Anion‐Immobilized Polar Nanochannels in Metal‐Organic Frameworks Enable Ion‐Decoupled Transport for High‐Performance Solid‐State Sodium Batteries

ABSTRACT The development of all‐solid‐state polymer sodium metal batteries (ASSP‐SMBs) is hindered by insufficient salt dissociation and imbalanced ion migration in polymer electrolytes. Herein, we propose an atomic level precise pore engineering strategy that integrates pore confinement with surface polarization in a metal‐organic framework (MOF) CAU‐10‐PyDC. The electron‐withdrawing effect of the pyridinic nitrogen atoms induces a localized positively charged microenvironment, which strongly anchors anions, promotes NaTFSI dissociation and establishes ion‐decoupled transport pathways with low energy barriers. Simultaneously, the optimized pore size offers a low‐energy‐barrier pathway for efficient Na + migration. Importantly, CAU‐10‐PyDC synergistically promoted polymer electrolyte (PyDC‐MSPE) induces the formation of stable, inorganic‐rich SEI and CEI layers, effectively suppressing dendrite growth and interfacial side reactions. The PyDC‐MSPE electrolyte demonstrates a high ionic conductivity of 3.37×10 −4 S cm −1 and a Na + transference number of 0.75. Na|PyDC‐MSPE|Na 3 V 2 (PO 4 ) 3 ASSP‐SMB maintains a specific capacity of 111.2 mAh g −1 after 1000 cycles at 2C. The corresponding pouch cell achieves an energy density of 325.7 Wh kg −1 , with high‐capacity retention of 87.7% after 100 cycles. This study unveils a novel mechanism where pore confinement synergizes surface polarization to regulate ion transport, offering an effective approach to addressing sodium salt dissociation and ion transport challenges in ASSP‐SMBs.