Preparation Of Mesocarbon Microbeads And Applications

Mesocarbon microbeads(MCMB) is a new type carbon material invented in 1970's. For its special parallel molecule arrangement and micro-spherical appearance, it has been regarded as a promising material for electrode material of lithium ion rechargeable battery, high-density carbon, super active carbon and packing materials. Besides pyrolysis of pitch-like materials from which MCMB was firstly separated and so called, MCMB can also be produced by some other methods such as emulsion and suspension. However, the MCMB made by emulsion and suspension has the characteristics of fusible or resolvable, and needs to be stabilized before carbonization. Additionally it is difficult to get rid of some non-carbon elemental impurities such as silicon and iron absorbed during the sphericalization procedure. The problems for pyrolysis are low yield, difficult separation, wide diameter distribution and so on. However, the raw material is easy to get, and the MCMB can be infusible and irresolvable. The thesis was aimed at finding some ways to solve these problems.Two key steps for pyrolysis are involved: heat treatment of a raw material to produce spherically shaped mesophase and separation of the mesophase spherules from matrix. The raw material must own moderate reactivity and viscosity, well planar molecules, among which, the viscosity can be said to be a dilemma. Low viscosity makes separation easier but on the other hand results in coalescence.The mesophase-transforming behaviors are observed of the selected materials: a crude coal tar CT0, a refined coal tar CT1 and a naphthalene pitch NP. The following conclusions can be drawn:(1) Mesophase spheres is easily formed in NP, however, their sizes are uneven and the spheres are difficult to separate from matrix.(2) The mesophase spheres generated in CT1 are even as well as of good texture, then, the separation is difficult too.(3) The crude coal tar CT0, comparatively, is difficult to convert into mesophase, and the produced mesophase spheres after a long-time reaction...