Hydrogen storage properties of LiNH2-LiH system with MgH2, CaH2 and TiH2 added

G. AMICA; P. ARNEODO LAROCHETTE; F. C. GENNARI

INTERNATIONAL JOURNAL OF HYDROGEN ENERGY

PERGAMON-ELSEVIER SCIENCE LTD

Lugar: Amsterdam; Año: 2015 vol. 40 p. 9335 - 9346

0360-3199

The addition of different metal hydrides to LieNeH system offers a possible way to modify its thermodynamic properties and/or the dehydrogenation/hydrogenation kinetics. In this paper we report the hydrogen storage properties of LiNH2eLiH system with MH2 added (M = Mg, Ca, Ti) and clarify the chemical interactions occurring during hydrogen cycling. Detailed structural investigations reveal that during heating under hydrogen, MH2 (M = Mg, Ca) reacts with LiNH2 to form Li2Mg(NH)2 and 2CaNHeCa(NH2)2 solid solution, withsimultaneous hydrogen release. Formation of the Li2NHeCaNH mixture after dehydrogenation of the LiNH2eLiH with CaH2 added is proved by XRPD and FTIR, providing a new reversible pathway for hydrogen storage in the LieCaeNeH system. Notable improvement in the dehydrogenation temperature and kinetics was observed for LiNH2eLiH system with CaH2 and MgH2 added, without clear effects in the case of TiH2. The kinetic analysis reveals that dehydrogenation process is diffusion-controlled and the beneficial effect of MgH2 and CaH2 is due to the enhancement of Li mobility.