Super microporous sulfur-doped hard carbon synthesized from a π-stacked Polybenzo[c]thiophene boosting reversible lithium-ion insertion at room temperature

Abstract

Synthesis of porous carbon materials with controlled textural properties is an all-time challenging process for energy storage applications. Aromatic polymers possess high rigidity due to their π-π stacking arrangement and could serve as robust precursors to produce porous carbon. Herein, super-microporous sulfur-doped hard carbons (SM-SDHCs) were synthesized from a highly ordered aromatic polybenzo[c]thiophene between 600 and 800 °C by using KOH as an activation agent. The degree of carbonization and defects were enhanced as the temperature increased from 600 to 800 °C as confirmed by X-ray diffraction and Raman spectroscopy techniques. All the SM-SDHCs exhibit a super-microporosity (<2 nm) and high surface area (1126–1444 m2 g−1). Among the three synthesized carbons, the SM-SDHC800 exhibited a high discharge capacity of 760.7 mAh g−1 at 20 mA g−1 and showed excellent cycle stability at 200 mA g−1 for 250 cycles. The reversible lithium-ion insertion of SM-SDHC800 anode is accredited to its high degree of carbonization, defect-rich quality, high interlayer distance, and microporous texture with large pore volume (0.68 cm3 g−1). In addition, the excellent cycle stability at 2 A g−1 for 1000 cycles shows its robustness for high C-rate LIBs. Polybenzo[c]thiophene precursor is a perceptive choice to produce sulfur-doped super-microporous hard carbon with controlled textural properties and could bring dramatic advances in the synthesis of nanostructured carbon materials for energy storage applications.