Mo对储氢合金RE_(0.78)Mg_(0.22)(Ni_(0.84-x)Co_(0.15)Al_(0.01)Mo_x)_(3.5)的结构及电化学性能的影响  

Effect of Mo content on structure and electrochemical characteristics of RE_(0.78)Mg_(0.22)(Ni_(0.84-x)Co_(0.15)Al_(0.01)Mo_x)_(3.5) hydrogen storage alloys

作　　者：汪保国[1] 杨传铮[2] 王丹[1] 张灏[1] 夏保佳[2] 何丹农[1] 

机构地区：[1]纳米技术及应用国家工程研究中心能源研究室,上海200241 [2]中国科学院上海微系统与信息技术研究所,上海200050

出　　处：《电源技术》2010年第8期822-825,共4页Chinese Journal of Power Sources

基　　金：上海市闵行区科委创新基金项目(2010MH031)

摘　　要：采用XRD分析了La0.50Pr0.22Nd0.06Mg0.22(Ni0.84-xCo0.15Al0.01Mox)3.5(x=0.00,0.01,0.02,0.03和0.04)合金的晶体结构,并且系统地研究了合金的气固相储氢特性和电化学性能。结果表明,合金由Ce2Ni7型结构的A2B7主相和少量的具有CaCu5结构的AB5相构成,晶轴比c/a随着Mo含量的增大而增大。合金在吸放氢过程中的熵变DS和焓变DH与AB5型合金的数值相当。合金的电化学容量随Mo含量的增加而减小,由x=0.00时的381.2 mAh/g下降到x=0.01时的379.5 mAh/g,再至x=0.04时合金的容量最大为362.0 mAh/g;合金容量的衰减速率因Mo的掺入而变大,由x=0.00时的-0.23 mAh/(g.次)降为x=0.04时的-0.97 mAh/(g.次);合金的倍率性能在x=0.01时得以改善,改善幅度为4%。研究表明当x≤0.01时不仅保持了合金的高容量,而且改善了合金的高倍率性能。The influence of Mo content on the crystal structure,thermodynamics and electrochemical properties of La0.50Pr0.22Nd0.06Mg0.22（Ni0.84-xCo0.15Al0.01Mox）3.5（x=0.00,0.01,0.02,0.03 and 0.04）alloys was studied systematically.The phase structures were identified by X-ray diffraction（XRD）.The results show that all these alloys consist of two phases： the main phase is La2Ni7 phase with the Ce2Ni7-type structure and a few phase is LaNi5 with CaCu5-type structure.The value of c /a increases with the increase of Mo content.The properties of hydrogen absorption and de-absorption were determined by pressure-composition-temperature（P-C-T）.The results reveal that the enthalpy（ΔH） and entropy（ΔS） of these alloys are similar to that of the AB5 systems.The electrochemical analysis shows that the increase of Mo leads to some decrease in both the discharge capacity and cycling stability,but leads to the improvement in the HRD（high-rate discharge property） of alloys.The discharge capacity decreases from 381.2 mAh/g（x=0.00） to 362.0 mAh/g（x=0.04） and the decrease rate of capacity,from-0.23 mAh/（g.time）（x=0.00） to-0.97 mAh/（g.time）（x=0.04）.However,the capability of HRD is best when x=0.01.This research reveals when x≤0.01,not only the higher discharge capacity is remained,but also HRD is improved.

关 键 词：储氢合金 La2Ni7相 LaNi5相 PCT性能 电化学性能 

分 类 号：TM910.4[电气工程—电力电子与电力传动]