Hydrogen Release from Mixtures of Lithium Borohydride and Lithium Amide:  A Phase Diagram Study

Abstract

We recently reported the synthesis of a new quaternary hydride in the lithium-boron-nitrogen-hydrogen quaternary phase diagram with the approximate composition LiB0.33N0.67H2.67 having a theoretical hydrogen content of 11.9 wt %. This new compound forms by the reaction of appropriate amounts of lithium amide (LiNH2) and lithium borohydride (LiBH4) and releases greater than 10 wt % hydrogen when heated. A small amount of ammonia, 2-3 mol % of the generated gas, is also released. We now report a study of hydrogen and ammonia release from the series of reactant mixtures (LiNH2)x(LiBH4)1-x, where x=0.667 corresponds to the composition LiB0.33N0.67H2.67. We measured hydrogen and ammonia release amounts as a function of composition and found that maximum hydrogen and minimum ammonia release do occur for x=0.667. We also present evidence for an additional new quaternary phase and for two possibly metastable phases in this system.

Improving Effects of LiH and Co-Catalyst on the Dehydrogenation of Li4BN3H10

“…Meisner et al 13 17 and Pinkerton et al 20 reported the similar observation and claimed the necessity of heating for the disappearance of LiNH 2 . Shown in Figure 1 are the TPD and DSC spectra of pristine Li 4 BN 3 -H 10 , LiHÀLi 4 BN 3 H 10 , CoÀLi 4 BN 3 H 10 , and LiHÀCoÀLi 4 BN 3 H 10 samples.…”

Enhanced Electrical Conductivities of Complex Hydrides Li<SUB>2</SUB>(BH<SUB>4</SUB>)(NH<SUB>2</SUB>) and Li<SUB>4</SUB>(BH<SUB>4</SUB>)(NH<SUB>2</SUB>)<SUB>3</SUB> by Melting

“…For Li 2 (BH 4 )(NH 2 ), after melting and subsequent solidification, the original peaks disappear and, Fig. 1 (a 16,25) phase separations should occur in both Li 2 (BH 4 )(NH 2 ) and Li 4 (BH 4 )(NH 2 ) 3 after melting and subsequent solidification as follows (Fig. 4):…”

“…[15][16][17][18][19] Further, Li 2 (BH 4 )(NH 2 ) and Li 4 (BH 4 )(NH 2 ) 3 melt at temperatures around 360 K and 460 K, 16) indicating the possible enhancement of total ion conductivity in these temperature ranges. There has been no report on inorganic lithium fast-ion conductors with such low melting temperatures.…”

Promoted hydrogen release from 3LiBH4/MnF2 composite by doping LiNH2: Elimination of diborane release and reduction of decomposition temperature

“…To date, there is still lack of an efficient way to completely suppress B 2 H 6 formation during the decomposition of transition metal borohydrides. Recently, it has been revealed that no B 2 H 6 is present in evolved gas when the onset decomposition temperature of the (LiNH 2 ) 1ex /(LiBH 4 ) x system is controlled between 95 and 250 C by adjusting the mole ratio of amide and borohydride [12]. This gives us a hint that adding amides into transition metal borohydrides may suppress B 2 H 6 formation.…”