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采用筛分法测试了La0.75Mg0.25Ni3.3Co0.5储氢合金粉的粒度分布。结果表明,随着合金颗粒度减小,相应颗粒度的合金含量(质量分数)几乎呈线性增加,从合金颗粒度为58μm时的21%增加到38μm时的29%。同时,选用不同颗粒度的La0.75Mg0.25Ni3.3Co0.5合金粉制备了储氢合金电极,研究了合金颗粒度对储氢合金电极的活化性能、最大放电容量、放电特性以及循环稳定性的影响规律与机制。研究表明,合金颗粒度的大小对合金电极的活化性能基本无影响,合金电极均具有好的活化性能,经1至2个循环后达到最大放电容量。随着合金颗粒度的减小,合金电极的最大放电容量持续增加,从合金颗粒度为58μm时的332.5 m Ah·g-1增加到38μm时的最大值342.9 m Ah·g-1;放电中值电位先降低后升高,由合金颗粒度为58μm时的1.0302 V减小到45μm时的0.9825 V,然后增加到38μm时的1.0141 V;容量衰减速度呈现出先变慢后加快的变化规律。综合比较,在合金颗粒度为48μm时,La0.75Mg0.25Ni3.3Co0.5储氢合金电极展示了最佳的综合电化学性能,电化学性能的改善主要归因于合金电极电荷转移速度的加速和内阻的减小。
The particle size distribution of La0.75Mg0.25Ni3.3Co0.5 hydrogen storage alloy powder was tested by sieving method. The results show that with the decrease of alloy particle size, the alloy content (mass fraction) of the corresponding particle size almost linearly increases from 21% at the alloy particle size of 58μm to 29% at 38μm. At the same time, hydrogen storage alloy electrodes were prepared by using La0.75Mg0.25Ni3.3Co0.5 alloy powders with different particle sizes. The effects of alloy particle size on activation properties, maximum discharge capacity, discharge characteristics and cycle stability of hydrogen storage alloy electrodes Affect the law and mechanism. The results show that the size of the alloy particle has little effect on the activation performance of the alloy electrode, and the alloy electrode has good activation performance and reaches the maximum discharge capacity after 1 to 2 cycles. With the decrease of alloy particle size, the maximum discharge capacity of the alloy electrode increased continuously from 332.5 m Ah · g-1 at the particle size of 58 μm to 342.9 m Ah · g-1 at 38 μm. The value of potential decreases first and then increases from 1.0302 V at 58 μm to 0.9825 V at 45 μm and then increases to 1.0141 V at 38 μm. The rate of capacity decay increases first and then accelerates. In a comprehensive comparison, the best electrochemical performance of La0.75Mg0.25Ni3.3Co0.5 hydrogen storage alloy electrode was obtained when the alloy particle size was 48μm. The improvement of electrochemical performance was mainly attributed to the acceleration of the charge transfer rate of the alloy electrode And reduce the internal resistance.