High energy and power density symmetric supercapacitors with ionic liquids electrolytes

Supercapacitors are high-power and fast-charge energy storage devices that store charge at the interface between porous carbon electrodes and an electrolyte solution. Since capacitors` energy content increases with the square of its voltage, the development of high energy supercapacitors heavily depends on the evaluation of high electrochemical window electrolytes. The emerging alternatives for supercapacitors are room-temperature ionic liquids (RTIL) and ultra-concentrated electrolytes, with operating voltages as high as 3.5V achievable [[1]]. However, the increase in energy comes at a price, as poorer device power performances and a high cost of the electrolyte. Our research efforts have culminated in the outstanding performance of supercapacitors with electrochemical window of 3V, the energy density of 30Wh/kg, power density of 14kW/kg (at 84% of the maximal energy), cycle life up to 70,000 cycles, improved safety, reduced environmental impact and commercially compatible device cost.

[1]. C. Zhong, Y. Deng, W. Hu et al., Chem. Soc. Rev. 21 (2015), 7431-7920