Nitrogen‐Enriched Nonporous Carbon Electrodes with Extraordinary Supercapacitance

Abstract

Nitrogen‐enriched nonporous carbon materials derived from melamine–mica composites are subjected to ammonia treatment to further increase the nitrogen content. For samples preoxidized prior to the ammonia treatment, the nitrogen content is doubled and is mainly incorporated in pyrrol‐like groups. The materials are tested as electrodes for supercapacitors, and in acidic or basic electrolytes, the gravimetric capacitance of treated samples is three times higher than that of untreated samples. This represents a tenfold increase of the capacitance per surface area (3300 µF cm−2) in basic electrolyte. Due to the small volume of the carbon materials, high volumetric capacitances are achieved in various electrolytic systems: 280 F cm−3 in KOH, 152 F cm−3 in H2SO4, and 92 F cm−3 in tetraethylammonium tetrafluoroborate/propylene carbonate.

Nitrogen doped superporous carbon prepared by a mild method. Enhancement of supercapacitor performance

“…Likewise, the presence of nitrogen on the surface of activated carbons improves the performance of activated carbon as electrodes of supercapacitors by increasing the wettability of the surface, the electrochemical stability, the conductivity or the contribution of pseudocapacitive processes [5][6][7][8]. Inversely to the ubiquity of surface oxygen groups, nitrogen functionalities are not as easily introduced in the structure of carbon materials, and the development of new procedures for obtaining nitrogencontaining porous carbons has therefore attracted a great interest.…”

Charge carrier exchange at chemically modified graphene edges: a density functional theory study

“…18,20 For instance, recent work has shown increased charge transfer in nitrified active carbon. 21 The mechanism is believed to be related to the incorporation of nitrogen ions near the ribbon edge and proton transport between these species and electrolyte or along the edge, but a detailed experimental characterization of the mechanism remains elusive. It is thus of particular importance to understand the interplay between doped edges and hydrogenated charge carriers, since this can influence the structure and stability of the charged bilayers and hence provides a key to tuning charge transfer and improving the electrochemical performance.…”

Comparison of surface and bulk nitrogen modification in highly porous carbon for enhanced supercapacitors

“…The amine and/or cyano functional groups in HTMA-C have lone pair electrons, which increase the surface charge density. While NC does contain negatively charged nitrogen groups in the form of pyrrolic and pyridinic nitrogen that can increase conductivity and add pseudocapacitance [27,52], these charges are distributed throughout the bulk rather than remaining only on the surface and therefore do not interact as directly with the electrolyte. Fig.…”

“…Recently, a number of studies reported improved capacitance by using carbon enriched with nitrogen in both aqueous electrolytes [22−27] and organic electrolytes [25,27,28]. Many of these studies incorporate nitrogen into the bulk network as heteroatoms, either through the use of a nitrogen-containing precursor [22,29−32] or modification after carbon synthesis [18,33−37].…”

“…The significantly larger intensity of the peak at 399.8 eV suggests that most of the nitrogen found in this sample is in the form of surface funtionalities. For NC, the peak at 400.9 eV corresponds to pyrrolic nitrogen (N-5) [25,27,38], while the peak at 398.9 eV corresponds to pyridinic nitrogen (N-6) [22,25]. Therefore, while the vast majority of nitrogen groups in HTMA-C are in the form of surface functionalities or a surface-only coating of hexamine, the heat treatment applied to NC helps to incorporate nitrogen into carbon's bulk network in the form of substitutional heteroatoms.…”