Ionic Transport in Potential Coating Materials for Mg Batteries

Abstract

A major bottleneck for the development of Mg batteries is the identification of liquid electrolytes that are simultaneously compatible with the Mg-metal anode and high-voltage cathodes. One strategy to widen the stability windows of current non-aqueous electrolytes is to introduce protective coating materials at the electrodes, where coating materials are required to exhibit swift Mg transport. In this work, we use a combination of first-principles calculations and ion-transport theory to evaluate the migration barriers for nearly 27 Mg-containing binary, ternary, and quaternary compounds spanning a wide chemical space. Combining mobility, electronic band gaps, and stability requirements, we identify MgSiN${}_2$, MgI${}_2$, MgBr${}_2$, MgSe, and MgS as potential coating materials against the highly reductive Mg metal anode, and we find MgAl${}_2$O${}_4$ and Mg(PO${}_3$)${}_2$ to be promising materials against high-voltage oxide cathodes (up to $\sim$3~V).

arXiv comment32 pages and4 figures

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