MnO2 nanosheets synthesized on nitrogen-doped vertically aligned carbon nanotubes as a supercapacitor electrode material

• Published in: Journal of alloys and compounds 2022-12, Vol.925, p.166570, Article 166570
• Main Authors: Yesilbag, Yasar Ozkan, Tuzluca Yesilbag, Fatma Nur, Huseyin, Ahmad, Salih, Ahmed Jalal Salih, Ertugrul, Mehmet
• Format: Article
• Language: English
• Subjects: Capacitance; Carbon; Carbon cloth (CC); Carbon nanotubes; Charge transfer; Chemical vapor deposition; Current density; Discharge; Electrical resistivity; Electrode materials; Electrodes; Energy storage; Floating catalyst chemical vapor deposition (FCCVD); Manganese dioxide; MnO2; N-VACNT; Nanocomposites; Nanosheets; Nitrogen; Stability; Supercapacitors; Synergistic effect
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2022.166570

In the present study, nitrogen-doped vertically aligned carbon nanotubes (N-VACNTs) were synthesized on carbon cloth (CC) using the floating catalyst chemical vapor deposition (FCCVD) method, and MnO2 nanosheets were grown on them using the hydrothermal method to produce an N-VACNT@MnO2 nanocomposite structure. In this structure, a synergistic effect was obtained by combining N-VACNTs, which allow high electrical conductivity and fast ion transfer. In the galvanostatic charge-discharge (GCD) measurements performed separately in a three-electrode test cell using 1 M of Na2SO4 electrolyte, the specific capacitance of the N-VACNTs was found to be 53.7 F g−1 at a current density of 0.5 A g−1, and the specific capacitance of the N-VACNT@MnO2 electrode structure was found to be 497 F g−1. In addition, after 10,000 charge-discharge cycles at a current density of 10 A g−1, the N-VACNT electrode retained 99 % of its initial specific capacitance, while the N-VACNT@MnO2 electrode exhibited outstanding cyclic stability with 76 % of its initial specific capacitance. Moreover, in the as-fabricated asymmetric supercapacitor (ASC) using N-VACNTs and N-VACNTs@MnO2, the negative and positive electrodes achieved a stable voltage window of 0–1.7 V, with a specific capacitance of 59.4 F g−1 at a current density of 1 A g−1. Additionally, this ASC showed good cycling stability retaining 84 % of its specific capacitance at the end of 10,000 cycles. Therefore, this ASC structure with an energy density of 24.7 Wh kg−1 and a power density of 15.7 kW kg−1 are promising electrode materials for energy storage. •Composite N-VACNT@MnO2 were synthesized via FCCVD and hydrothermal methods.•N-VACNT@MnO2 electrode has a specific capacitance of 497 F g−1 and 76 % capacitance retention.•The synergetic effect of N-VACNTs and MnO2 nanosheets improves electrochemical performance.•The assembled ASC device achieved an energy density of 24.7 Wh kg−1.