Anion-Immobilized Polar Nanochannels in Metal-Organic Frameworks Enable Ion-Decoupled Transport for High-Performance...

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|Na₃V₂(PO₄)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.