Construction of S-doped hierarchical porous carbons by acid-free treatment strategy for supercapacitors

The pollution from acid treatment process in the preparation process of hierarchical porous carbons is a substantial challenge for industrial application of supercapacitors (SCs), which necessitates the development of green alternative technologies. In this work, S-doped hierarchical porous carbons (S-HPCs) are prepared from cheap coal tar pitch by a less harmful in situ KHCO3 activation strategy. The sample obtained at 800°C (S-HPC800) possesses 3D framework structure with hierarchical pores, large specific surface area (1485 m2 g-1) and O, S-containing functional groups. Due to these synergistic characteristics, SHPC800 as supercapacitor electrode exhibits high specific capacitance of 246 F g-1 at 0.1 A g-1 with a capacitance retention of 68.3% at 40 A g-1 and excellent cycle stability with 96.7% capacitance retention after 10, 000 charge-discharge cycles. This work provides an environmentally friendly approach to prepare advanced carbon-based electrode materials from industrial by-products for energy storage devices.