Novel synthesis of 3D mesoporous FePO₄ from electroflocculation of iron filings as a precursor of high-performance LiFePO₄/C cathode for lithium-ion batteries

This study presents an economic and environmentally friendly method for the synthesis of microspherical FePO₄·2H₂O precursors with secondary nanostructures by the electroflocculation of low-cost iron fillers in a hot solution. The morphology and crystalline shape of the precursors were adjusted by gradient co-precipitation of pH conditions. The effect of precursor structure and morphology on the electrochemical performance of the synthesized LiFePO₄/C was investigated. Electrochemical analysis showed that the assembly of FePO₄·2H₂O submicron spherical particles from primary nanoparticles and nanorods resulted in LiFePO₄/C exhibiting excellent multiplicity and cycling performance with first discharge capacities at 0.2C, 1C, 5C, and 10C of 162.8, 134.7, 85.5, and 47.7 mAh·g^-1, respectively, and the capacity of LiFePO₄/C was maintained at 85.5% after 300 cycles at 1C. The significant improvement in the electrochemical performance of LiFePO₄/C was attributed to the enhanced Li⁺ diffusion rate and the crystallinity of LiFePO₄/C. Thus, this work shows a new three-dimensional mesoporous FePO₄ synthesized from the iron flake electroflocculation as a precursor for high-performance LiFePO₄/C cathodes for lithium-ion batteries.