Effect of the particle size evolution on the hydrogen storage performance of KH doped Mg(NH₂)₂ + 2LiH
Publication date
2022-03-04
Document type
Forschungsartikel
Author
Gizer, Gökhan
Karimi, Fahim
Pistidda, Claudio
Cao, Hujun
Shang, Yuanyuan
Gericke, Eike
Hoell, Armin
Pranzas, P. Klaus
Dornheim, Martin
Organisational unit
Scopus ID
Publisher
Springer
Series or journal
Journal of Materials Science
ISSN
Periodical volume
57
Periodical issue
22
First page
10028
Last page
10038
Peer-reviewed
✅
Part of the university bibliography
✅
Language
English
Abstract
In recent years, many solid-state hydride-based materials have been considered as hydrogen storage systems for mobile and stationary applications. Due to a gravimetric hydrogen capacity of 5.6 wt% and a dehydrogenation enthalpy of 38.9 kJ/mol H₂, Mg(NH₂)₂ + 2LiH is considered a potential hydrogen storage material for solid-state storage systems to be coupled with PEM fuel cell devices. One of the main challenges is the reduction of dehydrogenation temperature since this system requires high dehydrogenation temperatures (~ 200 °C). The addition of KH to this system significantly decreases the dehydrogenation onset temperature to 130 °C. On the one hand, the addition of KH stabilizes the hydrogen storage capacity. On the other hand, the capacity is reduced by 50% (from 4.1 to 2%) after the first 25 cycles. In this work, the particle sizes of the overall hydride matrix and the potassium-containing species are investigated during hydrogen cycling. Relation between particle size evolution of the additive and hydrogen storage kinetics is described by using an advanced synchrotron-based technique: Anomalous small-angle X-ray scattering, which was applied for the first time at the potassium K-edge for amide-hydride hydrogen storage systems. The outcomes from this investigation show that, the nanometric potassium-containing phases might be located at the reaction interfaces, limiting the particle coarsening. Average diameters of potassium-containing nanoparticles double after 25 cycles (from 10 to 20 nm). Therefore, reaction kinetics at subsequent cycles degrade. The deterioration of the reaction kinetics can be minimized by selecting lower absorption temperatures, which mitigates the particle size growth, resulting in two times faster reaction kinetics.
Description
This article is licensed under a Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/).
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Published version
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Open Access Funding
Springer Nature (DEAL)