Effects of doping Al on the structure and electrochemical performances of Li[Li0.2Mn0.54Ni0.13Co0.13]O-2 cathode materials

The Li-rich cathode material Li[Li0.2Mn0.54Ni0.13Co0.13]O-2 had been successfully synthesized by a carbonate coprecipitation method. The effects of substituting traces of Al element for different transitional metal elements on the crystal structure and surface morphology had been investigated by X-ray diffraction (XRD) and field emission scanning electron microscopy. The results revealed that all the materials showed similar XRD patterns and surface morphology. It was demonstrated that LNCMAl1 exhibited the superior electrochemical performance. The discharge capacity was 265.2 mAh g(-1) at 0.1 C and still maintained a discharge capacity of 135.6 mAh g(-1) at 5.0 C. The capacity retention could still be 58.2 and 66.8% after 50 cycles at 1.0 and 2.0 C, respectively. Electrochemical impedance spectra results proved that the remarkably improved rate capability and cycling performance could be ascribed to the low charge transfer resistance and enhanced reaction kinetics.