The redox-active electrolyte supercapacitor (RAES) is a relatively new type of energy storage device. Simple addition of selected redox species in the electrolyte can greatly enhance the energy density of supercapacitors relative to traditional electric double layer capacitors (EDLCs) owing to redox reactions. Studies on the kinetics at the interface of the electrode and redox mediator are important when developing RAESs. In this work, we employ highly accurate scanning electrochemical microscopy (SECM) to extract the kinetic constants at carbon/hydroquinone interfaces. The charge transfer rate constants are 1.2 × 10-2 and 1.3 × 10-2 cm s-1 for the carbon nanotube/hydroquinone and reduced graphene oxide/hydroquinone interfaces, respectively. These values are higher than those obtained by the conventional cyclic voltammetry method, approximately by an order of magnitude. The evaluation of heterogeneous rate constants with SECM would be the cornerstone for understanding and developing high performance RAESs.
Bibliographical noteFunding Information:
This work was financially supported by the Brain Korea 21 Plus Project in 2014 and the National Research Foundation of Korea (NRF-2017R1A2B2006209). Part of the work was supported by grant no. MOE2015-T2-1-129 awarded by the Ministry of Education, Singapore.
© 2017 American Chemical Society.
- Carbon nanotube
- Charge transfer kinetics
- Redox-active electrolyte
- Reduced graphene oxide
- Scanning electrochemical microscopy
ASJC Scopus subject areas
- General Materials Science