Effect of multiwall carbon nanotubes on absorption /desorption kinetics in MgH2

M. G. VERÓN; H. TROIANI; F. C. GENNARI

Moscú, Rusia

Simposio; International Symposium on Metal-Hydrogen Systems-Fundamentals and Applications; 2010

International Symposium on Metal-Hydrogen Systems

    Metal hydrides are a promising alternative for hydrogen storage in mobile applications. MgH2 is an attractive candidate due to its high storage capacity (7.6wt %), abundance in the earth crust and low cost. However its unfavorable absorption and desorption kinetics have hindered its practical application for on-broad hydrogen storage. Various alternatives such as mechanical milling and the addition of catalysts have been applied to solve this difficulty. In the present work, the effect of milling time and of the addition of 5 wt% multiwall carbon nanotubes on the kinetics sorption of MgH2-5wt% Co mixture was studied. With this purpose, 5 wt% multiwall carbon nanotubes (MWCNT) were added to a mixture of MgH2-5wt% Co previously milled for 50 hours in a high energy mill. The microstructure, structure and thermal behavior of the formed phases were investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC).  The hydrogen storage capacity and kinetic properties of the reaction with hydrogen were determined by using a modified Sieverts-type equipment. Improved storage capacity and absortion/desorption kinetics were observed for the sample MgH2-5wt% Co with 5 wt% MWCNT milled for 5 hours (Fig.1). This result can be attributed to the combined effect of additional diffusion paths provided by carbon nanotubes [1, 2], the catalytic role of Co in the dissociation of hydrogen molecule and the milling time. The correlation between microstructure and nature of the phases formed during hydrogen cycling on the sorption properties of MgH2 for hydrogen storage applications are analyzed.