Hybrid MnO2/carbon nanotube-VN/carbon nanotube supercapacitors

•VN/multiwalled carbon nanotube (MWCNT) fibrous composites were fabricated.•VN/MWCNT composites showed good capacitive behavior in Na2SO4 electrolyte.•Good capacitive behavior and cycling stability were achieved at high electrode mass.•Quartz crystal microbalance data provide an insight into the charging mechanism.•Aqueous MnO2/MWCNT-VN/MWCNT supercapacitors were tested in a voltage window of 1.8 V.

Composite materials, containing fibrous VN nanoparticles and multiwalled carbon nanotubes (MWCNT) are prepared by a chemical method for application in electrochemical supercapacitors. We demonstrate for the first time that VN-MWCNT electrodes exhibit good capacitive behavior in 0.5 M Na2SO4 electrolyte in a negative voltage window of 0.9 V. Quartz crystal microbalance studies provide an insight into the mechanism of charge storage. Composite VN-MWCNT materials show significant improvement in capacitance, compared to individual VN and MWCNT materials. Testing results indicate that VN-MWCNT electrodes exhibit high specific capacitance at high mass loadings in the range of 10–30 mg cm−2, good capacitance retention at scan rates in the range of 2–200 mV s−1 and good cycling stability. The highest specific capacitance of 160 F g−1 is achieved at a scan rate of 2 mV s−1. The new findings open a new and promising strategy in the fabrication of hybrid devices based on VN. The proof-of-principle is demonstrated by the fabrication of hybrid supercapacitor devices based on VN-MWCNT negative electrodes and MnO2 –MWCNT positive electrodes with voltage window of 1.8 V in aqueous 0.5 M Na2SO4 electrolyte. The hybrid VN-MWCNT/MnO2-MWCNT supercapacitor cells show promising capacitive and power-energy characteristics.

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