快凝储氢合金La_(0.8)Ce_(0.2)Ni_(4.65-x)Mn_(0.9)Ti_(0.05)(V_(0.3)Fe_(0.4)Al_(0.3))_x微观结构和电化学性能研究  

Microstructure and Electrochemical Properties of Melt-Spun La_(0.8)Ce_(0.2)Ni_(4.65-x)Mn_(0.9)Ti_(0.05)(V_(0.3)Fe_(0.4)Al_(0.3))_x Hydrogen Storage Alloys

作　　者：李新宇[1] 罗永春[1,2] 王浩[1] 康龙[1] 

机构地区：[1]兰州理工大学材料科学与工程学院,甘肃兰州730050 [2]兰州理工大学有色金属先进加工与再利用省部共建国家重点实验室,甘肃兰州730050

出　　处：《中国稀土学报》2015年第5期556-566,共11页Journal of the Chinese Society of Rare Earths

基　　金：国家高技术863计划研究项目(2011AA03A408)资助

摘　　要：采用熔铸和快凝技术制备过计量比AB5.6型储氢合金La0.8Ce0.2Ni4.65-xMn0.9Ti0.05（V0.3Fe0.4Al0.3）x（x=0~1.0）,研究了（V0.3Fe0.4Al0.3）对铸态和快凝合金相结构和电化学性能的影响。XRD和SEM结果表明：铸态合金组织由基体Ca Cu5型相和少量第二相组成;当x〈0.7时,快凝合金组织为计量比是AB5.5的Ca Cu5型单相组织,当x≥0.7后,合金中形成少量富La的La-Ni相;铸态与快凝合金的晶胞参数a,c及晶胞体积V均随x的增加而增加,快凝合金晶胞参数和晶胞体积明显大于铸态组织。室温（298 K）下铸态和快凝合金的放氢平台压随x的增加均依次降低,其中快凝合金放氢平台压降低幅度大。电化学测试结果表明：随x的增加,铸态和快凝合金电极的活化性能和最大放电容量均呈下降趋势,但电极循环稳定性逐渐提高;x=0.3~0.5时,快凝合金电极的最大放电容量为306~316 m Ah·g-1,经100次循环后的容量保持率S100达90%左右,快凝合金电极的循环寿命明显优于铸态合金。The over-stoichiometric AB5. 6-type La0.8Ce0.2Ni4.65-xMn0.9Ti0.05（V0.3Fe0.4Al0.3）x （ x = 0 - 1.0 ） hydro- gen storage alloy were prepared by as-cast and melt-spinning technique, the effect of （V0.3 Fe0.4Al0.3 ） additive on the phase structure and electrochemical properties of the as-cast and melt spun alloys were systematically investigated. The XRD and SEM results indicated that the as-cast alloys consisted of multi-phase compositions with main phase of CaCu5-type phase; and the melt-spun alloys consisted of single CaCu5-phase with stoichiometric ratio of AB5.5when x 〈0.7, then the melt-spun alloys consisted multi-phase with second phase LaNi when x ≥0.7. The lattice parameters （a, c） and volume （V） of as-cast and melt-spun alloys increased with increasing x, and further decreased after melt-spun process. The equilibrium hydrogen pressure （Peq） of as-cast and meh-spun alloys decreased with increasing x, and further decreased after melt-spun process. The electrochemical properties of alloy electrodes showed that the activation property and discharge capacity of alloy electrodes decreased with the increasing x, while the S100 （discharge capacity retention at 100th） of alloy electrodes were significantly improved with increasing x. The discharge capacity and S100 of melt-spun alloys （x = 0.3 -0.5 ） was about 306 -316 mAh .g-1 and 90%, respectively.

关 键 词：稀土系AB5.6型过计量比储氢合金 快凝处理 相组成与结构 电化学性能 

分 类 号：TG139[一般工业技术—材料科学与工程]