Enabling Ultrahigh-Power-Density LiMn_0.6Fe_0.4PO₄ Cathodes via Kinetics Limitation Breakthrough and Jahn-Teller Distortion Mitigation.

Abstract

Development of high-power LiMn_xFe_1-xPO₄ (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 PO₄ tetrahedra by planar BO₃ groups creates three-dimensional interconnected Li-ion diffusion networks, while doping Nb⁵⁺ 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 MnO₆ 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.