Fabrication of Surface-Nanostructured Carbon Felt Electrodes via an Etching−Pyrolysis Reaction Strategy for High-Performance Vanadium Redox Flow Batteries

High Resolution Image Download MS PowerPoint Slide An etching–pyrolysis reaction (EPR) process was developed to fabricate surface-nanostructured carbon felt (SN-CF) electrodes featuring a uniformly distributed nanoporous architecture decorated with carbon nanoparticles. The resulting electrodes exhibit high specific surface area, superior hydrophilicity, and low electrochemical impedance, leading to enhanced electrochemical activity and improved vanadium redox flow battery (VRFB) performance. Following EPR treatment, the water contact angle decreased from 122.55 to 0°, indicating complete wettability, while the Brunauer–Emmett–Teller (BET) surface area increased from 0.72 to 11.45 m 2 /g, providing abundant active sites for redox reactions. The charge-transfer resistance ( R ct ) was significantly reduced from 58.37 to 5.36 Ω, accompanied by a decrease in internal resistance from 138.4 to 37.1 mΩ, indicating accelerated reaction kinetics. At 50 mA/cm 2, the VRFB with pristine CF electrodes delivers a discharge capacity of 17.2 Ah/L and an energy efficiency (EE) of 73.5%, whereas the SN-CF-based VRFB achieves 34.5 Ah/L and 86.5%. It also maintains high capacities and EEs across 50–250 mA/cm 2 . Moreover, the SN-CF electrodes demonstrate excellent reproducibility and durability, with only 3.6% EE degradation after 500 cycles at 250 mA/cm 2 . These results highlight the EPR strategy as an effective and scalable approach for developing high-performance CF electrodes for VRFBs.