Effect of Mn Content on the Microstructure and Electrochemical Performance of LiNi[sub 0.75−x]Co[sub 0.25]Mn[sub x]O[sub 2] Cathode Materials

Newly developed cathode materials were successfully synthesized by mixing and via the solid-state reaction followed by heating to elevated temperatures. X-ray diffraction patterns showed that the samples calcined at exhibited a typical hexagonal structure without any other impurities present. The ratio of peak intensities of (003) to (104) decreased with the increasing Mn content. The scanning electron microscopy micrograph revealed uniform primary particle size, and the small primary particles agglomerated to form the secondary ones with size distribution in the range of . The X-ray photoelectron spectroscopy measurement indicated that the valence of Ni ions was a mixture of and . The amount of Mn substituted for Ni increased proportional to the ratio of in the samples was increased. Besides, for dynamic equilibrium , small amount was reduced to . After cycling, the cathode materials showed good electrochemical performance, with initial discharge capacity around at rate in the voltage range of . At a high rate of , 85% efficiency was still attainable in all samples.