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Tactical Surface Modification of a 3D Graphite Felt as an Electrode of Vanadium Redox Flow Batteries with Enhanced Electrolyte Utilization and Fast Reaction Kinetics
journal contribution
posted on 2020-03-25, 20:08 authored by Rajeev
K. Gautam, Manshu Kapoor, Anil VermaThree-dimensional
porous carbon materials have great importance
as electrode materials for vanadium redox flow batteries due to electrochemical
stability over a wide potential window and low cost. However, sluggish
electrode kinetics toward vanadium redox reactions makes electrode
treatment vital before its use in a vanadium redox flow battery. Researchers
have used different routes to modify the graphite electrode surface.
This article presents a very simple (and known) but tactical procedure
to treat a graphite felt. The modified electrode possesses large surface
area having well-developed uniform pore structures and abundant oxygen-rich
surface functional groups (11.2%), which offers a significant reduction
in peak separation potential and charge-transfer resistance with a
noteworthy improvement in the peak current density and redox reaction
reversibility compared to a bare graphite felt. The modified graphite
felt electrode enables 14- and 19-fold improvements in exchange current
toward VO2+/VO2+ and V3+/V2+ redox reactions,
respectively, than those of a bare graphite felt. The battery performance
at 50 mA cm–2 of current density displays energy
efficiency (89%) and electrolyte utilization (89%) nearly 12 and 98%,
respectively, higher than that of a bare graphite felt. The long-term
performance (200 cycles) of the battery assured stable behavior of
the modified electrode. Moreover, the present modified approach improves
the peak power density by 3-fold compared to that of the bare graphite
felt.
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Keywords
surface areaelectrochemical stabilityoxygen-rich surfacevanadium redox flow batteryEnhanced Electrolyte Utilizationpeak power densityVanadium Redox Flow Batteries3 D Graphite Feltcarbon materialsvanadium redox reactionselectrode materialsTactical Surface Modificationvanadium redox flow batteriescharge-transfer resistanceFast Reaction Kinetics Three-dimensionalelectrode treatmentelectrode kineticsVOuniform pore structuresbattery performanceredox reaction reversibilitypeak separationgraphite electrode surface
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