La-Mg-Ni基A_(5)B_(19)型La_(0.8-x)Nd_(x)Mg_(0.2)Ni_(3.8)层状超晶格负极材料结构及电化学性能  

Investigation of Structure and Electrochemical Properties of A5B19-Type La-Mg-Ni System Layered Superlattice Anode Materials in La_(0.8-x)Nd_(x)Mg_(0.2)Ni_(3.8)

作　　者：许剑轶[1] 张国芳[1] 可丹丹 赵鑫 胡峰[1] 蔡颖[1] Xu Jianyi;Zhang Guofang;Ke Dandan;Zhao Xin;Hu Feng;Cai Ying(School of Materials and Metallurgy,Inner Mongolia University of Science and Technology,Baotou 014010,China)

机构地区：[1]内蒙古科技大学材料与冶金学院,内蒙古包头014010

出　　处：《稀有金属》2024年第11期1653-1660,共8页Chinese Journal of Rare Metals

基　　金：国家自然科学基金项目(52061036);内蒙古自治区直属高校基础科研业务费资助项目(2023XKJX008,2023QNJS033);内蒙古自然科学基金项目(2022LHMS05021);内蒙古高校科技青年人才计划(NJYT23007);内蒙古科技大学创新基金项目(2019QDL-B07)资助

摘　　要：研究了退火态La_(0.8-x)Nd_(x)Mg_(0.2)Ni_(3..8)(x=0, 0.1, 0.2, 0.3)超晶格负极材料结构和电化学性能。结构分析表明,合金具有多相结构,x=0时样品由La Ni_(5)相和Ce_(5)Co_(19)(3R)型相组成,加入Nd后出现Pr_(5)Co_(19)(2H)型相,且丰度随着Nd增多而增加,而LaNi5相和Ce_(5)Co_(19)(3R)型相含量随之减少,Nd原子有利于A_(5)B_(19)相形成。此外,样品结构中各物相的晶胞体积呈线性减小。样品平衡压力-氢含量(P-C)等温曲线显示一个平台区域,Nd部分取代提高了样品平台压力,样品P-C等温曲线显示一个平台区域,Nd部分取代提高了样品平台压力,最大吸氢量与其电极电化学容量先增大而后减少,x=0.2时最大分别为0.953%(质量分数)和371.22 mAh·g^(-1)。样品电极活化性能没有变化,但是电极容量保持率首先从x=0时的70.70%增大到x=0.2时80.52%而后减少到x=0.3时的72.61%。Nd加入可显著提高电极高倍率放电性能(HRD),其改善是源于电极表面的电荷迁移反应和氢扩散反应共同作用的结果。In this paper,the structure and electrochemical characteristics of the annealed La_(0.8-x)Nd_(x)Mg_(0.2)Ni_(3.5)(x=0,0.1,0.2,0.3)layered super lattice negative electrodes were investigated.The samples was prepared via vacuum induction melting followed by annealing treatment at 1223 K for 12 h.The crystal structure analysis showed that all alloys were multiphase structures,x=0 alloy contained CaCu_(5)-type structures of LaNi5 phase,rhombohedral Ce_(5)Co_(19)-type(3R)structures of(La,Mg)5Ni19 phase(A_(5)B_(19) phase).After partial substitution of Nd for La,the hexagonal Pr_(5)Co_(19)-type(2H)structures of(La,Mg)5Ni19 phase appears,and the abundance of Pr_(5)Co_(19)-type phase increased from 10.76%(x=0.1)to 40.80%(x=0.3)while the abundance of CaCu_(5)-type phase and Ce_(5)Co_(19)-type phase decreased directly from 62.45%(x=0)to 35.69%(x=0.3)and from 37.55%(x=0)to 23.81%(x=0.3)as the Nd content increasing.The content of the A_(5)B_(19)-type phase(3R+2H)was the highest for x=0.3 and more than 50%.The results demonstrate that substituting La for Nd,that had a smaller atomic radius,improved the stability of the A_(5)B_(19)-type layer stacking structure phase and helped to generate A_(5)B_(19)-type phase.Furthermore,the unit cell volumes of various phases fall linearly with increasing x,as predicted by Vegard's equation,owing to the fact that Nd's atomic radius is less than that of La element.At a temperature of 298 K,the electrochemical P-C isotherms of La_(0.8-x)Nd_(x)Mg_(0.2)Ni_(3.5)(x=0,0.1,0.2,0.3)alloy electrodes were measured.Because the equilibrium pressures of LaNi5 phase and(La,Mg)5Ni19 phase were comparable,the sample electrodes display one plateau.The plateau pressure improved as the x increased for this collection of alloys,having the highest pressure in x=0.3.This was mostly due to the partial substitution of La by the smaller atomic radius Nd,which reduced the lattice properties of various phases,resulting in a larger pressure for the H atom to escape from the alloy.A higher plateau pressure also suggested

关 键 词：La-Mg-Ni系A_(5)B_(19)型超晶格负极材料 Nd替代 电化学特性 

分 类 号：TK91[动力工程及工程热物理]