Annealed alloys of AB5 type La0.7-xYxCe0.3Ni3.9Co0.45Mn0.35Al0.3 (x=0, 0.1, 0.2, 0.3, 0.4) were prepared by vacuum arc melting and heat treatment (1000 ℃×10 h). The effects of rare earth Y element on the microstructure, phase structure and electrochemical properties of the annealed alloy were investigated. The results of XRD and SEM electron microscopy showed that the microstructure of the annealed alloy has a matrix of CaCu5 phase and a small amount of second phase. With the increase of rare earth Y content x, the unit cell parameters a, c and unit cell volume V of the main phase decrease sequentially. Electrochemical test results show the capacity retention rate after 100 charge and discharge cycles is S100=77.6%~88.1%, and the high-rate discharge performance of the alloy electrode is HRD900=86.9%~92.7%. The addition of the Y has a significant effect on improving the cycle life of the alloy. The alloy with Y content x=0.2 has good comprehensive electrochemical performance. The cycle life after 100 charge and discharge is S100=88.1%, and the high rate discharge performance is HRD900=92.9%. The reaction kinetics of the alloy electrode is controlled by the surface charge transfer rate of the alloy and the diffusion of hydrogen in the bulk phase of the alloy. © 2020, Editorial Office of Journal of the Chinese Society of Rare Earths. All right reserved.
