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 H2 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 H2 storage capacity that is attributed to the chemistry of the metal polymer interface limiting the H2 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.