Influence of Co-substitution on Structure and Electrochemical Performances of Li-rich Spinel LiMn2O4

In this paper, the non-stoichiometric spinel LiMn2O4 was synthesized by solid-state reaction using Mn2O3 as Mn source, and the influence of Co-substitution on structure and electrochemical performances of spinel LiMn2O4 was researched. The structure was characterized by X-ray diffraction (XRD) and infrared spectroscopy (IR), morphology was examined by scanning electron microscopy (SEM), and chemical composition of samples were analyzed by the energy-dispersive X-ray spectrum (EDX), while the doping dosage of Co element was measured by inductively coupled plasma (ICP). The results show that the Co-substituted Li1.03Mn2O4 samples display a single phase of cubic spinel structure, and have enhanced particle size uniformity and surface smoothness. The electrochemical performance tests show that the rate capability and cycling performances of Co-substituted samples are significantly improved compared with that of pristine Li1.03Mn2O4. The sample (Li1.03Mn0.85Co0.15O4) with 15 mol% of Co-substitution has discharge capacity of 106mAh . g(-1) at 2C and shows an improved average capacity retention of 97.2% compared with that of the Li1.03Mn2O4 which shows 87.7% capacity retention after 50 cycles at 1C rate.