La-Mg-Ni系A2B7型贮氢合金表面包覆铜及其电化学性能

以A2B7型贮氢合金La1.5Mg0.5Ni7为研究对象,研究未包覆和表面包覆Cu以及对包覆铜的贮氢合金进行再包覆Ni、Co处理的合金电极电化学性能.实验结果表明,表面包覆Cu和Cu-Ni后的贮氢合金电极循环稳定性有所提高,而包覆Cu-Co的合金电极稳定性较差,但电极容量有所提高.线性极化扫描和电化学阻抗图谱分析结果表明,包覆Cu、Cu-Co及Cu-Ni处理改善合金电极的交换电流密度I0,降低电化学阻抗,说明包覆处理改善合金表面的电催化活性,加快合金表面电荷的迁移速率,从而提高高倍率放电能力.

Copper coating of La-Mg-Ni-serial A2B7-type hydrogen storage alloy and its electrochemical properties

Taking A2B7-type hydrogen storage alloy La15Mg0.5Ni7 as an investigation object,the electrochemical properties of the alloy electrode with copper coating,without it,and with additional coating with Ni and Co were investigated.It was indicated by the experimental result that surface coating with copper and copper-nickel resulted in increasing the cycling stability of hydrogen storage alloy electrode;surface coating with copper-cobalt improved electrode capacity,but the cycling stability was not increased.It was also showed by the results of linear polarization and impedance spectroscopy that hydrogen storage alloys coated could increase the exchange current density I0 and reduce the electrochemical reaction resistance,illustrating that the surface coating could increase electrocatalytic activity and enhance the diffusivity of electric charge in alloy surface,so that the high-rate discharge performance of the coated electrode was improved.