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Magnesium-based batteries represent a promising post-lithium battery technology due to magnesium's low cost and high natural abundance. Among the few materials exhibiting good Mg ion conductivity, the spinel phase MgSc₂Se₄ stands out as a particularly promising solid electrolyte candidate.[1] While the bulk properties of MgSc₂Se₄ are already well understood, advancing toward practical applications requires comprehensive understanding of interface behaviour in complete battery systems. This work focuses on elucidating surface stability and restructuring phenomena of MgSc₂Se₄. We employed periodic density-functional theory to investigate experimentally relevant surface facets, providing insights into atomic-scale behaviour at its surface. Based on ab-initio thermodynamics, we constructed a phase diagram mapping MgSc₂Se₄ surface stability as a function of the chemical potentials of its atomic species.[2],[3] Our results reveal the relative stability of different surface terminations and planes. These findings provide fundamental insights into MgSc₂Se₄ surface properties essential for understanding and optimising solid-state magnesium battery performance.
[1] P. Canepa, S. Bo, G. Sai Gautam,B. Key, W. D. Richards,T. Shi, Y. Tian, Y. Wang, J. Li, G. Ceder, Nature Communications, 2017, 8, 1.
[2] K. Reuter, M. Scheffler, Physical Review B, 2001, 65, 035406.
[3] A. Groß, Curr. Opin. Electrochem., 2021, 27, 100684.
[4] K. Momma, F. Izumi, J. Appl. Crystallogr., 2011, 44, 1272-1276.
