The effects of Al2O3 coating on the performance of layered Li1.20Mn0.55Ni0.16Co0.09O2 materials for lithium-ion rechargeable battery

The 5 wt.% Al2O3-coated Li1.20Mn0.55Ni0.16Co0.09O2 was prepared by the mechanochemical reaction. The optimal condition for sample preparation was determined to be the rotation speed of 2000 rpm and the reaction time of 5 min by SEM, XRD, and XANES measurements. Surface analysis using XANES data demonstrated that all the samples were rather uniformly covered with nano-Al2O3 particles. The pristine and 5 wt.% Al2O3-coated samples after the stepwise pre-cycling treatment showed the discharge capacity of 243 and 216 mAh/g at 323 K, respectively. Although the Al2O3-coated sample showed less discharge capacity compared with the pristine sample, the Al2O3-coated sample showed better discharge capacity retention compared with the pristine sample after 35 cycles at 323 K. These results demonstrate that the mechanochemical Al2O3-coating process is an effective way of improving the cycle performance at high temperature.