March 10-14, 2019
There are two common methods to measure the impedance response of only one electrode of a solid-state electrochemical cell, microelectrodes or a three-terminal configuration. In aqueous electrochemistry, three-terminal configurations are widely used, however, implementing this method in solid-state electrochemistry is highly non-trivial. This work summarizes, which method is most suitable for different applications. We show potential error sources and evaluate each of them quantitatively with special emphasis on their impact in thin film electrode measurements. Evaluation is done by means of finite elements analysis (FEA), electric circuit simulations and conducted measurements.
Three potential error sources were identified as particularly crucial factors: (i) Asymmetric sample cells (ii) short circuit currents across the reference electrode (RE), (iii) Especially for highly resistive electrode, coupling capacitances between the three electrodes.
These error sources can result in different measurement errors such as additional high frequency semicircles, additional low frequency semicircles, inductive loops and even more critical, erroneous electrode properties without indicating of additional features in the impedance spectrum.
We propose a novel sample geometry, the “wing geometry”, which was designed to minimize the measurement errors significantly, but still remains affordable and suitable for different applications.
Tobias Huber, Richard Schlesinger, Markus Kubicek, Jürgen Fleig, and Alexander Schmid, "3-point measurement in solid state devices: (Novel) artifacts and how to avoid them" in "Nonstoichiometric Compounds VII", ECI Symposium Series, (2019). https://dc.engconfintl.org/nonstoichiometric_vii/8