Ultra‐Fast Charging High‐voltage Spinel LiNi0.5Mn1.5O4 Batteries Enabled by Mn─O Bond Regulating Strategy to Defeat Jahn─Teller Distortion

Abstract

The high‐voltage spinel LiNi0.5Mn1.5O4 (LNMO) is a promising cathode material for lithium‐ion batteries due to its high energy and power densities, excellent thermal stability, low cost, and environmental benignity. However, the presence of Mn3+ induces Jahn─Teller (J─T) distortion, leading to Mn─O bond elongation, lattice stress, and degradation of both structural and electrochemical stability during cycling. To address this,a bond‐length engineering strategy is proposed by co‐doping Fe at the Mn 16d sites and Sb at the vacant 16c positions to suppress the J─T effect and stabilize the crystal structure. Electron paramagnetic resonance (EPR), in situ X‐ray diffraction (XRD), and density functional theory (DFT) calculations confirm that the Mn─O bond regulation strategy effectively mitigates MnO6 octahedral distortion, reduces phase transitions, and enhances structural robustness. Moreover, Sb incorporation expands the lattice, facilitating Li+ diffusion. As a result, the optimized FeSb‐LNMO delivers remarkable electrochemical performance, retaining 98% of its initial capacity after 200 cycles at 1C, and achieving 85.6% capacity retention over 1000 cycles at 5C. This work introduces a novel bond‐length engineering approach via multi‐site doping to overcome degradation in high‐voltage LNMO, enabling ultra‐fast charging and long‐term cycling stability.