Microstructure And Electrochemical Properties Of Ti-Fe Based Hydrogen Storage Alloys

The rapid development of new energy vehicles has promoted the exploration of nickel-hydrogen power batteries.Among many practical hydrogen storage alloys,Ti-Fe-based hydrogen storage alloys are typical representatives of AB-type hydrogen storage alloys,which can not only participate in gaseous hydrogenation reactions,but also expand the development of power batteries through electrochemical reactions.It is currently the main research object in the field of hydrogen storage alloys.The master alloy studied in this paper is Ti_1.1Fe_0.6Ni_0.3Zr_0.1Mn_0.2.The effect of different Sm substitutions on the microstructure,electrochemical performance and electrochemical kinetics of as-cast alloys was investigated by elemental substitution method.The results show that the element substitution method has an effect on the discharge capacity of the alloy.The highest discharge capacity of each component alloy is Ti_1.06Fe_0.6Ni_0.3Zr_0.1Mn_0.2Sm_0.04,which is 180.2 mAh/g higher the 122.3 mAh/g of the master alloy.And the kinetic performance of the alloy increases first and then decreases with the increase of the Sm substitution amount,and the high-rate discharge performance and the limiting current density?-0.717 A/g?and hydrogen diffusion coefficient(8.63×10^-11 cm²/s)of the alloy with the substitution amount of 0.04 have obviously improved.In this paper,mechanical ball milling is used to modify the as-cast alloy.The particle size of the alloy particles is obviously reduced by the ball milling method,and obvious amorphous and nanocrystalline structures appear;the ball milling time has a great change on the discharge capacity of the alloy electrode,and the highest discharge capacity is the ball-milled alloy for 30 h,reached 207.3 mAh/g and the capacity retention rate(S₂₀)was 68.3%,indicating that the corrosion resistance of the ball milled alloy was improved.The kinetics results showed that at a discharge current density of 60 mA/g,the high-rate discharge performance?HRD?of the ball-milled 30 h alloy increased from 40.4% to 61.6%,and the hydrogen diffusion coefficient was 8.92×10^-11cm²/s.The current density increased from0.245 A/g to 0.602 A/g.The use of Ni holding well corrosion resistance and electrocatalytic activity as an additive improves the electrochemical performance of the alloy.The results show that the alloy still has obvious amorphous and nanocrystalline structure after Ni ball milling,and the agglomeration phenomenon is obvious.The addition of Ni ball milling makes the discharge performance of the composite alloy higher,and the cycle stability batter.The maximum discharge capacity of the alloy with Ni ball milling for 30 h is increased to 239.8 mAh/g,and the lifting effect is the most obvious.After calculation,the exchange current density I₀of the alloy milled for 30 h is increased from 0.53 A/g to 2.37 A/g.