Precautions for good impedance measurements (EIS) – Electrochemistry & Battery- Application Note 5Latest updated: August 26, 2021
A complete measurement setup consists of the sample under study, Bio-Logic potentiostat-galvanostat-ZRA and, what is often forgotten, the connection between the two. The laws of electromagnetism warrant stray capacitances of cell connections, self-inductance of any sort of a wire, as well as noise pick-up in any unshielded or unguarded cable. Those stray contributions tend to be strong both at high and low frequencies (ZL=jwL, ZC=1/jwC). Particularly often observed and easy to prevent is a pickup of the 50/60Hz power line frequency. Inductive contributions tend to be more visible at high currents, while capacitive contributions often obstruct very low current measurements. Being aware of those factors and applying certain precautions allows for avoiding/minimizing these artifacts and increasing data quality using the same hardware.
From biological cell analysis to fuel cell tests, from coatings to cement paste quality control, Electrochemical Impedance Spectroscopy (EIS) has become a powerful tool in the vast environment of electrochemistry. EIS is a non-intrusive and highly sensitive technique, but basic precautions, which are often overlooked, are needed to achieve error-free results. This document aims to highlight the nature of error sources placed outside the electrochemical cell and their effects in the study of electrochemical systems with the EIS technique placing an emphasis on high and low impedance cells. General conditions for accurate measurements relative to the sample linearity, causality, time independence, and stability are beyond the scope of this note
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