Cationic–Zwitterionic Polymer Electrolytes with Enhanced Ionic Conductivity and Lithium‐Ion Selectivity for Solid‐State Batteries

Cationic–zwitterionic polymers are developed to address the low ionic conductivity and lithium-ion selectivity of polymer electrolytes. Sulfonate moieties facilitate cation dissociation and transport, while cationic groups confine anions electrostatically, yielding a conductivity of 1.6 mS cm⁻¹ and a lithium transference number of 0.76. These electrolytes demonstrate high safety and enable Ah-level lithium–metal batteries.

Abstract

Polymer electrolytes are attractive for solid-state lithium–metal batteries owing to their favorable interfacial compatibility and scalable processability. However, the concurrent realization of high ionic conductivity and a high lithium-ion transference number remains a significant key challenge. Herein, we report a class of cationic–zwitterionic polymer electrolytes that simultaneously exhibit high ionic conductivity and enhanced lithium-ion selectivity. The cationic segments within the polymer networks immobilize anions to promote selective lithium-ion transport, while sulfonate groups facilitate effective lithium salt dissociation and ion mobility. Structural and electrochemical analyses verify the stability and performance of these electrolytes in lithium symmetric cells and Li||LiFePO₄ batteries. Notably, a 1.2 Ah pouch cell incorporating the optimized electrolyte validates the practical scalability and safety, highlighting its promise for next-generation solid-state lithium–metal batteries.

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