摘要
用Pr、Nd、Y、Sm和Gd按一定比例组成混合稀土对La进行部分替代,通过分别增加混合稀土中各元素的含量获得5种合金试样(分别用Pr0.6、Nd0.6、Y0.6、Sm0.6和Gd0.6表示),研究了混合稀土组成对A2B7型La_(0.63)(Pr,Nd,Y,Sm,Gd)_(0.2)Mg_(0.17)Ni_(3.1)Co_(0.3)Al_(0.1)退火合金微观结构与电化学性能的影响规律。合金相结构分析表明,合金微观组织均由主相2H-Ce2Ni7型和CaCu5型第二相组成,其中Y0.6合金的Ce2Ni7型相丰度最高(93.3%(质量分数))。合金中Ce2Ni7型和CaCu5型相晶胞体积均随A端元素平均原子半径的减小而逐渐降低。电化学分析表明,合金放氢平台压力为0.013~0.054 MPa,最大储氢量(Hmax/M)为1.23%~1.42%(质量分数),其中Y0.6合金具有最高的电化学放电容量(404.4 mAh/g)和最佳的容量保持率(S100=93.50%);合金电极高倍率放电性能HRD按试样Gd0.6、Sm0.6、Y0.6、Nd0.6、Pr0.6顺序依次减小。混合稀土中适量增加Y元素可显著提高和改善合金电极的综合电化学性能。
La was partially substituted by the mixed rare earth composed of Pr,Nd?Y?Sm,Gd?and the five al-loys in which the content of each rare earth element,in the mixed rare earth was respectively increased were re-presented by Pr06,Nd〇6.Y〇.6.Sm06and Cd〇6.The effect of mixed rare earth on the structure and electrochem-ical properties of the annealed alloys T(Pr,Nd,Y,Sm,Gd)0,2Mg(U7Ni3.iCo(h3Al(u were systematically in gated.Phase structure analysis showed that the annealed alloys mainly consisted of CegNiyand CaCus-type phase,the maximum phase abundance of Ce2Ni7-type was93.3%for Y06alloy.The unit cell volume of Ce2Ni7type and CaCu5type phases decreased with the increasing average atomic radius of A side elements.Electro-chemical studies indicated that the hydrogen desorption pressure of the alloys were rang of0.013-0.054MPa and hydrogen storage capacity(Hmnx/M)reached1.23%-42wt.o,when alloy YO.6electrode exhibited the maxi-mum discharge capacity(404.4mAh/g)and the best cyclic stability(8100=93.5%).The high rate discharge a-bility(HRD)of the alloy electrodes decreased as the sequence of Gd06,Sm06,Y06,Pr06,Nd06.The appropriateincrease of Y content in the mixed rare earth can significantly improve the overall electrochemical properties ofthe alloy electrodes.
作者
杨阳
罗永春
梅兴志
王浩
邓安强
YANG Yang;LUO Yongchun;MEI Xingzhi;WANG Hao;DEN Anqiang(School of Materials Science and Engineering, Lanzhou University of Technology, Lanzhou 730050,China;State Key Laboratory of Advanced Processing and Recycling of Nonferrous Metals,Lanzhou University of Technology, Lanzhou 730050, China)
出处
《功能材料》
EI
CAS
CSCD
北大核心
2017年第8期135-141,共7页
Journal of Functional Materials
基金
国家高技术研究发展计划(863计划)资助项目(2011AA03A408)
关键词
稀土-镁-镍系A2B7型储氢合金
混合稀土元素影响
相结构
电化学性能
A2B7-type rare earth-Mg-Ni hydrogen storage alloys
the mixed rare earth effect
microstructure
electrochemical properties