Effect of ball milling time on the hydrogen storage properties of TiF3-doped LiAlH4

In the present work, the catalytic effect of TiF3 on the dehydrogenation properties of LiAlH4 has been investigated. Decomposition of LiAlH4 occurs during ball milling in the presence of 4 mol% TiF3. Different ball milling times have been used, from 0.5 h to 18 h. With ball milling time increasing, the crystallite sizes of LiAlH4 get smaller (from 69 nm to 43 nm) and the dehydrogenation temperature becomes lower (from 80 °C to 60 °C). Half an hour ball milling makes the initial dehydrogenation temperature of doped LiAlH4 reduce to 80 °C, which is 70 °C lower than as-received LiAlH4. About 5.0 wt.% H2 can be released from TiF3-doped LiAlH4 after 18 h ball milling in the range of 60 °C–145 °C (heating rate 2 °C min−1). TiF3 probably reacts with LiAlH4 to form the catalyst, TiAl3. The mechanochemical and thermochemical reactions have been clarified. However, the rehydrogenation of LiAlH4/Li3AlH6 can not be realized under 95 bar H2 in the presence of TiF3 because of their thermodynamic properties.