LiFePO 4 /C material has been prepared using fastmelt synthesis method followed by grinding and carbon coating. The low-cost iron ore concentrate (IOC) and purified iron ore concentrate (IOP) were used as iron precursors in the melt process to reduce significantly the cost of LiFePO 4 /C. The same product was also synthesized using pure Fe 2 O 3 under similar conditions as reference. The physical-chemical and electrochemical properties of samples were investigated. The X-ray Diffraction (XRD) results confirm the formation of an olivine structure of LiFePO 4 with a minor amount of Li 3 PO 4 and Li 4 P 2 O 7 impurities for all the samples but no Fe 2 P. The power performances of LiFePO 4 /C using low-cost iron precursors were close to the sample using pure Fe 2 O 3 precursor although capacity in mAh g −1 is somewhat lower. With the inherent presence of silicon and other metals species, multisubstitution may take place when using IOC as source of iron leading to a Li(Fe 1-y M y )(P 1-x Si x )O 4 general composition. Multi-substitution, however, allows a better cycling stability. Therefore, these iron precursors present a promising option in this field to reduce the cost of a large-scale synthesis of LiFePO 4 /C for Li-ion batteries application.
Development of LiFePO 4 cathode material with high cycle life through Si doping (substituting Si at P sites of LiFePO 4 ) has shown that small changes to the structure of LiFePO 4 can significantly affect the performance of Li ion batteries. However, determining the nature of elemental doping and their effects on the electronic and atomic structure of LiFePO 4 remains challenging. Here we present x-ray absorption spectroscopy and x-ray fluorescence mapping as ideal characterization methods for understanding the effect of Si doped LiFePO 4 prepared using a melt-synthesis process.x-ray absorption spectra of silicon doped LiFePO 4 indicate subtle changes in the local structure surrounding the dopants compared to SiO 2 and amorphous glass phases formed as impurities in Si containing undoped samples. The study of Fe and P K-edges x-ray absorption spectra illustrates the effect of Si in the LiFePO 4 structure in doped and impurity containing samples. Utilizing x-ray absorption spectroscopy, in conjunction with x-ray fluorescence mapping, has enabled a better overview of the non-uniform nature of prepared ingot samples. These results highlight the power of x-ray absorption spectroscopy as a tool for better understanding the structure of modified LiFePO 4 and subsequently designing materials for Li ion batteries.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.