Preparation and Properties of Ball-Milled MgH₂/Al Nanocomposites for Hydrogen Storage

Abstract

For reversible hydrogen storage properties of 17MgH₂ + 12Al ↔ Mg₁₇Al₁₂ + 17H₂, MgH₂/Al nanocomposites (I)–(IV) synthesized by ball milling of MgH₂ and Al (or AlH₃) were studied in connection with milling conditions. The milling processes consisting of two steps were effective to improve the hydrogen storage behavior; MgH₂ was first milled with solutions of triethylaluminium (TEA) in hexane, followed by addition of Al and TEA solutions. The mixtures were further milled to yield the nanocomposite (III). In preparing the nanocomposite (IV), AlH₃ was used instead of Al. For the nanocomposites (III) and (IV), it was proved by XRD, TDS, DSC and PCI that such ball-milling led to high dispersion of nanocrystalline MgH₂ in Al and/or AlH₃ matrix in the resulting nanocomposites. In DSC measured under a 0.1 MPa hydrogen atmosphere, the nanocomposites (III) and (IV) exhibited reversible H₂ absorption and desorption at 493–503 and 573–593 K, respectively.