Molybdenum-doped lithium-rich layered-structured cathode material Li_1.2Ni_0.2Mn_0.6O₂ with high specific capacity and improved rate performance

Fine powders of Li_1.2Ni_0.2Mn_0.6−xMo_xO₂ (x = 0, 0.002, 0.005, 0.01, 0.05) are prepared by a thermopolymerization method. X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and electrochemical measurements are carried out to characterize these samples. The maximum Mo-doping level to obtain a pure layered phase is 0.005. The Mo-doped samples show a great improvement in rate performance and cycling stability. For the optimal composition Li_1.2Ni_0.2Mn_0.59Mo_0.01O₂, it exhibits a discharge capacity of 245 and 110 mA h g⁻¹ at 0.1 C and 5 C, respectively. It retains a capacity of 229 mA h g⁻¹ at 0.1 C after 204 cycles with a capacity retention of 93.2%. This study suggests that the partial substitution of Mn⁴⁺ with Mo⁶⁺ can improve both the rate capability and cycle performance of this high-capacity cathode material