Highly improved hydrogen storage dynamics of nanocrystalline and amorphous NdMg 12 -type alloys by mechanical milling
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ORIGINAL PAPER
Highly improved hydrogen storage dynamics of nanocrystalline and amorphous NdMg12‑type alloys by mechanical milling Ying‑chun Liu1 · Yan Qi2 · Wei Zhang2 · Jin‑liang Gao3 · Yang‑huan Zhang2 Received: 7 April 2020 / Revised: 5 June 2020 / Accepted: 9 June 2020 © China Iron and Steel Research Institute Group 2020
Abstract To improve the hydrogenation and dehydrogenation dynamics of NdMg12-type alloy, we replaced part of Mg with Ni in the samples and used the ball milling method to prepare N dMg11Ni + x wt.% Ni (x = 100, 200) samples. The influences of milling duration and Ni content on the electrochemical and gaseous dynamics of the samples were studied in detail. Dehydrogenation activation energies of samples were calculated by using Kissinger and Arrhenius methods. The conclusions show that the dynamic properties of samples are significantly enhanced with the increase in Ni content. With the change of the milling duration, the gaseous hydrogenation rate and high rate discharging capability reach the maximal values. However, the dehydrogenation dynamics of sample alloys are always enhanced with the prolonging of milling duration. More concretely, prolonging milling duration from 5 to 60 h improves the dehydrogenation ratio of N dMg11Ni + 100 wt.% Ni alloy from 58.03% to 64.81% and that of N dMg11Ni + 200 wt.% Ni alloy from 62.20% to 71.59%. Besides, the enhancement of gaseous hydrogen storage dynamics of the samples is believed to be the result of the declined dehydrogenation activation energy resulted from the increase in milling duration and Ni content. Keywords NdMg12 alloy · Hydrogen storage dynamics · Activation energy · Mechanical milling · Ni addition
1 Introduction An official survey released by China Ministry of Environmental Protection stated that vehicle exhaust is the mainspring for the serious haze in Beijing. With the continuous growth of car ownership, the problems of fossil energy and environmental pollution have become increasingly prominent. In fact, the energy consumption in the transportation sector is very large, accounting for about one-quarter of the total expenditure of energy [1]. Those problems are getting more and more serious, forcing researchers to look for new alternative clean energy resources. Hydrogen energy is deemed as a promising option due to inexhaustible use, zero greenhouse gas emissions and high energy density [2–4]. * Yang‑huan Zhang [email protected] 1
China National Institute of Standardization, Beijing 100191, China
2
Department of Functional Material Research, Central Iron and Steel Research Institute, Beijing 100081, China
3
Weishan Cisri Rare Earth Materials Co., Ltd., Jining 277600, Shandong, China
One of the crux technical barriers to achieve hydrogenfueled vehicles or cells on-board fuel is how to develop an actual hydrogen storage system [5]. Researchers have investigated many kinds of materials to store hydrogen, including complex hydrides, adsorbent materials, metallic hydrides and chemical hydrides [6–9]. Metal hydride
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