Effect of Al and W substitution for Ni on the microstructure and electrochemical properties of La_1.3CaMg_0.7Ni_9-x(Al_0.5W_0.5)_x hydrogen storage alloys

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• 作者：Peng Zhang ; Yongning Liu ; Jiewu Zhu ; Xuedong Wei ; Guang Yu
• 关键词：Hydrogen storage alloys ; Microstructure ; Ni-MH battery ; Electrochemical properties
• 刊名：International Journal of Hydrogen Energy
• 出版年：2007
• 出版时间：September 2007
• 年：2007
• 卷：32
• 期：13
• 页码：2488-2493
• 全文大小：608 K

文摘

The microstructure and electrochemical properties of La_1.3CaMg_0.7Ni_9-x(Al_0.5W_0.5)_x (x=0,0.3,0.6,0.9) hydrogen storage alloys have been studied systematically. XRD and SEM analyses show that the alloys are mainly composed of the(La,Mg)Ni₃ phase and the LaNi₅ phase, but the Al and W substitution for Ni results the disappearance of the (La,Mg)₂Ni₇ phase and the segregation of W pure metal phase. The cell volumes of the (La,Mg)Ni₃ phase and the 38697df08835aa4b83a"" title=""Click to view the MathML source"">LaNi₅ phase increase by adding the content of Al. With increasing x, the maximum discharge capacity of the alloy electrodes decreases from 380 (x=0.0) to 317.6 mA h/g (x=0.9). However, cyclic stability is noticeable improved from 72.2 % (x=0.0) to 85.2 % (x=0.9) up to 100 cycles. The HRD and exchange current density I₀ of the alloy electrodes decrease first and then increase.