Aluminum Chloride as effective dopant in Amide-based systems

S. GARRONI; V. PISANO; L. FERNÁNDEZ ALBANESI; C. PISTIDDA; A. SANTORU; E. NAPOLITANO; C. MILANESE; G. MULAS; S. ENZO; F. C. GENNARI

Warsaw

Congreso; E-MRS 2017 Fall Meeting; 2017

European Materials Research Society

In the field of the hydrogen storage technology, large interest has been addressed towards a class of materials based on metal amides, due to their high hydrogen gravimetric densities and good reversibility [1]. Among them, bicomponent systems such as LiNH2/Mg(NH2)2/NaNH2/Ca(NH2)2 ? LiH/MgH2 are still considered appealing candidates for practical applicationsas a consequence of their encouraging thermodynamic properties close to the desired targets.However, the total amount of hydrogen released in these systems, rarely can be achieved within reasonable times. This limit is often ascribable to the severe kinetic barrier related with the sorption reactions of the systems analyzed. To this, different strategies have been inspected to improve the hydrogen sorption performance, although kinetic constraints have been partially alleviated but not totally overcome. Recent studies have drawn attentions to AlCl3, a powerful Lewis acid, as efficient additive able to improve significantly the hydrogen storage properties of different amide-based systems such as LiNH2-1.6LiH composite [2, 3]. The unique reactivity of AlCl3 with amides, in particular when ball milled, allows to form new Al and Cl rich hydride phases with enhanced kinetic properties with respect to the un-doped systems. The present contribution aims at providing an overview on the experimental attempts addressing the structural and hydrogen storage properties of different metal amide - hydride systems doped by AlCl3. Particular emphasis will be addressed to the formation of new halide-hydride, Li-Al-Cl-N-H, phases formed by the interaction of the starting reactants and which play a key role in the reversible hydrogen storage of the system. The reaction pathways and the possible intermediates formed during the milling andafter the heating under hydrogen pressure, together with the hydrogen desorption/absorption properties of the studied systems, will be also discussed in detail.