气雾化低钴贮氢AB_5型合金的电化学性能和Rietveld分析

用快速凝固气体雾化法制备了低钴系列贮氢合金MlNi4 .3 -xCoxMn0 .4 Al0 .3 (x =0 75 ,0 45 ,0 2 9,0 1,Ml为富镧混合稀土 )并测试其电化学性能。气雾化法可显著提高贮氢合金电极的充 放电循环稳定性 ,x =0 45时合金的循环寿命与商用铸态合金的寿命相当。最大放电容量随着Co含量的增加 ,先增大后减小 ,在x=0 2 9时出现极大值 (30 4 4mAh/g)。结合循环寿命和最大放电容量两个性能指标 ,x =0 45时的合金具有良好的综合电化学性能。采用Rietveld法 (多晶衍射图形拟合法 )对其精细结构进行分析 ,合金仍保持母合金LaNi5的CaCu5型六方晶系结构 ,合金的晶胞体积对其循环寿命和最大放电容量起决定作用

Electrochemical Properties and Rietveld Analysis of Gas Atomized AB_5 Hydrogen Storage Alloys with Low Co Content

Hydrogen storage alloys MlNi 4.3- x Co x Mn 0.4 Al 0.3 ( x =0.75,0.45,0.29,0.1,Ml=mixed RE) with low content of Co were prepared by gas atomization(GA) and the electrochemical properties were measured. The results show that the charge discharge cycle stability of the alloys can be greatly improved by GA method. The crystal stability of the alloy MlNi 4.3- x Co x Mn 0.4 Al 0.3 with x =0.45 made by GA is equal to that of as cast alloy with x =0.75. As content of Co increases, the maximum discharge capacity of as atomized alloys increases firstly and then decreases, and reaches the maximum value 304 4 mAh/g at x =0.29. Summarily, the alloy with x =0.45 exhibits good stability and discharge capacity. The fine structure of the alloys were analyzed by the Rietveld method. It shows that the structure of the alloys is of CaCu 5 type, and the cycle stability and discharge capacity of the alloys depend on the crystal cell volume.