Recent Progress in Electrolyte Systems for Supercapacitors
Masashi Ishikawa, Kaoru Dokko, Hsisheng Teng, Simon Lindberg, Jon Ajuria, Andrea Balducci, Elżbieta Frąckowiak
Abstract
Aqueous electrolytes containing sulfuric acid and organic electrolytes made by dissolving quaternary ammonium salts in propylene carbonate have long been used as electrolytes in supercapacitors. In the organic electrolyte system, acetonitrile was later also used as a solvent. This paper will describe more recent electrolytes for supercapacitors, including those in the research and development stage. The main electrolytes discussed here are novel-solvent-based electrolytes, highly concentrated electrolytes, deep eutectic electrolytes, polymer gel electrolytes, and solid-state electrolytes. The advantages as well as problems of these electrolytes are discussed, and the prospects of electrolytes for supercapacitors are presented.