还原剂处理对La-Mg-Ni系A_2B_7型贮氢合金性能的影响  

Effect of surface treatment on reducing agent of La-Mg-Ni based A_2B_7 type hydrogen storage alloys

作　　者：许剑轶[1] 张博[1] 李霞[1] 张国芳[1] 王瑞芬[1] XU Jian-yi;ZHANG Bo;LI Xia;ZHANG Guo-fang;WANG Rui-fen(School of Materials and Metallurgy, Inner Monglia University of Science and Technology, Baotou Inner Mongolia 014010, China)

机构地区：[1]内蒙古科技大学材料与冶金学院,内蒙古包头014010

出　　处：《电源技术》2017年第7期1004-1006,1070,共4页Chinese Journal of Power Sources

基　　金：国家自然科学基金(51501095)

摘　　要：以A_2B_7型贮氢合金La_(0.75)Mg_(0.25)Ni_(3.3)Co_(0.25)为对象,用不同还原剂对贮氢合金进行表面处理,系统研究了还原处理前后合金电极电化学性能的影响。结果表明:与未处理相比,还原剂处理后合金电极活化次数只需2次即可活化,明显改善电池的活化性能,合金电极的循环寿命比未处理合金显著提高,三种不同还原剂KBH_4、N_2H_4、NaH_2PO_2处理后的合金电极100次循环保持率分别为75.33%、78.70%、89.29%。合金电极的高倍率放电性能依次增加,但高于未处理合金,从动力学的角度对贮氢电极高倍率放电性能进行了分析。结果表明,与未处理相比,三种不同还原剂KBH_4、N2H_4、NaH_2PO_2处理后的合金电极的交换电流密度依次增大,其极限电流也逐渐增大,循环伏安氧化峰面积和峰电流也出现同样变化。表明表面还原处理能有效提高贮氢合金电极吸、放氢过程的动力学性能,其高倍率放电性能的改善是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这两方面共同作用所引起的。Taking A2B7-type hydrogen storage alloy La0.75Mg0.25Ni3.3Co0.25as an investigation object,the electrochemical properties of the alloy electrode treated by various reducers were studied.The results show that the treatment of reducing agent has an obvious effect on the activation property(the number of activation was only2time).Compared with untreated alloy,the surface treatment on reducing agent can greatly improve the mechanical properties of the alloys.100for treatment on KBH4,N2H4,NaH2PO2are75.33%,78.70%and89.29%,respectively.The high rate discharge performance of hydride electrode was analyzed from the point of kinetic view.The results show that the exchange current density0and limiting current density L of hydride electrode handling for KBH4,N2H4,NaH2PO2can be increased successively.The change in cyclic voltammograms oxidation peak area and electricity peaks of the alloy electrodes was similar for0and L.All of the above indicate that the reduction treatment on the surface can effectively improve the kinetics performance of hydrogen absorbing and releasing processes of hydride electrode.The improvement of the high-rate discharge ability can be ascribed to the effect of the charge-transfer on the alloy surface and hydrogen diffusion rates in bulk of alloy.

关 键 词：A2B7型贮氢合金 表面还原剂处理 电化学性能 

分 类 号：TM912[电气工程—电力电子与电力传动]