Engineering Solvation Sheath and Gradient Interphase via Pull‐Expulsion Dynamics for Low‐Temperature Quasi‐Solid‐State Sodium Metal Batteries

ABSTRACT Gel polymer electrolytes (GPEs) hold particular promise for solid‐state sodium metal batteries (SSMBs) owing to their inherent flexibility and processability. However, their practical implementation is severely constrained by sluggish ion transport kinetics and exacerbated dendrite growth at low temperatures. To tackle these issues, we propose a coordination‐driven pull‐expulsion dynamics strategy that employs poly(vinylene carbonate) (PVC) and residual monomer to address the aforementioned multifaceted bottlenecks simultaneously. The highly polar C─O groups in PVC chains actively extract Na + from the solvent‐separated ion pair solvation sheath, transforming them into contact ion pairs and aggregate structures, while residual VC monomers with low hindrance expel solvents and relax the solvation sheath. These concerted dynamics reduce solvent coordination around Na + , promote anion participation, and form a robust polymer‐rich gradient interphase, yielding a high ionic conductivity of 2.31 mS cm −1 at 25°C. As a result, at −30°C, the Na 3 V 2 (PO 4 ) 3 ||Na full cell achieves outstanding cycling stability (1000 cycles with 97% capacity retention at 3.8 V, and 93.3% retention even at 4.2 V after 300 cycles), and a remarkable rate capability of 20 C. This study provides crucial design guidance for durable SSMBs in extreme‐environment applications.