Enhancing the structural and interfacial durability of Ni-rich cathodes under extended operating conditions via Mg/Zr/Nb tri-doping

Mg/Zr/Nb tri-doping jointly stabilizes Ni-rich layered cathodes under harsh operating conditions. • Tri-doping reduces Li + /Ni 2+ mixing and stabilizes the transition-metal layer and oxygen framework. • MZN-NCM delivers excellent cycling stability at room temperature, high temperature, and high cutoff voltage. • Mg/Zr/Nb co-doping improves charge transfer and Li + diffusion, enhancing the durability of Ni-rich cathodes. Ni-rich layered cathode materials (LiNi x M 1-x O 2 , x ≥ 0.8) offer high capacity and high energy density, but their cycling stability severely suffers from Li + /Ni 2+ cation mixing, H2-H3 phase-transition strain, interfacial side reactions, and sluggish Li + transport, especially under harsh conditions such as elevated temperature and high cutoff voltage. In this work, a Mg/Zr/Nb tri-doping strategy is proposed to construct Li(Ni 0.9 Co 0.05 Mn 0.05 ) 0.97 Zr 0.01 Mg 0.01 Nb 0.01 O 2 (MZN-NCM) cathode for synergistic stabilization under different operating conditions. The results show that Mg/Zr/Nb co-doping regulates the Ni valence distribution, reduces Li + /Ni 2+ cation mixing, enhances the stability of the transition-metal layer and oxygen framework, and suppresses interfacial side reactions and CEI degradation during cycling. MZN-NCM retains 90.1% of its capacity after 100 cycles at 25 °C and 89.8% at 60 °C, compared with only 59.8% and 41.7% for Pristine-NCM, respectively. Under a high cutoff voltage of 4.5 V, MZN-NCM also maintains a higher capacity retention of 87.7% after 100 cycles. Moreover, kinetic and interfacial chemical analyses indicate that multielement doping improves both charge-transfer behavior and Li + diffusion, enabling a synergistic enhancement of structural stability, interfacial stability, and ion transport. This work demonstrates that Mg/Zr/Nb synergistic doping is an effective material-design strategy for extending the applicable operating conditions of Ni-rich cathodes.