Electrochemical Impedance Spectroscopy Part 1: Fundamentals

Abstract

Electrochemical impedance spectroscopy (EIS) enables the examination of the electrochemical nature of electrodes and electrochemical cells by applying an alternating voltage (or current) and measuring the resulting current (or voltage). The resistance and capacitance components of the electrode can be evaluated by applying an AC voltage and changing the frequency. In particular, analysis using the equivalent circuit can determine important parameters related to the electrochemical reaction of the electrode, such as the charge transfer resistance, electric double-layer capacitance, and Warburg impedance. Moreover, the internal resistance of the cell can be divided into resistances caused by the positive electrode, negative electrode, and electrolyte. Because of these advantages, EIS is a powerful technique used for basic research, such as in identifying the rate-determining step of an electrochemical reaction, and also for applied research, such as characterizing electrochemical devices (e.g., batteries and capacitors). In this paper, the concept of impedance, which represents the relationship between the AC voltage and current, is first explained; then, the AC characteristics of various circuit elements used in equivalent circuits, which are essential for understanding EIS, are described. Finally, treatments of more complex circuits based on transmission-line models (TLMs), which are used to represent equivalent circuits of porous electrodes, are presented. Analyses based on TLMs are the foundation for understanding electrodes for practical applications because porous electrodes are usually used in electrochemical devices.

The new method of ZnIn2S4 synthesis on the titania nanotubes substrate with enhanced stability and photoelectrochemical performance

“…Figure S6 shows Nyquist plots for all the materials obtained. The spectra are typical for porous electrodes 52 . They are seen as straight, almost vertical lines as a characteristic of capacitive behavior.…”

Effect of Fluorine Substitution in Li₃YCl₆ Chloride Solid Electrolytes for All-solid-state Battery

“…Considering the lower binding energy of LiF compared to Li3YCl6 and LiCl, the 28 the high-frequency side can be assigned to the resistance from the solid electrolyte, and the low-frequency side is attributed to the charge-transfer resistance at the electrode/electrolyte interface. 25,31,32 Although almost no difference can be confirmed on the high-frequency side, Li3YCl5.97F0.03 has a lower charge-transfer resistance than Li3YCl6. Li3YCl5.97F0.03 suppresses the formation of a highly resistant decomposed product at the electrode/electrolyte interface, which improves the charge-discharge efficiency.…”

Electrochemical Impedance Analysis of Lithium Insertion Electrodes Using Symmetric Cells

“…The transmission-line model has been used to analyze the EIS of porous electrodes. 7,55,59 In this model, in addition to the charge-transfer resistance (R ct ) of each particle, the resistances related to electronic conduction (R e ) and ionic conduction (R ion ) should be considered for EIS. Figure 8 shows the simulated EIS results for porous electrodes with and without a charge-transfer reaction.…”

“…Electrochemical impedance spectroscopy (EIS), which enables the distinction of each component with respect to the frequency response, [4][5][6] is the most effective method for clarifying the resistance components of electrodes in LIBs. [7][8][9][10][11][12][13][14] Electrochemical measurements using a two-electrode cell provide only the internal resistance of the battery, which is the sum of the resistances of the positive and negative electrodes and the ohmic loss of the electrolyte. A three-electrode cell equipped with a reference electrode is typically used to examine the resistance of a single electrode.…”