Hydrogen generation from noncatalytic hydrolysis of LiBH 4/NH 3BH 3 mixture for fuel cell applications

Abstract

Ammonia borane (NH 3BH 3) and lithium borohydride (LiBH 4) are promising hydrides as they contain 19.6 wt.% and 18.5 wt.% hydrogen respectively. However, hydrolysis of NH 3BH 3 needs catalysts or high temperature to initiate the release of hydrogen. On the other hand, hydrolysis of LiBH 4 is incomplete, because the agglomeration of LiBH 4 and its products limits its full utilization. In the present work, hydrolysis performance of LiBH 4/NH 3BH 3 mixture was investigated. The results show that LiBH 4/NH 3BH 3 mixture can fully release its theoretical amount of hydrogen at room temperature without catalysts. In the presence of LiBH 4, NH 3BH 3 can be fully hydrolyzed at room temperature. In return, in the presence of NH 3BH 3, the agglomeration can be avoided resulting in a complete hydrolysis process. Our results indicate that the improvements are attributed to the intermolecular electron migration between LiBH 4 and NH 3BH 3, which changes the reactivity of these compounds. Hydrolytic heat of LiBH 4 also contributes to the promoted hydrolysis of NH 3BH 3. Our results present a novel strategy for noncatalytic hydrolysis of NH 3BH 3 and LiBH 4 for proton exchange membrane fuel cell applications.