Nanostructured, complex hydride systems for hydrogen generation

• Main Authors: Robert A. Varin, Amirreza Shirani Bidabadi
• Format: Article
• Language: English
• Published: AIMS Press 2015-02-01
• Series: AIMS Energy
• Subjects: hydrogen generation; mechano-chemical activation synthesis; mechanical dehydrogenation; thermal dehydrogenation
• Online Access: http://www.aimspress.com/energy/article/35/fulltext.html

Complex hydride systems for hydrogen (H₂) generation for supplying fuel cells are being reviewed. In the first group, the hydride systems that are capable of generating H₂ through a mechanical dehydrogenation phenomenon at the ambient temperature are discussed. There are few quite diverse systems in this group such as lithium alanate (LiAlH₄) with the following additives: nanoiron (n-Fe), lithium amide (LiNH₂) (a hydride/hydride system) and manganese chloride MnCl₂ (a hydride/halide system). Another hydride/hydride system consists of lithium amide (LiNH₂) and magnesium hydride (MgH₂), and finally, there is a LiBH₄-FeCl₂ (hydride/halide) system. These hydride systems are capable of releasing from ~4 to 7 wt.% H₂at the ambient temperature during a reasonably short duration of ball milling. The second group encompasses systems that generate H₂ at slightly elevated temperature (up to 100 °C). In this group lithium alanate (LiAlH₄) ball milled with the nano-Fe and nano-TiN/TiC/ZrC additives is a prominent system that can relatively quickly generate up to 7 wt.% H₂ at 100 °C. The other hydride is manganese borohydride (Mn(BH₄)₂) obtained by mechano-chemical activation synthesis (MCAS). In a ball milled (2LiBH₄ + MnCl₂) nanocomposite, Mn(BH₄)₂co-existing with LiCl can desorb ~4.5 wt.% H₂ at 100 °C within a reasonable duration of dehydrogenation. Practical application aspects of hydride systems for H₂generation/storage are also briefly discussed.