Hydrogen Storage in Li₃N:  Deactivation Caused by a High Dehydrogenation Temperature

Abstract

As a potential candidate for hydrogen storage, Li 3 N can absorb more than 9 wt % hydrogen. However, because of its incomplete dehydrogenation at a temperature of 280 °C, only about 5.5 wt % reversible hydrogen capacity could be reached. Although by increasing the temperature one can enhance dehydrogenation, this paper demonstrates that dehydrogenation of hydrogenated Li 3 N at the high temperature of 400 °C is followed by a very low (0.4 wt %) rehydrogenation capacity. Furthermore, scanning electron microscopy, Brunauer-Emmett-Teller surface area, and X-ray powder diffraction measurements have shown that both the sintering and the lattice structure change of Li 2 NH, which is a product of hydrogenation, might be responsible for such a major deactivation.

Cyclic Hydrogenation and Dehydrogenation Property of LiNH<SUB>2</SUB> Impregnated into Ni Foam

“…The powder sample is, on the other hand, found to be densely (almost no small pores and open spaces) sintered to form the conical shape coming from the inner shape of the crucible as a sample container. Sintering is one of the critical factors to degrade the cyclic hydrogenation and dehydrogenation property for LiNH 2 ; 10) the dehydrogenation of LiNH 2 at higher temperature (673 K) generates sintered particles covered with inactive and impervious skin layers. This may correspond to the isolation of hydrogen from the sintered sample, resulting in degradation of the hydrogenation and dehydrogenation property.…”

Li3−xMxN (M=Co, Ni) synthesized by Spark Plasma Sintering for hydrogen storage

“…Due to incomplete dehydrogenation at a temperature of 255 • C only ∼5.8 wt% reversible hydrogen capacity can be obtained. Although one can enhance dehydrogenation by increasing the temperature, some authors demonstrate that dehydrogenation of hydrogenated Li 3 N at a temperature of 400 • C is followed by a very low (0.4 wt%) rehydrogenation capacity [7]. Ab initio calculations show that partial substitution of Li by transition metals like Cu or Ni can reduce the reaction enthalpy between amide and imide [8].…”

Ternary nitrides for hydrogen storage: Li–B–N, Li–Al–N and Li–Ga–N systems

“…Li 3 N absorbs hydrogen at high temperatures in a twostep process, transforming into LiH and LiNH 2 in an overall reaction that corresponds to a take-up of 11.5 wt.% hydrogen [3]. However, owing to incomplete hydrogenation, less than 6 wt.% hydrogen is reversibly stored below 280 • C [4]. Many attempts have been made to enhance the hydrogen storage properties of this promising system, such as the addition of various catalysts [5][6][7], and the partial substitution of Li by Mg [8][9][10].…”