Effect of magnetic field on the rate performance of a Fe₂O₃/LiFePO₄ composite cathode for Li‑ion batteries

Abstract

Lithium iron phosphate (LiFePO₄ or LFP) is a widely used cathode material in lithium-ion batteries (LIBs) due to its low cost and environmental safety. However, LFP faces challenges during high-rate operation and prolonged cycling. Magnetic field (MF) can enhance ionic conductivity and reduce polarization in the LFP cathode, particularly when magnetically sensitive iron oxide is added to the cathode. In this study, LiFePO₄ was optimized by simply adding Fe₂O₃ (FO) nanoparticles and drying the composite cathode (FO/LFP) with and without applying MF. Electrochemical tests demonstrated that the optimized samples prepared at two concentrations of Fe₂O₃ (1 wt% and 3 wt%) exhibited improved electrochemical characteristics and inhibited polarization upon operation. Lithium-ion diffusion coefficient calculations revealed an increase in this value in the case of the MF-assisted samples compared to their non-MF counterparts. The 1 wt% FO/LFP cathode dried under an MF showed noticeably high reversible capacity, slow capacity decay, and enhanced rate capability, especially when cycled at a high current density of 5C. This research successfully demonstrated a relatively facile method to improve the rate performance of LiFePO₄ cathodes that can be easily incorporated into the large-scale battery production.