Abstract:

Hybrid supercapacitors are energy-storage devices with great potential, they typically have high specific power, high cycle stability, high safety and relatively high specific energy, but the aqueous and organic electrolytes they use often suffer from drawbacks such as narrow electrochemical window and high flammability. In the meantime, the unique features of ionic liquids, such as low vapor pressure, non-flammability and wide electrochemical window make them ideal electrolytes for hybrid supercapacitors. This paper reviews the recent applications of ionic liquids in hybrid supercapacitors, including ionic liquids as pure electrolytes, components for mixture electrolytes, solid electrolytes and electrodes. Finally, it is pointed out that future research directions for ionic liquids in hybrid supercapacitor system is to improve its moisture stability and cutting down the cost of preparation. Due to the misunderstandings about the notion of hybrid supercapacitor and asymmetric supercapacitor, there has been many inappropriate descriptions about them. In this paper we try to explain the difference between the above-mentioned two kinds of supercapacitors.

Key words: ionic liquid, hybrid supercapacitor, asymmetric supercapacitor