The Investion On The Hydrogen Storage Performance Of The REMg₁₁Ni （RE=La, Ce, Pr, Nd; X=100,200）-type Alloys Prepared By Ball Milling

Along with excessive exploration and utilization of some non-renewabable resources such as coal, oil and gas, the energy crisis is more and more serious in today’s society, what’ more, environment pollution has seriously affect the human’s normal life, especially, the fog whether has brought on lots of inconvenience for human life which appears constantly in some cities recently. However, the chief culprits of the over pollution is due to excessive emission of the vehicle exhaust, the unreasonable development and utilization for coal and some other fuel resources. Therefore, in order to make up the increasingly dried up non-renewabale resource, the development of new energy is imminent. Among lots of energy, hydrogen energy stands out for its unique advantages as a clean energy. And it is always the focus of international scholars for the research of hydrogen storage and transporation. However, the hydrogen storage alloy is the best way for the storage of hydrogen. In the numerous hydrogen storage alloys, the Rare earth Mg-based hydrogen storage alloy attracts international scholar’s attention because of its unique advantages, such as high hydrogen absorption capacity, high discharge capacity, low cost and slight quality.The REMg11Ni (RE=La Ce Pr Nd) hydrogen storage alloys are prepared by induction melting method under the protection of He at the pressure of0.04Mpa which is under the condition of negative pressure in order to reduce the volatilization of RE and Mg. Then, the as-cast alloy is obtained, which is broken into power below75μm, and then mixed with x%(x=100200)Ni power for ball milling to obtain balling milled hydrogen storage. The maximum discharge capacity of the ball milled REMg11Ni (RE=La Ce Pr Nd) hydrogen storage with200%Ni power is1053.5、1040、1135.5、1079.8mAh/g, which are higher than the as-cast REMg11Ni (RE=La Ce Pr Nd) hydrogen storage alloys and ball milled with100%Ni power. In the aspect of hydrogen storage capacity, the milled alloys power with100%Ni power display excellent hydrogen absorption property and the hydrogen storage capacity is5.595、5.583、5.858、5.849wt%which is higher then the alloy power with 200%Ni power. What’s more, the maximum hydrogen absorption capacity decreases with the increasing of milling time except for CeMg11Ni hydrogen storage alloy and they can reach their maximum hydrogen absorption capacity for the first cycle. But for the as-cast alloys, they can get their maximum hydrogen absorption capacity for several absorb/desorb cycles for a long time, in addition to NdMg11Ni alloy which can not absorb hydrogen in30h, and the maximum hydrogen absorption capacity is4.576wt%、4.587wt%、3.371wt%for as-cast REMg11Ni (RE=La Ce Pr Nd) except NdMg11Ni alloy. As for the HRDs, the high rate discharge capacities decline gradually with the increasing of the discharge current density for all balling milled alloys. However, under the same discharge current density, the HRDs of the most alloys rise gradually with the rising of balling time.The alloys’ internal crystal structure can be changed by mechanical alloying, and the amorphous content increases together with the balling time increasing within a certain time. Finally, the phase compositions of the alloys are the mixture of amorphous and nanocrystalline. However, too much amorphous goes against to diffusion of hydrogen atom, which leads to the decline of hydrogen absorption capacity and hydrogen absorption rate. What’s more, the addition of Ni power could promote the formation of amorphous phase, and it could act as a catalyst for the increase of electrochemical property and hydrogen absorption/desorption performance. In addition, the tests of DSC and TG for LaMg11Ni+100%Ni alloys indicate that the stability of the hydride, decomposition temperature and the hydrogenation reaction activation energy decrease with the increasing of the ball milling time. At last, the experiment results show that hydrogenation reaction process can be promoted by mechanical alloying, which is favorable for the decomposition of hydride.