Understanding the Role of Various Dopant Metals (Sb, Sn, Ga, Ge, and V) in the Structural and Electrochemical Performances of LiNi0.5Co0.2Mn0.3O2

Ni-rich layered oxides have been widely applied commercially due to their high energy density and capacity. However, there are still some drawbacks of capacity fading, O2 release, and Li/Ni exchange. Cation doping has been proven to be one of the most promising strategies to improve the electrochemical performances of Ni-rich layered oxides. Herein, density functional theory (DFT) calculations have been performed to investigate the effects of doping various cations (Sb5+, Sn4+, Ga3+, Ge4+, and V5+) on the structural stability and electrochemical performances of LiNi0.5Co0.2Mn0.3O2 (NCM523). The theoretical results show that Sb, Sn, Ga, Ge, and V doping can reduce the oxidation state of Ni ions. Moreover, doping with these metals can inhibit O2 release and Li/Ni exchange, which improves the safety, capacity retention, and rate capacity. Furthermore, Ga and Ge doping can improve the stability of partially deintercalated states, suppress lattice distortion, and increase the intercalation voltage. In conclusion, Ga and Ge doping is an effective strategy to optimize the electrochemical performances of NCM523.