Hydrogen storage properties of MgH2-SiC composites

This paper describes the effects of the addition of SiC on the hydrogen storage properties of MgH2 synthesized by ball milling. Transmission electron microscope images confirm that ultra-fine SiC particles are uniformly dispersed within the MgH2 matrix. It was found that the hydrogen absorption/desorption kinetics of MgH2 can be improved by the addition of a small amount of SiC (5 wt%). Higher level doping introduces negative effects, such as lower capacity, slower absorption/desorption rates, and higher hysteresis, compared to samples with lower SiC doping levels. It is believed that SiC can help to break up particles, reduce the grain size, and improve the surface area of MgH2, however, large amounts of SiC could also block the hydrogen diffusion path to some extent, which degrades the hydrogen absorption/desorption performance. (C) 2008 Elsevier B.V. All rights reserved.