Extended Limits of Reversible Electrochemical Lithiation of Crystalline V 2 O 5

Although lithium intercalation into vanadium (V) oxide was studied over decades, exact compositional stability limits for γ‐Li_xV₂O₅ 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.