Simple Fabrication of High-Efficiency N,O,F,P-Containing Electrodes through Host-Guest Doping for High-Performance Supercapacitors

N,O-containing micropore heteroatom carbon frameworks (MHCFs@600) were synthesized by ionothermal synthesis approach using 4,4'-(4-oxophthalazine-1,3(4H)diy)dibenzonitrile. (CH3CH2CH2CH2)(4)N+(PF6)(-) was then introduced into the hierarchical pore structure with pore size ranging from 0.3 to 5.8 nm by simple and high-efficiency host-guest interaction to obtain an electrode material (fMHCFs@600) rich in N (6.15 wt %), 0 (8.22 wt %), P (1.61 wt %), and F (5.86 wt %). After introduction of F and P, the prepared f-MHCFs@600 showed a voltage window (1.4 V) larger than the theoretical potential of water (1.23 V). fMHCFs@600 exhibited a high specific capacitance of 244.8 F g(-1) at 0.1 A g(-1) and an excellent cycling stability (capacitance retention of 98.5% over 10 000 cycles) in a three-electrode system at a high voltage window (1.4 V) because of the stable existence of P and F. In particular, compared to the MHCFs@600, R Omega decreased from 1.68 to 0.318 Omega and R-ct changed from 25 to 4.2 Omega in the high-frequency area of the f-MHCFs@600. Moreover, the introduction of phosphorus and fluorine increased the voltage window, resulting in energy density from 3.78 to 8.1 W h kg(-1) at 1 A g(-1) and the maximum power density of 3500 W kg(-1) at 10 A g(-1) with 1 M H2SO4 as the electrolyte in Swagelok cells. Therefore, the proposed method was a practical and excellent strategy for synthesizing heteroatom-rich carbon materials and significantly increased energy density for energystorage/conversion applications.