Activated Carbon-Coated Carbon Nanotubes for Energy Storage in Supercapacitors and Capacitive Water Purification

Abstract

Polypyrrole-coated multiwalled carbon nanotubes (PPy-MWCNT) were used for the fabrication of activated carbon-coated MWCNT doped with nitrogen (N-AC-MWCNT). The conceptually new method for the fabrication of non-agglomerated PPy-MWCNT with good coating uniformity allowed the fabrication of uniform and welldispersed N-AC-MWCNT with high surface area. The use of N-AC-MWCNT allowed the fabrication of supercapacitor electrodes with high mass loading in the range of 15−35 mg cm −2 and with a high active material to current collector mass ratio of 0.21−0.50. The N-AC-MWCNT electrodes showed excellent electrochemical performance in aqueous 0.5 M Na 2 SO 4 electrolyte. The maximum specific capacitance of 3.6 F cm −2 (103.1 F g −1 ) was achieved for mass loading of 35 mg cm −2 at a scan rate of 2 mV s −1 . The aqueous supercapacitor cells, based on N-AC-MWCNT electrodes, exhibited excellent performance with energy density of 16.1 mWh g −1 , power density of 14.4 W g −1 , and enlarged voltage window of 1.8 V. The individual electrodes and cells showed good capacitance retention at high charge−discharge rates and good cycling stability. Moreover, the N-AC-MWCNT electrodes showed promising performance for capacitive deionization of water. The feasibility of capacitive removal of organic dyes from aqueous solutions has been demonstrated. A quartz crystal microbalance method was used as a tool for the analysis of electrosorption and electrodesorption of ions and charged dyes during charge and discharge.

Graphitized hierarchical porous carbon nanospheres: simultaneous activation/graphitization and superior supercapacitance performance

“…The contributions to ESR include resistance of the electrolyte solution, the intrinsic resistance of active material and the contact resistance of the electrode interface /current collector. 46 The C' data presents improved capacitance retention at higher frequencies for PCNS-2 materials, compared with PCNS and CNS electrodes. Consequently, it is evident that GPCNS-2 exhibits a lowest ESR value in all samples.…”

Nitrogen-doped porous carbon derived from a bimetallic metal–organic framework as highly efficient electrodes for flow-through deionization capacitors

“…Carbon materials have been found to be the ideal candidates as the CDI electrode. To date, various forms of carbon materials such as activated carbon (AC), 10 carbon aerogel, 11 ordered mesoporous carbon, 12,13 carbon nanotube, [14][15][16] graphene, [17][18][19] and their composites 20,21 have been extensively investigated for CDI electrodes by our research group and others in order to enhance the desalination performance. Despite these major advances, it is still of great urgency to develop highly efficient electrode materials in the current CDI research.…”

Lignosulphonate-cellulose derived porous activated carbon for supercapacitor electrode

“…45 Therefore, a twoelectrode symmetric supercapacitor was assembled with HAPC-11-900 as the electrode material in the 6 M KOH aqueous electrolyte, as shown in Figure 4. 46 An energy density of 1.0 Wh kg -1 at a power density of 14.4 kW kg -1 has been reported for the activated carbon-coated carbon nanotubes, 47 and an energy density of 12.5 Wh kg -1 at a power density of 17 kW kg -1 was observed for the glucose-derived micropores carbon. The Nyquist plot obtained from the two-electrode cell in Figure 4b can be fitted with the equivalent circuit model in Figure S11.The ohmic resistance and the charge transfer resistance were estimated to be 2.2 Ω and 3 Ω, respectively.…”