Ionic Liquids as Green Electrolytes for Supercapacitors

The interest in supercapacitors, which are energy storage/conversion systems of high-power is growing world wide for applications ranging from transportation to stand-alone or grid-connected power plants. Various electrode and electrolyte materials and cell configurations are under study for the development of safe, high-energy supercapacitors without sacrificing power capability and cycling stability. Ionic liquids (ILs), for their inherent properties of high electrochemical and chemical stability, good conductivity, low vapor pressure and no flammability are excellent green-electrolytes for safe, high voltage, high specific energy supercapacitors. Supercapacitors working with ILs require cell configuration and electrode materials tailored in relation to the nature of the IL itself. Here, the performance of electrochemical double layer carbon supercapacitors operating with solvent-free IL is reported and the advances in terms of specific power and energy which are feasible by proper IL selection and by tuning carbon electrode pore geometry are discussed.