Hydrogen-Induced Reversible Phase Transformations and Hydrogen Storage Properties of Mg–Ag–Al Ternary Alloys

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• 作者：Yanshan Lu ; Hui Wang ; Jiangwen Liu ; Ziming Li ; Liuzhang Ouyang ; Min Zhu
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：December 8, 2016
• 年：2016
• 卷：120
• 期：48
• 页码：27117-27127
• 全文大小：774K
• ISSN：1932-7455

文摘

Overly stable thermodynamics and sluggish kinetics hinder the practical applications of Mg-based hydrogen storage alloys. Compositional and structural modifications are important strategies in tuning these hydrogen storage properties. In this study, Mg-based Mg–Ag–Al ternary alloys were investigated to explore their performance as hydrogen storage alloys. Mg₈₀Ag₁₅Al₅ exhibits a reaction pathway that differs from that in pure Mg, in which the intermediate phase, consisting of a new ternary solid solution MgAg(Al), reacts with MgH₂ during dehydriding and contributes to an increase in the dehydriding equilibrium pressure (0.22 MPa at 300 °C) and to a reversible hydrogen storage capacity of 1.7 wt %. Adjusting the composition to Mg₈₅Ag₅Al₁₀ results in a reversible hydrogen storage capacity of approximately 3.8 wt % and an elevated equilibrium pressure (0.26 MPa at 300 °C). These Mg–Ag–Al ternary alloys also show enhanced hydrogen sorption kinetics relative to that of Mg, and the apparent activation energies for hydrogenation and dehydrogenation of the Mg₈₅Ag₅Al₁₀ sample are lowered to 74.5 kJ mol^–1 and 124.8 kJ mol^–1, respectively. This work demonstrates the possibility of exploring new hydrogen storage alloys via creating different reaction pathways for hydrogen-induced reversible phase transformations.