Conventional supercapacitor electrolytes: aqueous, organic, and ionic

This chapter thoroughly covers the most recent developments of aqueous and nonaqueous electrolytes for electrochemical supercapacitors (SCs). In more detail, the overview of different types of electrolytes and their featured properties are initially introduced. Thereafter, the conventional aqueous electrolyte is discussed and summarized, and the perspectives of some new salts that can be used to enhance the ionic conductivity and the performance of the SC are also presented. Organic electrolytes, including organic solvents/salt, ionic liquids, and deep eutectic, are the main areas to explore different trends and cutting-edge advances in optimizing electrolyte formulations customized for different electrode materials. Furthermore, the current obstacles and prospects of these electrolytes are also underlined.