La_(0.63)Gd_(0.2)Mg_(0.17)Ni_(3.2-x)Co_(0.3)Al_x(x=0～0.4)储氢合金的微观组织和电化学性能  

Microstructure and Properties of La_(0.63)Gd_(0.2)Mg_(0.17)Ni_(3.2-x)Co_(0.3)Al_x(x=0～0.4) Hydrogen Storage Alloys

作　　者：罗永春[1,2] 吴婷[1] 高志杰[1] 李嵘峰[1] 林振[1] 康龙[1] 

机构地区：[1]兰州理工大学材料科学及工程学院,甘肃兰州730050 [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：《中国稀土学报》2010年第3期347-354,共8页Journal of the Chinese Society of Rare Earths

基　　金：国家自然科学专项基金资助项目(50941019)

摘　　要：采用真空感应熔炼方法制备了La0.83Mg0.17Ni3.1Co0.3Al0.1和La0.63Gd0.2Mg0.17Ni3.2-xCo0.3Alx（x=0~0.4）贮氢合金,并在氩气气氛900℃进行退火处理。通过X射线衍射（XRD）、显微电子探针（EPMA）分析方法和电化学测试分析研究了Gd和Al元素对合金微观组织和电化学性能的影响。研究结果表明,该系列合金退火组织主要由Ce2Ni7/Gd2Co7型、Pr5Co19型、PuNi3型和CaCu5型相组成;Gd元素的加入使合金中CaCu5型相明显减少,Ce2Ni7型/Gd2Co7型相显著增加,x=0.1时其相丰度达到81.2%;随Al含量x不断增加,合金中CaCu5型相丰度逐渐增多,当x=0.1~0.2时,CaCu5型相丰度为4%~5%,x=0.4时,其相丰度达到66.65%。电化学测试分析表明,Gd和Al元素对合金电极活化性能影响不大,当x=0.1时,含Gd合金电极放电容量达到最大值391 mAh.g-1,随Al含量x进一步增加,合金电极放电容量降低。含Gd和加入适量的Al元素可使合金电极循环稳定性得到明显提高,当Al含量x=0.1,0.2时,经100次充放电循环后其电极容量保持率S100分别为93.7%和90.1%,其中La0.63Gd0.2Mg0.17Ni3.1Co0.3Al0.1合金具有最好的综合电化学性能。La0.83Mg0.17Ni3.1Co0.3Al0.1 and La0.63Gd0.2Mg0.17Ni3.2-xCo0.3Alx（x=0~0.4） hydrogen storage alloys were prepared by induction melting followed by an annealing treatment at 900 ℃ in Ar.The effects of Gd and Al on the microstructure and electrochemical properties of the alloys were investigated by means of X-ray diffraction（XRD）,electron probe micro-analysis（EPMA） and electrochemical measurements.The results showed that all these alloys mainly consisted of Ce2Ni7-type/Gd2Co7-type,Pr5Co19-type,PuNi3-type and CaCu5-type phases.The substitution of La by Gd led to a significant decrease in CaCu5-type phase abundance and an increase in Ce2Ni7-type phase abundance.Meanwhile,the increase of Al could obviously change the microstructure,and the CaCu5-type phase abundance was about 4%~5% when x was from 0.1 to 0.2,however,CaCu5-type phase abundance reached 66.65% when x was 0.4.The electrochemical measurements showed that all these alloys had good activation performance,but the discharge capacity of the alloys decreased with the increase of Al.The discharge capacity of the alloys reached 391 mAh·g-1 when x was 0.1.The cyclic stability of the La0.63Gd0.2Mg0.17Ni3.2-xCo0.3Alx alloy electrodes were improved obviously.After 100 charge-discharge cycles,the discharge capacity retention rate S100=（C100/Cmax） of the alloy electrodes（x=0.1,0.2） reached to 93.7% and 90.1%,respectively.Among the alloys studied,the La0.63Gd0.2Mg0.17Ni3.1Co0.3Al0.1 alloy possessed the best over electrochemical properties.

关 键 词：La-Mg-Ni系A2B7型储氢合金 微观组织 电化学性能 合金化 稀土 

分 类 号：O643[理学—物理化学] TG139[理学—化学]