Improved Dehydrogenation and Rehydrogenation Properties of LiBH₄ by Nanosized Ni Addition

Abstract

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.