Hydrogen storage in Mg–Mg2Ni–carbon hybrids

Abstract

Mg-based hybrids have potential applications for hydrogen storage in the solid state. In the current investigation laminate hybrids were prepared keeping this objective in view. Mg2Ni was synthesized from vacuum induction melting of metal ingots, which was further incorporated between the Mg layers by Accumulative Roll Bonding process (ARB). To improve the hydrogen storage properties, carbon (soot/graphite) was also deposited between the Mg layers. By using the ARB process, microstructure refinement was achieved, along with the incorporation of about 5wt.% Mg2Ni and 1.3wt.% soot (or 5wt.% graphite) in the hybrid. A total of 30 ARB passes were used in the process. The hydrogen absorption characteristics of the hybrid (through pressure–composition isotherms and absorption–time curves) were studied using a standard Sieverts apparatus. Absorption of about 6.2wt.%H was observed at 300°C at ∼3.5bar pressure in the Mg–Mg2Ni–graphite hybrids (5.8wt.%H at a plateau pressure of ∼2bar). Good kinetics of absorption was also observed, i.e. 4.5wt.%H was absorbed in ∼80s at 300°C under 20bar H2 pressure.