Comparative investigation on the hydrogenation/dehydrogenation characteristics and hydrogen storage properties of Mg3Ag and Mg3Y |
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| Authors: | LZ Ouyang ZJ Cao L Yao H Wang JW Liu M Zhu |
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| Affiliation: | 1. School of Materials Science and Engineering, South China University of Technology, Guangzhou 510641, People''s Republic of China;2. Key Laboratory of Advanced Energy Storage Materials of Guangdong Province, South China University of Technology, Guangzhou 510641, People''s Republic of China;3. The Key Laboratory of Fuel Cell Technology of Guangdong Province, South China University of Technology, Guangzhou 510641, People''s Republic of China |
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| Abstract: | The hydrogenation/dehydrogenation characteristics and hydrogen storage properties of nominal Mg3Ag and Mg3Y alloys prepared by induction melting were investigated. The as-melted Mg3Ag alloy was composed of Mg54Ag17 phase, while Mg3Y consisted of Mg24Y5 and Mg2Y phases. Mg54Ag17 transformed into MgAg and MgH2 during the first hydrogenation, and the phase transition of the following hy/dehydrogenation cycles was Mg3Ag + 2H2 ↔ MgAg + 2MgH2. Both Mg24Y5 and Mg2Y undertook disproportion reactions and decomposed into MgH2 and YH3. Experimental and calculated results demonstrated that there was no necessary relation between the thermodynamic stabilities and the size interstices in these alloys. The dehydrogenation enthalpy change (ΔH) and entropy change (ΔS) of Mg3Ag were calculated and compared with that of pure Mg, which indicated that the increase of ΔS could counteract the stabilization effect of ΔH, which offered a method for tuning the thermodynamic properties of Mg-based alloys. |
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| Keywords: | Hydrogen storage Magnesium alloys Induction melting Thermodynamics |
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