The Mg-V2O5 Intercalation Phase Diagram First Principles

Wednesday, October 14, 2015: 12:00
102-C (Phoenix Convention Center)
G. S. Gautam, P. Canepa, A. Abdellahi, A. Urban, R. Malik (Massachusetts Institute of Technology), and G. Ceder (Massachusetts Institute of Technology)
Multi-valent (MV) ion intercalation batteries that replace the Li+ with a MV cation such as Mg2+, provide a realistic and compelling approach to meet the high energy density demanded by the next generation of electronics and vehicles. One of the challenges in achieving high energy density MV-ion systems is to develop a suitable cathode with a high enough voltage and diffusivity of the MV cation. Mg intercalation into V2O5 is one of the very few that has been shown to function reversibly at reasonable efficiency. In this study, we gain insight into the thermodynamics of Mg insertion into V2O5 from first-principles calculations.  We have calculated the 0 K phase diagram, the equilibrium voltage curves and the migration barriers for Mg diffusion in both the α and δ-V2O5 polymorphs. Our calculations indicate that Mg in V2O5 is a “phase separating” system at room temperature and benchmarking our calculations with experiments leads to the conclusion that Mg cycles on a metastable α-V2O5 host. We believe that this study can be further used to improve the performance of V2O5 as a cathode material for Mg-batteries.