β-MnO2 sacrificial template synthesis of Li1.2Ni0.13Co0.13Mn0.54O2 for lithium ion battery cathodes

Abstract

Lithium-rich manganese-based oxide Li_1.2Ni_0.13Co_0.13Mn_0.54O₂ nanorods and polyhedrons have been successfully prepared using precursor β-MnO₂ nanorods as sacrificial templates at a calcination temperature of 750, 800, 850 or 900 °C. X-ray diffraction (XRD) and scanning electron microscope (SEM) measurements show that the elevated calcination temperatures help to improve the layered structure and average particle size of the target products. Rod-like Li_1.2Ni_0.13Co_0.13Mn_0.54O₂ can be obtained at low calcination temperatures (i.e., 750 and 800 °C), which becomes polyhedral at 850 or 900 °C. As lithium ion battery cathodes, the Li_1.2Ni_0.13Co_0.13Mn_0.54O₂ obtained at 850 °C shows the highest discharge capacity of 239.2 mA h g⁻¹ at 20 mA g⁻¹, and a stable discharge capacity of 92.8 mA h g⁻¹ at 1000 mA g⁻¹. The good electrochemical performances of the 850 °C sample should be attributed to the better crystal structure and/or the more appropriate particle size compared with those of other samples.