Basics of teaching electrochemical impedance spectroscopy of electrolytes for ion-rechargeable batteries – part 2: dielectric response of (non-) polymer electrolytes

Suhaila Idayu Abdul Halim,Jan Apotheker,Chin Han Chan

doi:10.1515/cti-2020-0018

Suhaila Idayu Abdul Halim, Jan Apotheker + Show 1 more

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https://doi.org/10.1515/cti-2020-0018

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Abstract

Abstract In the Part 2 of this article, we present the phenomenological response of the dielectric relaxation for polymer electrolytes monitored by electrochemical impedance spectroscopy (EIS) in terms of electrochemical point of view, such as impedance (Z*), permittivity (ε*), loss tangent (tan δ), modulus (M*) and conductivity (σ*) spectra. It is noteworthy to note that all the electrochemical aspects mentioned are of interest for conduction and seen as closely related to each other indirectly or directly. Two different systems; solid polymer electrolyte (SPE) [poly(ethylene oxide) (PEO) + lithium perchlorate (LiClO4)] and non-SPE [poly(methyl acrylate) (PMA) + LiClO4] were employed for discussion. EIS is a powerful technique to characterize the electrical properties of polymer electrolytes. The results suggest that impedance and modulus are of interest for decoupling of dielectric and electric properties by evaluating the short-range and long-range mobility of the charged entities, respectively. One is able to identify the conduction mechanism of the polymer electrolytes easily if the responses are well understood. The objective of this article to introduce a simplified yet an insightful background and technique that is easy to be followed and useful for educational purposes especially for beginners or young researchers for both undergraduates and postgraduates.

Highlights

The basics of electrolytes, electrochemical impedance spectroscopy (EIS) instrumentation and some fundamental background on electrolytes and batteries were elucidated in the Part 1 of this article
In the Part 2 of this article, we present the phenomenological response of the dielectric relaxation for polymer electrolytes monitored by electrochemical impedance spectroscopy (EIS) in terms of electrochemical point of view, such as impedance (Z*), permittivity (ε*), loss tangent, modulus (M*) and conductivity (σ*) spectra
We note the double-logarithmic plot of impedance spectra presented in Figure 1(a) as: – Both poly(ethylene oxide) (PEO)-LiClO4 systems have an average maximum resonance in Z′′ spectrum at certain frequency region noted as fmZ′′ax, this is as a result from the relaxation of dipolar entities

Summary

Introduction

The basics of electrolytes, electrochemical impedance spectroscopy (EIS) instrumentation and some fundamental background on electrolytes and batteries were elucidated in the Part 1 of this article. The emphasis of the following discussion is on the response of the charged entities in the solid polymer electrolytes (i.e. SPE: PEO-LiClO4 and non-SPE: PMA-LiClO4) under the effect of oscillating electric field in classical sense (i.e. to decouple the short-range and long-range dielectric relaxation resulting from local or non-local motion of the charged entities).

Results

Conclusion