Role of aluminum chloride of the reversible hydrogen storage properties of the Li-N-H system

LUISA FERNÁNDEZ ALBANESI; SEBASTIANO GARRONI; PIERRE ARNEODO LAROCHETTE; PAU NOLIS; GABRIELE MULAS; STEFANO ENZO; MARÍA DOLORS BARÓ; FABIANA C. GENNARI

INTERNATIONAL JOURNAL OF HYDROGEN ENERGY

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2015 vol. 40 p. 13506 - 13517

0360-3199

In order to understand the role of AlCl3 addition on the LieNeH system, we have systematicallyinvestigated the hydrogen sorption kinetics and the reactions between LiNH2eLiH and AlCl3 additive with a multitechnique approach involving differential scanningcalorimetry (DSC), hydrogen volumetric measurements, X-ray powder diffraction (XRPD),Fourier transform infrared analysis (FTIR) and solid-state nuclear magnetic resonance(NMR). Different interactions were identified as a function of the amount of added AlCl3.For low AlCl3 addition (0.03 mol), the Al3þ is incorporated into the interstitial sites by theLiNH2 structure. When AlCl3 amount increased (0.08 and 0.13 mol), the formation of newamide-chloride phases were detected by XRPD and indexed with cubic and hexagonal LieAleNeHeCl geometries. Occurrence of such new phases was also confirmed by FTIR andNMR. The formation of these new LieAleNeHeCl phases modifies the kinetics as well asthe thermodynamic behavior of the original LieNeH system. Interesting, in all AlCl3-dopedcomposites, hydrogen was stored reversibly with faster sorption kinetics than un-doped LieNeH system and with a significant reduction of NH3 emission. This improvement can beassociated with the Al3+ incorporation into LiNH2 that promotes the migration of Liþ, whilefor high AlCl3 doping, the formation of new phases LieAleNeHeCl also weakens the NeHbond.