Preparation And Characterization Of Carbon Aerogels

In this paper, using ambient pressure drying, carbon aerogel is made of resorcinol and formaldehyde. Characterized by SEM, XRD, FTIR and nitrogen adsorption test, the microstructure and formation mechanism of carbon aerogels is researched and analyzed. Using laser heat-conduction tester, the thermal conductivity of carbon aerogels is tested, and the influence of temperature on thermal conductivity is analyzed. The electrochemical performance of carbon aerogels electrode is tested with the method of cyclic voltammetry test.Research found that total concentration of reactant and catalyst can strongly influent drying of the organic gel in the process of drying shrinkage in atmospheric conditions. When reactants total concentration is 40% and catalyst concentration R/C is 500, drying shrinkage is low to the radial 4.83%. With the increasing of catalyst's concentration, the surface of carbon aerogels (SBET) and the hole volume (Vmeso) increase first and then decrease. When the ratio of R/C is 500, carbon aerogels SBET is 976m2·g^-1, and Vmeso is 1.7094 cm3·g^-1.Carbon aerogel, which is made by resorcinol-formaldehyde, is similar to the structure of graphite, and also belongs to the porous carbon material which is difficult to graphitizate. As temperatures'rising, microcrystalline length La increases. Microcrystalline length La increases to 1.86nm when the temperature is 900℃, and to 2.86nm when 1800℃. With temperature rise, the pore structure parameters of carbon aerogel change greatly; specific area and hole volume decrease; pore size increase. Under the condition of normal temperature, carbon aerogel's thermal conductivity is 0.09W m^-1 K^-1 at 0.44 g cm^-3. With the rising of temperature, the thermal conductivity increases. When the temperature goes up to 1000℃, the thermal conductivity is 0.56 W m^-1 K^-1.The cyclic voltammetry test is carried out in this paper. And results have been found that these electrodes which are made of carbon aerogels materials have characteristic of electric double layer charge-discharge. After 30 times cycle, material still has good stability, the capacitance of electrode can sustain in higher value. Concentration of catalyst influence its electrochemical properties through controling the pore structure of carbon aerogels, and the specific capacitance is relatively higher and equal to 124.97 F·g^-1 when R/C is 1000. The specific capacitance of carbon aerogels made of SiO₂ can reach 133.21 F·g^-1.