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以钒基合金(TiCr)0.497V0.42Fe0.083为基体,通过掺入稀土-镁-镍系A2B7型合金(MlMg)2(NiCoAl)7作为电催化活性物,采用机械球磨改性方法制备了储氢合金复合电极材料(TiCr)0.497V0.42Fe0.083+x(%,质量分数)(MlMg)2(NiCoAl)7(x=5～50),系统研究了电催化活性物含量对球磨复合材料微观组织和电化学性能的影响规律。XRD和SEM分析结果表明,随x值的增加,球磨后A2B7型合金颗粒细化后分散并包覆在钒基合金表面上;与铸态钒基合金相比,复合材料中BCC固溶体相结构的晶胞参数a和晶胞体积V均明显减小。电化学性能测试结果表明,球磨复合材料电极的最大放电容量随着x值的增加呈先增加后减小的变化规律,当x?5时,复合材料电极的放电容量为280～433.2mAh.g-1,其100次充放电循环后的电极容量保持率S100为92%～98.9%,表现出良好的电极循环稳定性,其中x=30时的复合材料的综合电化学性能较佳,A2B7型合金的抗腐蚀性能及其包覆效果以及V元素的溶出行为对球磨复合储氢合金电极的电化学循环稳定性具有重要的影响。随A2B7型合金含量x的增加,球磨复合材料电极反应动力学得到显著提高,电极的高倍率放电性能(HRD)和交换电流密度I0值逐渐增加,但氢原子扩散系数有所减小,其中表面电催化活性是影响球磨复合材料(TiCr)0.497V0.42Fe0.083+x(%)(MlMg)2(NiCoAl)7电极反应动力学过程的主要控制步骤。
A rare-earth-magnesium-nickel type A2B7 alloy (MlMg) 2 (NiCoAl) 7 was electrocatalyzed with a vanadium-based alloy (TiCr) 0.497V0.42Fe0.083 as a matrix. (TiCr) 0.497V0.42Fe0.083 + x (%, mass fraction) (MlMg) 2 (NiCoAl) 7 (x = 5 ~ 50). The effects of the content of electrocatalytic active material Material microstructure and electrochemical properties of the law. The results of XRD and SEM showed that the A2B7 alloy particles were finely dispersed and coated on the surface of vanadium-based alloy with the increase of x value. Compared with as-cast vanadium-based alloy, the phase structure of BCC solid solution in the composite Cell parameters a and cell volume V were significantly reduced. The results of electrochemical tests show that the maximum discharge capacity of the composite electrode increases firstly and then decreases with the increase of x value. When x? 5, the discharge capacity of the composite electrode is 280 ~ 433.2mAh.g. -1, the electrode capacity retention rate after 100 cycles of charging and discharging S100 is 92% -98.9%, showing good cyclic stability of the electrode, wherein the composite electrochemical properties of the composite material at x = 30 are better, the A2B7 type The corrosion resistance of the alloy and its coating effect as well as the dissolution behavior of the V element have an important influence on the electrochemical cycling stability of the ball mill composite hydrogen storage alloy electrode. With the increase of the content of A2B7 alloy, the reaction kinetics of the ball-milled composite electrode was significantly improved, the HRD and exchange current density I0 gradually increased, but the hydrogen diffusion coefficient decreased, the surface The electrocatalytic activity is the main control step that influences the kinetics of the electrode reaction of 0.497V0.42Fe0.083 + x (%) (MlMg) 2 (NiCoAl) 7 in the ball mill composite (TiCr).