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

Abstract:

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 …

Año de publicación:

2018

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Fuente:

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