Effects Of Doped Carbon Nanotubes And Al₂O₃ On The Electrochemical Properties Of Mg₂Ni Hydrogen Storage Alloys

The Mg₂Ni hydrogen storage alloy is a very potential hydrogen storage material because of it's large theoretical storage capacity and good charging performance.Mg₂Ni hydrogen storage alloy is an ideal material for the negative electrode of nickel-hydrogen battery.Previous studies have shown that doping Al₂O₃can effectively improve the electrochemical hydrogen storage performance of Mg₂Ni alloy.Al₂O₃ is an additive with improved hydrogen storage performance of metal hydride.In order to improve the electrochemical performance,an attempt was made to dope Carbon Nanotubes?CNTs?in Mg₂Ni alloy.CNTs have received extensive attention due to their large hydrogen storage capacity,rapid hydrogen release rate,and ability to release hydrogen at normal temperature.By studying doped CNTs and two materials co-doped in Mg₂Ni alloy,this paper finds a new method to improve the electrochemical hydrogen storage performance of Mg₂Ni alloy,and a series of valuable research results were obtained:?1?The doping different content of CNTs in the Mg₂Ni hydrogen storage alloy was carried out by ball milling.It is find that the carbon nanotube-doped Mg₂Ni hydrogen storage alloy has a significant increase in the maximum discharge capacity and a high capacity retention rate.Among them,when the doping ratio is 15wt.%,the electrochemical performance of the alloy is the most obvious,the maximum discharge capacity is the largest,which is 224.1 mAh/g,the discharge platform is the most gradual,and the charge retention rate of self-discharge is as high as 99.2%.?2?In the electrode sheets of Mg₂Ni+15wt.%CNTs at 5 h,15 h and 25 h after ball milling,the maximum discharge capacity of ball milling for 5 h is the highest,the discharge capacity is the strongest,and the capacity retention rate of self-discharge is the highest,and the comprehensive electrochemical performance is highter.?3?X-ray diffraction?XRD?and scanning electron microscopy?SEM?analysis of the sample showed that the Mg₂Ni+15wt.%CNTs alloy particles became smaller as the ball milling time increased,and the ball milling time continued to increase,resulting in agglomeration of the alloy particles.?4?Different alloys of Al₂O₃ were doped in the above alloy Mg₂Ni+15wt.%CNTs.With the increase of Al₂O₃ content,the maximum discharge capacity first increased and then decreased.When the Al₂O₃ content was 1wt.%,the maximum discharge is 231.8 mAh/g.