International Journal of Hydrogen Energy, Vol.42, No.22, 15262-15270, 2017
Enhanced hydrogen storage performances of LiBH4 modified with three-dimensional porous fluorinated graphene
Novel fluorinated graphene (FG) nano-sheets with three-dimensional (3D) porous structure were synthesized by one-pot hydrothermal reaction, and then ball milled with LiBH4 to prepare the hydrogen storage composite material. The LiBH4 with 20 wt.% FG composite begins to release hydrogen at 204 degrees C, 120 degrees C lower than that of pure LiBH4. Moreover, it can release 3.45 wt.% hydrogen at 400 degrees C within 1000 s, which is 2.57 times faster than pure LiBH4. The reversibility of the LiBH4-FG composite also has been enhanced, its absorption capacity still reaches 78.6% of initial hydrogen uptake at the 4th cycle. According to the phase composition analyses, F- can partially substitute the anionic H in LiBH4 or LiH, resulting in a favorable thermodynamic modification. Additionally, the activation energy (Ea) of hydrogen desorption of LiBH4 is reduced from 181.80 kJ/mol to 130.87 kJ/mol. The remarkably improved hydrogen storage performances of LiBH4 are largely attributed to the combined effects of the nano-modifying and the function of F anion of the FG. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.