Preparation and lithium insertion behaviour of oxygen-deficient Li1 + xV3O8 − δ

Oxygen deficient Li1 + xV3O8 − δ (0.03 < δ<0.2) is prepared by reduction of Li1 + x V3O8 with carbon. From infrared spectroscopic (IR) studies, it is found that specific oxygen is removed from the host lattice. Electrochemical measurement reveals that more lithium is inserted in Li1 + xV3O8 − δ compared with original Li1 + xV3O8 contrary to a decrease in pentavalent vanadium V(V) by the introduction of oxygen defects. This is probably due to the formation of new sites available for the occupation of Li+ ions. During the oxidation process by charging of Li1 + xV3O8 − δ containing V(IV), Li+ ions are extracted from the octahedral sites and inserted at the initial stage of discharge process. These effects result in an increase in the total amount of inserted lithium.