Porous core-shell LiMn2O4 microellipsoids as high-performance cathode materials for Li-ion batteries

Porous LiMn2O4 microellipsoids with a solid-core@void@porous-shell configuration are synthesized by a facile self-template method. The structure and morphology of the microellipsoids are characterized with X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and Brunauer-Emmett-Teller (BET) techniques. The electrochemical properties are investigated by cyclic voltammetry, electrochemical impedance spectroscopy and charge-discharge testing methods. Porous core-shell microellipsoids exhibit excellent rate capability and cycling performance as a cathode material for Li-ion batteries. At a high rate of 10 C, LiMn2O4 microellipsoids maintain 70% of the discharge capacity obtained at 1 C rate. The capacity retains 90.1% after 400 cycles at a discharge rate of 5 C at room temperature. LiMn2O4 microellipsoids also show good cycling performance with the capacity retention of 77.1% after 200 cycles under 5 C rate at elevated temperature (55 °C). A high chemical diffusion coefficient of lithium ion in LiMn2O4 microellipsoids is determined by cyclic voltammetry method, suggesting the fast Li-ion intercalation kinetics and excellent high-rate performance. Porous LiMn2O4 microellipsoids could be a competitive cathode material for high-performance Li-ion batteries.