Preparation Of Carbon Aerogels By Ambient Pressure Drying And The Supercapacitive Performance

Potassium acetate (sodium acetate) was used as a new catalyst in the polycondensation of resorcinol with formaldehyde and carbon aerogels for supercapacitor were prepared by ambient pressure drying instead of supercritical drying. The morphology and electrochemical properties of the samples were characterized by field emission scanning electron microscopy, cyclic voltammetry and chronopotentiometry. The effects of catalyst concentration and pyrolysis temperature on the capacitive performance were studied. Sodium acetate (magnesium acetate) resulted in not only the formation of interconnected nanoparticles, through-continuous pore network but also the enhancement of electrochemical capacitance. The specific capacitance of the carbon aerogel was as high as 296 F g^-1.Carbon aerogels were prepared via a sol-gel process from the polycondensation of resorcinol with formaldehyde by ambient pressure drying and pyrolysis at 1073K. Peroxide was used as a new additive in the polycondensation process. Samples were characterized by field emission scanning electron microscopy, nitrogen adsorption, cyclic voltammetry and chronopotentiometry. The effects of peroxide on the morphology pore structure and electrochemical properties were studied. The preparation of carbon aerogels could be realized by ambient pressure drying instead of supercritical drying with the addition of peroxide at high catalyst concentration. Peroxide also played a key role in preventing the shrinkage of the aerogels, forming interconnected microspheres, increasing the specific surface area and improving electrochemical performance. The specific capacitance of carbon aerogel was improved from 85 F/g to 256 F/g by using peroxide as the additive.Carbon aerogels for supercapacitor were prepared by ambient pressure drying instead of supercritical drying as the wet gels were frozen before drying. Three different kinds of catalysts were selected, which were sodium carbonate, sulfuric acid and carbamide. The R/C and the R/W ratio were varied in order to optimize the derived carbon aerogels with regard to capacity. The electrochemical properties of the samples were characterized by cyclic voltammetry, electrochemical impedance Spectroscopy and chronopotentiometry. The results indicated that the as-prepared carbon aerogels prepared high specific capacitance and low resistance.Pb-doped and Zn-doped carbon aerogels for supercapacitor were prepared by ambient pressure drying, respectively. The concentration of the metal was varied in order to optimize the derived carbon aerogels with regard to capacity. The morphology and electrochemical properties of the samples were characterized by field emission scanning electron microscopy, cyclic voltatnmetry and electrochemical impedance Spectroscopy. The results indicated that the Pb-doped carbon aerogels possessed higher specific capacitance and lower resistance. In addition, Nu₂O₃/CRF and Ta₂O₅/CRF composite electrodes were prepared, respectively. The electrochemical properties of the samples were characterized by cyclic voltammetry and electrochemical impedance Spectroscopy. The results indicated that Ta₂O₅/CRF composite electrodes possessed higher specific capacitance and lower resistance.