Structural and electrochemical characterization of LiMn2−δVδOy spinels

The spinel phase compounds with the composition of LiMn2−δVδOy were prepared by solid reaction of the mixture of LiNO3·H2O, MnCO3 and NH4VO3 powders. Evolution of the crystalline phases of the samples versus the vanadium content was analyzed using X-ray diffraction (XRD) technique, EPR and FT-IR spectroscopes. Cubic spinel is the predominant phase in the powders under heat treatment at 550 °C for 5 h. The valence state of manganese ion changed from +4 to +3 with vanadium substitution for charge compensation. The vanadium substitution of manganese leads the decline in capacity and cyclic behavior of the powders. The electrochemical behaviors relating to the variation of structure corresponding to the vanadium substitution were discussed.