Electrochemical impedance spectroscopy stainless steel electrode

Gao et al. [60] reported the CV and electrochemical impedance spectroscopy of self-assembled, stainless steel supported s-BLMs, using a three-electrode system. The membrane resistance and capacitance calculated from the whole impedance spectrum rather than at certain frequencies were close to the conventional BLMs. The time course of impedance under certain applied frequencies was investigated. The results showed that the membrane capacitance of s-BLM fluctuated under low frequency and gradually reached a constant value with the increase in applied frequency. Fullerene-doped s-BLMs were demonstrated to intensify this fluctuation behavior of membrane capacitance. A possible mechanism of this peculiar property of s-BLMs under low frequencies is discussed in Ref. 43. 

The most common method of electrolytes examination is electrochemical impedance spectroscopy (EIS) with blocking (usually stainless steel) and/ or reversible electrodes (most often metallic lithium, or other metal, common with the salt used Saraswat et al. 1989). It allows determination of samples conductivity (Bauerle 1969), following the evolution of complete and half cells resistance upon storage (Sannier et al. 2007 Syzdek et al. 2007) sometimes it is used for transference number measurements (Ravn Sprensen and Jacobsen 1982), as well as a complementary technique in the studies on the crystallisation of solid electrolytes (Marzantowicz et al. 2006a,b,c, 2008), where detailed equivalent circuit considerations are applied. Another very important way of studying these systems is a set of DC techniques, i.e. voltammetry (Armand et al. 1980) and DC polarisation (chronoamperometry and chronopotentiometry). They allowed studies of the electrode reactions and examination of transport properties of electrolytes, especially transference number by Bruce and Vincent and co-workers (Bruce and Vincent 1987,1990 Bruce et al. 1987 Christie et al. 1999 Evans et al. 1987 MacCaUum et aL 1986) and/or Newman method (Doyle and Newman 1995 Hafezi and Newman 2000). 

Because of the resistance to ion flow at the electrode-electrolyte interface, normal measurement of total ionic conductivity is not possible in polymer electrolytes. In order to overcome this problem the conductivity measurements are carried out by the ac impedance spectroscopy method, which minimizes the effects of cell polarization. The measurements are often made with the electrolyte sandwiched between a pair of electrochemically inert electrodes made of platinum or stainless steel. The detailed methodology of impedance spectroscopy is reviewed thoroughly elsewhere [45-47]. 

Fig. 9.5 (a) Structures of the ionic liquids, (b) Photograph of gel polymer electrolyte with a diameter of 13 mm and a thickness of 200 pm. (c) Conductivity Arrhenius plots of four gel polymer membranes. The data are obtained from impedance spectroscopy at 10-50 °C. (d) Composition, conductivity data, and ECW of gel polymer electrolytes with varied ionic liquids, mp melting point, EON electrochemical window electrodes, stainless steel/stainless steel first cycle v = 25 mV/s T=50 °C potential range, E vs Stainless Steel= 4 V [57]... 

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