稀土氧化镱对La-Mg-Ni系A_2B_7型储氢合金电极性能的影响  

Effect of Ytterbium Oxide on Electrode Properties of La_(0.65)Gd_(0.2)Mg_(0.15)(NiCoAl)_(3.5) Hydrogen Storage Alloy

作　　者：田瑞珍[1] 罗永春[1,2] 高志杰[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》2012年第4期442-450,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：研究了分别添加纳米和微米级稀土氧化物Yb2O3(%,质量分数)后对La-Mg-Ni系A2B7型储氢合金电极电化学性能的影响。研究结果表明,添加Yb2O3能有效抑制合金电极表面La(OH)3和Mg(OH)2析出,随Yb2O3含量增加,La-Mg-Ni系A2B7型储氢合金电极的循环稳定性提高,但电极放电容量有所降低,电极动力学反应极化增加;Yb2O3粉末颗粒尺寸和团聚状态对合金电极性能影响比较明显,添加纳米级/微米级Yb2O3后均降低了合金电极放电容量,其中微米级Yb2O3对合金电极循环稳定性的改善效果更为明显。合金电极的循环稳定性与其放电过程的截止电位(-0.8～-0.6 V,相对Hg/HgO电极)有关,随截止电位减小,合金腐蚀倾向增加,电极循环寿命变差;Yb2O3在截止电位区间发生的电化学氧化-还原反应与储氢合金电极循环稳定性关系密切。The microsized and nanosized ytterbium oxides were added separately to A2 B7-type hydrogen storage alloys and their effects on electrode properties were investigated systematically.The results showed that ytterbium oxides additives suppressed the formation of La（OH）3 and Mg（OH）2 during charge/discharge process of alloy electrode and therefore the cyclic stability was improved.With the increase content of ytterbium oxides,the cyclic stability of alloy electrode was ameliorated,however,discharge capacity was reduced and reaction resistance was increased.The particle size and aggregating state of ytterbium oxides had significant effect on electrochemical properties of alloy electrode.The alloy electrodes with high dispersive microsized ytterbium oxides had better cyclic stability.The cut-off potential of alloy electrodes in discharge process as well as redox reaction of ytterbium oxides in alkali solution were both closely associated with cyclic stability of alloy electrodes.

关 键 词：稀土氧化物 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]