Facile and green synthesis of 3D honeycomb-like N/S-codoped hierarchically porous carbon materials from bio-protic salt for flexible, temperature-resistant supercapacitors

Abstract

3D honeycomb-like N/S-codoped hierarchically porous carbon materials were prepared from chitosan-protic salt ([Chit][HSO4]) by a combined method of double soft-template and solvent-free self-assembly. The key to this preparation strategy: no any solvents or catalysts are used; F127 and sodium dodecyl sulfate are respectively used as mesoporous and macroporous soft templates, as well as [Chit][HSO4] not only can be used as a carbon source, N/S source, but also as a microporous porogen during carbonization. The features of unique honeycomb-like hierarchical pore structure, large specific surface area of 927 m2 g−1 and high heteroatom doping (N: 5.13 at. %, S: 2.51 at. %) simultaneously exist, significantly improving the electrochemical performance of as-obtained carbon materials. A high capacitance of 302 F g−1 and an excellent cycling stability with 99% capacity retention over 5000 cycles have been obtained in KOH electrolyte. Notably, the assembled symmetric flexible solid-state supercapacitors still maintain excellent capacitance property and stability under the extreme temperatures (−20 °C ∼ 100 °C) and bending (0° ∼ 180°). Furthermore, in Na2SO4 electrolyte, the supercapacitors display an outstanding energy density of 17.6 Wh kg−1 at a power density of 250 W kg−1. The fascinating performance significantly endows 3D honeycomb-like N/S-codoped hierarchically porous carbon materials with great potential for high-efficient energy storage.