Highly tri-heteroatom doped porous carbon for aqueous and flexible quasi-solid-state zinc-ion hybrid supercapacitors

Abstract

Porous carbon, a promising low-cost cathode material for zinc-ion hybrid supercapacitors (ZHSCs), is plagued by inferior hydrophilicity and insufficient active sites during charge/discharge process. Herein, a highly tri-heteroatom co-doped porous carbon material (HSAC_NS0.5) was prepared from the pyrolysis of Humulus scandens combining heteroatom doping. The high oxygen, nitrogen and sulfur content (total about 29.2 %) combining superior specific surface area (1505.9 m² g⁻¹) and hierarchical porous structure leads to superior wettability and abundant active sites, resulting in rapid kinetic behaviors and considerable ions adsorption capacity. Furthermore, the high content of heteroatoms provides extra pseudocapacitance. Consequently, the aqueous ZHSC based on HSAC_NS0.5 displays an excellent specific capacitance of 414.4 F g⁻¹ at 0.5 A g⁻¹, and energy density of 187.4 Wh kg⁻¹ at a power density of 810 W kg⁻¹. Moreover, the HSAC_NS0.5 cathode based flexible quasi-solid-state ZHSC operates well at different bending states. Even at a high mass loading of 17.3 mg cm⁻², the ZHSC shows cycling stability and a superior areal capacitance of 4.27 F cm⁻².