Synergistic Spin‐Polarization Effect and Magnetic Exchange Interaction of Core/Shell Structure for Bifunctional Oxygen Electrocatalysis

ABSTRACT Rechargeable zinc‐air batteries (RZABs) are hindered by sluggish oxygen reduction and evolution (ORR/OER) kinetics. While core/shell nanostructures can enhance bifunctional electrocatalysis via synergy, achieving precise interfacial electronic modulation and scalable synthesis for ampere‐hour‐level RZABs remain challenging. Herein, we report a scalable synthesis of nitrogen‐doped carbon‐supported CoCuNi/ZnMn 2 O 4 core/shell nanoparticles (CoCuNi/ZnMn 2 O 4 ‐NC) as an efficient bifunctional electrocatalyst. Leveraging electronegativity differences among transition‐metals, controlled morphology during gram‐scale production is achieved. The core/shell interaction elevates the spin state of surface Mn cations, enabling an antiferromagnetic‐to‐ferromagnetic transition. The dynamic equilibrium of *OH adsorption/desorption is facilitated, and the rate‐determining energy barrier is reduced by 0.17 and 0.15 eV compared to individual ZnMn 2 O 4 and CoCuNi, respectively. The catalyst exhibits outstanding bifunctional performance (ORR half‐wave potential = 0.941 V; OER overpotential = 430 mV at 10 mA cm −2 ) and robust stability. Liquid RZABs using CoCuNi/ZnMn 2 O 4 ‐NC achieve a peak power density of 244.4 mW cm −2 , a specific capacity of 802.5 mAh g − 1 , and stable cycling over 450 h. Practical viability is further confirmed by an 8.4 Ah quasi‐solid‐state pouch cell with an output power of 369 mW and a lifespan of 200 h. This work sheds light on designing and scaling core/shell electrocatalysts toward high‐energy, practical metal‐air batteries.