Improving the cycling and air-storage stability of LiNi0.8Co0.1Mn0.1O2 through integrated surface/interface/doping engineering

Abstract

The poor cycling performance and storage instability of Ni-rich layered oxide cathode materials seriously restrict their practical application. Herein, we report to improve the cycling and air-storage stability of LiNi_0.8Co_0.1Mn_0.1O₂ through integrated surface/interface/doping engineering. The capacity retention after 500 cycles at 5C is largely enhanced from 69.6 to 80.6%. After 70 days of storage in air, the initial discharge capacity at 5C is 143.1 mA h g⁻¹ and the capacity retention after 500 cycles is 88.5%. The cycling and air-storage stability can be attributed to the integration of the Li₂ZrO₃ protective layer, Zr⁴⁺ doping and the rock-salt interface phase from Li₂ZrO₃ coating. The Li⁺-conductive Li₂ZrO₃ layer suppresses the side reaction as well as enhances the Li-ion diffusion at the interface. In the meantime, Zr⁴⁺ doping enlarges the lithium slab thickness and decreases Li/Ni disorder, which further enhances Li-ion diffusion in the bulk. Zr⁴⁺ doping makes TM–O bonds more stable and alleviates the lattice changes during charge–discharge cycles owing to the strong Zr–O bond. Moreover, the formed rock-salt phase on the interface further enhances the stability of the layered structure. More importantly, the Li₂ZrO₃ coating suppresses the formation of an electrochemically insulating substance on the cathode surface, which dramatically improves the long term air-storage stability.