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

Gautam, G. S.; Canepa, P.; Abdellahi, A.; Urban, A.; Malik, R.; Ceder, G.

doi:10.1021/acs.chemmater.5b00957

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

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

BibTeX

@article{Gautam2015intercalation,
  author  = {Gautam, G. S. and Canepa, P. and Abdellahi, A. and Urban, A. and Malik, R. and Ceder, G.},
  title   = {{The Intercalation Phase Diagram of Mg in V$_{2}$O$_{5}$ from First-Principles}},
  journal = {Chemistry of Materials},
  volume  = {27},
  pages   = {3733--3742},
  year    = {2015},
  doi     = {10.1021/acs.chemmater.5b00957}
}

Brief summary

V₂O₅ is one of only three known positive electrodes that reversibly take up magnesium ions. We compute its full phase diagram as magnesium is added and find that magnesium moves much faster in its δ form, suggesting that batteries would perform better if they cycled magnesium in that phase.

Full 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 Mg_xV₂O₅ 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.