Preparation and Electrochemical Properties of Fluorinated Mesoporous Carbon Foams for Electric Double-Layer Capacitors

Abstract

We reported the preparation and electrochemical properties of fluorinated mesoporous carbon foams (F-MCFs) for application as electric double-layer capacitors (EDLCs). By using fluorinated resol which was obtained from the polymerization of formaldehyde, phenol, and 3-fluorophenol as the carbon source and fluorin precursor, and triblock copolymer F127 as a template, F-MCFs were prepared through evaporation induced self-assembly strategy. The F-MCFs were characterized by N2 adsorption and desorption, transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS). The results indicate that the F-MCFs possess highly ordered mesostructure with a specific surface area of 675 m2/g, a uniform pore size of 2.2 nm and a pore volume of 0.12 cm3/g. The wettability of F-MCFs was investigated by contact angle analysis. The contact angle of F-MCFs for water is 111.5o, much lower than that of mesoporous carbon foams (MCFs) (141o), indicating that the surface wettability of F-MCFs is improved by the introduction of fluorin into the carbon matrix. The enhancement of wettability would increase the surface contact of electrolyte and electrode and accelerate the ion transfer within the pore channel, and thus improve the electrochemical properties of F-MCFs. The electrochemical properties of the F-MCFs have been investigated by cyclic voltammetry (CV) and galvanostatic charge/discharge in electrolyte of 6 mol/L KOH with a three-electrode system. F-MCFs present linear galvanostatic charge-discharge curve at a loading current of 10 mA, and possess good charge-discharge efficiency over 98%. The specific capacitance of the F-MCFs is 220 F/g, significantly higher than that of the MCFs (140 F/g). F-MCFs show important prospect as electrode materials for the application in EDLCs.