Improved Reversible Dehydrogenation of Lithium Borohydride by Milling with As-Prepared Single-Walled Carbon Nanotubes

Single-walled carbon nanotubes (SWNTs) were mechanically milled with lithium borohydride (LiBH4) and examined with respect to its effect on the reversible dehydrogenation reactions of LiBH4. It was found that as-prepared SWNTs possess pronounced promoting effects on the dehydrogenation/rehydrogenation reactions of LiBH4, thus rendering the composite material reversible hydrogen storage at markedly reduced operation temperature and pressure conditions. For the LiBH4−30 wt % SWNTs composite milled for 1 h, 11.4 wt % hydrogen can be discharged within 50 min at 450 °C; over 6.0 wt % hydrogen can be recharged at 400 °C under an initial hydrogen pressure of 10 MPa. The systematic property/phase/structure studies of the LiBH4−SWNTs composite and related materials suggest that the observed property enhancement should be understood as combined effects of the metal nanoparticles or their borides, and carbon nanotubes. Additionally, the mechanism underlying the characteristic capacity loss in the dehydrogenation/rehydrogenation cycles of LiBH4 was also discussed.