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.