Heteroatom/flexibility-adaptive carbon electrode via shallow-etching strategy enables long-life zinc-air batteries

Integrating catalytic activity with structural flexibility in self-supported electrodes remains a pivotal challenge for durable zinc-air batteries (ZABs). Herein, a shallow-etching pyrolysis strategy is proposed to synthesize flexible N/S co-doped carbonized cotton cloth (N/S-CCC) electrodes via hydroxyl-mediated thiourea adsorption. Unlike conventional etching methods that compromise mechanical integrity, this approach achieves controlled surface activation while generating self-adaptive N/S species and mechanical flexibility. The optimized N/S-CCC-2 electrode exhibits synergistic heteroatom interactions between pyridinic-N (electron density regulation) and thiophene-S (spin-state modulation), reducing the rate-determining step energies to 0.75 eV for ORR and 0.85 eV for OER. With an ultrahigh surface area (1230 m²·g^-1) and minimized strain, the catalyst exhibits outstanding bifunctional oxygen activity (ΔE = 0.78 V in 0.1 mol·L^-1 KOH), ranking it among the top-tier metal-free catalysts. When employed into aqueous ZABs, the N/S-CCC-2 electrode delivers a peak power density of 255 mW·cm^-2 and ultra-stable cycling over 1000 h. Flexible ZABs further demonstrate mechanical robustness (400 bending cycles) with minimal performance decay, outperforming traditional slurry-coated Pt/C + RuO₂ counterparts. This work establishes a sustainable, metal-free, binder-free paradigm to resolve the catalytic activity-flexibility trade-off in energy storage devices.