Surface Engineering of Ni-Rich Cathodes Enables Homogeneous Doping of High-Valence Mo Ions for Li-Ion Batteries

Doping high-valence metal ions into Ni-rich cathodes is a crucial strategy to improve their cycling stability, but they usually form a gradual element distribution near the surface with intergranular accumulations dominantly, owing to their large ionic radius and high diffusion energy barriers. Herein, we demonstrate the synthesis of homogeneous Mo doped Ni-rich cathodes (Mo-NCM83(H)) by first forming Mo-involved compounds on the surface of the precursor and subsequent high-temperature diffusion strengthening. The Mo-doping induces the formation of the radially arranged and elongated primary particles, and the strong Mo–O bonds greatly reduce the lattice oxygen loss at high states of charge in the meantime. These merits effectively alleviate the stress concentration and interface side reactions, ultimately enhancing the cycle stability. In consequence, the as-obtained Mo-NCM83(H) gives a high-capacity retention rate of 99.7% at 1C after 100 cycles and a rapid charge capability of 125 mAh g–1 at 10C. This work provides a feasible strategy to realize the high-efficiency high-valence ions doping with uniform distribution for Ni-rich cathodes.