The Intercalation Phase Diagram of Mg in V2O5 from First-Principles.

S. G. Gautam, P. Canepa, A. Abdellahi, A. Urban, R. Malik, G. Ceder.; Chem. Mater. 27 (10), 3733–3742 (2015).

Abstract

We have investigated Mg intercalation into orthorhombic V2O5, one of only three cathodes known to reversibly intercalate Mg ions. By calculating the ground-state MgxV2O5 configurations and by developing a cluster expansion for the configurational disorder in δ-V2O5, a full temperature–composition phase diagram is derived. Our calculations indicate an equilibrium phase-separating behavior between fully demagnesiated α-V2O5 and fully magnesiated δ-V2O5, but also motivate the existence of potentially metastable solid solution transformation paths in both phases. We find significantly better mobility for Mg in the δ polymorph, suggesting that better performance can be achieved by cycling Mg in the δ phase.