High-capacity hydrogen storage in lithium and sodium amidoboranes

Abstract

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 economy. 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, NH"3BH"3, 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 (150C). However, the hydrogen purity suffers from the release of trace quantities of borazine. Here, we report that the related alkali-metal amidoboranes, LiNH"2BH"3 and NaNH"2BH"3, release 10.9wt and 7.5wt hydrogen, respectively, at significantly lower temperatures (90C) with no borazine emission. The low-temperature 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. © 2008 Nature Publishing Group.