La-Mg-Ni系贮氢合金相结构及电化学性能  

Structure and Electrochemical Properties of La–Mg–Ni System Hydrogen Storage Alloy

作　　者：许剑轶[1,2] 胡峰[1,2] 王青春[1,2] 李霞[1,2] 王瑞芬[1,2] 张胤[1,2] 

机构地区：[1]内蒙古科技大学稀土学院,内蒙古包头014010 [2]内蒙古自治区白云鄂博矿多金属资源综合利用省部共建重点实验室,内蒙古包头014010

出　　处：《过程工程学报》2014年第2期335-339,共5页The Chinese Journal of Process Engineering

基　　金：内蒙古自然科学基金资助项目(编号:2011MS0803;2013MS0722);内蒙古科技大学创新基金资助项目(编号:2011NCL027)

摘　　要：采用感应熔炼法制备La0.75Mg0.25Ni3.4-xAl0.1Cox(x=0.0,0.5,1.0)贮氢合金,研究了合金元素Co对Ni部分替代对合金相结构及电化学性能的影响.结果表明,合金由La2Ni7相、LaNi5相及LaMg2Ni9相组成.随Co含量的增加,合金电极活化次数变化不大,最大放电容量、循环稳定性呈现先增后减的趋势.合金的最大放电容量和循环保持率分别由x=0时的316.92 mA.h/g和61.83%增加到x=0.5时的340.31 mA.h/g和75.21%,而后减少到x=1.0时的333.22mA.h/g和66.70%.而合金的高倍率放电性能降低,当放电电流密度为900 mA/g时,其倍率放电性能由62.49%(x=0)减小到53.68%(x=1.0).合金电极的极限电流、贮氢合金电化学反应电阻逐渐增大,其高倍率放电性能的降低源于电极表面的电子迁移速率和氢在合金体相中扩散速率的共同作用.The hydrogen storage alloy Lao.75Mg0.25Ni3.4.xA10.1Cox （x=0.0, 0.5, 1.0） was prepared by induction smelting. The effect of partial replacement of Ni by Co in the alloy on its structure and electrochemical properties was studied. The results show that the alloy consists of LaENi7 and LaMgENi9 phases and LaNi5 phase of CaCus type. The replacement of Ni by Co had a little effect on the activation property of alloy electrodes. The discharge capacity and cyclic stability of alloy electrodes increase first from 316.92 mA.h/g and 61.83% （x-=0） to 340.31 mA.h/g and 75.21% （x=0.5）, and then decreases to 333.22 mA.h/g and 66.70% （x=1.0） with increasing of Co content. The high rate discharge ability decreases with the addition of Co content. At the discharge current density of 900 mA/g, the high rate discharge ability of alloy electrodes decreases from 62.49% （x=0） to 53.68% （x=1.0）. The substitution leads to some increase in the limiting current density and electrochemical impedance spectroscopy. The deterioration of its high rate discharge ability can be ascribed to the synergic effect of electron transfer on the alloy surface and hydrogen diffusion in the bulk of alloy.

关 键 词：贮氢 La-Mg-Ni合金 晶体结构 电化学性能 电极 

分 类 号：TG139.7[一般工业技术—材料科学与工程]