Redox enhanced energy storage in an aqueous high-voltage electrochemical capacitor with a potassium bromide electrolyte
Journal article, 2017

This paper reports a detailed electrochemical investigation of a symmetric carbon-carbon electrochemical device with a potassium bromide (KBr) electrolyte. Below 1.6 V, KBr gives electrochemical double layer behavior. At higher voltages the Br-/Br-3 redox reaction comes into effect and enhances the energy storage. The redox-enhanced device has a high energy density, excellent stability, as well as high coulombic and energy efficiencies even at 1.9 V. More importantly, the redox contribution can be “triggered” by pre-cycling at 1.9 V, and remains beneficial after switching to 1.6 V. The triggering operation leads to a 22% increase in stored energy with negligible sacrifice of power. The intriguing behavior is accompanied by a series of complex variations including the shifts of electrode potential limits and the shift of potential of zero voltage. The electro-oxidation of the positive electrode and kinetics of the Br-/Br-3 electrode reactions are proposed to be the main causes for the triggering phenomenon. These findings provide means to improve the design and operation of devices that contain bromine, or other redox species with a comparably high electrode potential.

redox electrolyte

aqueous supercapacitor

electrode potential

high voltage

Redox-EDLC

Author

Qi Li

Chalmers, Microtechnology and Nanoscience (MC2), Electronics Material and Systems Laboratory

Mohammad Mazharul Haque

Chalmers, Microtechnology and Nanoscience (MC2), Electronics Material and Systems Laboratory

Volodymyr Kuzmenko

Chalmers, Microtechnology and Nanoscience (MC2), Electronics Material and Systems Laboratory

Namrata Ramani

University of California

Per Lundgren

Chalmers, Microtechnology and Nanoscience (MC2), Electronics Material and Systems Laboratory

Anderson David Smith

Chalmers, Microtechnology and Nanoscience (MC2), Electronics Material and Systems Laboratory

Peter Enoksson

Wallenberg Wood Science Center (WWSC)

Chalmers, Microtechnology and Nanoscience (MC2), Electronics Material and Systems Laboratory

Journal of Power Sources

0378-7753 (ISSN)

Vol. 348 219-228

Driving Forces

Sustainable development

Areas of Advance

Nanoscience and Nanotechnology (2010-2017)

Transport

Production

Energy

Materials Science

Subject Categories

Materials Chemistry

Electrical Engineering, Electronic Engineering, Information Engineering

DOI

10.1016/j.jpowsour.2017.02.082

More information

Latest update

9/21/2018