Nano-Crystalline Li_1.2Mn_0.6Ni_0.2O₂ Prepared via Amorphous Complex Precursor and Its Electrochemical Performances as...

An amorphous complex precursor with uniform Mn/Ni cation distribution is attempted for preparing a nano-structured layered Li-rich oxide (Li_1.2Mn_0.6Ni_0.2O₂)cathode material, using diethylenetriaminepentaacetic acid (DTPA) as a chelating agent. The materials are characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electrochemical tests. The crystal structure of Li-rich materials is found to be closely related to synthesis temperature. As-obtained nano materials sintered at 850 °C for 10 h show an average size of 200 nm with a single crystal phase and good crystallinity. At a current density of 20 mA·g^-1, the specific discharge capacity reaches 221 mAh·g^-1 for the first cycle and the capacity retention is 81% over 50 cycles. Even at a current density of 1000 mA·g^-1, the capacity is as high as 118 mAh·g^-1. The enhanced rate capability can be ascribed to the nano-sized morphology and good crystal structure.