Stress development of metal hydride composites for high density hydrogen storage applications

Strong mechanical forces can appear from gas absorbing solids if a volume expansion occurs during the chemical reaction. In particular for metal hydride reactors, the evolution of mechanical stresses on the reactor wall or internal assemblies over many hydrogen absorption/desorption cycles needs to be considered for reactor safety. In this work, we report on a recently developed in-situ measuring principle that allows the determination of mechanical stresses that originate from a metal hydride formation. For this purpose, a unique lab-scale reactor, equipped with a measuring cell, has been designed and tested with recently developed metal hydride composites (MHC). For spatially confined MHC we found that mechanical stresses were developed two and a half times higher than the hydrogen gas pressure applied for hydride formation.