Improved dehydrogenation performance of LiAlH₄ doped with BaMnO₃

Due to its high gravimetric capacity of hydrogen (10.5 wt%), LiAlH₄ has been regarded as a promising material for solid-state hydrogen storage material for onboard usage. However, high decomposition temperature, poor kinetics and irreversibility retard its application. To counter this problem, various weight percentages of BaMnO₃ are introduced into the LiAlH₄ system as an additive in this work. As a result, the starting hydrogen release of LiAlH₄ was reduced to 109-115 °C and the second desorption temperature occurred at around 134-158 °C, much lower than pure LiAlH₄. The isothermal desorption kinetics also proved that faster desorption kinetics can be observed at 90 °C for 80 min. About 2.00-2.60 wt% of H₂ could be desorbed by the composite, whereas only <1.00 wt% of H₂ was desorbed by undoped LiAlH₄. Additionally, adding BaMnO₃ reduced the activation energies by 30 kJ/mol for the first stages and 34 kJ/mol for the second stages. Based on the X-ray diffraction result, the active species formed of MnO₂ and Ba or Ba-containing materials are believed to be responsible for the noticeable enhancement in the desorption properties of LiAlH₄.