Insight into the decomposition pathway of the complex hydride Al3Li4(BH4)13

The decomposition pathway of the complex hydride Al3Li4(BH4)13 is in the focus of this study. Initially the compound attracted great interest due to its high H2 capacity (17.2 wt.%) and desorption at moderate temperatures (<100 °C). This work sheds light on its decomposition reaction by a unique experimental setup of thermogravimetry combined with spectroscopic gas phase analysis (FT-IR and MS) at ambient conditions. It is observed that the compound itself is metastable and decomposes immediately into its components, solid LiBH4 and Al(BH4)3 which is monitored in the gas phase. Carbon addition decreases the observed mass loss and the spectroscopic gas phase analysis is used to learn about the impact of carbon addition.

► Clarification of high mass loss during decomposition of Al3Li4(BH4)13.
► Decomposition monitored by thermogravimetry and FT-IR analysis of the gas phase.
► Desorption of volatile Al(BH4)3, B2H6 and H2 proven by combined FT-IR and MS.
► Al3Li4(BH4)13 initially decomposes into its components Al(BH4)3 and LiBH4.
► Impact of carbon addition analysed by this unique setup.