Hydrogen storage properties of Mg[BH₄]₂

Matsunaga, Tomoya; Buchter, Florian; Mauron, Phillipe; Bielmann, Michael; Nakamori, Y.; Orimo, S.; Ohba, N.; Miwa, K.; Towata, S.; Züttel, Andreas

doi:10.1016/j.jallcom.2007.05.054

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Journal article

Hydrogen storage properties of Mg[BH₄]₂

Matsunaga, Tomoya EMPA, Department Environment, Energy and Mobility, Abt. 138 “Hydrogen & Energy”, Dübendorf, Switzerland - University of Fribourg, Physics Department, Switzerland
Buchter, Florian EMPA, Department Environment, Energy and Mobility, Abt. 138 “Hydrogen & Energy”, Dübendorf, Switzerland - University of Fribourg, Physics Department, Switzerland
Mauron, Phillipe EMPA, Department Environment, Energy and Mobility, Abt. 138 “Hydrogen & Energy”, Dübendorf, Switzerland - University of Fribourg, Physics Department, Switzerland
Bielmann, Michael EMPA, Department Environment, Energy and Mobility, Abt. 138 “Hydrogen & Energy”, Dübendorf, Switzerland - University of Fribourg, Physics Department, Switzerland
Nakamori, Y. Institute for Materials Research, Tohoku University, Sendai Japan
Orimo, S. Institute for Materials Research, Tohoku University, Sendai Japan
Ohba, N. Toyota Central Research and Development Laboratories, Inc., Nagakute, Aichi, Japan
Miwa, K. Toyota Central Research and Development Laboratories, Inc., Nagakute, Aichi, Japan
Towata, S. Toyota Central Research and Development Laboratories, Inc., Nagakute, Aichi, Japan
Züttel, Andreas EMPA, Department Environment, Energy and Mobility, Abt. 138 “Hydrogen & Energy”, Dübendorf, Switzerland - University of Fribourg, Physics Department, Switzerland

18.05.2007

Published in:

Journal of Alloys and Compounds. - 2008, vol. 259, no. 1-2, p. 583-588

English Among the large variety of possible complex hydrides only few exhibit a large gravimetric hydrogen density and stability around 40 kJ mol⁻¹H₂. Mg[BH₄]₂ is based on theoretical approaches a complex hydride with an equilibrium hydrogen pressure of approximately 1 bar at room temperature and a hydrogen content of 14.9 mass%. The reaction of Li[BH₄] with MgCl₂ at elevated temperatures was investigated as a possible route to synthesize Mg[BH₄]₂. Li[BH₄] reacts with MgCl₂ at a temperature >523 K at a pressure of 10 MPa of hydrogen, where the product contains LiCl and Mg[BH₄]₂. The desorption pc-isotherm of the product obtained at 623 K shows two flat plateaus, which indicates that the decomposition of the product consists of a two-step reaction. The products of the first and the second decomposition reaction were analyzed by means of X-ray diffraction and found to be MgH₂ and Mg, respectively. The enthalpy for the first decomposition reaction was determined to be ΔH = −39.3 kJ mol⁻¹H₂ by the Van’t Hoff plot of the equilibrium measurements between 563 K and 623 K, which is significantly lower than that for pure Li[BH₄] (ΔH = −74.9 kJ mol⁻¹H₂). However, only the second reaction step (MgH₂ → Mg) is reversible at the condition up to 623 K at 10 MPa of hydrogen.

Faculty

Faculté des sciences et de médecine

Department

Département de Physique

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