Effects of substituting La with M(M=Sm, Nd, Pr) on electrochemical hydrogen storage characteristics of A_2B_7-type electrode alloys  

M(M=Sm,Nd,Pr)替代La对A_2B_7型贮氢合金电化学性能的影响(英文)

作　　者：张羊换[1,2] 李鹏欣 杨泰[2] 翟亭亭[2] 袁泽明[2] 郭世海[2] 

机构地区：[1]内蒙古科技大学内蒙古自治区白云鄂博矿多金属资源综合利用重点实验室,包头014010 [2]钢铁研究总院功能材料研究所,北京100081

出　　处：《Transactions of Nonferrous Metals Society of China》2014年第12期4012-4022,共11页中国有色金属学报（英文版）

基　　金：Projects(51161015,51371094)supported by the National Natural Science Foundations of China

摘　　要：The partial substitution of M （M=Sm, Nd, Pr） for La was performed in order to ameliorate the electrochemical hydrogen storage performance of RE–Mg–Ni-based A2B7-type electrode alloys. The La0.8–xMxMg0.2Ni3.35Al0.1Si0.05 （M=Sm, Nd, Pr;x=0-0.4） electrode alloys were fabricated by casting and annealing and their microstructures were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The major phases （La, Mg）2Ni7 with the hexagonal Ce2Ni7-type structure and LaNi5 with the hexagonal CaCu5-type structure make up the basic microstructure of the experimental alloys. The discharge capacities of the as-cast and annealed alloys all gain their maximum values with the M （M=Sm, Nd, Pr） content varying. The electrochemical cycle stability of the as-cast and annealed alloys clearly rises with the M （M=Sm, Nd, Pr） content growing. Furthermore, the electrochemical kinetics of the alloys, including the high rate discharge ability, charge transfer rate, limiting current density and hydrogen diffusion coefficient, all present a increase trend at first and then decrease with the rising of M （M=Sm, Nd, Pr） content.采用M(M=Sm,Nd,Pr)部分替代La,用合金熔炼及退火的方法制备La0.8–xMxMg0.2Ni3.35Al0.1Si0.05(M=Sm,Nd,Pr;x=0–0.4)电极合金,以提高RE–Mg–Ni系A2B7型贮氢合金的电化学性能。用X射线衍射(XRD)及扫描电子显微镜(SEM)分析合金的相组成和显微结构。结果表明,合金由六方结构Ce2Ni7型的(La,Mg)2Ni7相与六方结构Ca Cu5型的La Ni5相组成。随着M替换量的增加,铸态及退火态合金的放电容量均出现最大值。铸态及退火态合金的循环稳定性均随着M替换量的增加而增加。此外,合金的电化学动力学性能(包括高倍率放电性能、电荷传递速率、极限电流密度、氢扩散系数)均随着M替换量的增加呈现先上升后下降的趋势。

关 键 词：hydrogen storage elements substitution microstructure electrochemical performance 

分 类 号：TG139.7[一般工业技术—材料科学与工程]