Exploring New Routes in the Synthesis of Carbon Xerogels for Their Application in Electric Double-Layer Capacitors

Abstract

Resorcinol−formaldehyde carbon xerogels were prepared by means of two different synthesis methods: conventional (C) and microwave heating (MW). The influence of the heating method and the pH of the precursor solution on the textural and chemical properties of the carbon xerogels was investigated. It was found that by modifying the initial pH, it is possible to control the porosity of carbon xerogels independent of the heating method used. The electrochemical performance of a selection of synthesized carbon xerogels as electrode materials in electric double-layer capacitors was studied by cyclic voltammetry and charge/discharge experiments in an acidic medium (1 M H2SO4). The electrochemical performance of the carbon xerogels was compared to that of an activated carbon commercialized for this application (Norit Super DLC-50), and it can be seen that the carbon xerogels display similar specific capacitances to those of the commercial carbon. Moreover, carbon xerogels have a good cycle durability after 18 000 galvanostatic cycles, with a drop in specific capacitance of around 10%. This excellent cycle durability, together with the attractive properties of carbon xerogels and the saving of time and energy achieved with microwave-assisted synthesis, would make resorcinol−formaldehyde carbon xerogels promising materials for applications of an electric double-layer capacitor (EDLC).