Enhanced hydrogen reversibility of nanoconfined LiBH4–Mg(BH4)2

Abstract

This study shows the hydrogen desorption kinetics and reversible hydrogen storage properties of 0.55LiBH4–0.45Mg(BH4)2 melt-infiltrated in different nanoporous carbon aerogels with different BET surface areas of 689 or 2660 m2/g and pore volumes of 1.21 or 3.13 mL/g. These investigations clearly show a significantly improved hydrogen storage capacity after four cycles of hydrogen release and uptake for bulk 0.55LiBH4–0.45Mg(BH4)2 and infiltrated in carbon aerogel and the high surface area scaffold, where 22, 36 and 58% of the initial hydrogen content remain after four cycles of hydrogen release and uptake, respectively. Nanoconfinement in high surface area carbon aerogel appears to facilitate hydrogen release illustrated by release of 13.3 wt% H2 (93%) and only 8.4 wt% H2 (58%) from bulk hydride in the first cycle using the same physical condition. Notably, nanoconfinement also appear to have a beneficial effect on hydrogen uptake, since 8.3 wt% H2 (58%) is released from the high surface area scaffold and only 3.1 wt% H2 (22%) from the bulk sample during the fourth hydrogen release.