Rapid Targeted Repair of the Solid Electrolyte Interphase via a Hybrid Ester‐Ether Solvation Strategy for Stable Sodium Anodes

Sodium metal batteries are promising candidates for large‐scale energy storage due to their low cost and high energy density. However, the repeated formation and disruption of the solid electrolyte interphase (SEI) on the sodium anode significantly limits their long‐term cycling stability. Here, we propose a targeted SEI repair strategy using an ester‐ether hybrid solvation electrolyte. By confining reactive trimethyl phosphate (TMP) within a solvation shell dominated by diethylene glycol ether (G2), this design mitigates direct sodium anode corrosion by free TMP while simultaneously directing the preferential decomposition of solvated TMP at SEI defect sites, enabling rapid SEI restoration. Microstructural analysis confirms the formation of a robust composite SEI, rich in NaF and Na 3 PO 4 , which effectively suppresses dendrite growth due to its excellent mechanical integrity and high ionic conductivity. As a result, the Na||Na 3 V 2 (PO 4 ) 3 cell with this electrolyte exhibits enhanced cycling performance, retaining 90% capacity after 4500 cycles at 1 C and 98.5% after 950 cycles at 20 C. Furthermore, a pouch cell demonstrates the practical viability of this approach, delivering a stable specific capacity of 109.47 mAh g −1 after 350 cycles at 3 C and highlighting its potential for high‐performance sodium metal batteries.