毕业论文（设计）--zr--based ab2 alloys for negative electrode of nickel--metal hydride battery论文.docVIP

Zr-Based AB2 Alloys for Negative Electrode of Nickel-Metal Hydride Battery A Dissertation Submitted for the Master Degree of Mechanical Engineering Author: Wang Guoliang Supervisor: Akiba Etsuo Abstract Ni-MH battery with high energy density and safety and without heavy metal pollution, is very important in current human society because of its widespread use in many fields such as vehicle and electronic product. In Ni-MH batteries, the positive electrode is usually fabricated by NiOOH; the negative electrode is comprised of different types of metal hydride materials. For practical application, the metal hydride materials have to fulfill some demands such as high hydrogen storage capacity, moderate equilibrium pressure, outstanding initial hydrogenation/dehydrogenation properties and so on. Zr-based Laves phase AB2 alloys with higher hydrogen storage capacity than those of AB5 and A2B7-type alloys, are considered as a group of the potential negative electrode materials for nickel-metal hydride Ni-MH batteries. However, Zr-based AB2 alloys confront with high H2 plateau pressure and poor initial hydrogenation properties which need to be solved before their commercial application. In this study, ZrMn2-based alloys comprised of different proportions of Zr, Ti, Ni, Mn and Al were employed to tune the hydrogen plateau pressure. The plateau pressures were successfully adjusted to the target pressure by substitution of Ni with Al in ZrMn2-based alloys. The plateau pressures of samples M03-M06 changed from 0.02 MPa to 0.08 MPa, M06 with the maximum hydrogen storage capacity of 1.38 wt.% exhibited lowest plateau pressure 0.02 MPa among all samples. Interestingly, the negative correlation between plateau pressure and unit cell volume of ZrMn2-based alloys was observed. Moreover, heat treatment and hot alkaline solution treatment were carried out in order to improve the initial activation properties of ZrMn2-based alloys. M01 and M02 were adopted for heat treatment stud