Enabling Ultrahigh-Power-Density LiMn _0.6 Fe _0.4 PO ₄ Cathodes via Kinetics Limitation Breakthrough and Jahn–Teller Distortion Mitigation

Development of high-power LiMn x Fe 1-x PO 4 (LMFP) cathodes is fundamentally challenged by the interplay between sluggish one-dimensional Li + diffusion and severe Jahn–Teller distortion. Herein, we propose a synergistic substitution strategy to concurrently tackle these issues. Partial replacement of PO 4 tetrahedra by planar BO 3 groups creates three-dimensional interconnected Li-ion diffusion networks, while doping Nb 5+ into transition-metal sites widens the diffusion channels. This tailored microstructure not only overcomes the intrinsic Li + diffusion kinetics limitation but also dissipates the mechanical stress arising from high-rate operating conditions, suppressing the Jahn–Teller distortion in MnO 6 octahedra by 36%. The optimized LMFP cathode delivers an ultrahigh reversible capacity of 126 mAh g –1 at 10C (about a 3.6-fold improvement over the pristine LMFP) and retains 80.2% of its initial capacity after 2000 cycles at 3C in pouch-type full cells. This work elucidates the critical link between Li + diffusion kinetics and structural stability, providing an available paradigm for designing high-power, long-life Mn-based cathode materials.