Improved hydrogen desorption properties of magnesium hydride with TiFe0.8Mn0.2, graphite and iron addition

Abstract

The high dehydrogenation temperature of magnesium-based hydride (MgH2) is still a challenge as a potential hydrogen storage material in automobile applications. To improve the hydrogen desorption properties of MgH2; we selected TiFe0.8Mn0.2, graphite and Fe as additives. We prepared the Mg–graphite, Mg–TiFe0.8Mn0.2–Fe, Mg–TiFe0.8Mn0.2–graphite, Mg–Fe–graphite and Mg–TiFe0.8Mn0.2–Fe–graphite composites with high-energy ball milling under argon atmosphere. We investigated the effects of graphite and Fe addition to the desorption mechanism of TiFe0.8Mn0.2 using X-ray diffractometer (XRD), scanning electron microscope, differential scanning calorimeter and pressure-composition-temperature measurements using Sievert apparatus. We observed MgH2 in Mg–TiFe0.8Mn0.2–graphite, Mg–Fe–graphite and Mg–TiFe0.8Mn0.2–Fe–graphite with XRD analyses after hydrogenation at 200 °C under a hydrogen pressure of 2.5–2.6 MPa. As compared to pure milled MgH2 powder, we found that the dehydrogenation peak temperatures are decreased by 90, 160 and 165 °Cfor Mg–TiFe0.8Mn0.2–graphite, Mg–Fe–graphite, and Mg–TiFe0.8Mn0.2–Fe–graphite composites, respectively. The co-addition of TiFe0.8Mn0.2, graphite, and Fe exhibit the synergistic effects in improving the hydrogen desorption properties of MgH2.