Tunable Oxygen Functional Groups as Electrocatalysts on Graphite Felt Surfaces for All-Vanadium Flow Batteries

• Published in: ChemSusChem Vol. 9; no. 12; pp. 1455 - 1461
• Main Authors: Estevez, Luis, Reed, David, Nie, Zimin, Schwarz, Ashleigh M, Nandasiri, Manjula I., Kizewski, James P, Wang, Wei, Thomsen, Edwin, Liu, Jun, Zhang, Ji-Guang, Sprenkle, Vincent, Li, Bin
• Format: Journal Article
• Language: English
• Published: Germany Blackwell Publishing Ltd 22.06.2016; Wiley Subscription Services, Inc; ChemPubSoc Europe
• Subjects: carbon; Catalysis; Degradation; Electric Power Supplies; Electrochemistry; electrode; Electrodes; Environmental Molecular Sciences Laboratory; Functional groups; Graphite; Oxidation-Reduction; Oxygen; Oxygen - chemistry; oxygen functional group; Performance enhancement; plasma chemistry; Plasma Gases - chemistry; Rechargeable batteries; Reduction; Vanadium - chemistry; vanadium flow battery; vanadium flow battery; electrode; plasma chemistry; oxygen functional group; carbon
• ISSN: 1864-5631; 1864-564X
• DOI: 10.1002/cssc.201600198

A dual oxidative approach using O2 plasma followed by treatment with H2O2 to impart oxygen functional groups onto the surface of a graphite felt electrode. When used as electrodes for an all‐vanadium redox flow battery (VRB) system, the energy efficiency of the cell is enhanced by 8.2 % at a current density of 150 mA cm−2 compared with one oxidized by thermal treatment in air. More importantly, by varying the oxidative techniques, the amount and type of oxygen groups was tailored and their effects were elucidated. It was found that O−C=O groups improve the cells performance whereas the C−O and C=O groups degrade it. The reason for the increased performance was found to be a reduction in the cell overpotential after functionalization of the graphite felt electrode. This work reveals a route for functionalizing carbon electrodes to improve the performance of VRB cells. This approach can lower the cost of VRB cells and pave the way for more commercially viable stationary energy storage systems that can be used for intermittent renewable energy storage. Tunable batteries: A dual oxidative approach using O2 plasma followed by treatment with H2O2 was used to tailor the amount and type of oxygen functional groups on the surface of a graphite felt electrode. It was found that O−C=O groups improve the cells performance whereas the C−O and C=O groups degrade it. The reason for the increased performance was found to be a reduction in the cell overpotential after functionalization of the graphite felt electrode.