Synthesis and characterization of LiFePO 4 /C using low iron ion solution by goethite method

Iron is commonly present as an impurity or by-product in various smelting processes. In this study, the separation and purification of iron from a zinc wet smelting leaching solution were achieved using the goethite method, which involved controlling pH and adding crystal seeds. The separated iron was then utilized as the iron source for the preparation of LiFePO 4 /C (lithium iron phosphate) in the form of α-FeOOH. Subsequently, LiFePO 4 /C was synthesized through wet ball milling and carbon thermal reduction. The physicochemical and electrochemical properties of the material were characterized using several techniques, including inductively coupled plasma-optical emission spectrometry (ICP-AES), X-ray diffractometer (XRD), field emission scanning electron microscopy (SEM), transmission electron microscope (TEM), thermogravimetric differential thermal analyzer (TG/DTA), Fourier exchange infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), and electrochemical techniques. The results indicate that the LiFePO 4 /C prepared using the goethite method exhibits excellent cycling properties and stability. The initial discharge capacities at various rates (0.1 C, 0.2 C, 0.5 C, 1 C, 2 C, and 5 C) were measured as 149.5, 142.6, 135.6, 131.7, 116.5, and 102.5 mAh g −1 , respectively. Impressively, after 200 cycles at 1 C, the material retained 99.5% of its initial capacity. Furthermore, even after 1000 cycles at a current rate of 1 C, it still maintained 95.4% of its capacity. Therefore, this study presents a novel technical route for the recovery and recycling of iron ions, while also demonstrating the promising performance of LiFePO 4 /C.