La_(0.7)Pr_(0.15)Nd_(0.05)Mg_(0.3)Ni_(3.3-x)Co_(0.2)Al_(0.1)(Co_(0.75)Mn_(0.25))_x(x=0.0,0.2,0.4,0.6)的电化学性能研究  

Electrochemical Properties of La_(0.7)Pr_(0.15)Nd_(0.05)Mg_(0.3)Ni_(3.3-x)Co_(0.2)Al_(0.1)(Co_(0.75)Mn_(0.25))_x(x=0.0, 0.2, 0.4, 0.6) Alloys

作　　者：覃铭[1,2] 熊凯[1] 蓝志强[1] 刘奕新[1] 郭进[1] 

机构地区：[1]广西大学物理科学与工程技术学院,广西南宁530004 [2]百色学院物理与电子工程系,广西百色533000

出　　处：《中国稀土学报》2011年第3期351-359,共9页Journal of the Chinese Society of Rare Earths

基　　金：国家自然科学基金(50861003;51071054);广西大学有色金属及材料加工新技术教育部重点实验室开放基金(GXKFJ-09);百色学院科研项目(2010KB15;GBK2010008;GBK2010007)资助

摘　　要：在Ar气保护下用悬浮熔炼制备La0.7Pr0.15Nd0.05Mg0.3N i3.3-xCo0.2A l0.1(Co0.75Mn0.25)x(x=0.0,0.2,0.4,0.6)合金,系统研究了Co和Mn对合金储氢性能和电化学性能的影响。XRD相分析表明,合金相主要由(La,Pr)(N i,Co)5,LaMg2N i9,(La,Nd)2N i7和LaN i3相组成;添加Co和Mn后合金中(La,Pr)(N i,Co)5,(La,Nd)2N i7和LaN i3相晶胞体积增加,LaMg2N i9相晶胞体积变小。合金放氢PCT曲线测试表明,随着合金中Co和Mn含量的增加,合金吸氢量先减小后增加,放氢平台压下降,合金氢化物稳定性增加。合金电极电化学性能测试表明,添加Co和Mn使合金电极放电容量减小,容量保持率S100从53.2%(x=0.0)增加到63.0%(x=0.6),合金电极的电循环稳定性增强,高倍率放电性能HRD1500先增加后减小。此外,合金电极的极化电阻先减小后增加,交换电流密度、循环伏安特性阳极峰电流密度和极限电流密度先增加后减小,合金内氢原子扩散系数先增加后减小,表明添加适量的Co和Mn可以提高合金电极的电化学动力学性能。La0.7Pr0.15Nd0.05Mg0.3N i3.3-xCo0.2A l0.1（Co0.75Mn0.25）x（x= 0.0,0.2,0.4,0.6） alloys were prepared by magnetic levitation melting underAr atmosphere.The effects ofCo andMn on the hydrogen storage properties and electrochem ical characteristics were stud ied systematically.The XRD results showed that the alloy phase was mainly composed of（La,Pr）（N i,Co）5,LaMg2N i9,（La,Nd）2N i7and LaN i3 phase.W ith the add ition of Co and Mn,the cell vol-umes of（La,Pr）（N i,Co）5,（La,Nd）2N i7and LaN i3 phase increased and that of the LaMg2N i9phase de-creased.The PCT desorption curves showed that with the increase of Co and Mn content,the hydrogen stor-age capacity of the alloys decreased first then in-creased,the desorption equilibrium pressure de-creased approximately and the hydride stability in-creased.The electrochem ical measurements ind icatedthatwith the add ition ofCo andMn,the d ischarge ca-pacities of the alloy electrodes decreased,while the cycle stability of the alloy electrode was improved,and the d ischarge capacity retention ratio after 100 charge-d ischarge cycles increased from 53.2%（x=0.0） to 63.0%（x=0.6）,whereas the high rate d ischarge-ability（HRD） increased first then decreased.The electrochem ical kinetics analysis showed that the d iffu-sion coefficient of hydrogen,the exchange current density,the cyclic voltammogram and the lim iting cur-rent density first increased then decreased with the in-creasing of Co and Mn content,while the polarization resistance of the alloy electrodes first decreased then increased,which ind icated that the electrochem ical kinetics of the alloy electrodes was improved with proper add ition of Co and Mn.

关 键 词：储氢合金 PCT性能 电化学性能 稀土 

分 类 号：TG139.7[一般工业技术—材料科学与工程]