A High‐Performance Composite Electrode for Vanadium Redox Flow Batteries

Abstract

A composite electrode composed of reduced graphene oxide‐graphite felt (rGO‐GF) with excellent electrocatalytic redox reversibility toward V2+/V3+ and VO2+/VO2+ redox couples in vanadium batteries was fabricated by a facile hydrothermal method. Compared with the pristine graphite felt (GF) electrode, the rGO‐GF composite electrode possesses abundant oxygen functional groups, high electron conductivity, and outstanding stability. Its corresponding energy efficiency and discharge capacity are significantly increased by 20% and 300%, respectively, at a high current density of 150 mA cm−2. Moreover, a discharge capacity of 20 A h L−1 is obtained with a higher voltage efficiency (74.5%) and energy efficiency (72.0%), even at a large current density of 200 mA cm−2. The prepared rGO‐GF composite electrode holds great promise as a high‐performance electrode for vanadium redox flow battery (VRFB).

Electrocatalysis at Electrodes for Vanadium Redox Flow Batteries

“…Li et al obtained rGO by electrochemical reduction and studied its activity for both positive and negative VRFB electrode reactions [248]. rGO was prepared on graphite felt by a hydrothermal method as reported by Deng et al [249]. The number of oxygen-containing functional groups was vastly increased; the electronic conductivity as well as the stability (more than 500 cycles with almost no efficiency loss) were improved also.…”

Mass Transfer and Reaction Kinetic Enhanced Electrode for High‐Performance Aqueous Flow Batteries

“…The ohmic resistance and the charge transfer polarization strongly depend on the physiochemical properties of the electrodes in the RFBs. The most commonly used electrodes in RFB are graphite felts (GFs) and carbon felts (CFs) by virtue of their high electrical conductivity, excellent stability, high corrosion resistance, and broad operational potential at a reasonable cost . Despite the intensive research efforts, achieving high power density and energy efficiency are still a significant challenge for the RFB due to the hydrophobic nature of electrode arising from the high‐temperature graphitization, poor catalytic activity contributing to higher polarization losses, and lack of abundant redox reaction sites owing to the low specific surface area …”

KHCO3 activated carbon microsphere as excellent electrocatalyst for VO2+/VO2+ redox couple for vanadium redox flow battery

“…Firstly, cross-contaminating of active species can be eliminated as VRFB employs the electrolyte using the same vanadium element as active species. Then, VRFB stores energy in electrolyte independent of the cell stack, and can meet the need of largescale energy storage, with long cycling life and high efficiency in large installations [12][13][14][15][16][17] . Finally, the operating environment of VRFB is relatively safe without rigorous requirements.…”