Expanding the potential window of aqueous electrochemical capacitors with binder-free electrostatically sprayed manganese oxide composite cathode films
Abstract
In this study, three binder-free manganese oxide-carbon nanotube (MnOx-CNT) composite films were synthesized using electrostatic spray deposition (ESD) and evaluated as electrochemical capacitor (EC) electrodes in aqueous media. The MnOx-CNT 9-1 composition exhibited superior electrochemical performance as compared to both the pristine MnOx and MnOx-CNT 8-2 composite films, exhibiting a high specific capacitance of 281 F g-1 in addition to excellent rate handling and cyclability. In order to investigate the practical viability of the MnOx-CNT 9-1 electrodes, a comprehensive two-electrode analysis was performed using activated carbon (AC) counter electrodes for different mass ratios to obtain optimal energy-power trade-off. The asymmetric capacitor with the AC electrode with a mass 2.6 times that of the MnOx-CNT 9-1 electrode exhibited the best energy-power characteristics reaching a maximal gravimetric energy density of 30.3 Wh kg-1; the excellent electrochemical performance of the asymmetric capacitor is attributed to the wider cell voltage of 2V as well as the high gravimetric capacitance of the ESD- based MnOx-CNT composite cathode.
- Publication:
-
Materials Research Express
- Pub Date:
- August 2019
- DOI:
- 10.1088/2053-1591/ab1a24
- Bibcode:
- 2019MRE.....6h5012A
- Keywords:
-
- asymmetric electrochemical capacitors;
- manganese oxide;
- carbon nanotubes;
- electrostatic spray deposition;
- activated carbon