Role of Li₂B₁₂H₁₂ for the Formation and Decomposition of LiBH₄

Abstract

By in situ X-ray diffraction (XRD) and nuclear magnetic resonance (NMR) spectroscopy, the role of Li<SUB>2</SUB>B<SUB>12</SUB>H<SUB>12</SUB> for the sorption of LiBH<SUB>4</SUB> is analyzed. We demonstrate that Li<SUB>2</SUB>B<SUB>12</SUB>H<SUB>12</SUB> and an amorphous Li<SUB>2</SUB>B<SUB>10</SUB>H<SUB>10</SUB> phase are formed by the reaction of LiBH<SUB>4</SUB> with diborane (B<SUB>2</SUB>H<SUB>6</SUB>) at 200 °C. Based on our present results, we propose that the Li<SUB>2</SUB>B<SUB>12</SUB>H<SUB>12</SUB> formation in the desorption of LiBH<SUB>4</SUB> can be explained as a result of reaction of diborane and LiBH<SUB>4</SUB>. This reaction of the borohydride with diborane may also be observed for other borohydrides, where B<SUB>12</SUB>H<SUB>12</SUB> phases are found during decomposition.