Study on improving the cycling stability of LiNi_0.92Co_0.04Mn_0.04O₂ cathode material by synergistic Al₂O₃/LiAlO₂

Lithium-ion batteries (LIBs) are one of the most common energy storage devices, and the high nickel LiNi_0.92Co_0.04Mn_0.04O₂ positive electrode has attracted much attention due to its high specific discharge capacity. However, the energy storage capacity of LIBs will be weakened with the cycle due to the chemical and structural changes of active substances on the surface of the positive electrode during the long cycle. Understanding and mitigating these degradation mechanisms is key to reducing capacity degradation and improving the cycle life of lithium-ion batteries. Coating is a common modification method, which can improve the stability of high nickel LiNi_0.92Co_0.04Mn_0.04O₂ positive electrode interface and reduce the surface degradation degree. However, the thickness and uniformity of the coating layer formed by conventional coating methods are difficult to regulate. In order to improve this problem, the co-modification effect of the Al₂O₃/LiAlO₂ thin film on LiNi_0.92Co_0.04Mn_0.04O₂ was reported in this paper. The formed double coating layer with uniform thickness enhanced the cycle performance and structural stability of the cathode material. The results showed that the Al₂O₃/LiAlO₂ double coating layer could effectively inhibit the irreversible phase transformation and improve the structural stability of the material. The modified material exhibited excellent cyclic stability with a discharge specific capacity of 141.2 mAh/g and a capacity retention of 76.1% at a voltage range of 2.75 to 4.40 V for 200 cycles. This work provides a new way to the modification for the interface of commercial cathode materials.