A new strategy for preparation of high-performance onion-like anode material from coal tar pitch residue

The quinoline insoluble substances (QI) were separated from coal tar pitch (CTP) residue using solvent extraction sedimentation method. The formation mechanism, microstructural characteristics, and electrochemical performances of QI were systematically evaluated. The generation of QI sample was thought to be induced by the interactional force of large lamellar pyrolytic aromatic hydrocarbon fragments in CTP. Since, the as-prepared QIs with spherical particles possessing a wide size distribution were beneficial to improve the tap density of anode, it was proposed to prepare anode material for lithium-ion battery in a large-scale. The microstructure of QI particles was varied from the surface to the inner section. Particularly, the cyclic annular graphitic layers were clearly observed indicating the formation of onion-like texture. After carbonization at 700 °C and 900 °C, vast of bent and faceted planes and/or polycyclic aromatic hydrocarbon clusters could be gradually transformed into closed cyclic structures; thus, the outer graphitic layers were locally distorted. Furthermore, the QIs after activation could fabricate amorphous carbon coated granules. Such defective structures greatly increased QI’s specific surface area to be 2538 m2/g. And the amorphous carbon coated graphitic layer structures favored of the electrolyte penetration, thus, providing more appropriate sites for ions storage. Eventually, the electrochemical performance of activated QIs was significantly improved to achieve a reversible capacity of 1011.4 mAh/g after 100 cycles of charge-discharge at a current density of 100 mA/g.