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

Abstract

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.