Bifunctional Surface Coating of LiAlO<sub>2</sub>/Si<sub>1–<i>x</i></sub>Al<sub><i>x</i></sub>O<sub>2</sub> Hybrid Layer on Ni-Rich Cathode Materials for High Performance Lithium-Ion Batteries
Hongqiang Wang, Youqi Chu, Qichang Pan, Chunlei Tan, Ying Shi, Yan Li, Sijiang Hu, Fenghua Zheng, Youguo Huang, Qingyu Li
Abstract
As a candidate material for high energy density cathode, nickel-rich layered oxide cathode material LiNi0.6Co0.2Mn0.2O2 has become the current research hotspot for lithium-ion batteries. However, the instability of the surface reaction interface promotes the change of surface structure and bulk structure for LiNi0.6Co0.2Mn0.2O2, resulting in poor cycling stability that hindered its practical application. Here, the LiNi0.6Co0.2Mn0.2O2 surface modified by hybrid coating layer (NCM@LSAO) is reported. In this constructed hybrid layer, the LiAlO2 with layered structure can be firmly anchored on the NCM surface, and Si1–xAlxO2 with high electrical conductivity and chemical stability can be used as a protective layer to inhibit the occurrence of surface side reactions. Hence, combining the advantages of the LiAlO2 and Si1–xAlxO2 coating layer, which can effectively suppress the structural transformation and surface reaction interface failure upon long cycling, thus has improved the electrochemical performance accordingly. As a result, LiAlO2/Si1–xAlxO2 surface-modified LiNi0.6Co0.2Mn0.2O2 exhibits excellent rate performance, with a high discharge specific capacity of 153.4 mAh/g even at 10 C. In addition, the cyclic stability is also much improved, which can deliver a high discharge capacity of 130.1 mAh/g after 500 cycles at 5 C, with a capacity retention of 78.5%.