MgCNi3 prepared by powder metallurgy for improved hydrogen storage properties of MgH2

Abstract

With the depletion of global energies resources, improvement of hydrogen storage properties of materials like MgH2 is of great interest for future efficient renewable resources. In this study, a novel antiperovskite MgCNi3 was synthesized by powder metallurgy then introduced into Mg to fabricate MgMgCNi3 composite. The hydrogen storage properties of the obtained MgMgCNi3 composite were evaluated. MgMgCNi3 showed a high capacity of hydrogen storage and fast kinetics of hydrogen uptake/release at relatively low temperatures. About 4.42 wt% H2 was absorbed within 20 min at 423 K, and 4.81 wt% H2 was reversibly released within 20 min at 593 K. By comparison, milled MgH2 absorbed only 0.99 wt% H2 and hardly underwent any hydrogen evolution under the same conditions. In addition, MgMgCNi3 composite showed outstanding cycling stability, with hydrogen absorption capacity retention rates reaching 98% after ten cycles at 623 K. The characterization analyses revealed that MgCNi3 and Mg formed Mg2NiH4 hydride and carbonaceous material during hydrogenation, where Mg2NiH4 induced dehydrogenation of MgH2 and carbon played a dispersive role during the composite reaction. Both features synergistically benefited the hydrogen storage properties of MgH2.