PuNi_3和Ce_2Ni_7型贮氢合金电极容量衰减的交流阻抗谱分析

Analysis of alternating current impedance spectrum of capacity of PuNi_3 and Ce_2Ni_7-type hydrogen storage alloyed electrodes

测试不同循环状态下PuNi3和Ce2Ni7型贮氢合金电极在放电深度为50%条件下的电化学交流阻抗谱,分析电极反应的等效电路图.结果表明,随循环次数的增加,PuNi3型合金和Ce2Ni7型合金电极的表面电荷反应阻抗(R4)和接触阻抗(R2,R3)均随循环次数的增加呈先减小后增大的趋势,且PuNi3型合金电极表面电荷反应阻抗(R4)较Ce2Ni7型合金电极先达到最小值.在后期循环过程中,PuNi3型合金电极的表面电荷反应阻抗(R4)及颗粒之间的接触阻抗(R2,R3)均明显大于Ce2Ni7型合金电极,这说明PuNi3型合金电极在循环过程中的腐蚀与粉化均比Ce2Ni7型合金电极严重.

Electrochemical alternate impedance spectroscopy （EIS） of PuNi3 and Ce2Ni7-type hydrogen storage alloyed electrodes was measured at different cyclic conditions under the same depth of discharge （50%DOD）. Equivalent circuit of, the electrode was analysed. The results showed that the both of surface reaction resistance（R4） and contact resistance（R2 ,R3） decreased at first and then increased with the cycle numbers; the least magnitude of surface reaction resistance of PuNi3-type metal hydride electrode was reached earlier than Ce2Ni7-type metal hydride; The both of surface reaction resistance and contact resistance of PuNi3-type metal hydride electrode were remarkably larger than those of Ce2Ni7-type metal hydride during further cycling process, so that which indicated that the cauterization and pulverization of PuNi3- type metal hydride electrode were worse than those of Ce2 Ni7-type metal hydride electrode.