【摘要】 为了改善La0.75Mg0.25Ni3.5Cox(x=0,0.6)合金电极的循环稳定性,对铸态合金在0.3MPa压力氩气保护下进行不同温度退火(1123、1223和1323K),保温时间均为10h。研究了退火温度对合金电化学性能的影响。X射线衍射(XRD)和扫描电镜(SEM)分析表明,铸态及1123K温度退火后合金主要由LaNi5、(La,Mg)2Ni7相及少量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)Ni3及(La,Mg)2Ni7相组成。电化学试验结果表明,随着退火温度增加,x=0及x=0.6的合金最大放电容量分别从铸态的343.7、319.2增加到1323K时的390.4、357.5mAh/g;同时退火改善合金的循环稳定性,100次充放电循环后,随着退火温度升高,x=0、0.6时合金的容量保持率(S100)分别从铸态的55.17%、58.22%增加到1323K时的76.66%、67.58%。更多还原

【Abstract】 In order to improve the cycle stability of La0.75Mg0.25Ni3.5Cox(x=0,0.6) system alloy electrode,the as-cast alloy were annealed treatment at 1123,1223 and 1323K for 10h in 0.3MPa argon atmosphere.The effects of annealing temperature on the electrochemical performances of the alloys were investigated.The results analyzed by XRD and SEM show that the as-cast and annealed(1123K) alloys have the LaNi5,(La,Mg)2Ni7 and a small amount of the LaNi2 phases.When the annealing temperatures are 1223 and 1323K,the LaNi2 phase disappears,the structures of the annealed alloys are composed of the LaNi5,(La,Mg)Ni3 and(La,Mg)2Ni7 phases.According to electrochemical measure,with the rising annealing temperature,the maximum discharge capacities of the x=0 and x=0.6 alloys increase from 343.7,319.2(as-cast) to 390.4,357.5mAh/g(1323K) respectively.Annealing treatment improves the cycling stabilities of the alloys,the capacity retention rates of the x=0 and x=0.6 alloys(S100) enhance from 55.17%,58.22% to 76.66%,67.58% (1323K) with the increasing temperature after 100 cycles,respectively.更多还原