非晶态Ti_3Ni_2合金在NiMH电池中的电化学性能

Electrochemical Properties of the Amorphous Ti3Ni2 Alloy in Ni/MH Batteries
Cao Xinxin, Ma Liqun, Yang Meng, Zhao Xiangyu, Ding Yi
Nanjing University of Technology, Nanjing 210009, China
Rare Metal Materials and Engineering Volume 41, Issue 9, September 2012 Online English edition of the Chinese language journal Cite this article as: Rare Metal Materials and Engineering, 2012, 41(9): 15phous Ti3Ni2 (Ti2Ni/TiNi) alloy has been prepared by mechanical milling of crystalline Ti3Ni2 alloy, and its electrochemical properties were investigated. The results of charge and discharge test show that the amorphous Ti3Ni2 alloy can resolve the problem of extremely short cycle life of crystalline Ti3Ni2 alloy at high temperature (333 K). The capacity retention rate of amorphous Ti3Ni2 alloy is greatly increased to 88.83% at 333 K compared with the retention rate of its crystalline counterpart 39.47% after 19 cycles. Based on analysis of Tafel polarization, linear polarization, and electrochemical impedance spectroscopy, it is found that the major reason for the improvement is the presence of amorphous Ti3Ni2 alloy, which has much better corrosion resistance compared with its crystalline counterpart. Key words: hydrogen storage alloy; Ti3Ni2 alloy; amorphous; electrochemical properties; Ni/MH battery
Nickel/metal hydride (Ni/MH) secondary batteries, which are the most successful applications for hydrogen storage alloys, have been extensively studied[1–4]. Various Ti-based metal hydride electrodes, such as Ti-Fe-based, Ti-Mn-based and Ti-V-based alloys have been used as hydrogen storage materials of the work electrode of nickel-metal hydride battery, and investigated for decades[5-7]. Ti-Ni-based alloys have attracted much attention because of their relatively low cost and low density, and have shown great potential for electrochemical hydrogen storage[8-13]. According to the binary phase diagram of Ti-Ni, there are three intermetallic phases of Ti-Ni alloys: Ti2Ni, TiNi, and TiNi3. Only Ti2Ni and TiNi alloys can absorb/desorb hydrogen at room temperature. TiNi has the advantage of long cycle life, but its maximum discharge capacity is only 150 mAh/g at the low discharge current density of 30 mA/g [10]. Although Ti2Ni has high maximum discharge capacity, it suffers from severe capacity loss during charge-discharge cycling, which restrict its application.[12] Wakao S. et al.[13] studied the discharging capacities and the corrosion resistance of TiNix (x=0.5-1). With increasing of the value of x, the TiNix electrode has worse discharge ability, but better capacity retention due to better corrosion resistance.