In situ formation/carbonization of quinone-amine polymers towards hierarchical porous carbon foam with high faradaic activity for energy storage

Heteroatom doping is a very important approach to improve the performances of carbon-based electrode materials applied in the energy storage and conversion field. Herein, a strategy based on the design of faradaic redox active sites has been developed to synthesize nitrogen and oxygen co-doped carbon foam with a hierarchical porous structure. By a facile two-step method of incipient impregnation and carbonization, the quinone-amine polymer (PAQ) precursor can be in situ polymerized and carbonized on the surface of a nanosized MgO template to obtain carbon foam after removal of MgO with acetic acid. The obtained carbon foam possesses a high content of heteroatoms (total 12.26 at%) as well as faradaic active sites including nitrogen-and oxygen-containing functional groups, which not only enhance the wettability of the electrode material surface to electrolyte but also impart high pseudo-capacitance to the carbon-based skeleton. In addition, the hierarchical micro-meso-macro porous structure provides a large specific surface area (1215 m(2) g(-1)) and a mediated pathway for electrolyte ion diffusion. Serving as a symmetric supercapacitor electrode material in aqueous electrolyte, the co-doped carbon foam yields excellent performance, delivering a high specific capacitance of 321 F g(-1) at 1 A g(-1), a superior energy density of 15.91 W h kg(-1) at a power density of 0.4 kW kg(-1), and excellent long-term stability, retaining 98% of its initial capacitance after 15 000 cycles at 5 A g(-1).