Engineering Graphene\nOxide-Incorporated Iron Vanadate\nNanocomposites as Electrode Material for High-Performance Redox Flow\nBattery and Supercapacitor Performances

Increasing energy demands in recent days have emphasized\nthe need\nfor development of reliable and efficient energy storage/conversion\nmaterials. Thereby, iron vanadate (FeVO<sub>4</sub>) was synthesized\nusing a facile hydrothermal method, which is known to exhibit superior\nredox activity but its poor conductivity and low charge transfer process\naffect overall performance. Incorporation of graphene oxide into FeVO<sub>4</sub> enhances the conductivity, overall stability, and redox activity\nof a composite due to a synergetic effect. Thereby, a multifunctional\nadvanced electrocatalyst can be obtained. Spectroscopic techniques\nincluding X-ray diffraction, FE-SEM, EDAX-elemental mapping, Raman,\nX-ray photoelectron spectroscopy, and HR-TEM analysis were done to\nvalidate the successful production of high-purity products. The synthesized\nmaterials were subjected to various electrochemical studies to validate\nthe electrochemical activity. The composite material was used as an\nelectrode with an area of 132 cm<sup>2</sup> in redox flow batteries.\nThe constructed vanadium flow battery cell exhibited a Coulombic efficacy\nof 93% and Voltaic efficacy of 88% at a current rating of 70–17.5\nmA/cm<sup>2</sup> for the first time and was stable for 1000 cycles.\nSimilar studies were conducted for an iron flow battery, resulting\nin 89% Coulombic efficiency along with a discharge capacity of 2456\nmA h. Supercapacitor studies were conducted by depositing a slurry\nof composite on a carbon sheet. The electrode exhibited 1374 F/g at\n12.5 A/g in charge–discharge studies and 1194 F/g from EIS\nanalysis, establishing appreciable capacitance of 197 F/g at a very\nhigh current of 100 A/g and exhibiting a wider current range. These\nstudies highlight the superior behavior of the material in multiple\ndomains of energy storage devices.