Triggering Interfacial Magnetoelectric Coupling at Layered Oxide Cathodes for High‐Rate Na‐Ion Storage

ABSTRACT Layered oxide cathodes have been recognized as prospective cathode materials for Na‐ion batteries (NIBs) owing to their high energy density and low cost. However, the cycling stability and rate capability are hindered by sluggish Na + diffusion kinetics and severe interfacial side reactions. Herein, a ferromagnetic layer is constructed at the interface between layered oxide cathodes and electrolyte, triggering a remarkable magnetoelectric effect to achieve high‐rate Na + storage. First, a uniform ion distribution across the cathode‐electrolyte interface is promoted, and interfacial ion accumulation is mitigated, as Na + ions are subjected during cycling to a Lorentz force generated by the combined tangential and normal magnetic components. Second, an interfacial electric field is formed between the ferromagnetic modification layer and the layered oxide cathode due to their different work function, significantly boosting the charge diffusion kinetics during the reversible reaction. Third, the magnetoelectric effect guides the nucleation and growth of the cathode‐electrolyte interface, promoting a thin, uniform, and NaF‐rich layer that enhances interfacial charge transfer. Consequently, the exceptional rate (up to 20 C) and cycling capabilities (78.2% retention after 1000 cycles) are achieved, highlighting the effectiveness and significance of regulating interfacial charge transport by activating the interfacial magnetoelectric coupling effect.