Papers by Keyword: LiBH₄

Abstract: Nitrogen-doped ordered mesoporous carbon has been synthesized and used to confine LiBH₄ to improve its dehydrogenation properties. The carbon has a high BET specific surface up to 448.25 m²/g with pore size centered at 1.2 and 4.1 nm. The effects of ball milling time and speed on de-hydrogenation were investigated. The onset hydrogen desorption temperature of LiBH₄ is reduced to 100 °C by addition 40 wt% carbon, and it can release hydrogen of 8.3 wt% at 380 °C. Furthermore, cyclic dehydrogenation is studiedto estimate the stability of the samples in the present work.

Abstract: In the present study, Li-B-H films contained LiBH₄ and Li₂B₁₂H₁₂ were fabricated under different hydrogen pressures (20, 70 Pa) at ambient temperature by pulsed laser deposition (PLD). The corrosion behaviors of the films were studied over a time of 1-24 h in the air at ambient temperature. Fourier transform infrared spectrometry (FT-IR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) were used to analyze the formed oxidation film. The results indicated that an oxidation film with obvious cracks and holes were formed, which was composed by Li₂B₄O₇ and Li₂CO₃. The films were mainly reacted with H₂O and CO₂, so the oxidation of Li-B-H could be prevented by avoiding exposed to air.

Abstract: We describe approaches using modified carbon aerogels for increasing the weight loading of LiBH4. Large pore volume carbon aerogels were prepared with a sol-gel method and a polymethyl methacrylate (PMMA) microsphere template. Compared to those without using templates, the pore volume has been up to 3.8 times with a PMMA template. After incorporation into carbon aerogels, the weight loading of LiBH4 has reached 80%. Nitrogen absorption/desorption measurements show that more than 95% free space of carbon aerogels has been incorporated with LiBH4. Rama spectra suggest that there is no PMMA or chemical reaction during the synthesis of LiBH4/carbon aerogel composites.

Abstract: Interest in hydrogen as a future energy carrier in mobile applications has led to a strong increase in research on the structural properties of complex alkali metal and alkaline earth hydrides, with the aim to find structural phases with higher hydrogen densities. This contribution reviews recent work on the structural properties and phase diagrams of these complex hydrides under elevated pressures, an area where rapid progress has been made over the last few years. The materials discussed in greatest detail are LiAlH4, NaAlH4, Li3AlH6, Na3AlH6, LiBH4, NaBH4, and KBH4. All of these have been studied under high pressure by various methods such as X-ray or neutron scattering, Raman spectroscopy, differential thermal analysis or thermal conductivity measurements in order to find information on their structural phase diagrams. Based mainly on experimental studies, preliminary or partial phase diagrams are also given for six of these materials. In addition to this information, data are provided also on experimental results for a number of other complex hydrides, and theoretical predictions of new phases and structures under high pressures are reviewed for several materials not yet studied experimentally under high pressure.