Simultaneous desorption behavior of M borohydrides and Mg2FeH6 reactive hydride composites (M = Mg, then Li, Na, K, Ca)

• Published in: Applied physics letters 2015-08, Vol.107 (7)
• Main Authors: Chaudhary, Anna-Lisa, Li, Guanqiao, Matsuo, Motoaki, Orimo, Shin-ichi, Deledda, Stefano, Sørby, Magnus H., Hauback, Bjørn C., Pistidda, Claudio, Klassen, Thomas, Dornheim, Martin
• Format: Article
• Language: English
• Subjects: Applied physics; Ball milling; Borohydrides; Calcium; Coordination compounds; Desorption; Hydrides; Hydrogen storage; Magnesium; Mass spectrometry; Sodium; Transition metal compounds
• ISSN: 0003-6951; 1077-3118
• DOI: 10.1063/1.4929340

Combinations of complex metal borohydrides ball milled with the transition metal complex hydride, Mg2FeH6, are analysed and compared. Initially, the Reactive Hydride Composite (RHC) of Mg2+ cation mixtures of Mg2FeH6 and γ-Mg(BH4)2 is combined in a range of molar ratios and heated to a maximum of 450 °C. For the molar ratio of 6 Mg2FeH6 + Mg(BH4)2, simultaneous desorption of the two hydrides occurred, which resulted in a single event of hydrogen release. This single step desorption occurred at temperatures between those of Mg2FeH6 and γ-Mg(BH4)2. Keeping this anionic ratio constant, the desorption behavior of four other borohydrides, Li-, Na-, K-, and Ca-borohydrides was studied by using materials ball milled with Mg2FeH6 applying the same milling parameters. The mixtures containing Mg-, Li-, and Ca-borohydrides also released hydrogen in a single event. The Mass Spectrometry (MS) results show a double step reaction within a narrow temperature range for both the Na- and K-borohydride mixtures. This phenomenon, observed for the RHC systems at the same anionic ratio with all five light metal borohydride mixtures, can be described as simultaneous hydrogen desorption within a narrow temperature range centered around 300 °C.