Understanding the Operating Mechanism of Aqueous Pentyl Viologen/Bromide Redox-Enhanced Electrochemical Capacitors with Ordered Mesoporous Carbon Electrodes
Journal article, 2021

Compared to traditional electric double-layer capacitors, redox-enhanced electrochemical capacitors (redox-ECs) show increased energy density and steadier power output thanks to the use of redox-active electrolytes. The aim of this study is to understand the electrochemical mechanisms of the aqueous pentyl viologen/bromide dual redox system at the interface of an ordered mesoporous carbon (CMK-8) and improve the device performance. Cells with CMK-8 carbon electrodes were investigated in several configurations using different charging rates and potential windows. The pentyl viologen electrochemistry shows a mixed behavior between solution-based diffusion and adsorption phenomena, with the reversible formation of an adsorbed layer. The extension of the voltage window allows for full reduction of the viologen molecules during charge and a consequent increase in the specific discharge energy delivered by the cell. Investigation of the mechanism indicates that a 1.5 V charging voltage with a 0.5 A g-1 charging rate and fast discharge rate produces the best overall performance.

mesoporous carbon

viologen anolyte

redox electrolytes

supercapacitors

aqueous hybrid electrochemical capacitors

Author

Giulio Calcagno

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Applied Surface Chemistry

Brian Evanko

University of California

G.D. Stucky

University of California

Elisabet Ahlberg

University of Gothenburg

Seung Joon Yoo

Gwangju Institute of Science and Technology

Anders Palmqvist

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Applied Surface Chemistry

ACS Applied Materials & Interfaces

1944-8244 (ISSN) 1944-8252 (eISSN)

Vol. In Press

Energy AND Power: Hybrid Supercapacitors

Swedish Energy Agency (39045-1), 2015-01-01 -- 2018-12-31.

Subject Categories

Materials Chemistry

Other Chemical Engineering

Other Chemistry Topics

DOI

10.1021/acsami.1c13378

More information

Latest update

11/2/2021