This review describes recent advances in electrochemical impedance spectroscopy (EIS) with an emphasis on its novel applications to various electrochemistry-related problems. Section 1 discusses the development of new EIS techniques to reduce measurement time. For this purpose, various forms of multisine EIS techniques were first developed via a noise signal synthesized by mixing ac waves of various frequencies, followed by fast Fourier transform of the signal and the resulting current. Subsequently, an entirely new concept was introduced in which true white noise was used as an excitation source, followed by Fourier transform of both excitation and response signals. Section 2 describes novel applications of the newly developed techniques to time-resolved impedance measurements as well as to impedance imaging. Section 3 is devoted to recent applications of EIS techniques, specifically traditional measurements in various fields with a special emphasis on biosensor detections.

Electrochemical Impedance Spectroscopy

Electrochemical impedance spectroscopy has become a mature and well-understood technique. It is now possible to acquire, validate, and quantitatively interpret the experimental impedances. This chapter has been addressed to understanding the fundamental processes of diffusion and faradaic reaction at electrodes. However, the most difficult problem in EIS is modeling the electrode processes, which is where most of the problems and errors arise. There is an almost infinite variety of different reactions and interfaces that can be studied (corrosion, coatings, conducting polymers, batteries and fuel cells, semiconductors, electrocatalytic reactions, chemical reactions coupled with faradaic processes, etc.) and the main effort is now being applied to understanding and analyzing these processes. These applications will be the subject of a second review in a forthcoming volume in this series.

Electrochemical Impedance Spectroscopy and its Applications

Reflections on the history of electrochemical impedance spectroscopy

Application of electrochemical impedance spectroscopy to study the degradation of polymer-coated metals

A critical overview of the latest developments in the aluminum battery technologies is reported. The substitution of lithium with alternative metal anodes characterized by lower cost and higher abundance is nowadays one of the most widely explored paths to reduce the cost of electrochemical storage systems and enable long-term sustainability. Aluminum based secondary batteries could be a viable alternative to the present Li-ion technology because of their high volumetric capacity (8040 mAh cm(-3) for Al vs 2046 mAh cm(-3) for Li). Additionally, the low cost aluminum makes these batteries appealing for large-scale electrical energy storage. Here, we describe the evolution of the various aluminum systems, starting from those based on aqueous electrolytes to, in more details, those based on non-aqueous electrolytes. Particular attention has been dedicated to the latest development of electrolytic media characterized by low reactivity towards other cell components. The attention is then focused on electrode materials enabling the reversible aluminum intercalation-deintercalation process. Finally, we touch on the topic of high-capacity aluminum-sulfur batteries, attempting to forecast their chances to reach the status of practical energy storage systems.

An Overview and Future Perspectives of Aluminum Batteries

Applications of Kramers—Kronig transforms in the analysis of electrochemical impedance data—III. Stability and linearity

Algorithms have been developed to apply the Kramers-Kronig transforms in the analysis of experimental electrochemical impedance data. The application of these algorithms is illustrated by transforming calculated impedance data for an electrical equivalent circuit, by transforming experimental data for TiO/sub 2-/coated carbon steel in HCl/KCl solution at 25/sup 0/C, and by analyzing data for an aluminum alloy in 4M KOH at 60/sup 0/C. These transforms, coupled with statistical techniques, provide a powerful means of evaluating the validity of impedance data with respect to spurious errors that are present in either the real or imaginary component, and with respect to system stability.

Application of Kramers‐Kronig Transforms in the Analysis of Electrochemical Impedance Data II . Transformations in the Complex Plane

An electrochemical impedance analysis of pure aluminum in at 25°C is reported. Impedance spectra have been obtained at 30–80 mV intervals extending from the hydrogen evolution region at −1.96V (vs. , ) to the transpassive dissolution region at −1.35V. The impedance spectra are found to consist of two intersecting capacitive semicircles with a loop at intermediate frequencies. The low‐frequency capacitive arc and the loop become increasingly dominant with respect to the high‐frequency relaxation as the potential is shifted in the positive direction. The impedance spectra and the steady‐state current/voltage characteristics (including the partial anodic and cathodic curves) are accounted for by a model involving the stepwise addition of hydroxyl groups to surface aluminum atoms, culminating in the chemical dissolution of to form . This anodic process is coupled to hydrogen evolution via competition for bare surface sites. Comparison of the experimental and predicted impedance spectra indicate that the total concentration of reactive sites at the surface varies with potential in a manner that parallels the anodic partial current. This variation is attributed to the existence of a porous corrosion product film on the surface. The impedance analysis also indicates small values (<0.1) for the transfer coefficients for elementary charge transfer reactions; these are attributed to the highly asymmetric nature of the reaction coordinate for reactions involving reactive species or to strong repulsive interaction between adsorbed species, as embodied in the Temkin adsorption isotherm.

Evaluation of Alloy Anodes for Aluminum‐Air Batteries IV . Electrochemical Impedance Analysis of Pure Aluminum in at 25°C

Evaluation of alloy anodes for aluminum-air batteries. III: Mechanisms of activation, passivation, and hydrogen evolution

The design, calibration, and operation of a source/collector electrochemical cell for delineating anodic and cathodic partial currents for reactive metals in aqueous media is described. This cell has been used to measure the hydrogen evolution current on aluminum and aluminum alloys in 4M KOH at 25/sup 0/, 50/sup 0/, and 80/sup 0/C over a wide range of potential. These data were then combined with the total current to calculate the anodic partial current as a function of potential. The data show that aluminum is a passive metal in 4M KOH at 25/sup 0/ and 50/sup 0/C, but that at 80/sup 0/C it undergoes transpassive dissolution over the entire potential range that is accessible.

Silvia Real

Papers

Applications of Kramers—Kronig transforms in the analysis of electrochemical impedance data—III. Stability and linearity

Application of Kramers‐Kronig Transforms in the Analysis of Electrochemical Impedance Data II . Transformations in the Complex Plane

Evaluation of Alloy Anodes for Aluminum‐Air Batteries IV . Electrochemical Impedance Analysis of Pure Aluminum in at 25°C

Evaluation of alloy anodes for aluminum-air batteries. III: Mechanisms of activation, passivation, and hydrogen evolution

Evaluation of Alloy Anodes for Aluminum‐Air Batteries II . Delineation of Anodic and Cathodic Partial Reactions