Characterization of Ag/Ag2SO4 system as reference electrode for in-situ electrochemical studies of advanced aqueous supercapacitors

Abstract

Silver metal covered by Ag2SO4 was investigated as a reference electrode for flat three-electrode cells. The potential stability of the Ag/Ag2SO4 electrode in neutral aqueous solutions utilized as electrolytes for asymmetric high-voltage supercapacitors is reported. It was found that the potential drift and temperature coefficient of this reference electrode are insignificant. Its use as an alternative to the Ag/AgCl electrode enables one to avoid the contamination of the supporting electrolyte solution by Cl − anions, which are oxidized earlier than water molecules and other oxygen-containing anions (SO42− or NO3−). Using the data obtained from three-electrode electrochemical measurements with the electrode in question, a graphene–carbon nanotube/MnO 2 supercapacitor cell accumulating 9.8 Wh kg −1 of specific energy at 1.75 V was built. [Figure not available: see fulltext.]