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.