Enhanced Electric Double-Layer Capacitance by Desolvation of Lithium Ions in Confined Nanospaces of Microporous Carbon

Carbon electrodes with specific microporous structures are strongly desired to improve the performance of electric double-layer capacitors (EDLCs). We report solvated states of Li ions in confined carbon micropores affecting specific capacitance. The average Li+ solvation number of 1 M LiClO4/propylene carbonate (PC) electrolyte introduced into porous carbon electrodes was determined using Raman spectroscopy and 7Li NMR. Micropores with slightly larger pore size against the solvated molecules and the narrow two-dimensional spaces decreased the solvation number, enhancing specific capacitance. Hence, specific carbon morphology may be related to high EDL capacitance, and micropore structure is important in obtaining highly capacitive EDLC materials.