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

The profile of Fe-incorporation into carbon-coated Li 3 V 2 (PO 4 ) 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 Li 3+ x V 2– y Fe 2+ y (PO 4 ) 3 , LiFePO 4 and FePO 4 in the Fe-incorporated LVP/C composite. The FePO 4 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.