Magnesium batteries have gained attention due to their potential advantages over lithium-ion batteries, including high energy densities, high safety, low cost, and abundance in the earth’s crust. However, the practical application of Mg2+-based energy devices has been hindered by the poor conductivity of magnesium ions in solids at room temperature.
To overcome the hurdle of poor solid-state conductivity, the research team utilized a MOF known as MIL-101 as the main framework and encapsulated Mg2+ ions in its nanopores. In the resultant MOF-based electrolyte, Mg2+ was loosely packed, allowing the migration of divalent Mg2+ ions. Exposing the electrolyte to acetonitrile vapors further enhanced ion conductivity, resulting in a superionic conductivity of 1.9 × 10−3 S cm−1. This conductivity is the highest ever reported for a crystalline solid containing Mg2+, indicating significant potential for practical applications in magnesium batteries.