铁对快凝稀土系贮氢合金AB_(5.6)微观结构和电化学性能的影响  

Influence of Addition of Iron on Microstructure and Electrochemical Properties of As-Spun AB_5-Type Hydrogen Storage Alloys

作　　者：罗永春[1] 阎汝煦[1] 康龙[1] 

机构地区：[1]兰州理工大学甘肃省有色金属新材料省部共建国家重点实验室,甘肃兰州730050

出　　处：《中国稀土学报》2008年第4期461-468,共8页Journal of the Chinese Society of Rare Earths

基　　金：甘肃省"十五"科技攻关项目(Sz001-A52-05)资助

摘　　要：采用单辊快甩凝固技术制备了过化学计量比稀土系贮氢合金La（NiMn）5.6-xFex（x=0-0.5）,研究了Fe及快淬速度对合金电极性能及微观结构的影响。结果表明,过化学计量比快淬合金的相结构均为过饱和CaCu5单相,且随Fe的增多,合金晶胞体积基本呈线性增加,放电平台压力值递减,合金电极的放电容量增大且电极循环稳定性得到有效提高;当x≥0.4时,合金最大放电容量为341 mAh·g^-1,经200次循环后电极容量保持率大于96.2%,1C和2C放电时的HRD分别为88%-89.8%和62%-70%。不同淬速条件下合金凝固组织形貌和晶态存在明显差别,淬速对合金的电极性能有明显影响;当x=0.3,淬速为10 m·s^-1时,合金电极有良好的综合电化学性能。The rare earth based over-stoichiometric AB5 type LaNi4.68- xFexMn0.93 （ x = 0 - 0.5） hydrogen storage alloys were prepared by rapidly quenching. The effects of Fe addition on the microstructures and electrochemical properties of the quenched alloys were investigated comprehensively. The experimental results showed that the phase structures of the quenched alloys LaNi4.68-x FexMn0.93（x = 0 - 0. 5） were only composed of CaCu5 type phase. Both the lattice parameters and the unit cell volume increased, and equilibrium hydrogen pressure decreased with the increase of Fe content x. The electrochemical measurement indicated that the addition of Fe enhanced discharge capacities and dramatically modified the cycle life of the quenched alloys. For alloys with x ≥ 0.4 and quenching rate of 35 m· s^- 1, the maximum discharge capacities of the quenched alloys reached 341 mAh·g^-1 and the rate of capacity retention （S200） after 200 charge/discharge cycles was about 96.2%, the high rate discharge ability （HRD） of the electrodes at IC and 2C reached 88% - 89.8% and 62% - 70%, respectively. Effects of the quenching rate on the microstructural morphologies and electrochemical properties were substantial, and the alloys with x = 0.3 and quenching rate of 10 m·s^-1 had best overall electrochemical properties.

关 键 词：无钴AB5型合金 快速凝固 铁 微观结构 电化学性能 稀土 

分 类 号：TG139[一般工业技术—材料科学与工程]