A2B7型La0.75Mg0.25Ni3.5-xFex(x=0～0.3)贮氢合金相结构及电化学性能研究  

Structure and Electrochemical Properties of A_2B_7 Type La_(0.75)Mg_(0.25)Ni_(3.5-x)Fe_x(x=0～0.3) Hydrogen Storage Alloys

作　　者：许剑轶[1,2] 阎汝煦[2] 罗永春[2] 张胤[1] 陈江平[2] 

机构地区：[1]内蒙古科技大学稀土学院,内蒙古包头014010 [2]兰州理工大学甘肃省有色金属新材料省部共建国家重点实验室,甘肃兰州730050

出　　处：《稀有金属》2009年第3期323-327,共5页Chinese Journal of Rare Metals

基　　金：国家自然科学基金项目(50171021)资助

摘　　要：采用感应熔炼方法制备了La_(0.75)Mg_(0.25)Ni_(3.5-x)Fe_x(x=0,0.05,0.1,0.2,0.3)四元贮氢合金,系统地研究了合金B侧Fe对Ni部分替代对合金相结构及电化学性能的影响。X射线衍射(XRD)分析表明,La_(0.75)Mg_(0.25)Ni_(3.5-x)Fe_x由(La,Mg)2Ni7相(包括Gd2Co7型高温相和Ce2Ni7型低温相)组成。此外,随着Fe元素的加入,该类合金中出现CaCu5型LaNi5相,且随着Fe含量的增加而增多。电化学测试表明,随Fe含量的增加,合金电极活化次数变化不大,而其最大放电容量呈现先增后减的趋势,合金的最大放电容量由x=0.05时的376.21mAh.g-1下降到x=0.3时的340.89mAh.g-1;合金的高倍率放电性能随着Fe含量的增加而降低,当电流密度为900mA.g-1时,合金的高倍率放电性能由83.66%(x=0)减小到62.23%(x=0.3);循环稳定性先增加后下降。The influence of substituting Fe for part of Ni in La0.75 Mg0.25Ni3.5 on the structure and electrochemical properties of thus formed La0.75 Mg0.25 Ni3.5-x Fex quaternary alloys （x = 0, 0.05, 0. 1 , 0. 2, 0. 3 ） was investigated. X-ray diffraction （ XRD ） analysis showed that the La0.75 Mg0.25 Ni3.5 was consisted of （LaMg）2Ni7 phase, LaNi5 phases of CaCu5 type appeared when Fe was added. The Rietveld analysis showed that the increase of Fe content led to an increase of LaNi5 content. It could be inferred that Fe element was helpful to the formation of LaNi5 phase. The electrochemical analysis showed that the substitutions led to some decrease in the maximum discharge capacity but little effect on the activation property. For the discharge current density of 900 mA·g^-1, the high rate discharge ability （HRD） of the alloy electrodes decreased from 83.66% （x =0） to 62.23% （x = 0.3）. The cyclic stability of alloy electrodes increased at first and then decreased with the increase of Fe content in alloys.

关 键 词：A2B7型贮氢合金 Fe替代 晶体结构 电化学性能 

分 类 号：TG146.4[一般工业技术—材料科学与工程]