Enhanced desorption and absorption properties of eutectic LiBH ₄-Ca(BH₄)₂ infiltrated into mesoporous carbon

We present enhanced hydrogen storage properties of the eutectic LiBH ₄-Ca(BH₄)₂ composite confined inside a mesoporous carbon scaffold via melt infiltration. The eutectic composition was examined by analyzing the enthalpy of fusion as a function of the LiBH ₄-to-Ca(BH₄)₂ ratio. Elemental analysis by energy dispersive X-ray spectroscopy and phase analysis by X-ray diffraction patterns provided both direct and indirect evidence for the infiltration of the LiBH₄-Ca(BH₄)₂ composite into the mesoporous channels of the carbon. The major dehydrogenation event occurred at ∼300°C, which is lower compared with the same composite without carbon or previously reported pure LiBH₄ confined in mesoporous carbons. Without additional catalytic additives, almost half of the initial hydrogen capacity was recovered after one cycling. This improved performance is a synergistic effect of the nanoconfinement and the mutual destabilization between LiBH₄ and Ca(BH₄)₂, and it also indicates that the eutectic melting phenomenon can be exploited as an effective way of coinfiltration of reactive hydride composites.