Bougainvillea-Shaped Electrode With Dual-Functionality for Iron-Chromium Redox Flow Battery

Abstract

Iron-chromium redox flow batteries (ICRFBs) are promising for large-scale energy storage but suffer from sluggish Cr³⁺/Cr²⁺ redox kinetics and severe hydrogen evolution reaction (HER) at the anode. To address these issues, a bougainvillea-like indium-doped BiOCl nanosheet architecture on carbon cloth (C-In/BiOCl-CC) was developed as a high-performance electrode. The unique hierarchical structure was found to significantly increase the specific surface area and active sites, thereby facilitating efficient Cr ion conversion. Simultaneously, indium doping effectively suppresses HER by elevating the hydrogen evolution overpotential, while the synergistic effect between In and BiOCl enhances electronic conductivity and reduces charge transfer resistance. As a result, the electrode demonstrates a low Cr³⁺ reduction overpotential of 0.35 V at 140 mA cm^-2 and a charge transfer resistance of 0.492 Ω. The assembled ICRFB achieves an energy efficiency of 84.7% and a voltage efficiency of 86.5% at 140 mA cm^-2, while maintaining stable performance over 800 cycles with coulombic efficiency exceeding 97%. This work offers an effective electrode design strategy for high-performance and long-life ICRFBs.

Keywords

BiOCl catalyst / cycle stability / electrochemical performance / iron-chromium flow batteries / suppression of hydrogen evolution reaction

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2025 The Author(s). Carbon Neutralization published by Wenzhou University and John Wiley & Sons Australia, Ltd.