Using Polymeric Ionic Liquids as an Active Binder in Supercapacitors

Electrodes in batteries and supercapacitors generally contain inert binders to maintain their structural integrity during operation but do not participate in the storage of energy. In this paper, we demonstrate that poly ionic liquids can function as structural binders while simultaneously improving the energy storage capability of supercapacitors. Specifically, we show that when the ionic liquid N-butyl-N-methyl pyrrolidinium bis(trifluoromethanesulfonyl)imide is used as electrolyte and poly(diallyldimethylammonium) bis(trifluoromethanesulfonyl)imide is employed as electrode binder the permissible operating voltage of the device is enhanced to 4.0 V. This results in a substantially increased overall specific energy (80% greater) and represents a step toward the development of devices with long cycle lives and high energy densities.