Analysis of the decomposition gases from α and β-Cd(BH₄)₂ synthesized by temperature controlled mechanical milling

We present a comprehensive study on the controlled phase synthesis and thermal decomposition of Cd(BH2)4, a material for solid state hydrogen storage obtained via the metathesis reaction of LiBH4 with CdCl2. By adjusting the stochiometry of the reactants and controlling the mechanical milling vial temperature, we have isolated the tetragonal (P42mn) low temperature phase and the cubic (View the MathML source) high temperature phase of the cadmium borohydride.

Cd(BH2)4 has a low thermodynamic stability and decomposes with fast kinetic at 348 K, when heated at 1 K min−1 against a backpressure of 1 bar H2. A semi-quantitative analysis reveals that the decomposition gases are composed of 1:1 H2 + B2H6 and that only Cd remains as solid crystalline phase.