Effects Of Ball-milling Process And Catalyst On The Phase Structure And Hydrogen Storage Properties Of La–mg System Hydrogen Storage Composite Alloys

The Effects of ball-milling time and CeO₂ addition on microstructure,hydrogen absorption and electrochemical of ball-milled La₂Mg_17+xwt.%Ni(x=50,100,150,200) composites were investigated.. The study includes the followings: (1) The effects of Ni amounts on microstructure,hydrogen absorption and eleetrochemical properties of ball-milled La₂Mg₁₇ composites; (2) The effects of ball-milling time and CeO₂ addition on microstructure and hydrogen absorption properties of La₂Mg_17+50wt.%Ni composites ; (3) The effects of ball-milled and CeO₂ addition on the microstructure and eleetrochemical properties of La₂Mg_17+200wt.%Ni composites.The influence of Ni amounts on the microstrueture and electrochemical properties of 60h ball-milled La₂Mg₁₇ composites revealed that certain amount of Ni can change the phase structure of the alloy to achieve the amorphous alloy. Hydrogen absorbing rate tests found that add 50wt.% Ni can form a Mg2Ni new phase compare with other Ni content alloys. This is La₂Mg_17+50wt.%Ni composites hydrogen absorbing rate and hydrogen absorbing quantity higher than other Ni content composite alloy reasons. The completely amorphous structure La₂Mg_{17+ 200wt.%}Ni composites with CeO₂ displayed a good electrochemical perform- ance.Effects of CeO₂ addition on microstructures and hydrogen absorbing properties of La₂Mg_{17+50 wt.%}Ni composites were investigated. The hydrogen absorbing properties increased with the prolonging of ball-milling time without or with CeO₂. Hydrogen absorption capacity of La₂Mg_{17+50 wt.%}Ni composites with ball-milling 100h was the best of all the group which was 3.569 wt.% and the hydrogen absorbing rate was 98.91% in 2 minutes. Hydrogen absorption capacity of La₂Mg_{17+50 wt.%}Ni composites with CeO₂ higher than without CeO₂.Effects of CeO₂ addition on microstructures and electrochemical properties of La₂Mg₁₇ +200wt.%Ni composites were investigated.The discharge capacity of the La₂Mg_17+200wt.% composites ball-milled with and without CeO₂ for different time were 353.1 mAh/g,326.9 mAh/g,352.1 mAh/g,352.6 mAh/g,390.9 mAh/g,373.5 mAh/g,398.8 mAh/g and 409.8mAh/g. with CeO₂ higher than that without CeO₂. But CeO₂ addition has little effect on the cycling stability. cycling retention rate of individual samples even can be decrease, this may be join CeO₂ increases the alloy samples of defects and specific surface area, increased the alloy contact with alkali solution, to accelerate the corrosion process of alloys.