Polymer and carbon materials in safe, high-energy supercapacitors operating with ionic liquids

Much attention is being focused on electrode and electrolyte materials for supercapacitors which are energy storage/conversion systems of high-power for applications ranging from transportation to stand-alone or grid connected stationary power plants. Safety in operation regimes above room temperature is one of the main concerns and ionic liquids (ILs) of high thermal stability and low vapour pressure are under study as solvent-free, safe electrolytes. Furthermore, the wide electrochemical stability window of the ILs permits high cell voltage, thus they can be used to develop high energy supercapacitors without penalty in power capability. To this aim various chemistries and cell configurations are considered and this presentation discusses the characteristics of ILs and polymer and carbon electrode materials that allow the development of supercapacitors of high-energy. The performance over several thousand cycles above room temperature of hybrid and asymmetric supercapacitors with pyrrolidinium-based ILs and properly designed electrode materials are given in terms of maximum reached cell voltage, specific capacitance and specific energy.