Description:
<jats:title>Abstract</jats:title><jats:p>Solid-state magnesium ion conductors with exceptionally high ionic conductivity at low temperatures, 5 × 10<jats:sup>−8</jats:sup> Scm<jats:sup>−1</jats:sup> at 30 °C and 6 × 10<jats:sup>−5</jats:sup> Scm<jats:sup>−1</jats:sup> at 70 °C, are prepared by mechanochemical reaction of magnesium borohydride and ethylenediamine. The coordination complexes are crystalline, support cycling in a potential window of 1.2 V, and allow magnesium plating/stripping. While the electrochemical stability, limited by the ethylenediamine ligand, must be improved to reach competitive energy densities, our results demonstrate that partially chelated Mg<jats:sup>2+</jats:sup> complexes represent a promising platform for the development of an all-solid-state magnesium battery.</jats:p>