Electrochemical and Hydrogen Transport Kinetic Performance of MlNi3.75Co0.65Mn0.4Al0.2 Metal Hydride Electrodes at Various Temperatures
Electrochemical and Hydrogen Transport Kinetic Performance of MlNi3.75Co0.65Mn0.4Al0.2 Metal Hydride Electrodes at Various Temperatures
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DOI：
10.1149/1.1453408
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发表时间：
2002-04
影响因子：
3.9
通讯作者：
Xianxia Yuan;Naixin Xu
中科院分区：
文献类型：
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作者：
Xianxia Yuan;Naixin Xu
在-20至85°C的温度范围内系统地研究了MlNi 3.75 Co 0.65 Mn 0.4 Al 0.2 金属氢化物电极的电化学和氢传输动力学性能的温度依赖性。结果表明，温度对电极的一系列特性有显着影响。随着温度的升高，总电阻Rtotal(LP)和Rtotal(EIS)、极化电阻Rp和欧姆电阻Ro减小，而交换电流密度i 0 、对称因子β、极限电流密度iL和氢扩散系数D增大。在阳极极化下。活化过电势η a 和浓度过电势η c 随着温度的降低和放电电流密度的增大而增大。在较低的放电电流密度下，电荷转移是电极反应的速率决定步骤，而在较高的放电电流密度下，氢在电极主体中的扩散是速率控制步骤。在中等放电电流密度下，较低温度下电极反应主要由电极中氢的扩散决定，而较高温度下则主要由电荷转移控制。在中间温度下，电极反应受到电荷转移和氢扩散的混合控制。电极中电荷转移和氢扩散的活化能经计算分别为28.1和19.9 kJ mol -1 。
Temperature dependence of the electrochemical and hydrogen transport kinetic performance of MlNi 3.75 Co 0.65 Mn 0.4 Al 0.2 metal hydride electrode have been systematically investigated in the temperature range -20 to 85°C. The results show that temperature has pronounced effects on a series of characteristics of the electrode. With the increase of temperature, the total resistance R total (LP) and R total (EIS) , the polarization resistance R p , and the ohmic resistance R o decrease, while the exchange current density i 0 , the symmetry factor β, the limiting current density i L , and the hydrogen diffusion coefficient D increase. Under anodic polarization. the activation overpotential η a and the concentration overpotential η c increase with the decrease of temperature and with the increase of discharge current density. At lower discharge current densities, charge transfer is the rate-determining step of the electrode reaction, whereas at higher discharge current densities, the diffusion of hydrogen in the bulk of the electrode is the rate-controlling step. At medium discharge current densities, the electrode reaction is mainly determined by hydrogen diffusion in the electrode at lower temperatures, while it is mainly controlled by charge transfer at higher temperatures. At intermediate temperatures, the electrode reaction is under mixed control of charge transfer and hydrogen diffusion. The activation energy for charge transfer and for hydrogen diffusion in the electrode were calculated to be 28.1 and 19.9 kJ mol -1 , respectively.