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为了改善La-Mg-Ni系A2B7型电极合金的动力学性能,用M(M=Zr,Pr)部分替代合金中的A侧元素La。用真空快淬技术制备了La0.5 5M0.2Mg0.25Ni3.2Co0.2Al0.1(M=Zr,Pr)电极合金,探索了快淬工艺参数对合金电化学贮氢动力学性能的影响。用XRD、SEM及TEM表征了铸态及快淬态合金的结构,结果发现,铸态及快淬态合金均由多相组成,包括两个主相(La,Mg)2Ni7和LaNi5以及残余相LaNi2。快淬Pr替代合金具有微晶、纳米晶结构,而在快淬Zr替代合金中发现明显的非晶相。电化学测试结果表明,合金的高倍率放电能力随淬速的增加先增加后减小。电化学交流阻抗(EIS)、Tafel极化曲线及电位阶跃测试的结果都表明,合金的电化学贮氢动力学性能随淬速的增加先上升后下降。
In order to improve the dynamic properties of La-Mg-Ni based A2B7 electrode alloy, M (M = Zr, Pr) was used to partially replace the A-side element La in the alloy. The La0.5 5M0.2Mg0.25Ni3.2Co0.2Al0.1 (M = Zr, Pr) electrode alloy was prepared by vacuum quenching technology, and the effect of technological parameters on the kinetic properties of the electrochemical hydrogen storage was investigated. The structures of the as-cast and quenched alloys were characterized by XRD, SEM and TEM. The results show that the as-cast and quenched alloys are composed of multiphase, including two main phases (La, Mg) 2Ni7 and LaNi5 and the residual phase LaNi2. Rapid quenching Pr substitution alloy with a microcrystalline, nanocrystalline structure, and in the rapidly quenched Zr substitutional alloy found significant amorphous phase. The electrochemical test results show that the high rate discharge capacity of the alloy first increases and then decreases with the increase of quenching rate. Electrochemical AC impedance (EIS), Tafel polarization curve and potentiometric test results show that the electrochemical hydrogen storage kinetics of the alloy first increases and then decreases with the increase of quenching rate.