Structure and electrochemical hydrogen storage characteristics of nanocrystalline and amorphous MgNi-type alloy synthesized by mechanical milling

Both element substitution and surface modification were utilized to enhance the electrochemical performances of Mg-Ni-based alloys. Nanocrystalline and amorphous Mg1-xCexNi0.9Al0.1 (x = 0-0.08) + 50 wt.% Ni hydrogen storage alloys were synthesized through mechanical milling. The sample alloys show excellent activation property and have good electrochemical hydrogenation and dehydrogenation property at normal temperature. The discharge capacity has a peak value with Ce content varying which is 461.6 mAh/g for 10-h milled alloy, while that of Ce-0.04 alloy augments from 352.6 to 536.9 mAh/g with milling time extending from 5 to 30 h. Cycle stability is conspicuously improved with Ce content and milling duration augment. To be specific, when cycle number is fixed at 100, the capacity retention rate augments from 41% to 72% after Ce dosage rising from 0 to 0.08 for the 10-h milled alloy and from 58% to 76% after milling duration extending from 5 to 30 h for Ce-0.06 alloy. Additionally, the electrochemical kinetics of the alloys own peak values with Ce proportion varying; however, they always rise with milling duration extending.