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

Abstract

N,O-containing micropore heteroatom carbon frameworks (MHCFs@600) were synthesized by ionothermal synthesis approach using 4,4′-(4-oxophthalazine-1,3(4H)diyl)dibenzonitrile. (CH 3 CH 2 CH 2 CH 2 ) 4 N + (PF 6 ) − 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 (f-MHCFs@600) rich in N (6.15 wt %), O (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). f-MHCFs@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 Ω decreased from 1.68 to 0.318 Ω and R ct changed from 25 to 4.2 Ω in the high-frequency area of the

A Novel Strategy of In Situ Trimerization of Cyano Groups Between the Ti3C2Tx (MXene) Interlayers for High-Energy and High-Power Sodium-Ion Capacitors

“…Therefore, engineering high pseudocapacitive heteroatoms (such as N, P, and S) on the surfaces and between the interlayers of Ti 3 C 2 T x seems to be a good strategy [ 17 , 18 ]. In particular, N has the excellent characteristics of electronegativity and pseudocapacitance [ 3 , 19 ], which could significantly improve the surface electronic and chemical properties of Ti 3 C 2 T x electrodes. However, the synthetic strategy based on chemically doped MXenes has not been clearly established.…”

“…Na-dca as the N-source has low toxicity and light pungent smell compared to urea and melamine [ 20 ]. More importantly, the sp 2 -hybridized triazine rings provide high as well as stable N atoms, which are connected by the strong covalent bonds for ensuring the stability during electrochemical cycles [ 19 ]. Thus, we proposed a reliable and controllable strategy for achieving highly N-doped Ti 3 C 2 T x through a highly novel method of the in situ trimerization of cyano groups (C≡N).…”