Structure and electrochemical performance of Samarium substituted LiNi_1/3Mn_1/3Co_1/3O₂ cathode materials for rechargeable lithium-ion batteries

Large-scale energy storage required high energy density, high cyclic stabilities during high voltage operation and large specific capacity. In this record Li-rich cathode material LiNi_1/3Mn_1/3Co_1/3O₂ was doped with Sm is synthesized using citric acid as a chelating agent. Different amount of Sm was doped to investigate the effect of physical and electrochemical properties. The prepared samples were characterized by thermo gravimetric differential thermal analysis (TG-DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), cyclic voltammetry (CV), electrochemical impedance spectra (EIS) and galvanostatic charge–discharge techniques. The powder material was calcined at 800 °C for 10 h which exhibits a polyhedral structure. The electrochemical measurements of (LiNi_1/3Mn_1/3Co_1/3−xSm_x)O₂ cathode materials possess the best performance, especially at a high rate. The initial discharge capacity of 264.1 mA h⁻¹ at 0.1 C has reduced only 10.57% after the 100th cycle. Electrochemical impedance spectrum indicates that, LiNi_1/3Mn_1/3Co_1/3−xSm_xO₂ electrode has lower resistance during cycling. Such an improvement is associated with the doping of Sm enhancing the ability of Li diffusion in LiNi_1/3Mn_1/3Co_1/3−x Sm_xO₂ components. Results indicate that the structure of dopant samples have exhibited enhanced electrochemical performance with higher capacity and excellent cyclic capacity compared with the parent component.