H 2 storage efficiency and sorption kinetics in composite materials

Abstract

We have prepared two different kinds of composite materials for hydrogen storage and studied their H 2 storage capacity and desorption kinetics. The first composite material consists of magnesium-containing transition metal nanoclusters distributed in the Mg matrix (Mg:TM): this composite material shows better H 2 desorption performances than pure Mg. This improvement is attributed to the role of the MgH 2-TM nanocluster interface as preferential site for hexagonal Mg (h-Mg) nucleation and to the rapid formation of interconnected h-Mg domains where H diffusion during desorption occurs. The second composite material consists of LaNi 5 particles (size<30 μm) distributed in a polymeric matrix. The H 2 storage capacity is negligible at low metal content (50 wt%) when the metal particles are completely embedded in the polymeric matrix. The H 2 storage capacity is comparable to that of the pure LaNi 5 powders at high metal content (80 wt%) when a percolative distribution is assumed by the LaNi 5 particles: this evidence points out the role of metal–metal interfaces and of interconnected metallic networks for H transport.