Enhanced rate performance of LiFePO4/C by co-doping titanium and vanadium

By Yun-Fei Long and Jing Su and Xiao-Ru Cui and Xiao-Yan Lv and Yan-Xuan Wen
Published in Solid State Sciences NULL 2015

Abstract

V and Ti co-doped LiFePO4/C composites were synthesized by a wet milling assisted carbothermal reduction technology. The structure, morphology and electrochemical performance of the samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), magnetic susceptibility, positron annihilation lifetime spectra (PAS), scanning electron microscope (SEM), charge/discharge tests, electrochemical impedance spectroscopy (EIS) and cyclic voltammograms (CV). The results showed that the V and Ti co-doped samples kept the olivine structure of LiFePO4, but the synergistic effects between V3+ and Ti4+ in the lattice can increase the disorder degree of the lattice and create Li+ vacancies in LiFePO4/C, thus improve electronic conductivity and Li+ diffusion coefficient. LiV0.069Ti0.025Fe0.905PO4/C delivers an initial discharge capacity of 144.1

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