Double-shelled nanocapsules of V2O5-based composites as high-performance anode and cathode materials for Li ion batteries.

Double-shelled nanocapsules of V(2)O(5)-SnO(2) composites were chemically assembled via a one-pot solution method. These hollow nanocapsules are composed of a double-shelled V(2)O(5) matrix that includes a low weight ratio of SnO(2) (e.g., 10 or 15%). In these double shells, open-structured V(2)O(5) acts as not only a supporting matrix but also an active electrode component. The gap between the two shells and the hollow cavity provide sufficient space for volume variation during conversion reactions and lithium alloying/dealloying processes. As a promising anode electrode, this nanocomposite shows a large, reversible capacity of 947 mA h g(-1) at a rate of 250 mA g(-1) and retains a high capacity of 673 mA h g(-1) after 50 cycles. Even at a high rate of 2500 mA g(-1), the current nanocomposite electrode can still deliver a reversible capacity of 505 mA h g(-1). As a cathode electrode, our nanocomposite shows not only a high reversible capacity of approximately 250 mA h g(-1) but also good cycling and rate capability.