Electrochemical and structural characteristics of niobium vanadium oxide electrodes in a secondary lithium battery

The electrochemical behavior and structural changes of several Nb2−xVxO5(x=0.2–1.0) were investigated in 1 M LiClO4-propylene carbonate solution as positive electrodes for rechargeable lithium batteries. Using the electrochemical measurements, X-ray diffractometry and X-ray photoelectron spectroscopy (ESCA), the possible electrode reaction with discharge and recharge is shown as follows: Nb2−xVxO5(x=0.2–1.0)+nLi++ne−αLinNb2−xVxO5. The discharge reaction consists of two main steps. In the first step, a ternary phase LinNb2−xVxO5(x=0.5–1.0) with a varying nvalue is formed, and in the second ternary phase LinNb2−xVxO5(x=0.5–1.0) with a varying nvalue is formed, and in the second ternary phases LinNb2−xVxO5with different constant nvalues may be formed. Good charge-discharge cycling behavior was obtained with the oxides having a higher xvalue (0.7–0.8), which showed a small crystal lattice change along the aand caxes, while keeping the original lattice arrangement during cycling.