关键词: 自掺杂氮, 多孔交联碳纳米片, 对称超级电容器, 生物质

Self N-doped porous cross-linked carbon nanosheets (N-ICNs) are prepared by one-step activation carbonization using dandelion seeds. The dandelion seeds are rich in nitrogen without any additional doping treatment, which can be served as an ideal carbon precursor. The microstructure and composition of the prepared carbon materials are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). It can be seen from the SEM and TEM spectra that the N-ICNs exhibit the porous interconnected structure, which can facilitate the transfer of the electrons and the dispersion of the electrolyte ions. Moreover, the XRD spectra show the defects in the amorphous carbon material. Nitrogen adsorption/desorption isotherms of the N-ICNs show a high specific surface area of 1564 m²·g^-1, and the pore size distribution shows numerous micropores and macropores, which contributes to the formation of double layer capacitance and the accessibility of the electrolyte ions. The wide-scan spectra present the presence of C, N and O atoms. Interestingly, the N content of the N-ICNs without any extra doping treatment is high (2.88%). Based on the high nitrogen content, the N-ICNs exhibit a good specific capacitance of 337 F·g^-1 at a current density of 1 A·g^-1 with an excellent capacitance retention of 99% after 10000 cycles. The good electrochemical performances mainly caused by the nitrogen functional groups in the carbon lattice, which can improve the wettability as well as provide pseudocapacitance due to the redox reactions of amine groups. In addition, the symmetric supercapacitor assembled with N-ICNs in the operating voltage range of 0~2 V shows high energy density of 25.3 Wh·kg^-1 at the power density of 900 W·kg^-1, which are superior than the other carbon materials reported. And the capacitance retention can retain 98% after 10000 cycles. Therefore, the low-cost biomass-derived porous interconnected carbon material can be a promising electrode material for supercapacitors.

Key words: self N-doping, porous interconnected carbon nanosheets, symmetric supercapacitor, biomass