Development of a hydrogen absorbing layer in the outer shell of high pressure hydrogen tanks

This study is focused on the development of a hydrogen absorbing Zr2Fe layer in the outer shell of high pressure (70 MPa) hydrogen storage tanks. This layer aims to absorb hydrogen coming from micro-cracks, as those formed by hydrogen embrittlement of the aluminium liner. A multi-phased Zr2Fe alloy prepared by induction melting presents a very fast absorption kinetic and a maximum absorption capacity of about 1.8 wt.%. The volume expansion upon hydrogen absorption reaches 19% and is very anisotropic. The good resistance to contamination of the Zr2Fe alloy is also demonstrated, since the absorption kinetic remains very fast after heating in air at 150 °C with the carbon fiber-epoxy resin composite used for the reinforcement of the high pressure storage vessel. Moreover, Zr2Fe ribbons can be prepared by melt-spinning. An annealing treatment above the recrystallization temperature of the amorphous phase (around 410 °C) is needed to obtain hydrogen absorption rate similar to that of induction-melted Zr2Fe alloy. However, the annealing leads to the limitation of the hydrogen capacity to 1.2 wt.%, due to the occurrence of an absorption–disproportionation phenomenon.