Mg0.9Ti0.1Ni1－xCox (x＝0.05, 0.1, 0.15, 0.2)合金的合成及电化学性能研究

采用机械合金化法合成了Mg_0.9Ti_0.1Ni_1－xCo_x (x＝0.05, 0.1, 0.15, 0.2)系列四元合金, 并对该系列合金的结构和电化学性能等方面进行了研究. 球磨100 h的该系列合金, XRD结果表明, X射线衍射峰均呈现宽化趋势, 基本呈非晶态. 充放电结果表明, 该系列合金具有较好的活化性能, 它们的循环稳定性明显好于MgNi合金, 其中Mg_0.9Ti_0.1Ni_0.8Co_0.2最大放电容量最高, 为427.5 mAh?g^－1. 在充放电循环过程中, Mg在合金表面形成了Mg(OH)₂是合金电极衰减的主要原因. 腐蚀曲线的测试结果表明, Co的添加可以提高合金电极在碱液中的抗腐蚀能力, 从而提高了电极的循环稳定性.

Preparation and Electrochemical Characteristics of Amorphous Mg0.9Ti0.1Ni1-xCox (x=0.05, 0.1,0.15, 0.2) Alloys

Mg-based hydrogen storage alloys Mg_0.9Ti_0.1Ni_1－xCo_x (x＝0.05, 0.1, 0.15, 0.2) were prepared by means of mechanical alloying, and the structure and the electrochemical characteristics of these Mg-based electrodes were also studied. The result of X-ray diffraction and transmission electron microscope showed that the main phase of the alloys had amorphous structures, and some trace of weak Ni peaks might co-exist. The charge-discharge cycle tests indicate that these alloys have good electrochemistry activation characteristics, and the cycle performance of these alloys were better than those of MgNi alloys. Among such alloys, the discharge capacity of Mg_0.9Ti_0.1Ni_0.8Co_0.2 was the highest, up to 427.5 mAh?g^－1. In the process of charge-discharge cycle test, the main reason of the electrode capacity decay is that Mg may become Mg(OH)₂ on the surface of alloys. The corrosion curve test indicates that the Co addition can improve the anticorrosion performance of these alloys in the alkali solution and the cycle stability of these alloy electrodes.