Studies on elechtrochemical behaviour of zinc-doped LiFePO4 for lithium battery positive electrode

Authors

Atef Y. Shenouda, Central Metallurgical Research and Development Institute, EgyptFollow
Hua-Kun Liu, University of WollongongFollow

RIS ID

31542

Publication Details

Shenouda, AY & Liu, HK (2009), Studies on elechtrochemical behaviour of zinc-doped LiFePO4 for lithium battery positive electrode, Journal of Alloys and Compounds, 477(1-2), pp. 498-503.

Abstract

The effects of zinc oxide doping on LiFePO₄ have been studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and galvanostatic measurements. The XRD patterns demonstrate that the samples have the phase of LiFePO₄ with an ordered olivine structure indexed to the orthorhombic Pmna space group. Also, XRD patterns show with the presence of LiZnPO₄ phase for zinc oxide doped samples. The EIS results showed that the conductivity is enhanced by zinc oxide doping. The 2.5% ZnO-doped LiFePO₄ demonstrated higher conductivity than the 1.5% ZnO and 5% ZnO-doped LiFePO₄ or the un-doped sample. The CV curves show that 2.5% ZnO-doped LiFePO₄ has higher electrochemical reactivity for lithium insertion and extraction than the un-doped material. The mean redox potential is E_1/2 = 3.45 V vs. Li⁺/Li. The first discharge curve of the 2.5% ZnO-doped LiFePO₄ shows a mainly flat voltage plateau over the 3.45–3.5 V range, indicating the lithium extraction and insertion reactions between LiFePO₄ and FePO₄. A specific discharge capacity of about 177 mAh g⁻¹ was achieved, with little decrease during cycling.