Superior dehydrogenation performance of nanoscale lithium borohydride modified with fluorographite

Abstract

A significant enhancement in the dehydrogenation performance of LiBH4 is achieved by modifying with fluorographite (FGi). In-depth investigations show that the dehydrogenation thermodynamics and kinetics of LiBH4 are strongly improved by ball milling LiBH4 with FGi. The ball-milled LiBH4–FGi (mass ratio of 1:1) composite starts to release hydrogen without impurity gas at around 180 °C, and obtains a hydrogen desorption capacity of 7.2 wt% below 200 °C in seconds, which is improved dramatically compared with pristine ball-milled LiBH4. Microscopic morphology indicates that numerous ∼90 nm spots formed on the surface of FGi. Based on the microstructure analyses combined with hydrogen storage performances, the prominent effect of FGi is largely attributed to the nano-modifying effect and the exothermic reaction between LiBH4 and FGi during the dehydrogenation process. Furthermore, partial reversibility of the LiBH4–FGi composite has been demonstrated and the mechanism underlying the cycling capacity loss is discussed. The use of FGi may shed light on future study on searching for new strategies to improve both the thermodynamics and kinetics of light-metal complex hydrides.