Carbon felt coated with tungsten-bismuth-based oxides as highly active and selective negative electrodes for high power density all-vanadium redox flow batteries

Funding Sponsor

American University in Cairo

Author's Department

Chemistry Department

Second Author's Department

Chemistry Department

Third Author's Department

Energy Materials Laboratory

Fourth Author's Department

Chemistry Department

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https://doi.org/10.1039/d5ta00882d

All Authors

Mostafa M. Omran Taher Al Najjar Nageh K. Allam Ehab N. El Sawy

Document Type

Research Article

Publication Title

Journal of Materials Chemistry A

Publication Date

5-6-2025

doi

10.1039/d5ta00882d

Abstract

All-vanadium redox flow batteries (VRFBs) are one of the future strategic energy storage technologies for large-scale applications. For developing the VRFB negative electrode, tungsten/bismuth-based oxides (W-Bi) were solvothermally synthesized and grown on carbon felt (Wx-Biy@CF) using different initial W/Bi molar ratios. X-ray diffraction (XRD) and Raman spectroscopy results revealed the presence of BiOCl, WO3−x, and Bi2WO6 at various ratios, according to the W to Bi initial molar ratio. The XPS results indicated the oxygen-defective nature of WO3−x and the significant electronic effect between Bi and WO3−x that increases on increasing the Bi contents. Even though all the Wx-Biy@CF electrodes exhibited high catalytic activity for the V2+/V3+ redox reaction, the W-Bi2@CF electrode showed superior catalytic activity and selectivity, indicated by the suppressed hydrogen evolution reaction (HER) and high reversibility. The CV results showed an anodic peak current (Ipa) of 95.8 mA cm−2, a peak potential separation (ΔE) of 83.5 mV, and an anodic to cathodic peak current ratio (Ipa/Ipc) of ≈ 1 at a scan rate of 5 mV s−1. The EIS results, with the distribution of relaxation time (DRT) calculations, showed that the W-Bi2@CF electrode has minimal charge transfer resistance (95.6 mΩ) among the different electrodes. The assembled devices of the W-Bi@CF electrodes showed outstanding stability during 1000 cycles for the negative electrode, with a VE of 89.8 and EE of 83.8 at a current density as high as 250 mA cm−2, indicating the high potential for employing the W-Bi2@CF electrode as a negative electrode in VRFBs.

First Page

21707

Last Page

21724

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