Elastic Bridging Design of a Fluorine‐Free Electrolyte Enables High‐Performance Lithium Batteries

ABSTRACT The escalating demand for lithium‐based batteries has underscored the urgency to address safety and environmental risks associated with conventional electrolytes. To mitigate these challenges, we propose a fluorine‐free electrolyte architecture leveraging tailored solvent‐polymer elastic bridging. This design encapsulated LiBOB‐based F‐free localized high‐concentration electrolyte within an elaborately synthesized zwitterionic polyurethane combining rigid‐flexible molecular motifs. The chain‐solvent elastic bridging strategy reconstructs the solvation environment through selective Li ⁺ ‐solvent coordination, while modulates weak intermolecular interactions in the polymer backbone to guide ion transport and further improve mechanical properties. Thus, the resultant fluorine‐free electrolyte achieves an extremely high lithium‐ion transference number of 0.95, high room‐temperature ionic conductivity of 1.3 mS cm ^{− 1} and high fracture strength of 1.1 MPa. These advancements synergize with the formation of an inorganic boride‐rich interfacial layer, enabling Li||Li symmetric cells to sustain plating/stripping of 1000 h. Moreover, solid‐state full cells achieve superior performance; for instance, the Li|| NCM622 (10 mg cm ⁻² ) cell exhibits an average capacity of 1.6 mAh cm ^{− 2} (140 mAh g ⁻¹ ) and a coulombic efficiency of 99.4% over 200 cycles, and a pouch cell also achieves a capacity of 1600 mAh. This work pioneers electrolyte design innovation through molecular solvent‐polymer synergy and macroscopic electrochemical integration, enabling sustainable fluorine‐free energy storage commercialization.