Nitrogen-Doped Graphene for High-Performance Ultracapacitors and the Importance of Nitrogen-Doped Sites at Basal Planes

Abstract

Although various carbon nanomaterials including activated carbon, carbon nanotubes, and graphene have been successfully demonstrated for high-performance ultracapacitors, their capacitances need to be improved further for wider and more challenging applications. Herein, using nitrogen-doped graphene produced by a simple plasma process, we developed ultracapacitors whose capacitances (∼280 F/g(electrode)) are about 4 times larger than those of pristine graphene based counterparts without sacrificing other essential and useful properties for ultracapacitor operations including excellent cycle life (>200,000), high power capability, and compatibility with flexible substrates. While we were trying to understand the improved capacitance using scanning photoemission microscopy with a capability of probing local nitrogen-carbon bonding configurations within a single sheet of graphene, we observed interesting microscopic features of N-configurations: N-doped sites even at basal planes, distinctive distributions of N-configurations between edges and basal planes, and their distinctive evolutions with plasma duration. The local N-configuration mappings during plasma treatment, alongside binding energy calculated by density functional theory, revealed that the origin of the improved capacitance is a certain N-configuration at basal planes.

Nitrogen-containing chitosan-based carbon as an electrode material for high-performance supercapacitors

“…At low scan rates, NCh2 exhibits the highest capacity value, which agrees with the highest total content of nitrogen-and oxygen-containing functional groups on its surface, based on the XPS results ( Table 2). In addition, this sample possesses the highest content of pyridinic-N (N-6), pyrrolic/pyridonic-N (N-5), and quinone-O (O-I) groups, to whom the pseudocapacitive effect is attributed [33,34]. Hydroxyl groups were also found to contribute to pseudocapacitance [35].…”

Superhigh capacity and rate capability of high-level nitrogen-doped graphene sheets as anode materials for lithium-ion batteries

“…The pyridinic nitrogen atoms could also be beneficial to increase the reversible capacity of the nitrogen-doped graphene electrode, which could be attributed to the stronger electronegativity of nitrogen than that of carbon [20,[25][26][27]. However, the synthetic methods of nitrogen-doped graphene are mainly limited to chemical vapor deposition (CVD) [20], thermal annealing of graphene oxide with NH 3 [28], nitrogen plasma treatment of graphene [29], solvothermal synthesis [30], and the arc-discharge method [31]. The CVD method cannot meet the demand of large scale production of nitrogen-doped graphene [21].…”

Nitrogen-doped reduced graphene oxide electrodes for electrochemical supercapacitors

“…Nitrogen-doped (N-doped) graphene has been demonstrated to be of use as an electrocatalytic material for oxygen reduction in hydrogen fuel cells, 12 improves biocompatibility of carbon devices in biosensing 13 and enhances the performance of graphene-based supercapacitors. 14 Graphene may be synthesised via mechanical cleavage of graphite flakes, 15 Chemical Vapour Deposition (CVD) 16 or the decomposition of silicon carbide (SiC). 17 However, while the latter two have great potential in electronics fabrication, it is not feasible to produce gram-scale quantities using these methods.…”