Carbon Aerogels as Electrode Material in Supercapacitors

Due to their large specific surface area and their high electrical conductivity carbon aerogels are promising materials for electrodes in electrochemical double-layer capacitors ("supercapacitor"). The carbon aerogels were made via pyrolysis of resorcinol formaldehyde aerogels. The latter were prepared by supercritical and subcritical drying as well. The important findings of our investigation were, that the highest capacities of 46 F/cm(3) were measured for samples with a density of about 800 kg/m(3) pyrolyzed at 800 degrees C. Also it was shown that RF-gels with molar resorcinol/catalyst ratios >= 1000 or higher can be dried subcritically without cracking or significant shrinkage. Carbon aerogels derived from these RF-aerogels have a small mesopore surface area, however an especially large micropore area. They provide electrical capacities which are most suitable for their use in supercapacitors.