Constructing defect-rich in-situ N-doped carbon coating via a PVP-assisted strategy for enhanced electrochemical performance in LiMn0.5Fe0.5PO4 cathodes

LiMn x Fe 1−x PO 4 (LMFP) has emerged as a promising next-generation cathode material for lithium-ion batteries (LIBs), characterized by its high energy density and exceptional thermal stability. However, its intrinsically poor electronic conductivity and Jahn-Teller effect induced by Mn 3+ severely limit rate capability and cycle life. Unlike previously reported LMFP/N-doped carbon systems, herein an in situ defect-rich nitrogen-doped carbon coating is constructed on LiMn 0.5 Fe 0.5 PO 4 (LMFP/C-xN) via a high-temperature solid-state method using PVP as the bifunctional dispersant and carbon/nitrogen source. An optimal PVP dosage of 10 wt% effectively refined the particle size and improved morphological uniformity. Characterization and electrochemical tests revealed that nitrogen doping of the carbon coating introduces abundant defect sites, enhancing electronic conductivity and Li + diffusion kinetics, while the PVP-derived carbonization partially reduces Mn 3+ to mitigate Jahn-Teller distortion. LMFP/C-10N delivered a high discharge capacity of 164.9 mAh g − 1 at 0.1 C and retained 94.5% capacity after 300 cycles at 4 C. This work provides a facile PVP-assisted strategy for high-performance long-life LMFP cathodes, outperforming most previously reported LMFP/N-doped carbon cathodes.