Dehydriding and rehydriding processes of well-crystallized Mg(BH4)2 accompanying with formation of intermediate compounds

H. W. Li, K. Kikuchi, Y. Nakamori, N. Ohba, K. Miwa, S. Towata, S. Orimo

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Abstract

Dehydriding and rehydriding properties of well-crystallized Mg(BH4)2 were systematically investigated by thermogravimetry (TG) and pressure-composition-temperature (PCT) measurements. The dehydriding reaction of Mg(BH4)2 starts at approximately 500 K, and about 14.4 mass% of hydrogen is desorbed according to the following multi-step reaction:Mg(BH4)2 → some intermediate compounds → MgH2 + 2B + 3H2 → Mg + 2B + 4H2The apparent enthalpy change in the dehydriding reaction from Mg(BH4)2 to MgH2 is estimated to be 57 ± 5 kJ mol-1 H2 based on the result of the PCT measurement. It is proved that approximately 6.1 mass% of hydrogen can be reversibly stored for the sample of Mg(BH4)2 after the dehydriding reaction, through the formation of a possible intermediate compound such as MgB12H12.

Original languageEnglish
Pages (from-to)1342-1347
Number of pages6
JournalActa Materialia
Volume56
Issue number6
DOIs
Publication statusPublished - Apr 1 2008
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Ceramics and Composites
  • Polymers and Plastics
  • Metals and Alloys

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