Improvement of the LiBH4 hydrogen desorption by inclusion into mesoporous carbons

LiBH4 hydrogen desorption is strongly improved by its confinement to the nanoscale into a mesoporous carbon, prepared by the template method, having a pore diameter near 4nm and a porous volume of 1.1 cm(3) g(-1). The LiBH4/carbon composites are prepared by room temperature impregnations of the carbon matrixvvith LiBH4 solubilized within ethers. LiBH4/carbon composites with a 33:67 weight ratio show excellent desorption kinetics with a hydrogen release of 3.4wt.% in 90min at 300 degrees C, whereas the decomposition of neat LiBH4 is not significant at the same temperature. Moreover, both Differential Scanning Calorimetry and Thermal Desorption Spectroscopy experiments show that the hydrogen release for the 33:67 LiBH4/carbon composite occurs in one single step immediately above the LiBH4 melting temperature (280 degrees C) without any formation of intermediate compounds (like dodecaborane)as encountered with neat LiBH4. Such modification of the hydrogen release mechanism path was never reported for confined LiBH4 nanoparticles. Last the presence of the carbonaceous matrix is expected to be largely beneficial for handling the heat transfer associated with the endothermic character of the LiBH4 decomposition process. (C) 2009 Elsevier B.V. All rights reserved.