed from SEM. It was observed that agglomeration increase with high porosity and increasing Co doping levels.