Extended Limits of Reversible Electrochemical Lithiation of Crystalline V2O5

Although lithium intercalation into vanadium (V) oxide was studied over decades, exact compositional stability limits for gamma-LixV2O5 phase, which can be reversibly lithiated and delithiated, are still not clear. Using operando and ex-situ synchrotron X-ray diffraction, we traced phase composition of the V2O5 electrodes containing reduced graphene oxide during its lithiation and delithiation. We found that coating of micron-sized V2O5 particles by reduced graphene oxide yields the material providing electrochemical capacity of more than 300 mA h g(-1) manifesting insertion of more than 2 lithium ions per mole of V2O5 as confirmed by ICP MS analysis of the electrodes. The obtained electrode material can be sustainably cycled with capacity retaining at ca. 220 mA h g(-1) at 500 mA g(-1) current over 200 cycles.