Nano-Ni doped Li-Mn-B-H system as a new hydrogen storage candidate

In this work, we report the synthesis and characterization of LiMn(BH4)(3), member of a new class of complex borohydrides for hydrogen storage. This new complex hydride was prepared with a 3:1 ratio of precursor materials LiBH4 and MnCl2 via the solid-state mechano-chemical process. The B-H stretch occurrence at 2374 cm(-1) in addition to two other B-H bonding bands of LiBH4 (2228 and 2297 cm(-1)) from the FTIR investigation confirm the formation of LiMn(BH4)(3) at room temperature. Thermogravimetric analysis (TGA) of LiMn(BH4)(3) indicated that a large amount of hydrogen (similar to 8.0 wt%) can be released between 135 and 155 degrees C in a single dehydrogenation reaction step. Reduction in the decomposition temperature was achieved by doping this Li-Mn-B-H system with small fractions of nano-Ni. An amount of 1.5 mol% nano-Ni was estimated and found to be the optimum concentration for effective decomposition. Nano-Ni loading in the host hydride lowers the melting and thermal decomposition temperatures (at least by 20 degrees C) as evidenced from the simultaneous TGA, DSC and TPD measurements. The doped LiMn(BH4)(3) exhibits lower activation energy (112 kJ/mole) by 20 kJ/mole as compared to the undoped sample (131 kJ/mole). Moreover, the gas chromatography studies of the undoped and doped LiMn(BH4)(3) demonstrate that the evolved gas is mainly hydrogen and does not contain members of the borane family. (C) 2009 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.