| Carbon aerogel,a new type of carbon material,has advantages of high surface area,nanoscale continuous porous,low density,good electrical conductivity and stable physicochemical properties,which is an ideal electrode material for the preparation of capacitors with high energy density and high power density.The preparation process of carbon aerogel required higher temperature and longer time according to the reports and supercritical drying technology was usually used,which caused high risks,high cost and difficulty for the preparation of carbon aerogel and the application and extension were limited.In this paper,carbon aerogel were synthesized with resorcinol,formaldehyde and phloroglucinol as raw materials,which can reduce the reaction temperature and shorten the reaction time.Supercritical drying technology was instead by atmospheric pressure drying technology in order to simplify process and reduce cost of carbon aerogel preparation.The surfactant P123,element Ni and Fe were added to improve the structure,conductivity,capacitive property and stability.Three parts are included in this thesis:1.The cardon aerogel was synthesized using sol-gel polymerization,solvent exchange,Atmospheric pressure drying technology and high temperature carbonization with phloroglucinol,resorcinol,formaldehyde as raw materials and sodium carbonate as catalyst.The influence factors on sol-gel reaction were investigated and the experimental conditions for the synthesis of organic aerogel were optimized and as follows:molar ratio of phloroglucinol to resorcinol was 1:4,molar ratio of phloroglucinol-resorcinol to catalyst was 800,raw material concentration was 35%.The carbon aerogels with average specific surface area of 609.11 m2 g-1 and the average pore size of 5.42 nm were obtained under the optimum conditions.The average specific capacitance of cardon aerogel was 114.6 F g-1 in 6 mol-L-1 KOH electrolyte and cyclic voltammetry curves tended to ideal rectangle.The experimental results showed that the prepared carbon aerogel had good capacitive property and reversibility.2.The carbon aerogel was synthesized by adding surfactant P123 in raw materials.the adsorption curve was IV and the hysteresis loop was HI when mass ratio of P123 to phloroglucinol-resorcinol was 1:2.The results showed that Carbon aerogel is mainly composed of mesoporous and pore size of carbon aerogel is about 10 nm.The better Electric double layer capacitors and cyclic stability were observed in 6 mol L-1 KOH electrolyte when carbon aerogel was used as electrode materials with the potential range from-0.8～0 V.The specific capacitance was 131.2 F·g-1 with a current density of 0.5 A·g-1.The surface tensions of the water and acetone were reduced and the specific surface area and structure of carbon aerogel were improved by the adding P123.3.Ni-doped Carbon aerogel and Fe-doped Carbon aerogel were successfully prepared by precursor doping method.The structure and electrical conductivity of carbon aerogel were optimized and electrochemical performance was improve with the changing of the content of nickel and iron.In 6 mol·L-1 KOH electrolyte,the electrochemical performances of Ni-doped carbon aerogel and Fe-doped carbon aerogel electrode materials were improved,which had better capacitive behavior and electrochemical reversibility with potential range of-0.8～0V.The specific capacitance was 134.4 F·g-1 at a current density of 0.5 A·g-1 with the mass fraction of nickel of 0.5%and specific capacitance was 125 F g-1 when the mass ratio of phloroglucinol-resorcinol to iron was 1:2.The result showed that conductivity,specific surface area and pore size distribution of carbon aerogel were improved by nickel and iron doping. |
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