Understanding the Role of Nb Doping in Modulating Ionic Diffusion Kinetics and Particle Size in Spinel LiMn ₂ O ₄

ABSTRACT The increased primary particle size generally leads to reduced electrochemical performance of electrode materials in Li‐ion batteries. Herein, we report the simultaneous achievement of enhanced rate performance and increased particle size in spinel LiMn 2 O 4 (LMO) through niobium (Nb) incorporation. After Nb incorporation, the surface energies of the (100), (110), and (111) crystal planes are significantly reduced, resulting in the formation of larger particles. Moreover, Nb doping increases the lattice parameter of the spinel structure, thereby facilitating Li + transport and reducing polarization. Electrochemical tests demonstrate that the LMO cathode with 0.4 wt.% Nb delivers an initial discharge capacity of 130 mAh g −1 and retains 93.9% of its capacity after 100 cycles at 1 C and 45°C.