Structure/interface synergy stabilizes high-nickel cathodes for lithium-ion batteries

Abstract

Due to their high specific capacity, high-nickel layered oxides have been at the forefront of the development of high-energy-density lithium-ion batteries. However, high-nickel cathodes invariably suffer from structural and thermal instability, which severely hinders their large-scale application. Herein, we propose a synergistically stabilized LiNi_0.928Co_0.072O₂ cathode through Al structural doping and MoO₃ interfacial coating. In situ EIS, in situ XRD, and in situ DEMS measurements confirm that stronger Al–O bonds can inhibit crystal structure degradation, while MoO₃ coating effectively avoids the direct contact between the active materials and the electrolyte and suppresses the side reactions at the interface. Furthermore, the oxygen vacancy formation energy increases with the combined effects of the stable Al–O bond and the MoO₃ coating layer. The combined effects also suppress the generation of residual lithium, such as LiOH/Li₂CO₃, and improve the interface stability of the cathode. Therefore, the Al/MoO₃ synergistic cathode has no obvious gas evolution during the delithiation process and shows better high-temperature stability as there is no apparent voltage decay under a high temperature of 55 °C. The dual thermally stabilized strategies can suppress the structural degradation and stabilize the interface of the cathode, which provides new insights for the development of high specific energy and high safety cathode materials for lithium-ion batteries.