Multielement synergetic effect of NiFe2O4 and h-BN for improving the dehydrogenation properties of LiAlH4

Abstract

Effective hydrogen storage is one of the main unresolved challenges towards deploying the so-called hydrogen economy. LiAlH₄ is considered a promising candidate for hydrogen storage due to its high hydrogen storage capacity and the relative abundance of aluminum. However, it also has the disadvantages of slow kinetics, high dehydrogenation temperature and poor reversibility. To improve these shortcomings of LiAlH₄, we made a composite material by incorporating hexagonal boron nitride supported NiFe₂O₄ (NiFe₂O₄@h-BN) into it. We then studied the effect of NiFe₂O₄@h-BN composites on the dehydrogenation and rehydrogenation behaviors of LiAlH₄ using thermogravimetric analysis, mass spectrometry and the Sieverts-type pressure composition temperature. The results showed that the onset decomposition temperature of LiAlH₄ doped with 7 wt% NiFe₂O₄@h-BN is 77.1 °C with 6.74 wt% hydrogen released. In addition, under 30 bar pressure hydrogen and at 300 °C constant temperature, the LiAlH₄ doped with 7 wt% NiFe₂O₄@h-BN after dehydrogenation absorbed nearly 0.6 wt% of hydrogen in 11 hours. At the same time, Al₄Ni₃ and LiFeO₂ were found in LiAlH₄ doped with NiFe₂O₄@h-BN after ball milling, and Al_1.1Ni_0.9 was obtained during heating.