Effective nanoconfinement of 2LiBH4-MgH2 via simply MgH2 premilling for reversible hydrogen storages

Rapee Gosalawit Utke*, Sophida Thiangviriya, Payam Javadian, Daniel Laipple, Claudio Pistidda, Nils Bergemann, Christian Horstmann, Torben R. Jensen, Thomas Klassen, Martin Dornheim

*Corresponding author for this work

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaperJournal articleResearchpeer-review

Abstract

To improve nanoconfinement of LiBH4 and MgH2 in carbon aerogel scaffold (CAS), particle size reduction of MgH2 by premilling technique before melt infiltration is proposed. MgH2 is premilled for 5 h prior to milling with LiBH4 and nanoconfinement in CAS to obtained nanoconfined 2LiBH(4)-premilled MgH2. Significant confinement of both LiBH4 and MgH2 in CAS, confirmed by SEM-EDS mapping results, is achieved due to MgH2 premilling. Due to effective nanoconfinement, enhancement of CAS:hydride composite weight ratio to 1:1, resulting in increase of hydrogen storage capacity, is possible. Nanoconfined 2LiBH(4)-premilled MgH2 reveals a single-step dehydrogenation at 345 degrees C with no B2H6 release, while dehydrogenation of nanoconfined sample without MgH2 premilling performs in multiple steps at elevated temperatures (up to 430 degrees C) together with considerable amount of B2H6 release. Activation energy (E-A) for the main dehydrogenation of nanoconfined 2LiBH(4)-premilled MgH2 is considerably lower than those of LiBH4 and MgH2 of bulk 2LiBH(4)-MgH2 (Delta E-A = 31.9 and 55.8 kJ/mol with respect to LiBH4 and MgH2, respectively). Approximately twice faster dehydrogenation rate are accomplished after MgH2 premilling. Three hydrogen release (T = 320 degrees C, P(H-2) = 3-4 bar) and uptake (T = 320-325 degrees C, P(H-2) = 84 bar) cycles of nanoconfined 2LiBH(4)-premilled MgH2 reveal up to 4.96 wt. % H-2 (10 Wt. % H-2 with respect to hydride composite content), while the 1st desorption of nanoconfined sample without MgH2 premilling gives 4.30 wt. % of combined B2H6 and H-2 gases. It should be remarked that not only kinetic improvement and B2H6 suppression are obtained by MgH2 premilling, but also the lowest dehydrogenation temperature (T = 320 degrees C) among other modified 2LiBH(4)-MgH2 systems is acquired. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
Original languageEnglish
JournalInternational Journal of Hydrogen Energy
Volume39
Issue28
Pages (from-to)15614-15626
Number of pages13
ISSN0360-3199
DOIs
Publication statusPublished - Sept 2014

Keywords

  • B2H6 suppression
  • Kinetic improvement
  • low dehydrogenation temperature
  • Reduction of activation energy
  • Particle size reduction
  • CARBON AEROGEL SCAFFOLD
  • LIBH4
  • COMPOSITES
  • THERMODYNAMICS
  • KINETICS
  • PATHWAY
  • SYSTEM

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