Significantly improving cycling performance of cathodes in lithium ion batteries: The effect of Al2O3 and LiAlO2 coatings on LiNi0.6Co0.2Mn0.2O2

LiNi 0.6 Co 0.2 Mn 0.2 O 2 (NCM) is a highly potential cathode material for lithium-ion batteries (LIBs). However, its poor rate capability and cycling performance at high cutoff voltages have seriously hindered further commercialization. In this study, we successfully design an ultra-thin lithium aluminum oxide (LiAlO 2 ) coating on NCM for LIBs. Compared to Al 2 O 3 , the utilization of lithium-ion conducting LiAlO 2 significantly improves the NCM performance at high cutoff voltages of 4.5/4.7   V. The study reveals that the LiAlO 2 -coated NCM can maintain a reversible capacity of more than 149   mA   h   g −1 after 350 cycles with 0.078% decay per cycle. Furthermore, LiAlO 2 -coated NCM exhibits higher rate capacities [206.8   mA   h   g −1 at 0.2   C (50   mA   g −1 ) and 142   mA   h   g −1 at 3   C] than the Al 2 O 3 -coated NCM (196.9   mA   h   g −1 at 0.2   C and 131.9   mA   h   g −1 at 3   C). Our study demonstrates that the ultra-thin LiAlO 2 coating is superior to Al 2 O 3 and significantly improves the capacity retention and rate capability of NCM for LIBs.