Effects of NbF5 addition on the hydrogen storage properties of LiAlH4

Authors

Mohammad IsmailFollow
Yue Zhao, University of WollongongFollow
Xuebin YuFollow
S. X. Dou, University of WollongongFollow

RIS ID

31904

Publication Details

Yu, X., Ismail, M., Dou, S. Xue. Zhao, Y. (2010). Effects of NbF₅ addition on the hydrogen storage properties of LiAlH₄. International Journal of Hydrogen Energy, 35 (6), 2361-2367.

Abstract

We investigated the effects of NbF₅ addition by ball milling on the hydrogen storage properties of LiAlH₄. Pressure-composition-temperature (PCT) experiments showed that addition of 0.5 and 1 mol% NbF₅ in LiAlH₄ improves the onset desorption temperature and results in little decrease in hydrogen capacity, with approximately 7.0 wt% released by 188 °C. Isothermal dehydriding kinetics measurements indicated that the NbF₅-doped sample shows an average dehydrogenation rate 5–6 times faster than that of the as-received LiAlH₄ sample. In the x-ray diffraction results, there are distinct peaks of Al and LiH that appear after desorption. There is no peak of NbF₅ before or after desorption. Desorption kinetics measurements indicated that the activation energy, E_A, for LiAlH₄ + 1 mol% NbF₅ is about 67 kJ/mol for first reaction stage and about 77 kJ/mol for second reaction stage. The desorption process was further characterised by differential scanning calorimetry, and the possible mechanism of the effects of NbF₅ addition is discussed.