Synthesis and Electrochemical Performance of Mn-Doped LiFePO₄ Cathodes for Lithium-Ion Batteries

Abstract

Lithium iron phosphate (LiFePO₄) is a widely studied cathode material for lithium-ion batteries due to its stability and safety. However, its limited electrical conductivity restricts capacity at high charge/discharge rates. In this study, Mn-doped LiFePO₄ was synthesized via solid-state reaction, and its structural and electrochemical properties were evaluated. X-ray diffraction confirmed phase-pure olivine structure with slight lattice expansion upon Mn incorporation. Scanning electron microscopy showed homogeneous particle distribution with average sizes around 200 nm. Electrochemical impedance spectroscopy demonstrated reduced charge-transfer resistance, attributed to improved electronic conductivity. Galvanostatic charge-discharge testing revealed that Mn-doped samples achieved a specific capacity of 158 mAh/g at 0.1C and retained 90% of capacity after 300 cycles at 1C, outperforming pristine LiFePO₄. Rate performance tests indicated superior stability at high current densities. These results highlight Mn doping as an effective strategy for enhancing LiFePO₄ cathodes, contributing to improved lithium-ion battery performance for electric vehicle and grid storage applications.