The effect of Co3O4 & LiCoO2 cladding layer on the high rate and storage property of high nickel material LiNi0.8Co0.15Al0.05O2 by simple one-step wet coating method

Co3O4 & LiCoO2 complex cladding layer with nutty-cake structure effectively improves high rate and storage properties of high nickel material LiNi0.8Co0.15Al0.05O2 (NCA), using a simple one-step wet-coating process, and the degradation of NCA is successfully restrained. The structure and morphology of samples are demonstrated by X-ray diffraction (XRD), scanning electron microscope (SEM), and field-emission high resolution transmission electron microscope (FEHRTEM). The elemental composition and distribution are determinate by energy dispersive spectrometer (EDS). In comparison with pristine NCA, 0.25 wt.% Co3O4-modified NCA has a better electrochemical performance with more capacity of approximate 30 mAh g−1 at 1C after 150 cycles. At 5C and 10C, it also exhibits better capacity retentions and higher capacities. After exposed to the air for 100 days, 0.25 wt. % Co3O4-modified NCA still shows better electrochemical performance than pristine NCA stored at the same condition. The improved comprehensive performance of Co3O4 & LiCoO2 coated NCA is related with the facile coating method in which Co3O4 is formed and the lithium impurity on NCA surface is consumed to produce LiCoO2 concurrently during calcining process. The reaction mechanism of Co3O4 & LiCoO2 composite layer is analyzed using the cyclic voltammetry (CV) and the electrochemical impedance spectroscopy (EIS).