Boosting the pseudocapacitance of nitrogen-rich carbon nanorod arrays for electrochemical capacitors

Abstract

The ultrahigh N content (∼24%) induced by the low-temperature treatment boosts the pseudocapacitance for carbonaceous materials.

Heteroatom‐Doped and Oxygen‐Functionalized Nanocarbons for High‐Performance Supercapacitors

“…[65][66][67] For example, N-rich carbon nanorods prepared by pyrolysis of polyaniline (PANI) nanorod arrays and ammonium sulfate have exhibited specific capacitance of 776 F g −1 at 1 A g −1 with 94.4% retention at 40 A g −1 after 5000 charge-discharge cycles versus reference electrode whereas PANI nanorod arrays showed the capacitance of 408.36 F g −1 at 1 A g −1 with 49.19% retention after 500 cycles. [68] In addition, heteroatom doped nanocarbons have several key features over pseudocapacitive materials while they are utilized as a supercapacitor electrode as follows:…”

“…An enhancement in the specific capacitance of the electrode is found to have a linear relationship with N-content up to 7 wt% in 1 m aqueous H 2 SO 4 electrolyte and diluted tetraethylammonium tetrafluoroborate (TEABF 4 ) in propylenecarbonate (PC). [126] Significant efforts have been undertaken to increase the N-content by 29.82 at% in graphitic materials by fluorination (with XeF 2 in Teflon container at 200 °C for 30 h in Ar) followed by the annealing treatment, [37] 45% N/C doped carbons derived from melamine, [127] 21.86 at% in nitrogenrich carbon nanorod arrays by low-temperature pyrolysis using PANI nanorod arrays and ammonium sulfate, [68] and some other methods. It is important to note that the specific capacitance of N-doped nanocarbons is limited to 128.2 F g −1 with 45% N/C, [127] 390 F g −1 at 5 A g −1 with 29.82 at% N 2 , [37] and 203.8 F g −1 at 0.1 A g −1 with 9.7 at% N 2 .…”

“…[89] Thus, the presence of N-6 and N-5 configurations is attributed for the excellent capacitive properties of N-rich carbon nanorods with the gravimetric capacitance of 707.58 F g −1 at 2 A g −1 in 1 m H 2 SO 4 and 553.12 F g −1 KOH at 2 A g −1 than in 1 m Na 2 SO 4 (3E). [68] The redox reactions of N-6 and N-5 groups are suppressed in the alkaline medium due to the lack of protons in an electrolyte and their basic nature. [89] Since the charge-distribution is different for each N-configuration, they have a difference in reduction/oxidation since, for example, N-X is an oxidizing agent (−0.264e) whereas N-6 is a reducing agent (+0.23e).…”

Synthesis of a Novel Petal‐Shaped Biomass‐Derived Carbon Material with Controlled Pore Structure and Nitrogen Content for Use in Supercapacitors

“…Li et al and Arrigo et al [26,27] experimentally demonstrated that the Ocontaining functional groups in the precursors could react with some N-containing substance to form CÀ N bond. Yang et al [28] further research indicated that these reactions could occur at 300~500°C. Inspired by these points, utilizing the feature of high O content of biomass-based activated carbon materials, the capacitance can be further improved by introducing of N elements to the surface of activated biomass-based carbon materials.…”

“…experimentally demonstrated that the O‐containing functional groups in the precursors could react with some N‐containing substance to form C−N bond. Yang et al . further research indicated that these reactions could occur at 300∼500 °C.…”