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

The high-voltage spinel LiNi 0.5 Mn 1.5 O 4 (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 Mn 3+ 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 MnO 6 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.