Al2O3 Surface Modification of NCM (Lithium Nickel Cobalt Mangenese Oxide) Cathode Materials via Sol-Gel Method

摘要

Long life and high energy density is still a major requirement for lithium ion batteries. New generation NCM cathodes provides high energy density but they are prone to degradation and that causes capacity losses. In the scope of this work, lithium rich NCM (Li[1.2]Ni[0.2]Co[0.08]Mn[0.52]O[2]) powder is produced via sol-gel method at 850°C heat treatment temperature. Afterwards, the surface of the NCM cathode is modified with 0.5 wt.% Al[2]O[3] via sol-gel method to improve electrochemical performance by preventing the challenges of Li-rich NCM cathode materials. Initial discharge capacities of pristine and modified samples are found to be 228.7 mAh/g and 235.2 mAh/g, respectively. Discharge capacity retentions are calculated as %68.9 and %87.9 after 50 cycle. Al[2]O[3] coating layer could act as a protective barrier which prevents the reactions between the cathode and electrolyte. Also, it could increase the structural stability of the cathode. Modified sample has found to have higher resistance than that of a pristine sample to increasing C-rates. After 50 cycle, SEM results show cracks in the pristine sample but no crack is observed at the modified one.