Achieving excellent cycling stability in LiNi0.9Co0.05Mn0.05O2 by Mg2+ doping

Abstract

High-nickel layered oxide cathodes with a nickel content of >80% exhibit high capacity and low cost, showing great potential for next-generation lithium-ion batteries (LIBs). However, high nickel content usually leads to the exacerbation of phenomena such as harmful phase transitions, micro-cracks, and cationic disordering in high-nickel cathode materials during the cycling process. In this work, the LiNi_0.9Co_0.05Mn_0.05O₂ (NCM) cathode material is modified by Mg²⁺ doping. The research results show that the incorporation of Mg²⁺ can enhance the order degree of the material and expand the interlayer spacing of the Li layer, which is beneficial to enhance Li⁺ diffusion and improve cycle performance. When the Mg²⁺ doping amount is 1%, at a current density of 0.1C, the initial specific discharge capacity is 210.05 mA h g⁻¹, and it is 187.60 mA h g⁻¹ after 100 cycles. The capacity retention rate reaches 89.31%, which is higher than that of NCM (77.97%). At a current density of 1C, the initial specific discharge capacity is 174.59 mA h g⁻¹, and it is 157.51 mA h g⁻¹ after 100 cycles. The capacity retention rate is 90.22%, which is higher than that of NCM (79.79%).