Activation energy polarization resistance

An -> ideal nonpolarizable electrode is one whose potential does not change as current flows in the cell. Much more useful in electrochemistry are the electrodes that change their potential in a wide potential window (in the absence of a - depolarizer) without the passage of significant current. They are called -> ideally polarized electrodes. Current-potential curves, particularly those obtained under steady-state conditions (see -> Tafel plot) are often called polarization curves. In the -> corrosion measurements the ratio of AE/AI in the polarization curve is called the polarization resistance. If during the -> electrode processes the overpotential is related to the -> diffusional transport of the depolarizer we talk about the concentration polarization. If the electrode process requires an -> activation energy, the appropriate overpotential and activation polarization appear. 

Despite the rather low ionic conductivity and, hence, the poor utilization of the bulk path, porous LSM cathodes show acceptable polarization resistances in zirconia-based SOFCs at 1000°C. However, the activation energy of the polarization resistance is rather high (ca. 1.8-2.1 eV [94, 95, 119, 120, 131, 132]) and the trend to lower the operation temperature of fuel cells requires... 

NOTE AE, activation energy ER, electrical resistance EIS, electrochemical impedance spectroscopy EN, electrochemical noise LPR, linear polarization resistance. 

Fig. 13.7. Graphical representation of the influence of the internal resistance of an electrochemical energy converter on the cell potential when mass-transfer polarization is negligible. The early nonlinear part of the curve represents the effect of the activation overpotential on the cell potential before ohmic polarization has become important.

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