Performance characteristics of lithium vanadium phosphate as a cathode material for lithium-ion batteries

The properties of the monoclinic lithium vanadium phosphate, Li3V2(PO4)3 (LVP), are investigated using X-ray diffraction (XRD) and electrochemical methods. Electrochemical measurements conducted in half cells with Li3V2(PO4)3 as the cathode material and lithium metal as the anode have shown that this material exhibits an excellent reversibility when the charge extracted is confined to that equivalent to two lithiums per formula unit. The extraction of the last lithium is observed at a potential >4.6 V versus Li/Li+ and involves a significant overvoltage. Upon discharge, a solid solution behavior is observed after which the two-phase regime for the last lithium insertion reappears. Furthermore, XRD has shown that the original structure is recovered. Cycling performance as well as rate capability are also presented for rocking-chair batteries based on LVP and graphite.