The Effects of Nanoconfinement in LiBH₄·1/2CH₃NH₂–Al₂O₃ Composites

Optimization of all-solid-state lithium batteries necessitates the development of fast Li-ion conducting electrolytes. Lithium borohydride-based materials are a promising class of Li+ conductors with high ionic conductivity at ambient conditions. Here, we report the effects of nanoconfinement of LiBH4·1/2CH3NH2 with Al2O3 nanoparticles, which result in the stabilization of an amorphous phase of LiBH4·1/2CH3NH2. Consequently, the nanocomposites show an altered activation energy and demonstrate an order of magnitude increase in conductivity, reaching an extremely high ionic conductivity of σ(Li+) = 1.6 × 10–2 S/cm at 34 °C. Thus, this work demonstrates that nanocomposite formation is an effective strategy to stabilize amorphous states to achieve higher ionic conductivity and at the same time provide a more stable mechanical framework.