Sulfur-doped porous carbon nanosheets as an advanced electrode material for supercapacitors

Abstract

Direct carbonization and simultaneous chemical activation of a cobalt ion-impregnated sulfonic acid ion exchange resin is found to be an efficient approach to the large-scale synthesis of sulfur-doped porous carbon nanosheets (S-PCNS) for supercapacitors with high specific energy and excellent rate capability. The as-prepared S-PCNS showed a three-dimensional interconnected structure, high graphitization degree, high C/O atomic ratio (22.9 : 1), high-level sulfur doping (9.6 wt%), high specific surface area (2005 m² g⁻¹), and good porosity. The S-PCNS serving as an electrode material for supercapacitors exhibited a specific capacitance as high as 312 F g⁻¹ at 0.5 A g⁻¹, excellent rate capability (78% of capacitance retention at 50 A g⁻¹), high energy density (11.0 W h kg⁻¹ at 0.5 A g⁻¹), and outstanding cycling stability (∼97% of its initial capacitance after 10 000 cycles at 2 A g⁻¹) in 6.0 M aqueous KOH electrolyte. Due to the unique structure of S-PCNS, the specific capacitance of S-PCNS is higher than that of sulfur-doped activated carbon. The excellent capacitance performance coupled with the facile synthesis of S-PCNS indicates a potential electrode material for supercapacitors.