Ca(BH4)(2)-MgF2 Reversible Hydrogen Storage: Reaction Mechanisms and Kinetic Properties

Summary, in English

A composite of Ca(BH4)(2)-MgF2 is proposed as a reversible hydrogen storage system. The dehydrogenation and rehydrogenation reaction mechanisms are investigated by in situ time-resolved synchrotron radiation powder X-ray diffraction (SR-PXD) and Raman spectroscopy. The formation of an intermediate phase (CaF2-xHx) is observed during rehydrogenation. The hydrogen content of 4.3 wt % is obtained within 4 h during the first dehydrogenation at isothermal and isobaric conditions of 330 degrees C and 0.5 bar H-2, respectively. The cycling efficiency is evaluated by three release and uptake cycles together with absorbed hydrogen content in the range 5.1-5.8 wt % after 2.5 h (T = 330 degrees C and p(H-2) = 130 bar). The kinetic properties on the basis of hydrogen absorption are comparable for all cycles. As compared to pure Ca(BH4)(2) and Ca(BH4)(2)-MgH2 composite, Ca(BH4)(2)-MgF2 composite reveals the kinetic destabilization and the reproducibility of hydrogen storage capacities during cycling, respectively.

• Author: Rapee Gosalawit-Utke; Karina Suarez; Jose M. Bellosta von Colbe; Ulrike Boesenberg; Torben R. Jensen; Yngve Cerenius; Christian Bonatto Minella; Claudio Pistidda; Gagik Barkhordarian; Matthias Schulze; Thomas Klassen; Ruediger Bormann; Martin Dornheim
• Department/s: MAX IV Laboratory
• Publishing year: 2011
• Language: English
• Pages: 3762-3768
• Publication/Series: Journal of Physical Chemistry C
• Volume: 115
• Issue: 9
• Links: http://dx.doi.org/10.1021/jp108236e
• Document type: Journal article
• Publisher: The American Chemical Society (ACS)
• Topic: Natural Sciences; Physical Sciences
• Status: Published
• ISBN/ISSN/Other: ISSN: 1932-7447