Fe部分替代Cu对低钴AB_5型贮氢合金相结构和电化学性能的影响  

Effect of Partial Substitution of Cu by Fe on the Phase Structure and Electrochemical Property of Low-Co AB_5 Type Hydrogen Storage Alloys

作　　者：杨素霞[1] 李媛[1] 刘治平[2] 杨淑琴[1] 韩树民[1,2] 

机构地区：[1]燕山大学环境与化学工程学院,河北秦皇岛066004 [2]燕山大学亚稳材料制备技术与科学国家重点实验室,河北秦皇岛066004

出　　处：《物理化学学报》2010年第8期2144-2150,共7页Acta Physico-Chimica Sinica

基　　金：国家自然科学基金(20673093)资助项目~~

摘　　要：为了获得既具有较高电化学容量又具有良好循环稳定性的低钴AB5型贮氢合金,研究了Fe部分替代Cu对低钴AB5型贮氢合金相结构和电化学性能的影响.采用真空感应熔炼方法,制备了一系列含Cu和Fe的低钴AB5型贮氢合金LaNi3.55Mn0.35Co0.20Al0.20Cu0.85-xFex(x=0.10,0.20,0.25,0.40,0.60).粉末X射线衍射(XRD)分析表明,合金含有单一CaCu5型六方结构的LaNi5相,Fe部分替代Cu并没有改变合金的本体相结构,但随着Fe含量的增大,晶格参数a,c和晶胞体积V增大.电化学性能测试表明,随着x增加,合金的放电容量和高倍率放电能力降低,但是循环稳定性得到了显著提高.当x从0.10增加到0.60时,合金的200周循环稳定性(S200)从77.6%提高到89.9%.Fe替代Cu有利于提高合金的循环稳定性,这主要是随着Fe替代量增大,晶胞体积增大,晶格体积膨胀率明显减小,合金的抗粉化能力增强.To obtain low-Co AB5 type hydrogen storage alloys with high discharge capacity and good cycling stability, the effects of substituting Cu with Fe on the phase structure and electrochemical performance of low-Co AB5 type hydrogen storage alloys were investigated in detail. A series of low-Co type LaNi3.55Mn0.35Co0.20Al0.20Cu0.85-xFex （x= 0.10, 0.20, 0.25, 0.40, 0.60） hydrogen storage alloys containin Cu and Fe were prepared by vacuum induction melting. X-ray diffraction （XRD） indicates that the alloys consist of a single LaNi5 phase with a hexagonal CaCu5 structure and the bulk phase structure of the alloy is not changed by the partial substitution of Fe for Cu. The parameters a, c, and the cell volume （V） increase with increasing Fe content. Electrochemical tests show that the maximum discharge capacity and the high rate dischargeability decrease but that the cycling stability of the alloy electrodes enhances significantly with increasing x. The capacity retention of the alloy electrodes at the 200th cycle （S200） increases from 77.6% （x=0.10） to 89.9% （x=0.60）. Substituting Cu with Fe enhances the cycle stability of the alloys because of an increase in cell volume which results in a lower expansion rate and a better anti-pulverization capability.

关 键 词：NI-MH电池 低钴型贮氢合金 元素替代 相结构 电化学性能 

分 类 号：TG139.7[一般工业技术—材料科学与工程]