热碱处理对La-Mg-Ni系A_2B_7型储氢合金电极性能的影响  

Effect of Hot Alkaline Etching on Electrode Properties of La-Mg-Ni-based A_2B_7-type Hydrogen Storage Alloy

作　　者：曾书平[1] 罗永春[1,2] 李新宇[1] 康龙[1] 

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

出　　处：《中国稀土学报》2014年第6期701-709,共9页Journal of the Chinese Society of Rare Earths

基　　金：国家高技术863计划研究项目(2011AA03A408)资助

摘　　要：用真空感应熔炼和热处理制备了La0.64Gd0.2Mg0.16Ni3.1Co0.3Al0.1合金,利用SEM,EDS能谱分析、振动样品磁力计、XPS、ICP和电化学方法,研究了热碱处理时间（0-60 min）对合金颗粒表面的微观形貌、表面元素组成及状态、体相化学成分以及电化学性能的影响。研究表明：热碱处理使合金表面的Mg,Al,La和Ni元素发生不同程度的溶解析出或氧化,随处理时间增加,合金饱和磁化强度呈先增大后减小的趋势。当处理时间为15 min时,合金表面可形成较多的富Ni层,其饱和磁化强度达到最大值0.808 emu·g-1;当大于15 min时,随时间延长,富Ni层被氧化的倾向逐渐增大,同时表面形成稀土氧化物,导致合金饱和磁化强度逐渐减小。电化学性能测试表明：随热碱处理时间的增加,合金电极最大放电容量（Cmax）、循环稳定性（S100）及大电流放电特性（HRD900）均呈先增加后减小的规律。经15 min热碱处理的合金电极性能最佳,循环寿命S100由未处理时的83.67%提高到热碱处理后的93.09%。合金电极性能随热碱处理时间的变化规律与合金表面形成富镍层及其后续氧化倾向以及析出稀土氧化物关系密切。The Lao. 64 Gd0.2 Mg0.16 Ni3.1 Co0.3 Al0.1 alloy was prepared by vacuum induction melting and followed by heat treatment. The effects of hot alkaline treatment in different times （0 -60 min） were on the microstructure, and the surface elements and their state, and the bulk phase chemical components and the electrochemical proper- ties of alloy electrodes were studied by the means of SEM, EDS, VSM, XPS, ICP and electrochemical methods. The results showed that Mg, A1, La and Ni on the surface of alloy were dissolved or oxidized in different levels through the hot alkaline treatment. And with the increase of process time, the saturation magnetization intensity of alloy increased first and then decreased. When the process time was 15 min, the saturation magnetization intensitycould reach the maximum value of 0. 808 emu.g- 1, due to the formation of enriched element Ni layers on the sur- face of the alloy. When the process time was longer than 15 min, enriched Ni layers were oxidized and rare earth oxides formed on the surface increased gradually. That led to the gradual decrease of the saturation magnetization intensity of alloy. The electrochemical performance test showed that with the increase of the hot alkaline treatment time, the maximum discharge capacity（ Cmax ）, the cyclic stability （S100） and the high rate discharge （HRD900） of alloy electrodes increased first and then decreased, respectively. The alloy electrodes which was processed for 15 min had the best electrochemical performance, and its cyclic stability increased from 83.67% （blank） to 93.09% （treated）. The alloy electrodes performances which changed formation of enriched Ni layers and their subsequent oxidation ides on the alloy surface. with the hot alkali processing time was related to the tendency as well as the precipitation of rare earth ox-

关 键 词：热碱处理 稀土-镁-镍系A2B7型储氢合金 电化学性能 

分 类 号：TG139.7[一般工业技术—材料科学与工程] TG179[金属学及工艺—合金]