Improved Electrochemical Properties of Al3+-doped 0.5Li2MnO3-0.5LiCo1/3Ni1/3Mn1/3O2 Cathode for Lithium Ion Batteries

The lithium-rich cathode materials Li[Li0.2Co0.13Ni0.13Mn0.51Al0.03]O-2 doped with 3% Al3+ were synthesized by a polymer-pyrolysis method. The structure and morphology of the as-prepared material were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM). The structural analyses exhibit that the Al3+-doped sample maintains the layered structure of the Li-rich oxide material and no impurity is detected in XRD patterns. The charge-discharge tests show that the Al3+-doped sample has a high charge/discharge capacity of 349.1/303.8 mAh/g (initial coulombic efficiency of 87%) at current density of 30 mA/g. Additionally, Al3+-doped sample also exhibits excellent cyclability with 91.7% capacity retention over 100 cycles. The results demonstrate that Al3+ doping is favorable to maintain the structural stability of the layered structure during the electrochemical lithium insertion/extraction, so as to provide a promising route to develop cathode materials with high capacity and stability.