通过添加钇改善镁基合金的氢吸收和解吸动力学,Journal of Power Sources

选择钇（Y）可以改变镁（Mg）的微观结构，从而改善储氢性能。因此，标称成分为Mg 24 Y x（x = 1–5）通过廉价的铸造技术制造。通过X射线衍射，扫描电子显微镜和高分辨率透射电子显微镜分析，对它们在氢化和脱水过程中的微观结构和相变进行了表征。等温氢的吸收和解吸动力学也通过Sievert's型装置在各种温度下测量。可以清楚地观察到二元合金的典型多相结构。所有这些合金在适当的温度下均可可逆地吸收和解吸大量的氢。Y的添加显着促进了氢吸收动力学。但是，这导致可逆储氢能力的降低。随着Y含量的增加，观察到脱氢速率的最大值。镁24Y 3合金具有最佳的解吸动力学性能，并且可以在12分钟内在380°C下解吸约5.4 wt％的氢。结合Johnson-Mehl-Avrami动力学模型和Arrhenius方程，评估了合金的脱氢活化能。Mg 24 Y 3合金也具有最低的脱氢活化能（119kJ mol -1）。

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Improved hydrogen absorption and desorption kinetics of magnesium-based alloy via addition of yttrium

Yttrium (Y) is selected to modify the microstructure of magnesium (Mg) to improve the hydrogen storage performance. Thereby, binary alloys with the nominal compositions of Mg24Yx (x = 1–5) are fabricated by inexpensive casting technique. Their microstructure and phase transformation during hydriding and dehydriding process are characterized by using X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy analysis. The isothermal hydrogen absorption and desorption kinetics are also measured by a Sievert's-type apparatus at various temperatures. Typical multiphase structures of binary alloy can be clearly observed. All of these alloys can reversibly absorb and desorb large amount of hydrogen at proper temperatures. The addition of Y markedly promotes the hydrogen absorption kinetics. However, it results in a reduction of reversible hydrogen storage capacity. A maximum value of dehydrogenation rate is observed with the increase of Y content. The Mg24Y3 alloy has the optimal desorption kinetic performance, and it can desorb about 5.4 wt% of hydrogen at 380 °C within 12 min. Combining Johnson–Mehl–Avrami kinetic model and Arrhenius equation, the dehydrogenation activation energy of the alloys are evaluated. The Mg24Y3 alloy also has the lowest dehydrogenation activation energy (119 kJ mol−1).