Hydrogen Storage Properties of Zr-Based AB2-x Mx Metal Hydrides Made by Hydriding Combustion Synthesis (HCS)

This study investigated the hydrogen storage properties of Zr-Based AB(2-x)M(x) metal hybride made by HCS (Hydriding Combustion Synthesis). The materials were prepared by HCS 80 wt% AB2-15 wt% Mg5 wt% Mm, HCS 80 wt% AB2-20 wt% Mg and pure Zr-Based AB2, These materials were activated at 298 K under 20 bar. Both HCS 80 wt% AB2-20 wt% Mg and HCS 80 wt% AB2-15 wt% Mg-5 wt% Mm were absorbed within 1 minute. In the case of the AB2, it was perfectly absorbed within 6 minutes. Then, the materials were evaluated to obtain P-C-T (Pressure-Composition-Temperature) curves at 298K. As a result, the hydrogen storage capacity of HCS 80 wt% AB2-20 wt% Mg, HCS 80 wt% AB2-15 wt% Mg-5 wt% Mm and pure Zr-Based AB2 were determined to be 1.2, 1.6 and 1.74 wt%, respectively. The activation energy and rate controlling step were calculated by the Johnson-Mehl Avrami equation. The activation energies of HCS 80 wt% AB2-20 wt% Mg, HCS 80 wt% AB2-15 wt% Mg-5 wt% Mm and pure Zr-Based AB2 were 26.91, 20.45, and 60.41 kJ/mol, respectively. Also, the values of 11 in the Johnson-Mehl Avrami equation for HCS 80 wt% AB2-20 wt% Mg, HCS 80 wt% AB2-15 wt% Mg-5 wt% Mm and pure Zr-Based AB2 are 0.60, 0.51, and 0.44. So, the rate controlling steps which indicate hydrogen storage mechanism are an one dimensional diffusion process.