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Vanadium Redox Flow Battery: A Promising Large-Scale Energy Storage Device

Large-scale energy storage systems based on vanadium redox flow batteries (VRFBs) are developed for the deployment of renewable energy technologies. VRFB is easy to scale and the energy and power can be decoupled. The materials used for the electrode have a crucial role on the performance of VRFB. It is reported that the pre-treatment of the electrode increases the hydrophilicity and creates functional groups (carbonyl, carboxyl and hydroxyl) on the electrode surface, thereby influencing the kinetics. The figure below presents the performance of VRFB with untreated and electrochemically treated Toray carbon papers (CPs). The electrochemically generated functional groups on CP can be confirmed by XPS. It is found that the asymmetrically configured cell with CP_2.0 V_15 min_-1.0 V_10 min at the positive electrode and CP_2.0 V_15 min at the negative electrode offers maximum power density of ~325 mW cm-2, and it is much higher than that of symmetric cell using untreated CP electrodes (~85 mW cm-2).

[Note: CP_2.0 V_15 min_-1.0 V_10 min indicates CP electrode after the initial treatment at +2.0 V for 15 min treated subsequently at -1.0 V for 10 min].

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Figure: Polarization and power density curves recorded with a 5 cm2 VRFB with electrochemically
treated and untreated CP electrodes at a flow rate of 20 mL min-1.
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Figure: Schematic of Vanadium redox flow battery.

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Prof. Manoj
Prof. Anand