Deflated balloon-like nitrogen-rich sulfur-containing hierarchical porous carbons for high-rate supercapacitors

Nitrogen-rich sulfur-containing hollow carbon spheres with open macroporous structure and wrinkled surface were fabricated through co-assemble of melamine resin and silica nanospheres by using methionine as catalyst and sulfur source. The obtained materials possessed high nitrogen content (14.16–16.59%) and controllable sulfur doping level (0.06–0.23%). Benefited from the enriched doped heteroatoms and hierarchical porous structure containing micropores, mesopores and macropores, the obtained carbons show high specific capacitance (230 F g⁻¹ at 0.5 A g⁻¹) and excellent rate performance (80% capacitance retention at 10 A g⁻¹). In addition, the carbons investigated by two-electrode system with polyvinyl alcohol/KOH gel electrolyte showed a high capacitance of 208 F g⁻¹ and good long-term stability (94% over 5000 cycles).