Destabilized LiBH4−NaAlH4 Mixtures Doped with Titanium Based Catalysts

We investigate the hydrogen storage properties of the mixed complex hydride LiBH 4 −NaAlH 4 system, both undoped and doped with a TiCl 3 additive. The mixed system is found to initiate a transformation to LiBH 4 −NaAlH 4 after ball-milling, and the doped system is found to have a significant lower hydrogen release temperature compared to the undoped system and that of titanium doped LiAlH 4 and NaAlH 4 systems. Three dehydrogenation steps with a total of 3.5 wt % released hydrogen are observed for samples with a 2:3 molar ratio, when heated to ∼210 °C under a constant heating ramp in a 1 bar helium atmosphere. A slow hydrogen release is also observed at room temperature in the freshly ball-milled powders due to decomposition of the formed LiAlH 4 . X-ray powder diffraction spectra shows that the first dehydrogenation step is completed after a couple of days at room temperature. LiNa 2 AlH 6 is found in NaAlH 4 rich mixtures at higher temperature, and this phase is found to reversibly discharge and recharge hydrogen at 80 bar and 180 °C.