稀土元素R对储氢合金(LaRMg)(NiCoAlZn)_(3.5)相结构和电化学性能的影响  

Influence of rare-earth elements R on phase-structure and electrochemical properties of hydrogen storage alloys(LaRMg)(NiCoAlZn)_(3.5)

作　　者：罗永春[1] 贾秋荣[1] 吴婷[1] 康龙[1] 

机构地区：[1]兰州理工大学甘肃省有色金属新材料重点实验室,甘肃兰州730050

出　　处：《兰州理工大学学报》2009年第4期1-6,共6页Journal of Lanzhou University of Technology

基　　金：国家自然科学基金(50171021)

摘　　要：以(LaRMg)(NiCoAlZn)3.5(R=La、Ce、Pr、Nd、Gd、Y和Sc)合金为研究对象,研究稀土元素R部分替代La后对合金相结构和相组成及电化学性能的影响.XRD和EPMA方法分析结果表明,合金(LaRMg)(NiCoAlZn)3.5退火组织主要由Ce2Ni7型相(或Gd2Co7型)、PuNi3型相和CaCu5型相组成;Ce、Pr和Nd元素的替代对合金相组成没有明显影响,而Gd元素替代使合金中CaCu5型相明显减少,Ce2Ni7型(或Gd2Co7型)相显著增加,其相丰度达到79.03%;Y和Sc元素替代时合金中Gd2Co7型相基本消失.电化学测试和分析表明,稀土元素R替代La后对合金电极活化性能影响不大,其中Nd、Gd、Y和Sc部分替代La在一定程度上提高合金的最大放电容量,而Gd元素替代时合金电极容量最高达到343.1 mAh/g;Gd和Nd元素部分替代La使合金电极的循环稳定性得到明显提高,S100分别达到95.3%和93.0%.此外,Sc部分替代La能有效改善合金电极的高倍率放电性能.Taking alloys（LaRMg）（NiCoAlZn）3.5 as objects of investigation,the influence of rare-earth R（La,Ce,Pr,Nd,Gd,Y and Sc） substituted for partial La on the phase-structure and electrochemical properties was investigated.XRD analysis and EPMA showed that the annealing structure of （LaRMg）（NiCoAlZn）3.5 consisted mainly of CaCu5-type phase,Ce2Ni7（or Gd2Co7-type） and PuNi3-type phase.The substitution of elements Ce,Pr and Nd had no significant influence on the phase-structure of the alloys.However,CaCu5-type phase decreased and Ce2Ni7-type phase increased obviously with the substitution of Gd, the Ce2Ni7- type phase abundance reaching 79. 03%. Meanwhile, the substitution of elements Y and Sc led basically to disappearance of Gd2Co7-type phase. The electrochemical measurements and analysis showed that the activation performance of the alloys was not influenced much, but the maximum discharge capacity was improved to a certain extent by thesubstitution of elements Nd, Gd, Y, and So. Substitution of element Gd made the electrode capacity of alloys amount to its maximum as 343.1 mAh/g, and the substitution of Nd and Gd improved remarkably the cyclic stability of the alloyed electrode, their S100 reaching 93. 0% and 95.1%, respectively. Besides, the alloy of Sc substitution improved effectively the high rate discharge ability of the alloys.

关 键 词：稀土-Mg-Ni基储氢合金 微观组织 电化学性能 

分 类 号：TG146.4[一般工业技术—材料科学与工程]