China Nonferrous Metallurgy

Coal tar pitch （CTP）， a product derived from coal tar processing， is rich in polycyclic aromatic hydrocarbons （PAHs）， and is an ideal precursor for the preparation of hard carbon anode materials for sodium-ion batteries （SIBs） because of its high carbon yield， tunable porosity， low cost， and easy processability. However， during high-temperature carbonization， the polycyclic aromatic structure of CTP is prone to forming dense graphitic microcrystals， which hinder the insertion/extraction of sodium ions and limit its application in SIBs. To address this issue， this paper proposes a “gas-solid dual-interference” strategy， in which the gas-phase and solid-phase products generated during the decomposition of sodium perchlorate （NaClO₄ ） synergistically regulate the structure of the coal tar pitch precursor：① the gas-phase decomposition product （O₂ ） promotes the cross-linking of coal tar pitch molecules and effectively suppresses the graphitization process；② the solid-phase decomposition product （NaCl） hinders the strong π-π interactions between the aromatic chains of the pitch and alleviates excessive stacking while optimizing the pore structure. The optimally prepared CTP-based hard carbon （P₂₀-500^-1400） exhibits a capsule-like nano-graphitic structure and is rich in abundant pore structures， which provide abundant active sites for sodium-ion storage， as well as facilitated pathways for sodium-ion transport. Compared with the unmodified sample， the reversible capacity of P₂₀-500^-1400 is increased by 1. 8 times to 232. 5 mAh·g^-1 ， with an initial coulombic efficiency of 84%. The capacity is 187. 4 mAh·g^-1 at a high current density of 1. 5 A·g^-1 ， and can still be maintained at 190. 5 mAh·g^-1 after 1 000 cycles at 0. 3 A·g^-1 ， with a capacity retention of 91%. This work provides a theoretical basis and technical reference for the development of high-performance and low-cost anode materials for SIBs.