Structure Evolution And Electrochemical Performance Of Al2o3-Coated Lini0.4co0.2mn0.4o2 During Charge-Discharge Cycling

Several lithium-ion batteries of 18650-type were assembled with pristine or Al2O3-coated LiNi0.4Co0.2Mn0.4O2(NCM) as cathode material and mesocarbon microbeads(MCMB) as anode material. The cycling performance of the batteries was examined under 25 degrees C at a 2C rate within a potential range of 2.75-4.20 V. The changes of the crystal structure, the lattice parameter, the mean crystallite size, and the mean micro-strain of pristine NCM and Al2O3-coated NCM during the charge-discharge cycling were determined by X-ray diffraction(XRD). The results indicate that the bulk structure of Al2O3-coated NCM is more stable than that of pristine NCM, which leads to the better cycling performance of Al2O3-coated NCM compared to that of pristine NCM.