High-capacity hydrogen storage in lithium and sodium amidoboranes

The safe and efficient storage of hydrogen is widely recognized as one of the key technological challenges in the transition towards a hydrogen-based energy economy1,2. Whereas hydrogen for transportation applications is currently stored using cryogenics or high pressure, there is substantial research and development activity in the use of novel condensed-phase hydride materials. However, the multiple-target criteria accepted as necessary for the successful implementation of such stores have not yet been met by any single material. Ammonia borane, NH3BH3, is one of a number of condensed-phase compounds that have received significant attention because of its reported release of ˜12wt% hydrogen at moderate temperatures (˜150 °C). However, the hydrogen purity suffers from the release of trace quantities of borazine. Here, we report that the related alkali-metal amidoboranes, LiNH2BH3 and NaNH2BH3, release ˜10.9wt% and ˜7.5wt% hydrogen, respectively, at significantly lower temperatures (˜90 °C) with no borazine emission. The lowtemperature release of a large amount of hydrogen is significant and provides the potential to fulfil many of the principal criteria required for an on-board hydrogen store.