Amorphous Zr-based MOF engineered carbon felt electrodes for high-performance all-Iron flow batteries with enhanced areal capacity

All‑iron redox flow batteries (AIRFBs) represent a compelling solution for grid-scale energy storage due to their cost-effectiveness, material abundance, and environmental compatibility. However, the limited electrochemical activity and sluggish reaction kinetics of conventional carbon felt electrodes at the negative side severely restrict the areal capacity and lifespan of AIRFBs. This study addresses these limitations through rational design of amorphous zirconium-based metal-organic framework (ZrATMP) catalysts synthesized via a single-step solvothermal process. The ZrATMP-modified carbon felt (Zr@CF) electrode with microporous structure provides abundant active sites and facilitates electrolyte transport, significantly enhancing the electrochemical activity of the electrode. Moreover, the composite electrode also effectively suppresses hydrogen evolution side reactions through elevated energy barriers while promoting uniform Fe deposition. Benefiting from the synergistic effects, the assembled full cell achieves stable operation over >300 h at 20 mA cm −2 /20 mAh cm −2 with 99 % Coulombic efficiency. More importantly, it also sustains unprecedented cyclability at 40 mAh cm −2 —a benchmark areal capacity demonstrating practical viability. This study establishes amorphous MOF catalysts for high-performance AIRFBs, resolving the critical trade-off between cycle longevity and energy density in flow battery systems.