Realization of Mg intercalation in a thermodynamically stable layer-structured oxide.

Magnesium batteries have emerged as one of the considerable choices for next-generation batteries. Oxide compounds have attracted great attention as cathodes for magnesium batteries because of their high output voltages and ease of synthesis. However, a majority of the reported results are based on metastable nanoscale oxide materials. This study puts forward a thermodynamically stable layer-structured oxide KMnO with an enlarged lattice spacing as a model cathode material employing optimized electrolytes, enabling Mg intercalation into the KMnO framework in a real magnesium battery directly using Mg foil as the anode. First-principles calculations implied that the enlarged layer spacing could decrease the migration energy barrier of Mg in the layered oxide. This work can pave the way to understanding the fundamental intercalation behavior of Mg in magnesium batteries.