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Abstract: In this study, activated carbon (AC) was added to the 2LiBH4–MgH2 composite and examined with respect to its effect on the hydrogen storage properties of the system. Our study found that AC is an effective additive for promoting the reversible dehydrogenation of the 2LiBH4–MgH2 composite. A series of control experiments were carried out to optimize the sample preparation method, milling time and addition amount of AC. In comparison with the neat LiBH4–MgH2 system, the LiBH4–MgH2–AC composite prepared under optimized conditions exhibits enhanced dehydrogenation kinetics, improved cyclic stability and particularly, eliminated incubation period between the two dehydrogenation stages. A combination of phase/microstructure/chemical state analyses has been conducted to gain insight into the promoting effect of AC on the reversible dehydrogenation of the 2LiBH4–MgH2 system. Our study found that AC exerts its promoting effect via tailoring nanophase structure of the 2LiBH4–MgH2 composite. [Copyright &y& Elsevier]

Abstract: In this paper, we report a novel method of improving the reversible dehydrogenation properties of the 2LiBH4–MgH2 composite. Our study found that mechanically milling with small amount of Al powder can markedly shorten or even eliminate the problematic incubation period that interrupts the dehydrogenation steps of the 2LiBH4–MgH2 composite. But the resulting composite showed serious kinetics degradation upon cycling. In an effort to solve this problem, we found that combined usage of small amounts of Al and MgO enabled the 2LiBH4–MgH2 composite to rapidly and reversibly deliver around 9 wt% hydrogen at 400 °C under 0.3 MPa H2, which compares favorably with the dehydrogenation performance of the composites with transition-metal additives. A combination of phase/microstructural analyses and series of control experiments has been conducted to gain insight into the promoting effects of Al and MgO. It was found that Al and MgO additives act as precursor and promoter for the formation of AlB2 heterogeneous nucleation sites, respectively. [Copyright &y& Elsevier]