Dependence of hydrogen storage characteristics of Mg–TiFe 0.92Mn 0.08 composite on amount of TiFe 0.92Mn 0.08

Abstract

We investigated the hydrogen storage characteristics of Mg– x wt.%TiFe 0.92Mn 0.08 ( x = 20 , 35, and 50) composites prepared by wet mechanical milling. TiFe 0.92− x Mn 0.08 and α -Fe phases were formed in these composites by the decomposition of TiFe 0.92Mn 0.08 after activation. The kinetics of the hydrogen absorption at low temperature was improved by increasing the amount of TiFe 0.92Mn 0.08. These improvements appear to be attributable to the TiFe 0.92− x Mn 0.08 phase, which plays an important role as a pathway for the diffusion of hydrogen into the Mg matrix. In contrast, the hydrogen desorption temperature decreased as the amount of α -Fe originating from TiFe 0.92Mn 0.08 increased. The Mg–50 wt.%TiFe 0.92Mn 0.08 composite started to desorb hydrogen at the same temperature as Mg–50 wt.%Fe composite prepared under the same milling conditions although the former had much better hydrogen absorption characteristics than the latter at low temperature. We consider that the presence of α -Fe probably contributes to the improvement in the hydrogen desorption characteristics.