Boosting the volumetric capacitance of MoO3-x free-standing films with Ti3C2 MXene. (20th February 2021)

• Record Type: Journal Article
• Authors: Zheng, Wei; Halim, Joseph; Etman, Ahmed S.; Ghazaly, Ahmed El; Rosen, Johanna; Barsoum, Michel W.
• Is Part Of: Electrochimica acta. Volume 370(2021)
• Publication Date: 2021-02-20
• Subjects: MXene -- MoO3-x -- Free-standing film -- Supercapacitor -- LiCl electrolyte; Electrochemistry -- Periodicals; Electrochemistry, Industrial -- Periodicals; 541.37
• DOI: 10.1016/j.electacta.2020.137665
• Languages: English
• ISSNs: 0013-4686

Abstract

Highlights: MoO3-x /Ti3 C2 MXene free-standing films show high volumetric capacitances with excellent cyclability. The asymmetric supercapacitors delivered maximum energy density of 48.6 Wh L −1 with outstanding output voltage (2.1 V). The impressive electrochemical performance, low cost and green nature bode well for practical applications. Abstract: The high theoretical capacitance of molybdenum trioxide (MoO3 ) renders it an attractive supercapacitor electrode material. However, its low electronic conductivity restricts charge transfer and slows its reaction kinetics. Herein, we vacuum filtered porous, free-standing, flexible and highly conductive films comprised of oxygen vacancy-rich MoO3-x nanobelts and delaminated Ti3 C2 MXene in a mass ratio of 80:20, respectively. When tested as supercapacitor electrodes, in a 5 M LiCl electrolyte, volumetric capacitances of 631 F cm −3 at 1 A g −1, and 474 F cm −3 at 10 A g −1 were obtained. To increase the energy density, asymmetric supercapacitors, wherein the anodes were MoO3 -based and the cathodes were nitrogen-doped activated carbon were assembled and tested. The resulting volumetric energy density was 48.6 Wh L −1 . After 20, 000 continuous charge/discharge cycles at 20 A g −1, 96.3 % of the initial charge remained. These values are outstanding for free-standing supercapacitor electrodes, especially in aqueous electrolytes.