Direct observation of ion exchange in mechanically activated LiH + MgB 2 system using ultrahigh field nuclear magnetic resonance spectroscopy

The LiBH 4 + MgH 2 system has great potential for hydrogen vehicle applications. In this study, the reported solid-state hydrogenation system made of LiH + 1 / 2 MgB 2 has been investigated using ultrahigh field nuclear magnetic resonance spectroscopy. It is found that Mg-Li ion exchange occurs within MgB 2 during ball milling to form a compound of ( Mg 1 − x Li 2 x ) B 2 , which facilitates the formation of LiBH 4 in the subsequent hydriding reaction. This discovery offers a scientific foundation for investigating the detailed mechanisms of solid-state hydrogenation and dehydrogenation of the LiBH 4 + MgH 2 system in the future.