Dehydrogenation and rehydrogenation of a 0.62LiBH4-0.38NaBH4 mixture with nano-sized Ni

• Published in: International journal of hydrogen energy 2018-08, Vol.43 (34), p.16782-16792
• Main Authors: Liu, Yinzhe, Heere, Michael, Contreras Vasquez, Luis, Paterakis, Christos, Sørby, Magnus H., Hauback, Bjørn C., Book, David
• Format: Article
• Language: English
• Subjects: Dehydrogenation; Eutectic borohydrides; Hydrogen storage; Nanomaterial; Reaction pathways; Rehydrogenation
• ISSN: 0360-3199; 1879-3487
• DOI: 10.1016/j.ijhydene.2018.04.211

The dehydrogenation reaction pathway of a 0.91 (0.62LiBH4-0.38NaBH4)-0.09Ni mixture in the temperature range of 25–650 °C in flowing Ar and the cycling stability in H2 are presented. No H2 is released immediately after melting at 225 °C. The major dehydrogenation occurs above 350 °C. Adding nano-sized Ni reduces the dehydrogenation peak temperatures by 20–25 °C, leading to three decomposition steps where Ni4B3 and Li1.2Ni2.5B2 are found in the major dehydrogenation products for the 1st and the 3rd step; whilst the Ni-free mixture decomposes through a two-step decomposition pathway. A total of 8.1 wt% of hydrogen release from the 0.91 (0.62LiBH4-0.38NaBH4)-0.09Ni mixture is achieved at 650 °C in Ar. This mixture has a poor hydrogen cycling stability as its reversible hydrogen content decreases from 5.1 wt% to 1.1 wt% and 0.6 wt% during three complete desorption-absorption-cycles. However, the addition of nano-sized Ni facilitates the reformation of LiBH4. •0.91 (0.62LiBH4-0.38NaBH4)-0.09Ni releases 8.1 wt% H2 (RT-650 °C) in Ar.•Nano-sized Ni destabilises the dehydrogenation leading to a three-step reaction.•Adding nano-sized Ni does not improve the hydrogen storage cycling stability.•Adding nano-sized Ni facilitates the reformation of LiBH4 during cycling.