Enhanced hydrogen sorption capacities and kinetics of Mg2Ni alloys by ball-milling with carbon and Pd coating

Solid-state hydrogen storage alloys are becoming a practical method to transport and utilize hydrogen as fuel for various technologies. In this paper, the kinetics and capacity of hydrogen desorption from Mg-based alloys have markedly been enhanced by tuning the surface composition of alloy particles. Mg2Ni-C-t,C-x composites (where t refers to the pregrinding time and x to the Brunauer-Emmet-Teller specific surface area) were prepared by ball-milling the alloy in the presence of preground graphite, and Pd-coated Mg2Ni alloy powders were obtained by controlled chemical deposition of Pd on the alloy surface. We have found that the optimization of the pregrinding step of carbon is a determinant factor in enhancing the hydrogen desorption capacity of the Mg2Ni-10 Wt.% C-10,C-320 composites to 2.6 wt.% at 150 degreesC, the maximum performance so far reported on desorption for Mg-based alloys. Such value can even be raised to 2.8 wt.% by applying Pd deposition on the composite.