Equivalent model of electrochemical cell inc. ref. electrode impedance and potentiostat parasitics – Battery – Application Note 44

Abstract

As a highly sensitive technique, the electrochemical impedance spectroscopy (EIS) requires basic precautions to obtain reliable results. High impedance cells are more sensitive to capacitive artifacts while the low impedance cells are more sensitive to inductive and resistive artifacts.
Artifacts are even more important as the frequency of analysis now tends to cross the megahertz boundary. Ignoring these artifacts can lead to misinterpretation of the results. In this application note, we focus on the influence of stray capacitances introduced by the instrumentation. We also show that the strange results data obtained with a poor reference electrode can be perfectly explained by a complete model of the cell that includes the instrumental artifacts. Reducing the reference electrode’s impedance can be a straightforward method to minimize instrumentation artifacts coming from the reference electrode. As a general precaution, special care must be taken with the reference electrode to ensure accurate impedance measurements at high frequencies.

Introduction

As a non-intrusive and highly sensitive technique, the electrochemical impedance spectroscopy (EIS) requires basic precautions, often overlooked or ignored, to obtain reliable results. High impedance cells are more sensitive to capacitive artifacts while the low impedance cells are more sensitive to inductive and resistive artifacts. Artifacts are even more important as the frequency of analysis now tends to cross the megahertz boundary. Ignoring these artifacts can lead to misinterpretation of the results. In this note, we focus on the influence of stray capacitances introduced by the instrumentation. We also show that the strange results data obtained with a poor reference electrode can be perfectly explained by a complete model of the cell that includes the instrument artifacts.

To view the entire application note please click the download button below.