Generalized Electrochemical Impedance Spectroscopy (GEIS) in Solid State Ionics

Electrochemical Impedance Spectroscopy (EIS) is a widely applied tool in solid state ionics. It is used to analyze transport and adsorption processes as well as interfacial reactions for a large variety of electrochemical... [ view full abstract ]

Electrochemical Impedance Spectroscopy (EIS) is a widely applied tool in solid state ionics. It is used to analyze transport and adsorption processes as well as interfacial reactions for a large variety of electrochemical systems. Yet, there are elusive processes and intermediate reaction steps that cannot be identified just by analyzing the impedance of the system, defined as the transfer function between voltage and current.

I will show how additional quantities can be probed in order to gain more information about processes and characteristics of the electrochemical system. Replacing voltage or current, i. e. excitation or response signal, in an EIS measurement by another physical quantity such as illumination or temperature leads to so-called generalized electrochemical impedance spectroscopy (GEIS) measurements, that open up a whole new field of measurement techniques just recently receiving interest in the materials community. Such measurements can be applied in situ and provide a general transfer function capable of being analyzed with the tools readily available for evaluating EIS data. Another advantages of these frequency domain measurements is the signal quality because noise is effectively filtered out.

In this talk I give an overview of GEIS measurements such as: intensity modulated photocurrent/-voltage spectroscopy (IMPS/IMVS), optical impedance spectroscopy (OIS) and electro-thermal impedance spectroscopy (ETIS). Practical examples it will be provided that demonstrate the new insights that can be gained with the aid of GEIS. An overview of experimental setups will also be provided.

This work was supported by JSPS Core-to-Core Program, A. Advanced Research Networks.