Preparation of carbon aerogels and its application in electrochemical supercapacitors

The carbon aerogels are prepared by using resorcinol and formaldehyde as precursor, Na2CO3 as catalyst and water as solvent with sol-gel technology, following drying and carbonization at high temperature. The optimized parameters of the preparation of high specific surface area carbon aerogels in this paper have been investigated by adjusting the ratios of precursors and applying three activated processes: carbon dioxide physical activation process, potassium hydroxide wet chemical activation process, and two steps activation process of carbon dioxide and potassium hydroxide for the application of carbon aerogels in supercapacitors. Moreover the microstructure of carbon aerogels and their corresponding electrochemical properties have been characterized and analyzed. The results indicated that the original specific surface area and specific capacitance of the unactivated carbon aerogel are 820 m2/g and 151 F/g respectively as the molar ratio of resorcinol and sodium carbonate (R/C) is 1500. After the carbon dioxide physical activation process, potassium hydroxide wet chemical activation process, and two steps activation process respectively, their specific surface areas increased to 1589 m2/g, 1480 m2/g and 2119 m2/g and the specific capacitances of the samples reached to 181 F/g, 229 F/g and 259 F/g. By contrast, the two-step activation not only enhance the specific surface area, but also form a hierarchically porous structures of the carbon aerogels, which is advantageous to be applied in the supercapacitors.