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

Oxygen deficient Li1+xV3O8-delta (0.03 < delta< 0.2) is prepared by reduction of Li1+xV3O8 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-delta 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-delta 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.