On the role of inductive loops at low frequencies in PEM electrolysis

Abstract

Inductive loops at low frequencies have been observed in the electrochemical impedance spectra (EIS) of various electrochemical cells. Although different physicochemical models for this phenomenon have been suggested in many other applications, this topic has not been widely discussed in the field of proton exchange membrane (PEM) electrolysis.In this article, low-frequency inductive loops in PEM electrolysis cells and their impact on cell performance are analyzed. We show that this phenomenon is reproducible and occurs with different cell materials and setups. Its impact increases with increasing current density and decreasing temperature. At extreme conditions (7 A∙cm−2, 40 °C) we show that the negative polarization resistance of the inductive process can exceed the capacitive polarization processes by a factor of three, resulting in a direct current resistance less than the high frequency series resistance of the cell.

Keywords

• PEM electrolysis
• EIS
• Inductive loops
• Low frequency
• High current density
• Negative polarization resistance