MgH2 and Ca(BH4)2 are potential thermal energy storage (TES) materials that possess extraordinarily high inherent thermal energy densities of up to 2 MJ/kg. However, the high desorption temperatures at atmospheric pressure [>300°C for Ca(BH4)2, >400°C for MgH2] coupled with slow kinetics represent significant challenges for their use in TES. In order to address these challenges, the present work focuses on the development of new modification approaches based on nanostructuring via high-energy vibratory ball milling and catalytic enhancement using pure Ni and Ni alloys. Our work reveals that high-energy vibrating-mill technique with ball-to-powder weight ratio as low as 13:1can produce MgH2 powders with nanocrystallites after 2h of milling. MgH2 milled with Ni (5 wt%) and Ni5Zr2 (5 wt%) catalysts for 2 h showed apparent activation energies, EA of 81 and 79 kJ/mol, respectively, corresponding to ∼50% decrease in EA and ∼100°C decrease in the decomposition temperature (Tdec). On the other hand, the decomposition reaction of Ca(BH4)2 does not seem to be catalyzed by the Ni-based catalysts tested.

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