Preparation and characterization of Li$_{1-3x}$Cr$_{x}$FePO$_{4}$ cathode materials for lithium ion batteries

Cr-doped LiFePO$_{4}$ cathode materials have been synthesized by solid-state reaction method and characterized by and specific capacity, synchrotron-based in-situ energy dispersive x-ray diffraction (EDXRD), and x-ray absorption (XAS) measurements. It is found that with the increase of the concentration of the doped-Cr, the specific capacity decreases. The specific capacity decreases with increasing charge/discharge rate. XAS result shows that Cr in the cathode materials is in trivalent state. The in-situ EDXRD measurement on Cr-doped LiFePO$_{4}$ coin cell batteries shows that EDXRD is an excellent technique for studying internal layer structure and chemical reactions in Li-ion batteries with thick metallic walls.