High performance sulphur-doped pitch-based carbon materials as anode materials for sodium-ion batteries

Sulfur-doped pitch-based carbon materials with a high sulfur content were prepared by a two-step heat treatment method using medium-temperature coal tar pitch as the carbon source and sublimated sulfur as the sulfur source. The effect of the final carbonization temperature on the composition, microstructure and electrochemical properties of the materials suitability as anode materials for sodium ion batteries were investigated. Results show that by increasing the final carbonization temperature the sulfur content of the materials decreases significantly, and the specific surface area and interlayer spacing gradually increase. Among the carbons obtained at different final carbonization temperatures, the sulfur content of the carbon at 800 oC was 20.19 wt.% and its interlayer spacing 0.368 nm, and its reversible capacity was 482.8 mAh/g at 0.1 A/g for the first cycle and had values of 245.9 and 103.7 mAh/g at 0.5 and 5 A/g, respectively after 500 cycles. The excellent sodium storage performance of the carbon at 800 oC is attributed to its high sulfur content, large interlayer spacing and suitable pore structure.