Magnesium is considered as one of the most attractive materials for hydrogen storage because of its high hydrogen storage capacity and abundance. However, slow hydrogen absorption/desorption kinetics, high hydride formation enthalpy and poor thermal conductivity of the hydride phase are the main drawbacks that prevent its use in hydrogen storage. The issues are interconnected: low thermal conductivity slows down the heat flow that influences the rate of hydrogen absorption/desorption.
In this work we synthesized solid porous compacts of pure Mg and Mg - 2 wt.% multi-wall carbon nanotubes (MWCNTs) composite processed by high energy ball-milling. We studied a correlation between the morphology and the thermal conductivity in the hydrogenated compacts which absorbed up to 80-90% of their maximum theoretical hydrogen storage capacity. It was found that although prolonged ball-milling leads to a partial destruction of the MWCNTs and formation of carbon nanoparticles, it has a positive effect on the thermal conductivity of the pellets. The role of carbonaceous derivatives of the MWCNTs in enhancing thermal conductivity of the pelletized compacts is discussed.
This work was supported by the Israel Strategic Alternative Energy Foundation (I-SAEF).
