Preparation Of ACM Based Activated Carbon Aerogels And Its Application In Electric Double-layer Capacitors

Due to the increasing depletion of fossil fuels and the deteriorating environmental problems, great attentions have been focused on the renewable energy resources. As an novel energy storage devices, electrical double-layer capacitors(EDLC) have achieved a huge development for decades. Among all the porous carbon materials, carbon aerogels is a kind of promising electrode material for EDLC. Recently,amphiphilic carbonaceous materials(ACM) based carbon aerogels have attracted considerable attentions due to their low cost, facile and environmental friendly, which meet the concept of green chemistry.In this paper, amphiphilic carbonaceous materials which prepared by the oxidation of coal tar pitch was selected as raw material. Through control the solvent that used in ACM dissolving process and solvent exchange process, organic aerogels(OAs) with different morphology were obtained. And various tools were used to study the structure and forming mechanism of OAs. ACM based activated carbon aerogels were prepared by KOH and ZnCl2 activation. The effect of activation conditions on the morphology, yield, surface area and pore structure of carbon aerogels was studied. Furthermore, the electrochemical performance of the prepared activated carbon aerogels was investigated.The results showed that PCAs prepared by KOH activation exhibits a large specific surface area. At the KOH/CAs mass ratio of 1.5, PCAs-1.5 sample exhibited surface area as high as 2598.2 m2/g and the mesopore size centered at 2~5 nm. Electrochemical characterizations demonstrated that PCAs samples showed superior capacitances and rate capacity as electrode material for EDLC in aqueous electrolytes(30% KOH). The specific capacitance of PCAs-1.5 reached 283 F/g at current density of 0.05 A/g, and still maintained 221.3 F/g as the current density increased to 40 A/g. Remarkably, PCAs-1.5 electrode showed stable cycle durability with only 5.73% capacitance fading after 5000 cycles at 1A/g. The activated carbon aerogels prepared by ZnCl2 completely maintained the original 3D network of CAs and possessed high yields(about 80%). Under the experimental conditions investigated, a activation temperature of 500? and impregnation ratio of 3:1 were found to be suitable for producing high-surface area porous carbons. The sample ACAs-500-3-2 which prepared under the optimized condition exhibited specific surface area as high as 1306.8 m2/g and pore size centered at 2~3 nm. As the electrode materials for EDLC(30% KOH), the specific capacitance of ACAs-500-3-2 reached 255.2 F/g at 0.05 mA/g and remained 82.4% of initiate capacitance as the current density up to 40 A/g, showing superior rate capacity.