(西安交通大学 金属材料强度国家重点实验室, 西安 710049)
摘 要: 通过X射线衍射、 扫描电镜和能谱分析了新型低钴储氢合金La1-xCaxNi3.2Co0.3Al0.3(0≤x≤0.4)合金的晶体结构、 组织形貌及各相化学成分， 并研究了该合金的电化学性能。结果表明： 当x≤0.1时， 合金基本保持LaNi5主相和LaNi3第二相；当0.1＜x≤0.3时，出现的Al(NiCo)3第二相替代了LaNi3第二相。随着Ca含量的增加， 合金活化性能变差， 当x＝0.2时， 放电容量达到最高值（为295mA·h/g）， 合金经300次充放电后， 循环容量保持率为82.5%， 且循环寿命得以改善。
关键字: 储氢合金； 放电容量； 循环稳定性
La1-xCaxNi3.2Co0.3Al0.3(0≤x≤0.4) low-cobalt hydrogen storage alloys
（State Key Laboratory for Mechanical Behavior of Materials,
Xi'an Jiaotong University, Xi'an 710049, China）
Abstract: The crystal characteristics, microstructure and chemical composition of the new-type low-cobalt hydrogen storage alloys La1-xCaxNi3.2Co0.3Al0.3(0≤x≤0.4) were analyzed by X-ray diffractrometry, scanning electron microscopy and EDX, and the electrochemical properties of the alloys were investigated. The results show that the prepared alloys are basically composed of LaNi5 as matrix phase and LaNi3 as second phase when x≤0.1. When 0.1＜x≤0.3, the second phase LaNi3 is substituted by a new phase Al(NiCo)3. The activity of alloys become bad with the increase of Ca content. When x=0.2, the discharge capacity reaches the highest value of 295 mA·h/g, and the capacity of the alloys can hold 82.5% after 300 charge/discharge cycles.
Key words: hydrogen storage alloy; discharge capacity; cycle stability
