La_(1-x)Ce_xNi_5贮氢合金结构及活化特性

Structure and activation performance of La_(1-x)Ce_xNi_5 hydrogen storage alloy

研究稀土元素La和Ce以不同比例混合对贮氢合金La1-xCexNi5（x=0～1）的结构和活化特性的影响。采用X射线衍射仪分析不同Ce含量样品的结构，并用不添加任何粘结剂的粉末微电极技术及循环伏安方法考察贮氢合金的活化特性。结果表明：所制备的贮氢合金都是CaCu5单相结构；随着Ce含量的增加，晶胞参数α和晶胞体积明显减小，而晶胞参数c随Ce含量的变化略有增加。Ce的取代会降低合金在活化过程中的容量活化速度，但可以提高放电反应能力活化速度以及活化参数降低速度。同时还发现电势扫描速度对贮氢合金活化过程有显著影响。合金的容量活化速度和放电反应能力活化速度都随电势扫描速度降低而提高。

The effects of the ratio of rare earth metals Ce and La on the structure and the activation performance of La1-xCexNi5 （x= 0 - 1） hydrogen storage alloys were investigated. The structure of the alloys was analyzed by X-ray diffractrometry and the activation performance of the alloys was evaluated by CV with a cavity microelectrode which was featured without using any binding additives. The results show that all the hydrogen storage alloys have CaCu5 phase; both the cell parameter a and cell volume of the alloys decrease whereas the parameter c increases very slowly with the increase of Ce content. The substitution of Ce for La in the alloys results in the reduction of the capacity increase rate, the increase of the reaction capability increase rate, and the increase of the activation energy reduction rate during the activation process of the alloys. The effect of the potential scan rate on the activation performance was also studied. It is found that the capacity and the reaction capability increase when the scan rate decreases.