快淬对La-Mg-Ni系A_2B_7型电极合金循环稳定性的影响

用熔体快淬工艺制备了La-Mg-Ni系A2B7型La0.75-xZrxMg0.25Ni3.2Co0.2Al0.1（x=0,0.05,0.1,0.15,0.2）电极合金。用XRD、SEM、TEM分析了铸态及快淬态合金的微观结构,用程控电池测试设备测试了铸态及快淬态合金电极的电化学循环稳定性,研究了快淬工艺对合金结构及电化学循环稳定性的影响,探讨了电极合金的失效机理。结果表明,快淬态合金均具有多相结构,包括两个主相（La,Mg）Ni3及LaNi5和一个残余相LaNi2。快淬处理可以显著改善合金的电化学循环稳定性。导致合金失效的主要原因是电极表面被电解液剧烈腐蚀以及合金电极在电化学循环过程中的粉化。

Effects of Melt Spinning on Cycle Stability of La-Mg-Ni System A2B7-type Electrode Alloys

The La-Mg-Ni system A2B7-type La0.75-xZrxMg0.25Ni3.2Co0.2Al0.1（x = 0,0.05,0.1,0.15,0.2） electrode alloy are prepared by melt spinning technology.The structures of the as-cast and spun alloys were analyzed by XRD,SEM and TEM.The electrochemical cycle stabilities of all the experimental alloys are measured by an automatic galvanostatic system.The effects of the melt spinning on the structure and cycle stability of the alloys were investigated in detail.The failure mechanism of the alloy electrodes was investigated.The obtained results indicated that the as-cast and spun alloys have multiphase structure,including two major phases（La,Mg）Ni3 and LaNi5 as well as a residual phase LaNi2.The melt spinning significantly improves the electrochemical cycle stability.The radical reasons causing lose efficacy of the alloy electrodes are that the surface of the alloy electrodes is severely corroded by electrolyte and that the alloy electrodes are pulverized in process of the electrochemical charge-discharge cycle.