Enhancement of the electrochemical performance of LiNi0.5Mn1.5O4 cathode materials for Li-ion battery by Mo-F co-doping

The pristine LiNi0.5Mn1.5O4 (LNMO) and Mo-F co-doped LiNi0.5Mn1.5O4 spinel materials were prepared via a rheological phase method. The four samples were analyzed by X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), transmission electron microscope (TEM), and X-ray photoelectron spectroscopy (XPS). Compared with the pristine LNMO sample, Mo-F co-doped LNMO materials could increase the lattice parameters, reduce particle sizes, and significantly improve the electrochemical performances of LNMO. The doped material exhibited optimum electrochemical properties when the Mo and F doping amounts were 1% and 3%, respectively, denoted as Mo/F-2. The discharge capacity retention of Mo/F-2 is 95.6%, which is higher than the pristine sample (87.7%) after 100 cycles at 1C and room temperature. Furthermore, the discharge-specific capacity of the Mo/F-2 sample reaches 113.4 mAh g(-1) at 5C, while the pristine sample reaches only 61.9 mAh g(-1). After CV and EIS analysis, it was found that the Mo-F co-doped LNMO materials had better Li+ diffusion kinetics than the pristine LNMO sample. Thus, Mo-F co-doping is considered an effective modification method for LNMO cathode material.