Flame modified carbon-based electrodes as positive electrode for high performance of hydrogen/iron battery

The electrode is a core component that affects the overall performance of the hydrogen/iron redox flow battery. To address the drawbacks associated with the limited electrochemical activity and fewer active sites of the carbon-based electrode, this study employs a straightforward and effective flame method to synthesize carbon nanotubes (CNTs) on carbon paper and NiO/CNT composite on graphite felt. The CNT on the modified carbon-based electrode contains many hydrophilic and oxygen-containing functional groups, greatly improving the hydrophilicity of the electrode, thereby increasing the electrochemical surface area. The modified carbon-based electrode exhibits better electrochemical activity due to the CNT or NiO/CNT providing more active sites. At 50 mA cm−2, the energy efficiency of pristine carbon paper and graphite felt is 60.8% and 52.4%, respectively, while the energy efficiency of the modified carbon paper and graphite felt reached 75.3% and 80.5%, respectively. The modified carbon-based electrode achieves a 100% coulombic efficiency, with no significant degradation in energy efficiency after running for 300 cycles, demonstrating excellent stability. This study not only investigates the performance of graphite felt electrodes in hydrogen/iron batteries but also proposes a flame method for preparing CNT-modified carbon-based electrodes for high-performance hydrogen/iron batteries. •A simple and efficient flame method has been proposed for growth of CNT on carbon paper and NiO/CNT composite on graphite felt•The coulombic efficiency of modified carbon-based electrode has been achieved at 100% and operate stably for 300 cycles.•A possible catalytic mechanism for the redox reaction of Fe2+/Fe3+ was proposed.•This work provides a reference for the selection of electrodes, contributing to the future development of hydrogen/iron batteries.