Analysis of electrochemical impedance spectra in the context of polymer electrolyte membrane water electrolysis

Abstract

The working of a Polymer Electrolyte Membrane (PEM) electrolysis cell is discussed and a graphical representation analysis of the equivalent circuit impedance is carried out. This helps to provide a comprehensive grasp on the fundamentals and on the factors affecting the changes in the electrochemical impedance spectra. The polarization curve of an electrolysis cell is essential for understanding these variations. Furthermore, an experiment is done on a PEM electrolysis cell at 80°C with a Nafion 117 membrane and data was collected after 50 h and after 500 h of operation for different current densities. The knowledge gained from the initial analysis of the electrolysis cell is employed to explain the impedance spectra obtained from the experiment. The conclusions derived are then used for the formulation of correction factors to obtain the modified parameters of the electrolysis cell equivalent circuit which could prove useful in the long run in reducing the challenges faced while working with PEM electrolysis cells.