Abstract: Taking A2B7-type hydrogen storage alloy La1.5Mg0.5Ni6.5Co0.5 as an investigation object, the kinetic properties of the alloy electrode with copper coating by the different chroma of vitriol and without it were studied. The high rate discharge performance of hydride electrode was analyzed from the point of kinetic view. The results showed that the exchange current density I0 of hydride electrode coated by Cu increased obviously with increasing chroma of vitriol. The limiting current density IL of the alloy electrodes increased from 2166.01 mA/g [C(H2SO4)=0.025 mol/L] to 2681.93 mA/g [C(H2SO4)＝0.1 mol/L]. The diffusion coefficient, Dα, of hydrogen in α-phase of hydride electrode was improved with increasing chroma of vitriol. All of the above indicate that the Cu surface microencapsulation can effectively improve the kinetic performance of hydrogen absorption and releasing process of hydride electrode1. The improvement of high-rate discharge ability can be ascribed to the effects of the charge-transfer on the alloy surface and hydrogen diffusion rate in the bulk of alloy.

Key words: A2B7-type hydrogen storage alloy, chemical copper microencapsulation, high rate discharge performance, kinetic analysis

摘要： 以A2B7型贮氢合金La1.5Mg0.5Ni6.5Co0.5为对象，用不同浓度硫酸溶液浸蚀合金粉末进行化学镀铜，系统研究了未包覆以及表面包覆Cu后对La1.5Mg0.5Ni6.5Co0.5合金电极动力学性能的影响，从动力学的角度对贮氢电极高倍率放电性能进行了分析. 结果表明，与未包覆Cu相比，包覆后合金电极的交换电流密度增大且随着H2SO4浓度的增加而增大. 其极限电流也逐渐增大，从H2SO4浓度为0.025 mol/L时的2166.01 mA/g增加到0.1 mol/L时的2681.93 mA/g. 合金电极中氢的扩散速率得到不同程度的提高. 表明化学镀铜能有效地提高贮氢合金电极吸、放氢过程的动力学性能. 其高倍率放电性能的改善是源于电极表面的电子迁移速率和氢在合金体相中扩散速率共同作用所引起的.

关键词: A2B7型贮氢合金, 化学镀铜, 高倍率性能, 动力学分析