摘要
根据合金化原理，从合金相结构的角度，探讨合金优化时相结构对电极性能如放电容量和循环寿命等方面的影响。具有ｈＰ６－ＣａＣｕ５型结构的单相ＬａＮｉ５存在一个大的均相区，并为吸氢提供大量的四面体和八面体间隙位置。快凝下非化学计量ＡＢ５＋ｘ贮氢合金，由于过剩Ｂ原子的插入而产生各向异性变形晶体点阵也即ａ轴减小ｃ轴增加。经退火后变形晶体点阵得以弛予形成双相合金。面心立方ＮｉＣＯ３和六方的ＭｏＣＯ３相有利于电极综合性能的提高。对于富稀土混合稀土贮氢合金，ＭｍＮｉ（Ｍｍ：混合稀土）相在晶界择优沉淀，抗氧化能力降低；而贫稀土的合金ＡｌＮｉ３在晶界择优沉淀，大大地降低放电容量和循环寿命。原位Ｘ射线衍射方法是研究气相吸放氢等温过程及原位相结构点阵膨胀的有效方法。
According to the alloying principle,the influence of phase structure with the optimization of alloy composition on the electrode properties,such as discharge capacity and cyclic life,has been reviewed.A single phase LaNi5 with hP6CaCu5 type structure has a large homogeneous region and a lot of tetrahedral and octahedral lattice defects for hydrogen absorption.Nonstoichiometry AB5+x materials prepared under the rapid solidification produced the anisotropic crystal lattices,i.e.decreased aaxis and increased caxis,resulting from the excess of Belements incorporated in the hP6CaCu5 type structure.After annealing,the deformed crystal lattice can be relaxed to form the doublephase alloy.Facecentered cubic NiCO3 and hexagonal MoCO3 were found to be beneficial to the electrode properties.For the Mmrich alloy [Mmx(NiCoMnAl)5],MmNi phase precipitated at the grain boundaries was less resistant to the oxidation.For the Mmdeficient alloy (AlNi3),AlNi3 phase precipitated at grain boundaries caused a significant decrease in capacity and the cycle life.XRD analysis is well adapted to gas phase absorptiondesorption isotherms and the lattice expansion in situ.
出处
《电源技术》
EI
CAS
CSCD
北大核心
1998年第3期107-110,138,共5页
Chinese Journal of Power Sources
基金
国家自然科学基金
关键词
稀土贮氢合金
相结构
放电
碱性蓄电池
rareearth based hydrogen storage alloy,phase structure,discharge capacity,cycle life
