Oxygen Reduction Kinetics of Fe-N-C Single Atom Catalysts Boosted by Pyridinic N Vacancy for Temperature-Adaptive Zn-Air Batteries.

The design of temperature-adaptive Zn-air batteries (ZABs) with long life spans and high energy efficiencies is challenging owing to sluggish oxygen reduction reaction (ORR) kinetics and an unstable Zn/electrolyte interface. Herein, a quasi-solid-state ZAB is designed by combining atomically dispersed Fe-N-C catalysts containing pyridinic N vacancies (FeNC-V _N ) with a polarized organo-hydrogel electrolyte. First-principles calculation predicts that adjacent V _N sites effectively enhance the covalency of Fe-N _x moieties and moderately weaken *OH binding energies, significantly boosting the ORR kinetics and stability. In situ Raman spectra reveal the dynamic evolution of *O ₂ ^- and *OOH on the FeNC-V _N cathode in the aqueous ZAB, proving that the 4e ^- associative mechanism is dominant. Moreover, the ethylene glycol-modulated organo-hydrogel electrolyte forms a zincophilic protective layer on the Zn anode surface and tailors the [Zn(H ₂ O) ₆ ] ²⁺ solvation sheath, effectively guiding epitaxial deposition of Zn ²⁺ on the Zn (002) plane and suppressing side reactions. The assembled quasi-solid-state ZAB demonstrates a long life span of over 1076 h at 2 mA cm ^-2 at -20 °C, outperforming most reported ZABs.