Intermediate compound comprising [B12H12] 2- anion formed in the dehydrogenation is regarded to be responsible for the degradation of reversibility of metal borohydrides, whereas little is known about the formation of Li2B12H12 in the LiBH4-MgH2 combined system. In this study, we investigated the dehydrogenation process of the LiBH4-MgH2 system in a heating run under different hydrogen pressures. Our experimental results demonstrated, for the first time, that Li2B12H 12 was formed under hydrogen pressure ≤1.0 MPa, but not formed under 2.0 MPa. Moreover, the formation of Li2B12H 12 was found to negatively depending on the hydrogen pressure, and also influence subsequent formation of MgB2: the more Li 2B12H12 that formed, the less MgB2 obtained. These findings indicate that suppression of the formation of intermediate compound Li2B12H12, such as by using adequate hydrogen pressures (e.g., 2.0 MPa), is of great importance for further improvement of hydrogen storage properties of the LiBH 4-MgH2 system.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Surfaces, Coatings and Films
- Physical and Theoretical Chemistry