N, S co-doped porous carbon with high capacitive performance derived from heteroatom doped phenolic resin

Abstract

Introducing fast pseudo-capacitance is an effective strategy to improve the capacitive performances of carbon-based materials. Here, thiourea is used as nitrogen and sulfur source to dope resorcinol formaldehyde polymer. Besides the forming of copolymer of thiourea and resorcinol formaldehyde resin, the thiourea resin also acts as template to adjust the hierarchical microstructure. The N, S co-doped porous carbon exhibits specific surface area of 3599.0 m2 g−1 and wide pore distribution. The specific capacitance of the optimized sample can reach 461.7 F g−1 in 6.0 mol L−1 KOH electrolyte at current density of 0.1 A g−1, and still retains 337.5 F g−1 at current density of 10.0 A g−1, indicting good rate capability. The assembled symmetric device exhibits the maximum energy density of 14.9 Wh kg−1 at the power density of 61.9 W kg−1 based on the active materials. The capacitance can retain 98.3 % of the initial capacitance after 10,000 cycles at current of 10.0 A g−1. Using organic electrolyte, the operating voltage can be extended to 2.1 V, so the energy density of the device reaches 38.3 Wh kg−1 at 262.5 W kg−1. This co-doped strategy provides an effective approach to prepared carbon-based materials with high capacitive performance.