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

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.