Cathodic performance Of VOPO4 with various crystal phases for Li ion rechargeable battery

Cathodic performance of six different VOPO4 phases for Li ion rechargeable battery was investigated. It was found that VOPO4 exhibits a high flat discharge potential of 3.7 V for Li ion electrochemical intercalation and de-intercalation excepting for beta- and epsilon-types. On the other hand, slightly higher flat discharge potential of 3.9 and 3.8 V was observed for beta- and epsilon-types. Capacity for Li intercalation is strongly related with the crystal structure Of VOPO4. In particular. delta-phase exhibits the largest reversible capacity of ca. 130 mAh/g among the examined VOPO4. High capacity for Li intercalation in delta-phase VOPO4 hardly decreased over 30 times of charge and discharge cycles. Although the reversible capacity decreased with increasing the current density for charge and discharge, large capacity of 80 mAh/g was still sustained at 0.4 mA/cm(2) for delta-type VOPO4. (C) 2002 Elsevier Science Ltd. All rights reserved.