Low-potential lithium-ion reactivity of vanadium oxide aerogels

Vanadium oxide aerogels are electrochemically lithiated to 0.1 V vs. Li/Li+, yielding reversible capacities of ∼1000 mAh g−1 at charge/discharge rates of C/10. This reversible behavior is significantly different from crystalline orthorhombic V2O5, which exhibits a constantly decreasing capacity with cycling. The ability of the aerogel material to be deeply cycled lies in its unique morphology: high surface area, interconnected porosity, and a fibrous network structure enable lithium storage to occur. Ex situ TEM and XPS measurements indicate, respectively, that the fibrous morphology is retained at low potentials and that the oxidation state of vanadium changes from +5 to +2 during the electrochemical cycling.