Optimizing NCM811 nickel-rich cathode stability via suppressing asymmetric Li/Ni mixing by a “non-intrusive” strategy

Abstract

Being one of the potential positive electrode materials for lithium-ion batteries, the reduced stability of nickel-rich layered oxides during long-cycle processes hinders their widespread commercial application. In this paper, a “non-invasive” structural optimisation strategy is proposed to improve the structural stability of LiNi_0.8Co_0.1Mn_0.1O₂. Inspired by the co-precipitation process, this study incorporates sodium sulfamate during the synthesis of nickel-rich precursors to impact the crystallization process. By doing so, the cathode material undergoes modification, resulting in augmented interlayer spacing and reduced lattice defects (caused by non-equivalent Li/Ni mixing), allowing polycrystalline particles to possess some of the structural advantages of single crystal particles, ultimately enhancing capacity and cycling stability. The retention rate of capacity for the modified cathode after 300 cycles can be elevated by approximately 20% relative to that of NCM811, while the residual capacity can be increased by roughly 40 mA h g⁻¹. The new “non-intrusive” structural optimization strategy proposed in this study has the characteristics of good compatibility, low cost, and environmental friendliness. At the same time, this strategy will help to explore new ideas for improving the properties and synthesis of nickel based materials.