Domain‐Pinned Ferroelectric‐Like Fields Drive Deep Zn ²⁺ Intercalation in Bi ₂ TeO ₅

ABSTRACT

Traditional MnO ₂ ‐ and V ₂ O ₅ ‐based frameworks remain among the most widely studied cathode systems for aqueous zinc‐ion batteries (AZIBs), yet persistent structural instability and sluggish Zn ²⁺ transport often result in severe polarization and capacity degradation during cycling. Herein, we report a domain‐pinned cathode platform based on Cr‐doped oxygen‐vacancy Bi ₂ TeO ₅ (Cr‐OvBTO). The synergistic combination of Cr/Ov engineering and the stereochemically active lone‐pair electrons of Bi ³⁺ and Te ⁴⁺ reconstructs localized ferroelectric‐like fields associated with electrostatic heterogeneity and built‐in potential gradients. Consequently, a more stabilized local electrostatic environment is established, thereby enhancing lattice stability during cycling. Contact potential difference mapping and migration‐barrier calculations reveal a 77 mV built‐in potential gradient and a substantially reduced Zn ²⁺ migration barrier from 0.75 to 0.34 eV, consistent with improved Zn ²⁺ transport kinetics. As a result, Cr‐OvBTO delivers reversible deep‐intercalation behavior (∼360 mA h g ⁻¹ ) together with stable high‐rate cycling performance, retaining ∼77% capacity over 2000 cycles at 2 A g ⁻¹ . More importantly, this work demonstrates that domain‐pinned ferroelectric‐like fields can transform deep Zn ²⁺ intercalation from a kinetically constrained process into a reversible and sustainable transport pathway.