摘要
研究Si和Zn元素分别部分替代Ni后合金La0375Mg0.25Ni3.5-xMx（M=Si9Zn；x=0-0.5）的微观组织及电化学性能．X射线衍射（XRD）结果表明，La0.75Mg0.25Ni3．5-xSix合金由CaCus型相、Ce2Nb型相和LaMgNi4型相组成，随着Si含量增加，CaCu5型相明显增加．La0．75Mg0．25Ni3.5-xZnx合金由CaCu5型相、CezNi，型相和LaNi3型相组成．随着Zn的增加，合金中CezNi7型相逐渐减少，CaCu5型相和LaNi3型相则相应增加．电化学实验表明，2种元素的加入均使得合金的高倍率放电性能下降；Si的加入降低了合金最大放电容量和交换电流密度，但活化次数也随之减少，电化学循环稳定性提高．Zn元素的加入，对合金最大放电容量影响较小．
The micro-structure and electrochemical properties of thus formed quaternary alloys Lao.TsMg0.25Ni3.5-xM,（M=Si,Zn;x=0-0. 5）was investigated after replacing the portion of Ni by Si or Zn in Lao. 75 Mg0. 2s Ni3. 5. The analysis of X-ray diffraction （XRD） showed that La0. 75 Mg0. 25 Ni3.5-x Six consisted of CaCus-type phase, Ce2 NiT-type phase, and LaMgNi4-type phase, and the La0. 75 Mg0. 25Ni3. 5-xZnx consis- ted of CaCus-type phase, Ce2Ni7-type phase, and LaNi3-type phase. The increase of Si content led to an increase of the content of LaNi5-type phase. The increase of Zn content led to an decrease of content of Ce2NiT-type phase, but the LaNi3-type phase and CaCu5-type phase would increase at the same time. The electrochemical test indicated that the high rate dischargeability of alloy electrodes would decreases when either of the two elements was added. The maximum discharge capacity and the exchange current density （Io） of the alloy electrodes would decrease, but the activation properties would increas and the cyclic stability of the alloys improve with the Si content. The maximum discharge capacity of the alloy electrodes would be decreased a little when the Zn was added.
出处
《兰州理工大学学报》
CAS
北大核心
2008年第6期9-14,共6页
Journal of Lanzhou University of Technology
基金
国家自然科学基金(50171021)
关键词
储氢合金
相结构
电化学性能
hydrogen storage alloys
phase structure
electrochemical properties
