Problems Associated With the Measurement of Electrode Properties

4 Problems Associated With the Measurement of Electrode Properties 

In the work discussed so far, the main objective was to characterize the bulk properties the electrodes were there only to make this measurement possible. In other 

On symmetrical cells equipped with two nominally identical electrodes, using a small ac signal, at zero dc polarization. In this case, the electrode polarization obtained from the impedance plot must be divided by two, since it is caused by the two electrodes in series. The measuranent is simple and can be performed with an impedance analyzer. 

On three-electrode cells, i.e. cells equipped with working electrode, counterelectrode, and reference electrode (WE, CE, and RE) under potentiostatic or galvanostatic control. In this case, the small ac signal is superimposed on a dc polarization. The measurement requires au electrochemical interface (potentiostat or galvanostat) coupled to an FRA (see Section 3.2). 

While the latter case offers greater flexibility, it is also susceptible to rather subtle errors, which arise from the positioning of the RE in relation to the WE. These errors need to be considered if reliable electrode performance is to be obtained on solid electrolyte cells. With liquid electrolytes, the RE cau be made as small as necessary and placed as close to the WE as required. With solids, the electrode must be located on the electrolyte surface, or, if the electrolyte thickuess permits, in a suitably fash- 

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