Nitrogen/sulfur co-doping assisted chemical activation for synthesis of hierarchical porous carbon as an efficient electrode material for supercapacitors

Nitrogen and Sulfur Codoped Porous Carbon Directly Derived from Potassium Citrate and Thiourea for High-Performance Supercapacitors

By introducing a heteroatom into carbon material, an effective improvement in capacitance can be realized owing to surface oxidation and reduction reactions of pseudocapacitors. Herein, a simple one-pot carbonization activation method was proposed to convert potassium citrate into three-dimensional interconnected porous carbon (PC). Then, an effective double heteroatom doping method by thiourea was used to prepare nitrogen-sulfur-doped PC (N,S-PC). This porous structure facilitates the storage of a large number of ions and reduces their diffusion path. The synthesized N,S-PC nanomaterial has a capacitance of 674 F/g at 1 A/g in a 1 M H₂SO₄ electrolyte, can retain 94.41% of the initial capacitance after 10 000 cycles at 5 A/g, and has a long cycle life. More importantly, a symmetric supercapacitor assembled with this material can exhibit an energy density of up to 32.6 (W·h)/kg at a high-power density of 750 W/kg. This is due to the high performance of N,S-PC in supercapacitor electrode materials.

Tailoring Hierarchically Porous Nitrogen-, Sulfur-Codoped Carbon for High-Performance Supercapacitors and Oxygen Reduction

Heteroatom-doped carbon materials are intensively studied in supercapacitors and fuel cells, because of their great potential for sustainably bearing on the energy crisis and environmental pollution. Although enormous efforts are put in material perfection with a hierarchically porous microstructure, the simultaneous optimization of both porous structures and surface functionalities is hard to achieve due to inevitable concurrent dopant leaching effect and structural collapse under required high pyrolysis temperature. In this study, an in situ dehalogenation polymerization and activation protocol is introduced to synthesize nitrogen- and sulfur-codoped carbon materials (NS-PCMs) with hierarchical pore distribution and abundant surface doping, which endows them with good conductivity, abundant accessible active sites, and efficient mass transport. As a result, the as-prepared carbon materials (NS-a-PCM-1000) show an excellent mass specific capacitance of 461.5 F g^-1 at a current density of 0.1 A g^-1 , long cycle life (>23 k, 10 A g^-1 ), and high device energy and power density (17.3 Wh kg^-1 , 250 W kg^-1 ). Significantly, NS-a-PCM-1000 also exhibits one of the highest oxygen reduction reaction activities (onset potential of 1.0 V vs reversible hydrogen electrode) in alkaline media among all reported metal-free catalysts.

Dictyophora-derived N-doped porous carbon microspheres for high-performance supercapacitors

PCMS-T hierarchical porous structures were prepared from biomass dictyophora as electrodes for high-performance supercapacitors.

N/S co-doped coal-based porous carbon spheres as electrode materials for high performance supercapacitors

N/S co-doped porous carbon spheres were prepared using one step strategy for high performance supercapacitors.