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. 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 n value is formed, and in the second ternary phases LinNb2-xVxO5 with different constant n values may be formed. Good charge-discharge cycling behavior was obtained with the oxides having a higher x value (0.7-0.8), which showed a small crystal lattice along the a and c axes, while keeping the original lattice arrangement during cycling.