Electrochemical Hydrogen Storage Performance of the Nanocrystalline and Amorphous Pr-Mg-Ni-based Alloys Synthesized by Mechanical Milling

The PrMg12-type composite alloy of PrMg11Ni + x wt% Ni (x = 100, 200) with an amorphous and nanocrystalline microstructure were synthesized through the mechanical milling. Effects of milling duration and Ni content on the microstructures and electrochemical hydrogen storage performances of the ball-milled alloys were methodically studied. The ball-milled alloys obtain the optimum discharge capacities at the first cycle. Increasing Ni content dramatically enhances the electrochemical property of alloys. Milling time varying may obviously impact the electrochemical performance of these alloys. The discharge capacities show a significant upward trend with milling duration prolonging, but milling for a longer time more than 40 h induces a slight decrease in the discharge capacity of the x = 200 alloy. As milling duration increases, the cycle stability clearly lowers, while it first declines and then augments under the same condition for the x = 200 alloy. The high-rate discharge abilities of the ball-milled alloys show the optimum values with milling time varying.