为了改善 La-Mg-Ni 系 A2 B7型电极合金的电化学循环稳定性,在合金中添加少量 Si。采用真空感应熔炼制备了 La0.8 Mg0.2 Ni3.3 Co0.2 Six (x=0~0.2)电极合金,并将部分合金在真空条件下,温度为900、950、1000和1050℃下进行了退火处理。用 XRD、SEM分析了铸态及退火态合金的微观结构,测试了铸态及快淬态合金的电化学循环稳定性。结果表明,铸态及快淬态合金均具有多相结构,包括两个主相(La, Mg)2 Ni7和 LaNi5及一个残余相 LaNi3。添加 Si 使LaNi5相增加而(La,Mg)2 Ni7相减少。合金的电化学循环稳定性随 Si 含量的增加而增加,当 Si 含量x从0增加到0.2时,铸态合金100次充放循环后的容量保持率(S100)从64.2%增加到73.1%,而950℃退火态合金的S100值从80.3%增加到93.7%。
In order to improve the cycle stability of the La-Mg-Ni-based A2 B7-type electrode alloy,a small amount of Si has been added to the alloy.The compositions of La0.8 Mg0.2 Ni3.3 Co0.2 Six (x=0-0.2)alloys were prepared by using a vacuum induction furnace,and a part of the alloys was annealed at 900,950,1000 and 1050℃ in vacuum.The microstructure of the as-cast and annealed alloys were examined by XRD and SEM, what’s more,the electrochemical cycle stability of the as-cast and quenched alloys has been checked out.The results indicated that the as-cast and quenched alloys had a multiphase structure,including two maj or phases of (La,Mg)2 Ni7 and LaNi5 as well as a residual phase of LaNi3 .The additive Si leaded to a increase in LaNi5 phase and a decrease in (La,Mg)2 Ni7 phase.Additionally,with the increase of Si content from 0 to 0.2,the capacity retention rate (S100 )of as-cast alloys enhanced from 64.2% to 73.1%,meanwhile,the capacity remaining rate (S100 )of the alloys quenched at 950℃ grew from 80.3% to 93.7%.
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