期刊
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
卷 38, 期 3, 页码 1460-1468出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.ijhydene.2012.11.006
关键词
Hydrogen storage; Magnesium alanate; High-energy ball milling; Thermodynamics; Kinetics
资金
- National Natural Science Foundation for Excellent Youth Scholars of China [51222101]
- National Natural Science Foundation of China [51171170]
- National Natural Science Foundation for Distinguished Young Scholars of China [51025102]
- Ministry of Science and Technology of China [2010CB631304]
- Science and Technology Department of Zhejiang Province [2011R10017, 2010R50013]
The decreased dehydrogenation temperature and improved dehydrogenation kinetics were achieved by high-energy ball milling Mg(AlH4)(2). The particle size, grain size, microstrain and lattice distortion of the post-milled samples, i.e., from macro- to micro-scale, were systematically characterized by means of SEM and XRD measurements. The results indicated that the high-energy ball milling process led to not only a decrease in the particle size and grain size but also an increase in the microstrain and lattice distortion, which provides a synergetic effect of the thermodynamics and kinetics on lowering the dehydrogenation temperatures of the post-milled Mg(AlH4)(2) samples. Prom the kinetic point of view, the refinement of the particles and grains shortens the diffusion distance, and the increase of the microstrain and lattice distortion enhances the diffusivity, which work together to decrease the apparent activation energy for hydrogen desorption. Besides, the presence of microstrain and lattice distortion increased the free energy of the post-milled samples, which was released by recovery and recrystallization processes upon heating. This offers more heat release during the first-step dehydrogenation, consequently leading to thermodynamically decline in dehydrogenation temperatures of the post-milled samples. Such a finding provides insights into the mechanistic understanding on decreased dehydrogenation temperature and improved dehydrogenation kinetics of the post-milled metal hydrides as hydrogen storage materials. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.
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