Fast Room-Temperature Mg-Ion Conduction in Clay-Like Halide Glassy Electrolytes

XC Yang and S Gupta and Y Chen and D Sari and HM Hau and ZJ Cai and C Dun and M Qi and L Ma and Y Liu and JJ Urban and G Ceder, ADVANCED ENERGY MATERIALS, 14 (2024).

DOI: 10.1002/aenm.202400163

The discovery of mechanically soft solid-state materials with fast Mg- ion conduction is crucial for the development of solid-state magnesium batteries. In this paper, novel magnesium gallium halide compounds are reported that achieve high ionic conductivity of 0.47 mS cm-1 at room temperature. These Mg-ion conductors obtained by ball milling Mg and Ga salts exhibit clay-like mechanical properties, enabling intimate contact at the electrode-electrolyte interface during battery cycling. With a combination of experimental and computational analysis, this study identifies that the soft-clay formation is induced by partial anion exchange during milling. This partial anion exchange creates undercoordinated magnesium ions in a chlorine-rich environment, yielding fast Mg-ion conduction. This work demonstrates the potential of clay- like halide electrolytes for all-solid-state magnesium batteries, with possible further extension to other multivalent battery systems. The authors report novel clay-like magnesium gallium halide compounds that achieve high ionic conductivity of 0.47 mS cm-1 at room temperature. Combined experimental and computational analyses reveal that partial anion exchange during high-energy ball milling leads to both soft-clay formation and high ionic conductivity. image

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