电化学性能的影响
(1. 青岛大学 化学化工与环境学院，青岛 266071；
2. 浙江大学 材料科学与工程学院，杭州 310027)
摘 要: 采用熔体快淬法制备(Mg70.6Ni29.4)92La8贮氢合金带，研究快淬速率对合金的微观组织结构及其电化学性能的影响。结果表明：随着快淬速率的加快，合金由纳米晶向非晶过渡，合金的非晶化程度增强，合金带的最大放电容量增加。冷却辊线速度为21.8 m/s制备的合金的循环最大放电容量可达568.5 mA∙h/g，经过20次循环后，其最高容量保持率达79.3%；合金样品充电完成后形成的氢化物主要是Mg2NiH4，同时还保留大量的非晶结构。循环伏安测试结果显示较明显的氧化峰和还原峰，且峰电位差较小，反映电极合金具有较好的吸放氢反应的可 逆性。
关键字: Mg-Ni-La系贮氢合金；微观结构；电化学性能；熔体快淬
（1. College of Chemistry, Chemical and Environmental Engineering, Qingdao University, Qingdao 266071, China;
2. College of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, China）
Abstract:Hydrogen-storage (Mg70.6Ni29.4)92La8 alloys were prepared by melt-spinning. The effects of velocities of cooling roll on the microstructures and electrochemical properties for the as-quenched ribbons were investigated. The results show that the microstructure is transformed from nanocrystallization to amorphous phase, the degree of short-range order and the discharge-capacity increases with increasing the velocity of cooling roll for (Mg70.6Ni29.4)92La8 alloys. The highest discharge capacity reaches 568.5 mA·h/g for (Mg70.6Ni29.4)92La8 sample at the velocity of 21.8 m/s. The capacity conservation rate of the alloy is 79.3% after 20 cycles. It is obvious that Mg2NiH4 phase is major product with many amorphous phases during the charging process. Cyclic voltammetry results indicate significant peaks responding to oxidation and reduction reactions, and the difference between peak potentials is small, which means good reversibility of the electrode during the charge/discharge reaction.
Key words: Mg-Ni-La hydrogen-storage alloy; microstructure; electrochemical property; melt-spinning
