Transient Polarized Cavities Mediate an Ultrafast and Stable Graphite Anode for Potassium‐Ion Batteries

Conventional ester‐based electrolytes exhibit intrinsic limitations for potassium‐ion batteries (PIBs): ethylene carbonate is solid at room temperature, while propylene carbonate induces graphite exfoliation via solvent co‐intercalation and suffers from poor rate capability. To address these challenges, we design a dipole‐engineered electrolyte that enables the formation of transient polarized cavities upon K + desolvation. These cavities generate localized negative electrostatic potentials that attract incoming K + ions, effectively lowering the ion transport barrier. This mechanism not only enhances K + kinetics but also promotes the formation of a stable, ion‐conductive solid electrolyte interphase, enabling highly reversible K + (de)intercalation in graphite. As a result, the K||graphite half‐cell delivers a high capacity of 290 mAh g −1 at 50 mA g −1 with negligible decay over 16 months (> 1000 cycles), and retains 226 mAh g −1 even at 500 mA g −1 . This work reveals a cavity‐mediated ion transport mechanism that offers new insights for designing high‐rate, long‐life graphite anodes in PIBs.