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<p>AB<sub>2</sub>-type hydrogen storage alloys are promising due to their low cost, rapid hydrogen ab/desorption, and good cycling stability, but their narrow operating temperature range and poor plateau performance limit practical applications. In this work, Ti<sub>0.75</sub>Zr<sub>0.3-<i>x</i></sub>Cr<sub>0.75</sub>Mn<sub>1.25</sub>Nb<sub><i>x</i></sub> alloys were synthesized, with partial Zr substitution by Nb, to develop a wide-temperature-range hydrogen storage alloy. The optimized alloy Ti<sub>0.75</sub>Zr<sub>0.22</sub>Cr<sub>0.75</sub>Mn<sub>1.25</sub>Nb<sub>0.08</sub> exhibited an increase in effective hydrogen desorption capacity from 1.64 wt% to 1.77&#xa0;wt% at 25&#xa0;°C. Similarly, the alloy Ti<sub>0.75</sub>Zr<sub>0.20</sub>Cr<sub>0.75</sub>Mn<sub>1.25</sub>Nb<sub>0.10</sub> maintained an effective hydrogen desorption capacity of 1.71&#xa0;wt% at − 20&#xa0;°C, demonstrating its performance across different operating conditions. Nb substitution enhanced hydrogen desorption by reducing hysteresis, increasing plateau pressure, and optimizing cycling stability (95.49% capacity retention after 200 cycles). DFT calculations revealed that hydrogen atoms preferentially occupy A2B2 interstitial sites, whereas Nb atoms substitute at A-site positions, forming weaker Nb-H bonds that reduce hydride stability and improve desorption performance. This work demonstrates that Nb substitution effectively optimizes AB<sub>2</sub>-type alloys and supports the development of wide-temperature-range hydrogen storage materials.</p> Graphical abstract <p></p>

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Atomic occupation of Nb in AB2-type alloy and its effect on hydrogen storage property

  • 期刊论文

  • 发表日期：

    2025年10月31日

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  • Chaojie Li,
  • Huazhou Hu,
  • Chenhu Xu,
  • Houqun Xiao,
  • Luocai Yi,
  • Chuanming Ma,
  • Lei Liu,
  • Qingjun Chen

摘要

AB2-type hydrogen storage alloys are promising due to their low cost, rapid hydrogen ab/desorption, and good cycling stability, but their narrow operating temperature range and poor plateau performance limit practical applications. In this work, Ti0.75Zr0.3-xCr0.75Mn1.25Nbx alloys were synthesized, with partial Zr substitution by Nb, to develop a wide-temperature-range hydrogen storage alloy. The optimized alloy Ti0.75Zr0.22Cr0.75Mn1.25Nb0.08 exhibited an increase in effective hydrogen desorption capacity from 1.64 wt% to 1.77 wt% at 25 °C. Similarly, the alloy Ti0.75Zr0.20Cr0.75Mn1.25Nb0.10 maintained an effective hydrogen desorption capacity of 1.71 wt% at − 20 °C, demonstrating its performance across different operating conditions. Nb substitution enhanced hydrogen desorption by reducing hysteresis, increasing plateau pressure, and optimizing cycling stability (95.49% capacity retention after 200 cycles). DFT calculations revealed that hydrogen atoms preferentially occupy A2B2 interstitial sites, whereas Nb atoms substitute at A-site positions, forming weaker Nb-H bonds that reduce hydride stability and improve desorption performance. This work demonstrates that Nb substitution effectively optimizes AB2-type alloys and supports the development of wide-temperature-range hydrogen storage materials.

Graphical abstract