Electrolytic V2O5 materials were prepared by electrochemical oxidation of vanadyl ions in aqueous solution. The electrodeposition reaction includes two steps: an oxidation into soluble species followed by a precipitation. With the use of various electrodeposition conditions and subsequent heat treatment it is possible to obtain e-V2O5 compounds with different VIV and water contents.
e-V2O5 compounds are mixed valence, hydrated vanadic acids and their formula can be written as H0.4V2O5.2−δ.nH2 with 0.04<8<0.22 and 0<n<1.8. These poorly crystallized layered compounds undergo a phase transformation into α-V2O5 starting at 240°C.
The electrochemical intercalation of lithium into these compounds shows two main single phase phenomena at ≈3.2V/Li and ≈2.6V/Li. Their capacity retention is better than that of other V2O5 reference compounds, but the reversible capacity down to 2V is only ≈100Ah/kg at a rate faster than C/5, due to kinetic limitations.