Improving the Electrochemical Performance of Core–Shell LiNi0.8Co0.1Mn0.1O2 Cathode Materials Using Environmentally Friendly Phase Structure Control Process

The phase structure of the precursor is crucial for the microstructure evolution and stability of Ni-rich cathode materials. Using sodium lactate as a green complexing agent, cathode electrode materials with different phase structures and unique core–shell structures were prepared by the co-precipitation method in this study. The influence of the phase structure of the nickel-rich precursor on the cathode electrode materials was studied in depth. It was found that α-NCM811 had large interlayer spacing, which was beneficial for the diffusion of lithium ions. In contrast, β-NCM811 had smaller interlayer spacing, a good layered structure, and lower ion mixing, resulting in better cycling performance. The core–shell-αβ-NCM811 with α-NCM811 as the core and β-NCM811 as the shell was prepared by combining the advantages of the two different phases. The core–shell-αβ-NCM811 showed the highest discharge capacity of 158.7 mAh/g at 5 C and delivered excellent rate performance. In addition, the β-NCM811 shell structure with smaller layer spacing could prevent corrosion of the α-NCM811 core by the electrolyte. Thus, the capacity retention rate of the core–shell-αβ-NCM811 was still as high as 86.16% after 100 cycles.