Nb-doped NCM622 shows improved capacity under high-temperature cycling—An experimental and theoretical study

Ni-rich layered lithiated transition metal oxide LiNi0.6Co0.2Mn0.2O2 (NCM622) is a promising candidate for Li-ion batteries. However, the high nickel content in NCM622 leads to significant capacity degradation during battery cycling. In this study, we investigated the effectiveness of niobium (Nb) doping in enhancing the performance of NCM622. Our findings demonstrate that Nb-doping reduces cation mixing and preserves the solid solution state of NCM622, as confirmed by calculated formation energy. Furthermore, the introduction of Nb imparts remarkable electrochemical properties to the material. Even under high-temperature and high-voltage conditions, the Nb-doped sample exhibits significantly improved cycling performance compared to the undoped sample, starting from the fifth cycle onwards. Through a combination of atomic-level mechanisms and experimental techniques, this research establishes that Nb-doping can enhance the structural stability and electrochemical properties of NCM622, providing a viable pathway for the industrial advancement of Ni-rich materials.