On the long-term cyclic stability of near-eutectic Mg-Mg2Ni alloys

Authors
Fadonougbo, Julien O.Kim, Han-JinSuh, Byeong-ChanYim, Chang DongNa, Tae-WookPark, Hyung-KiSuh, Jin-Yoo
Issue Date
2022-01
Publisher
Pergamon Press Ltd.
Citation
International Journal of Hydrogen Energy, v.47, no.6, pp.3939 - 3947
Abstract
In this investigation, we report the cyclic performance, microstructure and thermal properties of near eutectic Mg-Ni alloys with different Ni contents (4.4, 11.3 and 16.3 at%). The starting cast ingots are mechanically chipped to flakes of about 400 mm, all displaying composite structures characterized by a typical eutectic microstructure with rather coarse features (1-5 mm). The flakes are cycled 1000 times at 330 degrees C under 30/1 bar H2 for the absorption/desorption processes. The hydrogen storage capacity is maintained throughout the cycling: 5.09, 4.46 and 3.49 wt% H2 for Ni16.3, Ni11.3 and Ni4.4 (at%), respectively. No significant microstructural change is observed, indicating the excellent stability of the alloys at elevated temperatures. Nevertheless, a marked porosity, and spheroidal Mg2Ni clusters can be noted after cycling, however their exact contribution to reaction kinetics has yet to be fully elucidated. An attempt is made to estimate the dehydrogenation activation energy of Ni16.3, and the calculated value seems comparable to that obtained for an early cycling stage (10 cycles). In the light of the superior stability under cyclic service and the low decomposition temperature, the Mg-Mg2Ni system is shown to possess an excellent potential for long-term hydrogen and heat storage applications.
Keywords
HYDROGEN STORAGE PROPERTIES; HYDRIDING PROPERTIES; SORPTION KINETICS; METAL-HYDRIDES; MG; MAGNESIUM; NI; MG2NIH4; DESORPTION; MICROSTRUCTURE; Metal hydrides; Hydrogen solid-state storage; Mg-Ni eutectic alloys; Cyclic performance
ISSN
0360-3199
URI
https://pubs.kist.re.kr/handle/201004/76812
DOI
10.1016/j.ijhydene.2021.11.025
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KIST Article > 2022
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