Structure evolutions and high electrochemical performances of carbon aerogels prepared from the pyrolysis of phenolic resin gels containing ZnCl2

Abstract

Carbon aerogels (CAs) were prepared via the pyrolysis of phenolic resin gels (PRGs) containing ZnCl2. The pyrolysis of PRGs and the activation of resulted amorphous carbons in CAs can be carried out in one step. Structure characterizations of CAs were performed by X-ray diffraction, Raman spectrum and gas adsorption-desorption method. Electrochemical performances of CAs were investigated by cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy. CAs with specific surface area of 2846m2g−1 can display its specific capacitance of 246Fg−1 at 1Ag−1 and 219Fg−1 at 10Ag−1. The addition of ZnCl2 in matrix of PRGs by a hydrothermal treatment can effectively avoid its serious volatilization at higher temperatures and enhance its activation efficiency. A series of structure evolutions in CAs including their specific surface areas, pore volumes and accumulation states of laminar carbon molecules can be caused by changing the content of ZnCl2 in PRGs. High electrochemical performances of CAs are resulted from their adjusted carbon structures. The relation between the structure evolutions in CAs and their improved electrochemical performances is also discussed.