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-VN) with a polarized organo-hydrogel electrolyte. First-principles calculation predicts that adjacent VN sites effectively enhance the covalency of Fe–Nx moieties and moderately weaken *OH binding energies, significantly boosting the ORR kinetics and stability. In situ Raman spectra reveal the dynamic evolution of *O2– and *OOH on the FeNC-VN 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(H2O)6]2+ solvation sheath, effectively guiding epitaxial deposition of Zn2+ 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.