快淬La—Mg—Ni系贮氢合金的电化学性能及微观结构

Electrochemical Performances and Microstructure of the Melt-Spun La-Mg-Ni System Hydrogen Storage Alloys

摘要:

采用铸造及快淬工艺制备了La—Mg-Ni系（PuNi3型）贮氢合金La0.7Mg0.3Ni2.55-Co0.45Cux（x=0～0．4），分析测试了铸态及快淬态合金的电化学性能与微观结构，研究了Cu替代Ni及快淬工艺对合金微观结构及电化学性能的影响。结果表明：铸态及快淬态合金具有多相结构，包括（La，Mg）Ni3相和LaNi5相和一定量的LaNi2相。快淬处理对合金的相组成没有影响，但使合会的衍射峰趋于均匀一致。Cu替代Ni使合金的电化学容量下降，但使合金的循环稳定性及放电电压特性得到改善。快淬可提高合金的循环稳定性，但使合金的容量下降。

Abstract:

La-Mg-Ni system (PuNi3-type) La0.7Mg0.3Ni2.55-xCo0.45Cux (x=0, 0.2, 0.4) hydrogen storage electrode alloys were prepared by casting and melt spinning process. The microstructure and electrochemical performances of the as-cast and melten spun alloys were analyzed and measured. The effects of substituting Ni with Cu and melt spinning on microstructures and electrochemical performances of the as-cast and melten spun alloys were investigated in detail. The obtained results show that the as-cast and melten spun alloys are composed of the (La, Mg)Ni3 phase and the LaNi5 phase as well as the LaNi2 phase. The melt spinning have an inappreciable influence on the phase compositions of the alloys, but leads to the homogeneity of the diffraction peaks of the alloys. The results obtained by the electrochemical measurement indicate that the substitution decreased the discharge capacities of the as-cast and melt spun alloys, whereas improved the cycle stability and discharge voltage characteristic of the as-cast and melten spun alloys. The melt spinning significantly improved the cycle stability of the alloys, but it notably decreased the discharge capacity of the alloys.