Material characteristics for safe, high-energy supercapacitors

The interest in supercapacitors, which are energy storage/conversion systems of high-power for applications ranging from transportation to stand-alone or grid connected stationary power plants, is world wide growing. Various chemistries and cell configurations are under study for the development of safe, high-energy supercapacitors with minimum penalty in power capability. This presentation discusses the characteristics of electrode and electrolyte materials that allow to reach this goal, particularly of carbonaceous and polymer electrode materials and of ionic liquids (ILs) that for their low vapour pressure and high thermal stability are receiving much interest as safe electrolytes for supercapacitors operating above room temperature. The wide electrochemical stability window of ILs permits to attain high cell voltage, which is a powerful strategy for the energy increase, provided that suitable cell configurations, hybrid or asymmetric, are used. Results of the study on the selection and development of electrode materials in relation to the nature of the IL, which in turn affects their capacitive responses, and thus the capacitance and energy of the supercapacitors, are reported and discussed