Investigation On The Phase Structure And Hydrogen Storage Characteristics Of Ball-milled Mg_x Ni_100-x (x=70,60,50) Composite Hydrogen Storage Material

Recently,Mg-based hydrogen storage haven been regarded as the one of the most promising hydrogen storage because of high hydrogen storage capacity, abundant resources , light weight and low price.Mg2Ni is one of the most promising due to its relatively high capacity(3.8wt%) and high theoretical discharge capacity(999 mAh/g),However,the reaction of magnesium alloys with hydrogen requires quite high temperature and pressures. This thesis intends to get a kind of hydrogen storage electrode alloy with great synthetical properties through optimizing the composition and right ball-milling.In this thesis,the microstructure and electrochemical properties of amorphous MgxNi100-x(x=70,60,50)+ywt%TiF3(y=0,1,3),MgxNi100-x(x=70,60,50)+ywt%TiO2(y=0,1,3,5),Mg50Ni50+ywt%Ti(y=0,1,3,5)composites of ball-milling was investigated. The structure and morphology were observed and analyzed by XRD and SEM. The influence of the alloy composition and preparation technology on the amorphous phase was analyzed. Hydrogen absorption capacity was measured by P-C-T curve tester. By mean of electrochemical measurements technology, such as electrochemical impedance spectrum (EIS), potentiodynamic polarization, open-circuit potential. the investigation results have theoretical understanding and helpful guides to explain the better electrochemical performances and attain its utilization. the obtained results are as follows:The microstructures and electrochemical performances of ball-milling alloys were synthetically investigated. The investigation shows that hydrogen storage alloy can be achieved a good activation performance and high storage capacity by ball-milling and with the ball milling time increases, the storage capacity also increase. at the same time,the more the ball-milling time, the more amorphous quantity. its electrochemical capacity drops quickly for the reason of oxidation in the lye and oxidation which lead to the formation of Mg(OH)2. catalyst of TiF3,TiO2 and Ti in favour of the hydrogen storage characteristics of MgxNi100-x(x=70,60,50)alloys partly.but the content of catalyst is not the more ,the better.it should be controled 5wt%. The hydrogen storage characteristics of the Mg50Ni50+ywt%Ti(y=0,1,3,5) alloys first increase and then the decrease with the increase of Ti content . which ascribe to increase of amount of the TiNi2 phase with increasing Ti content. With the decreases of Mg content. The dynamic characteristic of the MgxNi100-x+3wt%TiF3 (x=70,60,50) alloys electrodes were investigated.The influence of the Mg element content and ball-milling technology were explain from the dynamic.The high-rate dischargeability of the alloys decreases with the rising Mg content. With the decreases of Mg content, some kinetics parameters increase, involving the excharge current density, limit current density, cyclic voltammetry discharge capacity, and the open-circuit potential get negative shift and corrosion resistance deterioration.