Molecular-Bridge-Directed Thermal Reconstruction of Semiconfined Fe-Based Sites in Dual-Carbon Matrix Enabling Long-Term Zinc-Air Batteries

To resolve the critical trade-off between anchoring stability and active-site accessibility in flexible zinc-air batteries, this work proposes a molecular-bridged reconstruction strategy. Employing urea molecular bridging and thermally driven reconstruction (carbon-collapse-metal-migration), we engineer semiembedded Fe-based active sites in a dual-carbon armored architecture (NC/Fe/NCF) composed of a flexible carbon fiber substrate with a protective N-doped outer layer through thermally driven carbon reconstruction. This unique semiexposed/semiconfined configuration ensures interfacial accessibility while preventing active-center leaching, eliminating binders and current collectors. The optimized dual-carbon architecture achieves a high surface area (905 m²·g⁻¹), stabilized active species, and enhanced electron conductivity. The resultant self-supported electrode delivers superior ORR performance with a 0.89 V half-wave potential (exceeding Pt/C by 30 mV) and merely 8 mV decay after 10,000 cycles. When deployed in liquid zinc-air batteries, it enables ultrastable operation for >1300 h (2600 cycles). Critically, the flexible battery achieves a 1.38 V open-circuit voltage and 58 mW·cm⁻² peak power density and sustains 500 cycles without failure. By integrating toxic-solvent-free green synthesis with structural innovation, this work develops scalable robust flexible energy storage toward sustainable electronics.