Bounded Randles cell

The following model is a bounded Randles cell also accounting for a linear but finite diffusion, with a homogeneous layer of finite thickness. The structure of the model is shown in Figure 4.18a. The corresponding impedance is... 

The complex-plane impedance diagram of the bounded Randles cell is given in Figure 4.186. In this example, the parameters of the forward and backward reactions and diffusion coefficients are assumed to be equal. Impedance diagrams with variations in the parameters are presented in Appendix D (Model D17). 

The Nyquist plot is presented in Figure 4.9b. At high frequencies (real axis at a value of R. At low frequencies ( 0), it intercepts the real axis at a value of R+R0. Note that the bounded Warburg impedance is easily recognized from its Nyquist plot. At high frequencies, this circuit element looks like a traditional Warburg impedance and shows a 45° line on the Nyquist plot. At low frequencies, it looks like the semicircle of a Randles cell,... 

Figure 4.20. a Equivalent circuit of modified Randles cell with bounded CPE in series with Rc, (Model D19) b Nyquist plot of modified Randles cell having a bounded CPE in series with Rc, over the frequency range 6 kHz to 1 mHz (Model D19 Rei = 10 2, Rcl = 20 Q, R0 =... 

Figure D.56. Modified Randles cell with a bounded Warburg in series with Rct (Figure 4.18a)...

Figure D.57. Nyquist plot of modified Randles cell with a bounded Warburg element over the frequency range 1 MHz to 1 mHz (Rel = 50 Q, Rct = 100 Q,, Cjj = 0.00001 F,...

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