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Transition metal nitrides (TMNs) have great potential use in energy storage and conversion owing to tunable electronic and bonding characteristics. Novel iron rich nitrides nanoparticles anchored on the N‐doped porous carbon, named as (CoxFe1–x)3N@NPC (0 ≤ x < 0.5) are designed here. The synergistic effects of phase transition and electron‐spin regulation on oxygen electrocatalysis are testified. A core–shell structure of (CoxFe1–x)3N with high dispersibility is induced by an intermediate phase transition process, which significantly suppresses coarsening of the metallic nitrides. The Co incorporation regulates d‐band electrons spin polarization. The t2g5eg1 of FeII with the ideal eg electron filling boosts intrinsic activity. (Co0.17Fe0.83)3N@NPC with optimal cobalt content holds electronic configuration with moderate eg electron filling (t2g5eg1), which balances the adsorption of *O2 and the hydrogenation of *OH, improving bifunctional catalytic performances. Both liquid and solid‐state zinc–air batteries assembled based (Co0.17Fe0.83)3N@NPC cathodes substantially deliver higher peak power density and remarkable energy density. [ABSTRACT FROM AUTHOR]

The composite polymer electrolytes, consisting of a flexible matrix and superb fast ion conductor are promising for large-scale practical application in safer lithium metal batteries. The quantification of polymer structure evolution induced by the inorganic filler was rarely reported. Here, a designer cubic argyrodite Li 6 PS 5 X sulfide electrolyte was fabricated by a solid reaction. A stoichiometry deviation by increasing S and Li, reducing Cl contents, leads to a novel electrolyte of Li 6.25 PS 5.25 Cl 0.75 with high conductivity of 1.0 mS cm−1 and low activation energy of 0.14 eV at room temperature. The off-stoichiometry Li 6 PS 5 X sulfide electrolyte Li 6.25 PS 5.25 Cl 0.75 was used as active filler for polyethylene oxide. Small angle X-ray scattering experiment indicates that the Li 6.25 PS 5.25 Cl 0.75 triggers a pronounced structure evolution in the matrix. As a result, Li-ion diffusion pathway is expanded significantly by the Li 6.25 PS 5.25 Cl 0.75 additives. An optimum ionic conductivity of 1.4 mS cm−1 at 70 °C for CPEs-1 was obtained, and a LFP/Li demo battery delivers a high capacity retention of 91.1% for 100 cycles at 0.2 C. Unlabelled Image • A designer argyrodite Li 6 PS 5 X sulfide is fabricated by a solid reaction. • The stoichiometry deviation by increasing S and Li enhances the conductivity. • The interplay between Li 6.25 PS 5.25 Cl 0.75 and PEO membrane is quantified by SAXS. • The sulfide based novel CPEs delivers a stable cycling in a LFP|Li cell. [ABSTRACT FROM AUTHOR]