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采用感应熔炼方法制备了La0.75Mg0.25Ni3.5-xCox(x=00,.250,.751,)四元贮氢合金,系统地研究了合金B侧Co对Ni部分替代对合金相结构及电化学性能的影响。X衍射(XRD)分析表明,La0.75Mg0.25Ni3.5-xCox由(La,Mg)2Ni7相(包括Gd2Co7型高温相和Ce2Ni7型低温相)组成。此外,随着Co元素的加入,该类合金中出现CaCu5型LaNi5相。电化学测试表明,随Co含量的增加,合金电极活化次数增大,合金电极的最大放电容量增大,合金的最大放电容量由x=0.25时的376.53 mAh/g增加到x=1时的401.62mAh/g,氢扩散系数增大,循环稳定性变差,合金的高倍率放电性能降低,Co含量对合金电极高倍率放电性能HRD值的影响与对合金电极交换电流密度的影响趋势一致,这表明电极合金表面的电化学反应对合金的动力学性能影响更大。
The La0.75Mg0.25Ni3.5-xCox (x = 00, .250, .751,) four-element hydrogen storage alloy was prepared by induction melting method. The phase structure of La0.75Mg0.25Ni3.5- Electrochemical properties of the impact. X-ray diffraction (XRD) analysis shows that La0.75Mg0.25Ni3.5-xCox is composed of (La, Mg) 2Ni7 phase (including the high temperature phase of Gd2Co7 and the low temperature phase of Ce2Ni7 type). In addition, with the addition of Co element, CaCu5-type LaNi5 phase appears in this kind of alloy. The electrochemical tests showed that with the increase of Co content, the activation times of the alloy electrodes increased and the maximum discharge capacity of the alloy electrodes increased. The maximum discharge capacity of the alloy increased from 376.53 mAh / g at x = 0.25 to 401.62 at x = 1 mAh / g, the hydrogen diffusion coefficient increases, the cycle stability deteriorates and the high rate discharge performance of the alloy decreases. The effect of Co content on the high rate discharge HRD of the alloy electrode has the same trend with the exchange current density. It shows that the electrochemical reaction on the surface of the electrode alloy has a greater influence on the kinetic performance of the alloy.