N‐Doping in Precursor Sol: Some Observations in Reference to In Situ‐Grown Carbon Film Electrodes for Supercapacitor Applications

Abstract

The effect of nitrogen doping in the precursor sol from different nitrogen‐bearing sources on the in situ‐grown carbon film is evaluated for use as an electrode in electrochemical capacitors. The film is developed by the electrospray coating of resorcinol–formaldehyde (RF) sol on carbon fiber paper, serving as the current collector of the capacitor and subsequent curing, solvent removal, and carbonization in situ. Ethylenediamine and melamine are the aliphatic and aromatic hydrocarbonaceous sources, respectively, that are added to RF in separate experiments. The interaction between the electrolyte ions and the electrode surface is enhanced due to the presence of nitrogen and oxygen functional groups, and is analyzed through energy‐dispersive X‐ray spectroscopy, elemental CHNS analysis, Fourier transform infrared spectroscopy, and X‐ray photoelectron spectroscopy analyses. At the same time, the difference between the cross‐linking mechanism in the two cases leads to different pore structures at the micro‐ and mesoscales in the carbonized product, as reflected in the scanning electron microscope images and nitrogen adsorption–desorption data. The electrochemical performances of the electrodes are analyzed with regard to the two sets of results, referred earlier, and the relative importance of the pore hierarchy induced by cross‐linking is discussed.

Revisiting the Effect of Pyrolysis Temperature and Type of Activation on the Performance of Carbon Electrodes in an Electrochemical Capacitor

“…In recent years, research on the development of carbon-based electrodes for ECs has focused on improving their surface area with a proper pore hierarchy and incorporating heteroatoms or functionalities into the carbon structure [ 2 , 3 , 4 , 5 , 6 ]. As most of the surface area for double-layer charge storage is held inside micropores (<2 nm pore size), the pore hierarchy or connectivity between meso-micropores plays a vital role in the rapid transport of electrolyte ions to the internal surface [ 7 ].…”

“…Such functionalities contribute to increase surface polarity, wettability, electric conductivity, and electron donor/acceptor properties, and also act as active sites for pseudocapacitance [ 2 ]. The incorporation of these functionalities into carbon through the precursor itself offers feasibility with a uniform distribution of functionalities over the carbon network and an improvement in bulk properties compared to other post-treatments used for functionalisation [ 6 ].…”

“…Carbons obtained from the sol-gel polymerisation of monomers, followed by solvent removal (drying step) and pyrolysis (also called carbonisation), are extremely popular as electrode materials for ECs, because of the tailorable pore size distributions, high surface area, and favourable surface chemistry [ 3 , 4 , 5 , 6 , 10 ]. Such properties are easily controlled through the cross-linked chemistry and the choice of operating parameters during processing steps.…”

“…Such properties are easily controlled through the cross-linked chemistry and the choice of operating parameters during processing steps. Sol-gel chemistry involves the addition and condensation reaction between hydroxylated benzenes (e.g., phenol, cresol, resorcinol, hydroquinone) and aldehydes (e.g., formaldehyde, furfural) to form a three-dimensional cross-linked polymeric gel network [ 6 , 10 ]. Particularly, carbon derived from the resorcinol-formaldehyde (RF) polymeric gel is widely studied as an electrode material due to its large surface area that stores charges through double layer formation, and the favourable pore hierarchy provides a rapid transport of ions.…”

Conjugated microporous polymer foams with excellent thermal insulation performance in a humid environment

“…Especially, CMPs, rstly reported by Cooper 21 with a large Pconjugated network, rigid structure, and physicochemical stability, have attracted much attention in water treatment, [22][23][24] supercapacitor 25,26 electrocatalysis, 27 and so on. Meanwhile, CMPs could generate a monolithic-foam with low density, superhydrophobic characteristics and certain compression resistance by own polymerization.…”