V2O3–Li3PO4 Composite: A New Type of Cathodic Active Material for Li-Ion Batteries

A new type of cathodic active material for lithium-ion batteries based on a composite of Li 3 PO 4 and V 2 O 3 is proposed in this work. Although the V 2 O 3 component is almost inactive in the voltage range of 2–4.5 V versus Li + /Li, the mixture of the two components can deliver a larger reversible specific capacity of ≈190 mA h g −1 in the voltage range of 2–4.5 V at a current density of 15 mA g −1 . X-ray photoelectron spectroscopy data and cyclic voltammetry data suggest that the vanadium ions are probably oxidized and reduced repetitively upon cycling and that the V 3+ ions are partially oxidized to V 4+ and even V 5+ ions during charging to 4.5 V. This distinctive lithium-ion uptake and release phenomenon, in which Li 3 PO 4 functions as a lithium source of surface conversion reaction, will introduce a new path for designing unique cathodic active materials for lithium-ion batteries.