Study On The Multi-scale Structures And Application Of Carbonaceous Precursor Pitch

As the byproduct of chemical industry, pitches have an extensively sources, and theresearches on improving the industrial added value of pitch have been carried outincreasingly. However, the changes in performance are based on the structuraltransformation of samples. In this work, proceeding from the multi-scale structures ofpitches, the structural features of quinoline insolubles(QI) in high softening pointpitches and the microstructure of high softening point pitches as well as the structuralinfluences of phenolic resin on mesocarbon microbeads(MCMB) have beeninvestigated. Meanwhile, the activated MCMB modified by phenolic resin wereinvestigated by electric double-layer capacitor (EDLC).For QIs’ structural characterization, four kinds of high softening point pitches withsimilar softening point but different optical texture were selected as the raw materials.Results showed that the QIs in anisotropic mesophase pitches were larger than that inisotropic pitch, with a higher H/C value. It was also proved that the micro-carbonlayer arranged more ordered in QIs that extracted from anisotropic mesophase pitch.The present work attempted to use the microtomy as sample preparation method fortransmission electron microscope (TEM) for the first time, by which to examine themicrostructure of mesophase pitch. Dozens of nanometers thick slices were received,and it can be seen under the TEM that nanometer-layer are regularly piled up, with noobvious structural defects, randomly distributed in the micelle structure of mesophasepitch.The thermoset (Resol) and thermoplastic (Novolac) phenolic resin were chosen asadditives, and the morphology and microstructure of MCMB prepared by thermalpolymerization were investigated. Then the MCMB were activated by KOH using thedirect activation method and the first carbonization and then activation method, theirelectrical performance were examined by EDLC. It turns out that the addition of resinhas little impact on sphere shape but the pore structure and carbon microcrystal. Thespecific surface area, pore volume and the rate of mesopore were improved greatly byadding phenolic resin, especially by the resol type, the specific surface area ofactivated MCMB can reach2732m~2/g with the weight proportion of KOH to carbon was3. Meanwhile, the sample had an excellent EDLC performance, betterreversibility in different scan rate, maximum discharge specific capacitance (350F/gin current density at50mA/g) and small internal resistance. Results indicated that thecrosslink structure in Resol was more conducive to the pores, and the disruptedcarbon layer made the immerging of electrolyte easier. In addition, the directactivation method was better than first carbonization and then activation method,whether on the pore structure or the electrochemical properties.