Research Progress of Solid-state Supercapacitors Electrolytes and Its Classifications

Electrochemical capacitors (also known as supercapacitors), as a kind of energy storage device with high power density, long cyclic life and excellent stability, has attracted more and more attentions in recent years. Solid-state or quasi-solid-state supercapacitors can be widely applied in flexible electronics, flexible energy storage devices, wearable devices, and other areas due to their excellent mechanical flexibility, low volatility and flammability, easy assembly and molding. We thus introduce the advantages and configurations of solid-state supercapacitors. The solid-state electrolytes, which include the polymer gel electrolytes and the inorganic solid-state electrolytes, are introduced respectively. According to the different solvents, polymer gel electrolytes can be divided into hydrogel electrolytes, organogel electrolytes,and ionogel electrolytes. Among them, hydrogel electrolytes have been widely investigated due to their superior biocompatibility and good electrochemical performance. The inorganic solid-state electrolytes have relatively poorer electrochemical performance compared to the polymer gel electrolytes, they still play an important role in some specific areas such as satellite electronics because of the bone dry property. Lastly, different types and the characteristics of redox additives in solid-state electrolytes are introduced. It is noticed that the inorganic redox additive is a good option to increase the energy density as well as the power density of solid-state supercapacitors. © 2019, High Voltage Engineering Editorial Department of CEPRI. All right reserved.