Engineering Graphene Oxide-Incorporated Iron Vanadate Nanocomposites as Electrode Material for High-Performance Redox Flow Battery and Supercapacitor Performances

Increasing energy demands in recent days have emphasized the need for development of reliable and efficient energy storage/conversion materials. Thereby, iron vanadate (FeVO₄) was synthesized using a facile hydrothermal method, which is known to exhibit superior redox activity but its poor conductivity and low charge transfer process affect overall performance. Incorporation of graphene oxide into FeVO₄ enhances the conductivity, overall stability, and redox activity of a composite due to a synergetic effect. Thereby, a multifunctional advanced electrocatalyst can be obtained. Spectroscopic techniques including X-ray diffraction, FE-SEM, EDAX-elemental mapping, Raman, X-ray photoelectron spectroscopy, and HR-TEM analysis were done to validate the successful production of high-purity products. The synthesized materials were subjected to various electrochemical studies to validate the electrochemical activity. The composite material was used as an electrode with an area of 132 cm² in redox flow batteries. The constructed vanadium flow battery cell exhibited a Coulombic efficacy of 93% and Voltaic efficacy of 88% at a current rating of 70–17.5 mA/cm² for the first time and was stable for 1000 cycles. Similar studies were conducted for an iron flow battery, resulting in 89% Coulombic efficiency along with a discharge capacity of 2456 mA h. Supercapacitor studies were conducted by depositing a slurry of composite on a carbon sheet. The electrode exhibited 1374 F/g at 12.5 A/g in charge–discharge studies and 1194 F/g from EIS analysis, establishing appreciable capacitance of 197 F/g at a very high current of 100 A/g and exhibiting a wider current range. These studies highlight the superior behavior of the material in multiple domains of energy storage devices.