Improved hydrogen desorption properties of LiBH4 by AlH3 addition

Lithium borohydride (LiBH4) possesses a very high hydrogen capacity (18.5 wt%) but suffers from high thermal stability. In this work, the as-prepared aluminium hydride (AlH3) was ball milled with LiBH4 forming 2LiBH(4) + AlH3 composite to improve the hydrogen desorption properties of LiBH4. Hydrogen desorption measurements showed that a hydrogen capacity of 11.2 wt% is obtained from the 2LiBH(4) + AlH3 composite and the desorption temperature of LiBH4 with AlH3 addition is reduced by more than 30 degrees C. AlH3 is better as an Al source than the as-received Al in that the hydrogen desorption extent of AlH3-doped LiBH4 reaches 70%, while it is 54% and 61% for the pure LiBH4 and the Al-doped LiBH4. This is due to the brittle and oxide-free nature of AlH3. Microstructure investigations showed that during heating process, the 2LiBH(4) + AlH3 composite undergoes AlH3 decomposition forming Al* and releasing hydrogen, followed by the decomposition of LiBH4. LiBH4 will react with Al* forming AlB2 and Li-Al-B compounds during its decomposition, which contributes to the improved hydrogen desorption properties of LiBH4. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.