Effect of oxygen addition on phase composition and activation properties of TiFe alloy

• Published in: International journal of hydrogen energy 2023-03, Vol.48 (23), p.8563-8572
• Main Authors: Liu, Huang, Zhang, Jingxi, Sun, Pei, Zhou, Chengshang, Liu, Yong, Fang, Zhigang Zak
• Format: Article
• Language: English
• Subjects: Hydrogen storage; Metal hydrides; Oxygen addition; TiFe alloy
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2022.11.353

TiFe is one of the most promising hydrogen storage materials owing to its high volumetric hydrogen capacity, moderate operating temperature, and low cost. Oxygen is an inevitable impurity that affects the hydrogen storage properties of TiFe alloys. In this paper, the effect of oxygen addition on the phase composition and hydrogen storage properties of TiFe alloys is systematically investigated. We found that a high oxygen addition improves the initial hydrogen sorption of TiFe. The TiFe-O3.78 alloy achieves full activation after two ab/desorption cycles at room temperature. The high oxygen content facilitates the formation of Ti4Fe2O oxide in TiFe alloy, leading to improved activation kinetics. Moreover, due to the oxygen addition, the amount of TiFe primary phase reduces, and the corresponding hydrogen capacity degrades. Increasing oxygen content also leads to a slight increase in the hydrogenation equilibrium pressure, but almost no impact on the thermodynamics of TiFe alloy. •Oxygen addition decreased the TiFe phase fraction and reduced hydrogen storage capacity.•High oxygen content addition facilitates room temperature activation of TiFe alloy.•The TiFe-O3.78 alloy can be easily fully activated within 2 hydrogen cycles at room temperature.•Oxygen addition resulted in a slight increase in equilibrium pressures of TiFe-alloys.