Stuffing in the hydrogen – Lithium Boro-hydride

What does it look like?

Crystal structure of lithium boro-hydride, the light green atoms are lithium, dark green boron and pink are hydrogen. Image generated by the VESTA (Visualisation for Electronic and STructural analysis) software http://jp-minerals.org/vesta/en/

What is it?

One solution to our society's dependence on carbon dioxide emitting fossil fuels is the suggestion that we move to a 'hydrogen economy'. The idea is that we can abundantly form hydrogen, and on releasing its energy produce water as a waste product. But one of the challenges facing this route has been how to store it! Conventional high-pressure tanks of hydrogen gas are expensive and heavy (and a little dangerous). So in came crystallography to look for solids with a high-density hydrogen content!

There have been lots of promising candidates for this, principally hydrides formed when hydrogen reacts with metals like magnesium and sodium. There was an issue with these however. The hydrogen atoms within them were bound too tight – it would cost too much energy to release them. So one potential solution to this was this material, lithium boro-hydride, where the borons don't hold onto the hydrogens quite as tight.

Where did the structure come from?

The structure we've featured comes from work by Soulié et al., published in 2002. They investigated the structure of Lithium boro-hydride and also found a new polymorph that forms at high-temperature. The crystal structure data for this study can be found in the Cambridge Structral Database, refcode XIHFAW03.

Tags: hydrogen   hydride   inorganic