High structural stability and Li-conduction of LiNi 0.8 Co 0.1 Mn 0.1 O 2 cathode co-coated by Al 2 O 3 and LiNbO 3 for high performance lithium-ion battery

Lithium-ion batteries (LIBs) hold promise for revolutionizing the next generation of battery systems due to the utilization of high specific capacity LiNi x Co y Mn 1− x − y O 2 (NCM) cathode materials. However, despite extensive research efforts towards further commercialization of NCM across various fields, challenges persist, particularly related to structural instability and side reactions with liquid electrolytes, resulting in inevitable capacity fade during cycling. In this study, we present a facile surface co-coating method for polycrystalline LiNi 0.8 Co 0.1 Mn 0.1 O 2 (NCM811), employing stable, cost-effective Al 2 O 3 and lithium-ion conductive LiNbO 3. While Al 2 O 3 provides a specific enhancement to create a durable coating layer, LiNbO 3 is well known as the high ion-conductive coating layer. Owing to the synergistic effects of the co-coating layer with an optimal coating amount, Al 2 O 3 –LiNbO 3 co-coated NCM exhibited excellent electrochemical properties. At a loading level of 3 g cm −3 , it achieves a discharge capacity of 187.35 mA h g −1 at 0.2C and 76.53 mA h g −1 at 5C. Furthermore, the retention rate of Al 2 O 3 –LiNbO 3 co-coated NCM reaches 92.51% at 0.5C after 100 cycles, compared to only 87.70% of the uncoated NCM. Our study demonstrates the significant improvement in the electrochemical performance of NCM facilitated by the Al 2 O 3 –LiNbO 3 co-coating, surpassing single-coating strategies.