Boron-doped Li1.2Mn0.6Ni0.2O2 as a cathode active material for lithium ion battery

Lithium-rich manganese-based layered oxide material, Li1.2Mn0.6Ni0.2O2, was successfully synthesized via a solid-state method, and its structural and electrochemical properties were compared with the boron-doped Li1.2Mn0.6-x/2Ni0.2-x/2Bx2O2 (x = 0, 0.02 and 0.04) cathode materials. The structure and morphology of the cathode samples have been investigated by X-ray powder diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The electrochemical properties of cathode materials have been characterized systematically with different electrochemical techniques. According to XRD and SEM results crystallite size of materials increase with increasing boron content. Boron doping exhibits remarkable improvement in capacity, cyclability and rate capability compared to bare Li1.2Mn0.6Ni0.2O2. The initial charge and discharge capacities at 0.1C rate were observed at 318 and 253 mAh g− 1 for Li1.2Mn0.6Ni0.2O2, 318 and 239 mAh g− 1 boron-doped materials, respectively. In addition, the boron-doped cathode exhibits a long-term cycling stability with the capacity fade of only 12% after 275 cycles at 1C current discharge rate. However, the addition of more boron does not have an extra electrochemical performance.