Preparation and electrochemical studies of Y-doped LiVPO₄F cathode materials for lithium-ion batteries

Abstract

Y-doped LiVPO₄F cathode materials were prepared by a carbothermal reduction(CTR) process. The properties of the Y-doped LiVPO₄F samples were investigated by X-ray diffraction (XRD) and electrochemical measurements. XRD studies show that the Y-doped LiVPO₄F samples have the same triclinic structure as the undoped LiVPO₄F. The Li extraction/insertion performances of Y-doped LiVPO₄F samples were investigated through charge/discharge, cyclic voltammogram (CV), and electrochemical impedance spectra(EIS). The optimal doping content of Y is x=0.04 in LiY _xV_1−xPO₄F system. The Y-doped LiVPO₄F samples show a better cyclic ability. The electrode reaction reversibility is enhanced, and the charge transfer resistance is decreased through the Y-doping. The improved electrochemical performances of the Y-doped LiVPO₄F cathode materials are attributed to the addition of Y³⁺ ion by stabilizing the triclinic structure.

Keywords

lithium-ion batteries / cathode material / LiVPO₄F / Y-doping / carbothermal reduction method / cyclic voltammogram (CV)

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