Investigation on performance of Li(Ni0.5Co0.2Mn0.3)1−xTixO2 cathode materials for lithium-ion battery

Abstract

In order to investigate the influences of modification on industrial-grade cathode materials, layered Ti-doped Li(Ni0.5Co0.2Mn0.3)1−xTixO2 cathode materials have been synthesized via a simple solid state method using industrial raw materials in bulk scale (>10kg) in this work. X-ray diffraction (XRD), Rietveld refinement, scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) mapping, particle size distribution and electrochemical tests including cyclic voltammetry (CV) and electrical impedance spectroscopy (EIS) have been used to characterize electrochemical performance of industrial-grade cathode materials. The results of XRD, SEM and EDS mapping characterization indicate that all the modified cathode materials with their Ni, Co and Mn components doped by titanium keep a typical α-NaFeO2 layered structure with R-3m space group and titanium atoms are uniformly distributed in all series of Ti-doped materials as prepared. Electrochemical characterization confirms that the material of 0.2% Ti doping has the best cycling performance and the least capacity loss because of its best cation ordering figured by Rietveld refinement of XRD. The initial discharge capacity of 0.2% Ti doping material achieves 185.0mAh/g at 1C between 2.8 and 4.6V. Additionally, the capacity retention maintains at 93.4% after 200 charge–discharge cycles.