Enhancing hydrogen storage performance of MgH2 through the addition of BaMnO3 synthesized via solid-state method

Abstract

Currently, magnesium hydride (MgH2) as a solid-state hydrogen storage material has become the subject of major research owing to its good reversibility, large hydrogen storage capacity (7.6 wt%) and affordability. However, MgH2 has a high decomposition temperature (>400 °C) and slow desorption and absorption kinetics. In this work, BaMnO3 was synthesized using the solid-state method and was used as an additive to overcome the drawbacks of MgH2. Interestingly, after adding 10 wt% of BaMnO3, the initial desorption temperature of MgH2 decreased to 282 °C, which was 138 °C lower than that of pure MgH2 and 61 °C lower than that of milled MgH2. For absorption kinetics, at 250 °C in 2 min, 10 wt% of BaMnO3-doped MgH2 absorbed 5.22 wt% of H2 compared to milled MgH2 (3.48 wt%). Conversely, the desorption kinetics also demonstrated that 10 wt% of BaMnO3-doped MgH2 samples desorbed 5.36 wt% of H2 at 300 °C within 1 h whereas milled MgH2 only released less than 0.32 wt% of H2. The activation energy was lowered by 45 kJ/mol compared to that of MgH2 after the addition of 10 wt% of BaMnO3. Further analyzed by using XRD revealed that the formation of Mg0·9Mn0·1O, Mn3O4 and Ba or Ba-containing enhanced the performance of MgH2.