Improved Dehydrogenation and Rehydrogenation Properties of LiBH4 by Nanosized Ni Addition

The complex hydride LiBH4, with a hydrogen density of 18.5 mass%, has been attracting significant interests for hydrogen storage, while suffers from its high dehydrogenation and rehydrogenation temperature. In this work, we systematically investigated the improvement effects of nanosized Ni on the dehydrogenation and rehydrogenation reactions of LiBH4 using thermogravimetry, quadrupole mass spectrometry and pressure-composition-isotherm analyses. Nanosized Ni was homogeneously dispersed on the surface of LiBH4 after ball milling. The dehydrogenation peak temperature of LiBH4 was reduced from 743 to 696 K with addition of 25 mass% Ni. First, LiBH4 tended to react with Ni to form Ni4B3, which suggests the thermodynamic destabilization effect of Ni. Then, the in-situ formed Ni4B3 was suggested to play a catalytic role on the dehydrogenation of the unreacted LiBH4. Moreover, the rehydrogenation content of LiBH4 was improved from 4.3 to 10.8 mass% by addition of 25 mass% Ni, suggesting the significant improvement effect of Ni4B3 on the rehydrogenation.