Tailoring Solvation Structure via Soft‐Hard Segment Synergy in Gel Polymer Electrolytes Enables Dendrite‐Free Sodium Batteries with Ultra‐Long Cycling

ABSTRACT The development of polymer electrolytes with high ionic conductivity, robust mechanical strength, and excellent interfacial stability remains a critical challenge for high‐performance sodium metal batteries (SMBs). Herein, a “chemical‐structural dual regulation” strategy introduces complementary soft and hard segments into a gel polymer electrolyte (GPE), enabling concurrent optimization of solvation structure and mechanical properties. Soft segments with strong electron‐withdrawing ‐CF 3 groups form solvent‐rich domains that weaken Na + ‐solvent interactions, while amide N–H groups create polymer‐rich domains that enhance mechanical strength and anchor anions via hydrogen bonding, promoting sodium salt dissociation. Benefiting from this rational molecular design, GPE‐9 delivers an outstanding ionic conductivity of 1.11 mS cm −1 and a high Na + transference number of 0.74 at room temperature, and supports long‐term cycling of Na||Na symmetric cell at 0.2 mA cm −2 for 7000 h. The Na|GPE‐9|Na 3 V 2 (PO 4 ) 3 (NVP) cell demonstrates excellent rate durability, sustaining 12 000 and 20 000 cycles at 5C and 10C, respectively, with nearly 100% Coulombic efficiency. Furthermore, a 29‐layer pouch cell with NVP cathode and hard carbon (HC) anode delivers a high capacity approaching 1.0 Ah. This study demonstrates that designing polymer segments capable of regulating solvation structure and directing interfacial fluorination offers a promising strategy for high‐performance GPEs for Na batteries.