Evaluation of Mg compounds as coating materials in Mg batteries

TL;DR

This study uses first-principles calculations to identify promising Mg compounds as protective coatings for Mg batteries, aiming to improve electrolyte stability and battery performance.

Contribution

It systematically maps electrochemical stability windows of Mg compounds, revealing new potential coating materials for Mg battery anodes and cathodes.

Findings

Mg-halides and Mg(BH$_4$)$_2$ are promising anode coatings.

MgF$_2$, Mg(PO$_3$)$_2$, and MgP$_4$O$_11$ are effective cathode passivators.

Identified materials could enhance electrolyte compatibility and battery stability.

Abstract

Mg batteries utilizing a Mg metal anode with a high-voltage intercalation cathode define a potential pathway toward energy storage with high energy density. However, the realization of Mg batteries is plagued by the instability of existing electrolytes against the Mg-metal anode and high-voltage cathode materials. One viable solution to this problem is the identification of protective coating materials that could effectively separate the distinct chemistries of the metal-anode and the cathode materials from the electrolyte. Using first-principles calculations we map the electrochemical stability windows for non-redox-active Mg binary and ternary compounds in order to identify potential coating materials for Mg batteries. Our results identify Mg-halides and Mg(BH$_4$)$_2$ as promising anode coating materials based on their significant reductive stability. On the cathode side, we single out MgF$_2$, Mg(PO$_3$)$_2$ and MgP$_4$O$_11$ as effective passivating agents.