Microstructure And Electrochemical Properties Of Hydrogen Storage Alloys Ti_1.1-xFe_0.6Ni_0.3Zr_0.1Mn_0.2La_x（x=0,0.02,0.04,0.06,0.08）

The growing development of new energy vehicles has promoted the research process in the field of Ni/MH power battery.Among the various types of hydrogen storage alloys,Ti Fe hydrogen storage alloys stand out for their low cost and high hydrogen storage capacity,and gradually become one of the favored research objects of modern researchers.Taking Ti_1.1Fe_0.6Ni_0.3Zr_0.1Mn_0.2 based alloy as the research object,the first element substitution method is used to explore different La replace quantity of as-cast alloy microstructure,the effect of the electrochemical properties and electrochemical dynamics,results show that the alloy by Ti（Fe,Ni）and Zr Mn₂ two phase composition.Element substitution does not change the phase composition,La phase is distributed in clumps between two matrix phases,the series of alloys have excellent activation performance,the first charge can reach the maximum capacity,La substitution has a certain effect on improving the discharge capacity of the alloy.Ti_1.04Fe_0.6Ni_0.3Zr_0.1Mn_0.2La_0.06 has the maximum discharge capacity of 120.5 m Ah/g,compared with the base alloy 81.3 m Ah/g has large improvement,better retention capacity,dynamic performance with the ascension of La alternative content showed a trend of decline after rising first,When the substitution amount is 0.06,the high rate discharge performance of the alloy is the best,the limit current density（0.7462 A/g）and hydrogen diffusion coefficient(2.029×10^-10cm²/s)improve obviously,the electrochemical impedance value is minimal.On the optimal performance of as-cast alloy Ti_1.04Fe_0.6Ni_0.3Zr_0.1Mn_0.2La_0.06 mechanical ball milling processing,the purpose is to use high energy ball mill reduce grain size,improve chemical reaction rate.The electrochemical properties of the alloys were improved by different milling time（1h,5h,20h,30h）,but too long milling time did not bring positive benefits.Among them,the alloy with ball milling for 1h has the highest discharge capacity of 252.5 m Ah/g,but the capacity retention rate S₂₀ is only 42.4%.Kinetics tests show that the high rate discharge performance（HRD）of the alloy with ball milling for 1h is increased from 26.76%to 30.03%.The hydrogen diffusion coefficient(2.596×10^-10cm²/s)and the limiting current density（1.10 A/g）were increased to varying degrees,and the impedance value increased with the extension of ball milling time.Finally,Ni with good catalytic activity and electrical conductivity was used as additive and the optimal ball milling time（1 h）was selected to further improve the electrochemical and kinetic properties of the alloy.The results show that the alloy still has the crystal phase structure,but gradually appeared Fe Ni₃ phase,adding different Ni content（2%,5%,7%,10%）of the capacity and retention rate of the composite phase alloy have been greatly improved,10%Ni alloy first capacity up to 286.9 m Ah/g,S₂₀ 80.4%,nearly doubled.Moreover,the high rate discharge performance increases from 30.03%to 51.73%,and the changes of limit current density and electrochemical contact impedance confirm that Ni has excellent performance.