【摘要】 以稀土贮氢合金Mm_xMl_1-xNi_3.55Co_0.75Mn_0.4Al_0.3（x= 0～0.5）为研究对象,通过调整两种混合稀土的比例来改变合金中La、Ce、Pr、Nd的含量,从而影响合金的相结构,分析合金相结构对电化学性能的影响规律。结果表明:所有合金的主相都为CaCu₅型结构的LaNi₅相,随x值的增加主相LaNi5的晶格常数a轴缩短,c轴变长,轴比增加,但晶胞体积不是线性递减的,在x=0.3时出现跳跃,晶胞体积较前后成分合金大;当x≥0.3时合金中出现AlLaNi4第二相,使得合金的放电能力减弱,但循环稳定性和高倍率放电能力却得到提高。综合比较,x=0.3时对应合金的综合电化学性能最好,合金具有较高的放电容量和充放电性能,放电电压平台较高,平台电压下放电持续时间较长。更多还原

【Abstract】 In this paper ,the rare earth based hydrogen storage alloys Ml1-xMmx(Ni3.55Co0.75Mn0.4Al0.3)(x=0～0.5)were investigated by adjusting Ml∶Mm ratio to change the content of La?Ce?Pr and Nd in the alloys and then change the phase structure. The influences on the electrochemical properties by phase structure were analyzed. The results indicate that the main phase of all alloys is LaNi5 with CaCu5 type structure and the crystal lattice parameters of LaNi5 are changed with the increasing of x value, i.e, decreased a-axis, increased c-axis and axial ratio and nonlinear decreased cell volume. The cell volume of alloy with x =0.3 is larger than the others. There is an amount of second phase AlLaNi4 in the alloys when x≥0.3, which decreases the discharge capacity, but increases the cycle stability and high rate discharge ability. By compared comprehensively, the alloy with x =0.3 shows a best electrochemical property, i.e, the higher discharge capacity and charge-discharge property, and maintain a long time at the flat voltage which is higher than the others.更多还原