Comparison of Synthesized Microstructured and Commercial FePO4 as Precursors for High-Performance LiFePO4/C Cathode Materials

Abstract In recent years, lithium iron phosphate (LiFePO4, LFP) has attracted considerable attention as a cathode material for lithium-ion batteries due to its thermal stability, long cycle life, and low cost. The principal objective of this work was to evaluate the influence of different iron phosphate precursors on the synthesis and electrochemical performance of LiFePO4/C prepared by a solid-state route. A microstructured FePO4 obtained by controlled precipitation (FP-S) was compared with two commercially available FePO4 samples (FP-B1 and FP-B2) and with a synthesis route based on FeSO4 (FS). All materials showed the formation of phase-pure olivine LiFePO4, as confirmed by X-ray diffraction (XRD). However, significant differences in particle morphology and crystallinity were observed depending on the precursor source. The material derived from FP-S presented a more homogeneous particle size distribution (2–6 μm) and lower degree of agglomeration compared to the samples obtained from commercial phosphates. Electrochemical performance was evaluated under identical conditions. The best result, in terms of discharge capacity, was 158 mAh/g at 0.1C for the material derived from FP-S. The improved electrochemical response observed for the material prepared from the synthesized FePO4 indicates that precursor particle size control plays an important role in defining the final microstructure and electrode kinetics. These results suggest that laboratory-designed FePO4 precursors can provide better performance consistency than commercially available phosphates, where particle size distribution and morphological control are not well-defined.