LaNi_(3.8-x)Al_x(0≤x≤0.5)多相储氢合金的结构及电化学性能  

Structure and Electrochemical Properties of LaNi_(3.8-x)Al_x(0≤x≤0.5) Multiphase Hydrogen Storage Alloys

作　　者：闫小龙[1] 刘增彦[1] 宋秀芹[1] 柴玉俊[1] 侯登录[2] 

机构地区：[1]河北师范大学化学与材料科学学院,河北石家庄050016 [2]河北师范大学物理与信息工程学院,河北石家庄050016

出　　处：《中国稀土学报》2011年第3期360-364,共5页Journal of the Chinese Society of Rare Earths

基　　金：国家自然科学基金(50901030)资助

摘　　要：采用真空电弧熔炼法制备了LaN i3.8-xA lx(0≤x≤0.5)储氢合金,并在氩气气氛中进行退火处理。通过X射线衍射(XRD),S ievert′s方法和电化学测试分别分析了合金的物相结构、储氢和电化学性能。研究结果表明:LaN i3.8-xA lx(0≤x≤0.5)合金主要由LaN i5,Ce2N i7,Pr5Co19和Ce5Co19型相组成。随着A l的变化,各相相丰度发生变化,而相丰度的变化影响了合金的滞后和吸/放氢平台压力。随着x的增加,LaN i3.8-xA lx(0≤x≤0.5)合金的放电容量先增大至270 mAh.g-1(x=0.3),然后缓慢降低;在x=0.3时合金显示出较好的充/放电循环稳定性。极化电阻和电化学交流阻抗则随着x的增加缓慢降低,交换电流密度增大,导致高倍率放电有所增大。The LaNi3.8-xAlx（0≤x≤0.5） hydrogen storage alloys were prepared by arc melting followed by an annealing treatment in argon.The structure,hydrogen storage and electrochemical properties were investigated by means of X-ray diffraction（XRD）,Sievert′s method and electrochemical measurements.The results showed that these alloys were composed of CaCu5,Ce2Ni7,Pr5Co19 and Ce5Co19 type phase.With increasing Al content,the phase abundance of each phase varied,which affected the hysteresis and the hydriding/dehydridng plateau pressure of LaNi3.8-xAlx（0≤x≤0.5） alloys.With increasing Al content,the discharge capacity of LaNi3.8-xAlx（0≤x≤0.5） alloys firstly increased to 270 mAh · g-1（x=0.3）,and then slightly decreased.The good cyclic stability was obtained at x=0.3.The polarization resistance and the electrochemical impedance slightly decreased with increasing x,whereas the exchange current density slowly increased.Correspondingly,the HRD increased.

关 键 词：多相合金 储氢合金 电化学性能 稀土 

分 类 号：O643[理学—物理化学] TG139[理学—化学]