Preparation and coking property of binder pitch: effects of modification methods

Binder pitch was recognized as one of the important raw materials for the production of carbon/graphite electrode and anode of lithium-ion battery. The quality and application of carbon/graphite products was generally determined by the properties of the binder pitch. Thus, the high-quality binder pitch act a key role on the quality of carbon/graphite materials. In this work, the refined medium pitch was used as role material, the effects of modification methods on the properties of binder pitch (molecular structure, thermal-stability and the optical microstructure of pitch) and coking properties (optical microstructure of pitch coke, carbon microcrystalline structure and carbon surface morphology of pitch carbon, etc.) were detailed studied. The research results show that, the high-quality isotropic binder pitch (with softening point of 144 ℃, QI content of 0.46%, TI content of 26.74%, coking value of 51.53%, volatile matter of 56.65%) was obtained by two-step method, named oxidation polymerization- mild thermal polymerization method (first step: refined pitch was oxidized at temperature of 280 ℃ for 3 hours; second step: rapidly heated to the temperature of 360 ℃ and hold for 1 hour under N₂ atmosphere). The degree of aromatic condensation of the binder pitch was high and have fewer small molecule branched structures. The optical microstructure of the binder pitch coke obtained by thermal conversion and carbonization treatment had a leaflet and fibrous structure content of 83.92%. The disorder degree of the binder pitch coke was relatively low, and the microcrystalline structure was regular and orderly (the content of carbon microcrystals tends to be regular was as high as 90.89%, and the ideal graphite microcrystal content I_G/I_All was 18%).