Acta Phys. -Chim. Sin. ›› 2010, Vol. 26 ›› Issue (08): 2144-2150.doi: 10.3866/PKU.WHXB20100647

• ELECTROCHEMISTRY • Previous Articles     Next Articles

Effect of Partial Substitution of Cu by Fe on the Phase Structure and Electrochemical Property of Low-Co AB5 Type Hydrogen Storage Alloys

YANG Su-Xia1, LI Yuan1, LIU Zhi-Ping2, YANG Shu-Qin1, HAN Shu-Min1,2   

  1. 1. College of Environmental and Chemical Engineering, Yanshan University, Qinhuangdao 066004, Hebei Province, P. R. China;
    2. State Key Laboratory of Metastable Materials Science and Technology, Yanshan University, Qinhuangdao 066004, Hebei Province, P. R. China
  • Received:2010-01-16 Revised:2010-03-08 Published:2010-07-23
  • Contact: HAN Shu-Min E-mail:hanshm@ysu.edu.cn
  • Supported by:

    The project was supported by the National Natural Science Foundation of China (20673093).

Abstract:

To obtain low-Co AB5 type hydrogen storage alloys with high discharge capacity and good cycling stability, the effects of substituting Cu with Fe on the phase structure and electrochemical performance of low-Co AB5 type hydrogen storage alloys were investigated in detail. A series of low-Co type LaNi3.55Mn0.35Co0.20Al0.20Cu0.85-xFex (x= 0.10, 0.20, 0.25, 0.40, 0.60) hydrogen storage alloys containin Cu and Fe were prepared by vacuum induction melting. X-ray diffraction (XRD) indicates that the alloys consist of a single LaNi5 phase with a hexagonal CaCu5 structure and the bulk phase structure of the alloy is not changed by the partial substitution of Fe for Cu. The parameters a, c, and the cell volume (V) increase with increasing Fe content. Electrochemical tests show that the maximum discharge capacity and the high rate dischargeability decrease but that the cycling stability of the alloy electrodes enhances significantly with increasing x. The capacity retention of the alloy electrodes at the 200th cycle (S200) increases from 77.6% (x=0.10) to 89.9% (x=0.60). Substituting Cu with Fe enhances the cycle stability of the alloys because of an increase in cell volume which results in a lower expansion rate and a better anti-pulverization capability.

Key words: Ni-MH battery, Low-Co type hydrogen storage alloy, Element substitution, Phase structure, Electrochemical performance

MSC2000: 

  • O646