Synthesis of Nanostructured Carbon and Sulfonated Polysulfone Ionomer for Solid-State Supercapacitors

An ordered mesoporous carbon material has been synthesized and used together with solid polymer electrolyte (SPE) to realize a solid-state supercapacitor (SC). The synthesis of carbon consisted in the preliminary preparation of highly ordered mesoporous silica (SBA-15), used as a template material, that in a second step was impregnated with sucrose that after thermal treatment at 850 °C was transformed in carbon. The so prepared carbon is know as CMK-3 type carbon. The solid polymer electrolyte was synthesized using trimethyl silyl chlorosulfonate as sulfonating agent in homogeneous polymer solution of chloroform. The silyl sulfonate polysulfone is modified in the sulfonate form by reaction with sodium methoxide. The membranes were prepared by casting method. The prepared membranes were washed with water, dried and converted in protonic form for immersion in HCl solution before their characterization. Two samples of sulfonated polysulfone membrane (SPSf) were employed as electrolyte in the fabrication of solid-state supercapacitors. The former sample contained only the SPSf, whereas the second was in composite form being SPSf filled with 5% of SBA-15 silica. The electrodes for the supercapacitors was prepared with CMK-3 mesoporous carbon and Nafion ionomer. The latter had both the functions of binder and ion conductor. The structures of nanostructured silica template and carbon material was evaluated by transmission electron microscopy (TEM) small angle X-Ray diffraction (XRD) and BET analyses. The solid-state supercapacitors based on carbon electrodes and solid polymer electrolytes were characterized by cyclic voltammetry (CV), galvanostatic charge/discharge measurements and, electrochemical impedance spectroscopy (EIS) analyses. As a result, it was found that the supercapacitor with the composite SPSf membrane exhibited higher specific capacitance (105 F/g) compared to that with the membrane containing only SPSf (86 F/g). Further results on the structural features of synthesised nanostructured carbon, on the proton conductivity of the polymeric membranes and, on the effect of filler on supercapacitor performance will be shown during the presentation.