摘要
在 AB5型混合稀土 -镍系贮氢多元合金的研究中 ,为设计高性能价廉的 AB5型贮氢电极合金 ,人们对其 B侧多元合金化和 A( =RE)侧稀土组元分别进行了系统地研究。本工作通过对 RE( Ni Co Mn Ti) 5合金中稀土组元 ( RE=MlβMm1-β)进行组合优化研究 ,主要还是依赖于市售的混合稀土金属 ( Ml和 Mm)原材料 ,利用不同种类的混合稀土中 La,Ce,Nd和 Pr组元相应变化 ,来调整其稀土成分。结果表明 ,Ml∶Mm比例对其电化学性能有显著影响。 Ml0 .85Mm0 .15( Ni Co Mn Ti) 5对应合金具有最高放电容量为 2 80 m A· h/g和较好的循环寿命 ,而合金电化学性能与相应的结构有关。因此 ,采用 Rietveld法对其精细结构分析具有重要意义。分析表明 ,合金仍保持母体合金 La Ni5和 Ca Cu5型六方晶系结构 ,空间群为 P6/mmm;合金中 La,Ce,Nd,Pr( 1a) - Ni,Co,Mn,Ti( 2 c)键长对电化学容量起决定作用。
In the development of hydrogen storage alloys for Ni-MH battery,multicomponent AB 5 type of mischmetal nickel based hydrogen storage alloys were mostly investigated not only on B side of nickel and nickel substitute element,i.e.,multicomponent alloying of B side,but also on A(RE) side (RE=La 1-x-y-z Ce xNd yPr z) with different La,Ce,Nd and Pr compositions in order to optimize the hydride electrode alloy. Results showed that La,Ce,Nd and Pr had great effects on the electrode performance.Due to the high price of pure La,Ce,Nd and Pr,the REB 5 type electrode material for mass production should not be by pure rare earths,The use of unrefined rare earth mixture (mischmetal-a mixture of different composition of Lanthanum,cerium,neodymium,preseodymium,etc) was very economical. Generally,they are categorized as lanthanum rich mischmetal (denoted as Ml),cerium rich mischmetal (denoted as Mm) and highlanthanum mischmetal (denoted as Lm,etc) owing to different mineral resources and extractive metallurgical methods.Therefore,good electrochemical properties of RENi 5 alloys could be obtained by choosing a proper Mm:Ml ratio. In this paper,the electrochemical properties Ml βMm 1 β (NiCoMnTi) 5 hydrogen storage alloys with different composition of rare earth components were systematically examined.By the optimization of the Ml:Mm ratio, the alloy Ml 0.85 Mm 0.15 (NiCoMnTi) 5 showed a maximum capacity 280 mA hg 1 and good cycling stability.The basic structure of Ml βMm 1 β (NiCoMnTi) 5 revealed by the Rietveld refinement analysis method,is found to be the same as that of LaNi 5 (CaCu 5: space groups P6/mmm). The bond length of La、Ce、Nd、Pr(1a)—Ni、Co、Mn、Ti(2c) is the key factor that determines the electrochemical capacity.
出处
《功能材料》
EI
CAS
CSCD
北大核心
1998年第1期38-41,共4页
Journal of Functional Materials
基金
"863"资助项目
关键词
贮氢合金
稀土
Rierveld分析
电化学性能
Hydrogen storage alloy
Rietveld refinement analysis
rare earth
electrochemical property
