Synergistic effects of multiwalled carbon nanotubes and Al on the electrochemical hydrogen storage properties of Mg2Ni-type alloy prepared by mechanical alloying

► Al substitution for Mg in Mg2Ni leads to the formation of AlNi-type solid solution. ► MWCNTs addition hardly affects the phase compositions of milled alloys. ► MWCNTs addition decreases the particle sizes of Mg2Ni and Mg1.75Al0.25Ni. ► MWCNTs aggregate along the boundaries and surfaces of milled alloy particles. ► MWCNTs and Al show synergistic effects on electrochemical properties of Mg2Ni.