Insight into Fe Incorporation in Li₃V₂(PO₄)₃/C Cathode Material

Abstract

The profile of Fe-incorporation into carbon-coated Li3V2(PO4)3 (LVP) cathode material for lithium ion batteries has been systematically investigated with X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectrometry and electrochemical measurements. The results confirm the coexistence of Li3+xV2–yFe2+y(PO4)3, LiFePO4 and FePO4 in the Fe-incorporated LVP/C composite. The FePO4 appears to be present as an amorphous phase associated with the carbon coat. Compared with pristine LVP/C, significant improvement in capacity, cycling stability, and rate capability in LVP/C-Fe were achieved, which is attributed to the reduced particle size, a decreased electrolyte/electrode charge-transfer resistance, and a suppressed electrolyte/electrode reaction at high voltage.