摘要
为了改善La-Mg-Ni-Co系合金电极的循环稳定性,对铸态合金La0.75Mg0.25Ni3.5Co0.4在0.3MPa压力氩气保护下进行不同温度的退火(1123,1223和1323K),保温时间均为10h。研究了退火温度对合金的电化学性能的影响。X射线衍射(XRD)分析结果表明,铸态及1123K温度退火后合金主要由LaNi5,(La,Mg)2(Ni,Co)7相以及少量LaNi2相组成;退火温度为1223和1323K时,合金中LaNi2相消失,合金主要由LaNi5,(La,Mg)2(Ni,Co)7及(La,Mg)(Ni,Co)3相组成。随退火温度升高,最大放电容量从341.2mAh/g增加365.8mAh/g;循环稳定性得到改善,100次充放电循环后容量保持率从铸态合金的58.63%提高到1323K时的72.91%。
In order to improve the cycle stability of La-Mg-Ni-Co system alloy electrode, the as-cast La0.75Mg0.25Ni3.5Co0.4 alloy were annealed at 1123, 1223 and 1323 K for 10 hour in 0.3MPa argon atmosphere. The effects of annealing temperature on electrochemical performances of the alloy were investigated. The results analyzed by XRD show that the as-cast and annealed （1123 K） alloy has a multiphase structure including LaNi5 ,（La, Mg）2（Ni, Co）7 and a small amount of LaNi2 phases. Increcsing the annealing temperatures to 1223 and 1323K, the LaNi2 phase disappears,and the structure of the annealed alloy is composed of LaNi5, （La, Mg）2（Ni, Co）7 and （La, Mg）（Ni, Co）3 phases. With rising annealing temperature, the maximum discharge capacity of the alloy increases from 341.2 （as-cast） to 365.8mAh/g（1323K）, and the cycling stability of the alloy is improved,and the capacity retention rates of the alloy is enhanced from 58.63% （as-cast） to 72.91% （1323K）.
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2008年第1期16-19,共4页
Transactions of Materials and Heat Treatment
关键词
退火处理
La-Mg—Ni-Co系
贮氢合金
相结构
电化学性能
annealing treatment
La-Mg-Ni-Co system
hydrogen storage alloy
phase structure
electrochemical performance
