High performance Li1·2(Mn0·54Co0·13Ni0·13)O2 with AlF3/carbon hybrid shell for lithium ion batteries.

A kind of core shell cathode material, (LMSAC) was prepared by coating AlF3 and carbon hybrid layer on the surface of lithium rich manganese based solid solution (LMSS) through a sol-gel process. It was characterised by X-ray diffraction (XRD) patterns, scanning electron microscope (SEM) and transmission electron microscope (TEM). Its electrochemical properties were evaluated by electrochemical impedance spectra and galvanostatic charge-discharge measurements. Owing to the AlF3/C shell, the LMSAC could deliver the initial capacities of 278, 260, 246, 230 and 210 mAh g−1 at the rates of 0·1, 0·2, 0·5, 1 and 2C in the potential range of 2-4·8 V (versus Li+/Li) respectively, exhibiting an excellent rate capability. The corresponding coulombic efficiencies are 90, 89, 87, 88 and 85% in the first cycle. After cycled at the 0·1C and 1C rates for 50 times, the LMSAC remains 97 and 96% of the initial capacities respectively, displaying an enhanced cycling performance. The results suggest that surface coating of AlF3/C hybrid layer could be a promising method to improve the electrochemical properties of the LMSS cathode materials. [ABSTRACT FROM AUTHOR]