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Keywords:

  • hydrogen storage;
  • metal hydride;
  • NaSc(BH4)4;
  • reaction thermodynamics;
  • density functional theory

Abstract

The double cation borohydride NaSc(BH4)4 has a total H2 content of 12.67 wt.% and has been suggested as a potential candidate for hydrogen storage applications. This study reports first-principles calculations of the structure and reaction thermodynamics of NaSc(BH4)4. The calculations indicate that NaSc(BH4)4 is decomposed into a mixture of ScB2, NaBH4, and Na2(B10H10) with H2 release of 9.3 wt.% at 118 K at a partial pressure of H2 of 100 bar. Reactant compositions that can destabilize NaSc(BH4)4 were evaluated. This effort identified four destabilization reactions that are predicted to have reaction thermodynamics for hydrogen release within the temperature range of 78–109 K. Even though the reactions conclusively produce undesired compounds, such as refractory materials or kinetically stable B12H12-containing species, the thermodynamic study suggests a direction for improving the thermodynamics of double cation borohydride-based systems being actively considered for hydrogen storage applications. © 2012 Wiley Periodicals, Inc.