Fabrication And Electrochemical Properties Of Low-cost Ti-V-based Alloys For Negative Electrode Materials Of Nickel-metal Hydride Batteries

In recent years, with the increasing awareness of the national resource protection and the substantial reduction of domestic reserves of rare earth resources, the price of rare earth metals has increased a lot. As a result, the cost of main raw materials of rare earth metals of commercial AB5hydrogen storage alloys for the negative electrode materials of Ni/metal hydride secondary batteries also rise. Based on an overview of the development of various hydrogen storage alloys at home and on abroad, and the previous research work in our group, this thesis amis to prepare Ti-V-based hydrogen storage electrode alloys by using commercial V-Fe alloy instead of pure metal V, which is commonly used in the fabrication of Ti-V-based hydrogen storage electrode alloys. The structure and electrochemical properties of the Ti-V-based hydrogen storage electrode alloys are studied by XRD, SEM, constant current charge and discharge, electrochemical impedance spectroscopy, linear polarization and electrochemical anodic polarization and so on. The relationships among the composition, structure and electrochemical properties of the alloys are also discussed. As V-Fe alloy is much cheap than pure metal V, the present Ti-V based alloys are low cost, which are potentially valuable for commercial applications in hydrogen storage electrode alloys.The study of the structure and electrochemical properties of the (Tio.95Zro.o5)((80FeV#)0.533Mn0.12Cr0.1Ni0.24)x (x=2.0-5.5) alloys shows that with the increase of stoichiometric ratio of x, the cycle stability of the alloys decreases with the increase of x, however, maximum discharge capacities increases.With the increase of the Ni content, the maximum discharge capacity of (Ti0.95Zr0.05)((80FeV#)0.583Mn0.12Cr0.1Nix)2.5(x=0.24-0.40) alloys decreases but the cycle stability improves with the increase of Ni content.The activation performance of (Ti1-xZrx)((80FeV#)0.533Mn0.15Ni0.35)3.0(x=0.30-0.50) alloys is excellent. The maximum discharge capacity of the alloy electrode first increases and then decreases with the increasing substitution of Zr for Ti. The cycle stability of the alloys increase with the increasing substitution of Zr for Ti, but the high-rate dischargeability of the alloys is dimaged.