Unveiling Structure‐Activity Relationship of Polyoxometallate‐Confined Single Atom Electrocatalyst and Polyoxometallate‐Modified Multifunctional Separator for Neutral Zn‐Air Batteries

Abstract The practical application of neutral Zn‐air batteries (ZABs) is severely hindered by sluggish kinetics of oxygen reduction/evolution reaction (ORR/OER) and dendrite growth on the Zn anode. A precisely controlled preparation of Fe single atoms (FSAs) is achieved on a Fe‐substituted H ₃ PW ₁₂ O ₄₀ ∙nH ₂ O (abbr. {FePW ₁₁ O ₃₉ }) dotted Co/N doped carbon (Co‐N‐C), which ensures a well‐dispersed, stable, and high loading (3.55%) of FSAs because the pore size (≈1 nm) of Co‐N‐C) is similar to the diameter of {FePW ₁₁ O ₃₉ }. FSAs show high ORR half‐wave potential (0.824 V) and low OER potential (1.52 V) at 10 mA cm ⁻² in neutral electrolyte. Density functional theory (DFT) calculations indicate that 4‐fold hollow sites on {FePW ₁₁ O ₃₉ } are the most energetically favorable sites for ORR/OER, and the rate‐determining step is *OH↔*O. Dimethyloctadecyl [3‐(trimethoxysilyl) propyl] ammonium chloride groups are modified on polyvinylidene fluoride and then electrostatically connected with H ₃ PW ₁₂ O ₄₀ ∙nH ₂ O anions to form a separator. The long chain groups and H ₃ PW ₁₂ O ₄₀ ∙nH ₂ O promote OH ⁻ transfer and minimize dendrite growth, confirmed by DFT. Solid ZABs with the FSA cathode and separator exhibit excellent performance within 60 to −60 °C, indicating that this strategy is highly promising for preparing advanced energy materials.