Accurate measurement of internal resistance in microbial fuel cells by improved scanning electrochemical impedance spectroscopy

In this study, a scanning electrochemical impedance spectroscopy (EIS) technique is proposed to confirm the variation of internal resistance (R-int) including charge transfer resistance (R-ct) and ohmic resistance (R-ohm) under various working conditions of microbial fuel cells (MFCs). In order to establish a scanning EIS method, overall R-int of the system and R-ct of anode and cathode were measured by EIS under various external resistance conditions. Using this method, it was confirmed that the R-ohm and R-ct of each electrode changed variably. Based on the use of scanning EIS, the rapid increase in the R-ct of anode was found to be the main cause of a power-overshoot. As such, the use of scanning EIS is a methodology that can provide data to understand undesirable phenomena such as power-overshoot and voltage reversal which are generated by the typical operational characteristics of MFCs when used in scale up experiments. The use of scanning EIS should be applied as a novel measurement technique that improves on the use of the open circuit mode based EIS methods (c) 2020 Elsevier Ltd. All rights reserved.

Automated summary

The scanning electrochemical impedance spectroscopy (EIS) technique can be used to confirm the variation of internal resistance in microbial fuel cells (MFCs) under different working conditions, including charge transfer resistance and ohmic resistance. By measuring the overall internal resistance of the system and the charge transfer resistance of the anode and cathode using the scanning EIS method, it was found that the resistances of each electrode changed variably. This method revealed that the rapid increase in the anode's charge transfer resistance was the main cause of power overshoot, providing valuable insights for understanding undesirable phenomena in MFCs.