Preparation and electrochemical characterization of Li(Li0.17Ni0.2Co0.05Mn0.58)O2 coated with LiAlO2

Li-rich layered oxides Li(Li0.17Ni0.2Co0.05Mn0.58)O2 (LNCMO) and LiAlO2-coated samples were prepared by sol–gel method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The LiAlO2-coated sample shows good electrochemical performance compared with that of the pristine sample such as initial coulombic efficiency, cyclic performance, and rate capability. The LiAlO2-coated sample can deliver high initial discharge capacities of 268.2 and 191.9 mAh g−1 at 0.1 and 1 C rates with a capacity retention rate of 91.7 and 91.3 % after about 70 and 140 cycles, respectively. Meanwhile, it shows outstanding high-rate capability cyclability with less than 5 % capacity fade after 70 cycles at 5 C rate. The electrochemical impedance spectra (EIS) data indicate that the LiAlO2 coating can remarkably suppress the increase of the charge transfer resistance and restrain the structure change of LNCMO during the cycles which should make a great contribution to the high-rate capability of LiAlO2-coated LNCMO material.