Effect of iodine treatment on structural and electrochemical performance of coal tar pitch based carbon materials for sodium ion batteries

Coal tar pitch (CTP) is a precursor of soft carbon materials with great potential for sodium-ion batteries (SIBs) due to the simple structural regulation. Exploring the interrelationships between the structure and performance of high-performance anode materials is a challenging. In this paper, a series of carbon materials for the anode of SIBs are prepared by controlling the ratio of iodine to CTP. Under the action of iodine, CTP transforms from soft carbon to hard carbon precursor followed by carbonization to obtain the pitch-based carbon materials. The relationship between the structure and electrochemical performance of the as-prepared carbon material is discussed. The results demonstrate that the material has more defects and larger interlayer spacing. At lower current density, a specific capacity of 262.6 mAh g−1 146% higher than pure pitch (179.5 mAh g−1) is obtained. Meanwhile, 82.64% of its original capacity is kept after 500 cycles at 1 A/g. This simple and effective method has implications for further exploring the influence of structural modifications in carbon materials on the electrochemical performance and sodium storage mechanism.