New Cathode Material of VOPO4 For Li Ion Rechargeable Battery

Cathodic performance of seven different VOPO4 phases for Li ion rechargeable battery was investigated. It was found that VOPO4 exhibits a high flat potential of 3.7V and 3.9V for Li ion electrochemical intercalation and de-intercalation excepting for b and e-types. Capacity for li intercalation is strongly related with crystal structure of VOPO4. In particular, d-VOPO4 exhibits the largest reversible capacity ca. 130 mhA/g among the examined VOPO4. High capacity for Li intercalation in d-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/cm2 for d-type VOPO4. In order to increase the capacity in d-phase VOPO4, synthesis condition was further studied. It was found that synthesis d-phase VOPO4 in ethanol give a fine powder of VOPO4 resulting in the increased capacity for Li intercalation.