Poor reversibility and high desorption temperature restricts the practical use of lithium borohydride (LiBH4 ) as an advanced hydrogen store. Herein, a LiBH4 composite confined in unique double-layered carbon nanobowls prepared by a facile melt infiltration process is demonstrated, thanks to powerful capillary effect under 100 bar of H2 pressure. The gradual formation of double-layered carbon nanobowls is witnessed by transmission electron microscopy (TEM) observation. Benefiting from the nanoconfinement effect and catalytic function of carbon, this composite releases hydrogen from 225 °C and peaks at 353 °C, with a hydrogen release amount up to 10.9 wt%. The peak temperature of dehydriding is lowered by 112 °C compared with bulk LiBH4 . More importantly, the composite readily desorbs and absorbs ≈8.5 wt% of H2 at 300 °C and 100 bar H2 , showing a significant reversibility of hydrogen storage. Such a high reversible capacity has not ever been observed under the identical conditions. The usable volumetric energy density reaches as high as 82.4 g L-1 with considerable dehydriding kinetics. The findings provide insights in the design and development of nanosized complex hydrides for on-board applications.
Keywords: hydrogen storage materials; hydrogen storage reversibility; lithium borohydride; metal complex hydrides; nanoconfinement.
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