Solid polymer electrolytes are considered among the most promising candidates for developing practical solid-state sodium batteries. However, moderate ionic conductivity and narrow electrochemical windows hinder their further application. Herein, inspired by the Na⁺/K⁺ conduction in biological membranes, we report a (–COO^–)-modified covalent organic framework (COF) as a Na-ion quasi-solid-state electrolyte with sub-nanometre-sized Na⁺ transport zones (6.7–11.6 Å) created by adjacent –COO^– groups and COF inwalls. The quasi-solid-state electrolyte enables selective Na⁺ transport along specific areas that are electronegative with sub-nanometre dimensions, resulting in a Na⁺ conductivity of 1.30×10^–4 S cm^–1 and oxidative stability of up to 5.32 V (versus Na⁺/Na) at 25 ± 1 °C. Testing the quasi-solid-state electrolyte in Na||Na₃V₂(PO₄)₃ coin cell configuration demonstrates fast reaction dynamics, low polarization voltages, and a stable cycling performance over 1000 cycles at 60 mA g^–1 and 25 ± 1 °C with a 0.0048% capacity decay per cycle and a final discharge capacity of 83.5 mAh g⁻¹.

固体聚合物电解质被认为是开发实用固态钠电池最有希望的候选者之一。然而，适中的离子电导率和狭窄的电化学窗口阻碍了它们的进一步应用。在此，受生物膜中Na ⁺ /K ^{+传导的启发，我们报道了一种 (–COO – )- 修饰的共价有机骨架 (COF) 作为具有亚纳米级 Na +}的钠离子准固态电解质传输区 (6.7–11.6 Å) 由相邻的 –COO ^–组和 COF 内壁创建。准固态电解质使 Na ⁺能够沿着具有亚纳米尺寸的电负性特定区域选择性传输，从而产生 Na⁺在 25 ± 1 °C 时，电导率为 1.30×10 ^–4 S cm ^–1，氧化稳定性高达 5.32 V（相对于 Na ⁺ /Na）。_{在 Na||Na 3} V ₂ (PO ₄ ) ₃纽扣电池配置中测试准固态电解质证明了快速反应动力学、低极化电压和在 60 mA g ^–1和 25 ±下超过 1000 个循环的稳定循环性能1 °C，每个循环容量衰减 0.0048%，最终放电容量为 83.5 mAh g ^-1。