The influence of surface lithium residue to the performance of LiNi0.9Co0.05Mn0.05O2 cathode materials

High nickel ternary cathode materials (Ni ≥ 90%) have great potential for application as power batteries in electric vehicles and have become a hot spot for research on cathode materials. However, the residual Li on the surface of the high Ni ternary cathode materials prepared by solid-phase sintering is one of the main reasons affecting their electrochemical performance. It is found that Li1 + x(Ni0.9Co0.05Mn0.05)1-xO2 with x = 0.3, which has a discharge-specific capacity of 205.74 mAh g−1 at 2.7–4.3 V, 0.1C and 184.1 mAh g−1 at 1 C, retained 89% of its initial discharge capacity after 100 cycles at 1 C. The discharge-specific capacity at 10 C was 153.14 mAh g−1. In addition, the Li residue of NCM90-1.03 was 17,189.959 ppm, and the total alkalinity was 4196.896 ppm. The results by X-ray diffraction (XRD) and scanning electron microscope (SEM) showed that when the Li excess was 0.3%, it was possible to obtain uniform particle size, a wider Li layer, and reduced cation mixing. Therefore, choosing the right amount of excess Li can stimulate the application prospect of NCM90 in new energy vehicles.