Equivalent series resistance polymers

The equivalent series resistance (ESR) and equivalent series inductance (ESL) of the output capacitor substantially control the output ripple. Use an output capacitor with low ESR and ESL. Surface mount Tantalums, surface mount polymer electrolytic and polymer electrolytic and polymer Tantalum, Sanyo OS-CON, or multilayer ceramic capacitors are recommended. Electrolytic capacitors are not... 

In attempts to improve capacitance over that achieved to date in polymer-based supercapacitors, several groups have investigated EAP-based composites based on PPy [170,173-175], PANI [78,176-178], PT [160,179], PMT [166], and PFPT [160,180,181]. By using a combination of an EAP electrode and an activated carbon electrode, it is possible to produce devices with higher specific power than double-layer capacitors due to the lower equivalent series resistance [166]. In some cases, composite electrodes are a matter of necessity when chemical polymerization is used to produce insoluble polymer powders, the powders can be blended with carbonaceous material and binder. 

Fig. 7 (a) Lumped circuit model approximation of transport described by the diffusion equation. Such a response can be the result of concentration gradients or combined ionic resistance and distributed capacitance, (b) Example of an equivalent circuit model including a finite diffusion element, a series resistance, and capacitance at the interface between the solution and the polymer... 

In summary, two processes should be considered as indicated above when the polymer is reduced and can be represented by the equivalent circuit of Figure 3a. In this diagram, represents the solution resistance, Q refers to the double layer capacitance, Ri is the intrinsic resistance due to charge transfer of the redox process within the polymer film, W is the equivalent to the ionic diffiision at the film/electrolyte interphase, Q is the film capacitance, and Rf is the film resistance. In all cases, an electronic resistance component of the polymer film is considered to be connected in series with the solution resistance. Similar equivalent circuits were described in the literature for poly(2,5-di-(-2-thi yl)-thiophene) films earlier in the literature (25). The value of e electrical r istance of the polymer film varies considerably according to the applied potential to the polymer film, the film thickness and the electrol3rtic medium in which the measurement is taking place (26). Polymer film parameters are summarized in Table 1 for both oxidized and reduced states, respectively. 

We extend the analysis and consider the entire ladder network in terms of distinct R and C circuit elements. The impedance x can be represented by a resistance Ri, which defined the resistance of counterions in the pore electrolyte. Furthermore the impedance element z, which is that of the solid polymer, is replaced by a Randles equivalent circuit (see Fig. 1.84), where there is a parallel arrangement of a resistor Rj. and a capacitor Q in series with a resistor Ra- Hence we see that the pore solution is modeled in terms of a simple resistor, whereas the solid polymer is a binary composite medium. TTie latter assumption can be justified as follows. From a macroscopic viewpoint (and this has been demonstrated experimentally), the electronic resistance of the polymer is due to two contributions the first, Ra, from regions of high structural order the second, R, from regions of low structural order. Hence Ra is smaller than R. From a microscopic point of view, the polymer may exhibit two fundamentally different types of conduction. As noted in... 

Several additional physical processes potentially exist that can create somewhat more complicated equivalent circuit diagrams, as is evident for example from discussions in Chapter 10 on conductive polymer films. For instance, additional macrodefect corrosion and diffusion effects may develop between the coating and the surface, with an additional low frequency relaxation becoming visible in the Nyquist plot. The interface between a pocket of solution and the bare metal is modeled as a double-layer capacitance in parallel with a kinetically controlled charge-transfer resistance R, which can also often include the diffusion element associated with corrosion products in series with R. If the diffusion element represents a finite diffusion, an additional Rpiipp I element appears and a third relaxation at low frequencies,... 

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