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.