New types of supercapacitors

Supercapacitors of high specific power play a crucial role in the development of electric vehicles where they can be coupled with lithium batteries or fuel cells to provide power peaks during acceleration as well as for energy recovery during braking. The typical operating temperature for these applications are higher than RT. Thus, in order to develop high voltage supercapacitors operating above RT we are pursuing the strategy of using ionic liquids (ILs) solvent-free” electrolytes of high thermal stability, wide electrochemical stability window and good conductivity. We already demonstrated the viability of this strategy in activated carbon (AC) // poly(3-methylthiophene) (pMeT) hybrid supercapacitors: when a high purity and hydrophobic IL such as N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide was used these supercapacitors provided maximum cell voltages higher than 3.4V as well as long cycling stability over 15,000 cycles at 60 °C. Furthermore, this very interesting result was achieved with commercial electrode materials and we demonstrated that improvements of such IL-based hybrid supercapacitors are feasible via optimization of the affinity of electrode materials for the ILs. Here we present and discuss results on the development of materials with morphologies and surface chemistry tailored for operation at 60°C in hydrophobic ILs. Particularly, data on mesoporous cryogel carbons and pMeT synthesized in the frame of the ILHYPOS “Ionic Liquid-based Hybrid Power Supercapacitors” UE Project are reported and discussed.