A_2B_7型La_(0.64)Gd_(0.2)Mg_(0.16(1+x))Ni_(3.1)Co_(0.3)Al_(0.1)储氢合金微观组织和电化学性能  

Microstructure and Electrochemical Properties of A_2B_7-Type La_(0.64)Gd_(0.2)Mg_(0.16(1+x))Ni_(3.1)Co_(0.3)Al_(0.1) Hydrogen Storage Alloys

作　　者：王可[1] 罗永春[2,1] 梅兴志 张国庆[2] 康龙[2] 

机构地区：[1]兰州理工大学有色金属先进加工与再利用省部共建国家重点实验室,甘肃兰州730050 [2]兰州理工大学材料科学与工程学院,甘肃兰州730050

出　　处：《稀有金属》2015年第10期882-890,共9页Chinese Journal of Rare Metals

基　　金：国家科技部'863'计划项目(2011AA03A408)资助

摘　　要：以综合电化学性能较佳的低镁含量合金La0.64Gd0.2Mg0.16Ni3.1Co0.3Al0.1为基础,通过改变Mg元素含量的添加方式,用感应熔炼方法与热处理制备了La0.64Gd0.2Mg0.16（1＋x）Ni3.1Co0.3Al0.1系列合金,系统研究了该条件下镁元素成分波动（Mg过量值x）对La-Mg-Ni系A2B7型合金微观结构和电化学性能的影响规律。合金相结构分析表明,合金退火组织由主相Ce2Ni7（Gd2Co7）型以及Pr5Co19型、Pu Ni3型和Ca Cu5型多相组成,随Mg过量值x增加,合金中主相Ce2Ni7型相丰度呈现先增加后减小的趋势;当Mg过量值0〈x≤50%时,合金组织的Ce2Ni7型主相相丰度达到81.04%~87.18%;x=0,80%时,Ce2Ni7型主相丰度减小至76.3%以下。电化学测试结果表明,随Mg过量值x增加,合金电极最大放电容量呈先增加后降低趋势,x=10%时合金具有最高电化学放电容量（384.6 m Ah·g-1）;当Mg过量值x在5%~50%范围内变化时,其电极循环稳定性均保持在S100≥90%,此时镁元素成分波动变化对合金电极循环稳定性的影响不敏感。合金电极的高倍率放电性能（HRD）随Mg过量值的增加呈先增大后减小趋势,其中电极表面的电荷转移速率是影响合金电化学反应动力学性能的主要控制步骤。La0 64 Gd0.2 Mg0.16（l ＋x）Ni3. I Co0.3 A10.1 alloys with low magnesium content and excellent integrated electrochemical properties were prepared by induction melting and heat treatment. By changing the addition way of magnesium content, the effects of magnesium composition fluctuations （Mg excess value x） on the microstructure and electrochemical properties of A2B7-type La-Mg-Ni alloys were systematically investigated. The phase structure results showed that the annealing organization of alloys was multiphase structure and mainly consisted of Ce2 Ni7 （ Gd2 Co7 ） -type, Pr5 Col9-type, PuNi3 -type and CaCu5 -type phases. The main phase abundance of Ce2 Ni7 （Gd2Co7 ）-type phase was 81.04% to 87. 18% with the value of 0 〈x~〈50%. The main phase abundance of CezNiT-type phase first in- creased then decreased with the increase of Mg excess value x. The phase abundance of Ce2Ni7-type phase decreased below 76.3% for x =0 and 80%. The electrochemical measurements results showed that the maximum discharge capacity of alloy electrodes first increased and then decreased, and the alloy electrode exhibited the maximum electrochemical discharge capacity （384.6 mAh .g -1^ ） when x = 10%. After 100 charge-discharge cycles, the discharge capacity retention rate $10o were both maintained more than 90% with the value of Mg excess in the range of 5%-50%. Now the influence of magnesium composition fluctuations on the cycling stability of alloy electrodes was insensitive. The high rate discharge ability of alloy electrodes first showed a increasing then a decreasing trend with the increase of Mg ex- cess value. The influence of charge transfer rate of the electrode surface on electrochemical kinetics property was the main control step.

关 键 词：R-Mg-Ni系A2B7型储氢合金 Mg元素 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]