Metal magnesium based hydride

K Yvon, B. BertheviUe, Magnesium based ternary metal hydrides containing alkali and alkaline-earth elements, J. Alloys Compd. 425 (2006) 101-108. 

Key words hydrogen storage/nanostructured light metal-based hydrides/controlled reactive mechanical alloying/magnesium hydride/amorphous hydrides... 

Intensive development of NiMH battery technology is underway in many places worldwide. Widespread activity has been reported on magnesium-based metal hydride alloys for capacity and cost advantages, evaluation of bipolar NiMH designs, satellite NiMH battery development, and a myriad of technical goals too lengthy to list here. However, the most intensive NiMH development at this time involves efforts to raise specific power to new levels and to reduce cost. 

Treatment of indole (pKa - 17) with strong bases such as butyl lithium, Grignard reagents, or metal hydrides produces the corresponding indolyl anion, which reacts with electrophiles either on nitrogen or at the C3 position. With lithium, sodium, or potassium as counterion the indolyl anion tends to react on nitrogen, as in the preparation of 7.35. However, with magnesium as the counterion the intermediate has an essentially covalent rather than ionic structure, and reaction tends to occur at the C3 position, as in the preparation of 7.36. 

Up to now, research on ternary metal hydrides based on magnesium and alkaline or alkaline earth metals has not produced alloys with practical hydrogen storage characteristics [250]. However, study of quaternary alloys is a new fleld that is worth investigating and could give practical hydrogen storage systems [250]. 

Application of SPD techniques to metal hydrides is a new field of research. Skripnyuk and Rabin were the first to use ECAP to improve the hydrogen storage properties of Mg-based alloys [254, 255]. The first study on ECAP-processed magnesium alloy ZK90 showed an improvement in sorption kinetics without loss of hydrogen capacity or change in thermodynamic parameters [254]. figure 4.12 shows comparable results for the Mg-Ni eutectic alloy [255]. 

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