Magnesium hydride (MgH2) is a candidate material for hydrogen storage. MgH2–AlH3 composite shows superior hydrogen desorption properties than pure MgH2. However, this composite still suffers from poor cycling performance. In this work, NbF5 was utilized to improve the cycling properties of the MgH2–AlH3 composite. Cycling hydrogen desorption studies show that NbF5 significantly improves the cycling stability of MgH2–AlH3. The MgH2–AlH3–NbF5 composite can release about 2.7 wt% of hydrogen at 300 °C for 1 h and the hydrogen desorption capacity can maintain at 2.7 wt% for more than 100 cycles. In comparison, the hydrogen desorption capacity of the MgH2–AlH3 composite is decreasing with the cycle number increasing. The capacity is reduced from a maximum value of 3.3 wt% to about 1.0 wt% after 40 cycles. Brunauer–Emmett–Teller (BET) surface area measurements show that the particle size of MgH2–AlH3 composite decreases after cycling, which means pulverization of the composite. NbF5 can to some extent suppress the pulverization of the composite during cycling, which partially contributes to the improvement of the cycling hydrogen desorption properties of the material. NbF5 addition significantly improves the cycling hydrogen desorption properties of the MgH2−AlH3 composite.

中文翻译：

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MgH2-AlH3-NbF5储氢材料的循环氢解吸性能和微观结构

氢化镁 (MgH2) 是储氢的候选材料。MgH2-AlH3 复合材料显示出比纯 MgH2 更好的氢解吸性能。然而，这种复合材料的循环性能仍然很差。在这项工作中，NbF5 被用来改善 MgH2-AlH3 复合材料的循环性能。循环氢解吸研究表明，NbF5 显着提高了 MgH2-AlH3 的循环稳定性。MgH2–AlH3–NbF5 复合材料在 300 °C 下 1 小时可释放约 2.7 wt% 的氢气，并且在 100 多个循环后，氢气解吸能力可保持在 2.7 wt%。相比之下，MgH2-AlH3 复合材料的氢解吸能力随着循环次数的增加而降低。在 40 次循环后，容量从最大值 3.3 wt% 降低到约 1.0 wt%。Brunauer-Emmett-Teller (BET) 表面积测量表明，MgH2-AlH3 复合材料的粒径在循环后减小，这意味着复合材料的粉化。NbF5 可以在一定程度上抑制循环过程中复合材料的粉化，这在一定程度上有助于提高材料的循环氢解吸性能。NbF5 添加显着改善了 MgH2-AlH3 复合材料的循环氢解吸性能。