Effects of Ionic Liquids Confined in Carbon Nanopores with Different Geometries and Surface Charges

During the presentation an important role of nanopores having different geometries and various surface charges on the nanoconfinement of ionic liquids utilized to assembly the electric double-layer capacitors (EDLCs) operating at sub-zero temperatures will be discussed. Home-made carbons were prepared via different methods of templated synthesis, while a pristine imidazolium-based fluorinated ionic liquids and their binary mixture were used as a solvent-free electrolyte. It will be shown that short-range graphene layers produced with 8-nm silica nanoparticles lead to the creation of transport channels which better accommodate ions. We explain these findings per coulombic interactions among the ions and between the pore wall and the ionic species under confinement and electrochemical polarization conditions. Further, it will be shown that a microporous carbon performs better than hierarchical carbons at room temperature; however, owing to the large fraction of mesopores, the latter exhibit far higher capacitance down to −40 °C. While the ordering of ions in confinement is more critical at room temperature and dictated by the micropores, low temperature performance of supercapacitors is determined by the mesopores that provide channels for facile ion movement and keep the bulk ionic liquid–like properties.