Synthesis and characterization of polymer embedded LaNi5 composite material for hydrogen storage

Composite materials consisting of powders of a standard hydride forming an intermetallic compound (LaNi5) dispersed into a hydrogen-permeable elastomer (polysiloxane) have been produced. The H-2 storage capacity and the hydrogen desorption kinetics have been measured with composite samples having a metal content of 50 and 83 wt%. At a metal content of 50 wt%, the composite material consists of separated LaNi5 particles embedded into the polymeric matrix: this composite sample shows low H-2 storage capacity that is attributed to the chemistry of the metal-polymer interface limiting the H-2 absorption by the metallic particles. The amount of absorbed hydrogen significantly increases at the metal content of 83%, when a percolative distribution is assumed by the metallic particles which are connected through a high volumetric density of metal-metal interfaces. The rate limiting process in the hydrogen desorption kinetics is attributed to the H diffusion process in the metallic fraction of the composite.