Experimental and theoretical cyclic voltammograms for electronically conducting polypyrrole film are obtained from the identical conditions and compared to each other to characterize electrochemical behavior of the polymer. A comparison of the simulated and experimental cyclic voltammograms shows quantitative agreement. The profiles of the dependent variables show that the switching process is governed by the availability of the counterion to the polypyrrole electrode and the amount of electroactive sites. Sensitivity analysis shows that the double layer effects have more influence in the cyclic voltammograms than the electrokinetic effects.
Polypyrrole is an attractive polymer for use as a high energy density secondary battery because of its potential as an inexpensive, lightweight, and noncorrosive electrode material. A mathematical model to simulate cyclic voltammograms for polypyrrole is presented here. The model is for a conductive porous electrode film on a rotating disk electrode (RDE) and is used to predict the spatial and time dependence of concentration, overpotential, and stored charge profiles within a polypyrrole film. The model includes both faradaic and capacitive charge components in the total current density expression.
A mathematical model to simulate the charge/discharge behavior of a lithium/lithium perchlorate‐propylene carbonate/polypyrrole false(normalLi/LiClO4‐PC/normalPPyfalse) secondary battery cell is presented. The model can be used to gain a better understanding of the behavior of this cell and to provide guidance toward the design of new secondary batteries which utilize an electronically conductive polymer such as polypyrrole (PPy) as the cathode. The model includes the capability of handling charge and discharge behavior and is used to study the effect of various design parameters on the performance of the cell.
In order to increase the specific capacitance and energy density of supercapacitors, non-aqueous supercapacitors were prepared using lithium transition-metal oxides and activated carbons as active materials. The electrochemical properties were analyzed in terms of the content of lithium transition-metal oxides. The results of cyclic voltammetry and ACimpedance analyses showed that the pseudocapacitance may stem from the synergistic contributions of capacitive and faradic effects; the former is due to the electric double layer which is prepared in the interface of activated carbon and organic electrolyte, and the latter is due to the intercalation of lithium (Li + ) ions. The specific capacitance and energy density of a supercapacitor improved as the lithium transition-metal oxides content increased, showing 60% increase compared to those of supercapacitor using a pure activated carbon positive electrode.Key Words: Lithium transition-metal oxide, Supercapacitor, Intercalation, Non-aqueous electrolyte, Energy density IntroductionInterest in supercapacitors as a main or a sub-power source for various applications requiring high power density such as electric vehicles, UPS systems and windmills has increased. 1-2The use of supercapacitors in the applications described above is thus far insufficient because the energy density is only one tenth of that in a secondary battery.Therefore, many researchers have investigated methods to improve the working voltage, specific capacitance, and energy density of supercapacitors. In an effort to improve the working voltage of supercapacitors, researchers have attempted to prevent or reduce electrochemical reactions between the electrodes and electrolyte interfaces; i.e., they have researched methods of removing functional groups of activated carbons.A considerable amount of research has been devoted in this area to increasing the specific capacitance and energy density. Different studies have attempted to enlarge the effective surface area of activated carbon or have prepared composite electrodes via an addition of transition metal oxides or conducting polymers.2-4 Obtaining large surface areas through ordinary methods increased the surface areas of micro-pores by only 20 Å or less. However, on such surfaces, it was difficult for the electrolyte to penetrate into the micro-pores. Thus, these micro-pores did not successfully improve the specific capacitance or energy density. 5Recently, to solve those problems, new approaches, collectively known as composite activation methods, have been attempted. These methods involve chemical activation and electrochemical activation. Chemical activation is carried out with potassium hydroxide or vapor in which electrochemically injected ions of a particular size are subsequently used to obtain more meso-pores (20 ~ 500 Å) and fewer micro-pores. 6 Another approach to increase the specific capacitance and energy density involves the use of the transition metal oxides such as ruthenium oxide (RuO 2 ), cobalt oxide (Co 3 O 4 ), and nickel oxide (...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.