Structure, morphology and electrochemical properties of Li[Li_0.2Co_0.4Mn_0.4]O₂ cathode material synthesized by a simple hydrothermal method

The nano-sized material Li[Li_0.2Co_0.4Mn_0.4]O₂ was synthesized by a simple hydrothermal method. X-ray diffraction results showed that the synthesized material had a hexagonal structure with additional peaks caused by monoclinic distortion. Scanning electron microscopy and transmission electron microscopy showed the homogeneous distribution of particles with 100-200 nm. X-ray photoelectron spectroscopy results indicated that the oxidation states of Co and Mn in Li[Li_0.2Co_0.4Mn_0.4]O₂ were present in trivalence and tetravalence, respectively. The charge-discharge curves, cycling performance and dQ/dV plots were analyzed in detail. The first charge/discharge profile behavior of Li[Li_0.2Co_0.4Mn_0.4]O₂ was also discussed. The initial charge and discharge respectively yielded the specific capacity of 199.3 mAh g^-1 and 174.2 mAh g^-1, with relatively high coulombic efficiency of 87.4% at the current density of 100 mA g^-1 in the voltage range of 2.0-4.6 V at 25 °C.