High structural stability and Li-conduction of LiNi0.8Co0.1Mn0.1O2 cathode co-coated by Al2O3 and LiNbO3 for high performance lithium-ion battery

Abstract

Lithium-ion batteries (LIBs) hold promise for revolutionizing the next generation of battery systems due to the utilization of high specific capacity LiNi_xCo_yMn_1−x−yO₂ (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_0.8Co_0.1Mn_0.1O₂ (NCM811), employing stable, cost-effective Al₂O₃ and lithium-ion conductive LiNbO_3. While Al₂O₃ provides a specific enhancement to create a durable coating layer, LiNbO₃ 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, Al₂O₃–LiNbO₃ 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 Al₂O₃–LiNbO₃ 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 Al₂O₃–LiNbO₃ co-coating, surpassing single-coating strategies.