The OCP -CV -OCP -EIS -CP (charge, discharge) -OCP -EIS experiment sequence was used for long-term testing of the REs in a ferrocene-containing electrolyte with SDC. OCP was used for the equilibration of the electrochemical cell. CV measurements were used for RE potential measurement against Fc/Fc + redox couple. EIS was used to track the changes in the electrode-electrolyte interphase. CP was used to analyze the charge and discharge behaviour of the WE. For other reproducibility experiments with a standard electrolyte without ferrocene, OCP -EIS -CP (charge, discharge) -OCP -EIS sequence was used.