The\nEffects of Nanoconfinement\nin LiBH<sub>4</sub>·1/2CH<sub>3</sub>NH<sub>2</sub>–Al<sub>2</sub>O<sub>3</sub> Composites

Optimization of all-solid-state lithium\nbatteries necessitates\nthe development of fast Li-ion conducting electrolytes. Lithium borohydride-based\nmaterials are a promising class of Li<sup>+</sup> conductors with\nhigh ionic conductivity at ambient conditions. Here, we report the\neffects of nanoconfinement of LiBH<sub>4</sub>·1/2CH<sub>3</sub>NH<sub>2</sub> with Al<sub>2</sub>O<sub>3</sub> nanoparticles, which\nresult in the stabilization of an amorphous phase of LiBH<sub>4</sub>·1/2CH<sub>3</sub>NH<sub>2</sub>. Consequently, the nanocomposites\nshow an altered activation energy and demonstrate an order of magnitude\nincrease in conductivity, reaching an extremely high ionic conductivity\nof σ(Li<sup>+</sup>) = 1.6 × 10<sup>–2</sup> S/cm\nat 34 °C. Thus, this work demonstrates that nanocomposite formation\nis an effective strategy to stabilize amorphous states to achieve\nhigher ionic conductivity and at the same time provide a more stable\nmechanical framework.